Downregulation of HIF-2α Enhances Apoptosis and Limits Invasion in Human Placental JEG-3 Trophoblast Cells

Pre-eclampsia, one of the major disorders of pregnancy, is characterized by inadequate trophoblast invasion and defective trophoblast-mediated remodeling of placental vasculature. Hypoxia-inducible transcription factor (HIF)-2 alpha plays a critical role in regulating cellular function of trophoblasts; however, its role in placental development and in the pathogenesis of pre-eclampsia remains elusive. CCK-8 assay was used to detect cell viability. Invasion assay was performed to determine the effect of HIF-2 alpha on trophoblast function. Flow cytometry was used for detecting apoptosis and cell cycle. The mRNA and protein expressions of HIF-2 alpha, VEGF, iNOS, and ET-1 were determined by quantitative real-time PCR and western blot techniques. The roles of HIF-2 alpha in JEG-3 trophoblast cells were examined using siRNA technology. The presence of HIF-2 alpha siRNA reduced the levels of cell viability after 48 h incubation, and the cell viability further reduced at 72 h. Besides, HIF-2 alpha siRNA enhanced trophoblast apoptosis, as determined by flow cytometric measurement. Increased G1-phase and decreased S-phase cell population were induced by HIF-2 alpha siRNA based on the determination of cell cycle distribution using propidium iodide staining. Furthermore, the invasive ability of JEG-3 trophoblasts was significantly reduced by HIF-2 alpha siRNA. In addition, knockdown of the HIF-2 alpha gene significantly decreased VEGF, iNOS, and ET-1 levels in JEG-3 human trophoblasts. Our findings provide preliminary evidence of the functions of HIF-2 alpha in trophoblast biology and suggest that the downregulation of HIF-2 alpha enhances cell apoptosis and limits trophoblast invasion.