Growth inhibition and prostaglandin metabolism in the R3230AC mammary adenocarcinoma by reduced glutathione.

The effect of reduced glutathione (GSH) administered to tumor-bearing rats was studied on growth of the R3230AC mammary adenocarcinoma. A significant inhibition in both tumor weight and volume was observed in rats given 2 g/kg body weight/day of GSH. Prostaglandin content of processed tumors was measured (ng/g wet weight tissue) and in vitro prostaglandin synthesis by microsomal prostaglandin synthetase was studied (ng/mg protein/15 min). Tumor PGE2 content and in vitro synthesis were decreased in tumors from GSH-treated rats. However, PGE1, PGF2 alpha, 6-keto-PG-F1 alpha and TXB2 content of these tumors was increased, and with the exception of PGE1, the trends in tumor content and in vitro enzyme activity were similar. The effect of GSH treatment on PGE2 content of normal mammary tissue was similar to that observed in the mammary tumors. These studies suggest that a selective inhibition in tumor PGE2 by in vivo treatment of rats with GSH may be associated with GSH-induced tumor growth inhibition.