A Genetic Variant in miR-196a2 Increased Digestive System Cancer Risks: A Meta-Analysis of 15 Case-Control Studies

Background: MicroRNAs (miRNAs) negatively regulate the gene expression and act as tumor suppressors or oncogenes in oncogenesis. The association between single nucleotide polymorphism (SNP) in miR-196a2 rs11614913 and the susceptibility of digestive system cancers was inconsistent in previous studies. Methodology/Principal Findings: An updated meta-analysis based on 15 independent case-control studies consisting of 4999 cancer patients and 7606 controls was performed to address this association. It was found that miR-196a2 polymorphism significantly elevated the risks of digestive system cancers (CT vs. TT, OR=1.25, 95% CI=1.07-1.45; CC vs. TT, OR=1.38, 95% CI=1.13-1.67; CC/CT vs. TT, OR=1.29, 95% CI=1.10-1.50; CC vs. CT/TT, OR=1.14, 95% CI=1.01-1.30; C vs. T, OR=1.15, 95% CI=1.05-1.26). We also found that variant in miR-196a2 increased the susceptibility of colorectal cancer (CRC) (CT vs. TT, OR=1.23, 95% CI=1.04-1.44; CC vs. TT, OR=1.32, 95% CI=1.08-1.61; CC/CT vs. TT, OR=1.25, 95% CI=1.07-1.46; C vs. T, OR=1.15, 95% CI=1.05-1.28), while the association in recessive model (CC vs. CT/TT, OR=1.16, 95% CI=0.98-1.38) showed a marginal significance. Additionally, significant association between miR-196a2 polymorphism and increased risk of hepatocellular cancer (HCC) was detected. By stratifying tumors on the basis of site of origin, source of controls, ethnicity and allele frequency in controls, elevated cancer risks were observed. Conclusion/Significance: Our findings suggest the significant association between miR-196a2 polymorphism and increased susceptibility of digestive system cancers, especially of CRC, HCC and Asians. Besides, C allele may contribute to increased digestive cancer risks.