title: c-Jun NH2-terminal kinase-mediated up-regulation of death receptor 5 contributes to induction of apoptosis by the novel synthetic triterpenoid methyl-2-cyano-3,12-dioxooleana-1, 9-dien-28-oate in human lung cancer cells.
abstract: Death receptor (DR) 4 or 5, on binding to its ligand, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), triggers apoptosis via activating the caspase-8-mediated caspase cascade. Certain anticancer drugs up-regulate the expression of these receptors and thereby induce apoptosis or enhance TRAIL-induced apoptosis. In this study, we explored the ability of methyl-2-cyano-3,12-dioxooleana-1,9-dien-28-oate (CDDO-Me) to activate the extrinsic DR-mediated apoptotic pathway in human lung cancer cells. We found that CDDO-Me not only activated caspase-8 but also induced expression of DRs, particularly DR5, in a p53-independent mechanism. Correspondingly, CDDO-Me augmented TRAIL-induced apoptosis in these cells regardless of p53 status as evidenced by enhanced DNA fragmentation and activation of caspase cascades, suggesting that CDDO-Me-induced DRs are functionally active. Moreover, silencing of DR5 expression using small interfering RNA suppressed apoptosis induced by CDDO-Me alone or by combination of CDDO-Me and TRAIL, indicating that DR5 up-regulation is required for induction of apoptosis by CDDO-Me and for enhancement of TRAIL-induced apoptosis by CDDO-Me. CDDO-Me rapidly activated c-Jun NH(2)-terminal kinase (JNK) before DR up-regulation and caspase-8 activation. Moreover, application of the JNK-specific inhibitor SP600125 blocked CDDO-Me-induced increases in JNK activation, DR up-regulation, caspase-8 activation, and DNA fragmentation. These results show that activation of JNK pathway results in CDDO-Me-induced DR up-regulation, caspase-8 activation, and apoptosis. Collectively, we conclude that CDDO-Me induces apoptosis via the JNK-mediated DR up-regulation in human lung cancer cells.
authors.affiliation: Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Zou
authors.forename: Xiangguo
authors.initials: X
authors.lastname: Liu
authors.forename: Ping
authors.initials: P
authors.lastname: Yue
authors.forename: Zhongmei
authors.initials: Z
authors.lastname: Zhou
authors.forename: Michael B
authors.initials: MB
authors.lastname: Sporn
authors.forename: Reuben
authors.initials: R
authors.lastname: Lotan
authors.forename: Fadlo R
authors.initials: FR
authors.lastname: Khuri
authors.forename: Shi-Yong
authors.initials: SY
authors.lastname: Sun
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D051017:Apoptosis Regulatory Proteins; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology*; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism / Q000502:physiology*; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology*; D008562:Membrane Glycoproteins / Q000008:administration & dosage / Q000494:pharmacology; D009828:Oleanolic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology*; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000096:biosynthesis* / Q000235:genetics; D015398:Signal Transduction; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: D051017:Apoptosis Regulatory Proteins; D008562:Membrane Glycoproteins; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C105190:TNFRSF10A protein, human; C505639:TNFRSF10B protein, human; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D009828:Oleanolic Acid; C445068:bardoxolone methyl; D048031:JNK Mitogen-Activated Protein Kinases; C505530:CASP8 protein, human; D053181:Caspase 8; D020169:Caspases