title: NF-kappaB activation represses tumor necrosis factor-alpha-induced autophagy.
abstract: Activation of NF-kappaB and autophagy are two processes involved in the regulation of cell death, but the possible cross-talk between these two signaling pathways is largely unknown. Here, we show that NF-kappaB activation mediates repression of autophagy in tumor necrosis factor-alpha (TNFalpha)-treated Ewing sarcoma cells. This repression is associated with an NF-kappaB-dependent activation of the autophagy inhibitor mTOR. In contrast, in cells lacking NF-kappaB activation, TNFalpha treatment up-regulates the expression of the autophagy-promoting protein Beclin 1 and subsequently induces the accumulation of autophagic vacuoles. Both of these responses are dependent on reactive oxygen species (ROS) production and can be mimicked in NF-kappaB-competent cells by the addition of H2O2. Small interfering RNA-mediated knockdown of beclin 1 and atg7 expression, two autophagy-related genes, reduced TNFalpha- and reactive oxygen species-induced apoptosis in cells lacking NF-kappaB activation and in NF-kappaB-competent cells, respectively. These findings demonstrate that autophagy may amplify apoptosis when associated with a death signaling pathway. They are also evidence that inhibition of autophagy is a novel mechanism of the antiapoptotic function of NF-kappaB activation. We suggest that stimulation of autophagy may be a potential way bypassing the resistance of cancer cells to anti-cancer agents that activate NF-kappaB.
authors.affiliation: INSERM U756, Faculté de Pharmacie, Université Paris-Sud 11, 5 Rue Jean-Baptiste Clément, 92296 Châtenay-Malabry, France. mojgan.mergny@cep.u-psud.fr
authors.forename: Mojgan
authors.initials: M
authors.lastname: Djavaheri-Mergny
authors.forename: Manuela
authors.initials: M
authors.lastname: Amelotti
authors.forename: Julie
authors.initials: J
authors.lastname: Mathieu
authors.forename: Françoise
authors.initials: F
authors.lastname: Besançon
authors.forename: Chantal
authors.initials: C
authors.lastname: Bauvy
authors.forename: Sylvie
authors.initials: S
authors.lastname: Souquère
authors.forename: Gérard
authors.initials: G
authors.lastname: Pierron
authors.forename: Patrice
authors.initials: P
authors.lastname: Codogno
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001343:Autophagy; D000071186:Beclin-1; D002103:Cadaverine / Q000031:analogs & derivatives / Q000494:pharmacology; D045744:Cell Line, Tumor; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D052002:NF-kappa B p50 Subunit / Q000378:metabolism*; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; C491997:BECN1 protein, human; D000071186:Beclin-1; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; C489548:NFKB1 protein, human; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D006861:Hydrogen Peroxide; C008542:monodansylcadaverine; D002103:Cadaverine