title: On the regulation of DNA synthesis in a line of adrenocortical tumor cells: effect of serum, adrenocorticotropin and pituitary factors.
abstract: Y-1 adrenal cells responded to serum step down by a several fold decrease in DNA synthesis. Serum starved cells resumed DNA synthesis upon serum step up. ACTH and cAMP inhibited DNA synthesis both at low and high serum concentrations, a fact previously known. Pituitary, brain and liver crude extracts stimulated DNA synthesis in serum starved cells. Purified pituitary factors preparations contained two activities: one specific for Y-1 cells and another active with both fibroblasts and Y-1 cells. The kinetics of restimulation of DNA synthesis by serum and pituitary factors was studied. DNA synthesis restimulation occurred after a lag of 11 hours. This lag did not vary irrespective of the type of stimulator or its concentration. Cells entered S phase continuously at a rate which increased with increasing concentrations of the stimulator. Cells became refractory to the inhibitory action of ACTH five hours before entering S phase. The implications of these data to the understanding of cell growth control are considered.
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000494:pharmacology*; D001769:Blood; D001921:Brain; D002453:Cell Cycle; D002460:Cell Line; D000242:Cyclic AMP / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis*; D006854:Hydrocortisone / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D008110:Liver Extracts / Q000494:pharmacology; D010902:Pituitary Gland; D014020:Tissue Extracts / Q000494:pharmacology*
chemical_list: D007328:Insulin; D008110:Liver Extracts; D014020:Tissue Extracts; D000324:Adrenocorticotropic Hormone; D004247:DNA; D000242:Cyclic AMP; D006854:Hydrocortisone