title: p53 activates the CD95 (APO-1/Fas) gene in response to DNA damage by anticancer drugs.
abstract: Chemotherapeutic drugs cause DNA damage and kill cancer cells mainly by apoptosis. p53 mediates apoptosis after DNA damage. To explore the pathway of p53-dependent cell death, we investigated if p53-dependent apoptosis after DNA damage is mediated by the CD95 (APO-1/Fas) receptor/ligand system. We investigated hepatoma, gastric cancer, colon cancer, and breast cancer cell lines upon treatment with different anticancer agents known to act via p53 accumulation. Cisplatin, mitomycin, methotrexate, mitoxantrone, doxorubicin, and bleomycin at concentrations present in the sera of patients during therapy led to an upregulation of both CD95 receptor and CD95 ligand. Induction of the CD95 ligand occurred in p53 wild-type (wt), p53 mutant (mt), and p53 deficient (p53(-/-)) cell lines and at wt and mt conformation of temperature-sensitive p53 mutants. In contrast, upregulation of the CD95 receptor was observed only in cells with wt p53, not in cells with mt or without any p53. Restitution of inducible wt p53 function restored the ability of p53(-/-) Hep3B cells to upregulate the CD95 receptor in response to anticancer drugs. This rendered the cells sensitive to CD95-mediated apoptosis. In an attempt to understand how CD95 expression is regulated by p53, we identified a p53-responsive element within the first intron of the CD95 gene, as well as three putative elements within the promoter. The intronic element conferred transcriptional activation by p53 and cooperated with p53-responsive elements in the promoter of the CD95 gene. wt p53 bound to and transactivated the CD95 gene, whereas mt p53 failed to induce apoptosis via activation of the CD95 gene. These observations provide a mechanistic explanation for the ability of p53 to contribute to tumor progression and to resistance of cancer cells to chemotherapy.
authors.affiliation: Department of Internal Medicine IV, Hepatology and Gastroenterology, University Hospital, 69115 Heidelberg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Müller
authors.forename: S
authors.initials: S
authors.lastname: Wilder
authors.forename: D
authors.initials: D
authors.lastname: Bannasch
authors.forename: D
authors.initials: D
authors.lastname: Israeli
authors.forename: K
authors.initials: K
authors.lastname: Lehlbach
authors.forename: M
authors.initials: M
authors.lastname: Li-Weber
authors.forename: S L
authors.initials: SL
authors.lastname: Friedman
authors.forename: P R
authors.initials: PR
authors.lastname: Galle
authors.forename: W
authors.initials: W
authors.lastname: Stremmel
authors.forename: M
authors.initials: M
authors.lastname: Oren
authors.forename: P H
authors.initials: PH
authors.lastname: Krammer
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001483:Base Sequence; D004249:DNA Damage / Q000187:drug effects* / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D008969:Molecular Sequence Data; D009369:Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*; D019014:fas Receptor / Q000235:genetics*
chemical_list: D000970:Antineoplastic Agents; D016159:Tumor Suppressor Protein p53; D019014:fas Receptor