Hyperthermia and tumour necrosis factor-alpha induced apoptosis via mitochondrial damage.
Hyperthermia is a potential anti-cancer regimen but the mode of action is far from clear. Based on the flow cytometric analysis with FITC-annexin V and propidium iodide, apoptosis was found to be the major form of cell death after the treatment with hyperthermia (43 degrees C, 3 h) and/or recombinant murine tumour necrosis factor-alpha (TNF-alpha, 50 ng/ml) in L929 cells. Since mitochondria are thought to play a key role in apoptosis, experiments were done to assess their role in the hyperthermia-mediated apoptosis. Our results indicate that hyperthermia was able to depolarize the mitochondrial membrane potential (delta psi m) and release cytochrome c to the cytoplasm, in a way very similar to the action of TNF-alpha. With the use of cyclosporin A to inhibit the delta psi m dissipation, the cytotoxicity mediated by hyperthermia or TNF-alpha was suppressed. Taken together, our results indicate that hyperthermia and TNF-alpha can induce apoptosis in L929 cells and the mitochondrial dysfunction plays a key role in the cell death process.
Yuen
W F
WF
Department of Biochemistry, The Chinese University of Hong Kong, Shatin, Hong Kong, People's Republic of China.
Fung
K P
KP
Lee
C Y
CY
Choy
Y M
YM
Kong
S K
SK
Ko
S
S
Kwok
T T
TT
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002460:Cell Line; D016572:Cyclosporine / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D005334:Fever / Q000473:pathology*; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D007166:Immunosuppressive Agents / Q000494:pharmacology; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008928:Mitochondria / Q000187:drug effects* / Q000648:ultrastructure; D013778:Tetrazolium Salts; D013844:Thiazoles; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000633:toxicity*
D003574:Cytochrome c Group; D005456:Fluorescent Dyes; D007166:Immunosuppressive Agents; D013778:Tetrazolium Salts; D013844:Thiazoles; D014409:Tumor Necrosis Factor-alpha; D016572:Cyclosporine; C022616:thiazolyl blue; D016650:Fluorescein-5-isothiocyanate