Evaluation of CpG-SNPs in miRNA promoters and risk of breast cancer

CpG-SNPs in gene promoter regions are proposed to be associated with multiple diseases. To date, few studies have focused on the associations between CpG-SNPs in miRNA promoters and the risk of breast cancer. In this study, 138 miRNAs differentially expressed between breast cancer and non-cancer tissues (fold change > 2, P < 0.05) were identified using The Cancer Genome Atlas (TCGA) Research database. In total, 13 SNPs were selected in the promoters of the miRNAs and were evaluated in a case-control study of Chinese women including 1486 cases and 1519 controls. After multivariate logistic regression analysis, we found that three CpG-SNPs: rs1190983, rs155247, and rs62382272, were significantly associated with breast-cancer susceptibility in the population (Additive model: rs1190983: adjusted OR = 0.88, 95% CI: 0.79-0.99, P = 0.034; rs155247: adjusted OR = 0.83, 95% CI: 0.74-0.93, P = 0.002; rs62382272: adjusted OR = 1.24, 95% CI: 1.04-1.47, P = 0.016). eQTL analysis showed that these three SNPs were correlated with the expression of the related miRNAs in TCGA breast cancer tissues (P = 0.006,0.009,0.001 for rs1190983, rs155247, and rs62382272). Furthermore, rs1190983 was found to be associated with CpG site (cg20488673) methylation (meQTL) (P = 0.004), which was in turn correlated with miR-342 expression (P = 0.016). These findings indicated that the three CpG-SNPs in the promoters of miRNAs were likely to possess important biological functions to breast cancer in the Han Chinese population.