title: p53-induced apoptosis occurs in the absence of p14(ARF) in malignant pleural mesothelioma.
abstract: Malignant pleural mesotheliomas (MPMs) are usually wild type for the p53 gene but contain homozygous deletions in the INK4A locus that encodes p14(ARF), an inhibitor of p53-MDM2 interaction. Previous findings suggest that lack of p14(ARF) expression and the presence of SV40 large T antigen (L-Tag) result in p53 inactivation in MPM. We did not detect SV40 L-Tag mRNA in either MPM cell lines or primary cultures, and treatment of p14(ARF)-deficient cells with cisplatin (CDDP) increased both total and phosphorylated p53 and enhanced p53 DNA-binding activity. On incubation with CDDP, levels of positively regulated p53 transcriptional targets p21(WAF), PIG3, MDM2, Bax, and PUMA increased in p14(ARF)-deficient cells, whereas negatively regulated survivin decreased. Significantly, p53-induced apoptosis was activated by CDDP in p14(ARF)-deficient cells, and treatment with p53-specific siRNA rendered them more CDDP-resistant. p53 was also activated by: 1) inhibition of MDM2 (using nutlin-3); 2) transient overexpression of p14(ARF); and 3) targeting of survivin using antisense oligonucleotides. However, it is noteworthy that only survivin downregulation sensitized cells to CDDP-induced apoptosis. These results suggest that p53 is functional in the absence of p14(ARF) in MPM and that targeting of the downstream apoptosis inhibitor survivin can sensitize to CDDP-induced apoptosis.
authors.affiliation: Laboratory for Molecular Oncology, University Hospital Zurich, Haeldeliweg 4, CH-8044 Zurich, Switzerland. sally.donaldson@usz.ch
authors.forename: Sally
authors.initials: S
authors.lastname: Hopkins-Donaldson
authors.forename: Larisa L
authors.initials: LL
authors.lastname: Belyanskaya
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Simões-Wüst
authors.forename: Brigitte
authors.initials: B
authors.lastname: Sigrist
authors.forename: Stefanie
authors.initials: S
authors.lastname: Kurtz
authors.forename: Uwe
authors.initials: U
authors.lastname: Zangemeister-Wittke
authors.forename: Rolf
authors.initials: R
authors.lastname: Stahel
mesh_terms: D017209:Apoptosis; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002945:Cisplatin / Q000494:pharmacology; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D016158:Genes, p53; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D008654:Mesothelioma / Q000378:metabolism* / Q000473:pathology; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D010997:Pleural Neoplasms / Q000378:metabolism* / Q000473:pathology; D017422:Sequence Analysis, DNA; D000077022:Survivin; D025803:Tumor Suppressor Protein p14ARF / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*
chemical_list: C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D000077022:Survivin; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D002945:Cisplatin