2-Methoxyestradiol regulates VEGFR-2 and sFlt-1 expression in human placenta

Abstract

Introduction 2-Methoxyestradiol (2-ME), a metabolite of estradiol, has been identified as an initiator of cytotrophoblast transformation to an invasive phenotype, with low levels implicated with the onset of preeclampsia. Here, we investigated the effects of 2-ME on VEGFR-2, sFlt-1 and HIF1α expression in human placenta. Methods First trimester human placental villous explants were maintained at 3% and 20% O2. Samples were treated with 0.5 μM 2-ME with or without 1 mM DMOG or 0.2 mM CoCl2 for 17 h. Western and qPCR analyses were performed for VEGFR-2, sFlt-1 and HIF1α expression levels. sFlt-1 specific ELISA was also performed on conditioned explant media. Results Placental explants maintained at 3% O2 revealed decreased protein and transcript levels of VEGFR-2 with increased sFlt-1 and HIF1α. Overnight treatment with 0.5 μM 2-ME rescued altered expression levels of VEGFR-2, sFlt-1 and HIF1α. 2-ME also decreased levels of sFlt-1 in conditioned explant media. While 2-ME treatment rescued decreased levels of VEGFR-2 in DMOG and CoCl2-treated explants, no effect was observed for sFlt-1 levels. Furthermore, 2-ME was observed to further exacerbate elevated HIF1α levels by DMOG and CoCl2. Discussion 2-ME rescues altered levels of VEGFR-2, sFlt-1 and HIF1α in hypoxic placental explants, suggesting potential therapeutic measures for the treatment of preeclampsia. However, the unaltered sFlt-1 levels and enhanced HIF1α levels by 2-ME in DMOG and CoCl2 treated explants suggests 2-ME also elicits its effects through HIF1α-independent pathways.