Epoxyeicosatrienoic acids (EETs) are small molecules produced by cytochrome P450 epoxygenases. They are lipid mediators that act as autocrine or paracrine factors to regulate inflammation and vascular tone. As a result, drugs that raise EET levels are in clinical trials for the treatment of hypertension and many other diseases. However, despite their pleiotropic effects on cells, little is known about the role of these epoxyeicosanoids in cancer. Here, using genetic and pharmacological manipulation of endogenous EET levels, we demonstrate that EETs are critical for primary tumor growth and metastasis in a variety of mouse models of cancer. Remarkably, we found that EETs stimulated extensive multiorgan metastasis and escape from tumor dormancy in several tumor models. This systemic metastasis was not caused by excessive primary tumor growth but depended on endothelium-derived EETs at the site of metastasis. Administration of synthetic EETs recapitulated these results, while EET antagonists suppressed tumor growth and metastasis, demonstrating in vivo that pharmacological modulation of EETs can affect cancer growth. Furthermore, inhibitors of soluble epoxide hydrolase (sEH), the enzyme that metabolizes EETs, elevated endogenous EET levels and promoted primary tumor growth and metastasis. Thus, our data indicate a central role for EETs in tumorigenesis, offering a mechanistic link between lipid signaling and cancer and emphasizing the critical importance of considering possible effects of EET-modulating drugs on cancer.

Cytochrome P450 (CYP) epoxygenases convert arachidonic acid to four regioisomeric epoxyeicosatrienoic acids (EET), which exert diverse biological activities in a variety of systems. We previously reported that the CYP2J2 epoxygenase is overexpressed in human cancer tissues and cancer cell lines and that EETs enhance tumor growth, increase carcinoma cell proliferation, and prevent apoptosis of cancer cells. Herein, we report that CYP epoxygenase overexpression or EET treatment promotes tumor metastasis independent of effects on tumor growth. In four different human cancer cell lines in vitro, overexpression of CYP2J2 or CYP102 F87V with an associated increase in EET production or addition of synthetic EETs significantly induced Transwell migration (4.5-to 5.5-fold), invasion of cells (3-to 3.5-fold), cell adhesion to fibronectin, and colony formation in soft agar. In contrast, the epoxygenase inhibitor 17-ODYA or infection with the antisense recombinant adeno-associated viral vector (rAAV)-CYP2J2 vector inhibited cell migration, invasion, and adhesion with an associated reduction in EET production. CYP overexpression also enhanced metastatic potential in vivo in that rAAV-CYP2J2-infected MDA-MB-231 human breast carcinoma cells showed 60% more lung metastases in athymic BALB/c mice and enhanced angiogenesis in and around primary tumors compared with control cells. Lung metastasis was abolished by infection with the antisense rAAV-CYP2J2 vector. CYP epoxygenase overexpression or EET treatment up-regulated the prometastatic matrix metalloproteinases and CD44 and down-regulated the antimetastatic genes CD82 and nm-23. Together, these data suggest that CYP epoxygenase inhibition may represent a novel approach to prevent metastasis of human cancers. [Cancer Res 2007;67(14):6665-74]

Renal cytochrome P450 (CYP)-derived epoxyeicosatrienoic acids (EETs) regulate sodium transport and blood pressure. Although endothelial CYP-derived EETs are potent vasodilators, their contribution to the regulation of blood pressure remains unclear. Consequently, we developed transgenic mice with endothelial expression of the human CYP2J2 and CYP2C8 epoxygenases to increase endothelial EET biosynthesis. Compared to wild-type littermate controls, an attenuated afferent arteriole constrictor response to endothelin-1 and enhanced dilator response to acetylcholine was observed in CYP2J2 and CYP2C8 transgenic mice. CYP2J2 and CYP2C8 transgenic mice demonstrated modestly, but not significantly, lower mean arterial pressure under basal conditions compared to wild-type controls. However, mean arterial pressure was significantly lower in both CYP2J2 and CYP2C8 transgenic mice during coadministration of N-nitro-l-arginine methyl ester and indomethacin. In a separate experiment, a high-salt diet and subcutaneous angiotensin II was administered over 4 wk. The angiotensin/high-salt-induced increase in systolic blood pressure, proteinuria, and glomerular injury was significantly attenuated in CYP2J2 and CYP2C8 transgenic mice compared to wild-type controls. Collectively, these data demonstrate that increased endothelial CYP epoxygenase expression attenuates afferent arteriolar constrictor reactivity and hypertension-induced increases in blood pressure and renal injury in mice. We conclude that endothelial CYP epoxygenase function contributes to the regulation of blood pressure.

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