Invasion of cytotrophoblastic JEG-3 cells is stimulated by hCG in vitro

Trophoblast invasion into the uterine wall is controlled by many factors. Previously, a human chorionic gonadotropin (hCG) receptor has been found to be expressed on invasive trophoblast as well as on choriocarcinoma cells implying a possible role for the hormone in trophoblast invasion. Therefore, this study examined the role of hCG in the invasion of trophoblastic (JEG-3) cells. Increasing hCG concentrations were applied in a trophoblast invasion model, JEG-3, through matrigel-coated filters. The proliferation was quantified by WST-1 cleavage assay. Cell migration was studied by examining the number of cells that had passed the uncoated porous (8-microm pore size) filters. After staining, filters were examined microscopically for cells on the underside of the membrane. A quantitative protease assay was also performed. Flow cytometric analysis of alpha5 and alpha6 integrin subunits, which are essential for interactions between cells and extracellular matrix, was performed. hCG increased significantly (P<0.01) the in vitro invasion of trophoblastic JEG-3 cells in a dose-dependent manner. Migration was also increased by hCG (P<0.01). However, cell proliferation remained unchanged. The second messenger analogue dibutyryl cAMP (db cAMP) and the cAMP elevating factor (forskolin) mimicked the effects of hCG by stimulating a dose-dependent increase of trophoblastic cell UEG-3) invasion. The collagenolytic activity of trophoblastic cells (EG-3) was increased by hCG stimulation. No changes were shown in the expression of alpha5 and alpha6 integrin subunits on JEG-3 cells. In vitro hCG is a regulatory factor of invasion and migration in trophoblastic JEG-3 cells, whereas proliferation is not influenced. The endogenous production of hCG by the trophoblast in vivo implies an autocrine control of invasion processes by hCG.