Effects of selenium on glutathione peroxidase activity and radioprotection in mammalian cells

The media of representative mammalian cell lines were supplemented with low levels of selenium in the form of sodium selenite in order to investigate the effects of selenium on mammalian cells. Following incubation in 30 nM sodium selenite, these cells were assayed for changes in glutathione peroxidase (GPx) activity. The cells examined included NTH 3T3 mouse fibroblasts, PC 12 rat sympathetic precursor cells, SupT‐1 human lymphocytes, MCF‐7 adr human breast carcinoma cells, and AA8 Chinese hamster ovary (CHO) cells. Selenium supplementation resulted in a marginal increase in GPx activity for the NIH 3T3, MCF‐7 adr , and Supt‐1 cells but stimulated GPx activity approximately fivefold in PC 12 and AA8 cells. AA8 cells were selected to evaluate whether selenium supplementation was radioprotective against 60 cobalt gamma irradiation. Protection against radiation‐induced mutation was measured by evaluating mutation frequency at the hprt locus. In this assay, preincubation of AA8 CHO cells significantly protected these cells from exposure to 8 Gy. © 1995 Wiley‐Liss, Inc.