Activation of the receptor protein tyrosine kinase EphB4 in endometrial hyperplasia and endometrial carcinoma

Background: Members of the Eph family of tyrosine kinases have been implicated in embryonic pattern formation and vascular development; however, little is known about their role in the adult organism. We have observed estrogen-dependent EphB4 expression in the normal breast suggesting its implication in the hormone-controlled homeostasis of this organ. Since the endometrium is a similarly hormone dependent organ and endometrial carcinoma is thought to result from estrogenic stimulation, we have investigated EphB4 expression in normal human endometrium and during its carcinogenesis. Patients and methods: EphB4 expression was analyzed immunohistochemically in 26 normal endometrium specimens, 15 hyperplasias and 102 endometrioid adenocarcinomas and correlated with clinical and prognostic tumor characteristics. Results: In normal endometrial tissue no EphB4 protein was detected. Strikingly, we observed a drastic increase (P