Inhibitors of Cytochrome P450 4A Inhibit Angiogenic Responses to VEGF

Abstract

Abstract: : Cytochrome P450 enzymes of the 4A family (CYP4A) convert arachidonic acid to 20–hydroxyeicosatetraenoic acid (20–HETE) in blood vessels of several vascular beds. . Little is known about the role of CYP4A and thus 20–HETE in regulation of angiogenesis. Vascular Endothelial Growth Factor (VEGF) is a fundamental regulator of angiogenesis. Purpose: to determine if inhibition of CYP4A affects angiogenic responses to VEGF. Methods: The present study examined the effects of inhibiting the formation of 20–HETE with N–hydroxy–N’–(4–butyl–2–methylphenol) formamidine (HET0016) on the mitogenic response of vascular endothelial growth factor (VEGF) in human umbilical vein endothelial cells (HUVECs) in vitro and on VEGF–induced angiogenesis in the cornea of rats in vivo. Results: HET0016 (10 µM and 20 µg, respectively) abolished the mitogenic response to VEGF in HUVECs and the angiogenic response to VEGF, by 80%–90% (p < 0.001). Dibromododecenyl methylsulfonimide (DDMS), a structurally and mechanistically different inhibitor of 20–HETE synthesis, also abolished angiogenic responses when tested with VEGF. Additionally, administration of the stable 20–HETE agonist 20–hydroxyeicosa–6(Z), 15(Z)–dienoic acid (WIT003) induced mitogenesis in HUVECs and angiogenesis in the rat cornea in vivo. We studied the ability of HET0016 to alter the angiogenic response in the rat cornea to human glioblastoma cancer cells (U251). When administered locally into the cornea, HET0016 (20 µg) reduced the angiogenic response to U251 cancer cells by 70%. Conclusions: These results suggest that a CYP4A product, possibly 20–HETE, plays a critical role in the regulation of angiogenesis. Inhibition of CYP4A may be useful for reduction of pathological angiogenesis.

Keywords: neovascularization • growth factors/growth factor receptors • eicosanoids