Expression of Zn-alpha 2-glycoprotein and PSP-94 in prostatic adenocarcinoma. An immunohistochemical study of 88 cases.

Zn-Alpha 2-Glycoprotein (Zn-Alpha 2-GP) and prostatic secretory protein of 94 amino-acids (PSP-94) were recently isolated from the human prostate. Their expression in benign and malignant well-differentiated and poorly differentiated components of 88 prostates with prostatic adenocarcinomas, and in 25 metastases, was evaluated using polyclonal antibodies developed against these antigens. Zn-Alpha 2-GP was present in benign hyperplastic glands in 91.1% of cases, but in only 40.7% (poorly differentiated component) to 48.5% (well-differentiated component) of prostatic adenocarcinomas, and in 8% of metastases. The expression of PSP-94 was present in 89.3% of benign hyperplastic glands, but in only 50% (well-differentiated adenocarcinoma component) to 57.3% (poorly differentiated component) of prostatic adenocarcinomas and 28% of metastases. The expression of these proteins by the tumor was unrelated to the initial stage and the tumor grade. Because of their low frequency in prostatic adenocarcinomas, especially in metastases, Zn-Alpha 2-GP and PSP-94 appear to have a limited diagnostic usefulness. Further studies are needed, however, to explore other clinical applications of these two new prostatic secretory proteins.