Elimination of metabolic cooperation by glycyrrhetinic acid, an anti-tumor promoter, in cultured Chinese hamster cells.

The effect of glycyrrhetinic acid (GA) on the metabolic cooperation between 6-thioguanine-resistant (6TGR) and sensitive (6TGS) Chinese hamster V79 H3 cells, was investigated. Because GA has been reported to inhibit strongly tumor formation in mouse skin induced by 7,12-dimethylbenz[a]anthracene (DMBA) plus teleocidin or DMBA plus 12-O-tetradecanoylphorbol-13-acetate (TPA), we expected that GA might restore the metabolic cooperation inhibited by TPA. The results were contrary to our expectations. GA (20-50 microM) acted cumulatively with TPA to inhibit metabolic cooperation even more, and GA (20-75 microM), by itself, was found to be a strong inhibitor of metabolic cooperation. GA was not mutagenic at the concentrations examined (0-100 microM).