The Effects of Sodium Selenite on the Antioxidative Defence Mechanism of Human Hepatoma G_2 Cells

Authors: KAYAHAN FIŞKIN

Abstract: Human cells that live in biological harmony can become cancerous. As they do so, they engage in anaerobic respiration, undergo rapid cell growth and division according to nonmitotic rules, and important changes take place in their metabolism. We conducted several investigations in an effort to block or change the metabolic characteristics of cancer cells using a typical cancerous cell line. Specifically,we investigated the effects of sodium selenite (Na_2 SeO_ 3 ) on antioxidant enzyme activities and reduced glutathione levels in Hepatoma G_ 2 cells, cells that show rapid glutamine uptake and metabolism. A Hepatoma G_ 2 cell line was cultured in RPMI 1640 Dutch medium. Sodium selenite solution was added to the culture medium to produce a final concentration of 1µM/ml on the second day of incubation and several measurements of metabolic activity were taken.The selenium treatment increased selenium-dependent glutathione peroxidase and Cu,Zn super oxide dismutase activities by approximately 100% and 21% respectively, yet reduced catalase activity by 20%. There was no Mn-super oxide dismutase activity in the Hepatoma G_2 cells, but the existence of an inactive form of Mn-super oxide dismutase was observed. Glutathione S-transferase activity was not affected by selenium. Selenium caused a 56% decrease in reduced glutathione level in a Hepatoma G_2 cell line. We argue that the observed changes are due to selenium dependent protein as a Se-GSH-Px. The unchanging activity levels of glutathione-S transferase is important because it plays a key role in cellular detoxification mechanisms. We conclude that glutathione metabolism in cancer cells slows with selenium treatment.

Keywords: Hepatoma G_2 , Sodium selenite, Glutathione peroxidase, Catalase, Superoxide dismutase.

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