title: Phosphorylated and hypoacetylated mutant p53 enhances cisplatin-induced apoptosis through caspase-9 pathway in the absence of transcriptional activation or translation.
abstract: It is not completely understood how certain epithelial cells harboring mutant p53 have better response to chemotherapy. We investigate the mechanism of cisplatin-induced apoptosis in two resistant cell lines (parental TCCSUP and R273L mutant p53 transfectant) and two sensitive cell lines (V143A and N247I mutant p53 transfectants). Activation of caspase 9 was demonstrated by Western blotting, and specific inhibitor for caspase 9 could inhibit apoptosis. Inhibitors for caspases 1, 2, 6, and 8 had no effect on apoptosis. Transcriptional repression of Bcl-2 occurred during apoptosis and could be reversed by the treatment of histone deacetylase inhibitor trichostatin A (TSA). The expression of Noxa, p53 inducible ribonucleotide reductase subunit 2 (p53R2), and p53 inducible death domain (PIDD) gene were not elevated with treatment of cisplatin (CDDP). Surface trafficking of Fas or Fas-L was not observed. Ser15 of wild-type p53 and mutant p53 was phosphorylated in response to cisplatin. Acetylation of wild-type p53 increased, while acetylation of mutant p53 decreased during cisplatin treatment. Both transcriptional inhibitor actinomycin D and translational inhibitor cycloheximide did not inhibit apoptosis. These results indicated that phosphorylated and hypoacetylated mutant p53 could enhance cisplatin-induced apoptosis through activation of caspase 9 independent of transcriptional activation and translation.
authors.affiliation: Department of Biochemistry, College of Medicine, National Cheng Kung University, Tainan, Taiwan, Republic of China.
authors.forename: Ming-Derg
authors.initials: MD
authors.lastname: Lai
authors.forename: Wan-Chi
authors.initials: WC
authors.lastname: Lin
authors.forename: Yih-Min
authors.initials: YM
authors.lastname: Sun
authors.forename: Fu-Lin
authors.initials: FL
authors.lastname: Chang
mesh_terms: D000107:Acetylation; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D053453:Caspase 9; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology; D015536:Down-Regulation; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D009154:Mutation; D010766:Phosphorylation; D014176:Protein Biosynthesis / Q000235:genetics / Q000502:physiology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics / Q000502:physiology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D001749:Urinary Bladder Neoplasms / Q000235:genetics / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D061945:Caspase Inhibitors; D056572:Histone Deacetylase Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D012694:Serine; C506433:CASP9 protein, human; D053453:Caspase 9; D020169:Caspases; D002945:Cisplatin