Three common functional polymorphisms in microRNA encoding genes in the susceptibility to hepatocellular carcinoma: a systematic review and meta-analysis

Emerging evidences have shown that common genetic polymorphisms in microRNAs may be associated with the development of hepatocellular carcinoma (HCC); but individually published studies and previous meta-analyses revealed inconclusive results. The aims of this review and meta-analysis are to assess whether common single-nucleotide polymorphisms (SNPs) in the genes encoding the microRNAs are associated with susceptibility to HCC development and clinicopathologic characteristics of hepatitis B virus (HBV) related HCC. A computerized search was performed in PubMed, Embase, Web of Science and China BioMedicine (CBM) databases to identify relevant articles published before January 1st 2013. Ten case-control studies were assessed with a total of 3437 cases and 3437 healthy controls. Three common functional SNPs in miRNA-encoding genes were found, including miR-146a G>C (rs2910164), miR-196a-2 C>T (rs11614913) and miR-499 T>C (rs3746444). This meta-analysis revealed that the miR-146a C variant was associated with a decrease in HCC risk, especially among Asian and male populations; while the miR-196a-2 T variant was associated with susceptibility to HCC among Caucasian populations. However, we failed to find any significant correlations between the miR-499 C polymorphism and HCC risks. When further stratification on HBV status was conducted, a similar trend of association between the three SNPs and the HBV-related HCC risks was observed, but these results were not statistically significant due to small sample sizes. The current meta-analysis demonstrates that SNPs contained in the genes encoding miR-146a and miR-196a-2 may play a major role in genetic susceptibility to HCC.