BCAM Deficiency May Contribute to Preeclampsia by Suppressing the PIK3R6/p-STAT3 Signaling.

Background: Preeclampsia is a pregnancy syndrome that may utilize multiple pathogenic mechanisms. Insufficient trophoblast invasion and impaired uterine spiral artery remodeling are believed to be the pathological basis; yet the underlying mechanisms remain largely unclear.

Methods: The placental BCAM (basal cell adhesion molecule) expression and important clinical indicators were detected and correlation analysis was performed. MiRNAs directly targeting BCAM were predicted and further verified by dual-luciferase reporter gene, and the downstream molecular mechanisms of BCAM were investigated in both HTR-8/SVneo and JAR cells. In addition, pregnant/nonpregnant rats were treated with adenoviruses containing BCAM shRNA genes (Ad-shBCAM) on gestational 9.5 days to detect the preeclamptic features.

Results: The BCAM is highly expressed on the trophoblast membrane and decreased in the preeclamptic placentae. In HTR-8/SVneo and JAR cells, BCAM knockdown inhibited trophoblast proliferation, migration, and invasion, and suppressed phosphorylation on Y705 of STAT3 dependent on the downregulation of PIK3R6. Moreover, miR-199a-5p mediated the degradation of BCAM and also inhibited trophoblast proliferation, migration, and invasion. In vivo, BCAM deficiency induced a preeclampsia-like phenotype included elevated systolic blood pressure, proteinuria, impaired morphology and function of multiple organs (placenta, liver, and kidney), and fetal growth restriction. The expression of placenta BCAM/PIK3R6/p-STAT3 signaling was also downregulated in this preeclampsia rat model.

Conclusions: MiR-199a-5p mediated-BCAM deficiency contributes to the suppression of trophoblast proliferation, migration, and invasion by inhibiting PIK3R6/p-STAT3 signaling, which may lead to poor placentation and result in preeclampsia-like phenotypes. Our study provides a new academic perspective on the pathogenesis of preeclampsia.