The influence of insulin in the cell cycle of human aging cells.
Normal human IMR 90 fibroblasts at population doubling levels (PDL) 28 approximately 33 had an increased incorporation of 3H-thymidine into DNA when the cells were pretreated with physiologic concentrations of insulin (5 approximately 10 ng/ml) prior to re-initiation of the cell cycle. Insulin stimulation was not observed with fibroblasts at PDL 50 nor with SV40 virus transformed cells. In all cells treated with supra-physiologic concentrations of insulin (1000 approximately 6000 ng/ml) prior to the re-initiation of cell cycle, the incorporation of thymidine into DNA was greatly diminished. Autoradiographic studies of the effect of insulin suggest that a larger fraction of cells was found to enter S phase than untreated cultures. This effect was evident in younger cells rather than senescent cells.
D001345:Autoradiography; D002453:Cell Cycle; D002470:Cell Survival; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D005347:Fibroblasts / Q000166:cytology*; D006801:Humans; D007328:Insulin / Q000502:physiology*; D013936:Thymidine / Q000378:metabolism
D007328:Insulin; D004247:DNA; D013936:Thymidine