EXPRESSION OF TUMOR-ASSOCIATED GLYCOPROTEIN-72 IN PROSTATIC INTRAEPITHELIAL NEOPLASIA AND PROSTATIC ADENOCARCINOMA

Tumor-associated glycoprotein 72 is a high-molecular-weight sialomucin that is expressed selectively in various adenocarcinomas, including t hose of the prostate. We utilized the monoclonal antibodies B72.3 and CC49 to examine the expression of TAG-72 in high-grade prostatic intra epithelial neoplasia (PIN), localized adenocarcinomas (pathologic stag es B and C), as well as matching primary and nodal lesions from patien ts with stage D adenocarcinomas. Immunoreactivity within PIN lesions w as detected within 20 (87%) and 17 (74%) of 23 specimens immunostained with B72.3 and CC49, respectively. Benign epithelium and stromal tiss ue did not immunostain with either antibody at the concentrations test ed. Immunostaining was detected within the malignant cells in 30 (77%) and 35 (90%) of 39 localized adenocarcinomas using B72.3 and CC49, re spectively. Immunostaining was localized to the cytoplasm and cellular membranes of the malignant cells and within the lumen of malignant gl ands. Seven of 17 (41%) primary lesions from patients with stage D ade nocarcinomas demonstrated immunoreactivity when stained with B72.3. Im munoreactivity was detected in 8 of 10 (80%) of these tissues immunost ained with CC49. Within nodal lesions obtained from these patients, im munostaining was observed in 3 of 17 (18%) and 6 of 10 (60%) of the sp ecimens immunostained with B72.3 and CC49, respectively. We used a sem iquantitative technique to compare the extent of immunoreactivity amon g well-differentiated (Gleason score <6), moderately differentiated (G leason 6-7), and poorly differentiated (Gleason score >7) tumors. We o bserved an inverse correlation of TAG-72 expression to Gleason scores. Furthermore, TAG-72 expression was reduced in the matching primary an d metastatic lesions of stage D adenocarcinomas as compared to localiz ed lesions. These findings demonstrate a phenotypic relationship of PI N to invasive adenocarcinomas and support the concept that PIN is a pr einvasive neoplastic lesion. Furthermore, expression of TAG-72 may rep resent an early event in the neoplastic transformation of the prostati c epithelium. The data demonstrate a diminution in TAG-72 expression i n poorly differentiated and advanced-stage prostatic adenocarcinomas.