Selenium requirements for expression of GPxs in human lung adenocarcinoma cells

Abstract

Selenium (Se), an essential micronutrient, has been proposed to protect against lung cancer. Influence on expression of Se-containing glutathione peroxidases (GPxs) involved in protection from oxidative damage is a possible mode of action. Cell culture media are not usually supplemented with Se. Here we added 0.01 – 2 μ M sodium selenite (Na2SeO3) to culture media and assayed three human lung adenocarcinoma cell lines (H1944, H460 and H1703) and non-transformed peripheral lung epithelial HPL1D cells for GPx1/GPx4 protein levels. Basal GPx1 protein level was lower in all lung cancer lines compared with HPL1D. Se addition resulted in 30- to 40-fold increases in GPx1 protein in H1944 and H460 cells, and an 80% increase in HPL1D cells, with a plateau at 40 nM Na2SeO3 for all three lines. By contrast, in H1703 cells GPx1 was not detected even at 500 nM Na2SeO3, but GPx4 was markedly increased at 40 nM sodium selenite (40-fold), compared with 1.7- to 4-fold in the other lines. Our results indicate that Se supplementation is essential for full expression of GPxs in cultured lung cells, especially cancer cells; that relatively low, clearly non-toxic Se levels are sufficient; and that GPx isoforms respond in specific ways in different cell lines.