Functional polymorphism in the MicroRNA-367 binding site as a prognostic factor for colonic cancer

Background: As microRNAs play important roles in cancer development and progression by regulating the expressions of oncogenes and tumor suppressor genes though interacting with the 3' untranslated region (UTR) of target genes, we aimed to evaluate the association between genetic variants of miRNAs and their binding sites and prognosis in patients with colorectal cancer (CRC). Materials and Methods: Three miRNA variants and four variants in the miRNA binding sites were selected based on allelic frequencies, while their potential impact has been described in previous studies. DNA was extracted from fresh-frozen tissues of 344 patients with CRC who underwent curative surgery and genotyping analyses were performed using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. Results: Among seven target variants, rs1044129 at the miR-367 binding site of calcium channel ryanodine receptor gene 3 (RYR3) was associated with relapse-free survival (RFS) for colon cancer patients as a recessive model in a univariate analysis. Moreover, a multivariate analysis revealed that patients carrying the GG genotype had poor RFS, compared to those with the AA or AG genotype (hazard ratio, HR=2.864; p=0.005), yet there was only a marginal trend for disease-specific survival (HR=2.226; p=0.087) regardless of patient and tumor characteristics. Conclusion: The current study suggests that the functional variant (rs1044129) in the miR-367 binding site of RYR3 may be a potential marker for prognosis in patients following curative surgery for CRC.