PDF File #1: DETAILED SUMMARY OF NON-P-GLYCOPROTEIN MULTIDRUG RESISTANCE IN THE OVERALL SCHEMA OF DRUG RESISTANCE.

• An intricate equilibrium of upstream factors, tumor factors and downstream factors causes drug resistance through their effect on the growth, proliferation and apoptosis of cancer cells. Upstream factors include drug sanctuaries (blood-brain barrier, blood-eye barrier, blood-testicle barrier), intrinsic tumor factors, and host factors that affect metabolism, distribution, and clearance of drugs. Tumor factors include non-ABC transporters that cause resistance to a single drug such as dihydrofolate reductase that mediates resistance to methotrexate. Tumor factors also include a variety of ATP-Binding Cassette (ABC) superfamily transporters that cause resistance to multiple drugs (increased expression of the cell membrane drug efflux transporters P-glycoprotein and BCRP, the cell membrane drug sequestrator MRP, the nuclear-cytoplasmic transporter LRP, the MRP-related Canalicular Multispecific Organic Anion Transporter c-MOAT, and the drug target-altering topoisomerase II enzyme; or decreased expression of drug-detoxifying glutathione enzyme GSH). Downstream factors include increased expression of the anti-apoptotic bcl-2 oncogene, amplification or increased expression of MYCN oncogene or other oncogenes, and amplification of the Murine Double Minute-2 (MDM2) cellular proliferation-promoting gene; or decreased expression of the p53 tumor suppressor gene or other tumor suppressor genes.

o Classical MDR to chemotherapy drugs is caused by increased expression of the transmembrane transporter P-glycoprotein, first described by Ling et al in 1974. Ling et al had extended the original observations of the phenomenon by in 1970 by Biedler and Riehm, and by DanØ in 1973. § Classical MDR broadly affects drug classes that include the

hydrophobic and amphipathic natural product drugs such as the epipodophyllotoxins (etoposide, teniposide), taxanes (taxol), vinca alkaloids (vincristine, vinblastine), antibiotics (dactinomycin), and anthracyclines (doxorubicin, daunorubicin).

§ Non-natural product drugs are unaffected by MDR and they include the alkylators (cyclophosphamide, ifosfamide), platinums (cisplatin, carboplatin), antimetabolites (cytarabine, methotrexate, mercaptopurine), and steroids (prednisone).

o The first form of non-P-glycoprotein MDR was described in 1992 by Cole and Deeley et al, who characterized the Multidrug Resistance-Associated Protein (now abbreviated as Multidrug Resistance Protein or MRP) in a multidrug-resistant human lung cancer cell line. § The human MRP family consists of at least 6 members: MRP1 that

is the MRP prototype, and at least five homologues, MRP2, MRP3,

MRP4, MRP5, and MRP6.

§ Many non-P-glycoprotein drug efflux pumps have been proposed but MRP is the most fully confirmed mechanism so far. The MRP gene is distantly related to the multidrug resistance MDR1 gene.

§ The cloning of the MRP gene, and the MRP cDNA transfection experiments, proved unequivocally that overexpression of MRP confers MDR in mammalian cells.

§ The MRP gene is localized to chromosome 16p13.1, and encodes a 7.8-8.2 kb mRNA transcript, which produces the 190-kDa membrane-bound MRP protein.

§ MRP confers MDR to the same natural product drugs that are substrates of the P-glycoprotein drug efflux pump, and additionally exhibits resistance to heavy metal anion substrates, arsenite, arsenate, and trivalent antimony.

§ The MRP protein is localized to the plasma membrane and Golgi region. It is N-glycosylated. It undergoes phosphorylation only at the serine residues due to the action of protein kinase C. the regulation of MRP is complex and occurs at multiple sites and is subjected to numerous environmental stimuli.

§ The physiologic role of MRP appears to be acting as the ATP-dependent export pump for substrates that include the conjugates for lipophilic compounds, glutathione, leukotriene C4, LTD4, LTE4, and S-(2,4-dinitrophenyl)-glutathione, and sequestering these compounds into protective MRP-expressing vesicles to prevent cytotoxicity to normal cells.

§ MRP protein is expressed in human malignancies that include acute lymphoblastic and myelogenous leukemia, B-cell chronic lymphocytic and promyelocytic leukemia, hairy cell leukemia, non-Hodgkin lymphoma, multiple myeloma, and neuroblastoma. It is also expressed in normal cells such as peripheral blood mononuclear cells (the protein immunostains with anti-MRP monoclonal antibodies; the mRNA is shown by reverse transcriptase polymerase chain reaction analysis, RT-PCR).

§ Definitive correlation of MRP overexpression with poor outcome has not been fully defined in human malignancies.

o Non-P-glycoprotein MDR could also be caused by the Atypical Multidrug Resistance Protein (AT-MDR), first described in 1987 by Beck et al and Danks et al, in T-cell acute lymphoblastic leukemia sublines selected with teniposide: § AT-MDR displays a cross-resistance profile very similar to the

phenotypes of the MDR1 P-glycoprotein and MRP1, with a few exceptions. It does not confer resistance to vinca alkaloids, and drug accumulation is no different between drug-resistant and drug-

sensitive cell lines.

§ AT-MDR apparently is mediated by the altered expression of the drug target-altering topoisomerase II enzyme.

§ The expression and clinical significance of AT-MDR in human malignancies remain undefined.

o Non-P-glycoprotein MDR could also by caused by the Lung Cancer Resistance Protein (now abbreviated as Lung Resistance Protein or LRP or LRP-56 after the anti-LRP monoclonal antibody LRP-56), first described in 1993 by Scheper et al in lung cancer cell lines that exhibited decreased drug accumulation: § LRP is a 110-kDa vesicular protein overexpressed in several MDR

cell lines, in normal epithelial cells, and in tissues (bronchi, intestine, renal tubules) exposed chronically to xenobiotics and potentially toxic agents.

§ The LRP gene has been cloned and demonstrates 60% homology (sequence identity) with the 104-kDa major vault protein from Dictyostelium discoideum.

§ Vault proteins are large cytoplasmic ribonucleoprotein structures found in eukaryotic cells. In rat liver, for example, there is one 104-kDa major vault protein and three 210-kDa, 192-kDa, and 54-kDa minor vault proteins that are hollow barrel-like multiunit organelles (two identical cup-like halves, each made of eight petal-like structures, joined at the open end) associated with cytoplasmic vesicle structures and nuclear pore complexes.

§ Vault proteins are highly conserved through the species.

§ LRP protein is overexpressed in human malignancies that include acute myelogenous leukemia. The clinical significance of LRP protein in human malignancies is not fully defined.

o Non-P-glycoprotein MDR could also be caused by the Mitoxantrone Resistance Protein MXR or Placenta-Specific ABC Protein ABCP1 or ABCG2 (now called Breast Cancer Resistance Protein or BCRP), first described in 1995 by Doyle and Ross et al: § The BCRP gene encodes a 2.4-kb mRNA transcript that translates

into the 655-amino acid BCRP protein. BCRP is a 95 kDa N-linked membrane sialoglycoprotein that is differentially glycosylated (72 kDa when unglycosylated).

§ The BCRP protein is identified in a number of cell lines.

§ The BCRP protein is identified as an ABC half-transporter member of the ATP-binding cassette (ABC) transporter superfamily. It is unique among the ABC half-transporters in being localized to the plasma membrane rather than to the intracellular membranes.

§ The BCRP drug efflux pump/xenobiotic transporter confers high-

level resistance to mitoxantrone, and resistance to other anthracylines (doxorubicin, daunorubicin), and to camptothecins.

§ In normal human tissues, the BCRP protein is found in the placental syncytiotrophoblasts, small intestine and colon epithelium, liver canalicular membrane, breast ducts and lobules, and in the venous and capillary endothelium but not in the arterial endothelium.

§ The apical localization of the BCRP protein in the small intestine and colon epithelium suggests a possible role in regulation of the back-transport of BCRP substrates that enter epithelial cells from the gut lumen.

§ The placental localization of the BCRP protein suggests a possible protective role for the fetus.

§ The BCRP protein is expressed in acute myeloid leukemia but its clinical relevance is not fully defined.

• P-glycoprotein remains the paradigm for understanding the subsequently described forms of multidrug resistance in the clinical and laboratory setting. The clinical relevance of non-P-glycoprotein MDR proteins has to be fully defined in clinical correlative studies. Merely identifying their presence in clinical samples is not sufficient; it requires: o The non-P-glycoprotein MDR protein should be detected before

treatment in non-responsive tumors, and conversely, not found in cured tumors.

o Prospective pretreatment evaluation of the tumor MDR protein should accurately predict the outcome of chemotherapy.

o Cures should be achievable by treating the tumors expressing the MDR protein with agents that could reverse MDR in vitro.

o Chemosensitizing agents that improve the response to chemotherapy drugs should specifically work by reversing MDR, rather than work indirectly by reducing the metabolic clearance of chemotherapy drugs.

• Some experimental studies show the reversal of non-P-glycoprotein MDR in vitro and in vivo.

• Effective but nontoxic MDR-reversal trials are not yet available in the clinic.

o

PDF File #2: DETAILED DESCRIPTION OF THE MULTIDRUG RESISTANCE PROTEIN MRP GENE FAMILY.

• MRP IN THE OVERALL SCHEMA OF THE ATP-BINDING CASSETTE (ABC) TRANSPORTER SUPERFAMILY:

o MRP and P-glycoprotein belong to the same large ATP-dependent transmembrane transporters superfamily, the ATP-Binding Cassette

(ABC) transporters superfamily.

o ABC transporters family members are prominent in many diseases including malaria, leishmaniasis and cancer.

o Several mammalian ABC transporters family members are involved in essential physiologic processes such as the sulfonylurea receptor SUR1 subunit of the ATP-sensitive potassium channel regulator of pancreatic beta cells in modulation of insulin secretion, the CFTR CAMP-regulated chloride channel of cystic fibrosis, and the TAP1 and TAP2 peptide transporters associated with antigen presentation by the major histocompatibility Class I molecules.

o Mutations of several ABC genes cause genetic disorders such as persistent hyperinsulinemia hypoglycemia of infancy (SUR1 mutation), Dubin-Johnson congenital hyperbilirubinemia (MOAT mutation), cystic fibrosis (CFTR mutation), and Stargardt’s disease with retina rod photoreceptor-related loss central vision of childhood (RIM or ABCR mutation).

• PHYLOGENETIC TREE SHOWING THE RELATIONSHIP BETWEEN MRP AND OTHER ABC TRANSPORTERS:

o This phylogenetic tree shows the close relationship between the human MRP homologues (MRP1, MRP2, MRP3, MRP4, MRP4, MRP5, MRP6, MRP7), human SUR1 (pancreatic beta cell sulfonylurea receptor/potassium channel regulator), murine SUR2 (brain and heart sulfonylurea receptor/potassium channel regulator), and human CFTR (cystic fibrosis receptor); whereas the human MDR1 and MDR3 homologues are more closely related to BSEP.

TABLE #1: THE PHYLOGENETIC TREE GENERATED USING THE CARBOXYL-TERMINUS OF EACH PROTEIN TO ALIGN WITH THAT OF MRP1

CFTR BSEP

MDR3 MDR1

SUR2 SUR1 MRP7

MRP5 MRP4 MRP6

MRP2

MRP3 MRP1

• STRUCTURAL FEATURES COMMON TO MRP AND OTHER ABC TRANSPORTERS:

o More than 200 prokaryotic and eukaryotic ABC proteins have been cloned and characterized; their common structural features include:

§ A hydrophobic polytopic membrane-spanning domain with up to six transmembrane helices.

§ A hydrophilic cytosolic nucleotide-binding domain containing three highly conserved sequence motifs, the Walker A motif, the Walker B motif, and the active transport family signature.

o In bacterial ABC proteins, these structural domains are usually encoded as separate polypeptides; they associate with one another to form an active transporter.

o In eukaryotic ABC protein transporters, there are usually four domains configured either as two alternating membrane-spanning domains and nucleotide-binding domains encoded as a single large polypeptide (eg, CFTR), or as two independently encoded half-molecules which then associate to function as a heterodimer (eg, TAP1/TAP2).

o The closest ABC proteins that share 30-90% identity and 48-96% similarity to MRP have similar but not identical functions to MRP.

TABLE #2: THE CLOSEST ABC PROTEINS THAT SHARE A HIGH DEGREE OF HOMOLOGY WITH MRP HAVE SIMILAR BUT NOT IDENTICAL FUNCTIONS TO MRP Species Protein Function Human MRP1 GS-X pump; Anionic conjugate transporter; MDR Mouse mrp GS-X pump; Anionic conjugate transporter; MDR Human MOAT/MRP2 GS-X pump; Liver anionic conjugate transporter Rabbit EBCR MOAT ortholog C. elegans mrp1 Heavy metal resistance C. elegans mrp2 Unknown Human MRP6 Unknown Yeast YCF1 Cadmium resistance; Vacuolar GS-X pump Arabidopsis AtMRP1 GS-X pump Human SUR1 Sulfonylurea receptor; Pancreas K+ channel

regulator Murine sur1 Sulfonylurea receptor; Brain, heart K+ channel

regulator Yeast YOR1/YRS1 Oligomycin resistance Leishmania LtpgpA Antimony and arsenic resistance

• DRUG RESISTANCE IN HUMAN CANCER:

o For the first ABC protein transporter, the 170 kDa P-glycoprotein (Ling et al, 1976) described, the human MDR1 gene has been cloned (Roninson et al, 1986), as has the mouse mdr1 gene (Gros et al, 1986), one hamster pgp gene (Gros et al, 1986), and the other 5 hamster pgp genes (Van der Bliek et al, 1986).

o For the second ABC protein transporter, the 190 kDa MRP protein (Cole and Deeley, 1992), the human MRP1 gene has been cloned (Cole and

Deeley, 1992). o These two mammalian ABC proteins differ substantially in a number of

important structural, mechanistic and pharmacological properties.

• THE MAMMALIAN P-GLYCOPROTEIN FAMILY:

o Only the Class I protein and Class II protein confer multidrug resistance by acting as a drug efflux pump in cancer cells.

o The physiologic function of Class I P-glycoprotein appears to protect against toxins at the blood-brain barrier.

o Class III P-glycoprotein does not confer multidrug resistance. o The physiologic function of Class III P-glycoprotein has not been fully

defined but it appears to function as the phosphatidylcholine translocator that regulates the secretion of phosphatidylcholine into bile.

TABLE #3: THE NOMENCLATURE FOR THE MAMMALIAN P-GLYCOPROTEIN GENES

Mammal Class I P-glycoprotein

Class II P-glycoprotein

Class III P-glycoprotein

Human gene

MDR1 — MDR3 (also called MDR2)

Mouse gene

mdr3 (also called mdr1a)

mdr1 (also called mdr1b)

mdr2

Rat gene mdr1a mdr1b mdr2

Hamster gene

pgp1 pgp2 pgp3

• THE MAMMALIAN MULTIDRUG RESISTANCE PROTEIN MRP FAMILY:

o The Multidrug Resistance Protein, first cloned by Cole and Deeley in 1992, is now known as MRP1.

o The MRP2 gene has been cloned in 1996 by Flens et al; by Buchler et al; and by Taniguchi et al.

o In the 1997 Gosau ABC transporters meeting, Marcel Kool introduced the concept of a MRP family with 5 members.

o In 1998, Kool et al added MRP6.

o A seventh family member of amphipathic anion transporters, MRP7 (ABCC10), was predicted from a database search. The MRP7 gene maps to chromosome 6p12-21, in proximity to several genes associated with glutathione conjugation and synthesis. It encodes a 158 kDa protein comprised of 1492 amino acids. The MRP7 protein resembles MRP1, MRP2, MRP3, and MRP6 structurally. It is expressed at low levels in

normal tissues. o In 1996, Allikmets et al. identified 21 other new ABC transporters on the

basis of conserved sequences.

o The MRP family group is clearly demarcated from the P-glycoprotein family group, CFTR, and the sulfonylurea receptor family group.

o The MRP family members fall into two groups – a group consisting of a larger number of amino acids, MRP1 (1531), MRP2 (1545), MRP3 (1527), and MRP6 (1503), and a group consisting of fewer amino acids, MRP4 (1325), and MRP5 (1437):

§ MRP1, MRP2, MRP3, and MRP6, have the highest homology, and possess the extra N-terminus domain lacking in MDR1.

§ The characteristic extra N-terminus extension of MRP1, MRP2, MRP3, and MRP6, with 5 transmembrane regions connected to a P-glycoprotein-like core by a cytoplasmic linker, is also seen in the other glutathione-drug conjugate (GS-X) pumps from simple eukaryotes like yeast and leishmania.

§ MRP4 and MRP5, which only have 40% identity with MRP1 and are smaller than MRP1, lack the extra N-terminus domain, but are still more homologous to the other MRP family members than to MDR1 or other ABC transporters.

§ The extra N-terminus domain is not necessary for transport activity.

§ The essential domain in MRP1, the linker domain zero, is conserved in the long N-terminus intracellular parts of MRP4 and MRP5.

o The Anthracycline-Associated Protein, ARA, is almost identical to the 3’ end of the MRP6 protein and found in epirubicin-selected leukemia cells.

o MRP2, characterized by Jansen et al as the Canalicular Multispecific Organic Anion Transporter (cMOAT), is missing in rats with an inborn error of metabolism in the biliary secretion of anions that include conjugated bilirubin. This is the origin of the alternative MOAT nomenclature for MRP family members.

o The sMRP is a cloning artefact, and represents the 3’ end of the MRP5 gene that is incidentally co-amplified with MRP1.

TABLE #4: THE DIFFERENT NOMENCLATURE OF MAMMALIAN MRP GENES IN THE LITERATURE

MRP Nomenclature

ABC Nomenclature

Alternative Names

Alternative Names

Alternative Names

MRP1 ABCC1 MRP

MRP2 ABCC2 cMOAT cMRP EBCR (rabbits)

MRP3 ABCC3 MOAT-D CMOAT-2 MLP-2

MRP4 ABCC4 MOAT-B

MRP5 ABCC5 MOAT-C PABC11 sMRP (only the 3’ end)

MRP6 ABCC6 MLP-1 ARA (only the 3’ end)

MRP7 ABCC10

• TRANSPORT FUNCTIONS OF THE MRP FAMILY MEMBERS:

o Up to now, 7 MRP family members are described that act as transporters of substances including:

§ organic anions and anionic drugs like methotrexate;

§ compounds converted to organic anions by conjugation with glutathione, glucuronide, and sulfate (which MDR1 has low-affinity for because of their negative charge);

§ neutral drugs conjugated to acidic ligands such as glutathione, glucuronide, and sulfate;

§ neutral organic drugs transported together with free glutathione, but not conjugated to the glutathione, glucuronide or sulfate acidic ligands.

o MRP family members act as GS-X pumps to cause resistance:

§ MRP1 transports drugs conjugated to glutathione out of cells, and possibly arsenite and antimony in complexes formed by combining with 3 glutathione molecules.

§ MRP2, MRP3, and MRP5 transport glutathione conjugates.

§ MRP1 and MRP2 transport anionic conjugates.

o MRP family members also transport other compounds to cause resistance:

§ MRP2/cMOAT probably transports cisplatin and carboplatin in complexes with glutathione.

§ MRP4 transports the nucleoside analogues 9-(2-phosphonylmethoxyethyl) adenine and azidothymidine monophosphate (anti-human immunodeficiency virus [HIV] drugs).

§ MRP family members also transport the nucleoside analogue anticancer drugs.

o The physiologic roles of MRP family members are related to their transporter functions:

§ MRP1 provides high-affinity transport for leukotriene C4 that

mediates response to inflammatory stimuli (eg, MRP1 knock-out mice without leukotriene C4 have an altered response to inflammatory stimuli).

§ MRP2 provides transport for the secretion of bilirubin glucuronide into bile (eg, humans without MRP2 develop a mild liver disease, Dubin-Johnson syndrome).

§ Other physiologic functions of the MRP family members are not known.

o The transporter functions of MRP family members are related to their intracellular locations:

§ Most of the MRP1 is not found in the plasma membrane but in intracellular vesicles.

§ MRP2 is routed to the apical membrane of kidney and other cells (supporting a protective function against toxins and drugs by efflux pump activity as in the case of MDR1).

§ MRP1, MRP3, and MRP5 are located in the basolateral membrane (indicating that the drugs tend to be pumped into cells rather than out of cells).

TABLE #5: THE TRANSPORTER FUNCTIONS OF MRP FAMILY MEMBERS & TISSUE LOCATIONS

MRP Family GS-X Pump Methotrexate Transporter

MDR Drugs Transporter

Tissue Locations

MRP1 + + + Ubiquitous but low in liver

MRP2 (cMOAT)

+ + + Liver, kidney, gut

MRP3 + + + Liver, adrenals, pancreas, kidney, gut

MRP4 ? Undefined Undefined Prostate, lung, muscle, pancreas, testis, ovary, bladder, gallbladder

MRP5 + Undefined Undefined Ubiquitous

MRP6 Undefined Undefined Undefined Liver, kidney

• SUMMARY OF MRP1 TRANSPORT FUNCTION:

o MRP1 is an organic anion transporter for anionic drugs such as

methotrexate. § MRP1 transports compounds conjugated with glutathione,

glucuronide and sulfate.

§ MRP1 confers resistance to vincristine, vinblastine, etoposide, doxorubicin, epirubicin, mitoxanthrone, and camptothecins CPT-11 and SN38, but not cisplatin.

§ MRP1 transports neutral drugs conjugated to the acidic glutathione, glucuronide and sulfate ligands.

§ MRP1 also co-transports together with free glutathione those neutral organic drugs that cannot be conjugated by glutathione, glucuronide and sulfate.

§ MRP1 is a GS-X pump that transports drugs conjugated to glutathione out of cells.

§ MRP1 confers resistance to arsenite and antimony by transporting them as complexes with three glutathione molecules.

§ MRP1 has a role in resistance against nucleoside analogues used as anticancer drugs.

§ The physiologic role of MRP1 is high-affinity transport of leukotriene C4, but its absence only alters the response to inflammatory stimuli without affecting the health otherwise.

• SUMMARY OF MRP2/cMOAT TRANSPORT FUNCTION:

o MRP2 handles a similar range of drugs like MRP1: § These drugs include methotrexate, cisplatin, vincristine, vinblastine,

doxorubicin, epirubicin, mitoxanthrone, and the camptothecins CPT-11 and SN38.

§ The situation with etoposide remains indeterminate. MRP2 antisense does not enhance sensitivity to etoposide, but transfection of the MRP2 gene does cause resistance to etoposide.

§ When the results of the transfection experiments are completed, the spectrum of drug resistance for MRP2 may turn out to be identical to that of MRP1, with the exception that MRP2 induces cisplatin resistance that is not seen in MRP1-expressing cells.

§ MRP2/cMOAT (like MRP5) functions much better at the intracellular membrane than the plasma membrane.

o MRP1 and MRP2 transport of vinca alkaloids and anthracylines that are weak organic bases not conjugated to acidic ligands.

§ Therefore, it is puzzling that MRP1 and MRP2 could confer vinca alkaloid and anthracycline resistance.

§ These drugs are probably co-transported with glutathione because: (1) intracellular depletion of glutathione abolishes MRP-mediated

vinca alkaloid and anthracycline resistance; (2) vesicular transport experiments of vincristine and doxorubicin work only in the presence of glutathione; (3) in MRP2-transfected polarized kidney cells, the increased transport of vinblastine is associated with a stoichiometrically increased export of glutathione.

§ It looks like MRP1-mediated MDR and MRP2-mediated MDR require a continuous supply of glutathione to allow the export of unconjugated drugs.

§ Indeed, there is often a simultaneous increase in the tumor cells of the expression of MRP1 and that of the glutathione synthetic enzyme, g����-glutamylcysteine synthetase.

• SUMMARY OF MRP3 TRANSPORT FUNCTION:

o MRP3 is also an organic anion transporter:

§ MRP3 prefers glucuronide conjugates as substrates; in contrast, MRP1 and MRP2 prefer glutathione conjugates as substrates.

§ In transfection experiments, MRP3 confers resistance to epipodophyllotoxins but not the other drugs.

§ MRP3 also confers resistance to short term exposure of methotrexate.

§ Technical transfection difficulties preclude the elucidation of the full range of MRP3 resistance.

§ The physiologic function of MRP3 remains to be established, but MRP3 may allow the efflux of organic anions from the liver into the blood when secretion into the bile is blocked. MRP3 may also have a role in the normal uptake of bile salts from the gut. This physiologic function is suggested by the basolateral location of MRP3 in the hepatic canalicular membrane, and the massive increase in liver expression of MRP3 in the liver during cholestasis.

§ It is also unknown why MRP3 expression is high in the adrenal cortex.

• SUMMARY OF MRP4 TRANSPORT FUNCTION:

o The function of MRP4 is less well defined compared to other family members. It has been shown to be an organic anion transporter and a nucleotide analogue pump. § MRP4 is recently found to function as a high-affinity cellular pump

for the anti-human immunodeficiency virus drugs, 9-(2-phosphonylmethoxyethyl) adenine (PMEA) and azidothymidine monophosphate (AZT), which are organic anions.

§ MRP4 also causes resistance to several nucleoside analogues including 9-(2-phosphonylmethoxyethyl) guanine that has antineoplastic activity. MRP4 (like MRP5) appears to be a

nucleotide analogue pump.

§ MRP4 may confer resistance to the anticancer base analogues such as mercaptopurine and thioguanine.

§ It still remains to be determined whether MRP4, like MRP5, causes clinical drug resistance in acute lymphoblastic leukemia and acute myelogenous leukemia that do not have the hypoxanthine phosphoribosyl transferase gene mutation.

§ MRP4 might be specific for phosphate conjugates.

§ It remains to be shown if MRP4 can also transport glutathione, glucuronide and sulfate conjugates.

§ MRP4’s physiologic function is unknown.

• SUMMARY OF MRP5 TRANSPORT FUNCTION:

o MRP5 is an organic anion transporter of glutathione conjugates and a nucleotide analogue pump (like MRP4). § MRP5 confers low-level resistance to the thiopurines, 6-

mercaptopurine, and 6-thioguanine.

§ MRP5 confers resistance to the anti-human immunodeficiency virus drug PMEA.

§ MRP5-expressing cells tend to accumulate less 6-mercaptopurine and less PMEA, and to extrude more 6-thioinosinemonophosphate and PMEA.

§ MRP5 does not appear to confer resistance to the other anticancer drugs, anthracyclines, vinca alkaloids, epipodophyllotoxins or methotrexate.

§ Some investigators, but not others, have reported that MRP5 confers resistance to the heavy metals cadmium chloride and potassium antimonyl tartrate.

§ MRP5 (like MRP2/cMOAT) functions better at the intracellular membrane rather than the plasma membrane.

§ It still remains to be determined whether MRP5, like MRP4, causes clinical drug resistance in acute lymphoblastic leukemia and acute myelogenous leukemia that do not have the hypoxanthine phosphoribosyl transferase gene mutation.

§ MRP5’s physiologic function is unknown.

• SUMMARY OF MRP6 TRANSPORT FUNCTION:

o The transporter function of MRP6 is undefined. The physiologic function is unclear. The role in multidrug resistance is unclear.

§ Recently, the 3’ end of the MRP6 protein is found to be almost identical to the anthracycline-associated protein, ARA, which is

found in epirubicin-selected leukemia cells.

§ MRP6 is highly expressed in the liver and kidney, but in low levels in other tissues.

§ Overexpression and amplification of the MRP6 gene are only found in resistant tumor cells that express concurrently high levels of MRP1 and showing MRP1 gene amplification. It is likely that the MRP6 gene is co-amplified with the MRP1 gene, because the location of the MRP6 gene is immediately adjacent to that of the MRP1 gene on 16p13.1.

TABLE #6: THE DRUG & PHYSIOLOGIC SUBSTRATES OF MDR1, MRP1 and cMOAT

ABC Transporter Drugs Physiologic Substrates

MDR1 Vinca alkaloid: vincristine, vinblastine Anthracycline: doxorubicin, daunorubicin, mitoxanthrone, bisantrene Epipodophylotoxin: etoposide, teniposide Taxane: taxol Antibiotic: dactinomycin Others: colchicine

Cortisol Aldosterone Dexamethasone

MRP1 Vinca alkaloid Anthracycline Epipodophylotoxin Taxane: poorly transported Others

Leukotriene C4 17 beta-estradiol 17-(beta-D-glucuronide) Bilirubin glucuronide Sulfated bile salts Oxidized glutathione Prostaglandin A Arsenite Antimony Aflatoxin B1

cMOAT/MRP2 Vinca alkaloid Camptothesin: CPT-11, SN-38 Platinum: cisplatin, carboplatin

Leukotriene C4 S-(2,4-dinitrophenyl)-glutathione Oxidized glutathione Bilirubin glucuronide Organic anions

TABLE #7: THE COMPARISON OF MDR1, MRP1, cMOAT/MRP2 AND MRP3

GENE MDR1 MRP1 cMOAT/MRP2 MRP3

KNOCK-OUTS MICE

mdr1a-/- & mdr1b-/- drug sensitive especially at blood-brain barrier; mdr2 phosphatidylcholine untranslocated

mrp1-/- high tissue glutathione.

No, but there are mutant rats naturally without MRP2.

Yes, technical problems, and still under study.

CHROMOSOME 7q21.1 16p13.1 10q24 17q22

TRANSCRIPT 4.5 kb 6.5 kb 6.5-7 kb 6.6 kb

PROTEIN P-glycoprotein Multidrug resistance protein

Canalicular multispecific organic anion transporter

MRP3

MOLE WEIGHT 170 kDA 190 kDA 190 kDA 190 kDA

AMINO ACIDS 1280 1531 1545 1527

TISSUES Adrenal, kidney, liver (canalicular membrane), colon, brain (endothelial cells/blood-brain barrier), uterus (pregnancy)

Placenta, testis, lung, skeletal muscle, heart, monocyte, liver (sinusoidal membrane)

Liver (canalicular membrane), duodenum, kidney

Liver, duodenum,

adrenal, pancreas

EPITHELIAL LOCATION

Apical membrane Basolateral membrane

Apical canalicular membrane of liver and kidney cells

Basolateral membrane

CANCERS Neuroblastoma, retinoblastoma, soft tissue and bone sarcoma, leukemia, lymphoma; breast, pancreas, colon, adrenal, liver, renal, ovarian, non-small cell lung carcinoma

Neuroblastoma, retinoblastoma, leukemia, lymphoma; non-small cell lung, anaplastic thyroid, esophageal, gastric, breast, bladder carcinoma

Undefined Undefined

CLINICAL CORRELATIVE STUDIES SHOWING SIGNIFICANCE

Neuroblastoma, retinoblastoma, soft tissue and bone sarcoma, leukemia, lymphoma, breast carcinoma

Neuroblast-oma, retinoblast-oma

Undefined Undefined

MULTIDRUG RESISTANCE PROFILE

Vinca alkaloid, Anthracycline, Epipodophylotoxin, Taxane, Antibiotic

Vinca alkaloid, Anthra-cycline, Podophylotoxin

Vinca alkaloid, Anthracycline, Camptothesin, Platinum

Vinca alkaloid, Anthracycline, Podophylotoxin, Platinum

METHOTREXATE RESISTANCE

Absent Present Present Present

INHIBITORS Verapamil, Cyclosporines, Carboxamides

High affinity substrates, Organic acids

Undefined Undefined

TABLE #8: THE COMPARISON OF THE OTHER MRP FAMILY MEMBERS

GENE MRP4 MRP5 MRP6 EST182763

KNOCK-OUTS MICE

No Yes but still under study

No No

CHROMOSOME 13q32 3q25-26 Immediately next to MRP1 on 16p13.1

6p21

TRANSCRIPT 6.5 kb 7 kb 6.5-7 kb 5.5 kb

PROTEIN MRP4 MRP5 MRP6 EST182763

MOLE WEIGHT 190 kDA 190 kDA 190 kDA 190 kDA

AMINO ACIDS 1325 1437 1503 Undefined

TISSUES Pancreas, skeletal muscle, lung, kidney, liver, prostate testis, ovary, bladder, gallbladder

Breast, skeletal muscle, pancreas, hippocampus

Pancreas, liver, kidney

Lung, liver, skeletal muscle

EPITHELIAL LOCATION

Undefined Basolateral membrane

Undefined Undefined

CANCERS Undefined Undefined Undefined Undefined

CLINICAL SIGNIFICANCE

Undefined Undefined Undefined Undefined

MDR PROFILE Undefined Undefined Undefined Undefined

METHOTREXATE RESISTANCE

Undefined Undefined Undefined Undefined

INHIBITORS Undefined Undefined Undefined Undefined

• TOPOLOGY & HIGHER ORDER STRUCTURE OF THE MRP FAMILY:

o The membrane topology and higher order structure of the MRP proteins illustrate how MRP proteins bind to substrates and hydrolyze ATP. Membrane topology and higher order structure of MRP proteins are studied using: § Monoclonal antibodies directed against known regions of the

protein and limited proteolysis to map the location of specific peptide sequences on either side of the plasma membrane;

§ Site-directed mutagenesis to determine which potential N-glycosylation sites are used;

§ Immunostaining of permeabilized cells with antisera and monoclonal antibodies to confirm the cytoplasmic location of hydrophilic nucleotide-binding domains 1 and 2;

§ Expression of individual and combinations of structural domains of MRP in a baculovirus system to measure the interactions in

functional assays;

§ Detergent-solubilized and lipid-reconstructed MRP protein to investigate the physical interaction of various MRP domains in electron microscopy and image analysis.

• THE PHYSIOLOGIC FUNCTIONS OF THE MRP PROTEIN FAMILY:

o Drug transport that includes: (1) cisplatin, vincristine, doxorubicin, and etoposide for MRP1; (2) cisplatin, vincristine, doxorubicin, but not etoposide for cMOAT/MRP2.

o Defense against internal and external toxins and toxic drugs that includes: (1) Caenorhabditis elegans MRP proteins protecting against heavy metal ions and toxins of the bacteria it ingests; (2) murine MRP proteins protecting against etoposide toxicity to the bone marrow, testis, kidney and oral and gut mucosa, protection that is lost in MRP1 knock-out mice.

o Different physiologic functions suggested by the different tissue distribution that includes: (1) placenta, testis, lung, skeletal muscle, heart, and monocytes for MRP1, but lower levels in the sinusoidal membrane of liver; (2) canalicular membrane of liver for cMOAT/MRP2, but lower levels in duodenum and kidney.

o Anionic conjugates, that are physiologic substrates of MRP1 protein actively transported by MRP1 into cells unidirectionally across basolateral epithelial membranes, include: (1) leukotriene C4; (2) endogenously formed organic anion conjugates, 17 beta-estradiol 17-(beta-D-glucuronide), bilirubin glucuronide, sulfated bile salts, and oxidized glutathione.

o Anionic conjugates, that are physiologic substrates of cMOAT/MRP2 protein actively transported by MRP2 unidirectionally across apical epithelial membranes out of cells into the extracellular space, include: (1) leukotriene C4; (2) glutathione, glucuronide and sulfate conjugates, glucuronosyl bilirubin, glucuronosyl estradiol, sulfatolithocholyltaurine, and oxidized glutathione.

o Different physiologic functions suggested by the subcellular localization that includes: (1) basolateral epithelial membranes for MRP1 to pump drugs and substrates into cells; (2) apical epithelial membranes for cMOAT/MRP2 (like P-glycoprotein) to pump drugs and substrates out of cells into the extracellular space, bile, urine, and gut.

o MRP1 as a basolateral epithelial transporter with protective functions that include: (1) protects the basal stem cell layer of the oral mucosa from destruction; (2) protects germ cells by the Sertoli cell basement membrane of the testicular tubule pumping drugs out from the testicular tubule; (3) protects the brain by the epithelial layer of the choroid plexus in the blood-brain barrier regulating the exchange of metabolites between the blood and cerebrospinal fluid (eg, MRP1 knock-out mice accumulate

considerable administered etoposide in the cerebrospinal fluid). o MRP1 as the major high affinity basolateral epithelial transporter of

leukotriene C4 that includes: (1) no recognized human disease in the absence of this major leukotriene C4 excretion pathway; (2) MRP1 knock-out mice appear more resistant than wild-type mice against inflammatory stimuli and bacterial infections possibly due to decreased leukotriene C4 secretion.

o MRP2 as the major apical epithelial transporter for the secretion of organic anions from the liver that includes: (1) humans without MRP2 develop liver disease due to the inability of the liver to excrete bilirubin-glucuronides; (2) there are no MRP2 knock-out mice but mutant rats without MRP2 are compromised in organic anionic excretion from the liver.

o MRP3 as a basolateral epithelial transporter that includes: (1) uptake of organic anions into intestinal cells; (2) removal of organic acids from bile into liver cells during cholestasis; (3) probable role in secretion of hydrophilic steroid hormones of the adrenal cortex.

o MRP5 transporter function is undefined but MRP5 knock-out mice have been generated that appear healthy and their pharmacology is under study.

• HEREDITARY DEFICIENCIES OF MRP1 AND MRP2 PROTEINS: o Dubin-Johnson syndrome: Patients have mutations localized mostly at

the first ATP-binding site in the cMOAT/MRP2 gene and present with hereditary conjugated hyperbilirubinemia - an inherited defect in the secretion of amphiphilic anionic conjugates from hepatocytes into bile, associated with deposition of a dark pigment in the hepatocytes. They have no cMOAT/MRP2 protein in the hepatic apical canalicular membrane, but normal expression of the MRP1 protein in hepatic and erythrocytic basolateral membranes. They show prolonged retention of sulfobromophthalein but otherwise normal liver functions.

o Hyperbilirubinemic TR-/GY mutant rats: Rats have no mrp2 protein in the hepatic apical canalicular membrane and cannot transport leukotriene C4, bilirubin glucuronide, and thyroxine glucuronide conjugates, or amphiphilic anions across the canalicular membrane.

o Hereditary deficiency of MRP1: Humans have no recognized disease in the absence of this major leukotriene C4 excretion pathway, but MRP1 knock-out mice with decreased leukotriene C4 secretion appear more resistant against inflammatory stimuli and bacterial infections.

• GLUTATHIONE-DRUG CONJUGATE (GS-X) PUMP IN CELLS EXPRESSING MRP THAT EXCRETE GLUTATHIONE (GSH):

o The MRP1 and MRP2/cMOAT GS-X pumps are: § Cisplatin transporters: cisplatin forms a 1:2 complex with

glutathione so that the cisplatin-glutathione complex is removed by the GS-X pump.

§ Organic anion transporters: for transport in liver membrane vesicles of leukotriene C4, dinitrophenyl glutathione, glutathione disulfide, glutathione conjugates of copper and zinc, bilirubin glucuronide, sulfobromophthalein, and other organic anions.

§ Non-anionic organic drug transporters: for anthracyclines and vinca alkaloids by conjugation to an anionic ligand (eg, glutathione, glucuronic acid, sulfate). Glutathione is required for the vesicular transport of vincristine by MRP1, and conversely, for the inhibition of MRP1-mediated organic anion transport by vincristine. Glutathione only binds to MRP1 with low affinity. Glutathione is apparently transported by MRP1 and MRP2, and probably required as an activator or a co-transported substrate.

§ Working hypothesis: MRP1 and MRP2 have 2 drug-binding sites for glutathione – the G-site (high affinity for glutathione but low affinity for drugs), and the D-site (high affinity for drugs but low affinity for glutathione). Without drugs, both sites are occupied by glutathione, exporting glutathione slowly. With low drug concentrations, the G-site is occupied by glutathione and the D-site, by drugs, co-transporting both compounds. With high drug concentrations, some negatively charged drugs occupy both sites, transporting only the drugs. Compounds and anticancer cells that are conjugated to glutathione, glucuronide and sulfate have high affinity for the D-site and G-site and are transported efficiently without requiring free glutathione or stimulating glutathione transport.

o The MRP3 GS-X pump has:

§ A low affinity for glutathione since cells with high expression of MRP3 do not secrete glutathione.

• MULTIDRUG TRANSPORTER IN CELLS EXPRESSING MRP:

o The MRP1 and MRP2/cMOAT multidrug transporters are: § Natural product anticancer drug transporters: transport indirectly

some (vinca alkaloids, anthracyclines, epipodophylotoxins), but not all, natural product anticancer drugs, by using a drug/glutathione co-transport mechanism. Glutathione appears more important for vinca alkaloid than anthracycline MRP1-mediated transport. High concentrations of etoposide appear to stimulate the drug/glutathione co-transport. It is not known precisely how MRP1-mediated transport is coupled to the energy providing ATP binding and hydrolysis. Glutathione by itself is not a substrate of MRP1, but MRP1 might mediate glutathione export in association with an as yet unidentified endogenous metabolite.

§ Methotrexate transporters: causing high level resistance to short methotrexate exposure, but do not transport polyglutamylated methotrexate during long methotrexate exposure.

§ High affinity leukotriene transporters: transport actively the cysteinyl leukotriene C4.

§ Glutathione-conjugated xenobiotic transporters: protect against chemical carcinogens such as glutathione-conjugated alflatoxin B1.

§ Protect against chemical carcinogenesis: transport actively other glutathione-conjugated xenobiotics including glutathione-conjugated alflatoxin B1.

o The MRP3 natural product anticancer drug transporter is:

§ A non-anionic organic drug transporter: for doxorubicin, etoposide, and vincristine.

§ A cisplatin transporter

§ An anionic organic drug transporter: but prefers glucuronides to glutathione as substrate.

§ A methotrexate transporter

o The MRP5 drug transporter is:

§ Probably thiopurine transporter

PDF File #3: DETAILED DESCRIPTION OF THE LUNG RESISTANCE PROTEIN LRP GENE FAMILY.

• The Lung Resistance Protein was first reported by Scheper et al in 1993:

o It is also called LRP-56 since LRP was first immunostained with the anti-LRP monoclonal antibody LRP-56 in lung cancer cell lines exhibiting non-P-glycoprotein reduced drug accumulation.

o The LRP gene has been cloned and demonstrates a 60% sequence identity (homology) with the 104-kDa major vault protein from Dictyostelium discoideum.

o The LRP gene is localized to chromosome 16p11.2, approximately 27 cM proximal to the location of the MRP1 gene at band 16p13.1.

o Vault proteins are large cytoplasmic ribonucleoprotein structures found in eukaryotic cells. For example, in rat liver, there is one major vault protein (104 kDa), and three minor vault proteins (210 kDa, 192 kDa, 54 kDa). Vault proteins are hollow barrel-like multiunit organelles consisting of 2 identical cup-like halves, each made of 8 petal-like structures joined at the open end, that are associated with cytoplasmic vesicle structures and nuclear pore complexes. Vault proteins are highly conserved through the species.

o Recently, two minor vault proteins have been identified, one of which is the telomerase-associated protein (TEP1), the other of which is the vault-poly (ADP-ribose) polymerase (VPARP).

o LRP is a 110-kDa vesicular protein overexpressed in several MDR cell lines, in normal epithelial cells, and in tissues chronically exposed to xenobiotics and potentially toxic agents, such as bronchial cells, and cells lining the intestines and kidney tubules.

o LRP protein is found in the kidney, adrenal, heart, lung, muscle, thyroid, prostate, bone marrow, and testis.

o LRP protein is overexpressed in human malignancies, including acute myelogenous leukemia, acute lymphoblastic leukemia, ovarian cancer, nonsmall-cell lung cancer, melanoma, neuroblastoma, osteosarcoma, and multiple myeloma, but a definitive clinical correlation with poor outcome of chemotherapy has not been not fully defined.

PDF File #4: DETAILED DESCRIPTION OF THE ATYPICAL MULTIDRUG RESISTANCE PROTEIN.

• The Atypical Multidrug Resistance Protein (Beck et al, 1987; Danks et al, 1987) was first described in CEM/VM-1, a non-P-glycoprotein multidrug-resistant, teniposide-selected T-cell acute lymphoblastic leukemia subline.

o AT-MDR is apparently mediated by altered activity or amount of the drug target-altering topoisomerase II (Topo II) enzyme characterized by:

§ Decreased Topo II catalytic and cleavage activity.

§ Decreased drug sensitivity, activity, and amount of nuclear matrix Topo II.

§ Increased ATP requirement of Topo II.

§ A single base mutation in Topo II results in a change of Arg to Gln at position 449, at the start of the motif B/nucleotide binding site.

§ Decreased Topo II phosphorylation suggesting decreased kinase or increased phosphatase activity.

o The DNA Topo II isozyme has a molecular weight of 170 kDa.

o Cytogenetic analysis indicates that the CEM/VM-1 subline contains an abnormally banded region on chromosome 13q, suggesting the presence of non-MDR1 gene amplification.

o AT-MDR displays a cross-resistant profile very similar to the MDR1 and MRP1 phenotypes:

§ Cross resistance to several drugs that interact with topoisomerase II, including teniposide, etoposide, amsacrine, doxorubicin, daunorubicin, and mitoxantrone.

§ Lack of vinca alkaloid resistance, unlike MDR1 and MRP1.

§ No cross resistance to dactinomycin or colchicine.

§ Absence of a drug accumulation defect, unlike MDR1.

o Altered expression of the topoisomerase II enzyme is described in relapsed acute lymphocytic leukemia, rhabdomyosarcoma, gastric carcinoma and testicular teratoma.

o The expression and clinical significance of AT-MDR in human malignancies are not fully defined.

PDF File #5: DETAILED DESCRIPTION OF THE BREAST CANCER RESISTANCE PROTEIN (BCRP).

• The Breast Cancer Resistance Protein (also called the Mitoxantrone Resistance Protein MXR or Placenta-Specific ABC Protein ABCP1 or ABCG2) is first described in 1995 by Doyle and Ross: o The BCRP gene has been cloned and sequenced by Doyle and Ross,

and its transfection into drug-sensitive cells causes overexpression of the BCRP protein conferring multidrug resistance.

§ It encodes a 2.4-kb mRNA transcript that translates into the 655-amino acid BCRP protein.

§ BCRP is a 95 kDa N-linked membrane sialoglycoprotein that is differentially glycosylated (72 kDa when unglycosylated).

§ BCRP protein is detected by immunostaining with the BXP-34 and BXP-21 monoclonal antibodies.

o BCRP is identified in a number of cell lines including the MCF-7/AdrVp breast cancer, NCI-H1688 small cell lung cancer, human ovarian tumor, resistant mouse fibroblast, EPF86-079 fibrosarcoma, S1 and HT29 human colon carcinoma, EPG85-257 gastric carcinoma, and human small-cell lung cancer cell lines.

§ The MCF-7/AdrVp cell line that shows particularly high resistance to mitoxanthrone has amplification of BCRP genomic DNA.

o BCRP has been identified as an ABC half-transporter member of the ATP-binding cassette transporter superfamily. Normally ABC full-transporters are expressed in the plasma membrane, whereas half-transporters are expressed in the intracellular membrane.

§ BCRP is unique among the ABC half-transporters in being localized to the plasma membrane rather than in the intracellular membrane.

§ The BCRP drug efflux pump/xenobiotic transporter confers high level resistance to mitoxantrone, and resistance to anthracylines (doxorubicin, daunorubicin), and camptothecins.

o In normal tissues, BCRP is found in placental syncytiotrophoblasts, small intestine and colon epithelium, liver canalicular membrane, breast ducts and lobules, and venous and capillary endothelium, but not arterial endothelium.

§ The apical localization of BCRP in the small intestine and colon epithelium suggests a possible role in regulation of the uptake of orally administered substrate drugs by back-transport from the gut lumen.

§ The placental localization of BCRP suggests a possible protective role for the fetus.

o BCRP expression is associated with low daunorubicin accumulation in acute myeloid leukemic blasts but its clinical relevance is not fully defined.

PDF File #6 DETAILED DESCRIPTION OF THE KEY CLINICAL CORRELATIVE STUDIES.

MDR1 with MRP1 expression: Zhou et al (1995) reported that the expression of MDR1 and

MRP1 impacted negatively on the outcome of chemotherapy for acute myelogenous leukemia, and that there may be a common mechanism for the induction mechanism of MDR1 and MRP1 overexpression. Schuurhuis et al (1995) reported that high expression of MDR1

and MRP1 in acute myelogenous leukemia correlates strongly with clinical resistance to combination chemotherapy. Van der Kolk et al (2000) reported that there is no association

between the expression of MRP1 and MDR1 and the overall survival of acute myelogenous leukemia patients.

MRP1 expression: Norris et al (1996) reported that high expression of the MRP

gene in patients with neuroblastoma correlates strongly with poor outcome, suggesting that MRP accounts for the association between amplification of the MYCN oncogene and the reduced survival. Chan et al (1997) reported that it is possible to detect low levels

of MRP1 expression in clinical neuroblastoma samples. Chan et al (1997) reported that it is the expression of MRP1,

rather than the expression of MDR1, that accounts for the rare failures of chemotherapy in retinoblastoma patients treated with a cyclosporine MDR-reversal of multidrug resistance protocol. This may explain why cyclosporine is sometimes ineffective as a chemosensitizer for some cancers treated with chemotherapy.

LRP expression: List et al (1996) reported that expression of the LRP protein

correlates with poor outcome in acute myelogenous leukemia. Filipits et al (1998) reported that expression of the LRP protein

predicts poor outcome in acute myelogenous leukemia. Outcome is best in patients lacking both LRP and MDR1 expression.

MDR1, MRP1 with LRP expression: Malayeri et al (1996) reported that the expression of MDR1,

MRP1 and LRP mediate multifactorial MDR in acute myelogenous leukemia. Broxterman et al (1999) reported that MDR1 function, but not

the expression of LRP or MRP1, correlates with a low steady-

state accumulation of daunorubicin in acute myelogenous leukemia. MDR1 activity, however, does not predict daunorubicin sensitivity in the blasts measured by an MTT-based assay. The contribution of MRP1 expression to reduced accumulation of daunorubicin appears minor compared to that of MDR1 expression.

BCRP expression: Ross et al (2000) reported that high expression of BCRP mRNA

is observed in 33% of acute myelogenous leukemia patients, suggesting that BCRP expression has a potential role in MDR.

PDF File #7 : DETAILED DESCRIPTION OF THE CLINICAL RELEVANCE & INHIBITION OF NON-P-GLYCOPROTEIN MDR.

• CLINICAL RELEVANCE OF MDR PROTEINS IN HUMAN CANCERS:

o MRP1 expression:

§ MRP1 is ubiquitous in human tissues and potentially could cause MDR in most tumors. MRP1 has been detected in every type of tumor but the correlation between MRP1 expression levels and clinical drug resistance is not strong. Since there are also no effective and specific inhibitors of MRP1, reversal studies could not be used to determine the role of MRP1 in causing clinical drug resistance.

o MRP2 expression:

§ No association has been found between the expression of MRP2 and MDR in drug-selected resistant cell lines. MRP2 has been reported in most cases of renal cell, lung, gastric, colorectal and hepatocellular carcinoma but the clinical significance is not known.

o MRP3 expression:

§ Initial studies have shown no association between the expression of MRP3 and MDR in in cell lines, but more recent studies of lung cancer cell lines show a strong correlation between the expression of MRP3 and resistance to doxorubicin, and a weaker correlation between the expression of MRP3 and resistance to vincristine, etoposide, and cisplatin.

o MRP and clinical methotrexate resistance:

§ The MRP1, MRP2 and MRP3 GS-X pumps protect cells against 4-hour high-dose methotrexate exposure but not against 96-hour low-

dose methotrexate exposure. Apparently, the loss of resistance during longer methotrexate exposures may be due to the build up of methotrexate during its polyglutamylation. There is competition between the export of methotrexate by MRP and the polyglutamylation of methotrexate, and methotrexate glutamates are not transported by MRP. Polyglutamylation of folates may also prevent MRP depletion of cellular folate pools.

o MRP and clinical cisplatin resistance:

§ Cisplatin forms complexes with glutathione that are still toxic and require removal from the cells by a GS-X pump. MRP2, but not MRP1, is the GS-X pump that removes the cisplatin-glutathione complexes. It has not been determined whether increased tumor MRP2 expression is associated with clinical cisplatin resistance.

o MRP and arsenite resistance:

§ Arsenite therapy could promote apoptosis and induce remission in acute promyelocytic leukemia, but arsenite resistance occurs quickly probably because of the overexpression of MRP. Experimental data suggest that arsenite increases the efflux of glutathione from cells that overexpress MRP1, MRP2, and MRP3. These cell lines that overexpress MRP1 are resistant to arsenite, whereas embryonal stem cells in which the MRP1 gene is disrupted are hypersensitive to arsenite.

o Clinical correlative studies: Most studies are descriptive and few clinical studies have shown a significant correlation between the expression of drug resistance proteins in clinical tumor samples and the outcome of the patients. Some clinical correlative studies have shown contradictory results. Clinical correlative studies include:

§ MDR1 and MRP1 expression:

Ø Zhou et al (1995) reported that the expression of MDR1 and MRP1 impacted negatively on the outcome of chemotherapy for acute myelogenous leukemia, and that there may be a common mechanism for the induction mechanism of MDR1 and MRP1 overexpression.

Ø Schuurhuis et al (1995) reported that high expression of MDR1 and MRP1 in acute myelogenous leukemia correlates strongly with clinical resistance to combination chemotherapy.

Ø Van der Kolk et al (2000) reported that there is no association between the expression of MRP1 and MDR1 and the overall survival of acute myelogenous leukemia patients.

§ MRP expression:

Ø Norris et al (1996) reported that high expression of the MRP gene in patients with neuroblastoma correlates strongly with

poor outcome, suggesting that MRP accounts for the association between amplification of the MYCN oncogene and the reduced survival.

Ø Chan et al (1997) reported that it is possible to detect low levels of MRP1 expression in clinical neuroblastoma samples.

Ø Chan et al (1997) reported that it is the expression of MRP1, rather than the expression of MDR1, that accounts for the rare failures of chemotherapy in retinoblastoma patients treated with a cyclosporine MDR-reversal of multidrug resistance protocol. This may explain why cyclosporine is sometimes ineffective as a chemosensitizer for some cancers treated with chemotherapy.

§ LRP expression:

Ø List et al (1996) reported that expression of the LRP protein correlates with poor outcome in acute myelogenous leukemia.

Ø Filipits et al (1998) reported that expression of the LRP protein predicts poor outcome in acute myelogenous leukemia. Outcome is best in patients lacking both LRP and MDR1 expression.

§ MDR1, MRP1 and LRP expression:

Ø Malayeri et al (1996) reported that the expression of MDR1, MRP1 and LRP mediate multifactorial MDR in acute myelogenous leukemia.

Ø Broxterman et al (1999) reported that MDR1 function, but not the expression of LRP or MRP1, correlates with a low steady-state accumulation of daunorubicin in acute myelogenous leukemia. MDR1 activity, however, does not predict daunorubicin sensitivity in the blasts measured by an MTT-based assay. The contribution of MRP1 expression to reduced accumulation of daunorubicin appears minor compared to that of MDR1 expression.

§ BCRP expression:

Ø Ross et al (2000) reported that high expression of BCRP mRNA is observed in 33% of acute myelogenous leukemia patients, suggesting that BCRP expression has a potential role in MDR.

§ MDR1, MRP1, Topoisomerase II, and BCL-2 expression:

Ø Lohri et al (1997) reported that the expression of MDR1 and MRP1 correlates with each other, with FAB M4 and M5 status, and with extramedullary disease in acute myelogenous leukemia, whereas low expression of BCL-2 correlates with a better outcome, low expression of topoisomerase II predicts with a poorer outcome, and lack of expression of MDR1 expression correlates with a better prognosis.

§ LRP, Heat Shock Protein 27, Glutathione-S-Transferase pi:

Ø Uozaki et al (1997) reported that overexpression of LRP, Glutathione-S-Transferase pi, and Heat Shock Protein 27 may be associated with failure of presurgery chemotherapy for osteosarcoma.

• PHYSIOLOGIC RELEVANCE OF THE PROTECTIVE FUNCTIONS OF MDR PROTEINS IN NORMAL HUMAN TISSUES:

o The basolateral epithelial location of MRP1 allows drugs to be pumped into cells, in contrast to the apical epithelial location of MDR1 and MRP2 that facilitates the efflux of drugs from cells.

§ MRP1 knock-out mice show no decrease in disposal of drugs, but are hypersensitive to etoposide because MRP1 does have a non-redundant protective function against the toxic effects of etoposide on the bone marrow, oropharyngeal epithelium, testicular tubules, and renal collecting ducts.

§ The basolateral location of MRP1 in Sertoli cells protects testicular tubules and germ cells against damage from drugs.

§ The protective function of MRP1 in the choroid plexus prevents the entry of drugs and toxins into the cerebrospinal fluid.

• INHIBITION OF NON-P-GLYCOPROTEIN MDR IN VITRO:

o The verapamil, cyclosporine A, the cyclosporine D analogue PSC 833, and the MS-209, GF120918 and GG918 carboxamide inhibitors that are effective in blocking MDR1 P-glycoprotein in vitro are ineffective for the MRP proteins, MRP1 and MRP2.

§ Most high affinity substrates of MRP1 and MRP2 are organic anions with a substantial hydrophobic moiety and at least one, but preferably two, negative changes.

§ The potent competitive inhibitors of MRP1 and MRP2 are their high affinity substrates, leukotriene C4, S-decylgluthione, and the leukotriene C4 antagonist MK571.

§ Other inhibitors of MRP1 are organic acids that are originally developed to inhibit the transport of uric acid, like sulfinpyrazone, benzbromarone, and probenecid.

§ Although MRP1 and MRP2 have similar substrate specificity, MRP1 inhibitors are not necessarily good MRP2 inhibitors. Sulfinpyrazone, for instance, does not inhibit the transport of the MRP2 substrate dinitrophenyl S-glutathione.

§ Negatively charged compounds do not enter cells readily, so there are no obvious lead compounds for the development of MRP1 and MRP2 inhibitors.

§ The primarily experimental and in vitro MRP inhibition studies:

Ø Rhodes et al (1994) reported that the Golgi inhibitor brefeldin A, and the H+ ATPase inhibitors, bafilomycin A1 and 7-chloro-4-nitrobenz-2-oxa-1,3-diazole, could inhibit the expression of MRP.

Ø Versantvoort et al (1994) reported that the iso-flavonoid tyrosine kinase inhibitor genistein could inhibit the expression of MRP.

Ø Versantvoort et al (1994) reported that the buthionine sulfoximine inhibitor of glutathione synthesis partially inhibited the expression of the MRP expression and reversed the daunorubicin accumulation deficit.

Ø Takeda et al (1994) reported that the tyrosine kinase inhibitor genistein could inhibit the expression of MRP.

Ø Feller et al (1995) reported that the buthionine sulfoximine inhibitor of glutathione synthesis depleted intracellular glutathione and inhibited the MRP-mediated cellular accumulation deficit of daunorubicin.

Ø Abe et al (1995) reported that the 1,4-dihydropyridine verapamil analogue could inhibit the expression of MRP and MDR1.

Ø Van der Graaf et al (1995) reported that the morpholino anthracyclines, methoxymorpholino anthracycline and cyanomorpholino anthracycline, could inhibit the expression of MRP and MDR1.

Ø Gekeler et al (1995) reported that the leukotriene C4 receptor antagonist MK571 could inhibit the expression of MRP.

Ø Gekeler et al (1995) reported that the specific bisindolylmaleimide protein kinase C inhibitor GF 109203II could inhibit the expression of MRP.

Ø Chaturvedi et al (1996) reported that the amido-keto pipecolinate derivative VX-710 could inhibit the expression of MDR1, and perhaps also expression of MRP1.

Ø Iersel et al (1996) reported that the alpha, beta-unsaturated carbonyl derivatives, curcumin, acrolein, cinnamaldehyde, citral, crotonaldehyde, ethacrynic acid, and trans-2-hexenal, could inhibit the expression of glutathione-S-transferase, by inhibition of the MRP1 glutathione conjugate GS-X export pump.

Ø Stewart et al (1996) reported that MRP1 mRNA and protein expression are reduced by antisense eicosomeric phosphorothioate oligonucleotides complementary to different regions along the entire length of the MRP mRNA.

Ø Germann et al (1997) reported that the pipecolinate derivative VX-710 is not only a potent modulator of MDR1-mediated multidrug resistance, but also affects multidrug resistance in

MRP-expressing cells perhaps in part by binding directly to the MRP protein.

Ø Chen et al (1997) reported that the pyridine analogue PAK-104P almost completely reverses the MRP1-mediated resistance to antimonials and arsenicals, and appears more effective than the gamma-glutamylcysteine synthetase inhibitor, buthione sulfoximine, which depletes intracellular glutathione.

Ø Sumizawa et al (1997) reported that the pyridine analogue PAK-104P completely reverses vincristine resistance by directly interacting with the MRP1 protein and inhibiting the MRP1 transporting activity.

Ø Vanhoefer et al (1997) reported that N,N-bis(2-chloroethyl)-N-nitrosourea carbamoylation of glutathione reductase inhibits MRP1 function.

Ø Soszynski and Bartosz (1997) reported that peroxynitrite inhibits glutathione conjugate-mediated transport and may affect MRP1 function.

Ø Gollapudi et al (1997) reported that probenecid reverses MDR in MRP1-expressing cell lines.

Ø Zhang et al (1997) reported that the New Caledonian sponge Neosiphonia superset cytotoxin, sphinxolide, depletes microfilament and circumvents MDR1 and MRP1 MDR.

Ø Martell et al (1997) reported that the glucose transport inhibitors, cytochalasin B and phloretin, block the active efflux of vincristine in MRP1-expressing cell lines.

Ø Draper et al (1997) reported that the cyclo-oxygenase inhibitor/glutathione-S-transferase inhibitor/anion transport modulator, indomethacin, mediates reversal of MRP1 function, but not MDR1 function, in human and murine cell lines.

Ø Jager et al (1997) reported that the tyrosine-kinase inhibitor genistein, a substrate of the uridindiphosphate-glucuronyltransferase isoenzymes, affects the cMOAT/MRP2 transport in liver.

Ø Chou et al (1998) reported that the hexahydropyrroloindole alkaloids, 5-N-acetylardeemin and 5-N-acetyl-8-demethylardeemin, reverse MRP1, MDR1 and LRP-associated MDR, increasing the intracellular accumulation of vinblastine and markedly decreased its efflux.

Ø Chuman et al (1998) reported that the pyridine analogue, PAK-104P, combines with the gamma-glutamylcysteine synthetase inhibitor, buthione sulfoximine, and reverses MRP-mediated vincristine resistance.

Ø Gao et al (1998) reported that the co-transfection of MDR1 antisense RNA and MRP antisense RNA abolishes MDR in a human lung cancer cell line that overexpresses both MDR1 and MRP1 proteins.

Ø Yanagisawa et al (1999) reported that the pipecolinate derivative VX-710 might be a useful modulator of both MDR1 and MRP1 expression in neuroblastoma.

Ø Roller et al (1999) reported that the inhibition by the nonsteroidal anti-inflammatory drugs (NSAID) of MRP1 expression in human glioma cells is at least in part responsible for the potentiation of doxorubicin and vincristine cytotoxicity.

Ø Marbeuf-Gueye et al (2000) reported that the pyridine analogue, PAK-104P, inhibited the MDR1 and MRP1-mediated efflux of anthracyclines and calceinacetoxymethyl ester whose efflux depends on the presence of glutathione.

Ø Okumura et al (2000) reported that a taxoid from the Japanese yew Taxus cuspidata, 5-O-benzoylated taxinine K, reverses MDR1 and MRP1-mediated MDR.

Ø Payen et al (2001) reported that the diabetes mellitus therapy sulphonylurea glibenclamide could block the activity of ABC transporters, inhibit MRP1-mediated MDR in a human lung cancer cell line, and block organic anionic efflux from MRP2-expressing hepatocytes.

• INHIBITION OF NON-P-GLYCOPROTEIN MDR IN VIVO:

o A number of compounds that showed in vitro inhibition of the function of MRP have also been tested in vivo.

§ None of these experimental compounds for inhibiting the function of MRP have translated to clinical usage so far.

Ø Massart et al (1996) reported that S9788 inhibits MRP1 expression in medullary thyroid carcinoma xenografts in nude mice.

Ø Vanhoefer et al (1996) reported that glutathione depletion by buthionine sulfoximine reverses mrp1 expression, but not mdr1 expression, in nude mice xenografts.

Ø Vanhoefer et al (1996) reported that d,l-buthionine-(S,R)-sulfoximine inhibits glutathione biosynthesis in MRP1-expressing nude mice xenografts.

• INHIBITION OF NON-P-GLYCOPROTEIN MDR IN THE CLINIC:

§ Peck et al (1996) reported acceptable toxicity but no objective responses in a Phase I clinical trial of VX-710 aimed at blocking the expression of MRP1 and MDR1.

§ It remains to be determined whether long term inhibition of MRP would be tolerated because of the far-reaching physiologic functions of the MRP family members, assuming that suitably efficacious and non-toxic MRP inhibitors could would be found.

PDF File #8: DETAILED CONCLUSIONS.

• Drug resistance is due to the cumulative endpoint, in a particular individual, of all the applicable and operative UPSTREAM FACTORS (drug sanctuaries, intrinsic tumor factors, drug metabolism, distribution and clearance factors), TUMOR FACTORS (ATP-Binding Cassette ABC superfamily transporters and non-ABC transporters), and DOWNSTREAM FACTORS (anti-apoptotic bcl-2 family of oncogenes, MYCN and other oncogenes, p53 and other tumor suppressor genes, and Murine Double Minute-2 MDM2 cellular proliferation-promoting gene).

• ATP-dependent transmembrane transporters-MDR mediators include, but are not limited to, P-glycoprotein (MDR1 and family members of cell membrane drug efflux transporters), Multidrug Resistance Protein (MRP1 and MRP2/cMOAT and family members of cell membrane drug sequestrator), Lung Resistance Protein (LRP nuclear-cytoplasmic transporter), Breast Cancer Resistance Protein (BCRP cell membrane drug efflux transporter), topoisomerase II (drug target-altering enzyme), and glutathione (GSH drug-detoxifying enzyme).

• MDR1/ P-glycoprotein MDR broadly affects many natural product drug classes including the epipodophyllotoxins (etoposide, teniposide), taxanes (taxol), vinca alkaloids (vincristine, vinblastine), antibiotics (dactinomycin), and anthracyclines (doxorubicin, daunorubicin). o Non-natural product drugs are not affected by MDR and include

alkylators (cyclophosphamide, ifosfamide), platinums (cisplatin, carboplatin), antimetabolites (cytarabine, methotrexate, mercaptopurine), and steroids (prednisone).

o Chemotherapy drugs and naturally occurring toxins are natural products that enter cells by passive diffusion through the lipid bilayer of the plasma membrane. The rate of entry takes minutes since drug entry is retarded by its hydrophilic components. These natural products are hydrophobic and could diffuse through the lipid bilayer, but are still hydrophilic enough to be water-soluble and reach the drug targets. They do not need carrier proteins that the cells can target as a protective mechanism, such as the reduced folate carrier, dihydrofolate reductase, for the water-soluble drug methotrexate.

• Genes encoding proteins that are drug pumps and drug-conjugate pumps are prominent in the genome across all species. o The three classes of human drug pumps are the P-glycoprotein family of

proteins, the MRP proteins, and the BCRP proteins, with 12 members

proteins, the MRP proteins, and the BCRP proteins, with 12 members presently identified.

o A large number of drug pumps are required because of the broad variety of substrates that they transported.

o The P-glycoprotein family of proteins could transport a wide range of neutral or slightly basic organic compounds.

• The MRP family proteins are more versatile transporters. The human MRP family consists of at least 6 members, MRP1 which is the MRP prototype, and at least five homologues, MRP2, MRP3, MRP4, MRP5, and MRP6.

o MRP1, MRP2, and MRP3 transport the neutral or slightly basic organic drugs and compounds, organic anionic compounds, neutral drugs conjugated to acidic glutathione, glucuronide and sulfate ligands via the GS-X pump, anionic drugs such as methotrexate, arsenite and antimony complexed with glutathione, cisplatin complexed with glutathione (MRP2), the physiologic leukotriene C4, and possibly the nucleoside analogues.

o MRP4 and MRP5 transport nucleotide analogues such as the anti-human immunodeficiency virus drugs phosphated PMEA and AZT nucleotide analogues, the antineoplastic mercaptopurine and thioguanine nucleotide analogues, organic anionic compounds and drugs, possibly the heavy metal conjugates, and possibly the glutathione, glucuronide and sulfate conjugates.

o The transport function of MRP remains undefined.

• MRP1 is a 190-kDa membrane-bound encoded by the MRP1 gene localized to chromosome 16p13.1, first described by Cole and Deeley and coworkers in 1992. o The physiologic role of MRP may be to function as the ATP-dependent

export pump for substrates that include the conjugates of the lipophilic compounds, glutathione, leukotriene C4, LTD4, LTE4, and S-(2,4-dinitrophenyl)-glutathione, sequestering these compounds into MRP-expressing vesicles to prevent their cytotoxicity to normal cells.

o MRP protein is expressed in human malignancies such as leukemia, lymphoma, myeloma, and neuroblastoma, and in normal peripheral blood mononuclear cells (MRP protein immunostained by the anti-MRP monoclonal antibodies, and MRP mRNA shown by the reverse transcriptase polymerase chain reaction analysis (RT-PCR).

o The definitive clinical correlation of MRP overexpression with poor outcome of chemotherapy is not fully defined in malignancies.

• LRP is a 110-kDa vesicular protein for which the LRP gene has been cloned, first reported by Scheper et al in 1993. o LRP demonstrates 60% homology with the 104-kDa major vault protein

of Dictyostelium discoideum. Vault proteins are large cytoplasmic

ribonucleoprotein structures found in eukaryotic cells. Vault proteins are highly conserved through the species.

o LRP protein is overexpressed in human malignancies such as acute myelogenous leukemia but a definitive clinical correlation with poor outcome of chemotherapy is not fully defined.

• AT-MDR was described by Beck et al in 1987, and by Danks et al in 1987, in non-P-glycoprotein multidrug-resistant T-cell acute lymphoblastic leukemia sublines selected with teniposide. o AT-MDR displays a cross-resistant profile very similar to the MDR1 and

MRP1 phenotypes, except for the lack of vinca alkaloid resistance, and the absence of a drug accumulation deficit.

o AT-MDR is apparently mediated by altered expression of the drug target-altering topoisomerase II enzyme.

o The expression and clinical significance of AT-MDR in human malignancies are undefined.

• BCRP is also called Mitoxantrone Resistance Protein MXR or Placenta-Specific ABC Protein ABCP1 or ABCG2, described in 1995 by Doyle and Ross and coworkers. o BCRP is a 95 kDa N-linked membrane sialoglycoprotein. It is identified

as an ABC half-transporter member of the ATP-binding cassette (ABC) transporter superfamily that is expressed in the plasma membrane unlike other half-transporters that are expressed in the intracellular membranes.

o The BCRP confers a high level of resistance to mitoxantrone, and resistance to the other anthracylines, doxorubicin and daunorubicin, and the camptothecins.

o BCRP is found in the placental syncytiotrophoblasts most likely for protecting the fetus. The apical localization of BCRP in the small intestine and colon epithelium suggests possible regulation of the back-transport of the substrate drugs that enter into cells from the gut lumen. BCRP is also found in the liver canalicular membrane, breast ducts and lobules, and the venous and capillary endothelium, but not the arterial endothelium.

o BCRP is expressed in acute myeloid leukemia but its clinical significance is not fully defined.

• Experimental studies could reverse multidrug resistance in vitro and in vivo, but MDR-reversal trials that are relatively nontoxic and yet efficacious are still not available in the clinical setting.

PDF File #9 : ADDITIONAL BIBLIOGRAPHY:

Abe T, Mori T, Wakabayashi Y, Nakagawa M, Cole SP, Koike K, Kuwano M, Hori S. Expression of multidrug resistance protein gene in patients with glioma after chemotherapy. J Neurooncol 1998; 40 (1): 11-18[Medline]. Akita H, Suzuki H, Ito K, Kinoshita S, Sato N, Takikawa H, Sugiyama Y. Characterization of bile acid transport mediated by multidrug resistance associated protein 2 and bile salt export pump. Biochim Biophys Acta 2001; 1511 (1): 7-16[Medline]. Allen JD, Brinkhuis RF, Wijnholds J, Schinkel AH. The mouse Bcrp1/Mxr/Abcp gene: amplification and overexpression in cell lines selected for resistance to topotecan, mitoxantrone, or doxorubicin. Cancer Res 1999; 59 (17): 4237-4241[Medline]. Almquist KC, Loe DW, Hipfner DR, Mackie JE, Cole SPC, Deeley RG. Characterization of the M(r) 190,000 multidrug resistance protein (MRP) in drug-selected and transfected human tumor cell. Cancer Research 1995; 55 (1): 102-110[Medline]. Bahr O, Wick W, Weller M. Modulation of MDR/MRP by wild-type and mutant p53. J Clin Invest 2001; 107 (5): 643-645[Medline]. Bakos E, Evers R, Calenda G, Tusnady GE, Szakacs G, Varadi A, Sarkadi B. Characterization of the amino-terminal regions in the human multidrug resistance protein (MRP1). J Cell Sci 2000; 113 Pt 24 4451-4461[Medline]. Ballinger JR. Imaging multidrug resistance with radiolabeled substrates for P- glycoprotein and multidrug resistance protein. Cancer Biother Radiopharm 2001; 16 (1): 1-7[Medline]. Beck WT, Cirtain MC, Ashmun RA, Mirro J. Differentiation and the multiple drug resistance phenotype in human leukemic cells. Cancer Research 1986; 46 (9): 4571-4575[Medline]. Beck WT, Cirtain MC, Danks MK, Felsted RL, Safa AR, Wolverton JS, Suttle DP, Trent JM. Pharmacological, molecular, and cytogenetic analysis of "atypical" multidrug-resistant human leukemic cells. Cancer Research 1987; 47 (20): 5455-5460[Medline]. Beck WT. The cell biology of multiple drug resistance. Biochemical Pharmacology 1987; 36 (18): 2879-2887[Medline]. Beck WT. Unknotting the complexities of multidrug resistance: the involvement of DNA topoisomerases in drug action and resistance. Journal of the National Cancer Institute 1989; 81 (22): 1683-1685[Medline]. Beck WT. Strategies to circumvent multidrug resistance due to P-glycoprotein or to altered DNA topoisomerase II. Bulletin du Cancer 1990; 77 (11): 1131-1141[Medline].

Beck WT. Mechanisms of multidrug resistance in human tumor cells. The roles of P-glycoprotein, DNA topoisomerase II, and other factors. Cancer Treatment Reviews 1990; 17 Suppl A 11-20[Medline]. Beck WT, Danks MK. Mechanisms of resistance to drugs that inhibit DNA topoisomerases. Seminars in Cancer Biology 1991; 2 (4): 235-244[Medline]. Beck WT, Danks MK, Wolverton JS, Granzen B, Chen M, Schmidt CA, Bugg BY, Friche E, Suttle DP. Altered DNA topoisomerase II in multidrug resistance. Cytotechnology 1993; 11 (2): 115-119[Medline]. Beck WT, Danks MK, Wolverton JS, Kim R, Chen M. Drug resistance associated with altered DNA topoisomerase II. Advances in Enzyme Regulation 1993; 33 113-127[Medline]. Beck WT, Kim R, Chen M. Novel actions of inhibitors of DNA topoisomerase II in drug-resistant tumor cells. Cancer Chemotherapy and Pharmacology 1994; 34 Suppl. S14-S18[Medline]. Beck WT, Danks MK, Wolverton JS, Chen M, Granzen B, Kim R, Suttle DP. Resistance of mammalian tumor cells to inhibitors of DNA topoisomerase II. Advances in Pharmacology 1994; 29B 145-169[Medline]. Beck WT, Grogan TM, Willman C, Cordon-Cardo C, Parham DM, Kuttesch JF, Andreeff M, Bates SE, Berard CW, Boyett JM, Brophy NA, Broxterman HJ, Chan HSL, Dalton WS, Dietel M, Fojo AT, Gascoyne RD, Head D, Houghton PJ, Srivastava DK, Lehnert M, Leith CP, Paietta E, Pavelic Z, Rimsza L, Roninson IB, Sikic BI, Twentyman PR, Warnke R, Weinstein R. Methods to detect P-glycoprotein-associated multidrug resistance in patients' tumors: consensus recommendations. Cancer Research 1996; 56 3010-3020[Medline]. Beck J, Regele B, Brugger D, Dietl J, Scheper RJ, Niethammer D, Bader P, Hirsch HA, Gekeler V. Expression of genes (MDR1, MRP, LRP, topoisomerases, PKC isozymes) possibly involved in drug resistance of ovarian carcinoma ascites cell aspirates. Proceedings of the American Association for Cancer Research 1996; 37 Abstract 2100[Medline]. Beck WT, Khelifa T, Kusumoto H, Mo YY, Rodgers Q, Wolverton JS, Wang Q. Novel mechanisms of resistance to inhibitors of DNA topoisomerases. Advances in Enzyme Regulation 1997; 37 17-26[Medline]. Beck WT, Grogan TM. Methods to detect P-glycoprotein and implications for other drug resistance-associated proteins. Leukemia 1997; 11 (7): 1107-1109[Medline]. Benard J, Rixe O. Resistance to anticancer drugs. Presse Medicale 1996; 25 (35): 1724-1730[Medline].

Bergen AA, Plomp AS, Schuurman EJ, Terry S, Breuning M, Dauwerse H, Swart J, Kool M, van Soest S, Baas F, ten Brink JB, de Jong PT. Mutations in ABCC6 cause pseudoxanthoma elasticum. Nat Genet 2000; 25 (2): 228-231[Medline]. Bonnal C, Calvo F. Resistance to antineoplastic treatments: mechanisms, clinical value. Comptes Rendus des Seances de la Societe de Biologie et de Ses Filiales 1996; 190 (4): 455-466[Medline]. Borst P, Kool M, Evers R. Do cMOAT (MRP2) and other homologues, and LRP play a role in MDR? Seminars in Cancer Biology 1997; 8 205-213[Medline]. Borst P, Evers R, Kool M, Wijnholds J. The multidrug resistance protein family. Biochim Biophys Acta 1999; 1461 (2): 347-357[Medline]. Borst P. Multidrug resistance: a solvable problem? Ann Oncol 1999; 10 (Suppl 4): 162-164[Medline]. Borst P, Evers R, Kool M, Wijnholds J. A family of drug transporters: the multidrug resistance-associated proteins. J Natl Cancer Inst 2000; 92 (16): 1295-1302[Medline]. Borst P, Zelcer N, van Helvoort A. ABC transporters in lipid transport. Biochim Biophys Acta 2000; 1486 (1): 128-144[Medline]. Brock I, Hipfner DR, Nielsen BS, Jensen PB, Deeley RG, Cole SP, Sehested M. Sequential coexpression of the multidrug resistance genes MRP and mdr1 and their products in VP-16 (etoposide)-selected H69 small cell lung cancer cells. Cancer Research 1995; 55 (3): 459-462[Medline]. Broxterman HJ, Kuiper CM, Schuurhuis GJ, Ossenkoppele GJ, Feller N, Scheper RJ, Lankelma J, Pinedo HM. Analysis of P-glycoprotein (Pgp) and non-Pgp multidrug resistance in acute myeloid leukemia. Proceedings of the American Association for Cancer Research 1994; 35 Abstract 2075[Medline]. Broxterman HJ, Schuurhuis GJ. Transport proteins in drug resistance: detection and prognostic significance in acute myeloid leukemia. Journal of Internal Medicine Supplement 1997; 740 147-151[Medline]. Broxterman HJ, Sonneveld P, Pieters R, Lankelma J, Eekman CA, Loonen AH, Schoester M, Ossenkoppele GJ, Lowenberg B, Pinedo HM, Schuurhuis GJ. Do P-glycoprotein and major vault protein (MVP/LRP) expression correlate with in vitro daunorubicin resistance in acute myeloid leukemia? Leukemia 1999; 13 (2): 258-265[Medline]. Bugg BY, Danks MK, Beck WT, Suttle DP. Expression of a mutant DNA Topoisomerase II in CCRF-CEM human leukemic cells selected for resistance to

teniposide. Proceedings of the National Academy of Sciences of the United States of America 1991; 88 (17): 7654-7658[Medline]. Campling BG, Pym J, Baker HM, Cole SPV, Lam YM. Chemosensitivity testing of small cell lung cancer using the MTT assay. British Journal of Cancer 1991; 63 (1): 75-83[Medline]. Campling BG, Baer K, Baker HM, Lam YM, Cole SP. Do glutathione and related enzymes play a role in drug resistance in small cell lung cancer cell lines? British Journal of Cancer 1993; 68 (2): 327-335[Medline]. Campling BG, Young LC, Baer KA, Lam YM, Deeley RG, Cole SP, Gerlach JH. Expression of the MRP and MDR1 multidrug resistance genes in small cell lung cancer. Clin Cancer Res 1997; 3 (1): 115-122[Medline]. Canitrot Y, Bichat F, Cole SP, Deeley RG, Gerlach JH, Bastian G, Arvelo F, Poupon MF. Multidrug resistance genes (MRP) and MDR1 expression in small cell lung cancer xenografts: relationship with response to chemotherapy. Cancer Lett 1998; 130 (1-2): 133-141[Medline]. Cantz T, Nies AT, Brom M, Hofmann AF, Keppler D. MRP2, a human conjugate export pump, is present and transports fluo 3 into apical vacuoles of Hep G2 cells. Am J Physiol Gastrointest Liver Physiol 2000; 278 (4): G522-531[Medline]. Chan HSL, Lu Y, Grogan TM, Haddad G, Hipfner DR, Cole SPC, Deeley RG, Ling V, Gallie BL. Multidrug Resistance Protein (MRP) expression in retinoblastoma correlates with rare failure of chemotherapy despite cyclosporine for reversal of P-glycoprotein. Cancer Research 1997; 57 2325-2330[Medline]. Chan HSL, Grogan TM, Haddad G, Hipfner DR, Deeley RG, Cole SPC. Standardization of a single-cell assay for sensitive detection of Multidrug Resistance Protein (MRP) expression in normal and malignant cells in archival clinical samples. Journal of Laboratory & Clinical Medicine 1997; 130 (3): 297-306[Medline]. Chen M, Beck WT. Teniposide-resistant CEM cells, which express mutant DNA topoisomerase II alpha, when treated with non-complex-stabilizing inhibitors of the enzyme, display no cross-resistance and reveal aberrant functions of the mutant enzyme. Cancer Research 1993; 53 (24): 5946-5953[Medline]. Chen M, Beck WT. Differences in inhibition of chromosome separation and G2 arrest by DNA topoisomerase II inhibitors merbarone and VM-26. Cancer Research 1995; 55 (7): 1509-1516[Medline]. Chen M, Beck WT. DNA topoisomerase II expression, stability, and phosphorylation in two VM-26-resistant human leukemic CEM sublines. Oncology Research 1995; 7 (2): 103-111[Medline].

Chen ZS, Kawabe T, Ono M, Aoki S, Sumizawa T, Furukawa T, Uchiumi T, Wada M, Kuwano M, Akiyama SI. Effect of multidrug resistance-reversing agents on transporting activity of human canalicular multispecific organic anion transporter. Mol Pharmacol 1999; 56 (6): 1219-1228[Medline]. Chen WS, Luker KE, Dahlheimer JL, Pica CM, Luker GD, Piwnica-Worms D. Effects of MDR1 and MDR3 P-glycoproteins, MRP1, and BCRP/MXR/ABCP on the transport of (99m)Tc-tetrofosmin. Biochem Pharmacol 2000; 60 (3): 413-426[Medline]. Chou TC, Depew KM, Zheng YH, Safer ML, Chan D, Helfrich B, Zatorska D, Zatorski A, Bornmann W, Danishefsky SJ. Reversal of anticancer multidrug resistance by the ardeemins. Proceedings of the National Academy of Sciences of the United States of America 1998; 95 (14): 8369-8374[Medline]. Cleary I, Doherty G, Moran E, Clynes M. The multidrug-resistant human lung tumour cell line, DLKP-A10, expresses novel drug accumulation and sequestration systems. Biochemical Pharmacology 1997; 53 (10): 1493-1502[Medline]. Cole SPC, Campling BG, Louwman IH, Kozbor D, Roder JC. A strategy for the production of human monoclonal antibodies reactive with lung tumor cell lines. Cancer Research 1984; 44 (7): 2750-2753[Medline]. Cole SPC, Campling BG, Atlaw T, Kozbor D, Roder JC. Human monoclonal antibodies. Molecular & Cellular Biochemistry 1984; 62 (2): 109-120[Medline]. Cole SPC, Vreeken EH, Roder JC. Antibody production by human X human hybridomas in serum-free medium. Journal of Immunological Methods 1985; 78 (2): 271-278[Medline]. Cole SPC. Rapid chemosensitivity testing of human lung tumor cells using the MTT assay. Cancer Chemotherapy & Pharmacology 1986; 17 (3): 259-263[Medline]. Cole SPC, Campling BG, Dexter DF, Holden JJ, Roder JC. Establishment of a human large cell lung tumor line (QU-DB) with metastatic properties in athymic mice. Cancer 1986; 58 (4): 917-923[Medline]. Cole SPC, Vreeken EH, Mirski SE, Campling BG. Growth of human x human hybridomas in protein-free medium supplemented with ethanolamine. Journal of Immunological Methods 1987; 97 (1): 29-35[Medline]. Cole SPC, Downes HF, Slovak ML. Effect of calcium antagonists on the chemosensitivity of two multidrug-resistant human tumour cell lines which do not overexpress P-glycoprotein. British Journal of Cancer 1989; 59 (1): 42-46[Medline]. Cole SPC, Mohamdee SA, Mirski SE. A monoclonal antibody detecting cell surface

epitope on some drug resistant human tumour cell lines. British Journal of Cancer 1990; 62 (1): 14-16[Medline]. Cole SPC. Patterns of cross-resistance in a multidrug-resistant small-cell lung carcinoma cell line. Cancer Chemotherapy & Pharmacology 1990; 26 (4): 250-256[Medline]. Cole SPC, Downes HF, Mirski SE, Clements DJ. Alterations in glutathione and glutathione-related enzymes in a multidrug-resistant small cell lung cancer cell line. Molecular Pharmacology 1990; 37 (2): 192-197[Medline]. Cole SPC, Chanda ER, Dicke FP, Gerlach JH, Mirski SE. Non-P-glycoprotein-mediated multidrug resistance in a small cell lung cancer cell line: evidence for decreased susceptibility to drug-induced DNA damage and reduced levels of topoisomerase II. Cancer Research 1991; 51 (13): 3345-3352[Medline]. Cole SPC, Campigotto BM, Johnson JG, Elliott BE. Differential growth inhibition and enhancement of major histocompatibility complex class I antigen expression by interferons in a small-cell lung cancer cell line and its doxorubicin-selected multidrug-resistant variant. Cancer Immunology, Immunotherapy 1991; 33 (4): 274-277[Medline]. Cole SPC, Pinkoski MJ, Bhardwaj G, Deeley RG. Elevated expression of annexin II (lipocortin II, p36) in a multidrug resistant small cell lung cancer cell line. British Journal of Cancer 1992; 65 (4): 498-502[Medline]. Cole SPC. The 1991 Merck Frosst Award. Multidrug resistance in small cell lung cancer. Canadian Journal of Physiology & Pharmacology 1992; 70 (3): 313-329[Medline]. Cole SPC, Bhardwaj G, Gerlach JH, Mackie JE, Grant CE, Almquist KC, Stewart AJ, Kurz EU, Duncan AM, Deeley RG. Overexpression of a transporter gene in a multidrug-resistant human lung cancer cell line. Science 1992; 258 (5088): 1650-1654[Medline]. Cole SPC, Deeley RG. Multidrug resistance-associated protein: sequence correction. Science 1993; 260 (5110): 879[Medline]. Cole SPC, Sparks KE, Fraser K, Loe DW, Grant CE, Wilson GM, Deeley RG. Pharmacological characterization of multidrug resistant MRP-transfected human tumor cells. Cancer Research 1994; 54 (22): 5902-5910[Medline]. Cole SP, Deeley RG. Multidrug resistance associated with overexpression of MRP. Cancer Treatment & Research 1996; 87 39-62[Medline]. Cole SP, Deeley RG. Multidrug resistance mediated by the ATP-binding cassette transporter protein MRP. Bioessays 1998; 20 (11): 931-940[Medline].

Cole SP. Re: Characterization of MOAT-C and MOAT-D, new members of the MRP/cMOAT subfamily of transporter proteins. J Natl Cancer Inst 1999; 91 (10): 888-889[Medline]. Coley HM. Drug resistance studies using fresh human ovarian carcinoma and soft tissue sarcoma samples. Keio Journal of Medicine 1997; 46 (3): 142-147[Medline]. Cui Y, Konig J, Buchholz JK, Spring H, Leier I, Keppler D. Drug resistance and ATP-dependent conjugate transport mediated by the apical multidrug resistance protein, MRP2, permanently expressed in human and canine cells. Mol Pharmacol 1999; 55 (5): 929-937[Medline]. Cui Y, Konig J, Leier I, Buchholz U, Keppler D. Hepatic uptake of bilirubin and its conjugates by the human organic anion transporter SLC21A6. J Biol Chem 2001; 276 (13): 9626-9630[Medline]. Cullen K, Davey R, Davey M. The drug resistance proteins, multidrug resistance-associated protein and P-glycoprotein, do not confer resistance to Fas-induced cell death. Cytometry 2001; 43 (3): 189-194[Medline]. Dahl GV, Grier H, Sikic B, Weinstein H, Arceci R. Multidrug resistance(MDR) reversal utilizing mitoxantrone, etoposide and continuous infusion cyclosporin (MEC) in pediatric ANLL. In: Neth R, eds. Acute leukemia-Prognostic factors and treatment strategies. New York: Springer, 1994: 490[Medline]. Danks MK, Yalowich JC, Beck WT. Atypical multiple drug resistance in a human leukemic cell line selected for resistance to teniposide (VM-26). Cancer Research 1987; 47 (5): 1297-1301[Medline]. Danks MK, Schmidt CA, Deneka DA, Beck WT. Increased ATP requirement for activity of and complex formation by DNA topoisomerase II from human leukemic CCRF-CEM cells selected for resistance to teniposide. Cancer Communications 1989; 1 (2): 101-109[Medline]. Danks MK, Warmoth MR, Friche E, Granzen B, Bugg BY, Harker WG, Zwelling LA, Futscher BW, Suttle DP, Beck WT. Single-strand conformational polymorphism analysis of the M(r) 170,000 isozyme of DNA topoisomerase II in human tumor cells. Cancer Research 1993; 53 (6): 1373-1379[Medline]. Danks MK, Qiu J, Catapano CV, Schmidt CA, Beck WT, Fernandes DJ. Subcellular distribution of the alpha and beta topoisomerase II-DNA complexes stabilized by VM-26. Biochemical Pharmacology 1994; 48 (9): 1785-1795[Medline]. Daoud R, Kast C, Gros P, Georges E. Rhodamine 123 binds to multiple sites in the multidrug resistance protein (MRP1). Biochemistry 2000; 39 (50): 15344-

15352[Medline]. de Jong MC, Slootstra JW, Scheffer GL, Schroeijers AB, Puijk WC, Dinkelberg R, Kool M, Broxterman HJ, Meloen RH, Scheper RJ. Peptide transport by the multidrug resistance protein MRP1. Cancer Res 2001; 61 (6): 2552-2557[Medline]. Dekkers DW, Comfurius P, van Gool RG, Bevers EM, Zwaal RF. Multidrug resistance protein 1 regulates lipid asymmetry in erythrocyte membranes. Biochem J 2000; 350 Pt 2 531-535[Medline]. den Boer ML, Pieters R, Kazemier KM, Rottier MM, Scheper RJ, Flens MJ, Janka G, Veerman AJ. LRP but not P-gp or MRP may cause drug resistance in childhood ALL. Proceedings of the American Association for Cancer Research 1996; 37 Abstract 2174[Medline]. Den Boer ML, Zwaan CM, Pieters R, Kazemier KM, Rottier MM, Flens MJ, Scheper RJ, Veerman AJ. Optimal immunocytochemical and flow cytometric detection of P-gp, MRP and LRP in childhood acute lymphoblastic leukemia. Leukemia 1997; 11 (7): 1078-1085[Medline]. Dingemans AM, van Ark-Otte J, van der Valk P, Apolinario RM, Scheper RJ, Postmus PE, Giaccone G. Expression of the human major vault protein LRP in human lung cancer samples and normal lung tissues. Annals of Oncology 1996; 7 (6): 625-630[Medline]. Dolfini E, Dasdia T, Arancia G, Molinari A, Calcabrini A, Scheper RJ, Flens MJ, Gariboldi MB, Monti E. Characterization of a clonal human colon adenocarcinoma line intrinsically resistant to doxorubicin. British Journal of Cancer 1997; 76 (1): 67-76[Medline]. Doyle LA, Gao Y, Yang W, Ross DD. Characterization of a 95 kilodalton membrane glycoprotein associated with multi-drug resistance. Int J Cancer 1995; 62 (5): 593-598[Medline]. Doyle LA, Ross DD, Sridhara R, Fojo AT, Kaufmann SH, Lee EJ, Schiffer CA. Expression of a 95 kDa membrane protein is associated with low daunorubicin accumulation in leukaemic blast cells. Br J Cancer 1995; 71 (1): 52-58[Medline]. Doyle LA, Yang W, Abruzzo LV, Krogmann T, Gao Y, Rishi AK, Ross DD. A multidrug resistance transporter from human MCF-7 breast cancer cells. Proc Natl Acad Sci U S A 1998; 95 (26): 15665-15670[Medline]. Dufer J, Millot-Broglio C, Oum'Hamed Z, Liautaud-Roger F, Joly P, Desplaces A, Jardillier JC. Nuclear DNA content and chromatin texture in multidrug-resistant human leukemic cell lines. International Journal of Cancer 1995; 60 (1): 108-114[Medline].

el-Deiry WS. Role of oncogenes in resistance and killing by cancer therapeutic agents. Current Opinion in Oncology 1997; 9 (1): 79-87[Medline]. Erlichman C, Boerner SA, Hallgren CG, Spieker R, Wang XY, James CD, Scheffer GL, Maliepaard M, Ross DD, Bible KC, Kaufmann SH. The HER tyrosine kinase inhibitor CI1033 enhances cytotoxicity of 7- ethyl-10-hydroxycamptothecin and topotecan by inhibiting breast cancer resistance protein-mediated drug efflux. Cancer Res 2001; 61 (2): 739-748[Medline]. Evans CD, Mirski SE, Danks MK, Cole SPC. Reduced levels of topoisomerase II alpha and II beta in a multidrug-resistant lung-cancer cell line. Cancer Chemotherapy & Pharmacology 1994; 34 (3): 242-248[Medline]. Feldhoff PW, Mirski SE, Cole SP, Sullivan DM. Altered subcellular distribution of topoisomerase II alpha in a drug-resistant human small cell lung cancer cell line. Cancer Research 1994; 54 (3): 756-762[Medline]. Fernandes DJ, Danks MK, Beck WT. Decreased nuclear matrix DNA topoisomerase II in human leukemia cells resistant to VM-26 and m-AMSA. Biochemistry 1990; 29 (17): 4235-4241[Medline]. Filipits M, Pohl G, Stranzl T, Suchomel RW, Scheper RJ, Jager U, Geissler K, Lechner K, Pirker R. Expression of the lung resistance protein predicts poor outcome in de novo acute myeloid leukemia. Blood 1998; 91 (5): 1508-1513[Medline]. Flens MJ, Scheffer GL, Broxterman HJ, Izquierdo MA, van der Valk P, Scheper RJ. Production of rat monoclonal antibodies recognizing outer cell surface epitopes of novel multidrug resistance-related proteins. Proceedings of the American Association for Cancer Research 1996; 37 Abstract 2145[Medline]. Flens MJ, Scheffer GL, van der Valk P, Broxterman HJ, Eijdems EW, Huysmans AC, Izquierdo MA, Scheper RJ. Identification of novel drug resistance-associated proteins by a panel of rat monoclonal antibodies. International Journal of Cancer 1997; 73 (2): 249-257[Medline]. Friche E, Danks MK, Schmidt CA, Beck WT. Decreased DNA topoisomerase II in daunorubicin-resistant Ehrlich ascites tumor cells. Cancer Research 1991; 51 (16): 4213-4218[Medline]. Gao M, Loe DW, Grant CE, Cole SPC, Deeley RG. Reconstitution of ATP-dependent leukotriene C4 transport by Co-expression of both half-molecules of human multidrug resistance protein in insect cells. Journal of Biological Chemistry 1996; 271 (44): 27782-27787[Medline]. Gao M, Yamazaki M, Loe DW, Westlake CJ, Grant CE, Cole SP, Deeley RG. Multidrug resistance protein. Identification of regions required for active transport of leukotriene

C4. Journal of Biological Chemistry 1998; 273 (17): 10733-10740[Medline]. Gao M, Cui HR, Loe DW, Grant CE, Almquist KC, Cole SP, Deeley RG. Comparison of the functional characteristics of the nucleotide binding domains of multidrug resistance protein 1. J Biol Chem 2000; 275 (17): 13098-13108[Medline]. Gauchez AS, Lunardi J, Pernin C, Marti-Battle D, Fagret D. Detection of chemoresistance profile of cell lines K562, KB, GLC4 and HL60 through characterisation of the hmdr1, mrp and lrp transcripts. In Vivo 2001; 15 (1): 101-104[Medline]. Goto H, Keshelava N, Matthay KK, Lukens JN, Gerbing RB, Stram DO, Seeger RC, Reynolds CP. Multidrug resistance-associated protein 1 (MRP1) expression in neuroblastoma cell lines and primary tumors. Med Pediatr Oncol 2000; 35 (6): 619-622[Medline]. Grandjean F, Bremaud L, Verdier M, Robert J, Ratinaud MH. Sequential gene expression of P-glycoprotein (P-gp), multidrug resistance-associated protein (MRP) and lung resistance protein: functional activity of P-gp and MRP present in the doxorubicin- resistant human K562 cell lines. Anticancer Drugs 2001; 12 (3): 247-258[Medline]. Grant CE, Valdimarsson G, Hipfner DR, Almquist KC, Cole SP, Deeley RG. Overexpression of multidrug resistance-associated protein (MRP) increases resistance to natural product drugs. Cancer Research 1994; 54 (2): 357-361[Medline]. Grant CE, Bhardwaj G, Cole SP, Deeley RG. Cloning, transfer, and characterization of multidrug resistance protein. Methods Enzymol 1998; 292 594-607[Medline]. Granzen B, Graves DE, Baguley BC, Danks MK, Beck WT. Structure-activity studies of amsacrine analogs in drug resistant human leukemia cell lines expressing either altered DNA topoisomerase II or P-glycoprotein. Oncology Research 1992; 4 (11-12): 489-496[Medline]. Gudkov AV, Zelnick CR, Kazarov AR, Thimmapaya R, Suttle DP, Beck WT, Roninson IB. Isolation of genetic suppressor elements, inducing resistance to topoisomerase II-interactive cytotoxic drugs, from human topoisomerase II cDNA. Proceedings of the National Academy of Sciences of the United States of America 1993; 90 (8): 3231-3235[Medline]. Guichard SM, Danks MK. Topoisomerase enzymes as drug targets. Curr Opin Oncol 1999; 11 (6): 482-489[Medline]. Haga S, Hinoshita E, Ikezaki K, Fukui M, Scheffer GL, Uchiumi T, Kuwano M. Involvement of the multidrug resistance protein 3 in drug sensitivity and its expression in human glioma. Jpn J Cancer Res 2001; 92 (2): 211-219[Medline].

Hagen SG, Monroe DG, Dean DM, Sanders MM. Repression of chick multidrug resistance-associated protein 1 (chMRP1) gene expression by estrogen. Gene 2000; 257 (2): 243-249[Medline]. Hagmann W, Nies AT, Konig J, Frey M, Zentgraf H, Keppler D. Purification of the human apical conjugate export pump MRP2 reconstitution and functional characterization as substrate-stimulated ATPase. Eur J Biochem 1999; 265 (1): 281-289[Medline]. Harada T, Nagayama J, Kohno K, Mickley LA, Fojo T, Kuwano M, Wada M. Alu-associated interstitial deletions and chromosomal re-arrangement in 2 human multidrug-resistant cell lines. Int J Cancer 2000; 86 (4): 506-511[Medline]. Harris MJ, Kuwano M, Webb M, Board PG. Identification of the apical membrane targeting signal of the multidrug resistance associated protein 2 (MRP2/cMOAT). J Biol Chem 2001; 27 27[Medline]. Hart SM, Ganeshaguru K, Scheper RJ, Prentice HG, Hoffbrand AV, Mehta AB. Expression of the human major vault protein LRP in acute myeloid leukemia. Experimental Hematology 1997; 25 (12): 1227-1232[Medline]. Hashimoto S, Danks MK, Chatterjee S, Beck WT, Berger NA. A novel point mutation in the 3' flanking region of the DNA-binding domain of topoisomerase II alpha associated with acquired resistance to topoisomerase II active agents. Oncology Research 1995; 7 (1): 21-29[Medline]. Hinoshita E, Uchiumi T, Taguchi K, Kinukawa N, Tsuneyoshi M, Maehara Y, Sugimachi K, Kuwano M. Increased expression of an ATP-binding cassette superfamily transporter, multidrug resistance protein 2, in human colorectal carcinomas. Clin Cancer Res 2000; 6 (6): 2401-2407[Medline]. Hipfner DR, Gauldie SD, Deeley RG, Cole SPC. Detection of the M(r) 190,000 multidrug resistance protein, MRP, with monoclonal antibodies. Cancer Research 1994; 54 (22): 5788-5792[Medline]. Hipfner DR, Almquist KC, Leslie EM, Gerlach JH, Grant CE, Deeley RG, Cole SP. Membrane topology of the multidrug resistance protein (MRP). A study of glycosylation-site mutants reveals an extracytosolic NH2 terminus. Journal of Biological Chemistry 1997; 272 (38): 23623-23630[Medline]. Hipfner DR, Gao M, Scheffer G, Scheper RJ, Deeley RG, Cole SP. Epitope mapping of monoclonal antibodies specific for the 190-kDa multidrug resistance protein (MRP). Br J Cancer 1998; 78 (9): 1134-1140[Medline]. Hipfner DR, Mao Q, Qiu W, Leslie EM, Gao M, Deeley RG, Cole SP. Monoclonal antibodies that inhibit the transport function of the 190- kDa multidrug resistance

protein, MRP. Localization of their epitopes to the nucleotide-binding domains of the protein. J Biol Chem 1999; 274 (22): 15420-15426[Medline]. Hipfner DR, Deeley RG, Cole SP. Structural, mechanistic and clinical aspects of MRP1. Biochim Biophys Acta 1999; 1461 (2): 359-376[Medline]. Hirrlinger J, Konig J, Keppler D, Lindenau J, Schulz JB, Dringen R. The multidrug resistance protein MRP1 mediates the release of glutathione disulfide from rat astrocytes during oxidative stress. J Neurochem 2001; 76 (2): 627-636[Medline]. Hogan TF, Marx JJ, Krawisz BR, Spencer S, Dalton WS, Broxterman HJ, Scheper RJ. The Human Papillary Renal Carcinoma Cell Line Achn Exhibits Broad 'Nonclassic' Multidrug Resistance At Both Low- and High-Passage Levels, and Expresses Lrp56 Antigen But No P-Glycoprotein. Proceedings of the American Association for Cancer Research 1992; 33 A2788[Medline]. Hooijberg JH, Broxterman HJ, Kool M, Assaraf YG, Peters GJ, Noordhuis P, Scheper RJ, Borst P, Pinedo HM, Jansen G. Antifolate resistance mediated by the multidrug resistance proteins MRP1 and MRP2. Cancer Res 1999; 59 (11): 2532-2535[Medline]. Hooijberg JH, Pinedo HM, Vrasdonk C, Priebe W, Lankelma J, Broxterman HJ. The effect of glutathione on the ATPase activity of MRP1 in its natural membranes. FEBS Lett 2000; 469 (1): 47-51[Medline]. Hopper E, Belinsky MG, Zeng H, Tosolini A, Testa JR, Kruh GD. Analysis of the structure and expression pattern of MRP7 (ABCC10), a new member of the MRP subfamily. Cancer Lett 2001; 162 (2): 181-191[Medline]. Hosking LK, Whelan RD, Shellard SA, Davies SL, Hickson ID, Danks MK, Hill BT. Multiple mechanisms of resistance in a series of human testicular teratoma cell lines selected for increasing resistance to etoposide. International Journal of Cancer 1994; 57 (2): 259-267[Medline]. Huang Y, Ibrado AM, Reed JC, Bullock G, Ray S, Tang C, Bhalla K. Co-expression of several molecular mechanisms of multidrug resistance and their significance for paclitaxel cytotoxicity in human AML HL-60 cells. Leukemia 1997; 11 (2): 253-257[Medline]. Hulkower KI, Butler CC, Linebaugh BE, Klaus JL, Keppler D, Giranda VL, Sloane BF. Fluorescent microplate assay for cancer cell-associated cathepsin B. Eur J Biochem 2000; 267 (13): 4165-4170[Medline]. Ishii M, Iwahana M, Mitsui I, Minami M, Imagawa S, Tohgo A, Ejima A. Growth inhibitory effect of a new camptothecin analog, DX-8951f, on various drug-resistant sublines including BCRP-mediated camptothecin derivative-resistant variants derived from the human lung cancer cell line PC-6. Anticancer Drugs 2000; 11 (5): 353-

362[Medline]. Ito Ki K, Olsen SM, Qiu W, Deeley RG, Cole SP. Mutation of a single conserved tryptophan in multidrug resistance protein 1 (MRP1/ABCC1) results in loss of drug resistance and selective loss of organic anion transport. J Biol Chem 2001; 21 21[Medline]. Izquierdo MA, van der Zee AG, Vermorken JB, Belien JA, Giaccone G, Flens MJ, Scheffer G, Kenemans P, Meijer CJ, Pinedo HM, de Vries EG, van der Valk P, Scheper RJ. Prognostic significance of the drug resistance associated protein LRP in advanced ovarian carcinoma. Annals of Oncology 1994; 5 (Suppl 8): 98, Abstract 99[Medline]. Izquierdo MA, Van der Zee AGJ, Vermorken JB, Van der Valk P, Beliën JAM, Giaccone G, Scheffer GL, Flens MJ, Pinedo HM, Kenemans P, Meijer CJLM, De Vries EGE, Scheper RJ. Drug resistance-associated marker LRP for prediction of response to chemotherapy and prognoses in advanced ovarian carcinoma. Journal of the National Cancer Institute 1995; 87 (16): 1230-1237[Medline]. Izquierdo MA, Shoemaker RH, Flens MJ, Scheffer GL, Wu L, Prater TR, Scheper RJ. Overlapping phenotypes of multidrug resistance among disease-oriented panels of human cancer cell lines. Proceedings of the American Association for Cancer Research 1995; 36 Abstract 1923[Medline]. Izquierdo MA, Scheffer GL, Flens MJ, Schroeijers AB, van der Valk P, Scheper RJ. Major vault protein LRP-related multidrug resistance. European Journal of Cancer 1996; 32A (6): 979-984[Medline]. Izquierdo MA, Scheffer GL, Flens MJ, Shoemaker RH, Rome LH, Scheper RJ. Relationship of LRP-human major vault protein to in vitro and clinical resistance to anticancer drugs. Cytotechnology 1996; 19 (3): 191-197[Medline]. Izquierdo MA, Scheffer GL, Flens MJ, Giaccone G, Broxterman HJ, Meijer CJ, van der Valk P, Scheper RJ. Broad distribution of the multidrug resistance-related vault lung resistance protein in normal human tissues and tumors. American Journal of Pathology 1996; 148 (3): 877-887[Medline]. Jedlitschky G, Burchell B, Keppler D. The multidrug resistance protein 5 functions as an ATP-dependent export pump for cyclic nucleotides. J Biol Chem 2000; 275 (39): 30069-30074[Medline]. Jirsch J, Deeley RG, Cole SP, Stewart AJ, Fedida D. Inwardly rectifying K+ channels and volume-regulated anion channels in multidrug-resistant small cell lung cancer cells. Cancer Research 1993; 53 (18): 4156-4160[Medline]. Jonker JW, Smit JW, Brinkhuis RF, Maliepaard M, Beijnen JH, Schellens JH, Schinkel AH. Role of breast cancer resistance protein in the bioavailability and fetal penetration

of topotecan. J Natl Cancer Inst 2000; 92 (20): 1651-1656. Kamisako T, Leier I, Cui Y, Konig J, Buchholz U, Hummel-Eisenbeiss J, Keppler D. Transport of monoglucuronosyl and bisglucuronosyl bilirubin by recombinant human and rat multidrug resistance protein 2. Hepatology 1999; 30 (2): 485-490[Medline]. Kao CH, Tsai SC, Liu TJ, Ho YJ, Wang JJ, Ho ST, ChangLai SP. P-Glycoprotein and multidrug resistance-related protein expressions in relation to technetium-99m methoxyisobutylisonitrile scintimammography findings. Cancer Res 2001; 61 (4): 1412-1414[Medline]. Kawabata S, Oka M, Shiozawa K, Tsukamoto K, Nakatomi K, Soda H, Fukuda M, Ikegami Y, Sugahara K, Yamada Y, Kamihira S, Doyle LA, Ross DD, Kohno S. Breast cancer resistance protein directly confers SN-38 resistance of lung cancer cells. Biochem Biophys Res Commun 2001; 280 (5): 1216-1223[Medline]. Kawabe T, Chen ZS, Wada M, Uchiumi T, Ono M, Akiyama S, Kuwano M. Enhanced transport of anticancer agents and leukotriene C4 by the human canalicular multispecific organic anion transporter (cMOAT/MRP2). FEBS Lett 1999; 456 (2): 327-331[Medline]. Keitel V, Kartenbeck J, Nies AT, Spring H, Brom M, Keppler D. Impaired protein maturation of the conjugate export pump multidrug resistance protein 2 as a consequence of a deletion mutation in Dubin- Johnson syndrome. Hepatology 2000; 32 (6): 1317-1328[Medline]. Kellner U, Hutchinson L, Seidel A, Lage H, Danks MK, Dietel M, Kaufmann SH. Decreased drug accumulation in a mitoxantrone-resistant gastric carcinoma cell line in the absence of P-glycoprotein. International Journal of Cancer 1997; 71 (5): 817-824[Medline]. Keppler D. Export pumps for glutathione S-conjugates. Free Radic Biol Med 1999; 27 (9-10): 985-991[Medline]. Keppler D, Cui Y, Konig J, Leier I, Nies A. Export pumps for anionic conjugates encoded by MRP genes. Adv Enzyme Regul 1999; 39 237-246[Medline]. Keppler D, Kamisako T, Leier I, Cui Y, Nies AT, Tsujii H, Konig J. Localization, substrate specificity, and drug resistance conferred by conjugate export pumps of the MRP family. Adv Enzyme Regul 2000; 40 339-349[Medline]. Keppler D, Konig J. Hepatic secretion of conjugated drugs and endogenous substances. Semin Liver Dis 2000; 20 (3): 265-272[Medline]. Khelifa T, Beck WT. Merbarone, a catalytic inhibitor of DNA topoisomerase II, induces apoptosis in CEM cells through activation of ICE/CED-3-like protease. Mol Pharmacol

1999; 55 (3): 548-556[Medline]. Khelifa T, Beck WT. Induction of apoptosis by dexrazoxane (ICRF-187) through caspases in the absence of c-jun expression and c-Jun NH2-terminal kinase 1 (JNK1) activation in VM-26-resistant CEM cells. Biochem Pharmacol 1999; 58 (8): 1247-1257[Medline]. Kim R, Beck WT. Differences between drug-sensitive and -resistant human leukemic CEM cells in c-jun expression, AP-1 DNA-binding activity, and formation of Jun/Fos family dimers, and their association with internucleosomal DNA ladders after treatment with VM-26. Cancer Research 1994; 54 (18): 4958-4966[Medline]. Komatani H, Kotani H, Hara Y, Nakagawa R, Matsumoto M, Arakawa H, Nishimura S. Identification of breast cancer resistant protein/mitoxantrone resistance/placenta-specific, ATP-binding cassette transporter as a transporter of NB-506 and J-107088, topoisomerase I inhibitors with an indolocarbazole structure. Cancer Res 2001; 61 (7): 2827-2832[Medline]. Konig J, Nies AT, Cui Y, Leier I, Keppler D. Conjugate export pumps of the multidrug resistance protein (MRP) family: localization, substrate specificity, and MRP2-mediated drug resistance. Biochim Biophys Acta 1999; 1461 (2): 377-394[Medline]. Konig J, Rost D, Cui Y, Keppler D. Characterization of the human multidrug resistance protein isoform MRP3 localized to the basolateral hepatocyte membrane. Hepatology 1999; 29 (4): 1156-1163[Medline]. Konig J, Cui Y, Nies AT, Keppler D. A novel human organic anion transporting polypeptide localized to the basolateral hepatocyte membrane. Am J Physiol Gastrointest Liver Physiol 2000; 278 (1): G156-164[Medline]. Konig J, Cui Y, Nies AT, Keppler D. Localization and genomic organization of a new hepatocellular organic anion transporting polypeptide. J Biol Chem 2000; 275 (30): 23161-23168[Medline]. Kool M, van der Linden M, de Haas M, Scheffer GL, de Vree JM, Smith AJ, Jansen G, Peters GJ, Ponne N, Scheper RJ, Elferink RP, Baas F, Borst P. MRP3, an organic anion transporter able to transport anti-cancer drugs. Proc Natl Acad Sci U S A 1999; 96 (12): 6914-6919[Medline]. Kool M, van der Linden M, de Haas M, Baas F, Borst P. Expression of human MRP6, a homologue of the multidrug resistance protein gene MRP1, in tissues and cancer cells. Cancer Res 1999; 59 (1): 175-182[Medline]. Krebes KA, Mirski SE, Pross HF, Cole SP. Peripheral blood mononuclear cells express antigens associated with multidrug resistance in a small cell lung cancer cell line. Anticancer Research 1993; 13 (2): 317-321[Medline].

Kuss BJ, Deeley RG, Cole SPC, Willman CL, Kopecky KJ, Wolman SR, Eyre HJ, Lane SA, Nancarrow JK, Whitmore SA, Callen DF. Deletion of gene for multidrug resistance in acute myeloid leukaemia with inversion in chromosome 16: prognostic implications. Lancet 1994; 343 (8912): 1531-1534[Medline]. Kuss BJ, Deeley RG, Cole SP, Willman CL, Kopecky KJ, Wolman SR, Eyre HJ, Callen DF. The biological significance of the multidrug resistance gene MRP in inversion 16 leukemias. Leukemia & Lymphoma 1996; 20 (5-6): 357-364[Medline]. Kusumoto H, Rodgers QE, Boege F, Raimondi SC, Beck WT. Characterization of novel human leukemic cell lines selected for resistance to merbarone, a catalytic inhibitor of DNA topoisomerase II. Cancer Research 1996; 56 (11): 2573-2583[Medline]. Kuwano M, Toh S, Uchiumi T, Takano H, Kohno K, Wada M. Multidrug resistance-associated protein subfamily transporters and drug resistance. Anticancer Drug Des 1999; 14 (2): 123-131[Medline]. Lang AJ, Mirski SE, Cummings HJ, Yu Q, Gerlach JH, Cole SP. Structural organization of the human TOP2A and TOP2B genes. Gene 1998; 221 (2): 255-266[Medline]. Laupeze B, Amiot L, Payen L, Drenou B, Grosset JM, Lehne G, Fauchet R, Fardel O. Multidrug resistance protein (MRP) activity in normal mature leukocytes and CD34-positive hematopoietic cells from peripheral blood. Life Sci 2001; 68 (11): 1323-1331[Medline]. Laurencot CM, Scheffer GL, Scheper RJ, Shoemaker RH. Mechanisms of LRP and MRP expression in unselected human cancer cell lines exhibiting the MDR phenotype. Proceedings of the American Association for Cancer Research 1996; 37 Abstract 2144[Medline]. Laurencot CM, Scheffer GL, Scheper RJ, Shoemaker RH. Increased LRP mRNA expression is associated with the MDR phenotype in intrinsically resistant human cancer cell lines. International Journal of Cancer 1997; 72 (6): 1021-1026[Medline]. Lautier D, Canitrot Y, Deeley RG, Cole SP. Multidrug resistance mediated by the multidrug resistance protein (MRP) gene. Biochemical Pharmacology 1996; 52 (7): 967-977[Medline]. Leier I, Jedlitschky G, Buchholz U, Cole SP, Deeley RG, Keppler D. The MRP gene encodes an ATP-dependent export pump for leukotriene C4 and structurally related conjugates. Journal of Biological Chemistry 1994; 269 (45): 27807-27810[Medline]. Leier I, Jedlitschky G, Buchholz U, Center M, Cole SP, Deeley RG, Keppler D. ATP-dependent glutathione disulfide transport mediated by the MRP gene-encoded conjugate export pump. Biochemical Journal 1996; 34 (Pt 2): 433-437[Medline].

Leier I, Hummel-Eisenbeiss J, Cui Y, Keppler D. ATP-dependent para-aminohippurate transport by apical multidrug resistance protein MRP2. Kidney Int 2000; 57 (4): 1636-1642[Medline]. Leslie EM, Mao Q, Oleschuk CJ, Deeley RG, Cole SP. Modulation of Multidrug Resistance Protein 1 (MRP1/ABCC1) Transport and ATPase Activities by Interaction with Dietary Flavonoids. Mol Pharmacol 2001; 59 (5): 1171-1180[Medline]. Li XF, Kinuya S, Yokoyama K, Konishi S, Ma YY, Watanabe N, Shuke N, Bunko H, Michigishi T, Tonami N. Technetium-99m-tetrofosmin would be a substrate for multidrug resistance-associated protein (MRP): comparison between a leukemia cell line with high MRP gene expression and its parental cell line. Cancer Biother Radiopharm 2001; 16 (1): 17-23[Medline]. Lin-Lee YC, Tatebe S, Savaraj N, Ishikawa T, Tien Kuo M. Differential sensitivities of the MRP gene family and gamma- glutamylcysteine synthetase to prooxidants in human colorectal carcinoma cell lines with different p53 status. Biochem Pharmacol 2001; 61 (5): 555-563[Medline]. Linn SC, Pinedo HM, van Ark-Otte J, van der Valk P, Hoekman K, Honkoop AH, Vermorken JB, Giaccone G. Expression of drug resistance proteins in breast cancer, in relation to chemotherapy. International Journal of Cancer 1997; 71 (5): 787-795[Medline]. List AF, Spier CS, Grogan TM, Johnson C, Roe DJ, Greer JP, Wolff SN, Broxterman HJ, Scheffer GL, Scheper RJ, Dalton WS. Overexpression of the major vault transporter protein lung-resistance protein predicts treatment outcome in acute myeloid leukemia. Blood 1996; 87 (6): 2464-2469[Medline]. List AF. The role of multidrug resistance and its pharmacological modulation in acute myeloid leukemia. Leukemia 1996; 10 Suppl 1 S36-38. List AF. Role of multidrug resistance and its pharmacological modulation in acute myeloid leukemia. Leukemia 1996; 10 (6): 937-942[Medline]. Litman T, Brangi M, Hudson E, Fetsch P, Abati A, Ross DD, Miyake K, Resau JH, Bates SE. The multidrug-resistant phenotype associated with overexpression of the new ABC half-transporter, MXR (ABCG2). J Cell Sci 2000; 113 (Pt 11): 2011-2021[Medline]. Liu G, Sanchez-Fernandez R, Li ZS, Rea PA. Enhanced multispecificity of arabidopsis vacuolar multidrug resistance- associated protein-type atp-binding cassette transporter, atmrp2. J Biol Chem 2001; 276 (12): 8648-8656[Medline]. Loe DW, Cole SPC, Deeley RG. Biology of drug resistance associated with

overexpression of the multidrug resistance protein, MRP. European Journal of Cancer 1996; 32A (6): 945-957[Medline]. Loe DW, Almquist KC, Cole SPC, Deeley RG. ATP-dependent 17 beta-estradiol 17-(beta-D-glucuronide) transport by multidrug resistance protein (MRP). Inhibition by cholestatic steroids. Journal of Biological Chemistry 1996; 271 (16): 9683-9689[Medline]. Loe DW, Almquist KC, Deeley RG, Cole SPC. Multidrug resistance protein (MRP)-mediated transport of leukotriene C4 and chemotherapeutic agents in membrane vesicles: demonstration of glutathione-dependent vincristine transport. Journal of Biological Chemistry 1996; 271 (16): 9675-9682[Medline]. Loe DW, Deeley RG, Cole SPC. Biology of the multidrug resistance-associated protein, MRP. European Journal of Cancer 1996; 32A (6): 945-957[Medline]. Loe DW, Stewart RK, Massey TE, Deeley RG, Cole SP. ATP-dependent transport of aflatoxin B1 and its glutathione conjugates by the product of the multidrug resistance protein (MRP) gene. Molecular Pharmacology 1997; 51 (6): 1034-1041[Medline]. Loe DW, Deeley RG, Cole SP. Characterization of vincristine transport by the M(r) 190,000 multidrug resistance protein (MRP): evidence for cotransport with reduced glutathione. Cancer Res 1998; 58 (22): 5130-5136[Medline]. Loe DW, Oleschuk CJ, Deeley RG, Cole SP. Structure-activity studies of verapamil analogs that modulate transport of leukotriene C(4) and reduced glutathione by multidrug resistance protein MRP1. Biochem Biophys Res Commun 2000; 275 (3): 795-803[Medline]. Loe DW, Deeley RG, Cole SP. Verapamil stimulates glutathione transport by the 190-kDa multidrug resistance protein 1 (MRP1). J Pharmacol Exp Ther 2000; 293 (2): 530-538[Medline]. Lohoff M, Prechtl S, Sommer F, Roellinghoff M, Schmitt E, Gradehandt G, Rohwer P, Stride BD, Cole SP, Deeley RG. A multidrug-resistance protein (MRP)-like transmembrane pump is highly expressed by resting murine T helper (Th) 2, but not Th1 cells, and is induced to equal expression levels in Th1 and Th2 cells after antigenic stimulation in vivo. J Clin Invest 1998; 101 (3): 703-710[Medline]. Makhey VD, Guo A, Norris DA, Hu P, Yan J, Sinko PJ. Characterization of the regional intestinal kinetics of drug efflux in rat and human intestine and in Caco-2 cells. Pharmaceutical Research 1998; 15 (8): 1160-1167[Medline]. Malayeri R, Filipits M, Suchomel RW, Zochbauer S, Lechner K, Pirker R. Multidrug resistance in leukemias and its reversal. Leukemia & Lymphoma 1996; 23 (5-6): 451-458[Medline].

Maliepaard M, van Gastelen MA, de Jong LA, Pluim D, van Waardenburg RC, Ruevekamp-Helmers MC, Floot BG, Schellens JH. Overexpression of the BCRP/MXR/ABCP gene in a topotecan-selected ovarian tumor cell line. Cancer Res 1999; 59 (18): 4559-4563[Medline]. Maliepaard M, van Gastelen MA, Tohgo A, Hausheer FH, van Waardenburg RC, de Jong LA, Pluim D, Beijnen JH, Schellens JH. Circumvention of Breast Cancer Resistance Protein (BCRP)-mediated Resistance to Camptothecins in Vitro Using Non-Substrate Drugs or the BCRP Inhibitor GF120918. Clin Cancer Res 2001; 7 (4): 935-941[Medline]. Maliepaard M, Scheffer GL, Faneyte IF, van Gastelen MA, Pijnenborg AC, Schinkel AH, van De Vijver MJ, Scheper RJ, Schellens JH. Subcellular localization and distribution of the breast cancer resistance protein transporter in normal human tissues. Cancer Res 2001; 61 (8): 3458-3464[Medline]. Manciu L, Chang XB, Riordan JR, Ruysschaert JM. Multidrug resistance protein MRP1 reconstituted into lipid vesicles: secondary structure and nucleotide-induced tertiary structure changes. Biochemistry 2000; 39 (42): 13026-13033[Medline]. Manciu L, Chang X, Riordan JR, Buyse F, Ruysschaert JM. Nucleotide-induced conformational changes in the human multidrug resistance protein MRP1 are related to the capacity of chemotherapeutic drugs to accumulate or not in resistant cells. FEBS Lett 2001; 493 (1): 31-35[Medline]. Mao Q, Leslie EM, Deeley RG, Cole SP. ATPase activity of purified and reconstituted multidrug resistance protein MRP1 from drug-selected H69AR cells. Biochim Biophys Acta 1999; 1461 (1): 69-82[Medline]. Mao Q, Deeley RG, Cole SP. Functional reconstitution of substrate transport by purified multidrug resistance protein MRP1 (ABCC1) in phospholipid vesicles. J Biol Chem 2000; 275 (44): 34166-34172[Medline]. Marbeuf-Gueye C, Priebe W, Garnier-Suillerot A. Multidrug resistance protein functionality: no effect of intracellular or extracellular pH changes. Biochem Pharmacol 2000; 60 (10): 1485-1489[Medline]. Mariani M, Capolongo L, Suarato A, Bargiotti A, Mongelli N, Grandi M, Beck WT. Growth-inhibitory properties of novel anthracyclines in human leukemic cell lines expressing either Pgp-MDR or at-MDR. Investigational New Drugs 1994; 12 (2): 93-97[Medline]. Michieli M, Damiani D, Ermacora A, Raspadori D, Michelutti A, Grimaz S, Fanin R, Russo D, Lauria F, Masolini P, Baccarani M. P-glycoprotein (PGP) and lung resistance-related protein (LRP) expression and function in leukaemic blast cells. British Journal of

Haematology 1997; 96 (2): 356-365[Medline]. Minderman H, Vanhoefer U, Toth K, Minderman MD, Rustum YM. A unique human ovarian carcinoma cell line expressing CD34 in association with selection for multidrug resistance. Cancer 1996; 78 (11): 2427-2436[Medline]. Mirski SE, Gerlach JH, Cole SPC. Multidrug resistance in a human small cell lung cancer cell line selected in adriamycin. Cancer Research 1987; 47 (10): 2594-2598[Medline]. Mirski SE, Cole SP. Antigens associated with multidrug resistance in H69AR, a small cell lung cancer cell line. Cancer Research 1989; 49 (20): 5719-5724[Medline]. Mirski SEL, Cole SPC. Multidrug resistance-associated antigens on drug-sensitive and -resistant human tumour cell lines. British Journal of Cancer 1991; 64 (1): 15-22[Medline]. Mirski SE, Evans CD, Almquist KC, Slovak ML, Cole SP. Altered topoisomerase II alpha in a drug-resistant small cell lung cancer cell line selected in VP-16. Cancer Research 1993; 53 (20): 4866-4873[Medline]. Mirski SE, Gerlach JH, Cole SP. Sequence determinants of nuclear localization in the alpha and beta isoforms of human topoisomerase II. Exp Cell Res 1999; 251 (2): 329-339[Medline]. Mirski SE, Voskoglou-Nomikos T, Young LC, Deeley RG, Campling BG, Gerlach JH, Cole SP. Simultaneous quantitation of topoisomerase II alpha and beta isoform mRNAs in lung tumor cells and normal and malignant lung tissue. Lab Invest 2000; 80 (6): 787-795[Medline]. Mirski SE, Sparks KE, Yu Q, Lang AJ, Jain N, Campling BG, Cole SP. A truncated cytoplasmic topoisomerase IIalpha in a drug-resistant lung cancer cell line is encoded by a TOP2A allele with a partial deletion of exon 34. Int J Cancer 2000; 85 (4): 534-539[Medline]. Mo YY, Beck WT. Heterogeneous expression of DNA topoisomerase II alpha isoforms in tumor cell lines. Oncology Research 1997; 9 (4): 193-204[Medline]. Mo YY, Wang Q, Beck WT. Down-regulation of topoisomerase IIalpha in CEM cells selected for merbarone resistance is associated with reduced expression of Sp3. Cancer Res 1997; 57 (22): 5004-5008[Medline]. Mo YY, Ameiss KA, Beck WT. Overexpression of human DNA topoisomerase II alpha by fusion to enhanced green fluorescent protein. Biotechniques 1998; 25 (6): 1052-1057[Medline].

Mo YY, Beck WT. Association of human DNA topoisomerase IIalpha with mitotic chromosomes in mammalian cells is independent of its catalytic activity. Exp Cell Res 1999; 252 (1): 50-62[Medline]. Mohri M, Nitta H, Yamashita J. Expression of multidrug resistance-associated protein (MRP) in human gliomas. J Neurooncol 2001; 49 (2): 105-115. Moran E, Cleary I, Larkin AM, Amhlaoibh RN, Masterson A, Scheper RJ, Izquierdo MA, Center M, O'Sullivan F, Clynes M. Co-expression of MDR-associated markers, including P-170, MRP and LRP and cytoskeletal proteins, in three resistant variants of the human ovarian carcinoma cell line, OAW42. European Journal of Cancer 1997; 33 (4): 652-660[Medline]. Morgan SE, Cadena RS, Raimondi SC, Beck WT. Selection of human leukemic CEM cells for resistance to the DNA topoisomerase II catalytic inhibitor ICRF-187 results in increased levels of topoisomerase IIalpha and altered G(2)/M checkpoint and apoptotic responses. Mol Pharmacol 2000; 57 (2): 296-307[Medline]. Morgan SE, Kim R, Wang PC, Bhat UG, Kusumoto H, Lu T, Beck WT. Differences in mutant p53 protein stability and functional activity in teniposide-sensitive and -resistant human leukemic CEM cells. Oncogene 2000; 19 (43): 5010-5019[Medline]. Morgan SE, Beck WT. Role of an inverted CCAAT element in human topoisomerase IIalpha gene expression in ICRF-187-sensitive and -resistant CEM leukemic cells. Mol Pharmacol 2001; 59 (2): 203-211[Medline]. Morrow CS, Smitherman PK, Townsend AJ. Role of multidrug-resistance protein 2 in glutathione S-transferase P1- 1-mediated resistance to 4-nitroquinoline 1-oxide toxicities in HepG2 cells. Mol Carcinog 2000; 29 (3): 170-178[Medline]. Nagayama J, Iino M, Tada Y, Kusaba H, Kiue A, Ohshima K, Kuwano M, Wada M. Retrovirus insertion and transcriptional activation of the multidrug- resistance gene in leukemias treated by a chemotherapeutic agent in vivo. Blood 2001; 97 (3): 759-766[Medline]. Nakagawa M, Emoto A, Nasu N, Hanada T, Kuwano M, Cole SP, Nomura Y. Clinical significance of multi-drug resistance associated protein and P-glycoprotein in patients with bladder cancer. Journal of Urology 1997; 157 (4): 1260-1264[Medline]. Nitiss JL, Beck WT. Antitopoisomerase drug action and resistance. European Journal of Cancer 1996; 32A (6): 958-966[Medline]. Norris MD, Bordow SB, Haber PS, Marshall GM, Kavallaris M, Madafiglio J, Cohn SL, Salwen H, Schmidt ML, Hipfner DR, Cole SP, Deeley RG, Haber M. Evidence that the MYCN oncogene regulates MRP gene expression in neuroblastoma. European Journal of Cancer 1997; 33 (12): 1911-1916[Medline].

O'Neil DA, Cole SP, Martin-Porter E, Housley MP, Liu L, Ganz T, Kagnoff MF. Regulation of human beta-defensins by gastric epithelial cells in response to infection with Helicobacter pylori or stimulation with interleukin-1. Infect Immun 2000; 68 (9): 5412-5415[Medline]. Okumura H, Chen ZS, Sakou M, Sumizawa T, Furukawa T, Komatsu M, Ikeda R, Suzuki H, Hirota K, Aikou T, Akiyama SI. Reversal of P-glycoprotein and multidrug-resistance protein-mediated drug resistance in KB cells by 5-O-benzoylated taxinine K. Mol Pharmacol 2000; 58 (6): 1563-1569[Medline]. Paulusma CC, van Geer MA, Evers R, Heijn M, Ottenhoff R, Borst P, Oude Elferink RP. Canalicular multispecific organic anion transporter/multidrug resistance protein 2 mediates low-affinity transport of reduced glutathione. Biochem J 1999; 338 (Pt 2): 393-401[Medline]. Payen L, Courtois A, Loewert M, Guillouzo A, Fardel O. Reactive oxygen species-related induction of multidrug resistance- associated protein 2 expression in primary hepatocytes exposed to sulforaphane. Biochem Biophys Res Commun 2001; 282 (1): 257-263[Medline]. Payen L, Delugin L, Courtois A, Trinquart Y, Guillouzo A, Fardel O. The sulphonylurea glibenclamide inhibits multidrug resistance protein (MRP1) activity in human lung cancer cells. Br J Pharmacol 2001; 132 (3): 778-784[Medline]. Prechtl S, Roellinghoff M, Scheper R, Cole SP, Deeley RG, Lohoff M. The multidrug resistance protein 1: a functionally important activation marker for murine Th1 cells. J Immunol 2000; 164 (2): 754-761[Medline]. Qian YM, Song WC, Cui H, Cole SP, Deeley RG. Glutathione stimulates sulfated estrogen transport by multidrug resistance protein 1. J Biol Chem 2001; 276 (9): 6404-6411[Medline]. Raaijmakers HG, Izquierdo MA, Lokhorst HM, de Leeuw C, Belien JA, Bloem AC, Dekker AW, Scheper RJ, Sonneveld P. Lung-resistance-related protein expression is a negative predictive factor for response to conventional low but not to intensified dose alkylating chemotherapy in multiple myeloma. Blood 1998; 91 (3): 1029-1036[Medline]. Rabindran SK, Ross DD, Doyle LA, Yang W, Greenberger LM. Fumitremorgin C reverses multidrug resistance in cells transfected with the breast cancer resistance protein. Cancer Res 2000; 60 (1): 47-50[Medline]. Ramachandran C, Melnick SJ. Multidrug resistance in human tumors--molecular diagnosis and clinical significance. Mol Diagn 1999; 4 (2): 81-94[Medline]. Renes J, de Vries EE, Hooiveld GJ, Krikken I, Jansen PL, Muller M. Multidrug

resistance protein MRP1 protects against the toxicity of the major lipid peroxidation product 4-hydroxynonenal. Biochem J 2000; 350 Pt 2 555-561[Medline]. Robey RW, Medina-Perez WY, Nishiyama K, Lahusen T, Miyake K, Litman T, Senderowicz AM, Ross DD, Bates SE. Overexpression of the ATP-binding cassette half-transporter, ABCG2 (Mxr/BCrp/ABCP1), in flavopiridol-resistant human breast cancer cells. Clin Cancer Res 2001; 7 (1): 145-152[Medline]. Rocchi E, Khodjakov A, Volk EL, Yang CH, Litman T, Bates SE, Schneider E. The product of the ABC half-transporter gene ABCG2 (BCRP/MXR/ABCP) is expressed in the plasma membrane. Biochem Biophys Res Commun 2000; 271 (1): 42-46[Medline]. Roder JC, Cole SP, Kozbor D. The EBV-hybridoma technique. Methods in Enzymology 1986; 121 140-167[Medline]. Rosenberg MF, Mao Q, Holzenburg A, Ford RC, Deeley RG, Cole SP. The structure of the multidrug resistance protein 1 (MRP1/ABCC1): crystallization and single-particle analysis. J Biol Chem 2001; 22 22[Medline]. Ross DD, Yang W, Abruzzo LV, Dalton WS, Schneider E, Lage H, Dietel M, Greenberger L, Cole SP, Doyle LA. Atypical multidrug resistance: breast cancer resistance protein messenger RNA expression in mitoxantrone-selected cell lines. J Natl Cancer Inst 1999; 91 (5): 429-433[Medline]. Ross DD, Karp JE, Chen TT, Doyle LA. Expression of breast cancer resistance protein in blast cells from patients with acute leukemia. Blood 2000; 96 (1): 365-368[Medline]. Ross DD. Novel mechanisms of drug resistance in leukemia. Leukemia 2000; 14 (3): 467-473[Medline]. Rost D, Kartenbeck J, Keppler D. Changes in the localization of the rat canalicular conjugate export pump Mrp2 in phalloidin-induced cholestasis. Hepatology 1999; 29 (3): 814-821[Medline]. Ruetz S, Brault M, Kast C, Hemenway C, Heitman J, Grant CE, Cole SP, Deeley RG, Gros P. Functional expression of the multidrug resistance-associated protein in the yeast Saccharomyces cerevisiae. Journal of Biological Chemistry 1996; 271 (8): 4154-4160[Medline]. Ruetz S, Brault M, Kast C, Hemenway C, Heitman J, Grant CE, Cole SP, Deeley RG, Gros P. Functional expression of the multidrug resistance-associated protein in the yeast Saccharomyces cerevisiae. J Biol Chem 1999; 274 (4): 2592[Medline]. Ryu S, Kawabe T, Nada S, Yamaguchi A. Identification of basic residues involved in drug export function of human multidrug resistance-associated protein 2. J Biol Chem 2000; 275 (50): 39617-39624[Medline].

Saito H, Masuda S, Inui K. Cloning and functional characterization of a novel rat organic anion transporter mediating basolateral uptake of methotrexate in the kidney. J Biol Chem 1996; 271 (34): 20719-20725[Medline]. Saito T, Zhang Z, Tokuriki M, Ohtsubo T, Noda I, Shibamori Y, Yamamoto T, Saito H. Expression of multidrug resistance protein 1 (MRP1) in the rat cochlea with special reference to the blood-inner ear barrier. Brain Res 2001; 895 (1-2): 253-257[Medline]. Sasabe H, Tsuji A, Sugiyama Y. Carrier-mediated mechanism for the biliary excretion of the quinolone antibiotic grepafloxacin and its glucuronide in rats. J Pharmacol Exp Ther 1998; 284 (3): 1033-1039[Medline]. Satake S, Sugawara I, Watanabe M, Takami H. Lack of a point mutation of human DNA topoisomerase II in multidrug-resistant anaplastic thyroid carcinoma cell lines. Cancer Letters 1997; 116 (1): 33-39[Medline]. Savas B, Cole SP, Akoglu TF, Pross HF. P-glycoprotein-mediated multidrug resistance and cytotoxic effector cells. Natural Immunity 1992; 11 (4): 177-192[Medline]. Savas B, Cole SP, Tsuruo T, Pross HF. P-glycoprotein-mediated multidrug resistance and lymphokine-activated killer cell susceptibility in ovarian carcinoma. Journal of Clinical Immunology 1996; 16 (6): 348-357[Medline]. Savas B, Kerr PE, Ustun H, Cole SP, Pross HF. Lymphokine-activated killer cell susceptibility and multidrug resistance in small cell lung carcinoma. Anticancer Res 1998; 18 (6A): 4355-4361[Medline]. Saxena M, Henderson GB. MOAT4, a novel multispecific organic-anion transporter for glucuronides and mercapturates in mouse L1210 cells and human erythrocytes. Biochem J 1996; 320 (Pt 1): 273-281[Medline]. Schadendorf D, Makki A, Stahr C, Van Dyck A, Wanner R, Scheffer GL, Flens MJ, Scheper R, Henz BM. Membrane transport proteins associated with drug resistance expressed in human melanoma. American Journal of Pathology 1995; 147 (6): 1545-1552[Medline]. Schaub T, Ishikawa T, Keppler D. ATP-dependent leukotriene export from mastocytoma cells. FEBS Lett 1991; 279 (1): 83-86[Medline]. Schaub TP, Kartenbeck J, Konig J, Vogel O, Witzgall R, Kriz W, Keppler D. Expression of the conjugate export pump encoded by the mrp2 gene in the apical membrane of kidney proximal tubules. J Am Soc Nephrol 1997; 8 (8): 1213-1221[Medline]. Schaub TP, Kartenbeck J, Konig J, Spring H, Dorsam J, Staehler G, Storkel S, Thon WF, Keppler D. Expression of the MRP2 gene-encoded conjugate export pump in

human kidney proximal tubules and in renal cell carcinoma. J Am Soc Nephrol 1999; 10 (6): 1159-1169[Medline]. Scheffer GL, Wijngaard PLJ, Flens MJ, Izquierdo MA, Slovak ML, Pinedo HM, Meijer CJLM, Clevers HC, Scheper RJ. The drug resistance-related protein LRP is the human major vault protein. Nature Medicine 1995; 1 (6): 578-582[Medline]. Scheffer GL, Wijngaard PL, Flens MJ, Izquierdo MA, Slovak ML, Pinedo HM, Meijer CJ, Clevers HC, Scheper RJ. The drug resistance related protein LRP is a major vault protein. Proceedings of the American Association for Cancer Research 1995; 36 Abstract 1921[Medline]. Scheffer GL, Schroeijers AB, Izquierdo MA, Wiemer EA, Scheper RJ. Lung resistance-related protein/major vault protein and vaults in multidrug-resistant cancer. Curr Opin Oncol 2000; 12 (6): 550-556[Medline]. Scheffer GL, Maliepaard M, Pijnenborg AC, van Gastelen MA, de Jong MC, Schroeijers AB, van der Kolk DM, Allen JD, Ross DD, van der Valk P, Dalton WS, Schellens JH, Scheper RJ. Breast cancer resistance protein is localized at the plasma membrane in mitoxantrone- and topotecan-resistant cell lines. Cancer Res 2000; 60 (10): 2589-2593[Medline]. Scheffer GL, Kool M, Heijn M, de Haas M, Pijnenborg AC, Wijnholds J, van Helvoort A, de Jong MC, Hooijberg JH, Mol CA, van der Linden M, de Vree JM, van der Valk P, Elferink RP, Borst P, Scheper RJ. Specific detection of multidrug resistance proteins MRP1, MRP2, MRP3, MRP5, and MDR3 P-glycoprotein with a panel of monoclonal antibodies. Cancer Res 2000; 60 (18): 5269-5277[Medline]. Schellens JH, Maliepaard M, Scheper RJ, Scheffer GL, Jonker JW, Smit JW, Beijnen JH, Schinkel AH. Transport of topoisomerase I inhibitors by the breast cancer resistance protein. Potential clinical implications. Ann N Y Acad Sci 2000; 922 188-194[Medline]. Scheper RJ, Broxterman HJ, Scheffer GL, Meijer CJ, Pinedo HM. Vesicular expression of a 110-kD protein associated with exocytosis of drugs in non-P-glycoprotein MDR tumor cells. Journal of Tumor Marker and Oncology 1991; 6(4) 38[Medline]. Scheper RJ, Broxterman HJ, Scheffer GL, Meijer CJ, Pinedo HM. Drug-transporter proteins in clinical multidrug resistance. Clin Chim Acta 1992; 206 (1-2): 25-32[Medline]. Scheper RJ, Broxterman HJ, Scheffer GL, Kaaijk P, Dalton WS, van Heijningen THM, van Kalken CK, Slovak ML, de Vries EGE, van der Valk P, Meijer CJLM, Pinedo HM. Overexpression of a M(r) 110,000 vesicular protein in non-P-glycoprotein-mediated multidrug resistance. Cancer Research 1993; 53 (7): 1475-1479[Medline].

Schroeijers AB, Scheffer GL, Flens MJ, Meijer GA, Izquierdo MA, van der Valk P, Scheper RJ. Immunohistochemical detection of the human major vault protein LRP with two monoclonal antibodies in formalin-fixed, paraffin-embedded tissues. American Journal of Pathology 1998; 152 (2): 373-378[Medline]. Schultz MJ, Wijnholds J, Peppelenbosch MP, Vervoordeldonk MJ, Speelman P, van Deventer SJ, Borst P, van der Poll T. Mice lacking the multidrug resistance protein 1 are resistant to Streptococcus pneumoniae-Induced pneumonia. J Immunol 2001; 166 (6): 4059-4064. Schuurhuis GJ, Broxterman HJ, Ossenkoppele GJ, Baak JP, Eekman CA, Kuiper CM, Feller N, van Heijningen TH, Klumper E, Pieters R, Pinedo HM. Functional multidrug resistance phenotype associated with combined overexpression of Pgp/MDR1 and MRP together with 1-beta-D-arabinofuranosylcytosine sensitivity may predict clinical response in acute myeloid leukemia. Clinical Cancer Research 1995; 1 (1): 81-93[Medline]. Seitz S, Kretz-Rommel A, Oude Elferink RP, Boelsterli UA. Selective protein adduct formation of diclofenac glucuronide is critically dependent on the rat canalicular conjugate export pump (Mrp2). Chem Res Toxicol 1998; 11 (5): 513-519[Medline]. Sekine T, Watanabe N, Hosoyamada M, Kanai Y, Endou H. Expression cloning and characterization of a novel multispecific organic anion transporter. J Biol Chem 1997; 272 (30): 18526-18529[Medline]. Seppen J, Tada K, Ottenhoff R, Sengupta K, Chowdhury NR, Chowdhury JR, Bosma PJ, Oude Elferink RP. Transplantation of Gunn rats with autologous fibroblasts expressing bilirubin UDP-glucuronosyltransferase: correction of genetic deficiency and tumor formation. Hum Gene Ther 1997; 8 (1): 27-36[Medline]. Shibao K, Takano H, Nakayama Y, Okazaki K, Nagata N, Izumi H, Uchiumi T, Kuwano M, Kohno K, Itoh H. Enhanced coexpression of YB-1 and DNA topoisomerase II alpha genes in human colorectal carcinomas. Int J Cancer 1999; 83 (6): 732-737[Medline]. Silverman JA, Schrenk D. Hepatic canalicular membrane 4: expression of the multidrug resistance genes in the liver. Faseb J 1997; 11 (5): 308-313[Medline]. Sisodiya SM, Lin WR, Squier MV, Thom M. Multidrug-resistance protein 1 in focal cortical dysplasia. Lancet 2001; 357 (9249): 42-43[Medline]. Slovak ML, Mirski SE, Cole SP, Gerlach JH, Yohem KH, Trent JM. Tumourigenic multidrug-resistant HT1080 cells do not overexpress receptors for epidermal growth factor. British Journal of Cancer 1991; 64 (2): 296-298[Medline]. Slovak ML, Ho JP, Bhardwaj G, Kurz EU, Deeley RG, Cole SPC. Localization of a novel multidrug resistance-associated gene in the HT1080/DR4 and H69AR human

tumor cell lines. Cancer Research 1993; 53 (14): 3221-3225[Medline]. Slovak ML, Ho JP, Cole SPC, Deeley RG, Greenberger L, De Vries EGE, Broxterman HJ, Scheffer GL, Scheper RJ. The LRP gene encoding a major vault protein associated with drug resistance maps proximal to MRP on chromosome 16: Evidence that chromosome breakage plays a key role in MRP or LRP gene amplification. Cancer Research 1995; 55 (19): 4214-4219[Medline]. Slovak ML, Ho J, Deeley RG, Cole SP, de Vries EG, Broxterman H, Scheffer GL, Scheper RJ. The drug resistance related protein LRP maps proximal to MRP on the short arm of chromosome 16. Proceedings of the American Association for Cancer Research 1995; 36 Abstract 114[Medline]. Smit JJ, Schinkel AH, Oude Elferink RP, Groen AK, Wagenaar E, van Deemter L, Mol CA, Ottenhoff R, van der Lugt NM, van Roon MA, et al. Homozygous disruption of the murine mdr2 P-glycoprotein gene leads to a complete absence of phospholipid from bile and to liver disease. Cell 1993; 75 (3): 451-462[Medline]. Smith AJ, de Vree JM, Ottenhoff R, Oude Elferink RP, Schinkel AH, Borst P. Hepatocyte-specific expression of the human MDR3 P-glycoprotein gene restores the biliary phosphatidylcholine excretion absent in Mdr2 (-/-) mice. Hepatology 1998; 28 (2): 530-536[Medline]. Sonneveld P, Lokhorst HM, Vossebeld P. Drug resistance in multiple myeloma. Seminars in Hematology 1997; 34 (4 Suppl 5): 34-39[Medline]. Soroka CJ, Lee JM, Azzaroli F, Boyer JL. Cellular localization and up-regulation of multidrug resistance- associated protein 3 in hepatocytes and cholangiocytes during obstructive cholestasis in rat liver. Hepatology 2001; 33 (4): 783-791[Medline]. St-Pierre MV, Serrano MA, Macias RI, Dubs U, Hoechli M, Lauper U, Meier PJ, Marin JJ. Expression of members of the multidrug resistance protein family in human term placenta. Am J Physiol Regul Integr Comp Physiol 2000; 279 (4): R1495-1503[Medline]. Stein U, Walther W, Laurencot CM, Scheffer GL, Scheper RJ, Shoemaker RH. Tumor necrosis factor-alpha and expression of the multidrug resistance-associated genes LRP and MRP. Journal of the National Cancer Institute 1997; 89 (11): 807-813[Medline]. Stein U, Walther W, Lemm M, Naundorf H, Fichtner I. Development and characterisation of novel human multidrug resistant mammary carcinoma lines in vitro and in vivo. International Journal of Cancer 1997; 72 (5): 885-891[Medline]. Stewart AJ, Canitrot Y, Baracchini E, Dean NM, Deeley RG, Cole SP. Reduction of expression of the multidrug resistance protein (MRP) in human tumor cells by antisense phosphorothioate oligonucleotides. Biochemical Pharmacology 1996; 51 (4): 461-

469[Medline]. Stockel B, Konig J, Nies AT, Cui Y, Brom M, Keppler D. Characterization of the 5'-flanking region of the human multidrug resistance protein 2 (MRP2) gene and its regulation in comparison withthe multidrug resistance protein 3 (MRP3) gene. Eur J Biochem 2000; 267 (5): 1347-1358[Medline]. Stride BD, Valdimarsson G, Gerlach JH, Cole SPC, Deeley RG. Structure and expression of the mRNA encoding the murine multidrug resistance protein, an ATP-binding cassette transporter. Molecular Pharmacology 1996; 49 (6): 962-971[Medline]. Stride BD, Grant CE, Loe DW, Hipfner DR, Cole SPC, Deeley RG. Pharmacological characterization of the murine and human orthologs of multidrug-resistance protein in transfected human embryonic kidney cells. Molecular Pharmacology 1997; 52 (3): 344-353[Medline]. Stride BD, Cole SP, Deeley RG. Localization of a substrate specificity domain in the multidrug resistance protein. J Biol Chem 1999; 274 (32): 22877-22883[Medline]. Sugawara I, Akiyama S, Scheper RJ, Itoyama S. Lung resistance protein (LRP) expression in human normal tissues in comparison with that of MDR1 and MRP. Cancer Letters 1997; 112 (1): 23-31[Medline]. Sugawara N, Lai YR, Sugaware C, Arizono K. Decreased hepatobiliary secretion of inorganic mercury, its deposition and toxicity in the Eisai hyperbilirubinemic rat with no hepatic canalicular organic anion transporter. Toxicology 1998; 126 (1): 23-31[Medline]. Sullivan LP, Grantham JJ. Specificity of basolateral organic anion exchanger in proximal tubule for cellular and extracellular solutes. J Am Soc Nephrol 1992; 2 (7): 1192-1200[Medline]. Sullivan GF, Yang JM, Vassil A, Yang J, Bash-Babula J, Hait WN. Response: Modulation of MDR/MRP by wild-type and mutant p53. J Clin Invest 2001; 107 (5): 645-646[Medline]. Sumizawa T, Chuman Y, Sakamoto H, Iemura K, Almquist KC, Deeley RG, Cole SPC, Akiyama S. Non-P-glycoprotein-mediated multidrug-resistant human KB cells selected in medium containing adriamycin, cepharanthine, and mezerein. Somatic Cell & Molecular Genetics 1994; 20 (5): 423-435[Medline]. Sumizawa T, Chuman Y, Sakamoto H, Iemura K, Almquist KC, Deeley RG, Cole SP, Akiyama S. Non-P-glycoprotein-mediated multidrug-resistant human KB cells selected in medium containing adriamycin, cepharanthine, and mezerein. Somat Cell Mol Genet 1994; 20 (5): 423-435[Medline].

Sumizawa T, Chen ZS, Chuman Y, Seto K, Furukawa T, Haraguchi M, Tani A, Shudo N, Akiyama SI. Reversal of multidrug resistance-associated protein-mediated drug resistance by the pyridine analog PAK-104P. Mol Pharmacol 1997; 51 (3): 399-405[Medline]. Suzuki H, Sugiyama Y. Primary active transporter responsible for the biliary excretion of xenobiotics. Seikagaku 1997; 69 (9): 1098-1101[Medline]. Suzuki H, Sugiyama Y. Role of transporters in the detoxification of xenobiotics: recent advances in the study of cMOAT/MRP. Tanpakushitsu Kakusan Koso 1997; 42 (8): 1273-1284[Medline]. Suzuki H, Sugiyama Y. Excretion of GSSG and glutathione conjugates mediated by MRP1 and cMOAT/MRP2. Semin Liver Dis 1998; 18 (4): 359-376[Medline]. Sweet DH, Wolff NA, Pritchard JB. Expression cloning and characterization of ROAT1. The basolateral organic anion transporter in rat kidney. J Biol Chem 1997; 272 (48): 30088-30095[Medline]. Takano H, Ise T, Nomoto M, Kato K, Murakami T, Ohmori H, Imamura T, Nagatani G, Okamoto T, Ohta R, Furukawa M, Shibao K, Izumi H, Kuwano M, Kohno K. Structural and functional analysis of the control region of the human DNA topoisomerase II alpha gene in drug-resistant cells. Anticancer Drug Des 1999; 14 (2): 87-92[Medline]. Takebayashi Y, Nakayama K, Fujioka T, Kanzaki A, Mutho M, Uchida T, Miyazaki K, Ito M, Fukumoto M. Expression of multidrug resistance associated transporters (MDR1, MRP1, LRP and BCRP) in porcine oocyte. Int J Mol Med 2001; 7 (4): 397-400[Medline]. Tan B, Piwnica-Worms D, Ratner L. Multidrug resistance transporters and modulation. Curr Opin Oncol 2000; 12 (5): 450-458[Medline]. Tanaka T, Uchiumi T, Hinoshita E, Inokuchi A, Toh S, Wada M, Takano H, Kohno K, Kuwano M. The human multidrug resistance protein 2 gene: functional characterization of the 5'-flanking region and expression in hepatic cells. Hepatology 1999; 30 (6): 1507-1512[Medline]. Tanaka T, Uchiumi T, Nomoto M, Kohno K, Kondo T, Nishio K, Saijo N, Kuwano M. Cellular balance of glutathione levels through the expression of gamma- glutamylcysteine synthetase and glutathione thiol transferase genes in human hepatic cells resistant to a glutathione poison. Biochim Biophys Acta 1999; 1427 (3): 367-377[Medline]. Taniguchi K, Wada M, Kohno K, Nakamura T, Kawabe T, Kawakami M, Kagotani K, Okumura K, Akiyama S, Kuwano M. A human canalicular multispecific organic anion transporter (cMOAT) gene is overexpressed in cisplatin-resistant human cancer cell

lines with decreased drug accumulation. Cancer Res 1996; 56 (18): 4124-4129[Medline]. Taniguchi K, Kohno K, Kawanami K, Wada M, Kanematsu T, Kuwano M. Drug-induced down-regulation of topoisomerase I in human epidermoid cancer cells resistant to saintopin and camptothecins. Cancer Res 1996; 56 (10): 2348-2354[Medline]. te Boekhorst PA, Lowenberg P, Sonneveld P, Nooter K. P-glycoprotein and CD34 double expression and altered Ara-C metabolism are associated with autonomous proliferation in adult acute myeloid leukemia. Anti-Cancer Drugs 1994; 5 (Suppl 1): 48-49[Medline]. Toh S, Wada M, Uchiumi T, Inokuchi A, Makino Y, Horie Y, Adachi Y, Sakisaka S, Kuwano M. Genomic structure of the canalicular multispecific organic anion- transporter gene (MRP2/cMOAT) and mutations in the ATP-binding-cassette region in Dubin-Johnson syndrome. Am J Hum Genet 1999; 64 (3): 739-746[Medline]. Trauner M. Molecular alterations of canalicular transport systems in experimental models of cholestasis: possible functional correlations. Yale J Biol Med 1997; 70 (4): 365-378[Medline]. Trauner M, Arrese M, Soroka CJ, Ananthanarayanan M, Koeppel TA, Schlosser SF, Suchy FJ, Keppler D, Boyer JL. The rat canalicular conjugate export pump (Mrp2) is down-regulated in intrahepatic and obstructive cholestasis. Gastroenterology 1997; 113 (1): 255-264[Medline]. Tsujii H, Konig J, Rost D, Stockel B, Leuschner U, Keppler D. Exon-intron organization of the human multidrug-resistance protein 2 (MRP2) gene mutated in Dubin-Johnson syndrome. Gastroenterology 1999; 117 (3): 653-660[Medline]. Ubezio P, Limonta M, D'Incalci M, Damia G, Masera G, Giudici G, Wolverton JS, Beck WT. Failure to detect the P-glycoprotein multidrug resistant phenotype in cases of resistant childhood acute lymphocytic leukaemia. European Journal of Cancer & Clinical Oncology 1989; 25 (12): 1895-1899[Medline]. Uchiumi T, Hinoshita E, Haga S, Nakamura T, Tanaka T, Toh S, Furukawa M, Kawabe T, Wada M, Kagotani K, Okumura K, Kohno K, Akiyama S, Kuwano M. Isolation of a novel human canalicular multispecific organic anion transporter, cMOAT2/MRP3, and its expression in cisplatin-resistant cancer cells with decreased ATP-dependent drug transport. Biochem Biophys Res Commun 1998; 252 (1): 103-110[Medline]. Uozaki H, Horiuchi H, Ishida T, Iijima T, Imamura T, Machinami R. Overexpression of resistance-related proteins (metallothioneins, glutathione-S-transferase pi, heat shock protein 27, and lung resistance-related protein) in osteosarcoma. Relationship with poor prognosis. Cancer 1997; 79 (12): 2336-2344[Medline].

van Aubel RA, van Kuijck MA, Koenderink JB, Deen PM, van Os CH, Russel FG. Adenosine triphosphate-dependent transport of anionic conjugates by the rabbit multidrug resistance-associated protein Mrp2 expressed in insect cells. Mol Pharmacol 1998; 53 (6): 1062-1067[Medline]. Van Aubel RA, Peters JG, Masereeuw R, Van Os CH, Russel FG. Multidrug resistance protein mrp2 mediates ATP-dependent transport of classic renal organic anion p-aminohippurate. Am J Physiol Renal Physiol 2000; 279 (4): F713-717[Medline]. van den Heuvel-Eibrink MM, Sonneveld P, Pieters R. The prognostic significance of membrane transport-associated multidrug resistance (MDR) proteins in leukemia. Int J Clin Pharmacol Ther 2000; 38 (3): 94-110[Medline]. van der Kolk DM, de Vries EG, van Putten WJ, Verdonck LF, Ossenkoppele GJ, Verhoef GE, Vellenga E. P-glycoprotein and multidrug resistance protein activities in relation to treatment outcome in acute myeloid leukemia. Clin Cancer Res 2000; 6 (8): 3205-3214[Medline]. van der Kolk DM, de Vries EG, Vellenga E. Deletion of the multidrug resistance protein 1 (MRP1) gene in acute myeloid leukemia patients with inversion 16: expression of MRP1 homologues. Leukemia 2001; 15 (1): 191-192[Medline]. van der Pol JP, Blom DJ, Flens MJ, Luyten GP, de Waard-Siebinga I, Koornneef L, Scheper RJ, Jager MJ. Multidrug resistance-related proteins in primary choroidal melanomas and in vitro cell lines. Investigative Ophthalmology & Visual Science 1997; 38 (12): 2523-2530[Medline]. van Kuijck MA, van Aubel RA, Busch AE, Lang F, Russel FG, Bindels RJ, van Os CH, Deen PM. Molecular cloning and expression of a cyclic AMP-activated chloride conductance regulator: a novel ATP-binding cassette transporter. Proceedings of the National Academy of Sciences of the United States of America 1996; 93 (11): 5401-5406[Medline]. van Kuijck MA, Kool M, Merkx GF, Geurts van Kessel A, Bindels RJ, Deen PM, van Os CH. Assignment of the canalicular multispecific organic anion transporter gene (CMOAT) to human chromosome 10q24 and mouse chromosome 19D2 by fluorescent in situ hybridization. Cytogenetics & Cell Genetics 1997; 77 (3-4): 285-287[Medline]. van Loevezijn A, Allen JD, Schinkel AH, Koomen GJ. Inhibition of BCRP-mediated drug efflux by fumitremorgin-type indolyl diketopiperazines. Bioorg Med Chem Lett 2001; 11 (1): 29-32[Medline]. van Nieuwerk CM, Groen AK, Ottenhoff R, van Wijland M, van den Bergh Weerman MA, Tytgat GN, Offerhaus JJ, Oude Elferink RP. The role of bile salt composition in liver pathology of mdr2 (-/-) mice: differences between males and females. J Hepatol 1997; 26 (1): 138-145[Medline].

Versantvoort CH, Twentyman PR, Barrand MA, Lankelma J, Pinedo HM, Broxterman HJ. Overexpression Of 110- and 190-Kd Proteins In Cancer Cells May Be Involved In Drug-Resistant Phenotype. Proceedings of the American Association for Cancer Research 1992; 33 Abstract 2725[Medline]. Volk EL, Rohde K, Rhee M, McGuire JJ, Doyle LA, Ross DD, Schneider E. Methotrexate cross-resistance in a mitoxantrone-selected multidrug- resistant MCF7 breast cancer cell line is attributable to enhanced energy-dependent drug efflux. Cancer Res 2000; 60 (13): 3514-3521[Medline]. Volm M, Stammler G, Zintl F, Koomagi R, Sauerbrey A. Expression of lung resistance-related protein (LRP) in initial and relapsed childhood acute lymphoblastic leukemia. Anti-Cancer Drugs 1997; 8 (7): 662-665[Medline]. Wada M, Toh S, Taniguchi K, Nakamura T, Uchiumi T, Kohno K, Yoshida I, Kimura A, Sakisaka S, Adachi Y, Kuwano M. Mutations in the canilicular multispecific organic anion transporter (cMOAT) gene, a novel ABC transporter, in patients with hyperbilirubinemia II/Dubin-Johnson syndrome. Hum Mol Genet 1998; 7 (2): 203-207[Medline]. Welters MJ, Fichtinger-Schepman AM, Baan RA, Flens MJ, Scheper RJ, Braakhuis BJ. Role of glutathione, glutathione S-transferases and multidrug resistance-related proteins in cisplatin sensitivity of head and neck cancer cell lines. British Journal of Cancer 1998; 77 (4): 556-561[Medline]. Wessel I, Jensen PB, Falck J, Mirski SE, Cole SP, Sehested M. Loss of amino acids 1490Lys-Ser-Lys1492 in the COOH-terminal region of topoisomerase IIalpha in human small cell lung cancer cells selected for resistance to etoposide results in an extranuclear enzyme localization. Cancer Research 1997; 57 (20): 4451-4454[Medline]. Wijnholds J, Mol CA, van Deemter L, de Haas M, Scheffer GL, Baas F, Beijnen JH, Scheper RJ, Hatse S, De Clercq E, Balzarini J, Borst P. Multidrug-resistance protein 5 is a multispecific organic anion transporter able to transport nucleotide analogs. Proc Natl Acad Sci U S A 2000; 97 (13): 7476-7481[Medline]. Wijnholds J, deLange EC, Scheffer GL, van den Berg DJ, Mol CA, van der Valk M, Schinkel AH, Scheper RJ, Breimer DD, Borst P. Multidrug resistance protein 1 protects the choroid plexus epithelium and contributes to the blood-cerebrospinal fluid barrier. J Clin Invest 2000; 105 (3): 279-285[Medline]. Wolkoff AW. Hepatocellular sinusoidal membrane organic anion transport and transporters. Semin Liver Dis 1996; 16 (2): 121-127[Medline]. Wolverton JS, Danks MK, Schmidt CA, Beck WT. Genetic characterization of the

multidrug-resistant phenotype of VM-26-resistant human leukemic cells. Cancer Research 1989; 49 (9): 2422-2426[Medline]. Wolverton JS, Danks MK, Granzen B, Beck WT. DNA topoisomerase II immunostaining in human leukemia and rhabdomyosarcoma cell lines and their responses to topoisomerase II inhibitors. Cancer Research 1992; 52 (15): 4248-4253[Medline]. Wright SR, Boag AH, Valdimarsson G, Hipfner DR, Campling BG, Cole SP, Deeley RG. Immunohistochemical detection of multidrug resistance protein in human lung cancer and normal lung. Clin Cancer Res 1998; 4 (9): 2279-2289[Medline]. Wyler B, Shao Y, Schneider E, Cianfriglia M, Scheper RJ, Frey BM, Gieseler F, Schmid L, Twentyman PR, Lehnert M. Intermittent exposure to doxorubicin in vitro selects for multifactorial non-P-glycoprotein-associated multidrug resistance in RPMI 8226 human myeloma cells. British Journal of Haematology 1997; 97 (1): 65-75[Medline]. Yamane Y, Furuichi M, Song R, Van NT, Mulcahy RT, Ishikawa T, Kuo MT. Expression of multidrug resistance protein/GS-X pump and gamma- glutamylcysteine synthetase genes is regulated by oxidative stress. J Biol Chem 1998; 273 (47): 31075-31085[Medline]. Yamazaki M, Suzuki H, Hanano M, Tokui T, Komai T, Sugiyama Y. Na(+)-independent multispecific anion transporter mediates active transport of pravastatin into rat liver. Am J Physiol 1993; 264 (1 Pt 1): G36-44[Medline]. Yamazaki M, Akiyama S, Ni'inuma K, Nishigaki R, Sugiyama Y. Biliary excretion of pravastatin in rats: contribution of the excretion pathway mediated by canalicular multispecific organic anion transporter. Drug Metab Dispos 1997; 25 (10): 1123-1129[Medline]. Yanagisawa T, Newman A, Coley H, Renshaw J, Pinkerton CR, Pritchard-Jones K. BIRICODAR (VX-710; Incel): an effective chemosensitizer in neuroblastoma. British Journal of Cancer 1999; 80 (8): 1190-1196[Medline]. Yang CH, Schneider E, Kuo ML, Volk EL, Rocchi E, Chen YC. BCRP/MXR/ABCP expression in topotecan-resistant human breast carcinoma cells. Biochem Pharmacol 2000; 60 (6): 831-837[Medline]. Yokomizo A, Taniguchi K, Hasegawa S, Abe T, Kubo T, Makino Y, Wada M, Kohno K, Kuwano M. Atypical MDR. Gan To Kagaku Ryoho 1994; 21 (8): 1123-1129[Medline]. Young LC, Campling BG, Voskoglou-Nomikos T, Cole SP, Deeley RG, Gerlach JH. Expression of multidrug resistance protein-related genes in lung cancer: correlation with drug response. Clin Cancer Res 1999; 5 (3): 673-680[Medline]. Yu Q, Mirski SE, Sparks KE, Cole SP. Two COOH-terminal truncated cytoplasmic

forms of topoisomerase II alpha in a VP-16-selected lung cancer cell line result from partial gene deletion and alternative splicing. Biochemistry 1997; 36 (19): 5868-5877[Medline]. Zalups RK. Basolateral uptake of mercuric conjugates of N-acetylcysteine and cysteine in the kidney involves the organic anion transport system. J Toxicol Environ Health 1998; 55 (1): 13-29[Medline]. Zaman GJ, Versantvoort CHM, Smit JJM, Eijdems EWHM, de Haas M, Smith AJ, Broxterman HJ, Mulder NH, De Vries EGE, Baas F, Borst P. Analysis of the expression of MRP, the gene for a new putative transmembrane drug transporter, in human multidrug resistant lung cancer cell lines. Cancer Research 1993; 53 (8): 1747-1750[Medline]. Zaman GJ, Flens MJ, van Leusden MR, de Haas M, Mulder HS, Lankelma J, Pinedo HM, Scheper RJ, Baas F, Broxterman HJ, Borst P. The human multidrug resistance-associated protein MRP is a plasma membrane drug-efflux pump. Proceedings of the National Academy of Sciences of the United States of America 1994; 91 (19): 8822-8826[Medline]. Zaman GJ, Lankelma J, van Tellingen O, Beijnen J, Dekker H, Paulusma C, Oude Elferink RP, Baas F, Borst P. Role of glutathione in the export of compounds from cells by the multidrug-resistance-associated protein. Proc Natl Acad Sci U S A 1995; 92 (17): 7690-7694[Medline]. Zaman GJ, Cnubben NH, van Bladeren PJ, Evers R, Borst P. Transport of the glutathione conjugate of ethacrynic acid by the human multidrug resistance protein MRP. FEBS Letters 1996; 391 (1-2): 126-130[Medline]. Zhang DW, Cole SP, Deeley RG. Identification of an amino acid residue in multidrug resistance protein (MRP)1 critical for conferring resistance to anthracyclines. J Biol Chem 2001; 23 23[Medline].