A stuby on expression mechanisms and functions of a novel adhesion molecule, trophinin

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Trophinin is one of the adhesion molecules showing the homophilic manner. This protein was cloned by an expression cloning technique using HT-H cell derived from teratocarcinoma and SNG-M from uterine endometrial cancer, which adhere to each other. Since there is a possibility that trophinin could be a mediator for proliferation and progression of cells such as chorionic cells or endometrial cancer cells if they expressed it, we first invesdgated its expression manner on early placenta, hydatidiform mole, choriocarcimoma, and endometrial adenocarcinoma. The immunohistochemical investigation using the monoclonal antibody against the recombinant peptide corresponding to the functional domain in trophinin revealed that the immunoreacitve protein was seen in syncytiotrophoblasts of early placenta and hydatidiform mole, but not in choriocarcimoma or endometrial adenocarcinoma cells. Regarding to an intensity of the immunoreactivity in situ, the strongest positive reaction seen on the normal placental tissue was decreased in molar tissue, then disappeared in choriocarcinoma, suggesting that trophinin is involved with the metastatic activity of the malignant cells.Since trophinin is thought to divide an important role of the adhesion or attachment between blastcyst and endometrial epithelium and to be strictly regulated due to the menstrual cycles, we secondly examined the changes of its expression in various phases of endometrium. The analysis by competitive RT-PCR using total RNA taken from human endometrial tissue showed that the relative expression of trophinin transcripts reached the highest at the late proliferative phase. These findings suggest that the expression of trophinin is regulated by the hormonal changes which create the menstrual cycle.