Cyclic AMP inhibits mitogen‐induced DNA synthesis in hamster fibroblasts, regardless of the signalling pathway involved
Open Access
- 13 March 1989
- journal article
- Published by Wiley in FEBS Letters
- Vol. 245 (1-2) , 65-69
- https://doi.org/10.1016/0014-5793(89)80193-0
Abstract
Mitogen‐induced initiation of DNA synthesis in quiescent Chinese hamster lung fibroblasts (CCL39) is strongly inhibited by 8‐Br cAMP and cAMP‐elevating agents (prostaglandin E1, cholera toxin, isobutylmethylxanthine). This inhibition is reversible and occurs very early in G0/G1. As exponential growth is much less affected by increased cAMP, we propose that cAMP inhibits an early signal essential for the exit from G0. CCL39 cells can be stimulated by α‐thrombin, which activates phosphoinositide (PI) ]breakdown, as well as by mitogens (FGF or FGF+serotonin) which do not involve the PI pathway. Here we show that the action of both classes of mitogens is likewise inhibited by cAMP. Therefore, although PI breakdown is inhibited by cAMP in CCL39 cells, this effect cannot entirely account for the antimitogenic activity of cAMP. Other early steps of the mitogenic response must be also affected.Keywords
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