Glutathione in human melanoma cells. Effects of cysteine, cysteine esters and glutathione isopropyl ester

Thiols are of great importance for the regulation of many cellular functions including metabolism, transport and cell protection. In this study the usefulness of L-cysteine methyl and octyl esters, of N,S-diacetyl-L-cysteine methyl ester and glutathione isopropyl ester as cellular cysteine and GSH delivery systems was investigated in the human IGR 1 melanoma cell line. The L-cysteine methyl and octyl esters proved to be highly toxic to the cells. Treatment of the cultures with 1 mM N,S-diacetyl-L-cysteine methyl ester or 3 mM glutathione isopropyl ester for 24 h resulted in marked elevation of the cellular glutathione level without apparent or with slight cell loss, respectively. Thus the administration of the latter two compounds seems to be suitable for inducing GSH elevation in the cultured melanoma cells.