title: Inducible overexpression of c-Jun in MCF7 cells causes resistance to vinblastine via inhibition of drug-induced apoptosis and senescence at a step subsequent to mitotic arrest.
abstract: c-Jun is a major component of the AP-1 transcription factor and plays a key role in regulation of diverse biological processes including proliferation and apoptosis. Treatment of a wide variety of cells with the microtubule inhibitor vinblastine leads to a robust increase in c-Jun expression, JNK-mediated c-Jun phosphorylation, and activation of AP-1-dependent transcription. However, the role of c-Jun induction in the response of cells to vinblastine remains obscure. In this study we used MCF7 breast cancer cell lines that express the dominant-negative form of c-Jun, TAM-67, as well as cells that overexpress c-Jun, under the control of an inducible promoter. Vinblastine induced c-Jun protein expression, c-Jun phosphorylation, and AP-1 activation in MCF7 cells, and these parameters were strongly inhibited by inducible TAM-67 expression and strongly enhanced by inducible c-Jun expression. Vinblastine-induced cell death was not affected by TAM-67 expression whereas cells were protected by c-Jun overexpression. Further investigation revealed that apoptotic and senescent cells were observed after vinblastine treatment and that both outcomes were strongly inhibited by c-Jun overexpression. Although c-Jun expression inhibited cell death, it did not affect the ability of vinblastine to induce mitotic arrest. These results indicate that c-Jun expression plays a protective role in the cellular response to vinblastine and operates post-mitotic block to inhibit drug-induced apoptosis and senescence.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Mail Slot 516, 4301 W. Markham Street, Little Rock, AR 72205, United States.
authors.forename: Lingling
authors.initials: L
authors.lastname: Duan
authors.forename: Kristen
authors.initials: K
authors.lastname: Sterba
authors.forename: Sergey
authors.initials: S
authors.lastname: Kolomeichuk
authors.forename: Heetae
authors.initials: H
authors.lastname: Kim
authors.forename: Powel H
authors.initials: PH
authors.lastname: Brown
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Chambers
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D016922:Cellular Senescence / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D005434:Flow Cytometry; D016195:G2 Phase / Q000187:drug effects; D006801:Humans; D015151:Immunoblotting; D008938:Mitosis / Q000187:drug effects*; D010446:Peptide Fragments / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D050257:Tubulin Modulators / Q000494:pharmacology; D014747:Vinblastine / Q000494:pharmacology*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D010446:Peptide Fragments; D016755:Proto-Oncogene Proteins c-jun; C439528:TAM67 peptide; D018808:Transcription Factor AP-1; D050257:Tubulin Modulators; D014747:Vinblastine