title: Tumor necrosis factor-alpha up-regulates Bcl-2 expression and decreases calcium-dependent apoptosis in human B cell lines.
abstract: Group I and Epstein-Barr virus-negative Burkitt's lymphoma cell lines and the B104 lymphoma cell line which expresses a phenotype of immature B cells undergo apoptosis after cross-linking of their surface Ig receptors or after exposure to a calcium ionophore. We show here that tumor necrosis factor (TNF)-alpha protects these B cell lines against Ca(2+)-dependent apoptosis. Protection was associated with up-regulation of bcl-2 mRNA and protein expression. The increase of Bcl-2 expression induced by TNF-alpha was inhibited by chelerythrine, a specific inhibitor of protein kinase C (PKC), suggesting that Bcl-2 expression was dependent on PKC activation. Furthermore, we show that phorbol esters and cyclosporin A (CsA), which prevent Ca(2+)-dependent apoptosis, up-regulated Bcl-2 expression. The effect of CsA on Bcl-2 expression is controlled by calcineurin since we have shown that FK506 but not rapamycin had the same effect on Bcl-2 expression, whereas okadaic acid, an inhibitor of phosphatases 1, 2A and 2C, was ineffective. These data provide direct evidence that TNF-alpha prevents Ca(2+)-dependent apoptosis by a Bcl-2-dependent mechanism mediated by PKC.
authors.affiliation: Laboratories of Immunology (INSERM U.80), Hôpital E. Herriot, Lyon, France.
authors.forename: L
authors.initials: L
authors.lastname: Genestier
authors.forename: N
authors.initials: N
authors.lastname: Bonnefoy-Berard
authors.forename: J P
authors.initials: JP
authors.lastname: Rouault
authors.forename: M
authors.initials: M
authors.lastname: Flacher
authors.forename: J P
authors.initials: JP
authors.lastname: Revillard
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001402:B-Lymphocytes / Q000378:metabolism*; D019703:Calcineurin; D002118:Calcium / Q000037:antagonists & inhibitors / Q000502:physiology*; D002148:Calmodulin-Binding Proteins / Q000494:pharmacology; D002460:Cell Line; D016572:Cyclosporine / Q000494:pharmacology; D004789:Enzyme Activation; D006801:Humans; D010749:Phosphoprotein Phosphatases / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis* / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*; D015854:Up-Regulation
chemical_list: D002148:Calmodulin-Binding Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D014409:Tumor Necrosis Factor-alpha; D016572:Cyclosporine; D011493:Protein Kinase C; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium