title: Inhibition of p53-mediated growth arrest by overexpression of cyclin-dependent kinases.
abstract: Rat fibroblasts transformed by a temperature-sensitive mutant of murine p53 undergo a reversible growth arrest in G1 at 32.5 degrees C, the temperature at which p53 adopts a wild-type conformation. The arrested cells contain inactive cyclin-dependent kinase 2 (cdk2) despite the presence of high levels of cyclin E and cdk-activating kinase activity. This is due in part to p53-dependent expression of the p2l cdk inhibitor. Upon shift to 39 degrees C, wild-type p53 is lost and cdk2 activation and pRb phosphorylation occur concomitantly with loss of p2l. This p53-mediated growth arrest can be abrogated by overexpression of cdk4 and cdk6 but not cdk2 or cyclins, leading to continuous proliferation of transfected cells in the presence of wild-type p53 and p2l. Kinase-inactive counterparts of cdk4 and cdk6 also rescue these cells from growth arrest, implicating a noncatalytic role for cdk4 and cdk6 in this resistance to p53-mediated growth arrest. Aberrant expression of these cell cycle kinases may thus result in an oncogenic interference with inhibitors of cell cycle progression.
authors: Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors: K M
authors: KM
authors: Latham
authors: S W
authors: SW
authors: Eastman
authors: A
authors: A
authors: Wong
authors: P W
authors: PW
authors: Hinds
mesh_terms: D000818:Animals; D002453:Cell Cycle; D018797:Cell Cycle Proteins; D051358:Cyclin-Dependent Kinase 4; D051361:Cyclin-Dependent Kinase 6; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D016213:Cyclins / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000502:physiology; D017354:Point Mutation; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D011518:Proto-Oncogene Proteins; D051381:Rats; D013696:Temperature; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*; D025521:Tumor Suppressor Proteins
chemical_list: C493957:Cdkn1a protein, mouse; C493958:Cdkn1a protein, rat; C493961:Cdkn1b protein, mouse; C493962:Cdkn1b protein, rat; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D008869:Microtubule-Associated Proteins; D011518:Proto-Oncogene Proteins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D017346:Protein Serine-Threonine Kinases; C495902:Cdk4 protein, mouse; C495903:Cdk4 protein, rat; C495912:Cdk6 protein, mouse; C495913:Cdk6 protein, rat; D051358:Cyclin-Dependent Kinase 4; D051361:Cyclin-Dependent Kinase 6; D018844:Cyclin-Dependent Kinases