Influence of melatonin on proliferation and antioxidant system in Ehrlich ascites carcinoma cells

The effects of oral supplementation of melatonin on growth of Ehrlich ascit es carcinoma (EAC) cells implanted intraperitoneally in female mice were st udied. Melatonin at 50 mg/kg body wt. reduced the viability and volume of E hrlich ascites carcinoma cells and increased the survival of the treated mi ce. No significant change in intracellular reduced glutathione (GSH) conten t in EAC cells was observed indicating that GSH was not involved in the inh ibitory effect of melatonin. The activity of glutathione-S-transferase in E AC cells was significantly increased. Row cytometirc studies showed that me latonin not only delayed the progression of cells from G(0)/G(1) phase to S -phase of the cell cycle but also reduced DNA synthesis during cell cycle. In addition, the aneuploidy status was depressed in melatonin treated mice. Based on these data and the reduced viability in both in vitro and in vivo , it is suggested that melatonin might induce apoptosis in EAC cells. (C) 2 000 Elsevier Science Ireland Ltd. All rights reserved.