title: Resistance to tumor necrosis factor-alpha (TNF-alpha)-induced apoptosis in rat hepatoma cells expressing TNF-alpha is linked to low antioxidant enzyme expression.
abstract: In order to study the mechanisms of resistance to tumor necrosis factor-alpha (TNF-alpha), we have constructed two stable transfectants producing TNF-alpha (Yv12-2 and Yv13-44) from the rat hepatoma H4IIE cell, which does not produce TNF-alpha. H4IIE cells were highly sensitive to apoptosis induced by TNF-alpha, whereas Yv2-12 and Yv13-44 cells were resistant. Manganous superoxide dismutase was not up-regulated in Yv2-12 and Yv13-44 cells and was unresponsive to induction by exogenous TNF-alpha and by H2O2 in H4IIE cells and in the transfectants. Catalase expression and activity were lower in Yv2-12 and Yv13-44 cells than in H4IIE cells; furthermore, the transfectants were more susceptible to H2O2. Treatment with exogenous TNF-alpha down-regulated catalase in H4IIE cells but not in Yv2-12 and Yv13-44 cells. Treatment of H4IIE cells with the catalase inhibitor 3-amino-1,2,4-triazole rendered them resistant to exogenous TNF-alpha. These data suggest a causal relationship between resistance to TNF-alpha and low catalase activity. Expression of copper and zinc containing superoxide dismutase was also decreased, whereas expression of glutathione peroxidase-1 was unchanged in Yv2-12 and Yv13-44 cells. Data from a microarray point to a down-regulation of genes in the resistant clones that code for antioxidative proteins and proteins involved in glutathione synthesis and function. We assume that a prooxidant signal linked to the down-regulation of antioxidant defense may be associated with resistance to apoptosis induced by TNF-alpha.
authors.affiliation: Institute of Toxicology, Heinrich Heine University of Duesseldorf, P. O. Box 10 10 07, D-40001 Duesseldorf, Germany.
authors.forename: Yvonni
authors.initials: Y
authors.lastname: Chovolou
authors.forename: Wim
authors.initials: W
authors.lastname: Watjen
authors.forename: Andreas
authors.initials: A
authors.lastname: Kampkotter
authors.forename: Regine
authors.initials: R
authors.lastname: Kahl
mesh_terms: D000640:Amitrole / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D017209:Apoptosis; D015152:Blotting, Northern; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000201:enzymology / Q000378:metabolism*; D002374:Catalase / Q000037:antagonists & inhibitors / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival; D003300:Copper / Q000378:metabolism; D053938:DNA Fragmentation; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051379:Mice; D020411:Oligonucleotide Array Sequence Analysis; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013482:Superoxide Dismutase / Q000096:biosynthesis; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D015854:Up-Regulation; D015032:Zinc / Q000378:metabolism
chemical_list: D000975:Antioxidants; D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D014409:Tumor Necrosis Factor-alpha; D003300:Copper; D006861:Hydrogen Peroxide; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D005978:Glutathione; D015032:Zinc; D000640:Amitrole