Gonadotropin-releasing hormone regulates human trophoblastic cell invasion via TWIST-induced N-cadherin expression.

Abstract

GnRH and its receptor, GnRHR, were shown to promote trophoblastic cell invasion. Detection of elevated early development-related transcription factor TWIST and adhesion molecule N-cadherin in the invasive trophoblastic cells could suggest that GnRH promotes trophoblastic cell invasion through TWIST-regulated N-cadherin pathway. This study sought to investigate the regulatory effect of GnRH on TWIST and N-cadherin expression as well as invasiveness in human trophoblastic cells. The expression of GnRHR, TWIST, and N-cadherin was first examined in human first-trimester chorionic villi by immunohistochemistry. Expression levels of GnRHR, TWIST, and N-cadherin were tested in primary extravillous trophoblastic (EVT) cells and an immortalized EVT cell line HTR-8/SVneo cells with incubation of GnRH and its antagonist, Antide. Small interfering RNA strategy was used to study the roles of TWIST and N-cadherin in basal- and GnRH-regulated trophoblast invasion. Matrigel-mediated transwell invasion assays were employed to assess cell invasion capacity. GnRHR, TWIST, and N-cadherin were detected at the invasive site of first-trimester human placenta. GnRH treatment significantly increased TWIST and N-cadherin expression in primary EVT as well as HTR-8/SVneo cells. Pretreatment with the GnRH receptor antagonist Antide attenuated the effects of GnRH on TWIST and N-cadherin expression. Invasive capacity of primary EVT and HTR-8/SVneo cell was reduced following siRNA-mediated knockdown of either TWIST or N-cadherin. Furthermore, by knocking down endogenous TWIST, the expression level of N-cadherin was reduced as well as GnRH-induced HTR-8/SVneo cell invasion. Treatment with GnRH induces AKT phosphorylation and Phosphoinositide3-kinase inhibitor LY294002 attenuates the effects of GnRH on TWIST and N-cadherin expression and trophoblastic cell invasion. Our results suggest that GnRH acts via its receptor to induce AKT phosphorylation, which contributes to elevated TWIST expression. Increased levels of TWIST subsequently induce N-cadherin expression, which promotes human trophoblastic cell invasion in vitro.