Augmentation of TNF cytotoxicity by protein kinase C inhibitors: role of arachidonic acid and manganese superoxide dismutase

• Published in: Cytokine (Philadelphia, Pa.) Pa.), 1995-08, Vol.7 (6), p.517-525
• Main Authors: Prezioso, Joseph A., Wang, Jue, Kim, Misson, Duty, Lisa, Tweardy, David J., Gorelik, Elieser
• Format: Article
• Language: English
• Subjects: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; Alkaloids - pharmacology; Animals; Antineoplastic Agents - pharmacology; arachidonic acid; Arachidonic Acid - physiology; Drug Resistance, Neoplasm; Drug Synergism; Enzyme Inhibitors - pharmacology; Humans; Indoles - pharmacology; Isoquinolines - pharmacology; Kinetics; Maleimides - pharmacology; Mice; MnSOD; Naphthalenes - pharmacology; Piperazines - pharmacology; PKC inhibitors; Protein Kinase C - antagonists & inhibitors; Staurosporine; Superoxide Dismutase - biosynthesis; Superoxide Dismutase - drug effects; Superoxide Dismutase - physiology; TNF; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha - pharmacology
• ISSN: 1043-4666; 1096-0023
• DOI: 10.1006/cyto.1995.0070

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. The combined results suggest that the potentiation of TNF cytotoxicity by PKC inhibitors in TNF-sensitive cell lines is mediated via the increase in TNF-induced arachidonic acid release and by blocking TNF-mediated induction of MnSOD production.