title: Enzymatic hypermethylation of DNA in mouse-mouse somatic cell hybrids.
abstract: Somatic cell hybrids between mouse L fibroblasts (A9 cells) and Ehrlich ascites tumour cells were constructed by use of poly(ethyleneglycol). The hybrids were selected in hypoxanthine/aminopterin/thymidine medium and morphologically different syncaryons were isolated by a micromanipulation. They were simultaneously analysed for their tumourogeneity, a release of certain proteins into the culture medium, the activity of pyrimidine salvage pathways, and the extent of enzymatic DNA methylation. None of these hybrids gave a rise of tumours if transplanted into DBA/2 mice. Two of the hybrids released a protein immunologically cross-reacting with antibody against C-peptide of human proinsulin. Activities of pyrimidine salvage pathways as measured by incorporation of [14C]deoxycytidine into DNA cytosine and thymine, respectively, are different in the analyzed cells. Enzymatic DNA methylation in somatic cell hybrids was significantly elevated as compared to the parental cell lines.
mesh_terms: D000818:Animals; D002096:C-Peptide / Q000276:immunology; D002286:Carcinoma, Ehrlich Tumor / Q000378:metabolism*; D004247:DNA / Q000378:metabolism*; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism; D006822:Hybrid Cells / Q000378:metabolism*; D007739:L Cells / Q000378:metabolism*; D051379:Mice; D009368:Neoplasm Transplantation; D011092:Polyethylene Glycols; D011863:Radioimmunoassay; D013972:Thyrotropin / Q000276:immunology
chemical_list: D002096:C-Peptide; D011092:Polyethylene Glycols; D013972:Thyrotropin; D004247:DNA; D004248:DNA (Cytosine-5-)-Methyltransferases