AQP9 causes recurrent spontaneous abortion by inhibiting trophoblast cell EMT and invasion through the PI3K/AKT pathway

Background: Invasion of the endometrium by trophoblast cells is a key event during pregnancy, although the underlying mechanism remains unclear. AQP9 is expressed in many eukaryotes and is associated with cell invasion. The objective of this study was to evaluate the significance of Aquaporin 9(AQP9) in recurrent spontaneous abortion (RSA).

Methods: We screened the GSE22490 dataset and further differentiated AQP9 expression in villi. AQP9 was evaluated as one of the key factors in abortion by injecting AQP9 overexpressed plasmid into the uterus of CD1 mice. Trophoblast cells were transfected with AQP9-overexpressing plasmid or siAQP9 to measure cell proliferation, migration, invasion, and Apoptosis. Western blot was used to measure changes in the expression of invasion, epithelial-mesenchymal transformation (EMT) process, and PI3K/Akt pathway. Finally, the role of AQP9 in PI3K/Akt signaling pathway was determined using the PI3K/Akt Inhibitor, LY294002, and activator, 740Y-P.

Results: AQP9 is highly expressed in RSA villus. Intrauterine injections of AQP9-overexpressing plasmid into CD1 mice resulted in atrophy and blackness of the gestational sac and increased the rate of absorption, it is the causative factor of abortion. AQP9 upregulation inhibited the proliferation, invasion, migration, and EMT process in vitro of trophoblast cells and increased cell Apoptosis. The opposite result was observed after silencing AQP9. AQP9 overexpression also inhibited the PI3K/Akt pathway. LY294002 and 740Y-P partially recovered AQP9-induced trophoblast invasion and migration via the PI3K/Akt pathway.

Conclusions: AQP9 reduces the invasive ability of trophoblast cells by regulating PI3K/Akt signaling pathway, participating in RSA.

AQP9; PI3K/AKT pathway; invasion; recurrent spontaneous abortion; trophoblast cell.