Study of estramustine binding protein: its relationship to androgen dependency and histological differentiation in...

For the purpose of elucidating the clinical significance of estramustine binding protein (EMBP), EMBP concentration in human prostatic carcinoma (PC) tissue was measured by radioimmunoassay (RIA) using an antibody raised against rat EMBP and was compared with dihydrotestosterone (DHT) level and histological differentiation in the same tissue. The mean concentrations of EMBP in 20 untreated and 6 hormonally refractory PC were 112.6 +/- 120.7 and 218.0 +/- 102.3 ng/g tissue, respectively. In the 20 untreated PC, the EMBP concentration was not significantly different between the high and low tissue DHT groups. On the other hand, the EMBP concentration was significantly higher in moderately and poorly differentiated PCs as compared with well-differentiated PC, whereas the DHT level was highest in well-differentiated and lowest in poorly differentiated PC. Furthermore, in the 6 hormonally refractory PC, the EMBP concentration was higher in spite of a lower tissue DHT level in comparison with untreated PC. These results suggest that the EMBP concentration does not reflect androgen status in PC tissue but might reflect the malignant potential of the tumor.