Ep-CAM levels in prostatic adenocarcinoma and prostatic intraepithelial neoplasia

Purpose: The monoclonal antibody (mAb) 323/A3, a second generation high aff inity antibody of the 17-1A antibody family, recognizes a 40 kDa transmembr ane glycoprotein that has been referred to as Ep-CAM, 17-1A recognized anti gen, or EGP40. While Ep-CAM is expressed on the basolateral surface of a va riety of epithelia, the strongest expression is frequently detected among s everal types of carcinoma. In this regard, Ep-CAM may be useful in therapy, in diagnosis, and/or in prognosis. We examined the distribution of Ep-CAM in normal, dysplastic, and malignant prostatic epithelium. Materials and Methods: Paraffin sections of prostate tissue from 76 patient s with clinically localized (pT2) prostatic adenocarcinoma were immunostain ed with mouse mAb 323/A3 using the avidin-biotin horseradish peroxidase met hod. Results: Within benign prostatic epithelium, immunoreactivity typically was low and frequently was restricted to the luminal cells. In contrast, moder ate to strong immunostaining was detected frequently in the luminal cells o f high grade prostatic intraepithelial neoplasia (PIN). Furthermore, strong immunostaining usually was detected in the cells of adenocarcinomas. The i mmunostaining in PIN (p <0.0001) and in adenocarcinoma (p <0.0001) was sign ificantly greater than that observed in the normal epithelium. Expression o f Ep-CAM did not vary significantly with the Gleason score of tumors or the clinical outcome of patients. Expression of Ep-CAM was demonstrated also i n the malignant prostatic cell Lines LNCaP, DU145 and PC3 using immunohisto chemistry and an immunoblot technique. Conclusions: These findings suggest that increased levels of Ep-CAM represe nt an early event in the development of prostatic adenocarcinoma.