2-Methoxyestradiol in the human corpus luteum throughout the luteal phase and its influence on lutein cell steroidogenesis and angiogenic activity

Abstract

To quantitate 2-methoxyestradiol (2-ME) in human corpus luteum (CL) of different ages and to determine the expression of cytochrome-P450-1A1 (CYP1A1) and catechol-O-methyl transferase (COMT) in CL and the action of 2-ME on P, vascular endothelial growth factor (VEGF) secretion, and luteal angiogenesis. Experimental study. University division of reproductive endocrinology. Twenty-four women of reproductive age. CL was collected from 15 women during the minilaparotomy for tubal sterilization. Granulosa lutein cells were harvested 36 hours after hCG administration in patients undergoing IVF. Levels of 2-ME were determined by high-performance liquid chromatography in CL. CYP1A1 and COMT were assessed by immunohistochemistry and Western blot. P and VEGF were measured by radioimmunoassay and ELISA. The angiogenic potential was analyzed using EA.hy926 cells. Plasma levels of E₂ decreased in the late luteal phase in association with an increase in luteal tissue of 2-ME concentrations. Concomitantly, there was a significant reduction of angiogenic activity in late CL. There was no significant variation in CYP1A1 and COMT expression in all CL. In physiological doses, 2-ME inhibited basal VEGF by granulosa lutein cells and diminished the angiogenic activity in conditioned media but did not prevent P and VEGF production stimulated by hCG. These data suggest the participation of 2-ME in physiological luteolysis by reducing angiogenesis. However, 2-ME did not prevent in vitro hCG stimulation of P biosynthesis, providing a mechanism for CL rescue in the cycle of conception.