Yael Laitman

Common Breast Cancer-Predisposition Alleles Are Associated with Breast Cancer Risk in BRCA1 and BRCA2 Mutation Carriers

Germline mutations in BRCA1 and BRCA2 confer high risks of breast cancer. However, evidence suggests that these risks are modified by other genetic or environmental factors that cluster in families. A recent genome-wide association study has shown that common alleles at single nucleotide polymorphisms (SNPs) in FGFR2 (rs2981582), TNRC9 (rs3803662), and MAP3K1 (rs889312) are associated with increased breast cancer risks in the general population. To investigate whether these loci are also associated with breast cancer risk in BRCA1 and BRCA2 mutation carriers, we genotyped these SNPs in a sample of 10,358 mutation carriers from 23 studies. The minor alleles of SNP rs2981582 and rs889312 were each associated with increased breast cancer risk in BRCA2 mutation carriers (per-allele hazard ratio [HR] = 1.32, 95% CI: 1.20-1.45, p(trend) = 1.7 x 10(-8) and HR = 1.12, 95% CI: 1.02-1.24, p(trend) = 0.02) but not in BRCA1 carriers. rs3803662 was associated with increased breast cancer risk in both BRCA1 and BRCA2 mutation carriers (per-allele HR = 1.13, 95% CI: 1.06-1.20, p(trend) = 5 x 10(-5) in BRCA1 and BRCA2 combined). These loci appear to interact multiplicatively on breast cancer risk in BRCA2 mutation carriers. The differences in the effects of the FGFR2 and MAP3K1 SNPs between BRCA1 and BRCA2 carriers point to differences in the biology of BRCA1 and BRCA2 breast cancer tumors and confirm the distinct nature of breast cancer in BRCA1 mutation carriers.

Genome-wide association study identifies a common variant in RAD51B associated with male breast cancer risk

We conducted a genome-wide association study of male breast cancer comprising 823 cases and 2,795 controls of European ancestry, with validation in independent sample sets totaling 438 cases and 474 controls. A SNP in RAD51B at 14q24.1 was significantly associated with male breast cancer risk (P = 3.02 × 10−13; odds ratio (OR) = 1.57). We also refine association at 16q12.1 to a SNP within TOX3 (P = 3.87 × 10−15; OR = 1.50).

The leucine rich repeat kinase 2 (LRRK2) G2019S substitution mutation. Association with Parkinson disease, malignant melanoma and prevalence in ethnic groups in Israel.

BackgroundA single missense mutation (G2019S) in the leucine rich repeat kinase 2 (LRRK2) gene has been reported to be prevalent among Ashkenazi Jewish patients with Parkinson disease (PD). An association between malignant melanoma (MM) and PD was also recently reported. The nature of this association is still elusive.ObjectiveTo evaluate the rate of the G2019S* LRKK2 mutation among ethnically diverse, Jewish PD patients, MM patients, and Ashkenazi, Iraqi and Moroccan healthy controls.Patients and methodsOverall, 242 Jewish PD patients (155 Ashkenazim and 7 of mixed origin) and 169 Jewish MM patients (142 Ashkenazim) were genotyped for the G2019S mutation. In addition, 900 healthy ethnic Jewish controls (300 Ashkenazim, 300 Moroccans and 300 Iraqis) were similarly analyzed. Genotyping was performed using PCR amplification followed by restriction digest and gel electrophoresis. Statistical analysis was done using the Chi square test.ResultsOverall 19/242 (7.9 %) of the PD patients (16/155 of Ashkenazim, 10.3 %; 3/87 of non-Ashkenazim, 3.4 %) harbored the G2019S LRKK2 mutation. The age at diagnosis of PD in mutation carriers was 60.6 ± 10.9 years compared with an age at diagnosis of 61.1 ± 13.4 years in non-carriers (p = 0.87). Nine of 38 familial Ashkenazi PD patients (23.68 %) carried the mutation, as did 2/169 MM patients (1.2 %; 2/142, 1.4 % of the Ashkenazim). A single mutation carrier of Ashkenazi origin was detected among 900 controls (0.3 % of the Ashkenazi controls).ConclusionThe G2019S*LRKK2 mutation is significantly more prevalent in Ashkenazi PD patients than in controls (p = 1 × 10–6), it is less commonly detected in non-Ashkenazi affected individuals, and its contribution to MM predisposition in Jewish individuals needs to be explored further.

Modification of BRCA1-associated breast and ovarian cancer risk by BRCA1-interacting genes

Inherited BRCA1 mutations confer elevated cancer risk. Recent studies have identified genes that encode proteins that interact with BRCA1 as modifiers of BRCA1-associated breast cancer. We evaluated a comprehensive set of genes that encode most known BRCA1 interactors to evaluate the role of these genes as modifiers of cancer risk. A cohort of 2,825 BRCA1 mutation carriers was used to evaluate the association of haplotypes at ATM, BRCC36, BRCC45 (BRE), BRIP1 (BACH1/FANCJ), CTIP, ABRA1 (FAM175A), MERIT40, MRE11A, NBS1, PALB2 (FANCN), RAD50, RAD51, RAP80, and TOPBP1, and was associated with time to breast and ovarian cancer diagnosis. Statistically significant false discovery rate (FDR) adjusted P values for overall association of haplotypes (P(FDR)) with breast cancer were identified at ATM (P(FDR) = 0.029), BRCC45 (P(FDR) = 0.019), BRIP1 (P(FDR) = 0.008), CTIP (P(FDR) = 0.017), MERIT40 (P(FDR) = 0.019), NBS1 (P(FDR) = 0.003), RAD50 (P(FDR) = 0.014), and TOPBP1 (P(FDR) = 0.011). Haplotypes at ABRA1 (P(FDR) = 0.007), BRCC45 (P(FDR) = 0.016 and P(FDR) = 0.005 in two haplotype blocks), and RAP80 (P(FDR) < 0.001) were associated with ovarian cancer risk. Overall, the data suggest that genomic variation at multiple loci that encode proteins that interact biologically with BRCA1 are associated with modified breast cancer and ovarian cancer risk in women who carry BRCA1 mutations.

Functional variant of KLOTHO: a breast cancer risk modifier among BRCA1 mutation carriers of Ashkenazi origin.

Klotho is a transmembrane protein that can be shed and act as a circulating hormone and is a putative tumor suppressor in breast cancer. A functional variant of KLOTHO (KL-VS) contains two amino acid substitutions F352V and C370S and shows reduced activity. Germ-line mutations in BRCA1 and BRCA2 substantially increase lifetime risk of breast and ovarian cancers. Yet, penetrance of deleterious BRCA1 and BRCA2 mutations is incomplete even among carriers of identical mutations. We examined the association between KL-VS and cancer risk among 1115 Ashkenazi Jewish women: 236 non-carriers, 631 BRCA1 (185delAG, 5382insC) carriers and 248 BRCA2 (6174delT) carriers. Among BRCA1 carriers, heterozygosity for the KL-VS allele was associated with increased breast and ovarian cancer risk (hazard ratio 1.40, 95% confidence intervals 1.08–1.83, P=0.01) and younger age at breast cancer diagnosis (median age 48 vs 43 P=0.04). KLOTHO and BRCA2 are located on 13q12, and we identified linkage disequilibrium between KL-VS and BRCA2 6174delT mutation. Studies in breast cancer cells showed reduced growth inhibitory activity and reduced secretion of klotho F352V compared with wild-type klotho. These data suggest KL-VS as a breast and ovarian cancer risk modifier among BRCA1 mutation carriers. If validated in additional cohorts, the presence of KL-VS may serve as a predictor of cancer risk among BRCA1 mutation carriers.

Association of the Variants CASP8 D302H and CASP10 V410I with Breast and Ovarian Cancer Risk in BRCA1 and BRCA2 Mutation Carriers

Background: The genes caspase-8 (CASP8) and caspase-10 (CASP10) functionally cooperate and play a key role in the initiation of apoptosis. Suppression of apoptosis is one of the major mechanisms underlying the origin and progression of cancer. Previous case-control studies have indicated that the polymorphisms CASP8 D302H and CASP10 V410I are associated with a reduced risk of breast cancer in the general population. Methods: To evaluate whether the CASP8 D302H (CASP10 V410I) polymorphisms modify breast or ovarian cancer risk in BRCA1 and BRCA2 mutation carriers, we analyzed 7,353 (7,227) subjects of white European origin provided by 19 (18) study groups that participate in the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA). A weighted cohort approach was used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI). Results: The minor allele of CASP8 D302H was significantly associated with a reduced risk of breast cancer (per-allele HR, 0.85; 95% CI, 0.76-0.97; Ptrend = 0.011) and ovarian cancer (per-allele HR, 0.69; 95% CI, 0.53-0.89; Ptrend = 0.004) for BRCA1 but not for BRCA2 mutation carriers. The CASP10 V410I polymorphism was not associated with breast or ovarian cancer risk for BRCA1 or BRCA2 mutation carriers. Conclusions: CASP8 D302H decreases breast and ovarian cancer risk for BRCA1 mutation carriers but not for BRCA2 mutation carriers. Impact: The combined application of these and other recently identified genetic risk modifiers could in the future allow better individual risk calculation and could aid in the individualized counseling and decision making with respect to preventive options in BRCA1 mutation carriers. Cancer Epidemiol Biomarkers Prev; 19(11); 2859–68. ©2010 AACR.

Haplotype analysis of the 185delAG BRCA1 mutation in ethnically diverse populations

The 185delAG* BRCA1 mutation is encountered primarily in Jewish Ashkenazi and Iraqi individuals, and sporadically in non-Jews. Previous studies estimated that this is a founder mutation in Jewish mutation carriers that arose before the dispersion of Jews in the Diaspora ∼2500 years ago. The aim of this study was to assess the haplotype in ethnically diverse 185delAG* BRCA1 mutation carriers, and to estimate the age at which the mutation arose. Ethnically diverse Jewish and non-Jewish 185delAG*BRCA1 mutation carriers and their relatives were genotyped using 15 microsatellite markers and three SNPs spanning 12.5 MB, encompassing the BRCA1 gene locus. Estimation of mutation age was based on a subset of 11 markers spanning a region of ∼5 MB, using a previously developed algorithm applying the maximum likelihood method. Overall, 188 participants (154 carriers and 34 noncarriers) from 115 families were included: Ashkenazi, Iraq, Kuchin-Indians, Syria, Turkey, Iran, Tunisia, Bulgaria, non-Jewish English, non-Jewish Malaysian, and Hispanics. Haplotype analysis indicated that the 185delAG mutation arose 750–1500 years ago. In Ashkenazim, it is a founder mutation that arose 61 generations ago, and with a small group of founder mutations was introduced into the Hispanic population (conversos) ∼650 years ago, and into the Iraqi–Jewish community ∼450 years ago. The 185delAG mutation in the non-Jewish populations in Malaysia and the UK arose at least twice independently. We conclude that the 185delAG* BRCA1 mutation resides on a common haplotype among Ashkenazi Jews, and arose about 61 generations ago and arose independently at least twice in non-Jews.

Involvement of IGF-1R regulation by miR-515-5p modifies breast cancer risk among BRCA1 carriers.

Several lines of evidence indicate that sequence alterations within microRNA (miRNA)-binding sites can modify the binding to its target gene resulting in altered expression patterns. We hypothesized that a single nucleotide polymorphism (SNP) located in the miR-515-5p binding site of igf-1r gene may alter IGF-1R regulation, with consequent effects on breast cancer risk in BRCA1 mutation carriers. Computational prediction revealed that the rs28674628 SNP in the igf-1r 3′ UTR is located within a predicted binding site for miR-515-5p. The effect of this SNP on breast cancer risk was evaluated by genotyping 115 Jewish Ashkenazi carriers of the 185delAG mutation in the BRCA1 gene using the Sequenom platform followed by Kaplan–Meier analysis. Additional data set of 378 Jewish BRCA1 carriers was analyzed to validate our results. MiRNA transfection, Western blot analysis, luciferase reporter assay, real time PCR, and immunohistochemistry were performed to assess direct regulation of igf-1r by miR-515-5p. We show direct regulation of IGF-1R by miR-515-5p. We identified that disrupting miR-515-5p and igf-1r 3′ UTR binding by SNP may cause elevated IGF-1R protein levels. Interestingly, miR-515-5p is downregulated in tumor tissue compared to its non-neoplastic surrounding tissue while IGF-1R levels are elevated. This igf-1r SNP was found to be significantly associated with age at diagnosis of breast cancer in Jewish Ashkenazi BRCA1 mutation carriers. These findings support the hypothesis that a SNP located in igf-1r gene may alter miRNA regulation of IGF-1R, with a putative effect on BRCA1 penetrance and breast cancer risk.

The rate of the predominant Jewish mutations in the BRCA1, BRCA2, MSH2 and MSH6 genes in unselected Jewish endometrial cancer patients

OBJECTIVES The genes associated with familial Endometrial Cancer (EC) are largely unknown. While EC is an integral part of Hereditary Non-Polyposis Colon Cancer, there is an ongoing debate if EC is indeed overrepresented in hereditary breast/ovarian cancer families. METHODS Unselected Jewish women with EC who were diagnosed from January 1982 to January 2008 were genotyped for the predominant mutations in Jewish individuals in BRCA1 (185delAG, 5382InsC, Tyr978X) BRCA2 (6174delT), MSH2 (A636P, 324delCA) and MSH6 (c.3984_3987dup). RESULTS Overall, 289 Jewish women with EC were included, the majority (217-75%) were Ashkenazim. Mean age at diagnosis was 62.6 ± 12 years, the most common histopathology was type I (endometrioid carcinoma) (80.4% of participants) with 29 having type II (Uterine papillary serous and clear cell cancer) Most patients (85.4%) had stage 1 disease by the FIGO staging. Five women (1.7%-2.3% of the Ashkenazim) carried either the BRCA1*185delAG (n = 4) or BRCA2*6174delT (n = 1) mutations, a rate similar with that of the general Ashkenazi population. Notably, none of 34 women with type II EC carried any BRCA1/BRCA2 mutations. Four (1.8%) and three (1.4%) of the 217 Ashkenazim patients harbored the c.3984_3987dup, A636P, MSH6 and MSH2 mutations, respectively, and 1/72 (1.4%) of the non-Ashkenazi patients harbored the 324delCA MSH2 mutation. Three of 42 (7.1%) women with EC diagnosed < 50 years carried either BRCA1 MSH6 or MSH2 mutations. CONCLUSIONS Our data do not support screening for BRCA1/2 mutations in consecutive EC patients.

MC1R variant alleles and malignant melanoma risk in Israel

To evaluate the contribution of MC1R variants to malignant melanoma risk in Israeli Jews, sequencing of the MC1R gene was performed in 132 melanoma patients and 184 ethnically matched controls. Overall, 22 MC1R variants were detected, two were novel (M73I and 496_497insG). Using age and sex-adjusted logistic regression, one specific variant, R151C, conferred significantly increased melanoma risk among Ashkenazim (OR=2.6, 95% CI: 1.3-5.3; p=0.05 after Bonferroni correction). A gene dosage effect was noted, with significantly increased melanoma risk being observed in subjects with at least two variants whether when all variants are pooled (OR=4.8, 95% CI: 2.0-11.2; p=0.002 after Bonferroni correction) or when red hair colour (RHC) variants and non-RHC variants are distinguished (OR=7.6, 95% CI: 2.8-20.3; p=0.0004 after Bonferroni correction). If further studies support these findings, the assessment of MC1R status may be useful in identifying Jewish Israeli individuals at high risk for melanoma.