Gal-Yam (Review 2008) - Cancer Epigenetics_ Modifications, Screening and Therapy

8/2/2019 Gal-Yam (Review 2008) - Cancer Epigenetics_ Modifications, Screening and Therapy

http://slidepdf.com/reader/full/gal-yam-review-2008-cancer-epigenetics-modifications-screening-and-therapy 1/17

Cancer Epigenetics: Modifications, Screening,and Therapy

Einav Nili Gal-Yam, Yoshimasa Saito,Gerda Egger, and Peter A. Jones

Department of Urology, Biochemistry and Molecular Biology, USC/NorrisComprehensive Cancer Center, Keck School of Medicine, University of SouthernCalifornia, Los Angeles, California 90089; email: jones [email protected]

Annu. Rev. Med. 2008. 59:267–80

First published online as a Review in Advance onOctober 15, 2007

The Annual Review of Medicine is online athttp://med.annualreviews.org

This article’s doi:10.1146/annurev.med.59.061606.095816

Copyright c 2008 by Annual Reviews. All rights reserved

0066-4219/08/0218-0267$20.00

Key Words

DNA methylation, histone modification, CpG islands

Abstract

Deregulation of gene expression is a hallmark of cancer. Althouggenetic lesions have been thefocus of cancer research for many yea

it has become increasingly recognized that aberrant epigenetic moifications also play major roles in the tumorigenic process. The

modifications are imposed on chromatin, do not change the n

cleotide sequence of DNA, and are manifested by specific patternof gene expression that are heritable through many cell division We review these modifications in normal and cancer cells and t

evolving approaches used to study them. Additionally, we outlinadvances in their potential use for cancer diagnostics and target

epigenetic therapy.

267

Produced with a Trial Version of PDF Annotator - www.PDFAnnotator.com



Exon Exon Repeat

xCancer

Exon RepeatNormal Exon

x

nonmethylated Cytosine

methylated Cytosine

nucleosome

repressive complex (e.g. PcG)

methylated DNA binding proteinH3K4 methyl mark

acetylation mark

H3K9/K27 methyl mark

Cancer

Normal

A

B

Figure 1

Epigenetic patterns in normal and cancer cells. (A) DNA methylation. In normal cells, nearly all of theCpG dinucleotides are methylated whereas CpG islands, mostly residing in 5 regulatory regions of genes, are unmethylated. In cancer cells, many CpG islands become hypermethylated, in conjunction with silencing of their cognate genes, while global hypomethylation, mostly at repetitive elements,occurs. (B) Chromatin and histone modification. Active genes are associated with acetylation of histonetails, methylation of lysine 4 on histone H3 (H3K4), and nucleosome depletion at their promoters. Thepromoters of silenced genes (drawn here in conjunction with DNA hypermethylation) become associated with nucleosomes, lose acetylation and H3K4 methylation marks, and gain repressive methylation markssuch as lysine 9 or 27 on histone H3, which recruit repressive complexes. Methylated DNA bindingproteins link methylated DNA with the histone modification and nucleosome remodeling machineries

(not shown).

considered reversible modifications catalyzedbyenzymeshavingopposingactivities.Ingen-

eral, regions silenced by DNA methylationalso show hypoacetylation and hypermethyla-

tion of specific histone lysine residues, such aslysine 9 or 27 in histone H3 (10). In contrast,

promoters of actively transcribed genes showhyperacetylation of histones H3 and H4, and

methylation of lysine 4 of histone H3 (H3K4)

(11, 12).DNA methylation and histone modifica-

tions function in close interplay with nucleo-some remodeling and positioning complexes

that bind specific histone modifications, suchas trimethylated H3K4 (13, 14) and methyl

CpG binding proteins (15), and move nucle-

osomes on DNA by ATP-dependent mecha-nisms. NonmethylatedCpG islandpromoters

are usually hypersensitive to nucleases and arerelatively depleted of nucleosomes, whereas

methylated promoters have nucleosomes onthem and are nuclease resistant (16, 17, 17a)

(Figure 1B).

CANCER: A MODIFIEDEPIGENOME

When a general role for DNA methylationin gene silencing was established more than

25 years ago (18), it was proposed that aber-rant patterns of DNA methylation might play

a role in tumorigenesis (19). Initial studies

www.annualreviews.org • Cancer Epigenetics 269




MicroRNAs: small,noncoding RNA molecules,approximately 22nucleotides long thatbind to the mRNA

of target genes tonegatively controltheir expression. MicroRNAs haveessential roles innormal developmentand their expressionpatterns are linked tocancer development

Methylomes:Distinct DNA methylation profilesin tumors, tissues, or

different cell types

CpG islandmethylator phenotype (CIMP):a trait exhibited by asubset of tumors thatshow anexceptionally highfrequency of methylation of distinct CpG islands

found evidence for a decrease in the total

5-methylcytosine content in tumor cells (20),

and the occurrence of global hypomethy-lation in cancer was firmly established in

subsequent studies. Hypomethylation occursmainly at DNA repetitive elements and

might contribute to the genomic instability frequently seen in cancer (20). Hypomethyla-

tion might also contribute to overexpressionof oncogenic proteins and was shown to be

associated with loss of imprinting of IGF2

(insulin growth factor 2), leading to aberrant

activation of the normally silent maternally inherited allele. This was found to be associ-

ated with an increased risk for colon cancer

(21). The mechanisms underlying globalhypomethylation patterns are currently

unknown. Aberrant hypermethylation at normally

unmethylated CpG islands occurs parallel toglobal hypomethylation (Figure 1A ). The

CpG island promoter of the Rb ( Retinoblas-

toma) gene, found to be hypermethylated in

retinoblastoma, was the first tumor suppres-sor shown to harbor such a modification (22).

This discovery was soon followed by studiesshowing promoter hypermethylation and si-

lencing of other tumor suppressor genes such

as VHL (von Hippel–Lindau) in renal cancer(23), the cell cycle regulator CDKN2 A/p16 in

bladder cancer (24), the mismatch repair genehMLH1 in colon cancer (25), and many oth-

ers. On the basis of these findings, it was pro-posed that epigenetic silencing of tumor sup-

pressor genes by DNA methylation can serveas an alternative “hit” to mutation and/or

deletion in Knudson’s two-hit carcinogene-sis model (26). This led to the notion that

finding hypermethylated genes would resultin the discovery of new tumor suppressors.

An example is ID4, a proposed tumor sup-

pressor, which was found to be hypermethy-lated in hematological malignancies but for

which no mutations were detected in tumors(27).Thedevelopment of large-scaleunbiased

methodsfordetectingmethylation,suchasre-striction landmark genomic scanning (RLGS)

and array-based techniques (see below), led

to a flurry of studies reporting numerous hy

permethylated genes in cancer (see Referen28 for a partial list). It is now establishe

that aberrant hypermethylation at CpG islanpromoters is a hallmark of cancer. Notabl

not only protein-coding genes undergo the

modifications; CpG island promoters of noncoding microRNAs were shown to be hype

methylated in tumors, possibly contributinto their proposed roles in carcinogenesis (2

30). What is the origin for the deregulate

methylation patterns in cancer? Initially was suggested that like genetic mutations, d

novo hypermethylation events are stochastcally generated, and that the final patterns o

served are a result of growth advantage anselection (30a). However, several observatio

made in recent years should be noted: Firs

hypermethylation events are already appaent at precancerous stages, such as in benig

tumors and in tumor-predisposing inflammtory lesions (31, 32). Second, there seem to b

defined sets of hypermethylated genes in cetain tumors. These differential methylatio

signatures, or “methylomes,” may even diferentiate between tumors of the same type,

was recentlyshown for the CpG island methlator phenotype (CIMP) in colon cancer (33

Third, although many hypermethylated gen

have tumor-suppressing functions, not all ainvolved in cell growth or tumorigenesis. Fu

thermore, some of these genes are not epressed in the corresponding normal tissu

so their methylation does not result in thede novo silencing in the cancer cells (34; E

Nili Gal-Yam, G. Egger, A. Tanay, P. A. Joneunpublished data).

Thus, although the hypothesis of stochatic methylation and selection is probab

true for some cases, the observations detaile

above suggest that these patterns may be generated by upstream-acting “programs” thhave gone wrong. Evidence for such a pro

gram involving the Polycomb group com

plexes (PcGs) is emerging. PcGs are prtein complexes responsible for maintenan

of long-term silencing of genes, which

270 Gal-Yam et al.




mediated by methylation of lysine 27 of his-

tone H3 at therepressed regions. Theenzyme

that catalyzes this modification is EZH2, which is known to be upregulated in tumors

and involved in tumor progression (35). Inembryonic stem cells, repression of a large set

of developmental genes mediated by PcGs isthought to maintain these cells in a pluripo-

tent state (36, 37). Several studies have re-cently shown that these genes are prone to be

hypermethylated in cancer, suggesting a func-tionallink between thetwo repressing systems

and lending support to the idea of an epige-netic stem cell signature in cancer (38–40).

Future studies that analyze global methyla-

tion patterns after manipulation of PcG com-ponents are needed to provide further insights

into the role of this system in aberrant DNA methylation.

As discussed above, silenced hypermethy-lated promoters are generally associated with

hypoacetylation of lysine residues on histonesH3 and H4 and hypermethylation of lysine 9

or lysine 27 on histone H3, which mediate theformation of a repressive chromatin structure

(Figure 1B). Globalhistone modifications arealso altered in cancer: Leukemias, colon can-

cers, and cell lines derived from them exhibit

loss of acetylation at lysine 16 and trimethyla-

tion at lysine 20 of histone H4. These changesseem to occur at hypomethylated repetitive

elements (41). The mechanisms responsible

for alterations of these global patterns aremostly unknown but may involve the dis-

ruption of the enzymes responsible for thesemodifications (28).

DETECTION OF EPIGENETIC MODIFICATIONS

DNA Methylation

Various approaches exist to study DNA

methylation at specific loci (Figure 2). Theoldest approach relies on the use of

methylation-sensitive restriction enzymes(MSREs), which distinguish between methy-

lated and nonmethylated sites. These wereinitially used in conjunction with South-

ern blotting to analyze methylation sta-tus at candidate genes. This technique is

labor-intensive, requires large quantities of high-quality DNA not readily obtained from

tumors, and depends on the existence of theenzymes’ specific recognition sites. Neverthe-

less, MSRE-based techniques are also being

Histone modificationsDNA methylation

Bisulfite Conversion

G GC CT C GA

Bisulfite Treatment

G GT CT T GA

G GU T U GA

PCR

C

methyl group

Restriction

Immunoprecipitation

Sonication

IP

Y YPCR

RNA

Expression

untreated 5-aza-CdR

Reverse Transcription

Chromatin IP (ChIP)

Crosslink, Sonication

IP Y Y

Figure 2

Approaches for detection of epigenetic marks. DNA methylation can be detected by three mainapproaches: one based on bisulfite conversion, which changes the nucleotide sequence depending on themethylation state of cytosines; another based on methylation-sensitive restriction enzymes, whichdifferentially digest methylated and unmethylated DNA; and a third based on pulldown of methylatedDNA by 5-methylcytosine binding proteins. Alternatively, specific activation of genes after treatment with the demethylating agent 5 -aza-2 deoxycytidine identifies potentially methylated genes that need tobe confirmed by direct analyses. Histone modifications are usually detected by chromatinimmunoprecipitation. These approaches, initially used to detect modifications at candidate regions, havealso been adopted for genome-wide studies (see text for details).




Oligonucleotidetiling arrays:microarrays on which overlappingoligonucleotides,usually 25–50 base

pairs long, areprinted, coveringcontiguous regionsof the genome. Usedto interrogateenrichment of genomic regions thatare bound by specificfactors ormodifications

adopted for large-scale analyses, as detailed

below.

Methods based on bisulfite conversionprovide the most accurate methylation de-

tection at the genomic-sequence level. Bisul-fite treatment of DNA results in deamination

of nonmethylated cytosines to uracils whilemethylated cytosinesare not altered (42).This

change in the nucleotide sequence, reflectingthe initial methylation pattern, can be inter-

rogated by various methods. Genomic bisul-fite sequencing, performed after PCR ampli-

fication and cloning of the region of interest,is considered the gold standard for methy-

lated cytosine detection; this method gives

the exact methylation status for each CpGsite. However, because of the large amount

of locus-specific amplification and sequenc-ing involved, this is currently not the pre-

ferred method for high-throughput methy-lation analyses. Methylation-specific PCR

(MSP) or its quantitative derivatives, such as Methyl-light (42a), amplify converted DNA

using primer sets that are specific either forthe methylated or unmethylated DNA (43).

These sensitive techniques have become themost common methylation detectiontoolsus-

ing a candidate gene approach, and they al-

low for the analysis of small quantities of DNA derived from archived tissue. However,

as only totally methylated or totally unmethy-lated molecules are amplified in these tech-

niques, the exact pattern of methylation isnot reflected in the result. Additionally, ow-

ing to their high sensitivity, rigorous negative(unmethylated) and positive (totally methy-

lated) controls should be used. Other meth-ods based on bisulfite-converted DNA, such

as MS-SNuPE or pyrosequencing, have beenadapted from the field of single nucleotide

polymorphism (SNP) detection; these enable

the accurate quantification of methylationat discrete CpG sites within a given region

(44, 45). With the realization that aberrant methy-

lation patterns are common in cancer andthe advent of genomic technologies to de-

tect them, the field has moved from candi-

date gene approaches to methods that d

tect methylation on a large scale in an unbased manner. In restriction landmark genom

scanning (RLGS), the DNA from tumand healthy tissue is cleaved by methylation

sensitive enzymes, radiolabeled, separated b

two-dimensional gel electrophoresis with futherenzyme digestion,andautoradiographe

Comparison between the normal and tumgels reveals spots with differential intensit

representing differential methylation and/ocopy number at specific loci. Although on

∼1000 CpGislands canbe interrogatedin thmanner, this was one of the first techniqu

that compared global methylation profiles a large number of tumor samples, and a non

random and type-specific pattern of promothypermethylation was found in tumors (46)

Methods relying on microarray tech

nologies have further advanced the study genomic methylation. An early example w

the differential methylation hybridizatiomethod (DMH), in which DNA is cleaved b

MSREs, labeled, and hybridized to a CpG iland array. A differential hybridization sign

between normal and tumor DNA reflects diferential methylation at a specific CpG islan

(47). More recently developed techniqurely on the ability of proteins or antibodi

to bind specifically to methylated DNA (449). The methylated DNA immunopr

cipitaion (MeDIP) technique, for exampl

utilizes antibodies that specifically recogni5-methylcytosine to immunoprecipita

methylated DNA, resulting in its enrichmein the sample. Coupling this method wit

oligonucleotide tiling arrays covering thmajority of human promoters (50) or th

complete Arabidopsis thaliana genome (5resulted in the first high-resolution methy

lomes to date and promises to be a powerftool for genome-wide methylation detectio

in various applications. An alternative approach to detect abe

rantly methylated regions relies on the trea

ment of cells with demethylating compounsuch as 5-aza-2 deoxycytidine, which r

sults in the demethylation and transcription

272 Gal-Yam et al.



upregulation of specific genes (52). The use of

these compounds in conjunction with expres-

sion microarrays enables large-scale screeningfor differentially expressed genes in treated

compared to nontreated cells. An advantageof this approach is that it detects function-

ally relevant changes in methylation, whichare assumed to affect the tumorigenic pro-

cess, rather than simply the hypermethyla-tion itself. However, as elevated expression of

a gene after drug treatment could be due toindirect effects of the drug, the actual methy-

lation status of the identified genes needs tobe confirmed by other methods such as those

described above. Another drawback is that the

actual experiments can only be performed oncultured cell lines, which do not necessarily

reflect the situation in the tumors themselves.

HISTONE MODIFICATIONS

The detection of histone modifications largely relies on the existence of high-quality an-

tibodies that recognize specific modificationon various amino acid residues of histones.

Western blots and immunostaining can beused to detect global levels or localization

patterns for these modifications in the nu-

cleus. The now commonly used chromatinimmunoprecipitation (ChIP) technique en-

ables researchers to measure the enrichmentof specific histone modificationsat definedge-

nomic regions. This technique can be scaledto global studies, mainly by combining it with

microarray technology (ChIP-chip). ChIP-chip can be used to study modifications at

defined genomic entities such as promotersor CpG islands, or in contiguous genomic

regions or even whole chromosomes usingrecently developed oligonucleotide tiling ar-

rays. A drawback to ChIP-chip is the inability

to study repetitive elements, as their inclusionin the arrays will interfere with hybridizations

and skew the results. Additionally, a bias may be introduced by the amplification performed

to obtain the large amounts of DNA neededfor hybridizations. ChIP-derived DNA can

also be sequenced, with the number of se-

Chromatin im-munoprecipitatio(ChIP): A commonly usedmethod to detectbinding of histones

modified histones, other factors tospecific genomicregions. Chromatinis cross-linked andsheared followed bpull down withspecific antibodies the histones andtheir bound DNA. This is furtherinterrogated by PCamplification of

specific regions ormicroarray analysis(ChIP-chip)

quence reads aligning to a specific genomic

locus defined as enrichment at this locus (53).

Advantages of this approach are relative easeof analysis, unbiased results, and the fact that

the nucleotide sequence of the pulled downfragments is precisely known. Furthermore,

rapid developments in sequencing techniquesmay eventually render ChIP sequencing

cheaper and more timely than conventionalChIP-chip (54).

EPIGENETIC DIAGNOSTICS

Early detection and risk assessment remain

high priorities in oncology. Ideal tumor mark-

ers would have high sensitivity and specificity and be present in sufficient amounts to re-

veal minimal disease in peripheral samples.Detection of hypermethylated DNA is con-

sidered a promising diagnostic tool in can-cer because aberrant methylation events are

abundant in tumors, occur early in thetumori-genic process, and different cancers exhibit

specific hypermethylation patterns. Becausethey are DNA markers, they are more stable

than RNA or proteins. Furthermore, whereasdetection of other DNA aberrations such as

point mutations often requires examination

of different sites within a gene in variouspatients, promoter hypermethylation usually

occurs over the same region of a given gene,simplifying the design of a detection assay.

During the past decade, many studies havedetected tumor-derived free circulating hy-

permethylatedDNAinplasmaorserumofpa-tients with cancer. Additionally, hypermethy-

lated DNA was obtained from various body fluids of cancer patients, such as urine, stool,

saliva, bronchoalveolar lavage (BAL), sputum,mammary aspiration fluid, pancreatic juice,

peritoneal fluid, and vaginal secretions (55).

Many of these samples can be obtained withminimal invasiveness and thus are suitable

for large population screening. Most of thesestudies were performed using the highly sen-

sitive bisulfite-based MSP methods and provide a basis for future clinical trials using DNA

methylation markers in cancer detection and




DNMTi: DNA methylationinhibitor(s)

surveillance. However, various confounding

issues, such as the specificities of the mark-

ers for the different tumors, need to be clari-fied. For example, many of the markers, such

as RASSF1 and CDKN2A/p16 , appear to bemethylated in various tumors or preneoplas-

tic conditions and are therefore not tumor-specific. Additionally, methods used for sam-

ple collection and methylation detection needto be standardized to achieve sufficient repro-

ducibility of the results. Ideally, one markercould be used for the diagnosis of each tumor

type. In prostate cancer, hypermethylation of

GSTp1 may be promising in that respect (56).

In other cases, highly defined panels of genes

will probably be used for screening. One ex-ample of the latter is a prospective study in

which sputum was collected from individuals who were at high risk for lung cancer but were

cancer-free upon entering the trial. Methy-lation status of six genes predicted the oc-

currence of lung cancer within two years of trial initiation with a specificity and sensitiv-

ity of 65% (57). Although further optimiza-tion of this panel is needed to reach sufficient

sensitivity and specificity, this study providesa proof of concept for the prospective use

of methylation markers in early detection of

cancer.DNA methylation markers can also be

used for disease classification, and to predictprognosis and response to therapy. For in-

stance, methylation of RASSF1A in many tu-mors,including lung,breast, and prostate can-

cers, has been shown to be associated withpoor prognosis (58). In another example, neu-

roblastomas harboring the CIMP phenotype were highly correlated with poor prognosis

(59). Metastatic potential can be predicted onthe basis of the E-cadherin promoter methy-

lation in breast and oral cancers. In terms

of response to therapy, the most compellingexample to date is the hypermethylation of

the MGMT (O6-methylguanine methyltrans-ferase) promoter, whichincreases the sensitiv-

ity of glioblastomas to alkylating agents (60).In addition to the study of single genes,

large-scale techniques are now generating

tumor methylation profiles, or methylome

which can be used for molecular classifi

cation. Furthermore, high-throughput plaforms that can analyze the methylation sta

of a large number of loci in a large numbof samples have been developed. One suc

recently described technology adapts a highthroughput single nucleotide polymorphis

(SNP) genotyping system to detect methyltion based on genotyping bisulfite-converte

DNA (60a). By using this technology, ∼150CpG sites in ∼400 genes from 96 sampl

can be analyzed simultaneously. Studies usinthis technology identified panels of methyl

tion markers that distinguished lung or bla

der cancers from their normal counterparat high specificity (61; G. Liang, E. Wo

P. A. Jones, unpublished results). These panels are promising in terms of their impleme

tation in DNA methylation analyses in largpopulations.

EPIGENETIC THERAPY

Because of their dynamic nature and potenti

reversibility, epigenetic modifications are ap

pealing therapeutic targets in cancer. Variocompounds that alter DNA methylation an

histone modification patterns are currentbeing examined as single agents or in com

bination with other drugs in clinical setting Most DNA methylation inhibito

(DNMTi) that have been clinically testebelong to the nucleoside analog family. The

drugs are converted into deoxynucleotidtriphosphates intracellularly and are inco

porated into replicating DNA in place cytosine. Their main mechanism of actio

is probably through trapping of the methtransferases at sites of nucleoside incorpor

tion (3), which depletes the cells of enzymat

activity, resulting in heritable demethylateDNA. Because incorporation occurs durin

DNA synthesis, only replicating cells ademethylated by DNMTi (62), which ma

confer the preference for highly prolifeating cancer cells. The hypomethylatio

that ensues over the following cell divisio

274 Gal-Yam et al.



reactivates various silenced tumor suppressor

genes, which is proposed to undermine the

antineoplastic properties of the drugs. The prototypes of DNMTi are 5-aza cyti-

dine and 5-aza-2 deoxycytidine. Initially de-scribed as cytotoxic agents (63), they were

later found to cause DNA demethylationand differentiation and to reactivate silenced

genes at much lower doses than those ini-tially used (62). These low doses are now

used, mainly for hematological malignancies,leading to better responses and lower toxic-

ity. Both drugs were recently approved by theU. S. Food and Drug Administration (FDA)

for the treatment of myelodysplastic syn-

drome, a preleukemic disease (64).Zebularine is a new addition to the family

of nucleoside analogs that has demethylatingproperties. The drug can be delivered orally,

is less toxic than the 5-aza analogs, acts prefer-entially on cancer cells, and inhibits polyp for-

mation in female APC/MIN-deficient mice(65; C. Yoo, P. A. Jones, unpublished results).

However, the need for high concentrationsof zebularine and its limited bioavailability

in primates have slowed its advancement intoclinical trials (66).

As discussed above, epigenetic silencing

is tightly coupled with histone deacetylation. Various compounds that inhibit HDACs have

demonstrated antitumor, growth inhibitory,proapoptotic, and prodifferentiation proper-

ties (67). One of the universal targets of HDAC inhibitors (HDACi) is the cell cycle

inhibitor p21, which is consistently upregu-lated by treatment with these drugs in con-

junction with histone hyperacetylation at itspromoter (68). Several silenced proapoptotic

genes, which are members of the death re-ceptor pathway, are also targets of HDACi

treatment in leukemic cells, resulting in their

promoter hyperacetylation and upregulation(69). Notably, tumor cells are almost al-

ways more sensitive to HDACi activity thanhealthy cells (70). It should be emphasized

that in addition to their effects on tran-scription, the antitumoral activity of HDACi

is probably mediated by other mechanisms,

HDACi: histonedeacetylaseinhibitor(s)

such as disruption of higher-order chromatin

structure and DNA repair pathways (67). In

the clinic, many phase I trials show that thesedrugs are well-tolerated, and one of the ini-

tial HDACi, suberoylanilide hydroxamic acid(SAHA), has recently been approved by the

FDA for the treatment of T cell cutaneouslymphoma. More are being developed and

tested in clinical trials for both hematologi-cal and solid tumors (71).

As histone methylation is also a majorplayer in establishing long-term silencing,

drugs targeting the enzymes involved in thismodification are being developed. For ex-

ample, 3-Deazaneplanocin A (DZNep) was

recently shown to deplete Polycomb groupcomponents, inhibit histone H3K27 methyla-

tion, and induce selective apoptotic cell deathin breast cancer cells (72). In another study,

the use of polyamine analogs inhibited the en-zyme that removes the active H3K4 methyla-

tion mark, resulting in upregulation of aber-rantly silenced genes in a cancer cell line (73).

The specificities of these drugs and their po-tential clinical effectiveness need to be care-

fully established in further studies. As the interplay between epigenetic path-

ways is unraveled, the combination of epi-

genetic drugs with each other or with stan-dard chemotherapies has become a focus of

interest. HDACi and DNMTi show synergis-tic effects on transcriptional activation (74),

and initial clinical trials using combinationsof both have been promising (75). Further

randomized trials are needed to prove theirsynergy in patients. Both classes of epige-

netic drugs might sensitize cells to the ac-tion of biological agents such as all-trans

retinoic acid, standard chemotherapeutics,or potential immunotherapies. Clinical tri-

als using these combinations are ongoing

(75).Despite the promise of epigenetic ther-

apy, several concerns remain, mainly stem-ming from the nonspecificity of the drugs. In-

duction of genomic hypomethylation in micecaused chromosome instability and promoted

tumor formation (76, 77), and the question




arises whether the use of hypomethylating

drugs will also have carcinogenic effects. One

study examining this has not found such ef-fects, although the number of patients was

small and the time period short (75). Fur-thermore, in other mouse models, inhibition

of DNMTs prevented tumor development(78). As clinical use of these drugs increases,

these concerns will be answered in the com-ing years. However, the search for more spe-

cific drugs targeting epigenetic modificationsis warranted.

CONCLUDING REMARKS

With the recognition of the role of aberrantepigenetic processes in cancer and the rapid

advent of new technologies to study them,this is an exciting time for the cancer epige-

netics field. National and international col-laborations are forming to launch a human

epigenome project (79). The ultimate aim of this project would be to map all epigenetic

modifications, resulting in a comprehensive

description of these in both normal and di

eased cells. Additionally, a pilot project to th

Cancer Genome Atlas Project was recentlaunched, which aims to systematically e

plore the entire spectrum of genomic changinvolved in human cancer, including epig

netic changes such as DNA methylation (80 The data derived from these projects will b

able to answer questions such as how mangenes are actually affected by epigenetic abe

rations in a given tumor. They will also shefurther light on the underlying mechanism

Although screening using epigenetic markeis a promising prospect, specific and sensitiv

screening panels are yet to be developed an

tested in large prospective clinical studies. is important to directly compare the efficac

of these panels with classic screening procduresand other evolvingscreeningtechniqu

based on proteomics, mRNA expression, omicroRNA arrays. Knowledge of the prev

lence and mechanisms of epigenetic modifications will allow the design of rational inte

vention strategies to target them.

DISCLOSURE STATEMENT

The authors are not aware of any biases that might be perceived as affecting the objectivity

this review.

LITERATURE CITED

1. Bird AP. 1986. CpG-rich islands and the function of DNA methylation. Nature 321:20913

2. Takai D, Jones PA. 2002. Comprehensive analysis of CpG islands in human chromosom21 and 22. Proc. Natl. Acad. Sci. USA 99:3740–45

3. Egger G, Liang G, Aparicio A, et al. 2004. Epigenetics in human disease and prospecfor epigenetic therapy. Nature 429:457–63

4. Eckhardt F, Lewin J, Cortese R, et al. 2006. DNA methylation profiling of human chr

mosomes 6, 20 and 22. Nat. Genet. 38:1378–855. Li E, Bestor TH, Jaenisch R. 1992. Targeted mutation of the DNA methyltransfera

gene results in embryonic lethality. Cell 69:915–266. Okano M, Bell DW, Haber DA, et al. 1999. DNA methyltransferases Dnmt3a an

Dnmt3b are essential for de novo methylation and mammalian development. Cell 99:24757

7. Goll MG, Bestor TH. 2005. Eukaryotic cytosine methyltransferases. Annu. Rev. Biochem

74:481–5148. Nan X, Ng HH, Johnson CA, et al. 1998. Transcriptional repression by the methyl-CpG

binding protein MeCP2 involves a histone deacetylase complex. Nature 393:386–89

276 Gal-Yam et al.



9. Jones PL, Veenstra GJ, Wade PA, et al. 1998. Methylated DNA and MeCP2 recruit

histone deacetylase to repress transcription. Nat. Genet. 19:187–9110. Kouzarides T. 2007. Chromatin modifications and their function. Cell 128:693–70511. Heintzman ND, Stuart RK, Hon G, et al. 2007. Distinct and predictive chromatin sig-

natures of transcriptional promoters and enhancers in the human genome. Nat. Genet.

39:311–1812. Liang G, Lin JC, Wei V, et al. 2004. Distinct localization of histone H3 acetylation and

H3-K4 methylation to the transcription start sites in the human genome. Proc. Natl. Acad.

Sci. USA 101:7357–6213. Li H, Ilin S, Wang W, et al. 2006. Molecular basis for site-specific read-out of histone

H3K4me3 by the BPTF PHD finger of NURF. Nature 442:91–9514. Wysocka J, Swigut T, Xiao H, et al. 2006. A PHD finger of NURF couples histone H3

lysine 4 trimethylation with chromatin remodelling. Nature 442:86–9015. Harikrishnan KN, Chow MZ, Baker EK, et al. 2005. Brahma links the SWI/SNF

chromatin-remodeling complex with MeCP2-dependent transcriptional silencing. Nat.

Genet. 37:254–6416. Tazi J, Bird A. 1990. Alternative chromatin structure at CpG islands. Cell 60:909–2017. Kass SU, Landsberger N, Wolffe AP. 1997. DNA methylation directs a time-dependent

repression of transcription initiation. Curr. Biol. 7:157–65

17a. Lin JC, Jeong S, Liang G, et al. 2007. Role of nucleosomal occupancy in the epigeneticsilencing of the MLH1 CpG island. Cancer Cell 12:432–44

18. Razin A, Riggs AD. 1980. DNA methylation and gene function. Science 210:604–1019. Riggs AD, Jones PA. 1983. 5-methylcytosine, gene regulation, and cancer. Adv. Cancer

Res. 40:1–3020. Feinberg AP, Tycko B. 2004. The history of cancer epigenetics. Nat. Rev. Cancer 4:143–5321. KanedaA, Feinberg AP. 2005. Loss of imprinting of IGF2: a common epigenetic modifier

of intestinal tumor risk. Cancer Res. 65:11236–4022. Greger V, Passarge E, Hopping W, et al. 1989. Epigenetic changes may contribute to

the formation and spontaneous regression of retinoblastoma. Hum. Genet. 83:155–5823. Herman JG, Latif F, Weng Y, et al. 1994. Silencing of the VHL tumor-suppressor gene

by DNA methylation in renal carcinoma. Proc. Natl. Acad. Sci. USA 91:9700–424. Gonzalez-Zulueta M, Bender CM, Yang AS, et al. 1995. Methylation of the 5 CpGisland of the p16/CDKN2 tumor suppressor gene in normal and transformed human

tissues correlates with gene silencing. Cancer Res. 55:4531–3525. Kane MF, Loda M, Gaida GM, et al. 1997. Methylation of the hMLH1 promoter corre-

lates with lack of expression of hMLH1 in sporadic colon tumors and mismatch repair-

defective human tumor cell lines. Cancer Res. 57:808–1126. Jones PA, Laird PW. 1999. Cancer epigenetics comes of age. Nat. Genet. 21:163–6727. Hagiwara K, Nagai H, Li Y, et al. 2007. Frequent DNA methylation but not mutation of

the ID4 gene in malignant lymphoma. J. Clin. Exp. Hematopathol. 47:15–1828. EstellerM. 2007. Cancer epigenomics: DNAmethylomes andhistone-modificationmaps.

Nat. Rev. Genet. 8:286–9829. Saito Y, Liang G, Egger G, et al. 2006. Specific activation of microRNA-127 with down-

regulation of the proto-oncogene BCL6 by chromatin-modifying drugs in human cancercells. Cancer Cell 9:435–43

30. Lujambio A, Ropero S, Ballestar E, et al. 2007. Genetic unmasking of an epigenetically silenced microRNA in human cancer cells. Cancer Res. 67:1424–29

30a. Jones PA, Baylin SB. 2002. The fundamental role of epigenetic events in cancer. Nat. Rev.

Genet. 3:415–28




31. Eads CA, Lord RV, Kurumboor SK, et al. 2000. Fields of aberrant CpG island hyperm

thylation in Barrett’s esophagus and associated adenocarcinoma. Cancer Res. 60:5021–232. Issa JP, Ahuja N, Toyota M, et al. 2001. Accelerated age-related CpG island methylatio

in ulcerative colitis. Cancer Res. 61:3573–7733. Weisenberger DJ, Siegmund KD, Campan M, et al. 2006. CpG island methylator ph

notype underlies sporadic microsatellite instability and is tightly associated with BRAmutation in colorectal cancer. Nat. Genet. 38:787–93

34. Keshet I, Schlesinger Y, Farkash S, et al. 2006. Evidence for an instructive mechanism

de novo methylation in cancer cells. Nat. Genet. 38:149–5335. Varambally S, Dhanasekaran SM, Zhou M, et al. 2002. The polycomb group prote

EZH2 is involved in progression of prostate cancer. Nature 419:624–2936. Lee TI, Jenner RG, Boyer LA, et al. 2006. Control of developmental regulators b

Polycomb in human embryonic stem cells. Cell 125:301–1337. Boyer LA, Plath K, Zeitlinger J, et al. 2006. Polycomb complexes repress development

regulators in murine embryonic stem cells. Nature 441:349–5338. Widschwendter M, Fiegl H, Egle D, et al. 2007. Epigenetic stem cell signature in cance

Nat. Genet. 39:157–5839. Schlesinger Y, Straussman R, Keshet I, et al. 2007. Polycomb-mediated methylation o

Lys27 of histone H3 premarks genes for de novo methylation in cancer. Nat. Gene

39:232–3640. Ohm JE, McGarvey KM, Yu X, et al. 2007. A stem cell-like chromatin pattern ma

predispose tumor suppressor genes to DNA hypermethylation and heritable silencin

Nat. Genet. 39:237–4241. Fraga MF, Ballestar E, Villar-Garea A, et al. 2005. Loss of acetylation at Lys16 an

trimethylation at Lys20 of histone H4 is a common hallmark of human cancer. Na

Genet. 37:391–40042. Clark SJ, Harrison J, Paul CL,Frommer M. 1994. High sensitivity mapping of methylat

cytosines. Nucleic Acids Res. 22:2990–9742a. Eads CA, Danenberg KD, Kawakami K, et al. 2000. MethyLight: a high-throughput ass

to measure DNA methylation. Nucleic Acids Res. 28(8):E32

43. Laird PW. 2003. The power and the promise of DNA methylation markers. Nat. ReCancer 3:253–66

44. Gonzalgo ML, Jones PA. 2002. Quantitative methylation analysis using methylatio

sensitive single-nucleotide primer extension (Ms-SNuPE). Methods 27:128–3345. Colella S, Shen L, Baggerly KA, et al. 2003. Sensitive and quantitative universal Pyros

quencing methylation analysis of CpG sites. Biotechniques 35:146–5046. Costello JF, Fruhwald MC, Smiraglia DJ, et al. 2000. Aberrant CpG-island methylatio

has nonrandom and tumour-type-specific patterns. Nat. Genet. 24:132–3847. Huang TH, Perry MR, Laux DE. 1999. Methylation profiling of CpG islands in hum

breast cancer cells. Hum. Mol. Genet. 8:459–7048. Rauch T, Li H, Wu X, et al. 2006. MIRA-assisted microarray analysis, a new technolo

for the determination of DNA methylation patterns, identifies frequent methylation

homeodomain-containing genes in lung cancer cells. Cancer Res. 66:7939–4749. Weber M, Davies JJ, Wittig D, et al. 2005. Chromosome-wide and promoter-specifi

analyses identify sites of differential DNA methylation in normal and transformed huma

cells. Nat. Genet. 37:853–6250. Weber M, Hellmann I, Stadler MB, et al. 2007. Distribution, silencing potential an

evolutionary impact of promoter DNA methylation in the human genome. Nat. Gen

39:457–66

278 Gal-Yam et al.



51. Zhang X, Yazaki J, Sundaresan A, et al. 2006. Genome-wide high-resolution mapping

and functional analysis of DNA methylation in arabidopsis. Cell 126:1189–20152. Suzuki H, Gabrielson E, Chen W, et al. 2002. A genomic screen for genes upregulated by

demethylation and histone deacetylase inhibition in human colorectal cancer. Nat. Genet.

31:141–4953. Roh TY,Ngau WC,Cui K, et al. 2004. High-resolutiongenome-wide mapping of histone

modifications. Nat. Biotechnol. 22:1013–1654. Barski A, Cuddapah S, Cui K, et al. 2007. High-resolution profiling of histone methyla-

tions in the human genome. Cell 129:823–3755. Laird PW. 2005. Cancer epigenetics. Hum. Mol. Genet. 14(Spec. No. 1):R65–7656. Dobosy JR, Roberts JL, Fu VX, et al. 2007. The expanding role of epigenetics in the

development, diagnosis and treatmentof prostate cancer and benign prostatic hyperplasia. J. Urol. 177:822–31

57. Belinsky SA, Liechty KC, GentryFD, et al. 2006. Promoter hypermethylation of multiple

genes in sputumprecedeslung cancerincidence in a high-risk cohort. CancerRes. 66:3338–44

58. Hesson LB, Cooper WN, Latif F. 2007. The role of RASSF1A methylation in cancer.Dis. Markers 23:73–87

59. Abe M, Westermann F, Nakagawara A, et al. 2007. Marked and independent prognostic

significance of the CpG island methylator phenotype in neuroblastomas. Cancer Lett.247:253–58

60. Esteller M, Garcia-Foncillas J, Andion E, et al. 2000. Inactivation of the DNA-repairgene MGMT and the clinical response of gliomas to alkylating agents. N. Engl. J. Med.

343:1350–5460a. Fan JB, Gunderson KL, Bibikova M, et al. 2006. Illlumina universal bead arrays. Methods

Enzymol. 410:57–7361. Bibikova M, Lin Z, Zhou L, et al. 2006. High-throughput DNA methylation profiling

using universal bead arrays. Genome Res. 16:383–9362. Constantinides PG, Jones PA, Gevers W. 1977. Functional striated muscle cells from

nonmyoblast precursors following 5-azacytidine treatment. Nature 267:364–66

63. Sorm F, Piskala A, Cihak A, et al.1964.5-Azacytidine,a new, highlyeffective cancerostatic. Experientia 20:202–3

64. Kantarjian H, Oki Y, Garcia-Manero G, et al. 2007. Results of a randomized study of 3

schedules of low-dose decitabine in higher-risk myelodysplastic syndrome and chronicmyelomonocytic leukemia. Blood 109:52–57

65. Cheng JC, Yoo CB, Weisenberger DJ, et al. 2004. Preferential response of cancer cells

to zebularine. Cancer Cell 6:151–5866. Yoo CB, Jones PA. 2006. Epigenetic therapy of cancer: past, present and future. Nat. Rev.

Drug Discov. 5:37–5067. Minucci S, Pelicci PG. 2006. Histone deacetylase inhibitors and the promise of epigenetic

(and more) treatments for cancer. Nat. Rev. Cancer 6:38–5168. Richon VM, Sandhoff TW, Rifkind RA, et al. 2000. Histone deacetylase inhibitor selec-

tively induces p21WAF1 expression and gene-associated histone acetylation. Proc. Natl.

Acad. Sci. USA 97:10014–1969. Insinga A, Monestiroli S, Ronzoni S, et al. 2005. Inhibitors of histone deacetylases induce

tumor-selective apoptosis through activation of the death receptor pathway. Nat. Med.

11:71–7670. Johnstone RW. 2002. Histone-deacetylase inhibitors: novel drugs for the treatment of

cancer. Nat. Rev. Drug Discov. 1:287–99




71. Bolden JE, Peart MJ, Johnstone RW. 2006. Anticancer activities of histone deacetyla

inhibitors. Nat. Rev. Drug Discov. 5:769–84

72. Tan J, Yang X, Zhuang L, et al. 2007. Pharmacologic disruption of Polycomb-repressivcomplex 2-mediated gene repression selectively induces apoptosis in cancer cells. Gen

Dev. 21:1050–6373. Huang Y, Greene E, Murray Stewart T, et al. 2007. Inhibition of lysine-specific demeth

lase 1 by polyamine analogues results in reexpression of aberrantly silenced genes. Pro

Natl. Acad. Sci. USA 104:8023–28

74. Cameron EE, Bachman KE, Myohanen S, et al. 1999. Synergy of demethylation anhistone deacetylase inhibition in the re-expression of genes silenced in cancer. Nat. Gen

21:103–775. Issa JP. 2007. DNA methylation as a therapeutic target in cancer. Clin. Cancer Re

13:1634–3776. Gaudet F, Hodgson JG, Eden A, et al. 2003. Induction of tumors in mice by genom

hypomethylation. Science 300:489–92

77. Eden A, Gaudet F, Waghmare A, et al. 2003. Chromosomal instability and tumors prmoted by DNA hypomethylation. Science 300:455

78. Laird PW, Jackson-Grusby L, Fazeli A, et al. 1995. Suppression of intestinal neoplasby DNA hypomethylation. Cell 81:197–205

79. Jones PA, Martienssen R. 2005. A blueprint for a Human Epigenome Project: the AACHuman Epigenome Workshop. Cancer Res. 65:11241–46

80. Collins FS, Barker AD. 2007. Mapping the cancer genome. Pinpointing the genes in volved in cancer will help chart a new course across the complex landscape of huma

malignancies. Sci. Am. 296:50–57

280 Gal-Yam et al.



Annual Review of

Medicine

Volume 59, 2008Contents

The FDA Critical Path Initiative and Its Influence on New Drug

Development

Janet Woodcock and Raymond Woosley p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p1

Reversing Advanced Heart Failure by Targeting Ca2+ Cycling

David M. Kaye, Masahiko Hoshijima, and Kenneth R. Chien p p p p p p p p p p p p p p p p p p p p p p p p 13

Tissue Factor and Factor VIIa as Therapeutic Targets in

Disorders of HemostasisUlla Hedner and Mirella Ezban p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 29

Therapy of Marfan Syndrome

Daniel P. Judge and Harry C. Dietz p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 43

Preeclampsia and Angiogenic Imbalance

Sharon Maynard, Franklin H. Epstein, and S. Ananth Karumanchi p p p p p p p p p p p p p p p p p 61

Management of Lipids in the Prevention of Cardiovascular Events

Helene Glassberg and Daniel J. Rader p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 79

Genetic Susceptibility to Type 2 Diabetes and Implications for Antidiabetic Therapy

Allan F. Moore and Jose C. Florez p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 95

Array-Based DNA Diagnostics: Let the Revolution Begin

Arthur L. Beaudet and John W. Belmont p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 113

Inherited Mitochondrial Diseases of DNA Replication

William C. Copeland p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 131

Childhood Obesity: Adrift in the “Limbic Triangle”

Michele L. Mietus-Snyder and Robert H. Lustig p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 147

Expanded Newborn Screening: Implications for Genomic Medicine

Linda L. McCabe and Edward R.B. McCabe p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 163

Is Human Hibernation Possible?

Cheng Chi Lee p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 177

Advance Directives

Linda L. Emanuel p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 187

v

http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.med.59.090506.155819









































































Genetic Determinants of Aggressive Breast Cancer

Alejandra C. Ventura and Sofia D. Merajver p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 19

A Role for JAK2 Mutations in Myeloproliferative Diseases

Kelly J. Morgan and D. Gary Gilliland p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 21

Appropriate Use of Cervical Cancer Vaccine

Gregory D. Zimet, Marcia L. Shew, and Jessica A. Kahn p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 22

A Decade of Rituximab: Improving Survival Outcomes in

Non-Hodgkin’s Lymphoma

Arturo Molina p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 23

Nanotechnology and Cancer

James R. Heath and Mark E. Davis p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 25

Cancer Epigenetics: Modifications, Screening, and Therapy

Einav Nili Gal-Yam, Yoshimasa Saito, Gerda Egger, and Peter A. Jones p p p p p p p p p p p p 26

T Cells and NKT Cells in the Pathogenesis of Asthma

Everett H. Meyer, Rosemarie H. DeKruyff, and Dale T. Umetsup p p p p p p p p p p p p p p p p p p p

28Complement Regulatory Genes and Hemolytic Uremic Syndromes

David Kavanagh, Anna Richards, and John Atkinson p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 29

Mesenchymal Stem Cells in Acute Kidney Injury

Benjamin D. Humphreys and Joseph V. Bonventre p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 31

Asthma Genetics: From Linear to Multifactorial Approaches

Stefano Guerra and Fernando D. Martinez p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 32

The Effect of Toll-Like Receptors and Toll-Like Receptor Genetics in

Human Disease

Stavros Garantziotis, John W. Hollingsworth, Aimee K. Zaas,

and David A. Schwartz p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 34

Advances in Antifungal Therapy

Carole A. Sable, Kim M. Strohmaier, and Jeffrey A. Chodakewitz p p p p p p p p p p p p p p p p p p 36

Herpes Simplex: Insights on Pathogenesis and Possible Vaccines

David M. Koelle and Lawrence Corey p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p38

Medical Management of Influenza Infection

Anne Moscona p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 39

Bacterial and Fungal Biofilm Infections A. Simon Lynch and Gregory T. Robertson p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 41

EGFR Tyrosine Kinase Inhibitors in Lung Cancer: An Evolving Story

Lecia V. Sequist and Thomas J. Lynch p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p42

Adaptive Treatment Strategies in Chronic Disease

Philip W. Lavori and Ree Dawson p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 44

vi C on te nt s



























































































Antiretroviral Drug–Based Microbicides to Prevent HIV-1 Sexual

Transmission

Per Johan Klasse, Robin Shattock, and John P. Moore p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 455

The Challenge of Hepatitis C in the HIV-Infected Person

David L. Thomas p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 473

Hide-and-Seek: The Challenge of Viral Persistence in HIV-1 Infection

Luc Geeraert, Günter Kraus, and Roger J. Pomerantzp p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p

487

Advancements in the Treatment of Epilepsy

B.A. Leeman and A.J. Cole p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 503

Indexes

Cumulative Index of Contributing Authors, Volumes 55–59 p p p p p p p p p p p p p p p p p p p p p p p p 525

Cumulative Index of Chapter Titles, Volumes 55–59 p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p 529

Errata

An online log of corrections to Annual Review of Medicine articles may be found at

http://med.annualreviews.org/errata.shtml
























Gal-Yam (Review 2008) - Cancer Epigenetics_ Modifications, Screening and Therapy

Documents

Transcript of Gal-Yam (Review 2008) - Cancer Epigenetics_ Modifications, Screening and Therapy