Androgen receptor binding activity in human prostate cancer

Androgen binding (cytosol and nucleus) was measured in tissue obtained from 223 untreated patients with proven prostate cancer (199 primary tumor, 24 malignant lymph nodes), 19 patients with hormone refractory cancer, and 46 patients with benign prostatic hyperplasia (BPH). The mean binding in both the cytosol and nucleus was significantly higher for patients with cancer than for those with BPH. Binding appeared to correlate with tumor stage. Androgen binding in malignant nodes can differ from that in the primary tissue and can vary from node to node in the same patient. Results obtained from an assay using a single saturating concentration of R1881 correlated well with those calculated from a full six‐point Scatchard analysis when an adequate amount (500 mg) of tissue was available. However, binding results obtained from a single‐point analysis performed on needle biopsy specimens (about 50 mg) obtained before complete surgical removal of the prostate correlated poorly with those derived from a full six‐point analysis performed on tissue (500–1000 mg) removed from the center of the malignancy. Androgen binding in nuclear extracts of histologically benign tissue adjacent to the malignancy was significantly higher than in nuclear extracts of BPH tissue. Cytosolic androgen binding in tissue removed from patients who were refractory to hormonal therapy was higher than in tissue from untreated cancer patients. The binding of estradiol by extracts of benign and malignant prostate tissue was low or absent and, thus, did not appear to be a significant phenomenon.