INVOLVEMENT OF EPIDERMAL GROWTH-FACTOR (EGF) EGF RECEPTOR AUTOCRINE AND PARACRINE MECHANISM IN HUMAN TROPHOBLAST CELLS - FUNCTIONAL-DIFFERENTIATION IN-VITRO

We have studied the expression of epidermal growth factor (EGF) and EG F receptors (EGF-R) in isolated human trophoblast cells at various sta ges of differentiation and also the biological significance of the EGF /EGF-R autocrine and paracrine mechanism. Cytotrophoblast cells were i solated from human placental tissues of 6-9 weeks of gestation. Tropho blast cells underwent morphological and functional differentiation dur ing in vitro culture. The expression of EGF and EGF-R protein and mRNA was studied in trophoblast cells cultured for 0-5 days, using immunoc ytochemical staining, and reverse transcription and polymerase chain r eaction. Monoclonal antibodies (mAbs) against EGF and EGF-R showed spe cific staining in trophoblast cells at all stages of differentiation. Both EGF and EGF-R gene transcripts were detected in RNA samples isola ted from trophoblast cells at all stages. These data suggest the prese nce of an EGF/EGF-R autocrine and paracrine mechanism in human trophob last cells. Next, we examined the biological significance of this mech anism on trophoblast cell differentiation in vitro. EGF added to the c ulture medium significantly increased human chorionic gonadotrophin-be ta (hCG-beta) secretion and, more importantly, anti-EGF neutralizing m Abs sig nificantly reduced both hCG-beta and human placental lactogen secretion from trophoblast cells in culture. All these results suggest that human trophoblast cells express both EGF and EGF-R, and that EGF may play an important role in the functional differentiation of human trophoblast cells.