Association between a functional variant in microRNA-27a and susceptibility to colorectal cancer in a Chinese Han population.

Polymorphisms in pri-, pre-, and mature-microRNAs (miRNAs) have been proposed to be associated with various human cancers. Common single nucleotide polymorphisms (SNPs) in miRNA genes can influence the maturation of miRNAs or miRNA-mediated transcriptional regulation. Through genotyping the rs895819 SNP in 254 colorectal cancer (CRC) patients and 238 healthy controls by polymerase chain reaction-restricted fragment length polymorphism, a case-control study was performed to investigate a possible association between a common A/G polymorphism (rs895819) within hsa-mir-27a and susceptibility to CRC in a Chinese Han population. In addition, after examining miR-27a expression levels in CRC tissues (N=57) obtained from these CRC patients, we found that subjects with variant genotypes (AG+GG) had a significantly increased risk of developing CRC compared to AA carriers (odds ratio (OR)=1.619, 95% confidence interval (CI)=1.129-2.322). The elevated risk was especially evident in older (age≥60 years) and male subjects. Further functional analyses indicated that the relative expression of miR-27a was significantly greater in tumor tissues from GG patients or patients carrying at least one G allele than in those from AA patients. In conclusion, we provide the first evidence that an miR-27a polymorphism contributes to CRC susceptibility in the Chinese Han population by modulating mature miR-27a expression.