Metabolism of selenomethionine and effects of interacting compounds by mammalian cells in culture.

Since differences have been found in animals, the efficacies of selenomethionine (SeMet), selenite, and selenocystine (SeCys) for glutathione peroxidase (GPx) induction and cellular incorporation were compared and some effects of interacting nutrients on SeMet utilization were examined in tissue cultures. In three cell lines, Chang liver cells, mouse myoblasts and human fibroblasts, selenite was more effective than SeMet for GPx induction. However, radiotracer studies showed that SeMet was more rapidly incorporated into all cells than either selenite or SeCys. Chromatography of acid hydrolysates of Chang liver cells grown with 75Se-labeled SeMet indicated that approximately 90% of incorporated 75Se remained as SeMet, and less than 10% was as SeCys, the form of Se in GPx. Selenite supplementation slightly reduced both the incorporation of 75SeMet and the proportion of cellular 75Se recoverable as SeCys in Chang liver cells. Supplementation with L-methionine, however, significantly reduced 75SeMet incorporation, but significantly increased the proportion of cellular 75Se recovered as SeCys. L-cystine supplementation had no effect on either the cellular incorporation of 75SeMet or the proportion of cellular 75Se recovered as SeCys. These studies of SeMet utilization and effects of interacting nutrients are reflective of observations on SeMet metabolism in whole animals and humans.