SERUM-STIMULATED CELL-CYCLE PROGRESSION AND STRESS PROTEIN-SYNTHESIS IN C3H10T1 2 FIBROBLASTS TREATED WITH SODIUM ARSENITE/

In this work, we demonstrate that a nonlethal dose of arsenite adminis tered to quiescent C3H10T1/2 fibroblasts can enhance the mitogenic eff ect of suboptimal concentrations of serum. The mitogenic effect was de pendent on the serum concentration and on the time interval between th e administration of arsenite and that of serum. This suggests that mit ogen sensitivity changes in time after arsenite treatment. It is shown that the concentrations of arsenite that enhance the mitogenic effect of serum also increase the mRNA levels of c-fos, HSP68, and HSP84 and induce the specific synthesis of Heat Shock Proteins (HSPs). The phys iological significance of this phenomenon is most likely to counteract the long-term toxic effect of arsenite by early induction of compensa tion for cell loss.