title: Sustained activation of Ras/Raf/mitogen-activated protein kinase cascade by the tumor suppressor p53.
abstract: The p53 tumor suppressor gene can inhibit proliferation transiently, induce permanent cell-cycle arrest/senescence, or cause apoptosis depending on the cellular context. The mitogen-activated protein kinase (MAPK) cascade is known to play a crucial role in cell proliferation and differentiation. Moreover, the duration and intensity of MAPK activation can profoundly influence the biological response observed. We demonstrated that a sustained activation of MAPK cascade could be induced by wild-type p53 expression but not by p21(Waf1/Cip1). Furthermore, exposure of normal cells to DNA-damaging agents induced MAPK activation in a p53-dependent manner. Tumor-derived p53 mutants defective in DNA binding failed to activate MAPK, implying that p53 transcriptional activity is essential for this function. Finally, activation of MAPK by p53 was inhibited by expression of dominant-negative Ras (N17Ras) and Raf1 mutants, indicating that MAPK activation by p53 is mediated at a level upstream of Ras. All of these findings establish a biochemical link between p53 signaling and the Ras/Raf/MAPK cascade.
authors.affiliation: Department of Medicine and Cancer Biology Program, Beth Israel Deaconess Medical Center, Harvard Institutes of Medicine and Harvard Medical School, Boston, MA 02115, USA. slee2@bidmc.harvard.edu
authors.forename: S W
authors.initials: SW
authors.lastname: Lee
authors.forename: L
authors.initials: L
authors.lastname: Fang
authors.forename: M
authors.initials: M
authors.lastname: Igarashi
authors.forename: T
authors.initials: T
authors.lastname: Ouchi
authors.forename: K P
authors.initials: KP
authors.lastname: Lu
authors.forename: S A
authors.initials: SA
authors.lastname: Aaronson
mesh_terms: D002461:Cell Line, Transformed; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D048728:MAP Kinase Kinase Kinase 1; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism*; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D018631:ras Proteins / Q000378:metabolism*
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D016159:Tumor Suppressor Protein p53; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human; D018631:ras Proteins; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one