title: DNA methylation in breast and colorectal cancers.
abstract: DNA methylation is one of several epigenetic changes observed in cells. Aberrant methylation of tumor suppressor genes, proto-oncogenes, and vital cell cycle genes has led many scientists to investigate the underlying cellular mechanisms of DNA methylation under normal and pathological conditions. Although DNA methylation is necessary for normal mammalian embryogenesis, both hypo- and hypermethylation of DNA are frequently observed in carcinogenesis and other pathological disorders. DNA hypermethylation silences the transcription of many tumor suppressor genes, resulting in immortalization of tumor cells. The reverse process, demethylation and restoration of normal functional expression of genes, is augmented by DNA methylation inhibitors. Recent studies suggest that DNA hypomethylation may also control gene expression and chromosomal stability. However, the roles of and relationship between hypomethylation and hypermethylation are not well understood. This review provides a brief overview of the mechanism of DNA methylation, its relationship to extrinsic stimulation including dietary intake and aging, and of abnormally methylated DNA in breast and colorectal cancers, which could be used as prognostic and diagnostic markers.
authors.affiliation: Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE 68178, USA.
authors.forename: Anshu
authors.initials: A
authors.lastname: Agrawal
authors.forename: Richard F
authors.initials: RF
authors.lastname: Murphy
authors.forename: Devendra K
authors.initials: DK
authors.lastname: Agrawal
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019175:DNA Methylation; D006801:Humans; D007211:Indoles / Q000494:pharmacology / Q000627:therapeutic use; D008297:Male; D010797:Phthalimides / Q000494:pharmacology / Q000627:therapeutic use; D011725:Pyridines / Q000494:pharmacology / Q000627:therapeutic use; D014230:Triazoles / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D007211:Indoles; C508801:NSC 303530; C508802:NSC 401077; D010797:Phthalimides; D011725:Pyridines; D014230:Triazoles; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases