RBP4 regulates trophoblastic cell proliferation and invasion via the PI3K/AKT signaling pathway

Insufficient trophoblast invasion is associated with preeclampsia (PE) development. Retinol-binding protein 4 (RBP4) is important for regulating cell differentiation, migration and invasion. The aim of the present study was to determine RBP4 expression and function in the human placenta and to examine the underlying mechanisms. In the present study, RBP4 expression was determined in serum samples from 35 pregnant women with PE and 30 healthy pregnant women using enzyme-linked immunosorbent assays. Cell proliferation was assessed by Cell Counting Kit-8 assays, and cell invasion was examined with transwell assays. RBP4 concentrations were significantly lower in the PE group when compared with the control group. RBP4 overexpression enhanced HTR8/SVneo cell proliferation and invasion, and the levels of phosphorylated (p-) phosphoinositide 3-kinase (PI3K) and p-protein kinase B (AKT) in HTR8/SVneo cells. RBP4 knockdown significantly inhibited HTR8/SVneo cell proliferation and invasion, and repressed the expression of matrix metalloproteinases. In addition, RBP4 knockdown significantly reduced the levels of p-PI3K and p-AKT in HTR8/SVneo cells. Taken together, the results of the present study demonstrated that RBP4 overexpression increased HTR8/SVneo cell proliferation and invasion by suppressing PI3K/AKT signaling and RBP4 knockdown induced the opposite effects.