Febrile and acute hyperthermia enhance TNF-induced necrosis of murine L929 fibrosarcoma cells via caspase-regulated production of reactive oxygen intermediates.
Previous studies have demonstrated the essential role of TNF-induced reactive oxygen intermediates (ROI) in the necrosis of L929 cells. We investigated the molecular basis for the interaction of hyperthermia and TNF in these cells. Hyperthermia, both febrile (40.0-40.5 degrees C) and acute (41.5-41.8 degrees C), strongly potentiated TNF killing, and sensistization was significantly quenched by the antioxidant, BHA. The broad-spectrum caspase inhibitor, Z-VAD, has been shown to markedly increase the TNF sensitivity of L929 cells at 37 degrees C; we observed that hyperthermia would also enhance the sensitivity of L929 cells to TNF + Z- VAD and that BHA could significantly quench the response, as well. The basis for hyperthermic potentiation was unlikely thermally-increased sensitivity to ROI, as treatment with hydrogen peroxide for 24 h killed L929 cells essentially equivalently, whether incubated continuously at 37 degrees C or at 40.0-40.5 degrees C, or for 2 h at 41.5-41.8 degrees C. However, febrile and acute hyperthermia markedly increased TNF-induced production of ROI, with or without Z-VAD. Hyperthermia dramatically accelerated the onset of this production, as well as the onset of necrotic death, as determined by oxidation of dihydro-rhodamine and propidium iodide staining, respectively, both of which were significantly quenchable with BHA. We conclude that hyperthermia potentiates TNF-mediated killing in this cell model primarily by increasing the afferent, and not the efferent, phase of TNF-induced necrosis.
Department of Molecular & Cellular Oncology, The University of Texas, MD Anderson Cancer Center, Houston, Texas, USA.
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Klostergaard
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D002083:Butylated Hydroxyanisole / Q000494:pharmacology; D020169:Caspases / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004317:Doxorubicin / Q000494:pharmacology; D005334:Fever / Q000378:metabolism* / Q000473:pathology*; D005354:Fibrosarcoma; D009336:Necrosis; D011506:Proteins / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000201:enzymology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D000590:Amino Acid Chloromethyl Ketones; D000970:Antineoplastic Agents; D000975:Antioxidants; D015853:Cysteine Proteinase Inhibitors; D011506:Proteins; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D002083:Butylated Hydroxyanisole; D004317:Doxorubicin; D020169:Caspases