Downregulation of LncRNA-MEG3 promotes HTR8/SVneo cells apoptosis and attenuates its migration by repressing Notch1 signal in preeclampsia

A successful pregnancy crucially depends on well-regulated extravillous trophoblast migration and invasion. Maternally expressed gene 3 (MEG3) is a long noncoding RNA that plays an important role in regulating trophoblast cells cell function. As previously reported, the expression of MEG3 was reduced in preeclampsia, and downregulation of MEG3 could suppress trophoblast cells migration and promote its apoptosis. However, the downstream regulatory mechanism of MEG3 remains unknown. As reported, MEG3 could inhibit cell proliferation in endometrial carcinoma by regulating Notch signaling. Our previous studies have demonstrated that Notch1 is downregulated in preeclampsia and that inhibiting the expression of Notch1 could promote trophoblast cell apoptosis. Therefore, this study was designed to investigate the role of MEG3 and its the relationship with Notch1 in trophoblasts. In this study, the mRNA expression levels of both MEG3 and Notch1 were decreased in preeclampsia placenta (n=15) compared to the normal samples (n=15). Exogenous upregulation and downregulation of MEG3 in HTR8/SVneo cells were performed to investigate the role of MEG3 in cell biological behavior and its effects on Notch1 expression. The results showed that MEG3 enhancement promoted trophoblast cell migration and invasion and inhibited cell apoptosis. Downregulation of MEG3 elicited the opposite results. Associated factors, such as matrix metalloproteinases 2 (MMP2), BAX, and Bcl-2, were examined at the mRNA and protein levels. Our study demonstrated that MEG3 could regulate Notch1 expression to modulate trophoblast cell migration, invasion, and apoptosis, which may represent the molecular mechanism of poor placentation during preeclampsia.