thioguanine-anhydrous and Cocarcinogenesis

Inhibition of intercellular communication, as measured by metabolic cooperation between 6-thioguanine-sensitive and resistant Chinese hamster V79 cells, has been previously shown to be correlated with a large variety of known tumor promoters in many species and organ systems. The effects of anthralin and oleic acid, at non-cytotoxic concentrations, were shown to eliminate metabolic cooperation in Chinese hamster cells. Moreover, increased serum levels appear to reduce the effectiveness of 12-O-tetradecanoylphorbol-13-acetate, a powerful tumor promoter and inhibitor of metabolic cooperation, to eliminate metabolic cooperation. Results are consistent with the hypothesis that inhibition of metabolic cooperation is associated with an aspect of the complex tumor promotion process and indicate that in vitro culture conditions are critical for the proper assessment of potential tumor promoters.

Topics: Animals; Anthracenes; Anthralin; Cell Communication; Cells, Cultured; Cocarcinogenesis; Cricetinae; Drug Resistance; Oleic Acids; Tetradecanoylphorbol Acetate; Thioguanine

Using an in vitro assay system, polybrominated biphenyl (PBB) was assessed for its ability to inhibit metabolic cooperation between 6-thioguanine sensitive and resistant Chinese hamster V79 cells. Using a nonlethal range of the chemical, PBB was shown to inhibit metabolic cooperation (a form of cell-cell communication) in a manner similar to other known tumor promoters. Results suggest that PBB could act, epigenetically, as a teratogen and a carcinogenic promoter.

Topics: Animals; Biphenyl Compounds; Carcinogens; Cell Communication; Cell Line; Cocarcinogenesis; Cricetinae; Cricetulus; Dose-Response Relationship, Drug; Drug Resistance; Fibroblasts; Intercellular Junctions; Lung; Polybrominated Biphenyls; Thioguanine