title: Aberrant p53 alters DNA damage checkpoints in response to cisplatin: downregulation of CDK expression and activity.
abstract: The p53 tumor suppressor protein is a critical mediator of cell cycle arrest and apoptosis in response to genotoxic stress. Abrogation of p53 function is a major feature of tumor development and may result in a compromised DNA-damage response. In our study, we examined the effect of expressing a human p53 cDNA, encoding a histidine to leucine amino acid substitution at codon 179 (H179L), on the ability of wild-type p53-containing NIH3T3 cells to respond to treatment with the chemotherapeutic cisplatin. After 72 hr of cisplatin treatment control cells underwent apoptosis preceded by a combination of S- and G(2) arrest, as judged by flow cytometry of propidium iodide-stained cells, and TUNEL and caspase-3 assays. This correlated with increased expression of the pro-apoptotic protein Bax. In contrast, cells stably expressing H179L-p53 arrested in S-phase following cisplatin treatment, which correlated with a marked decrease in the expression of cdc2, cyclin B1 and cyclin A, and a decrease in CDK2 and cyclin A-associated kinase activity. Interestingly, H179L p53 expressing cells underwent apoptosis earlier than control cells, indicating that this aberrant p53 may enhance cisplatin chemosensitivity. These data suggest that dominant-negative p53 can influence the expression and activity of CDK complexes, thereby modifying cell behavior following cisplatin-induced genotoxicity.
authors.affiliation: Head and Neck Cancer Program, King's College London, London, United Kingdom.
authors.forename: Katharine H
authors.initials: KH
authors.lastname: Wrighton
authors.forename: Cecilia M
authors.initials: CM
authors.lastname: Prêle
authors.forename: Andrew
authors.initials: A
authors.lastname: Sunters
authors.forename: W Andrew
authors.initials: WA
authors.lastname: Yeudall
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000473:pathology; D002453:Cell Cycle; D002945:Cisplatin / Q000494:pharmacology*; D018844:Cyclin-Dependent Kinases / Q000096:biosynthesis*; D004249:DNA Damage; D004260:DNA Repair; D018076:DNA, Complementary; D015536:Down-Regulation; D005347:Fibroblasts; D005434:Flow Cytometry; D018816:Genes, cdc; D006801:Humans; D020287:In Situ Nick-End Labeling; D051379:Mice; D017354:Point Mutation; D014183:Transplantation, Heterologous; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; D018076:DNA, Complementary; D016159:Tumor Suppressor Protein p53; D018844:Cyclin-Dependent Kinases; D002945:Cisplatin