Tumor necrosis factor gene expression is mediated by protein kinase C following activation by ionizing radiation

• Published in: Cancer research (Chicago, Ill.) Vol. 51; no. 17; pp. 4565 - 4569
• Main Authors: HALLAHAN, D. E, VIRUDACHALAM, S, SHERMAN, M. L, HUBERMAN, E, KUFE, D. W, WEICHSELBAUM, R. R
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 01.09.1991
• Subjects: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; Biological and medical sciences; Cell Line; Down-Regulation; Enzyme Activation; Gene Expression Regulation - radiation effects; Isoquinolines - pharmacology; Medical sciences; Phosphorylation; Piperazines - pharmacology; Protein Kinase C - antagonists & inhibitors; Protein Kinase C - metabolism; Radiation therapy and radiosensitizing agent; Signal Transduction; Sulfonamides; Tetradecanoylphorbol Acetate - pharmacology; Transcription, Genetic; Treatment with physical agents; Treatment. General aspects; Tumor Necrosis Factor-alpha - genetics; Tumors; Protein kinase C; Enzyme; Cytokine; Cytotoxicity; Malignant hemopathy; Gene expression; In vitro; X ray irradiation; Mechanism; Signal transduction; Gamma irradiation; Ionizing irradiation; Enzymatic activity; Tumor necrosis factor; Tumor cell
• ISSN: 0008-5472; 1538-7445

Tumor necrosis factor (TNF) production following X-irradiation has been implicated in the biological response to ionizing radiation. Protein kinase C (PKC) is suggested to participate in TNF transcriptional induction and X-ray-mediated gene expression. We therefore studied radiation-mediated TNF expression in HL-60 cells with diminished PKC activity produced by either pretreatment with protein kinase inhibitors or prolonged 12-O-tetradecanoylphorbol-13-acetate treatment. Both treatments resulted in attenuation of radiation-mediated TNF induction. Consistent with these results, we found no detectable induction of TNF expression following X-irradiation in the HL-60 variant deficient in PKC-mediated signal transduction. The rapid activation of PKC following gamma-irradiation was established using an in vitro assay measuring phosphorylation of a PKC specific substrate. A 4.5-fold increase in PKC activity occurred 15 to 30 s following irradiation, which declined to baseline at 60 s. Two-dimensional gel electrophoresis of phosphoproteins extracted from irradiated cells demonstrated in vivo phosphorylation of the PKC specific substrate Mr 80,000 protein at 45 s following X-irradiation. These findings indicate that signal transduction via the PKC pathway is required for the induction of TNF gene expression by ionizing radiation.