Associations of miRNA polymorphisms and expression levels with breast cancer risk in the Chinese population

Single-nucleotide polymorphisms in microRNAs (miRNAs) may dramatically affect gene expression and subsequently alter individual susceptibility to cancer, and thus has become a research hotspot for many cancer types, including breast cancer. We recruited 321 breast cancer patients and 290 controls in our study. Four established miRNA single-nucleotide polymorphisms (mir-499 rs3746444 A>G; miR-27a rs895819 A>G; miR-196a2 rs11614913 T>C; miR-146a rs2910164 G/C) were detected using Taqman assays. Mature miRNA expression, allele distribution, and the association with clinical features were further analyzed. Our results showed that the miR146a rs2910164 G/C polymorphism was associated with an elevated risk of breast cancer (odds ratio = 1.85, 95% confidence interval = 1.03-3.32; P < 0.05). Compared with the ancestral T allele in miR-196a2 rs11614913, the variant C allele was consistently associated with an increased risk of breast cancer (odds ratio = 2.20, 95% confidence interval = 1.19-4.09, P < 0.01) and clinical pathological type (P < 0.01). miR-27a rs895819 A>G and miR-499 rs3746444 A>G were not associated with breast cancer risk. Analysis of mature miRNA expression confirmed that the variant C allele in miR146a rs2910164 and miR-196a2 rs11614913 dramatically inhibited production of their mature products. Our results suggested that miR-146a rs2910164 G>C and miR-196a2 rs11614913 T>C may be biomarkers for predicting breast cancer risk in the Chinese population.