Abstract
Epoxyeicosatrienoic acids (EETs) and the cytochrome P450 epoxygenase CYP2J2 promote tumorogenesis in vivo and in vitro via direct stimulation of tumor cell growth and inhibition of tumor cell apoptosis. Herein, we describe a novel mechanism of inhibition of tumor cell apoptosis by EETs. In Tca-8113 cancer cells, the antileukemia drug arsenic trioxide (ATO) led to the generation of reactive oxygen species (ROS), impaired mitochondrial function, and induced apoptosis. 11,12-EET pretreatment increased expression of the antioxidant enzymes superoxide dismutase and catalase and inhibited ATO-induced apoptosis. 11,12-EET also prevented the ATO-induced activation of p38 mitogen-activated protein kinase, c-Jun NH2-terminal kinase, caspase-3, and caspase-9. Therefore, 11,12-EET-pretreatment attenuated the ROS generation, loss of mitochondrial function, and caspase activation observed after ATO treatment. Moreover, the CYP2J2-specific inhibitor compound 26 enhanced arsenic cytotoxicity to a clinically relevant concentration of ATO (1–2 μM). Both the thiol-containing antioxidant, N-acetyl-cysteine, and 11,12-EET reversed the synergistic effect of the two agents. Taken together, these data indicate that 11,12-EET inhibits apoptosis induced by ATO through a mechanism that involves induction of antioxidant proteins and attenuation of ROS-mediated mitochondrial dysfunction.
Footnotes
This work was supported by the China Natural Science Foundation Committee [Grants 30700377, 30770882, 30430320]; the 973 Project [Grant 2007 CB512004]; and the Intramural Research Program of the National Institutes of Health National Institute of Environmental Health Sciences [Grant Z01-ES025034].
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
doi:10.1124/jpet.111.180505.
↵ The online version of this article (available at http://jpet.aspetjournals.org) contains supplemental material.
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ABBREVIATIONS:
- EET
- epoxyeicosatrienoic acid
- ERK
- extracellular signal-regulated kinase
- ATO
- arsenic trioxide
- ROS
- reactive oxygen species
- DCFH-DA
- 2,7-dichlorodihydrofluorescein diacetate
- SOD
- superoxide dismutase
- SRB
- sulforhodamine B
- MAPK
- mitogen-activated protein kinase
- JNK
- c-Jun NH2-terminal kinase
- C26
- compound 26
- PI
- propidium iodide
- NAC
- N-acetyl-l-cysteine
- FITC
- fluorescein isothiocyanate
- siRNA
- small interfering RNA
- ΔΨm
- mitochondrial transmembrane potential
- SP600125
- anthra[1–9-cd]pyrazol-6(2H)-one
- PD98059
- 2′-amino-3′-methoxyflavone
- SB203580
- 4-[4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-1H-imidazol-5-yl]pyridine.
- Received February 11, 2011.
- Accepted August 11, 2011.
- U.S. Government work not protected by U.S. copyright
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