rs712 polymorphism within let-7 microRNA-binding site might be involved in the initiation and progression of colorectal cancer in Chinese population

rs712 within 3'-untranslated region of KRAS can affect the specific binding between the mRNA and its targeted microRNAs, leading to the activation of KRAS oncogene. However, the possible association between the locus and susceptibility to colorectal cancer (CRC) remains unclear. We investigated genotypes of the locus in 586 cases and 476 controls to explore the possible association between them. Results of our case-control study showed that genotypes TT (6.5% vs 2.5%, P=0.002, adjusted odds ratio [OR] =2.810, 95% confidence interval [CI] = 1.342-5.488) and GT/TT (36.5% vs 30.5%, P=0.038, adjusted OR =1.342, 95% CI = 1.030-1.712) and allele T (21.5% vs 6.5%, P=0.004, adjusted OR = 1.328, 95% CI = 1.105-1.722) of rs712 were significantly associated with an increased risk of CRC, and the significant association was also observed in the recessive model (TT vs GG/GT, 6.5% vs 2.5%, P=0.003, adjusted OR = 0.372, 95% CI = 0.191-0.725). However, there was no association between genotype GT and risk of CRC (30.0% vs 28.0%, P=0.235, adjusted OR = 1.210, 95% CI = 0.903-1.548). Furthermore, genotype GT (P= 0.003) and allele T (P= 0.003) were significantly associated with poor differentiation, and genotypes GT and TT and allele T were significantly associated with tumor-node-metastases stage III (P=0.001 for GT vs GG, P<0.001 for TT vs GG, and P<0.001 for T vs G) and node metastasis (P<0.001 for GT vs GG, P=0.001 for TT vs GG, and P<0.001 for T vs G), respectively. These findings indicated that allele T and genotypes TT and GT/TT of rs712 might be susceptible factors for CRC, and mutated allele and genotypes of the locus might predict a poor clinical outcome in Chinese population.