Stems cells of the colon crypt are the origin of colon mature cells. Colorectal cancer cells are also suggested to originate from crypt stem cells undergoing a series of epigenetic and genetic alterations. Aberrant methylation plays important roles in early carcinogenesis and lead to altered gene expression and regulation, resulting in accumulation of damages to cell function and ultimately, malignant transformation. Aberrances in hypermethylation and hypomethylation act in different mechanism through the regulation of various genes during CSC carcinogenesis, and both of them play crucial roles in stem cell differentiation towards cancer cells. A large majority of epigenetic and genetic abnormalities that work coordinately in colorectal carcinogenesis are related to cell growth and division, indicating that the intrinsic abnormalities of CRC lie in dysregulation of basic cellular processes. Detection of abnormal methylation can be used in cancer screening and early detection, while reversal of aberrant methylation using drugs may have potential in cancer therapy. This review will provide an overview on the roles of aberrant methylation and a summary of genes that are affected during CRC carcinogenesis.
Keywords: Adenoma; Cancer stem cell; Colorectal cancer; Hypermethylation; Hypomethylation; Methylation; SEPT9; Stem cell.