Quantitative validation of GJC1 promoter hypermethylation in benign and malignant colorectal tumors.

We have previously shown that the gap junction protein gamma 1 (GJC1) gene, encoding the connexin-45 protein, is inactivated by promoter hypermethylation in colorectal cancer. This was confirmed in a recent Endocrine-Related Cancer publication analyzing a limited number of samples. The aim of this study was to analyze GJC1 in a larger clinical cohort (n=485) and to assess whether or not the promoter hypermethylation was associated with clinical or pathological features. The methylation of GJC1 was confirmed to be tumor specific and was observed in 33% of colorectal cancers and 12% of adenomas. The methylation was strongly associated with BRAF mutations (P=5.64x10(-13)) as well as with proximal tumor location (P=1.42x10(-3)), features compatible with a CpG island methylator phenotype. Endocrine-Related Cancer (2011) 18 C31-C34