Promoter methylation status of hMLH1, MGMT, and CDKN2A/p16 in colorectal adenomas.

Aim: To investigate aberrant DNA methylation of CpG islands and subsequent low- or high-level DNA microsatellite instability (MSI) which is assumed to drive colon carcinogenesis.

Methods: DNA of healthy individuals, adenoma (tubular or villous/tubulovillous) patients, and colorectal carcinoma patients who underwent colonoscopy was used for assessing the prevalence of aberrant DNA methylation of human DNA mismatch repair gene mutator L homologue 1 (hMLH1), Cyclin-dependent kinase inhibitor 2A (CDKN2A/p16), and O-6-methylguanine DNA methyltransferase (MGMT), as well as their relation to MSI.

Results: The frequency of promoter methylation for each locus increased in the sequence healthy tissue/adenoma/carcinoma.