Localization of epidermal growth factor receptor by immunohistochemical methods in human prostatic carcinoma, prostatic intraepithelial neoplasia, and benign hyperplasia.

The epidermal growth factor receptor (EGFr) is a membrane-bound glycoprotein that is present in a wide variety of human normal and malignant tissues. In this study EGFr expression in frozen sections of prostate tissue obtained from 40 different surgical specimens was examined immunohistochemically with a well-characterized monoclonal antibody to EGFr, Ab-1 (Oncogene Science). Twenty cases of prostate adenocarcinoma and 20 cases of benign prostatic hyperplasia were studied. Six of the 20 cases of adenocarcinoma also contained prostatic intraepithelial neoplasia grade III (severe intraductal dysplasia). All of the cases containing benign glands showed strong immunostaining in a continuous or nearly continuous pattern, with staining restricted to the basal layer of the benign glands. Adenocarcinoma lacked immunostaining in 15 (75%) of 20 cases, while the remaining five cases (25%) showed diffuse cytoplasmic staining, which was weaker than that seen in the benign glands and that lacked basal accentuation. The six cases that contained prostatic intraepithelial neoplasia grade III showed a discontinuous basal pattern of staining, and the gaps in the staining appeared to correspond to areas of disruption of the basal cell layer. We conclude that the antigenic determinant recognized by this antibody to EGFr was detected preferentially in the basal layer in benign prostatic glands. In contrast, a minority of cases of adenocarcinoma expressed EGFr, as assessed by immunoreactivity with the Ab-1 monoclonal antibody. Prostatic intraepithelial neoplasia grade III expressed EGFr with a predominantly discontinuous basal pattern that corresponded to the disrupted basal cell layer typical of this process.