Inhibitory effects of S-nitrosoglutathione on cell proliferation and DNA synthesis:: possible role of glyoxalase I inactivation

We investigated the inhibitory effects of S-nitrosoglutathione (GSNO) on cell proliferation, DNA synthesis and several enzymatic activities using spontaneously immortalized human endothelial cells (ECV304). Proliferation of ECV304 was inhibited by GSNO in a dose-dependent manner (125-1000 muM). DNA synthesis was decreased 2 h after addition of GSNO to cells and was markedly repressed from 20 h after the addition. The activity of ribonucleotide reductase, a rate-limiting enzyme for DNA synthesis, was unchanged in GSNO-treated cells. GSNO inhibited less than 40%, of mitochondrial respiration activity, and the membrane potential and cellular levels of ATP were not significantly decreased by GSNO. GSNO had no inhibitory effect on activities of glutathione peroxidase, glutathione S-transferase and glutathione reductase. However, glyoxalase I (Glo I) activity was decreased to 20%,, of the control level within 60 min, and was consistently repressed during exposure to GSNO for 20 It. A membrane-permeable Glo I inhibitor, S-bromobenzylglutathione diethylester, inhibited proliferation of ECV304 cells, while methylglyoxal (MG),a toxic metabolite generated during glycolysis and a substrate for Glo I, failed to inhibit the cell growth even at 100 gM. Glo I in several mammalian cell lines was inactivated by GSNO with a pI shift. Although we failed to detect accumulation Of MG Under conditions of Glo I inactivation, these results suggest that the inhibitory effects of GSNO on cell proliferation and DNA synthesis might be at least partly due to inactivation of Glo I. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.