Increased glutathione synthesis associated with platelet-derived growth factor stimulation of NIH3T3 fibroblasts

Previous data show a relation between GSH content and proliferation of norm al and tumour cells. We recently demonstrated a specific involvement of GSH in the autophosphorylation activity of the platelet-derived growth factor (PDGF) receptor in NIH3T3 fibroblasts. In this study we demonstrate that th e stimulation by PDGF of serum-starved NIH3T3 cells increases cellular GSH content, while no change in oxidized GSH content was measured. Experiments performed with actinomycin, cycloheximide and buthionine sulfoximide, a spe cific inhibitor of the rate-limiting enzyme of the de novo synthesis of GSH gamma-glutamylcysteine synthetase (gamma-GCS), confirm PDGF induction of G SH synthesis. These results provide the first demonstration that PDGF media ted transduction signals seem strictly related to mechanisms involved in:th e increase of gamma-GCS activity associated with increased gamma-GCS heavy subunit mRNA levels. In fact, serum and epidermal growth factor (EGF) stimu lation of quiescent NIH3T3 and NIH3T3, which overexpress EGF receptor, does not affect GSH content or its synthesis. These data may be related to a po ssible GSH role in the redox regulation of cell proliferation mediated by P DGF. (C) 1999 Elsevier Science B.V. All rights reserved.