title: Catalase overexpression impairs TNF-alpha induced NF-kappaB activation and sensitizes MCF-7 cells against TNF-alpha.
abstract: The pleiotropic cytokine tumor necrosis factor alpha (TNF-alpha) can induce apoptosis but also supports cell survival pathways. Among the possible anti-apoptotic mechanisms of TNF-alpha is the activation of the transcription factor NF-kappaB. Since reactive oxygen species (ROS) are assumed to contribute to TNF-alpha mediated cytotoxicity but can also facilitate NF-kappaB activation this study investigates the relationship between TNF-alpha treatment, NF-kappaB activation and the expression of the anti-oxidative enzyme catalase. TNF-alpha treatment caused downregulation of catalase expression in MCF-7, Caco-2 and Hct-116 cancer cell lines. Overexpression of catalase in MCF-7 cells, resulting in lower intracellular ROS levels upon challenge with H(2)O(2), caused a transient nuclear p65 translocation upon TNF-alpha treatment as compared to the sustained NF-kappaB activation in wild type cells. This was due to a lack of sufficient H(2)O(2) to co-stimulate NF-kappaB activation as demonstrated by the observation that addition of exogenous H(2)O(2) led to a second increase of NF-kappaB activity. The rapid decline of nuclear translocation of NF-kappaB in the catalase overexpressing cells resulted in a slower increase of NF-kappaB mediated reporter gene expression. These results indicate that TNF-alpha mediated downregulation of catalase expression and accordingly sufficient H(2)O(2) is required for appropriate function of the NF-kappaB dependent survival pathway.
authors: Institute of Toxicology, Heinrich Heine University of Düsseldorf, P.O. Box 10 10 07, D-40001 Düsseldorf, Germany.
authors: Regine
authors: R
authors: Lüpertz
authors: Yvonni
authors: Y
authors: Chovolou
authors: Andreas
authors: A
authors: Kampkötter
authors: Wim
authors: W
authors: Wätjen
authors: Regine
authors: R
authors: Kahl
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D017209:Apoptosis / Q000187:drug effects*; D018938:Caco-2 Cells; D002374:Catalase / Q000096:biosynthesis* / Q000235:genetics; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D015870:Gene Expression; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D051996:Transcription Factor RelA / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D006861:Hydrogen Peroxide; D002374:Catalase