title: Ras- and mitogen-activated protein kinase kinase-dependent and -independent pathways in p21Cip1/Waf1 induction by fibroblast growth factor-2, platelet-derived growth factor, and transforming growth factor-beta1.
abstract: p21(Waf1/Cip1) (hereafter referred to as p21) is up-regulated in differentiating and DNA-damaged cells, but it is also up-regulated by serum and growth factors. We show here that fibroblast growth factor-2 (FGF-2), platelet-derived growth factor (PDGF), and transforming growth factor-beta1 (TGF-beta1) all induce p21 expression in mouse fibroblasts, but with markedly different kinetics. We link their effect on p21 to Ras and mitogen-activated protein kinase kinase-1(/2) [MEK1(/2)]-regulated pathways using either a specific MEK1(/2) inhibitor (PD 098059) or cells expressing conditionally activated Ras or dominant negative Ras. We demonstrate that p21 induction by PDGF and TGF-beta1 requires MEK1(/2) and, additionally, that the TGF-beta1 effect on p21 depends on Ras, whereas the PDGF effect does not. In contrast, FGF-2 regulation of p21 is largely independent of MEK and Ras. However, PD 098059 efficiently inhibited S-phase entry of quiescent cells induced by either FGF-2 or PDGF, suggesting separate signaling pathways for FGF-2 in induction of p21 and in S-phase entry. The results suggest different but partly overlapping signaling pathways in growth factor regulation of p21.
authors.affiliation: Haartman Institute, Department of Virology, University of Helsinki, Finland.
authors.forename: L
authors.initials: L
authors.lastname: Kivinen
authors.forename: M
authors.initials: M
authors.lastname: Laiho
mesh_terms: D016475:3T3 Cells; D000818:Animals; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006133:Growth Substances / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics; D048369:MAP Kinase Kinase 1; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000378:metabolism / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases; D012333:RNA, Messenger / Q000032:analysis; D016196:S Phase / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D018631:ras Proteins / Q000378:metabolism*
chemical_list: C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D006133:Growth Substances; D010982:Platelet-Derived Growth Factor; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D016222:Fibroblast Growth Factor 2; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases; D018631:ras Proteins; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one