DISTANT METASTASES FROM PROSTATIC-CARCINOMA EXPRESS ANDROGEN RECEPTORPROTEIN

Nearly all primary prostatic carcinomas have been found to express the androgen receptor (AR) protein, which is the intracellular mediator o f androgen action. To gain a better insight into the mechanisms of and rogen independence of advanced prostatic carcinoma, it is important to know whether the AR is also present in metastases of androgen-indepen dent tumors. We have assessed the status of the AR and the prostate-sp ecific antigen in 22 metastases of 18 patients with progressive prosta te cancer. In 18 cases, the metastases were localized in bone, in 3 ca ses in the epidural space, and in 1 case in the periosteum. All but on e patient had received some kind of endocrine treatment for prostatic carcinoma. Paraffin-embedded tissue sections were stained for the AR f ollowing a streptavidinbiotin-peroxidase protocol with the polyclonal antibody PG-21, which is directed against amino acids 1 through 21 of the rat and the human AR. The percentage of AR-positive cells was eval uated on the basis of an arbitrary 4-point scale. All 22 tumor metasta ses displayed AR positivity, One AR-positive metastatic lesion did not stain for prostate-specific antigen, but in all other metastases, thi s protein was detected by means of immunohistochemistry. The present s tudy provides evidence that, unlike androgen-independent prostatic car cinoma cell lines, distant prostatic carcinoma metastases do express t he AR. These findings indicate that the AR may be involved in the prog ression of prostate cancer.