Estramustine binding protein in human benign prostatic hypertrophy

Identification of rat prostatic steroid binding protein (PSBP) as an immunosuppressive factor

Prostatic steroid binding protein (PSBP) is the major protein produced ( approximately 20% of the total cytosolic protein) and secreted into the seminal fluid by the rat ventral prostate but its physiological function has not been elucidated yet. Since PSBP is secreted into the seminal fluid (which is itself a potent immunosuppressor) and has strong homology with uteroglobin (which possess an important anti-inflammatory function) our aim was to determine what effect, if any, PSBP would have on the immune system. With that purpose in mind we performed mononuclear cell cultures in the presence or absence of purified PSBP and analysed the effect of this protein on different functional parameters. PSBP inhibits the mitogen-induced proliferation of normal rat spleen mononuclear cells (MNC) specifically and in a dose-dependent manner. It reduces the production of IL-2 and the expression of its receptor (analysed by flow cytometry) which are important events for lymphocyte proliferation. Also, PSBP was able to inhibit OVA-specific proliferation of lymph node cells from previously primed animals. The immunosuppressive effect of PSBP is not due to an inherent toxic effect to the cells, since the cell viability was kept intact at the different times of culture studied. We also analysed the effect of rat PSBP on mitogen-induced proliferation of mouse spleen and human blood MNC. The proliferation was strongly abolished in a dose-dependent and non-species specific fashion. Moreover, PSBP strongly inhibits the human mixed lymphocyte reaction. Taken together, the present data support evidence for a new type of function for PSBP. We report that PSBP is a potent immunosuppressor factor and we describe its effect on the immune function in vitro. Here, we discuss the possible implications of these findings in the protection of sperm from immunologic damage in the feminine reproductive tract.

Radioiodinated estramustine phosphate and estramustine binding protein antibody accumulate in the prostate of a mouse

BACKGROUND

The purpose of this study was to determine the distribution of radioiodinated estramustine (RI-EMP) and a radioiodinated antibody against estramustine binding protein (RI-EMBP-AB) in mice.

METHODS

RI-EMP and RI-EMBP-AB were injected in male mice intravenously, and the activities of tissue samples were measured 1-31 hr from the injection. Pure iodine-125 (RI) was used as a control.

RESULTS

RI-EMP accumulated in the prostate, which contained 2.6% of injected activity (ID) per gram tissue at 7 hr. The liver had an activity of 21.4% ID/g at 1 hr, which decreased as RI-EMP was secreted in bile. The lung contained 2.3% ID/g at 7 hr, and it retained the activity longer than the prostate. RI-EMBP-AB accumulated in the prostate: The activity was 2.9% ID/g at 7 hr. The gallbladder contained 6.5% ID/g at 7 hr.

CONCLUSIONS

Due to its cytotoxic and radiosensitizing properties, RI-EMP can possibly be used for treating prostate cancer and other tumors.

Relationship of thyroid to estramustine binding protein (EMBP) concentration in rat prostate

Alternations of estramustine binding protein (EMBP) concentration in rat prostate in relation to androgen status under hypo- and hyperthyroid conditions was estimated by means of radioimmunoassay (RIA). In hyperthyroid rats, EMBP concentration in dorsal as well as in lateral prostate was not significantly changed, but significantly reduced in ventral prostate (P less than 0.01). Ventral tissue concentration of testosterone(T) + dihydrotestosterone (DHT), DHT and T, and the ventral tissue ratio of DHT to T + DHT were not significantly changed in hypo- and hyper-thyroid conditions compared with that of the control. In hyperthyroid rats, serum T level and EMBP concentration in ventral prostate were significantly reduced in comparison to ones of the control (P less than 0.05 and P less than 0.01, respectively), however, the ratio of ventral tissue (T + DHT) to serum T was significantly increased (P less than 0.05). Moreover, in contrast to the control, EMBP concentration expressed as microgram/microgram ventral DNA was significantly reduced in hyperthyroid rats (P less than 0.05). On the other hand, in hypothyroid rats, change of EMBP concentration in ventral prostate in relation to androgen status was not significant in comparison to the control. The results here obtained revealed that EMBP concentration in ventral prostate under hyperthyroid condition would be affected by (a) a modulation of endogenous androgen-dependency in EMBP synthesis or by (b) a reduction of cell numbers responsible for EMBP synthesis.