EphrinA1 stimulates cell attachment and inhibits cell aggregation through the EphA receptor pathway in human endometrial carcinoma-derived Ishikawa cells

Abstract

Recently, the Eph-ephrinA system was proposed to contribute to the initial interaction between the maternal endometrial epithelium and embryonic trophectoderm. Since the Eph-ephrin interaction can induce adhesive and/or repulsive forces into the cells, we examined the possible role of this system in functional changes in endometrial epithelial cells using endometrial carcinoma-derived Ishikawa cells. The expressions of EphA1, A2 and A4 on Ishikawa cells were examined by RT-PCR and western blotting analyses. The effects of recombinant ephrinA1 on Ishikawa cells were also examined by western blot analysis and cell attachment and aggregation assays. EphA1, A2 and A4 were expressed on Ishikawa cells. Recombinant ephrinA1 bound to the surfaces of Ishikawa cells and induced phosphorylation of EphA2 and A4. In bovine serum albumin-blocked nitrocellulose-coated dishes, Ishikawa cells remained floating and aggregated with each other. Under these conditions, immobilized ephrinA1 promoted Ishikawa cell attachment with increased tyrosine phosphorylation in focal adhesion kinase. In addition, immobilized ephrinA1 reversibly inhibited Ishikawa cell aggregation. Gene-reduction of EphA1, A2 and A4 by siRNAs attenuated the inhibitory effects of ephrinA1 on cell aggregation, confirming that ephrinA1 affects Ishikawa cell functions through Eph-ephrinA interaction. This study demonstrated that the Eph-ephrinA system can promote cell attachment along with intercellular dissociation in Ishikawa cells. These findings suggest that this system can induce functional changes in endometrial epithelial cells.