DNA methylation of CMTM3, SSTR2, and MDFI genes in colorectal cancer

Colorectal cancer (CRC) is increasingly common worldwide, including in China. Therefore, there is an increasing need to detect CRC at an early stage and to discover and evaluate diagnostic and prognostic biomarkers. DNA methylation of genes in CRC is a potential epigenetic biomarker for the early detection of CRC. This study was performed to analyze the methylation frequency of six candidate genes, CMTM3, SSTR2, MDFI, NDRG4, TGFB2, and BCL2L11, in fresh-frozen CRC tissues and adjacent normal colorectal tissues, from 42 patients with CRC. DNA isolation, bisulphite modification, and pyrosequencing were performed. The sensitivity, specificity, and the area under the receiver operator characteristic (ROC) curve (AUC) were evaluated to determine whether these genes showed any associations with tumor grade, stage, or diagnostic features. Among the tested genes, three genes, CMTM3, SSTR2, and MDFI were significantly methylated in CRC tissues when compared with adjacent normal colorectal tissues. The ROC analysis showed that a multigene model, including CMTM3, SSTR2, and MDFI, had a sensitivity of 81% and a specificity of 91% with an AUC value of 0.92. The findings of this study have shown that DNA methylation of the genes, CMTM3, SSTR2, and MDFI should be studied further with a view to determining their potential role as biomarkers for CRC.