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Evaluation of the Transformation Assay Using C3H 10T1/2 Cells for Use in Screening Chemicals for Carcinogenic Potential.

NIOSH 1980 May:298-305
An in-vitro transformation assay for screening the carcinogenic potential of chemicals was evaluated. C3H 10T 1/2 cells were cultured that had a plating efficiency of 23 percent, a saturation density of 590,000, and a generation time of about 16 hours. The assay was evaluated with and without an exogenous metabolic activation system using known chemical carcinogens by scoring for Type III foci and by determining the ability of cells from Type III foci to grow in soft agar and produce tumors when injected into irradiated C3H mice. Benzo(a)pyrene (50328) (BaP), 3- methylcholanthrene (56495) (3-MC), dibenz(a,h)anthracene (53703), and 7,12-dimethylbenz(a)anthracene (57976) gave positive responses without metabolic activation, but transformation frequency and dose at which a positive response occurred varied. Anthracene (120127), phenanthrene (85018), 2-acetylaminofluorene (53963) (2-AAF), and N- methyl-N-nitro-N-nitrosoguanidine (70257) (MNNG) were not active in the absence of metabolic activation. BaP was active in the presence of an S-9 activation system, but 3-MC and diethylnitrosamine (55185) (DEN) were not. An amplification modification caused MNNG to be active but did not increase the transformation caused by 3-MC over that occuring in the standard assay. The author concludes that the assay warrants further development to identify factors influencing the assay and determine procedures leading to standardization.
Bioassays; Screening-methods; Biochemical-tests; In-vitro-study; Carcinogens; Carcinogenesis; Biotransformation; Medical-screening;
50-32-8; 56-49-5; 53-70-3; 57-97-6; 120-12-7; 85-01-8; 53-96-3; 70-25-7; 55-18-5;
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Proceedings of the First NCI/EPA/NIOSH Collaborative Workshop: Progress on Joint Environmental and Occupational Cancer Studies, May 6-8, 1980, Rockville, Maryland, H. F. Kraybill, I. C. Blackwood, and N. B. Freas, Eds. National Cancer Institute, Environmental Protection Agency, National Institute for Occupational Safety and Health