Aberrant methylation detection of the hMLH1 promoter and the IGF2 DMR region using methylation-sensitive high resolution melting (MS-HRM) in colorectal cancer

Abstract

Epigenetic alterations and gene mutations causing inactivation of tumor suppressor genes and activation of oncogenes can regulate signaling pathways contributing to colon cancer formation. Many genes have been reported to be aberrantly methylated in the CRC genome, and it is likely that only subsets of these genes are important in the pathogenesis of colorectal tumors. We applied the methylation-specific high resolution melting (MS-HRM) technique to study methylation of the IGF2 DMR and the hMLH1 gene promoter in 60 colorectal cancer and adjacent normal tissues of same patients compare to 20 normal tissue samples. In this study, 5 of the 60 colorectal cancer samples (8.3%) were found to be methylated at the hMLH1 promoter region and 32 of the 60 colorectal cancer samples (53.3%) were found to be hypomethylated at the IGF2 DMR region. Adjacent normal tissues were unmethylated for hMLH1 and 5% showed hypomethylation for IGF2 DMR. There was significant correlation between aberrant methylation of hMLH1 and IGF2 DMR with tumor location (p=0.002, p=0.026 respectively). In addition, a tendency of association between IGF2 DMR hypomethylation and age (p=0.06) was observed. We demonstrated effectiveness of the MS-HRM technique to analyze methylation of IGF2 DMR and hMLH1 promoter region and methylation significantly correlated with tumor location in colorectal cancer patients.