MicroRNA-135b-5p regulates trophoblast cell function by targeting phosphoinositide-3-kinase regulatory subunit 2 in preeclampsia

The level of miR‑135b-5p is lower in patients with preeclampsia (PE) superimposed on chronic hypertension than in healthy controls. However, the function of miR‑135b-5p in PE progression remains unknown. In the present study, we investigated the role of miR‑135b-5p in PE development and its possible mechanism for the first time. HTR8/SVneo cells (trophoblast cell line) were exposed to hypoxia/reoxygenation (H/R) to mimic PE in vitro. Hypoxia-inducible factor-1α (HIF-1α), forkhead box O3A (FOXO3a), and miR-135b-5p levels were measured using Real-time PCR. Cell proliferation, apoptosis and migration/invasion were evaluated using the Cell Counting Kit-8 (CCK-8), flow cytometry and transwell assays, respectively. Real-time PCR and Western blotting were performed to determine the levels of several pro- and anti-angiogenic factors. The binding of miR-135b-5p to the PIK3R2-3’ untranslated region (3ʹUTR) was confirmed by bioinformatics analysis and a dual-luciferase reporter assay. H/R exposure greatly upregulated HIF-1α, FOXO3a, and PIK3R2 levels, while downregulating miR-135b-5p levels in HTR8/SVneo cells. H/R exposure resulted in the inhibition of proliferation, migration, invasion, angiogenesis, and the induction of apoptosis. MiR-135b-5p overexpression reversed the effects of H/R on trophoblast cell function, while miR-135b-5p knockdown enhanced the effects. PIK3R2 knockdown had similar effects as miR-135b-5p overexpression on proliferation, apoptosis and angiogenesis. The effect of miR-135b-5p overexpression on H/R-exposed cells was enhanced by PIK3R2 knockdown. MiR-135b-5p downregulated PIK3R2 expression by pairing with its 3ʹUTR. Therefore, miR-135b-5p may regulate trophoblast function by targeting PIK3R2 in PE and could serve as a novel therapeutic target for PE.