HGF regulate HTR-8/SVneo trophoblastic cells migration/invasion under hypoxic conditions through increased HIF-1α expression via MAPK and PI3K pathways.

Hepatocyte growth factor (HGF) is reported to be down-regulated in pregnancy complications like intrauterine growth retardation and preeclampsia, which are associated with abnormal trophoblast migration/invasion. In this study, role of HGF and associated signaling pathways has been investigated in HTR-8/SVneo trophoblastic cells migration/invasion under normoxia (20% O2) and hypoxia (2% O2). HTR-8/SVneo cells exposed to hypoxia showed increase in migration and invasion as compared to cells incubated under normoxic conditions. The migration/invasion under both normoxic and hypoxic conditions was further enhanced after treatment with HGF. Subsequent to treatment with HGF, a significant increase in expression of MMP2 & MMP3 under normoxia and MMP1 & MMP9 under hypoxia was observed. Treatment of HTR-8/SVneo cells with HGF under hypoxia also led to decrease in TIMP1. Treatment of the cells with HGF led to activation of mitogen activated protein kinases (MAPK) and phosphatidylinositol 3-kinase (PI3K) signaling pathways. Inhibition of MAPK by U0126 and PI3K by LY294002 led to concomitant decrease in the HGF-mediated migration/invasion of HTR-8/SVneo cells. HGF treatment under hypoxia also led to a significant increase in hypoxia inducible factor (HIF-1α) expression. Additionally, inhibition of HIF-1α by siRNA led to decrease in HGF-mediated migration of HTR-8/SVneo cells under hypoxic conditions. Inhibition of HGF activated MAPK and PI3K signaling led to reduction in HIF-1α expression under hypoxia. In conclusion, HGF facilitates HTR-8/SVneo cell migration/invasion by activation of MAPK/PI3K signaling pathways and increased expression of MMPs. HIF-1α has a role in HGF-mediated increase in migration under hypoxic conditions.

HGF promotes HTR-8/SVneo cell migration through activation of MAPK/PKA signaling leading to up-regulation of WNT ligands and integrins that target ß-catenin.

Inadequate migration and invasion of the trophoblast cells during embryo implantation is one of the reasons for pregnancy-related complications such as intrauterine growth restriction and preeclampsia. In the present study, relevance of WNT ligands and integrins associated with hepatocyte growth factor (HGF)-mediated migration of HTR-8/SVneo trophoblastic cells has been investigated. Treatment of HTR-8/SVneo cells with HGF led to a dose-dependent increase in their migration. RT-PCR studies revealed a significant increase in the transcripts of WNT4, WNT11, ITGA2, and ITGAV, which was further confirmed at protein level by Western blotting. HGF treatment also led to increased expression of integrin α2ß1 and αVß5 in HTR-8/SVneo cells. Silencing of WNT4, WNT11, ITGA2, and ITGAV by siRNA led to a significant decrease in HGF-mediated migration of cells. Treatment of cells with HGF led to activation of mitogen-activated protein kinases (MAPK) and protein kinase A (PKA) signaling pathways. Inhibition of MAPK/PKA, by selective inhibitors, led to decrease in the expression of above WNT ligands and integrins. Silencing of WNT4/WNT11 led to concomitant decrease in the expression of ITGA2 and ITGAV and vice versa. HGF treatment also led to significant increase in ß-catenin expression, a downstream target of both WNT ligands and integrins. Silencing of ß-catenin led to decrease in HGF-mediated migration. ß-catenin expression was also down-regulated in WNT4/WNT11/ITGA2/ITGAV silenced cells suggesting a possible cross-communication of WNT ligands and integrins via ß-catenin. These studies have established the significance of WNT4/WNT11 as well as ITGA2/ITGAV during HGF-mediated migration of HTR-8/SVneo trophoblastic cells.