title: Augmentation of TNF cytotoxicity by protein kinase C inhibitors: role of arachidonic acid and manganese superoxide dismutase.
abstract: The protein kinase C (PKC) inhibitors bisindolylmaleimide, calphostin C, H-7 and staurosporine were examined for their effect on tumour necrosis factor (TNF) cytotoxic activity. PKC inhibitors potentiated the cytotoxic activity of TNF in TNF-sensitive cell lines (CL8-1 melanoma and WEHI-164 fibrosarcoma), but had no effect on TNF cytolytic activity in TNF-resistant cells (BL6-8 melanoma and MCA-102 fibrosarcoma). The mechanism(s) of PKC inhibitor-mediated potentiation of the cytotoxic activity of TNF was investigated by analysing the effect of PKC inhibitors on TNF-induced arachidonic acid release in TNF-sensitive and -resistant cells. TNF induced the release of arachidonic acid in TNF-sensitive cells but had no effect in TNF-resistant cells. The combination of PKC inhibitor and TNF potentiated the release of arachidonic acid from TNF-sensitive cells, but failed to induce arachidonic acid release in TNF-resistant cells. Kinetic analysis of TNF-induced arachidonic acid release in CL8-1 melanoma cells revealed that it was an early event which preceded TNF tumour lytic activity. TNF was further shown to induce manganese superoxide dismutase (MnSOD) production in TNF-sensitive cells but failed to induce MnSOD activity in TNF-resistant BL6-8 and MCA 102 cells. MnSOD acts as a scaveneger of toxic superoxide radicals and its induction by TNF paralleled arachidonic acid release. Although the PKC-selective inhibitor bisindolylmaleimide potentiated TNF-induced release of arachidonic acid, it blocked TNF-mediated induction of MnSOD in CL8-1 melanoma and WEHI-164 fibrosarcoma cells.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Pittsburgh Cancer Institute, University of Pittsburgh, PA 15213, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Prezioso
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: M
authors.initials: M
authors.lastname: Kim
authors.forename: L
authors.initials: L
authors.lastname: Duty
authors.forename: D J
authors.initials: DJ
authors.lastname: Tweardy
authors.forename: E
authors.initials: E
authors.lastname: Gorelik
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D016718:Arachidonic Acid / Q000502:physiology*; D019008:Drug Resistance, Neoplasm; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D007700:Kinetics; D008301:Maleimides / Q000494:pharmacology; D051379:Mice; D009281:Naphthalenes / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D019311:Staurosporine; D013482:Superoxide Dismutase / Q000096:biosynthesis / Q000187:drug effects / Q000502:physiology*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D000470:Alkaloids; D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D007211:Indoles; D007546:Isoquinolines; D008301:Maleimides; D009281:Naphthalenes; D010879:Piperazines; D014409:Tumor Necrosis Factor-alpha; D016718:Arachidonic Acid; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D013482:Superoxide Dismutase; D011493:Protein Kinase C; D019311:Staurosporine; C058819:calphostin C; C088060:bisindolylmaleimide