GnRH regulates trophoblast invasion via RUNX2-mediated MMP2/9 expression.

study hypothesisWe hypothesized that Runt-related transcription factor 2 (RUNX2), matrix metalloproteinase (MMP)2 and MMP9 are involved in basal and gonadotrophin-releasing hormone (GnRH)-induced human extravillous trophoblast (EVT) cell invasion. STUDY FINDING: Our finding indicates that GnRH-induced RUNX2 expression enhances the invasive capacity of EVT cells by modulating the expression of MMP2 and MMP9. WHAT IS KNOWN ALREADY: GnRH is expressed in first-trimester placenta and exerts pro-invasive effects on EVT cells in vitro. RUNX2 regulates MMP2 and MMP9 expression and is often associated with invasive phenotypes. STUDY DESIGN, SAMPLES/MATERIALS,

methodsFirst-trimester human placenta (n = 9) was obtained from women undergoing elective termination of pregnancy. The localization of RUNX2, MMP2 and MMP9 in first-trimester human placenta was examined by immunohistochemistry. Primary or immortalized (HTR-8/SVneo) EVT cells were treated alone or in combination with GnRH, GnRH antagonist Antide, MAPK kinase inhibitor PD98095, phosphatidylinositol 3-kinase inhibitor LY294002, MMP2/9 inhibitor or small interfering RNAs (siRNAs) targeting RUNX2, MMP2 and/or MMP9. Protein and mRNA levels were measured by western blot and RT-PCR, respectively. Cell invasiveness was evaluated by transwell Matrigel or collagen I invasion assays. MAIN RESULTS AND THE ROLE OF CHANCE: RUNX2, MMP2 and MMP9 were detected in the cell column regions of human first-trimester placental villi. GnRH treatment increased RUNX2 mRNA and protein levels in HTR-8/SVneo cells and primary EVTs, and these effects were attenuated by co-treatment with Antide, PD98095 or LY294002. Down-regulation of RUNX2 by siRNA reduced basal and GnRH-induced MMP2/9 expression and cell invasion. Moreover, pharmacological inhibition or siRNA-mediated knockdown of MMP2/9 reduced basal and GnRH-induced cell invasion. LIMITATIONS, REASONS FOR CAUTION: The lack of an in vivo model is the major limitation of our in vitro study. WIDER IMPLICATIONS OF THE

findingsOur findings provide important insight into the functions of the GnRH - GnRH receptor system in early implantation and placentation. LARGE SCALE DATA: Not applicable. STUDY FUNDING AND COMPETING INTERESTS: This research was supported by Canadian Institutes of Health Research (Grant #143317) to P.C.K.L. The authors have nothing to disclose.