Cancer Hereditario - Investigación en Cancer · 2011. 9. 9. · El riesgo de cáncer de ovario en...
Transcript of Cancer Hereditario - Investigación en Cancer · 2011. 9. 9. · El riesgo de cáncer de ovario en...
CANCER HEREDITARIO
Dr. José MordohMaestría en Biología Molecular Médica
2011
ALFRED KNUDSON
CANCER DE MAMA Y OVARIO HEREDITARIOS
17q2117q21BRCA1BRCA1
MaryMary--Claire King, 1990Claire King, 1990
BCLC: Breast Cancer Linkage ConsortiumBCLC: Breast Cancer Linkage Consortium““The BCLC represents virtually all of the The BCLC represents virtually all of the groups conducting breast cancer linkage groups conducting breast cancer linkage analysis worldwide. The members have analysis worldwide. The members have meeting on a biennal basis since 1989 meeting on a biennal basis since 1989 sharing their linkage results at each sharing their linkage results at each meetingmeeting”” Easton et al, Am J Hum Genet, Easton et al, Am J Hum Genet, 19931993
Mark SkolnickMark SkolnickMyriad Genetics, 1994Myriad Genetics, 1994
2cM2cM
BCLC, 1993BCLC, 1993
Breast cancer tumor suppressor genes
Breast cancer affects 1 in 10 women and represents 31% of cancers in women (~215,990 women diagnosed each year, 2004 estimate).
~5% of breast cancers are hereditary; age of onset for hereditary breast cancer is earlier than other forms (mutations at 2 alleles).
Many genes involved; BRCA1 and BRCA2 are thought to be tumor suppressor genes.
BRCA1 is important for homologous recombination, cellular repairof DNA damage, and transcription of mRNA.
Mutations in BRCA1 also are involved in ovarian cancer.
BRCA2 plays a role in timing of mitosis in the cell cycle.
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CÁNCER DE MAMA Y OVARIO
Breast Cancer Tumor Suppressors
A small proportion of breast cancer is heritable. Two genes are associated with predisposition to developing breast cancer.
BRCA1 on chromosome 17BRCA2 on chromosome 13
Normal function of both is in repair of ds DNA breaks.
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Posibles roles para la proteína BRCA1
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SWI/SNF
Figure 1. Location and Tumor Specificity of the 27 BRCA1 Mutations Identified in Families with Breast Cancer. Exon 1 and the coding region of BRCA1 are depicted, with exons 1, 2, 11, and 24 included for reference. The translation start site is located at the mutation Met1Ile.
Maestría en Biología Molecular Médica –
Dr. José Mordoh 2011
Figure 1. Identification and Location of BRCA2 Mutations That Truncate the Polypeptide Chain. The BRCA2 gene is encoded by 27 exons, the second of which contains the initiator codon (ATG) at nucleotide position 229. The coding sequence spans 10,254 nucleotides, encoding 3418 amino acids. Each truncating mutation results in the insertion of a premature stop codon in the sequence. Detecting these mutations by a protein-truncation assay involves making a complementary DNA copy of the BRCA2 transcript, performing two rounds of nested PCR amplification, and synthesizing messenger RNA and protein in vitro from the PCR-generated templates. Abnormally shortened protein products are created when there is a truncating mutation in one of the two BRCA2 alleles; these products can be detected by electrophoresis.
Maestría en Biología Molecular Médica –
Dr. José Mordoh 2011
Different large BRCA1 rearrangements reported in 20025’
E2 I2 E3 I3 E5 I5E6 I6 E7 I7 E8 I8 E9I9E10I10E11I11E12 I12 E13I13 E14I14E15I15E16I16E17I17E18I18E19 I19 E20I20 E21I21E22I22E23I23E24
3’
I13
14 kb deletion
0.5 kb deletion
14 kb deletion1kb deletion
3 kb deletion24 kb deletion
4 kb deletion
6 kb duplication
? kb deletion
? kb deletion
11 kb deletion
13.2 kb deletion7 kb deletion
5 kb deletion
1 kb deletion
•• Contribution of rearrangements to the spectrum of Contribution of rearrangements to the spectrum of BRCA1BRCA1 mumu-- Dutch families: 36%, Dutch families: 36%, PetrijPetrij--Bosch et al, Nature Genet 1997Bosch et al, Nature Genet 1997-- American families (H Lynch): 15%, American families (H Lynch): 15%, Puget et al, Cancer Res 19Puget et al, Cancer Res 19-- French Families: 10%, French Families: 10%, Gad et al, Gad et al, Oncogene, 2002Oncogene, 2002
11.6 kb deletion
17.2 kb duplication
8.6 kb duplication
> 80 kb deletion
Figure 1. Kaplan–Meier Estimates of the Incidence or Risk of Breast Cancer. Panel A shows the reported incidence of breast cancer among first-degree female relatives of subjects who carried a BRCA1 or BRCA2 mutation and those of subjects who did not. Panel B shows the estimated risk of breast cancer and 95 percent confidence intervals among carriers and noncarriers of a BRCA1 or BRCA2mutation. The difference in risk between the two groups was statistically significant by the age of 35. Panel C shows the estimated risk of breast cancer among carriers of each of the three mutations. The 95 percent confidence intervals are not shown but are about 50 percent wider than the upper curve in Panel B and are widely overlapping.
Maestría en Biología Molecular Médica –
Dr. José M ordoh 2011
Figure 2. Estimates of the Risk of Ovarian Cancer. Panel A shows the estimated risk of ovarian cancer and 95 percent confidence intervals among carriers and noncarriers of BRCA1 or BRCA2 mutations. The differences were statistically significant by the age of 45. Panel B shows the estimated risk of ovarian cancer among carriers of each mutation. Although not shown, the 95 percent confidence intervals are widely overlapping.
Maestría en Biología Molecular Médica –
Dr. José Mordoh 2011
Figure 3. Estimates of the Risk of Prostate Cancer. Panel A shows the estimated risk of prostate cancer and 95 percent confidence intervals among carriers and noncarriers of BRCA1 or BRCA2 mutations. The differences were statistically significant by the age of 67. Panel B shows the estimated risk of prostate cancer among carriers of each mutation. Although not shown, the 95 percent confidence intervals are widely overlapping.
•Any male relatives with breast cancer at any age.
Family History Questionnaire for Breast and Ovarian Cancer
Please place a check mark in the boxes below, for yourself and for each family member who has had cancer as indicated.Breast CancerBefore Age 50
Breast CancerAt or After Age 50
Ovarian CancerAt Any Age
YourselfYour Mother
Your Sister(s)Your Daughter(s)
Mother's Side:Grandmother
Aunt(s)Cousin(s)
Father's Side:Grandmother
Aunt(s)Cousin(s)
Father or Mother's Side: Any Males with breast cancer at any
ageAsk your physician to evaluate your hereditary risk of breast and ovarian cancer if there are:
•Two (2) or more check marks in the above table, OR
•One (1) check mark in the above table and you are of Ashkenazi Jewish descent,
OR
Breast T, 36
Breast, 42Breast T, 45Breast T, 56
Breast T, 40
68 yrs
39 yrs
?
It is needed to identify the responsibleBRCA mutation from the testing of anaffected case to be able to offer an Informative genetic testing in unaffected relatives
Breast T, 341: test of the index case 2: test of a relative
Definition of Penetrance:
Complete Penetrance: Every individual who inherits a mutated gene develops the related disease
Ex: Huntington disease
H h
h h
Ex: BRCA1 Mutation:
B b
b b
Incomplete Penetrance: Less than 100% of the carriers of the mutation develop the disease
100% Incidence of Huntington Disease
100% Normal Individuals
Greater probability of developing breast cancer, but another mutant factor (from environment, other genes) is also needed
May develop sporadic breast cancer
Factors Affecting Penetrance
Hormonal/ reproductive
factors
Modifier genes Carcinogens
Response to DNA damage
Not everyone with an altered gene develops cancer
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“A Genetic Counselor’s Nightmare”
• Many genes control breast cancer– it’s not a Mendelian trait
• Not all mutations in BRCA1 cause cancer• Not all individuals with a mutant BRCA1 allele
develop cancer– BRCA1 is “incompletely penetrant”
Consulta inicial
Sana
Enferma
Hist. Fam. Alto Riesgo
Sin Hist. Fam. Alto Riesgo
Hist. Fam. Alto Riesgo
Sin Hist. Fam. Alto Riesgo
Pariente Enferma
No Disponible
> 50 Años
< 40 Años
> 50 Años
< 40 Años
Test Pariente Test Consulta
+-
-
- -
+
+
-
?
-
?
?
ALGORITMO
Abuelos Paternos del Paciente
Abuelos Maternos del Paciente
PadresTios/as del Pcte.
(Via Materna)Tios/as del Pcte. (Via Paterna)
Hermanos/as del Paciente
PACIENTEESPOSO/A
HIJOS
Referencias:HombreMujerCasamientoCáncerPaciente o Sujeto a Determinar Maestría en Biología
Molecular Médica –Dr. José Mordoh 2011
TIPOS DE BRCA- ANÁLISIS
1- Total: para determinar mutación por primera vez se secuencia todo el gen.
2- Sitio Único: para pacientes con parientes cuya mutación BRCA1/BRCA2 es conocida.
3- Multisitios: para individuos Ashkenazi.Detecta la presencia de mutaciones en tres sitios diferentes.185 del AG, 5382 insC y 6174 del T
Conclusión: en mujeres con mutación BRCA1 o BRCA2,la mastectomía total profiláctica bilateral reduce la incidencia de cáncer de mama luego de 3 años de follow-up.
El riesgo de cáncer de ovario en portadoras de mutacionesBRCA1 o BRCA2, disminuye con cada nacimiento pero nocon duración aumentada de anticonceptivos orales. Es pre-maturo recomendar el uso de anticonceptivos orales paraquimioprevención de cáncer de ovario en portadoras de talesmutaciones
En cáncer de mama con mutaciones en BRCA1 o BRCA2 se expresan grupos de genes diferentes
CANCER DE COLON HEREDITARIO
Adenomatous polyposis coli (APC)
Tumor suppressor gene
First characterized because of its association with familial adenomatous polyposis
Further study proved its role in sporadic cases of colon cancer
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Figure 3. Role of the Cadherins in Establishing Molecular Links between Adjacent Cells. Cadherin dimers gather at adherens junctions to form a zipper-like structure that maintains adjacent cells in close contact. Cadherins are linked to the cytoskeleton through the catenins. These cytoplasmic molecules appear to be essential for normal cadherin function and the formation of adherens junctions. The cadherin itself is linked to -catenin (or related plakoglobin), and -catenin associates with actin microfilaments.
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Dr. José Mordoh 2007
Figure 2. Functional and Pathogenic Properties of APC
Maquinaria de “Mismatch Repair” (MMR)Proteína
Función E-coli Eucariotes
Unión Mismatch MUT S h MSH2h MSH6 (GTBP)
Reclutamiento MUT L h MLH1h PMS1H PMS2
EndonucleaseUnión a DNA hemi- MUT H ?metiladoReparación del gap DNA pol I DNA pol σHelicasa II UVRD ?
MMR: Mismatch RepairGTBP: GT Mismatch Binding ProteinRER+ R li i E P i i MMR
DNA Mismatch Repair Genes
Gene Chromosome Apparent contributionto HNPCC30
hMSH2 2p21-22 31%hMLH1 3p21 33%hPMS1 2q31-33 2%hPMS2 7p22 4%
HNPCC: hereditary nonpolyposis colorectal cancer.
Cancers Usually Result from a Series of Mutations in a Single Cell
Tumor suppressor Tumor suppressorsoncogene
Normal -> proliferating -> benign -> intermed. -> late -> cancerous -> colonepithelium adenoma adenoma adenoma adenoma cancer
with villi
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From Roses,2000
What is Retinoblastoma?
A malignant tumor arising in the undifferentiated retina of one or both eyes during infancy or early childhood.
The most common tumor of the eye in early childhood with a frequency of 4 / 1.000.000 NIÑOS < 15 años
Actually begins to form during fetal development, when retinal cells (retinoblasts) are rapidly dividing.
Expressed by 5 years of age in nearly all cases.
leucocoria
Retinoblastoma
Rare malignant tumor arising from immature neurons in the retinaAbout 25-30 % of cases are associated with a germline mutation, and 70-75 % are sporadic. 5-10% of germline cases are inherited germline mutations20-30% are NEW germline mutations
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RetinoblastomapRb; tumor suppressor
deleted in retinoblastoma plays a pivotol role in mammalian cell cycle represses transcription - E2Fregulated by phosphorylation
-underphosphorylate: growth suppressive-hyperphosphorylated: growth promoting
E2F transcription factors• First described as a DNA binding activity for the
adenovirus early region 2 promoter, so called Early 2 Factor.
• An E2F-binding protein was identified (DP-1). (Girling et al., 1993).
• Several E2F-1 related proteins have been identified.
• Evidence for involvement in cell cycle:1. Overexpression of E2F-1 in NIH3T3 cells
prevents them from entering G0 following growth factor withdrawl.
2. Microinjection of E2F-1 into quiescent NIH3T3 cells stimulated entrance into the cell cycle and DNA synthesis.
Retinoblastoma tumor suppressor gene(Rb)
Mapped to gene chromosome 13 and sequenced.
180 kb; codes a 4.7 kb mRNA that produces a 928 amino acid nuclear phosphoprotein, pRB.
pRB is expressed in every tissue that has been examined and regulates the cell cycle.
Retinoblastoma tumor cells possess point mutations or deletions.
In hereditary retinoblastoma, second RB mutation often is identical to the inherited one (a possible example of gene conversion).
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E2F regulates genes required forS-phase
E2F
DP1
target genes
Target genes: Genes encoding proteins involved in DNA
synthesis-DNA polymerase a-thymidine kinase-thymidylate synthase-ribonucleotide reductase
DNA repair proteins-RAD51
Cell cycle regulators- Cdk2 and cyclins A and E.
E/CDK2
D/CDK4/6
Maestría en Biología Molecular Médica –
Dr. José Mordoh 2011
Retinoblastoma. Microscopía
Maestría en Biología
M olecular Médica –Dr. José M ordoh 2011
Maestría en Biología Molecular Médica –
Dr. José M ordoh 2011
Role of pRB in regulating cell division
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TRATAMIENTOS
– Enucleación– Radioterapia– Laser– Crioterapia– QT con carboplatino
– ¡Se puede curar hasta el 96 % de los niños!
p53
p53 tumor suppressor gene
• 53 kDa nuclear phosphoprotein • the most commonly altered gene
identified in human cancers to date• functions as a tumor suppressor when
normal and a dominant oncogene when mutant
• many mutations result in a prolonged protein half-life and/or overexpression
Maestría en Biología Molecular Médica –
Dr. José M ordoh 2011
Effects of DNA damage and
normal (non-mutant) p53
lead to cell growth arrest.
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p53 Protein
G1 and G2 arrest in cells with damaged DNA depends on the p53 tumor suppressor
Maestría en Biología Molecular Médica –
Dr. José M ordoh 2011
p53 tumor suppressor geneMutations in p53 are implicated in ~50% of human cancers, including cancers of the:
breast, brain, liver, lung, colorectal, bladder, and blood.
Development of tumors requires mutations on two p53 alleles.
Codes a 393 amino acid protein involved in transcription, cell cycle control, DNA repair, and apoptosis (programmed cell death).
p53 binds to several genes, including WAF1, and interacts with at least 17 cellular and viral proteins.
Transgenic mice with deletions of both p53 alleles are viable, but 100% develop cancer by ten months of age.
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