Ml. Gonzalgo et Pa. Jones, MUTAGENIC AND EPIGENETIC EFFECTS OF DNA METHYLATION, Mutation research-reviews in mutation research, 386(2), 1997, pp. 107-118
Tumorigenesis begins with the disregulated growth of an abnormal cell
that has acquired the ability to divide more rapidly than its normal c
ounterparts (Nowell, P.C. (1976) Science, 194, 23-28 [1]). Alterations
in global levels and regional changes in the patterns of DNA methylat
ion are among the earliest and most frequent events known to occur in
human cancers (Feinberg and Vogelstein (1983) Nature, 301, 89-92 ([2])
, Gama-Sosa, M.A. et al. (1983) Nucleic Acids Res., 11, 6883-6894 ([3]
); Jones, P.A. (1986) Cancer Res., 46, 461-466 [4]). These changes in
methylation may impair the proper expression and/or function of cell-c
ycle regulatory genes and thus confer a selective growth advantage to
affected cells. Developments in the field of cancer research over the
past few years have led to an increased understanding of the role DNA
methylation may play in tumorigenesis. Many of these studies have inve
stigated two major mechanisms by which DNA methylation may lead to abe
rrant cell cycle control: (1) through the generation of transition mut
ations via deamination-driven events resulting in the inactivation of
tumor suppressor genes, or (2) by altering levels of gene expression t
hrough epigenetic effects at CpG islands. The mechanisms by which the
normal function of growth regulatory genes may become affected by the
mutagenic and epigenetic properties of DNA methylation will be discuss
ed in the framework of recent discoveries in the field.