Estradiol-17β and Its Cytochrome P450-and Catechol-O-Methyltransferase-Derived Metabolites Stimulate Proliferation in Uterine Artery Endothelial Cells Role of Estrogen Receptor-α Versus Estrogen Receptor-β

Estradiol-17 beta (E-2 beta) and its metabolites, which are sequentially synthesized by cytochrome P450s and catechol-O-methyltransferase to form 2 and 4-hydroxyestradiol (OHE2) and 2- and 4-methoxestradiol (ME2), are elevated during pregnancy. We investigated whether cytochrome P450s and catechol-O-methyltransferase are expressed in uterine artery endothelial cells (UAECs) and whether E-2 beta and its metabolites modulate cell proliferation via ER-alpha and/or ER-beta and play roles in physiological uterine angiogenesis during pregnancy. Cultured ovine UAECs from pregnant and nonpregnant ewes were treated with 0.1 to 100.0 nmol/L of E-2 beta, 2-OHE2, 4-OHE2, 2-ME2, and 4-ME2. ER-beta or ER-beta specificity was tested using ICI 182 780, ER-alpha-specific 1,3-bis(4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinyleth oxy)phenol]-1H-pyrazole dihydrochloride, ER-beta-specific 4-[2-phenyl-5,7-bis(trifluoromethyl) pyrazolo [1,5-a]pyrimidin-3-yl]phenol antagonists and their respective agonists ER-alpha-specific 4,4',4 ''-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol and ER-beta-specific 2,3-bis(4-Hydroxyphenyl)-propionitrile. Angiogenesis was evaluated using 5-bromodeoxyuridine proliferation assay. Using confocal microscopy and Western analyses to determine enzyme location and levels, we observed CYP1A1, CYP1A2, CYP1B1, CYP3A4, and catechol-O-methyltransferase expression in UAECs; however, expressions were similar between nonpregnant UAECs and pregnant UAECs. E-2 beta, 2-OHE2, 4-OHE2, and 4-ME2 treatments concentration-dependently stimulated proliferation in pregnant UAECs but not in nonpregnant UAECs; 2-M-2 did not stimulate proliferation in either cell type. Proliferative responses of pregnant UAECs to E-2 beta were solely mediated by ER-beta, whereas responses to E-2 beta metabolites were neither ER-alpha nor ER-beta mediated. We demonstrate an important vascular role for E-2 beta, its cytochrome P450- and catechol-O-methyltransferase-derived metabolites, and ER-beta in uterine angiogenesis regulation during pregnancy that may be dysfunctional in preeclampsia and other cardiovascular disorders. (Hypertension. 2010;55:1005-1011.)