ZFP91-a newly described gene potentially involved in prostate pathology.

In search for novel molecular targets in benign prostate hyperplasia (BPH), a PCR Array based screening of 84 genes was performed. Of those, expression of ZFP91 (ZFP91 zinc finger protein) was notably upregulated. Limited data concerning the function of ZFP91 product show that it is a potential transcription factor upregulated in human acute myelogenous leukemia and most recently found to be the non-canonical NF-κB pathway regulator. In order to test this finding on a larger number of samples, prostate specimens were obtained from patients undergoing adenomectomy for BPH (n = 21), and as a control, from patients undergoing radical cystectomy for bladder cancer (prostates unchanged pathologically, n = 18). Similar studies were performed on cultured human prostate cancer cell lines: LNCaP, DU145, 22Rv1, PC-3; as well as normal prostate epithelial cells-PrEC. Methods employed included: Human Obesity PCR Array (Qiagen), QPCR and Western blotting. QPCR studies confirmed significant overexpression of ZFP91 in BPH samples. On a protein level, however, comparison between normal and BPH prostates revealed insignificant differences. As for prostate cell lines examined, all expressed ZFP91 mRNA. Western blotting analysis showed markedly higher protein levels of ZFP91 in all cancer cell lines in comparison with normal (PrEC) cells. In conclusion, the upregulated ZFP91 mRNA in BPH, not accompanied by parallel changes in ZFP91 protein levels, together with ZFP91 protein abundance in prostate cancer cell lines suggest ZFP91 involvement in these prostate diseases.

Elevated expression of orexin receptor 2 (HCRTR2) in benign prostatic hyperplasia is accompanied by lowered serum orexin A concentrations.

In search for the new polypeptides responsible for energy homeostasis which are also involved in regulating the growth and function of the human prostate, we assessed the expression of orexins (OXs) and of orexin receptors (OXRs) in human normal prostate and in benign prostatic hyperplasia (BPH). Conventional RT-PCR revealed the expression of OXR2 in all studied samples obtained either from normal prostates or BPH ones while neither preproorexin (ppOX)nor OXR1 mRNA were detected. In adenomatous prostates, expression levels of OXR2 were 30- to 40-fold higher compared to controls. Western blot analysis demonstrated the presence of OXR2 protein in the studied samples and its expression levels were 4-fold higher in tissue samples from BPH. In normal glands, presence of OXR2-like immunoreactivity was found in the apical parts of epithelial cells as well as in smooth muscle cells of the stroma. Immunostaining for OXR2 was more intense in sections obtained from BPH. Immunohistochemistry did not detect the expression of OXR1-like protein. OXA serum concentrations were lowered in BPH patients (mean ± SE 56±4 ng/ml, n=12; P<0.01) and unaltered in prostate cancer (79±7 ng/ml, n=18) compared to the controls (69±2 ng/ml, n=16). On the contrary, serum OXB levels were similar in all studied groups of patients. We thus have demonstrated the mRNA and protein expression of OXR2, but not of ppOX and OXR1 in both normal and BPH human prostate glands. We also demonstrated notable up-regulation of OXR2 in benign prostatic hyperplasia, an alteration accompanied by lowered serum OXA concentrations. These findings suggest that both OXA and OXR2 may be involved in the pathogenesis and/or maintenance of BPH.

Elevated blood active ghrelin and unaltered total ghrelin and obestatin concentrations in prostate carcinoma.

PURPOSE: Ghrelin and its functional receptor are highly expressed in prostate cancer (PC) and ghrelin may activate proliferation of PC cell lines. This study was therefore designed to characterize the association between serum acylated and total ghrelin, and obestatin levels in patients with benign prostate hyperplasia (BPH) and PC. METHODS: Blood serum concentrations of active and total ghrelin and obestatin were estimated by EIA methods. RESULTS: Serum level of active ghrelin in PC was significantly higher compared to control and BPH groups. On the other hand, concentrations of total ghrelin and of obestatin did not differ between studied groups of patients. In the control group the ratio of active to total ghrelin concentrations amounted to 0.16, and it was similar in BPH (0.14), while it was notably elevated in PC (0.42). Also the ratio of active ghrelin to obestatin concentrations was higher in the group with PC than in the control and BPH groups. In all studied groups, the ratio of total circulating ghrelin to obestatin was similar. CONCLUSIONS: Obtained results suggest the link between elevated blood active ghrelin and PC, and we cannot exclude that elevated circulating active ghrelin may affect growth of malignant prostatic tissues.

Real-time PCR analysis of leptin and leptin receptor expression in the rat prostate, and effects of leptin on prostatic acid phosphatase release.

We have recently demonstrated the expression of leptin and leptin receptor (Ob-R) isoforms a, b, c, e and f in the rat seminal vesicles and prostate. The aim of the present study was to provide a semiquantitative real-time PCR estimation of leptin/Ob-R isoform mRNA expression in the seminal vesicles and individual components of rat prostate, and to ascertain the in vitro effects of leptin on prostate acid phosphatase release. The highest expression of the leptin and Ob-R genes was in the seminal vesicles and lateral prostate lobe, respectively. Of the various isoforms, Ob-Rb displayed the highest and Ob-Re the lowest expression. Leptin (10(-8) and 10(-6) M) enhanced acid phosphate release from seminal vesicles, and (10(-6) M) decreased it from the coagulating lobe. Taken together, our findings support the contention that leptin may be involved in the autocrine-paracrine functional regulation of rat seminal vesicles and prostate. The physiological relevance of the marked heterogeneity of the different prostate lobes in both their leptin/Ob-R expression and functional response to leptin remains to be addressed.

Leptin and leptin receptors in the prostate and seminal vesicles of the adult rat.

Leptin is an adipose tissue-secreted hormone that acts via specific receptors (Ob-R), of which six isoforms are at present recognized (from Ob-Ra to Ob-Rf). Ob-Rb is the only isoform able to activate JAK-STAT and MAPK signaling cascades. A large body of evidence suggests that leptin and its receptors are involved in prostate physiology and pathophysiology in humans, but studies on the leptin system in the rat prostate are lacking. Reverse transcription-polymerase chain reaction showed the expression of mRNAs of leptin, Ob-Ra, Ob-Rb, Ob-Rc, Ob-Re and Ob-Rf in adult rat seminal vesicles and prostate (coagulating, dorsal, ventral and lateral lobes). Western blotting demonstrated the presence in these specimens of the Ob-Rb protein, and immunocytochemistry revealed that Ob-Rb was mainly located in their epithelial-cell component. Collectively, these findings strongly suggest that leptin and Ob-R may be involved in the autocrine-paracrine functional regulation of the epithelial cells of adult rat seminal vesicles and prostate.