Polymorphism in pre-miR-30c contributes to gastric cancer risk in a Chinese population

To explore the association between single nucleotide polymorphisms (SNPs) A/G in pre-miR-30c and gastric cancer risk and to assess various genotypes that affected the survival of patients, we performed a hospital-based, case-control study in Inner Mongolia autonomous region of China. A total of 240 gastric cancer patients and 240 age- and sex-matched cancer-free controls collected from 2006 to 2011 were enrolled in this study. Polymorphism rs928508 in pre-miR-30c was analyzed by TaqMan SNP genotyping assay. The expression of mature miR-30c was detected by real-time quantitative reverse transcription PCR in 48 gastric cancer specimens. Survival analysis was analyzed by the Kaplan-Meier survival curves. The genotype frequencies of pre-miR-30c A/G in gastric cancer patients were obviously different from those in the controls (P = 0.022). AA genotype carriers were associated with an increased risk of gastric cancer compared with GG genotype (adjusted odds ratio (OR) = 1.83, 95% confidence interval (CI): 1.07-3.15, P = 0.029). Moreover, the gastric cancer risk especially elevated in older individuals (aged >60 years), males, nonsmokers, and Helicobacter pylori (H. pylori)-infected individuals (adjusted OR = 2.66, 95% CI: 1.38-5.13, P = 0.004; adjusted OR = 1.90, 95% CI: 1.10-3.27, P = 0.022; adjusted OR = 1.94, 95% CI: 1.12-3.35, P = 0.018; adjusted OR = 1.83, 95% CI: 1.08-3.10, P = 0.024, respectively). Further stratified analysis indicated that AA genotype facilitated developing of gastric cancer with lymph node metastasis (adjusted OR = 2.23, 95% CI: 1.07-4.64, P = 0.032). Expression analysis detected that rs928508 AA showed a significantly increased level of mature miR-30c compared with GG or AG/GG genotype (P = 0.011 or P = 0.013). Patients with AA genotype were associated with unfavorable outcome in overall survival compared with AG/GG genotype (Log rank 5.848, P = 0.016). This study demonstrates that pre-miR-30c A/G polymorphism may be associated with an increased risk of gastric cancer in a Chinese population through altering mature miR-30c expression. However, their role as novel biomarkers for the diagnosis and prognosis of gastric diseases still needs to be systematically evaluated.