title: Overexpression of manganese superoxide dismutase suppresses tumor necrosis factor-induced apoptosis and activation of nuclear transcription factor-kappaB and activated protein-1.
abstract: Several recently identified intracellular proteins associate with the tumor necrosis factor (TNF) receptor and activate nuclear transcription factor (NF)-kappaB, c-Jun kinase, and apoptosis. However, the mechanism is not understood. In the present report, we investigated the role of reactive oxygen intermediates in TNF-induced signaling. Overexpression of manganese superoxide dismutase (Mn-SOD) in human breast cancer MCF-7 cells completely abolished TNF-mediated NF-kappaB activation, IkappaB alpha degradation, p65 nuclear translocation, and NF-kappaB-dependent reporter gene expression. Besides TNF, phorbol ester-, okadaic acid-, ceramide-, and lipopolysaccharide-induced activation of NF-kappaB was blocked by Mn-SOD, indicating a common pathway of activation. H2O2-induced NF-kappaB activation, however, was potentiated. In addition, Mn-SOD blocked the TNF-mediated activation of activated protein-1, stress-activated c-Jun protein kinase, and mitogen-activated protein kinase kinase. TNF-induced antiproliferative effects and caspase-3 activation, indicators of apoptosis, were also completely suppressed by transfection of cells with Mn-SOD. Suppression of apoptosis induced by okadaic acid, H2O2, and taxol was also inhibited by Mn-SOD but not that induced by vincristine, vinblastine, or daunomycin. Overall, these results demonstrate that, in addition to several recently identified signaling molecules, reactive oxygen intermediates play a critical role in activation of NF-kappaB, activated protein-1, c-Jun kinase, and apoptosis induced by TNF and other agents.
authors.affiliation: Cytokine Research Section, Department of Molecular Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Manna
authors.forename: H J
authors.initials: HJ
authors.lastname: Zhang
authors.forename: T
authors.initials: T
authors.lastname: Yan
authors.forename: L W
authors.initials: LW
authors.lastname: Oberley
authors.forename: B B
authors.initials: BB
authors.lastname: Aggarwal
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001483:Base Sequence; D006801:Humans; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides; D017382:Reactive Oxygen Species; D015398:Signal Transduction / Q000187:drug effects; D013482:Superoxide Dismutase / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors* / Q000494:pharmacology
chemical_list: D016328:NF-kappa B; D009838:Oligodeoxyribonucleotides; D017382:Reactive Oxygen Species; D018808:Transcription Factor AP-1; D014409:Tumor Necrosis Factor-alpha; D013482:Superoxide Dismutase