A functional variant of IC53 correlates with the late onset of colorectal cancer.

The IC53 gene was reported to be upregulated in the colon adenocarcinoma cell line SW480. Here, we show that the expression level of IC53 is positively correlated with the grade and depth of invasion in adenocarcinoma of the colon. Injection of IC53 stably transfected HCT-116 cells into athymic nude mice promoted tumor growth. Furthermore, overexpression of IC53 increased cell invasive growth, which could be dramatically prevented by knocking down IC53 with siRNA. The effects of IC53 on cell-invasive growth were mediated by upregulation of integrins, activation of phosphatidylinositol 3-kinase and phosphorylation of Akt. A single-nucleotide polymorphism rs2737 in the IC53 gene created a potential microRNA379 target site, and microRNA379 expression inhibited IC53 translation. Among 222 patients with colorectal cancer, the C/C rs2737 genotype was associated with late onset of colorectal cancer (median age 63.0 versus 55.3 years, P = 0.003). The frequency of the C/C rs2737 genotype was much lower in patients who developed colorectal cancer below the age of 45 years than in individuals over age 45 years (10.8% versus 26.6%, P = 0.039). These data indicated that IC53 is a positive mediator for colon cancer progression, and IC53-rs2737 may serve as protection from the onset of colorectal cancer.