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Enhancement of apoptosis by nitric oxide released from α‐phenyl‐ tert ‐butyl nitrone under hyperthermic conditions
Author(s) -
Cui ZhengGuo,
Kondo Takashi,
Matsumoto Hideki
Publication year - 2006
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.20482
Subject(s) - apoptosis , nitric oxide , peroxynitrite , cytochrome c , chemistry , superoxide , hyperthermia , intracellular , biochemistry , microbiology and biotechnology , biology , medicine , organic chemistry , enzyme
The aim of this study was to examine whether a neuroprotector, PBN (α‐phenyl‐ tert ‐butyl nitrone), enhances apoptosis induced by hyperthermia, which generates superoxide (O 2 − ) intracellularly, since the release of nitric oxide (NO) from PBN under oxidative stress has been reported. When human myelomonocytic lymphoma U937 cells were treated with hyperthermia (44°C, 10 min) and PBN, an increase in the concentration of nitrite in the culture medium, and a decrease in the hyperthermia‐induced production of O 2 −was observed. Imaging using a fluorescence dye for intracellular NO, diaminofluorescein‐2 diacetate (DAF‐2 DA), revealed the formation of NO in the apoptotic cells treated with hyperthermia and PBN combined. Apoptotic endpoints were significantly enhanced by the combined treatment: a decrease in mitochondrial trans‐membrane potential, cleavage of Bid, release of cytochrome c, and activation of caspase‐8 and ‐3. An increase in the intracellular Ca 2+ concentration ([Ca 2+ ] i ), externalization of Fas, and decrease in Hsp70 and phosphorylated HSF1 were observed following the combined treatment. Furthermore, scavengers of NO and ONOO − significantly inhibited the enhancement of apoptosis, the externalization of Fas and the increase in [Ca 2+ ] i . These results suggest that, (1) NO is released from PBN by hyperthermia, and subsequently reacts with O 2 −to form ONOO − , (2) NO and ONOO − are involved in the enhancement of apoptosis through Fas‐mitochondria‐caspase and [Ca 2+ ] i ‐dependent pathways, and (3) a decrease in Hsp70 and phosphorylated HSF1 also contributed to the enhancement of apoptosis. J. Cell. Physiol. 206: 468–476, 2006. © 2005 Wiley‐Liss, Inc.