An in-vitro study of known carcinogens was conducted. Compounds were evaluated for their ability to inhibit metabolic cooperation in an assay system consisting of wild type and mutant (HGPRT-) Chinese-V- 79-hamster cells. Mezerein (34807415), and 12-O- tetradecanoylphorbol-13-acetate (544638) strongly inhibited metabolic cooperation. Sodium-saccharin (128449), sodium- phenobarbital (57307), phorbol (17673255), butylated-hydroxytoluene (128370), butylated-hydroxyanisole (25013165), tert-butyl- hydroperoxide (75912), hydrogen-peroxide (7722841), benzoyl-peroxide (94360), and 2,4-dinitrofluorobenzene (70348) did not inhibit metabolic cooperation. Sodium-cyclamate (139059), tryptophan (153946), and amobarbital (57432) showed ambiguous or weakly positive results. The authors conclude that from comparison of results with those of in-vivo cancer bioassays, the Chinese-V-79- hamster cell assay system correctly identifies tumor promoting ability. The system is most effective in detecting known skin cancer promoters; however, the rate of false negative results is high (50 percent). Further research is recommended to improve the assay system so it can detect weak and non skin tumor promoters and to reduce the number of false negative responses.
Division of Biomedical and Behavioral Sciences, NIOSH, U.S. Department of Health and Human Services, Cincinnati, Ohio