PROTEIN-SYNTHESIS IS NOT REQUIRED FOR THE INHIBITORY EFFECT OF SELENITE ON CELL COLONY FORMATION AND RNA-SYNTHESIS

Selenite has been shown to undergo intracellular metabolism that resul ts in its conversion to other low molecular weight Se-containing speci es and also to its incorporation into a selenocysteine residue in sele noprotein. In order to investigate whether the incorporation into prot ein is required for the cytotoxic effects of selenite, we have examine d whether inhibition of protein synthesis prevents the inhibitory effe ct of selenite on the ability of cells to form colonies or to synthesi ze RNA. We have found that treatment of HeLa cells with cycloheximide inhibited protein synthesis by > 90% but had no effect on the inhibito ry effect of selenite on cell colony formation or RNA synthesis. Since protein synthesis is not necessary for these cytotoxic effects of sel enite they are unlikely to result from an increase in the synthesis of selenoproteins.