Osteopontin facilitates invasion in human trophoblastic cells via promoting matrix metalloproteinase-9 in vitro

Successful implantation of embryo and placentation depend on proper trophoblast proliferation and differentiated into specialized invasive trophoblast. However, little is known about the regulatory factors and mechanisms in trophoblast proliferation and differentiation. Osteopontin (OPN) is a member of the small integrin-binding ligand N-linked glycoprotein family and participates in cell adhesion and invasion. It has been identified that OPN is highly expressed in invasive trophoblasts in human placenta. In this study, we demonstrated that OPN is constitutively expressed in highly invasive phenotype of human choriocarcinoma cell lines of JAR and JEG-3 cells, and OPN could promote trophoblast proliferation and invasion, partly through promoting MMP-9 secretion. Inhibition of OPN will compromise the abilities of proliferation and invasion in JAR and JEG-3 cell lines. Our data showed that the expression of OPN in trophoblast may participate in placentation, OPN expression defects may be involved in gestational trophoblastic diseases.