Androgen receptor isoforms in human and rat prostate

Aim: To investigate the androgen receptor (AR) isoforms and its variability of expression in human and rat prostatic tissues. Methods: Human benign pr ostatic hyperplasia (BPH) and prostatic cancer tissues were obtained from p atients undergoing-prostatectomy, and rat ventral prostate was incised 3 da ys after castration. Forty-one AR-positive BPH specimens, 3 prostatic cance r specimens, and 6 rat prostates were used. After processing at 4 degreesC, the tissues were examined by means of high resolution isoelectric focusing (IEF) technique to determine their AR isoforms. Results: From the prostati c specimens, 3 types of AR isoforms were detected with pI values at 6.5, 6. 0, and 5.3. In human BPH tissues, 15/41 (36.6%) specimens showed all the th ree types of isoforms, while 19/41 (46.3%) showed 2 isoforms at various com binations and 7/41 (17.1%), 1 isoform. For the 3 prostatic cancer specimens , one showed 3 isoforms, one, 2 isoforms, and the other failed to show any isoform. All rat prostatic tissues showed 2 isoforms at different combinati ons. Binding of H-3-dihydrotestosterone (DHT) to the isoforms was inhibited by the addition of 100-fold excess of DHT or testosterone, but not progest erone, oestradiol or diethylstilboestrol. Conclusion: AR isoforms are diffe rent in different patients. Although their genesis is not clear, the therap eutic implication of the present observation appears to be interesting, tha t may help clarifying the individual differences in the response to hormona l therapy.