title: Decreased methylation rates of DNA in SV40-transformed human fibroblasts.
abstract: The rates of methylation of total cellular DNA and newly synthesized DNA were measured in four unrelated SV40-transformed human fibroblast lines and in four control parent fibroblast lines. Rates of methylation of total cellular DNA were decreased by a factor of 1.8-2.3 in the transformed cells relative to control cells. Methylation was largely (75%-87%) restricted to newly synthesized DNA in control and transformed fibroblasts, and methylation rates of newly synthesized DNA were diminished in transformed cells by 12- to 19-fold relative to control cells. Growth rates were similar in the normal and transformed cells. The cellular uptake of methionine and conversion to S-adenosylmethionine were similar in the normal and transformed cells, suggesting no major differences between the normal and transformed cells in the cellular transport of methionine, methionine S-adenosyltransferase activity, or the intracellular concentrations of methionine and S-adenosylmethionine. The diminished rates of DNA methylation that we have observed suggest a possible mechanism for altered gene expression and growth control in transformed cells.
mesh_terms: D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000378:metabolism*; D004273:DNA, Neoplasm / Q000032:analysis / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D008715:Methionine / Q000378:metabolism; D008745:Methylation; D012436:S-Adenosylmethionine / Q000378:metabolism; D013539:Simian virus 40
chemical_list: D004273:DNA, Neoplasm; D012436:S-Adenosylmethionine; D008715:Methionine