title: The c-Jun NH(2)-terminal protein kinase/AP-1 pathway is required for efficient apoptosis induced by vinblastine.
abstract: Vinblastine is an important antitumor agent that induces G(2)-M arrest and subsequent apoptosis in a wide variety of cell lines, but the molecular mechanisms that link mitotic arrest and apoptosis are poorly understood. The AP-1 transcription factor has been implicated in many critical cellular processes, including apoptosis, and is a major target of the c-Jun NH(2)-terminal kinase signaling pathway that is activated by vinblastine and other microtubule inhibitors. In this study we sought to determine the role of c-Jun NH(2)-terminal kinase/AP-1 in the response of KB3 carcinoma cells to vinblastine. For this purpose, we generated KB3 cell lines that stably expressed the c-Jun dominant-negative deletional mutant TAM67, which lacks the NH(2)-terminal transactivation domain. KB3-TAM67 cell lines displayed normal growth kinetics and essentially unaltered basal AP-1 activity, but vinblastine-induced phosphorylation of c-Jun and activating transcription factor-2, and AP-1 activation, were strongly inhibited. KB3-TAM67 cell lines arrested normally at G(2)-M in response to vinblastine, but were significantly more resistant to the drug, exhibiting markedly delayed apoptosis and increased overall survival, relative to control cells. To investigate the underlying mechanisms, differential expression of apoptotic regulatory genes was monitored by immunoblot and cDNA microarray analysis. We found that vinblastine treatment caused down-regulation of p53 and its target p21 and up-regulation of tumor necrosis factor alpha, Bak, and several other genes in control but not in KB3-TAM67 cells, identifying these genes as putative targets of vinblastine-inducible AP-1. These results demonstrate that vinblastine-inducible AP-1 plays a destructive, proapoptotic role and may do so by regulating the expression of a specific subset of target genes that promotes efficient apoptotic cell death following mitotic arrest.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205-7199, USA.
authors.forename: M
authors.initials: M
authors.lastname: Fan
authors.forename: M E
authors.initials: ME
authors.lastname: Goodwin
authors.forename: M J
authors.initials: MJ
authors.lastname: Birrer
authors.forename: T C
authors.initials: TC
authors.lastname: Chambers
mesh_terms: D051698:Activating Transcription Factor 2; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D017362:Cyclic AMP Response Element-Binding Protein / Q000037:antagonists & inhibitors / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000096:biosynthesis / Q000235:genetics; D015536:Down-Regulation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D007624:KB Cells / Q000187:drug effects / Q000473:pathology; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008938:Mitosis / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D017434:Protein Structure, Tertiary; D015398:Signal Transduction / Q000502:physiology; D018808:Transcription Factor AP-1 / Q000096:biosynthesis / Q000502:physiology*; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000378:metabolism; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis / Q000235:genetics; D014747:Vinblastine / Q000494:pharmacology*
chemical_list: C497105:ATF2 protein, human; D051698:Activating Transcription Factor 2; D000972:Antineoplastic Agents, Phytogenic; C493956:CDKN1A protein, human; D017362:Cyclic AMP Response Element-Binding Protein; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D014747:Vinblastine; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases