ESTRAMUSTINE-BINDING PROTEIN TO DIHYDROTESTOSTERONE RATIO IN HUMAN PROSTATIC-CARCINOMA - A NEW MARKER FOR PREDICTING DISEASE PROGRESSION

Objective To elucidate the clinical significance of estramustine-bindi ng protein (EMBP) in human prostatic carcinoma (PC) as an indicator fo r predicting disease progression. Patients and methods EMBP concentrat ions in prostate tissue samples taken from 35 patients with benign pro static hyperplasia (BPH), 33 patients with prostatic carcinoma (PC) ta ken before treatment, and from nine patients with hormone-refractory P C (hr-PC) were measured by radioimmunoassay using an antibody raised a gainst rat EMBP. The dihydrotestosterone (DHT), prostatic acid phospha tase (PAP), prostate-specific antigen (PSA) and zinc levels in the tis sue were also measured. Results The EMBP concentration in well differe ntiated PC (W-PC) samples was no higher than in samples of BPH tissue, whereas concentrations in moderately differentiated PC (M-PC) acid po orly differentiated PC (P-PC) were significantly higher (P<0.01 and P< 0.005) respectively); the highest levels were those in tissue from hr- PC (P<0.001). Levels of PAP, PSA and zinc were significantly lower in tissue fi om PC than from BPH, while the differences in levels between W-PC, M-PC and P-PC were not significant. The EMBP to DHT ratio in th e tissue increased significantly from W-PC through M-PC to P-PC and wa s greatest in hr-PC tissue. Conversely, the PAP:DHT, PSA:DHT and zinc: DHT ratios did not correlate with the progress of histological grade. Ln addition, the pre-treatment EMBP:DHT and zinc:DHT ratios in 14 pati ents who developed hr-PC within 3 years after the administration of es tramustine phosphate were significantly higher when compared with the remaining 19 patients (P<0.001 and P = 0.0184, respectively). whereas the PAP:DHT and PSA:DHT ratios showed no significant difference bet iz een the groups. Moreover, patients with a high EMBP:DHT ratio (greate r than or equal to 82) had a low progression-free probability compared to those with a lower ratio. Conclusion The androgen-dependent proper ty of EMBP tends to decline with the transformation of prostatic tissu e into biologically more malignant disease. The tissue EMBP:DHT ratio before treatment may be a good indicator of the individual malignant p otential of PCs.