title: Cancer-specific enhancement of cisplatin-induced cytotoxicity with triptolide through an interaction of inactivated glycogen synthase kinase-3beta with p53.
abstract: To improve conventional chemotherapeutic efficacy, a combination use of traditional medicines is effective but detailed mechanisms have been rarely elucidated. In the this study, we attempted to clarify how triptolide (PG490), an oxygenated diterpene derived from a Chinese herb, enhances the cisplatin (CDDP)-induced cytotoxicity in urothelial cancer cells. Our results showed that a combined CDDP/triptolide therapy induced apoptosis in urothelial cancer cell lines with wild-type p53, but not in those with mutant-type p53 or normal human urothelium. As the mechanism, triptolide suppressed CDDP-induced p53 transcriptional activity, leading to p21 attenuation, which promoted apoptosis via the activation of c-Jun N-terminal kinase (JNK) and Bax. We further demonstrated that the functional regulation of p53 by triptolide was mediated by an intranuclear association of p53 with glycogen synthase kinase-3beta (GSK3beta), which was inactivated by protein kinase C (PKC). This modulation of the PKC-GSK3beta axis by triptolide was observed in a cancer-specific manner. A mouse xenograft model also showed that a combined CDDP/triptolide therapy completely suppressed tumor growth without any side effects. We expect that cancer-specific enhancement of CDDP-induced cytotoxicity with triptolide may effectively overcome the resistance to a CDDP-based conventional chemotherapy as a treatment for urothelial cancer.
authors.affiliation: Department of Urology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Matsui
authors.forename: J
authors.initials: J
authors.lastname: Watanabe
authors.forename: M
authors.initials: M
authors.lastname: Ikegawa
authors.forename: T
authors.initials: T
authors.lastname: Kamoto
authors.forename: O
authors.initials: O
authors.lastname: Ogawa
authors.forename: H
authors.initials: H
authors.lastname: Nishiyama
mesh_terms: D018906:Antineoplastic Agents, Alkylating / Q000819:agonists / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000819:agonists / Q000494:pharmacology*; D004224:Diterpenes / Q000819:agonists / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor / Q000379:methods; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D004852:Epoxy Compounds / Q000819:agonists / Q000494:pharmacology; D005260:Female; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008297:Male; D009375:Neoplasms, Glandular and Epithelial / Q000188:drug therapy* / Q000378:metabolism*; D010616:Phenanthrenes / Q000819:agonists / Q000494:pharmacology*; D011485:Protein Binding / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D018906:Antineoplastic Agents, Alkylating; C494826:BAX protein, human; D004224:Diterpenes; D004852:Epoxy Compounds; D010616:Phenanthrenes; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; C001899:triptolide; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D011493:Protein Kinase C; D048031:JNK Mitogen-Activated Protein Kinases; D038362:Glycogen Synthase Kinase 3; D002945:Cisplatin