rs15869 at miRNA binding site in BRCA2 is associated with breast cancer susceptibility

BRCA1 and BRCA2 mutations confer an increased lifetime risk of breast cancer; however, the associations of microRNA (miRNA) binding site single nucleotide polymorphisms (SNPs) in 3′ untranslated region (3′-UTR) of BRCA1 and BRCA2 with breast cancer (BC) risk were rarely reported. In this case–control study (498 BC patients and 498 matched controls), three SNPs (rs8176318, rs12516 and rs15869) were selected in the 3′-UTR of BRCA1 and BRCA2 genes, which were within miRNA-binding seed regions and might have potential function to regulate the expression of BRCA1/BRCA2. Unconditional logistic regression model was used to analyze the association between three SNPs and BC risk with adjustment of reproductive factors, and Student’s t test was performed to assess relative expression of BRCA2 in human breast cancer cell lines. Multifactor dimensionality reduction method was applied to calculate gene–reproductive factors interactions. A novel finding showed that AC [odds ratio (OR) 1.524; 95% confidence interval (CI) 1.141–2.035] genotype of rs15869 in BRCA2 could increase the risk of BC and recombinant plasmid-pGenesil-1-miR-627 could negatively regulate the expression of BRCA2 in MCF-7 and MDA-MB-231 cells. Gene–reproductive factors interactions analysis revealed that rs15869 together with age at menarche and number of pregnancy could increase the risk of BC by 2.39-fold and TT genotype (OR 0.316; 95% CI 0.130–0.767) of rs8176318 had a significant association with progesterone receptor status in BC patients. Our findings suggest that the miRNA-binding SNPs in BRCA1/BRCA2 and their interaction with reproductive factors might contribute to BC risk, and miR-627 might down-regulate BRCA2 expression in MCF-7 and MDA-MB-231 cells.