Study of estramustine binding protein: its relationship to androgen dependency and histological differentiation in human prostatic carcinoma tissue

Platinum(IV)-Estramustine Multiaction Prodrugs Are Effective Antiproliferative Agents against Prostate Cancer Cells

Herein, we describe the synthesis, characterization, and biological properties of Pt(IV) derivatives of cisplatin with estramustine at the first axial position, which is known to disrupt the microtubule assembly and act as an androgen antagonist, and varying the second axial position using an innocent ligand (acetate or hydroxyl) to prepare dual-action and triple-action prodrugs with known inhibitors of histone deacetylase, cyclooxygenase, and pyruvate dehydrogenase kinase. We demonstrate superior antiproliferative activity at submicromolar concentrations of the prodrugs against a panel of cancer cell lines, particularly against prostate cancer cell lines. The results obtained in this study exemplify the complex mode of action of "multiaction" Pt(IV) prodrugs. Interestingly, changing the second axial ligand in the Pt-estramustine complex has a significant effect on the mode of action, suggesting that all three components of the Pt(IV) prodrugs (platinum moiety and axial ligands) contribute to the killing of cells and not just one dominant component.

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.

Inhibitory effects of Serenoa repens on the kinetic of pig prostatic microsomal 5alpha-reductase activity

The pathogenesis of benign prostatic hyperplasia is linked to the accumulation of dihydrotestosterone (DHT), the active form of testosterone (T), in prostatic tissue. We have defined characteristics of 5alpha-reductase enzyme which catalyzes the conversion of T into DHT in prostatic microsomes of growing pigs. Peaks for the 5alpha-reductase activity were found at pH 5.5 and 8.0, which indicates the presence of both type 1 and type 2 isozymes. Kinetic parameters of porcine 5alpha-reductase in the presence of Serenoa repens extracts revealed uncompetitive, noncompetitive, and mixed types of inhibitions. Our results show the inhibitory action of S. repens on prostate porcine microsomal 5alpha-reductase activity.

Immunohistochemical analysis of estramustine binding protein with particular reference to proliferative activity in human prostatic carcinoma

BACKGROUND

The estramustine binding protein (EMBP) specifically binds to estramustine and was first discovered in the rat ventral prostate. However, the physiological property of EMBP in the human prostate still remains to be elucidated. To elucidate whether EMBP is interrelated with cellular proliferation in human prostatic carcinoma (PC), the change in EMBP immunostaining during luteinizing hormone-releasing hormone (LH-RH) analog administration or during Cis-platinum-based chemotherapy, and the difference in EMBP immunostaining between hormone refractory (hr-PC) and untreated PC were analyzed.

METHODS

Forty-six patients with histologically proven untreated PCs (34 were treated with LH-RH analog and 12 were treated with chemotherapy as an initial therapy) and 14 with hr-PC were used in this study. PC tissues were obtained before and 3 months after the initial therapy. The changes in immunostainings for EMBP, proliferating cell nuclear antigen (PCNA), and nm23 protein were compared with the change in serum prostate-specific antigen (PSA) level and the histological response during the treatment.

RESULTS

The increased EMBP expression was observed in tumors with high histological grade and high clinical stage as well as in hr-PC. In untreated PC, EMBP expression weakly correlated with PCNA or nm23 protein immunoreactivity. In PC receiving LH-RH analog, EMBP expression was significantly reduced after treatment, however, no significant changes were observed in PCNA or nm23 protein immunoreactivity. In addition, EMBP expression before the treatment significantly correlated with the serum PSA change, while PCNA expression and nm23 protein immunoreactivity did not. On the other hand, no significant relationship was observed between histological changes induced by the LH-RH analog and immunostainings for EMBP, PCNA, and nm23 protein before treatment. In PC patients receiving chemotherapy, immunostainings for EMBP, PCNA, and nm23 protein were not significantly changed during the treatment. EMBP immunoreactivity was significantly higher in hr-PC than in untreated PC with paralleled change of PCNA expression and nm23 protein immunoreactivity.

CONCLUSIONS

These observations indicate that EMBP is androgen regulated in some PCs. However, EMBP expression is demonstrated even in hr-PC and is interrelated with cellular proliferation especially in hr-PC.

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.