Cytochrome P450 (CYP) 2C epoxygenases metabolize arachidonic acid to epoxyeicosatrienoic acids (EETs), intracellular signaling molecules inducing endothelial cell proliferation and angiogenesis. As the expression of CYP2C, like that of the vascular endothelial growth factor (VEGF) is enhanced by hypoxia we determined in endothelial cells whether EETs act as second messengers in the VEGF-induced angiogenesis. VEGF increased CYP 2C promoter activity, mRNA and protein expression as well as EET levels in endothelial cells. Moreover, CYP2C9 overexpression enhanced VEGF receptor 2 mRNA and protein levels, effects sensitive to the CYP 2C9 inhibitor sulfaphenazole and the EET antagonist 14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EEZE). Functional evidence for a role of EETs in VEGF-induced angiogenesis was obtained in a fibrin gel assay in which 14,15-EEZE reduced VEGF-induced tube formation by approximately 30%, without affecting tube formation induced by basic fibroblast growth factor (bFGF). VEGF-induced angiogenesis in mice in vivo (Matrigel plug assay) was also abolished by 14,15-EEZE while the response to bFGF was not affected.

Taken together, these data indicate, that CYP 2C-derived EETs act as second messengers in the VEGF-induced angiogenesis.