title: Effects of diverse intracellular thiol delivery agents on glutathione peroxidase activity, the ratio of reduced/oxidized glutathione, and ornithine decarboxylase induction in isolated mouse epidermal cells treated with 12-O-tetradecanoylphorbol-13-acetate.
abstract: Since the enhancement of the activity of the natural glutathione (GSH)-dependent antioxidant protective system of the epidermal cells appears to inhibit the oxidative challenge presumably linked to skin tumor promotion by 12-O-tetradecanoylphorbol-13-acetate (TPA), we have compared the effectiveness of diverse intracellular thiol delivery agents as inhibitors of the effects of TPA on GSH metabolism and ornithine decarboxylase (ODC; L-ornithine carboxylase, EC 4.1.1.17) induction in isolated mouse epidermal cells. Here we report at a 2-mM concentration, the monoethyl and monomethyl esters of GSH, N-acetyl-L-cysteine, and L-2-oxothiazolidine-4-carboxylate are all significantly more effective than GSH in inhibiting the sharp decline in the intracellular ratio of reduced GSH/oxidized glutathione (GSSG), the prolonged decrease in GSH peroxidase (GSH:H2O2 oxidoreductase, EC 1.11.1.9) activity, and the induction of ODC activity caused by 1 microM TPA. Moreover, diethyldithiocarbamate prevents totally the initial drop in the GSH/GSSG ratio of TPA-treated cells and is the most potent inhibitor of TPA-decreased GSH peroxidase activity in relation with its remarkable 98% inhibition of TPA-induced ODC activity, suggesting that the potential antitumor-promoting activity of this compound in mouse skin may be far superior to that previously demonstrated by GSH in the initiation-promotion protocol.
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D004050:Ditiocarb / Q000494:pharmacology; D004817:Epidermis / Q000187:drug effects / Q000201:enzymology*; D005260:Female; D005978:Glutathione / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D005979:Glutathione Peroxidase / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D009955:Ornithine Decarboxylase / Q000378:metabolism*; D010084:Oxidation-Reduction; D011761:Pyrrolidonecarboxylic Acid; D013438:Sulfhydryl Compounds / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines
chemical_list: D013438:Sulfhydryl Compounds; D013844:Thiazoles; D053778:Thiazolidines; C042431:S-ethyl glutathione; D004050:Ditiocarb; D005979:Glutathione Peroxidase; D009955:Ornithine Decarboxylase; D005978:Glutathione; D013755:Tetradecanoylphorbol Acetate; C017514:S-methyl glutathione; D011761:Pyrrolidonecarboxylic Acid; D000111:Acetylcysteine; C029536:2-oxothiazolidine-4-carboxylic acid