title: Down-regulation of X-linked inhibitor of apoptosis protein induces apoptosis in chemoresistant human ovarian cancer cells.
abstract: Cisplatin-centered chemotherapy is a key treatment for ovarian cancer, but resistance to chemotherapeutic agents remains a major cause of treatment failure. Multiple factors are known to contribute to the development of this chemoresistance. Although it has been demonstrated that X-linked inhibitor of apoptosis protein (Xiap) prevents apoptosis by inhibiting effector caspases, if and how it is important in chemoresistance in ovarian cancer has not been studied. The effects of Xiap down-regulation and/or restoration of wild type p53 by recombinant adenovirus infection were examined on four ovarian epithelial cancer cell lines [C13*, A2780-s (wild type p53), A2780-cp (mutant p53), and SKOV3 (null p53)]. Apoptosis and protein expression (e.g., Xiap, caspase-3, p53, MDM2, and p21waf1) were assessed by Hoechst 33258 stain and Western blot, respectively. We demonstrated that Xiap down-regulation following adenoviral antisense expression induces apoptosis in the wild-type p53 cells, but not in the mutated or null cells. Xiap down-regulation resulted in caspase-3 activation, caspase-mediated MDM2 processing, and p53 accumulation. Restoration of wild type p53 in the p53-mutated or -null cells significantly enhanced the proapoptotic effect of Xiap antisense expression. Down-regulation of Xiap induced apoptosis in chemoresistant ovarian cancer cells, a process dependent on p53 status.
authors.affiliation: Department of Obstetrics and Gynaecology, University of Ottawa, and Loeb Health Research Institute, The Ottawa Hospital, Ontario, Canada.
authors.forename: H
authors.initials: H
authors.lastname: Sasaki
authors.forename: Y
authors.initials: Y
authors.lastname: Sheng
authors.forename: F
authors.initials: F
authors.lastname: Kotsuji
authors.forename: B K
authors.initials: BK
authors.lastname: Tsang
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000235:genetics / Q000473:pathology; D000256:Adenoviridae / Q000235:genetics; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002945:Cisplatin / Q000494:pharmacology*; D018284:Cystadenocarcinoma, Serous / Q000188:drug therapy / Q000235:genetics / Q000473:pathology; D018076:DNA, Complementary / Q000235:genetics; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D005822:Genetic Vectors; D006801:Humans; D009363:Neoplasm Proteins / Q000378:metabolism; D009687:Nuclear Proteins; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000494:pharmacology; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D051636:X-Linked Inhibitor of Apoptosis Protein
chemical_list: D000970:Antineoplastic Agents; D018076:DNA, Complementary; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D016376:Oligonucleotides, Antisense; D011506:Proteins; D011518:Proto-Oncogene Proteins; D016159:Tumor Suppressor Protein p53; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D002945:Cisplatin