N-nitrosodiethylamine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone induced morphological transformation of C3H/10T1/2CL8 cells expressing human cytochrome P450 2A6.
Transfection of specific genes into cells capable of expressing chemically induced morphological cell transformation provides a valuable approach to study the mechanisms of action of carcinogens. A human cytochrome P450 isozyme, CYP2A6, has been successfully expressed from a retroviral vector in transformable C3H/10T1/2 (10T1/2) mouse embryo fibroblasts and these resulting 10T1/2 clones were evaluated for the cytotoxic and transforming activities of two nitrosamines, 4-(methylnitrosamine)-1-(3-pyridyl)-1-butanone (NNK) and N-nitrosodiethylamine (DEN). 10T1/2 clone 29 cells, which expressed high levels of CYP2A6 activity, were responsive to the cytotoxic and morphological transforming effects of DEN or NNK on a concentration-related basis. In 10T1/2 clone 29 cells, DEN at 600 micrograms/ml decreased cell survival to 67%, and induced 0.5 type II&III foci/dish. NNK at 400 micrograms/ml administered to 10T1/2 clone 29 cells decreased survival to 57% and induced 0.43 type II&III foci/dish. Wild-type 10T1/2 cells and 10T1/2 clone 4 cells (infected with the vector but not expressing the CYP2A6 activity) were unresponsive. These results indicate that expression of a cDNA coding for cytochrome P450 in 10T1/2 cells can provide information about the role of the enzyme in the activities of chemical carcinogens and also increase the sensitivity of 10T1/2 cells to a larger number of classes of chemical carcinogens.
Carcinogenesis and Metabolism Branch, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711.
S
S
Nesnow
S
S
Beck
S
S
Rosenblum
J
J
Lasley
H F
HF
Tiano
M
M
Hosokawa
C L
CL
Crespi
R
R
Langenbach
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D001711:Biotransformation; D002274:Carcinogens, Environmental / Q000378:metabolism / Q000633:toxicity*; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced* / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D002999:Clone Cells; D065637:Cytochrome P-450 CYP2A6; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D004052:Diethylnitrosamine / Q000378:metabolism / Q000633:toxicity*; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology; D051379:Mice; D008809:Mice, Inbred C3H; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D009602:Nitrosamines / Q000378:metabolism / Q000633:toxicity*; D014162:Transfection
D002274:Carcinogens, Environmental; D009602:Nitrosamines; D004052:Diethylnitrosamine; C016583:4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C585710:CYP2A6 protein, human; D065637:Cytochrome P-450 CYP2A6