Abstract
Epoxyeicosatrienoic acid(s) (EET) have variable hemodynamic, anti-inflammatory, and growth regulatory effects, and inhibitors of their regulatory enzyme, soluble epoxide hydrolase (sEH), can mimic these effects. For this reason, sEH inhibitors are being studied as potential pharmaceuticals for the treatment of hypertension, atherosclerosis, and inflammatory diseases. We now show that a highly selective urea-based sEH inhibitor 1-cyclohexyl-3-dodecyl urea (CDU) attenuates human aortic vascular smooth muscle (HVSM) cell proliferation independently of any effect on sEH. CDU also inhibits endothelial cells when stimulated with basic fibroblast growth factor or serum. In addition, we demonstrate that EET, as well as several newer generation sEH inhibitors and a urea-based weak sEH inhibitor, do not affect proliferation in HVSM cells. Structure-activity relationships demonstrate that the addition of an acid group to the dodecyl carbon chain, changing the cyclohexyl group to an adamantyl group, and shortening the carbon chain to two carbons all abolish the antiproliferative effect. Our finding that a highly selective urea-based inhibitor of sEH can alter biology independently of its putative target enzyme suggests that there may be other useful properties of this class of compounds unrelated to their influence on epoxyeicosanoids. In addition, our results show that caution should be used when attempting to infer conclusions of EET biology based solely on the effects these inhibitors in tissue culture models, especially when used at micromolar concentrations.
Footnotes
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This work was supported by Grant 1R21CA 91259-01A1 from the National Cancer Institute, National Institutes of Health (to R.H.W. and B.B.D.), and grants from the Philip Morris External Research Program, the American Heart Association, the Research Service of the United States Department of Veterans Affairs, and Dialysis Clinics, Inc.
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B.D.H. and C.M. are supported by National Institutes of Health, National Institute of Environmental Health Sciences (NIEHS) Grant R01 ES02710, NIEHS Superfund Basic Research Program Grant P42 ES04699, NIEHS Center for Children's Environmental Health & Disease Prevention Grant 1 P01 ES11269, and NIEHS Center Grant P30 ES05707.
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doi:10.1124/jpet.105.091876.
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ABBREVIATIONS: EET, epoxyeicosatrienoic acid(s); sEH, soluble epoxide hydrolase; CDU, 1-cyclohexyl-3-dodecyl urea; FGF, fibroblast growth factor; bFGF, basic FGF; PDGF, platelet-derived growth factor; DHET, dihydroxyeicosatrienoic acids; LC, liquid chromatography; MS, mass spectrometry; VSM, vascular smooth muscle; HVSM, human vascular smooth muscle; DMSO, dimethyl sulfoxide; tDPPO, [3H]trans-1,3-diphenylpropene oxide; ADU, 1-adamantyl-3-dodecyl urea; CUDA, 12-(3-cyclohexylureido)-dodecanoic acid; AUDA-BE, 12-(3-adamantylureido)-dodecanoic acid butyl ester; 950, 1-adamantyl-3-(5-(2-(2-ethoxyethoxy)ethoxy)pentyl urea; CEU, cyclohexyl ethyl urea; EC, endothelial cells; HPLC, high-pressure liquid chromatography; PPARα, peroxisome proliferator-activated receptor.
- Received July 1, 2005.
- Accepted October 11, 2005.
- The American Society for Pharmacology and Experimental Therapeutics
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