A Functional Variant at miR-520a Binding Site in PIK3CA Alters Susceptibility to Colorectal Cancer in a Chinese Han Population

An increasing body of evidence has indicated that polymorphisms in the miRNA binding site of target gene can alter the ability of miRNAs to bind their target genes and modulate the risk of cancer. We aimed to investigate the association between a miR-520a binding site polymorphism rs141178472 in the PIK3CA 3'-UTR and the risk of colorectal cancer (CRC) in a Chinese Han population. The polymorphism rs141178472 was analyzed in a case-control study, including 386 CRC patients and 394 age- and sex-matched controls; the relationship between the polymorphism and the risk of colorectal cancer was examined. Individuals carrying the rs141178472 CC genotype or C allele had an increased risk of developing CRC (CC versus TT, OR (95% CI): 1.716 (1.084-2.716), P = 0.022; C versus T, OR (95% CI): 1.258 (1.021-1.551), P = 0.033). Furthermore, the expression of PIK3CA was detected in the peripheral blood mononucleated cell of CRC patients, suggesting that mRNA levels of PIK3CA might be associated with SNP rs141178472. These findings provide evidence that a miR-520a binding site polymorphism rs141178472 in the PIK3CA 3'-UTR may play a role in the etiology of CRC.