An immunohistochemical technique for localization and semiquantitation of estramustine-binding protein (EMBP) in rat...

An immunohistochemical technique for determination of "estramustine-binding protein" (EMBP) in rat prostate is described. The localization and staining intensity of this protein were correlated to prostatic morphological structures in intact animals and at different time intervals after androgen deprivation by castration. EMBP was found almost exclusively in epithelial cells, while the fibromuscular stroma seemed to be negative. Intracellularly, immunostaining was confined to the cytoplasm, but was absent in nuclei. In intact rats, acinar lumina demonstrated heavy immunostaining, indicating secretion of EMBP. Orchiectomy caused a diminution of EMBP expression as well as secretion, suggesting that EMBP synthesis is under androgenic regulation. Human benign hyperplastic and cancerous prostatic specimens were also examined. All human specimens examined so far exhibited positive epithelial staining although of varying intensity. Therefore, this immunohistochemical technique may be used for studying the correlation of EMBP with tumor malignancy grade and for clinical investigations of how various treatments affect EMBP expression in prostatic carcinomas.