Increased miRNA-518b inhibits trophoblast migration and angiogenesis by targeting EGR1 in early embryonic arrest

Evidence indicates that microRNAs (miRNAs) play essential roles in early embryonic development. The miRNA-518 family is a special biomarker of the placenta, and miRNA-518b is abnormally expressed in placental tissue in preeclampsia. Early growth response protein 1 (EGR1), a zinc finger transcriptional factor, plays an essential role in regulating cell differentiation, angiogenesis, and migration. Moreover, earlier studies have shown that EGR1 protein plays a key role in implantation. However, little is known about the role of miR-518b and EGR1 on early embryonic arrest (EEA) in humans. In our study, increased miR-518b along with decreased EGR1 was found in human villus tissues with EEA. Furthermore, we demonstrated by luciferase assay that miR-518b is a direct regulator of EGR1. After comparing the effect of silencing EGR1, vascular endothelial growth factor (VEGF) individually, and EGR1/VEGF in combination, we found that EGR1 can inhibit migration and angiogenesis of HTR-8 SVneo cells by decreasing the VEGF expression. Hypoxia plays an initial role in early embryonic development, and we found that hypoxia reduces the expression of miR-518b and increases the expression of EGR1 and VEGF to facilitate migration and angiogenesis in a hypoxic model of HTR-8/SVneo cell line. Our findings provide new insights into the role of miR-518b in EEA and implicate the potential application of miR-518b in the diagnosis and development of intervention for EEA.