title: Analysis of downstream effectors of p53 on cell growth arrest and apoptosis induced by a temperature-sensitive Val138 mutant.
abstract: To elucidate the mechanism for cell growth arrest in relation to apoptosis mediated by the p53 gene, I studied two p53-null human cancer cell lines (K562 and Jurkat) carrying a human p53 temperature sensitive (ts) mutant (p53138val). The cell growth in the newly established K562 cells carrying the ts mutant was arrested in G0/G1 at the permissive temperature (32.5 degrees C) , at least in part, due to induction of p21/waf1. In apoptosis-induced Jurkat cells upon temperature shift-down, a lower level of p21 induction relative to that of MDM2 was observed in comparison with that in K562 cells. Meanwhile, levels of bax and bcl-2 expression were relatively constant upon temperature shift-down in both cell lines. Studies on the phosphorylation pattern of Rb family proteins, and results of gel-shift and antibody super-shift assays showed the accumulation of Rb/E2F complexes in growth-arrested K562 cells, but no such phenomenon was observed in Jurkat cells. Taken together, the results are consistent with the idea that a higher level of p21 expression and its subsequent Rb/E2F complex formation played an important role in the growth arrest of K562 cells.
authors.affiliation: Department of Molecular & Cellular Oncology and Microbiology, Faculty of Dentistry, Tokyo Medical & Dental University, Japan.
authors.forename: F J
authors.initials: FJ
authors.lastname: Wang
mesh_terms: D017209:Apoptosis / Q000235:genetics*; D015153:Blotting, Western; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002455:Cell Division / Q000235:genetics*; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000096:biosynthesis; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D004591:Electrophoresis, Polyacrylamide Gel; D005434:Flow Cytometry; D016193:G1 Phase / Q000235:genetics; D015973:Gene Expression Regulation, Leukemic; D016158:Genes, p53 / Q000502:physiology*; D006801:Humans; D019169:Jurkat Cells; D020014:K562 Cells; D009154:Mutation; D009687:Nuclear Proteins; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D051736:Proto-Oncogene Proteins c-mdm2; D016283:Proto-Oncogene Proteins p21(ras) / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid / Q000502:physiology*; D016160:Retinoblastoma Protein / Q000378:metabolism; D056465:Retinoblastoma-Binding Protein 1; D013696:Temperature; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000378:metabolism; D051028:bcl-2-Associated X Protein
chemical_list: C494826:BAX protein, human; C493956:CDKN1A protein, human; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016160:Retinoblastoma Protein; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors; D051028:bcl-2-Associated X Protein; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D016283:Proto-Oncogene Proteins p21(ras)