Cell cycle progression of C3H 10T1/2 and 3T3 cells in the absence of an increase in c-myc RNA levels.
Normally, when confluent cells are stimulated to divide, they show a transient increase in c-myc RNA levels (1-5). This has led many investigators to believe that the rise in c-myc RNA is causally related to the control and regulation of cell proliferation. However, we report here that the rise in c-myc RNA levels is not observed in stimulated cycling C3H 10T1/2 and 3T3 cells that have been grown to confluence in the presence of the protease inhibitor antipain. Cells continue to progress from the G0/G1 phase to S phase of the cell cycle in the absence of an increase in c-myc RNA; the kinetics of [3H]thymidine incorporation after serum stimulation are comparable to those observed in cells in which c-myc RNA levels rise after serum stimulation. Our observations are of significance because they suggest a dissociation between the transient rise of c-myc RNA which occurs before DNA synthesis and the events that initiate DNA synthesis in quiescent fibroblasts; c-myc may not play as central a role in stimulating noncycling, quiescent cells to progress through the cell cycle, as has been generally assumed.
D000818:Animals; D000976:Antipain / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division; D004261:DNA Replication; D005347:Fibroblasts; D005786:Gene Expression Regulation / Q000187:drug effects*; D051379:Mice; D008809:Mice, Inbred C3H; D009842:Oligopeptides / Q000494:pharmacology*; D009857:Oncogenes; D012313:RNA / Q000378:metabolism*
D009842:Oligopeptides; D000976:Antipain; D012313:RNA