Neuroendocrine peptides in the prostate

Cocaine and amphetamine regulated transcript (CART): a newly characterized neuropeptide in human prostate

Cocaine and amphetamine regulated transcript (CART) is a somatostatin-like polypeptide. CART has been localized in the CNS, hypothalamo-pituitary-adrenocortical (HPA) axis, pancreatic islets and enteric nervous system. We investigated the cellular localization of CART in normal human prostate, benign prostatic hyperplasia, prostatic intraepithelial neoplasia and acinar adenocarcinoma. CART was assessed using immunohistochemistry (IHC) and in situ hybridization (ISH), and its gene expression was identified by RTqPCR. We found cellular expression of CART in both normal prostatic luminal secretory epithelial cells neuroendocrine cells (NEC) of both ducts and acini. The cellular appearance indicated a cycle of neuropeptide synthesis and secretion as validated by ISH/IHC concordance. RTqPCR analysis also validated the immunohistochemical data and gene expression, which both indicated low to moderate expression in prostatic tissues. CART expression also was increased in both neuroendocrine and glandular epithelial cell populations from samples of benign prostatic hyperplasia as validated by IHC, ISH and RTqPCR. CART expression was markedly diminished and, in some cases, entirely absent in tissues of prostatic intraepithelial neoplasia and adenocarcinoma. Owing to loss of CART expression in adenocarcinoma and its increase in benign prostatic hyperplasia, CART may prove to be an important prostate marker.

Interplay of Epidermal Growth Factor Receptor and Signal Transducer and Activator of Transcription 3 in Prostate Cancer: Beyond Androgen Receptor Transactivation

Prostate cancer (PCa) is one of the most common cancers in the world and causes thousands of deaths every year. Conventional therapy for PCa includes surgery and androgen deprivation therapy (ADT). However, about 10-20% of all PCa cases relapse; there is also the further development of castration resistant adenocarcinoma (CRPC-Adeno) or neuroendocrine (NE) PCa (CRPC-NE). Due to their androgen-insensitive properties, both CRPC-Adeno and CRPC-NE have limited therapeutic options. Accordingly, this study reveals the inductive mechanisms of CRPC (for both CRPC-Adeno and CRPC-NE) and fulfils an urgent need for the treatment of PCa patients. Although previous studies have illustrated the emerging roles of epidermal growth factor receptors (EGFR), signal transducer, and activator of transcription 3 (STAT3) signaling in the development of CRPC, the regulatory mechanisms of this interaction between EGFR and STAT3 is still unclear. Our recent studies have shown that crosstalk between EGFR and STAT3 is critical for NE differentiation of PCa. In this review, we have collected recent findings with regard to the involvement of EGFR and STAT3 in malignancy progression and discussed their interactions during the development of therapeutic resistance for PCa.

Gastrin-Releasing Peptide Receptor in Low Grade Prostate Cancer: Can It Be a Better Predictor Than Prostate-Specific Membrane Antigen?

The aim of the present study was to evaluate whether prostate cancer (PC) patients can be accurately classified on the bases of tissue expression of gastrin-releasing peptide receptor (GRPR) and prostate-specific membrane antigen (PSMA). This retrospective study included 28 patients with PC. Formalin-fixed paraffin-embedded samples were used for diagnosis. Immunohistochemistry staining techniques were used to evaluate PSMA and GRPR expression (both number of cells expressed and % of area stained). To assess the independent associations among selected variables, a multi-dimensional scaling (MDS) analysis was used. It was found that the PSMA expression was inversely correlated with GRPR expression. Only the number of cells expressing GRPR was significantly related to the Gleason score. Both the percentage of area expressing GRPR and the number of cells expressing PSMA were close to reaching significance at the 0.05 level. MDS provided a map of the overall, independent association confirming that GRPR and PSMA represent inversely correlated measures of the same dimension. In conclusion, our data showed that GRPR expression should be evaluated in prostate biopsy specimens to improve our ability to detect PC with low grades at the earliest phases of development. Considering that GRPRs appear to be directly involved in the mechanisms of tumor proliferation, advancements in nuclear medicine radiotherapy can focus on this receptor to improve the therapeutic approach to PC. Further studies in our laboratory will investigate the molecular mechanisms of activation based on GRPR.

An extended regulatory landscape drives Tbx18 activity in a variety of prostate-associated cell lineages

The evolutionarily conserved transcription factor, Tbx18, is expressed in a dynamic pattern throughout embryonic and early postnatal life and plays crucial roles in the development of multiple organ systems. Previous studies have indicated that this dynamic function is controlled by an expansive regulatory structure, extending far upstream and downstream of the gene. With the goal of identifying elements that interact with the Tbx18 promoter in developing prostate, we coupled chromatin conformation capture (4C) and ATAC-seq from embryonic day 18.5 (E18.5) mouse urogenital sinus (UGS), where Tbx18 is highly expressed. The data revealed dozens of active chromatin elements distributed throughout a 1.5 million base pair topologically associating domain (TAD). To identify cell types contributing to this chromatin signal, we used lineage tracing methods with a Tbx18 Cre "knock-in" allele; these data show clearly that Tbx18-expressing precursors differentiate into wide array of cell types in multiple tissue compartments, most of which have not been previously reported. We also used a 209 kb Cre-expressing Tbx18 transgene, to partition enhancers for specific precursor types into two rough spatial domains. Within this central 209 kb compartment, we identified ECR1, previously described to regulate Tbx18 expression in ureter, as an active regulator of UGS expression. Together these data define the diverse fates of Tbx18+ precursors in prostate-associated tissues for the first time, and identify a highly active TAD controlling the gene's essential function in this tissue.

Generation and Regulation of Spontaneous Contractions in the Prostate

Spontaneous myogenic contractions have been shown to be significantly upregulated in prostate tissue collected from men with Benign Prostatic Hyperplasia (BPH), an extremely common disorder of the ageing male. Although originally thought likely to be involved in 'housekeeping' functions, mixing prostatic secretions to prevent stagnation, these spontaneous myogenic contractions provide a novel opportunity to understand and treat BPH. This treatment potential differs from previous models, which focused exclusively on attenuating nerve-mediated neurogenic contractions. Previous studies in the rodent prostate have provided an insight into the mechanisms underlying the regulation of myogenic contractions. 'Prostatic Interstitial Cells' (PICs) within the prostate appear to generate pacemaker potentials, which arise from the summation of number of spontaneous transient depolarisations triggered by the spontaneous release of Ca²⁺ from internal stores and the opening of Ca²⁺-activated Cl^- channels. Pacemaker potentials then conduct into neighbouring smooth muscle cells to generate spontaneous slow waves. These slow waves trigger the firing of 'spike-like' action potentials, Ca²⁺ entry and contraction, which are not attenuated by blockers of neurotransmission. However, these spontaneous prostatic contractions can be modulated by the autonomic nervous system. Here, we discuss the mechanisms underlying rodent and human prostate myogenic contractions and the actions of existing and novel pharmacotherapies for the treatment of BPH. Understanding the generation of human prostatic smooth muscle tone will confirm the mechanism of action of existing drugs, inform the identification and effectiveness of new pharmacotherapies, as well as predict patient outcomes.

Somatostatin receptor subtype 1 as a potential diagnostic marker and therapeutic target in prostate cancer

BACKGROUND

Prostate cancer (PCa) is a highly prevalent neoplasia that is strongly influenced by the endocrine system. Somatostatin (SST) and its five receptors (sst1-5 encoded by SSTR1-5 genes) comprise a pleiotropic system present in most endocrine-related cancers, some of which are successfully treated with SST analogs. Interestingly, it has been reported that SSTR1 is overexpressed in PCa, but its regulation, functional role, and clinical implications are still poorly known.

METHODS

PCa specimens (n = 52) from biopsies and control prostates from cystoprostatectomies (n = 12), as well as in silico databases were used to evaluate SSTR1 and miRNAs expression. In vitro studies in 22Rv1 PCa cells were implemented to explore the regulation of SSTR1/sst1 by different miRNAs, and to evaluate the consequences of SSTR1/sst1 overexpression, silencing and/or activation [with the specific BIM-23926 sst1 agonist (IPSEN)] on cell-proliferation, migration, signaling-pathways, and androgen-signaling.

RESULTS

We found that SSTR1 is overexpressed in multiple cohorts of PCa samples, as compared with normal prostate tissues, wherein it correlates with androgen receptor (AR) expression, and appears to be associated with aggressiveness (metastasis). Furthermore, our data revealed that SSTR1/sst1 expression might be regulated by specific miRNAs in PCa, including miR-24, which is downregulated in PCa samples and correlates inversely with SSTR1 expression. In vitro studies indicated that treatment with the BIM-23926 sst1 agonist, as well as SSTR1 overexpression, decreased, whereas SSTR1 silencing increased, cell-proliferation in 22Rv1 cells, likely through the regulation of PI3K/AKT-CCND3 signaling-pathway. Importantly, sst1 action was also able to modulate androgen/AR activity, and reduced PSA secretion from PCa cell lines.

CONCLUSIONS

Altogether, our results indicate that SSTR1 is overexpressed in PCa, where it can exert a relevant pathophysiological role by decreasing cell-proliferation and PSA secretion. Therefore, sst1, possibly in combination with miR-24, could be used as a novel tool to explore therapeutic targets in PCa.

New intraprostatic injectables and prostatic urethral lift for male LUTS

Treatment modalities for male lower urinary tract symptoms (LUTS) comprise a broad spectrum of medical and surgical options. Interest is growing in minimally invasive treatment options, which should ideally be performed in an outpatient setting and have a short recovery time, durable efficacy and a good safety profile. The preservation of all aspects of sexual function, including antegrade ejaculation, seems to be increasingly important for patients. Initial experimental data on new minimally invasive procedures-such as the intraprostatic injection of novel agents including botulinum neurotoxin A (BoNT-A), NX-1207 and PRX302-were promising, but clinical trials have not confirmed the findings. Trials of the mechanical prostatic urethral lift device-Urolift(®) (Neotract, Inc., USA)-have been positive, but further long-term results are needed to confirm its beneficial effects.

Malignant cell-derived extracellular vesicles express different chromogranin epitopes compared to prostasomes

BACKGROUND

Prostasomes are nanosized extracellular vesicles exocytosed by prostate epithelial cells. They have been assigned many roles propitious to sperm in favor of fertilization. Prostatic cancer cells can also produce and secrete extracellular vesicles.

METHODS

We assessed using ELISA, the surface expression of chromogranin proproteins on prostasomes and malignant extracellular vesicles of four different prostate cancer cell-lines, two hormone sensitive and two hormone refractory. We used a panel of chromogranin A and chromogranin B antibodies against peptides in-between hypothetical cleavage sites along the proproteins.

RESULTS

A diverging pattern of chromogranin peptides was apparent when comparing prostasomes and malignant extracellular vesicles indicating a phenotypical change. We also compared western blot patterns (prostasomes and malignant extracellular vesicles) for selected antibodies that displayed high absorbances in the ELISA. Western blot analyses revealed various cleavage patterns of those proproteins that were analyzed in prostasomes and extracellular vesicles.

CONCLUSION

Chromogranins are constituents of not only prostasomes but also of malignant prostate cell-derived extracellular vesicles with different amino acid sequences exposed at the membrane surface giving rise to a mosaic pattern. These findings may be of relevance for designing new assays for detection or even possible treatment of prostate cancers.

Alteration of loperamide-induced prostate relaxation in high-fat diet-fed rats

OBJECTIVE

To investigate the change of loperamide-induced prostate relaxation in rats fed with high-fat diet (HFD).

MATERIALS AND METHODS

Adult male Wistar rats were divided into 2 groups: (1) control rats fed with normal chow and (2) rats fed with HFD for 6 months. The prostate was removed for histology study. Isolated prostate strips were hung in organ bath and precontracted with 1 μmol/L phenylephrine or 50 mmol/L KCl. The relaxation responses to loperamide 0.1 to 10 μmol/L were recorded. Western blotting analyses were performed for prostate μ-opioid receptors (MOR) and ATP-sensitive potassium (K(ATP)) channel proteins: sulfonylurea receptor (SUR) and inwardly rectifying potassium channel (Kir) 6.2 subunits.

RESULTS

Body weight, prostate weight, plasma levels of glucose, insulin, triglyceride, and cholesterol, as well as systolic blood pressure, were significantly increased in the HFD rats. Histology showed prostatic hyperplasia in the HFD rat prostate. Prostatic relaxation induced by loperamide was markedly reduced in HFD when compared to the control. Protein expressions of MOR, SUR, and Kir 6.2 were decreased in HFD-fed rats.

CONCLUSION

Loperamide-induced prostate relaxation is decreased in HFD rats due to reduced MOR and K(ATP) channel expressions.

Expression and function of gastrin-releasing peptide (GRP) in normal and cancerous urological tissues

Gastrin-releasing peptide (GRP) acts as an important regulatory peptide in several normal physiological processes and as a growth factor in certain cancers. In this review we provide a comprehensive overview of the current state of knowledge of GRP in urological tissues under both normal and cancerous conditions. GRP and its receptor, GRP-R, are expressed in the normal kidney and renal cancers. GRP can stimulate the growth of renal cancer cells. GRP and GRP-R are expressed in prostate cancer and GRP can stimulate the growth of prostate cancer cell lines. Importantly, GRP is a key neuroendocrine peptide, which may be involved in the progression of advanced prostate cancer and in the neuroendocrine differentiation of prostate cancer. Recent animal studies have shown that GRP and GRP-R are an integral part of male sexual function and play a crucial role in spinal control of erections and ejaculation.

Stereological Quantification of Nerve Fibers Immunoreactive to PGP 9.5, NPY, and VIP in Rat Prostate During Postnatal Development

This work was undertaken to study prostate innervation during the postnatal development of rats. It deals with the quantification of nervous fibers throughout all the regions of the rat prostate during the postnatal development using a general marker for nervous tissue, protein gene product 9.5, and 2 neuropeptides (NPY and VIP). Forty male Wistar rats (prepubertals, pubertals, young, and aged adults) were studied for immunohistochemistry of protein gene product (PGP 9.5), neuropeptide Y (NPY), and vasoactive intestinal polypeptide (VIP). They were also evaluated for length density of nerve fibers (L(V) PGP 9.5, L(V) NPY, L(V) VIP). Nerve fibers immunoreactive to the 3 antigens studied were detected in all the groups and in all the prostate zones. Periductal L(V) NPY evidenced a significant increase in the pubertal group, maintained throughout adult life. Periductal L(V) VIP showed a significant increase in young adults. The length densities of VIP and NPY fibers were significantly higher in periductal and ampular locations in comparison with dorsal and ventral sites. It can be concluded that the relative amount of nerve fibers in rat prostate, detected by PGP 9.5, does not change during postnatal development. There were significant changes in NPY and VIP fibers, showing an increase in periurethral ducts at puberty. The abundance of peptidergic innervation around the excretory ducts is related to their contractility. The development of innervation of periurethral ducts is regulated by androgens.

Transdifferentiation of cultured human prostate cancer cells to a neuroendocrine cell phenotype in a hormone-depleted medium

Neuroendocrine (NE) cells are enigmatically found in association with human prostate cancers and their numbers are reported to increase in advanced and hormoneresistant tumors. The origin of this cell type and the reason for their appearance in prostate tumors remains unresolved. Previously, Bang et al. (Proc Natl Acad Sci USA 1994;91:5330) reported that dibutyryl adenosine 3',5'-cyclic phosphate (db-cAMP), an agent that upregulates intracellular cAMP, was able to induce a NE cell-like phenotype of cultured human prostate cancer cells, including the androgen-sensitive LNCaP line. Here we report that chronic incubation of LNCaP cells in a medium containing 10% charcoal-stripped fetal bovine serum (CSFBS) likewise induces NE differentiation of these cells. Within 5 days of switching low density cultures of LNCaP cells to this modified medium, the cells growth arrest and acquire an altered morphology with numerous cytoplasmic secretory granules and elongated processes that resemble cultured neurons. This morphology predominates at 10 days with complete transformation seen by 20 days of culture. Electron microscopic analysis of sections of CS-FBS maintained cells showed the presence of abundant dense core secretory granules characteristic of NE cells. Immunohistochemical staining identified the upregulation of the expression of NE markers bombesin, neuron-specific enolase, and S-100 in this modified culture medium. Once established, the NE cell-like phenotype was found to be reversible upon replacement with a medium containing unmodified fetal bovine serum, but not by direct supplementation of CS-FBS medium with dihydrotestosterone (DHT) (I nM). DHT supplementation did, however, suppress the development of the NE cell-like phenotype when it was present at the initiation of exposure to CS-FBS medium. In contrast to db-cAMP treatment, which did not affect prostate specific antigen (PSA) or androgen receptor (AR) expression of LNCaP cells, NE-differentiated LNCaP cells derived in this hormone-deficient medium showed marked downregulation of PSA and AR expression. These in vitro results further support the concept that prostate cancer cells can tranform in vivo to cells with a NE phenotype and suggest that this transformation might be accelerated in patients by certain therapies for prostate cancer.

Botulinum toxin injection for lower urinary tract dysfunction

Botulinum toxin has been recently accepted as a novel treatment for lower urinary tract dysfunctions refractory to conventional treatment. Review of the clinical trials in recent years, botulinum toxin type A has been widely used in the urethra or urinary bladder to treat voiding dysfunction due to detrusor sphincter dyssynergia, incontinence due to neurogenic or idiopathic detrusor overactivity, sensory disorders such as bladder hypersensitivity, overactive bladder, and interstitial cystitis/painful bladder syndrome. Intravesical botulinum toxin type A injection is effective in treatment of urinary incontinence due to detrusor overactivity in men and women, as well as in children. Currently botulinum toxin type A has also been applied to treat lower urinary tract symptoms due to benign prostatic hyperplasia in patients not suitable for surgery. This article reviewed the recent advances of botulinum toxin type A on lower urinary tract dysfunction.

Multiple cellular responses to serotonin contribute to epithelial homeostasis

Epithelial homeostasis incorporates the paradoxical concept of internal change (epithelial turnover) enabling the maintenance of anatomical status quo. Epithelial cell differentiation and cell loss (cell shedding and apoptosis) form important components of epithelial turnover. Although the mechanisms of cell loss are being uncovered the crucial triggers that modulate epithelial turnover through regulation of cell loss remain undetermined. Serotonin is emerging as a common autocrine-paracine regulator in epithelia of multiple organs, including the breast. Here we address whether serotonin affects epithelial turnover. Specifically, serotonin's roles in regulating cell shedding, apoptosis and barrier function of the epithelium. Using in vivo studies in mouse and a robust model of differentiated human mammary duct epithelium (MCF10A), we show that serotonin induces mammary epithelial cell shedding and disrupts tight junctions in a reversible manner. However, upon sustained exposure, serotonin induces apoptosis in the replenishing cell population, causing irreversible changes to the epithelial membrane. The staggered nature of these events induced by serotonin slowly shifts the balance in the epithelium from reversible to irreversible. These finding have very important implications towards our ability to control epithelial regeneration and thus address pathologies of aberrant epithelial turnover, which range from degenerative disorders (e.g.; pancreatitis and thyrioditis) to proliferative disorders (e.g.; mastitis, ductal ectasia, cholangiopathies and epithelial cancers).

Changes in the number and volume of NPY and VIP neurons from periprostatic accessory vegetative ganglia in pre- and peripubertal rats. A stereological study

The amount of neurons of periprostatic accessory ganglia in pre- and peripubertal rats was studied to ascertain whether the development of these autonomic ganglia is androgen-dependent. Stereological estimates of the volumes and number of neurons immunoreactive to protein gene product 9.5 (PGP 9.5), neuropeptide Y (NPY), and vasoactive intestinal polypeptide (VIP) were carried out. Immunostaining of androgen receptors (AR) in the ganglia was also performed. The ganglionic neurons from the two groups studied were immunoreactive to PGP 9.5, NPY, and VIP. Almost all the neurons were immunostained for AR. The ganglionic volume showed a significant increase in peripubertal prostate in comparison with the prepubertal gland. No significant changes were observed with respect to the absolute number of neurons immunoreactive to all the antigens. The neuronal volume was significantly increased in peripubertal rats in comparison with prepubertal animals. These findings led us to the following conclusions: There is no evidence of neurogenesis during pubertal development in the periprostatic accessory ganglia of the rat. The increase of ganglionic volume in puberty is due to the growth in neuronal volume. There were no differences between the sizes of NPY and VIP neurons in pubertal periprostatic accessory ganglia. The development of periprostatic vegetative neurons is androgen-dependent.

Therapeutic effects of add-on botulinum toxin A on patients with large benign prostatic hyperplasia and unsatisfactory response to combined medical therapy

OBJECTIVE

Botulinum toxin A (BoNT-A) injections into the prostate have been reported to be effective and durable in the treatment of small benign prostatic hyperplasia (BPH). This study evaluated the effectiveness of BoNT-A in patients with large BPH with an unsatisfactory response to combined alpha-blocker and 5-alpha-reductase inhibitor therapy.

MATERIAL AND METHODS

Sixty patients with BPH and total prostate volume (TPV) of > 60 ml with unsatisfactory response to combination medical therapy were randomly assigned to receive add-on intraprostatic BoNT-A injection (n=30) or continued medical therapy (control group). Patients in the treatment group received 200-600 U of Botox injected into the prostate. Outcome parameters including International Prostate Symptom Score (IPSS), quality of life index (QoL-I), TPV, maximum flow rate (Q(max)) and postvoid residual (PVR) were compared between treatment and control groups at baseline, 6 months and 12 months.

RESULTS

Significant decreases in IPSS, QoL-I and TPV, and increase in Q(max) were observed at 6 months and remained stable at 12 months in the treatment group. Improvements in IPSS and QoL-I were also observed at 6 months and a decrease in TPV at 12 months was noted in the control group. However, no significant changes in any parameters except for QoL-I at 6 and 12 months were noted between the treatment and control groups. Acute urinary retention developed in three patients receiving BoNT-A treatment. Three BoNT-A and two medical treatment patients converted to transurethral surgery at the end of study.

CONCLUSIONS

This study shows that add-on prostatic BoNT-A medical treatment can reduce prostate volume and improve lower urinary tract symptom score and QoL-I within 6 months in the treatment of large BPH. However, the therapeutic effect at 12 months was similar to combination medical treatment.

Relief by botulinum toxin of lower urinary tract symptoms owing to benign prostatic hyperplasia: early and long-term results

OBJECTIVES

To present a comprehensive experience with intraprostatic botulinum toxin (BT) injection in men with symptomatic benign prostatic hyperplasia (BPH).

METHODS

In this open-label study using an outpatient setting, 77 men with BPH received 200 intraprostatic BT A units (Botox) using an ultrasound-guided transperineal approach. We evaluated the American Urological Association (AUA) score, serum prostate-specific antigen (PSA), prostatic volume, residual volume, and peak urinary flow rates. The primary endpoint was symptomatic improvement after treatment, as measured by means of AUA score and peak urinary flow rates. The secondary endpoint was the evaluation of prostatic volume, serum PSA, and residual urinary volume.

RESULTS

No significant local effects occurred. At their 1-month evaluation, 41 patients had subjective symptomatic relief. Compared with baseline values, AUA score was reduced from 24.1 +/- 4.6 to 12.6 +/- 2.9 (P = .00001), and serum PSA from 6.2 +/- 1.7 to 4.8 +/- 1.0 ng/mL (P = .03). At the same time, prostatic volume and residual urine volume were reduced by 12.7% and 12.8%, respectively, and mean peak urinary flow rate increased (P = .01). At 2 months' evaluation, 55 patients had subjective symptomatic relief. AUA score was reduced by 63.9% (P = .00001) compared with baseline values. In the same patients, serum PSA, prostatic volume, and residual urine volume were reduced by 51.6% (P = .00001), 42.8% (P = .00001), and 55.9% (P = .002), respectively, and mean peak urinary flow rate increased significantly.

CONCLUSIONS

Intraprostatic BT seems to be a promising approach to the treatment of BPH. It is safe, effective, well-tolerated, and not related to the patient's willingness to complete treatment.

Adrenomedullin, an autocrine/paracrine factor induced by androgen withdrawal, stimulates 'neuroendocrine phenotype' in LNCaP prostate tumor cells

Neuroendocrine (NE) differentiation in prostate cancer (CaP) has been reported to be an early marker associated with the development of androgen independence. The mechanisms by which CaP acquires NE properties are poorly understood. In this study, a putative role of adrenomedullin (AM) in the NE differentiation was investigated. The expression of AM and AM receptors (calcitonin receptor-like receptor (CRLR)/receptor activity modifying protein-2 and -3 (RAMP2 and RAMP3) was evaluated after experimental manipulation of androgen status. Levels of AM mRNA and immunoreactive AM (ir-AM) increased four- to sevenfold in androgen-sensitive LNCaP cells after androgen withdrawal in vitro and in LNCaP xenografts in animals after castration. Treatment of LNCaP cells with androgen analogue (dihydrotestosterone; 10(-9) M) prevented the increase in AM mRNA and ir-AM levels. Interestingly, the expression of CRLR, RAMP2 and RAMP3 is not regulated by androgen status. We demonstrate that in the presence of serum, AM is able to induce an NE phenotype in LNCaP cells via CRLR/RAMP2 and RAMP3, which includes extension of neuritic processes and expression of the neuron-specific enolase (NSE), producing cGMP in a dose-dependent manner, which is mediated by a pertussis toxin-sensitive GTP-binding protein. 8-Bromo-cGMP mimicked the effects of AM on cell differentiation. We demonstrate that AM induces a G-kinase Ialpha translocation to the nucleus. The protein kinase G inhibitor KT-5823 inhibited the neurite outgrowth induced by both AM and 8-bromo-cGMP. In noncastrated animals, administration of AM enhanced expression of NSE and chromogranin A in LNCaP xenografts with a significant increase of NSE levels in serum and no changes in tumor growth. In castrated animals, intraperitoneal injection of AM resulted in a 240+/-18% (P<0.001) increase in tumor volume 36 days after treatment, indicating that the nature of effect of AM in CaP depends on the presence or absence of endogenous androgen. Together, these results demonstrate that AM may function as a mediator of NE-like differentiation in culture as well as in vivo and indicate that its production may be important for tumor resurgence following androgen ablation.

A study of the prostate, androgens and sexual activity of male rats

BACKGROUND

The prostate is a sexual gland that produces important substances for the potency of sperm to fertilize eggs within the female reproductive tract, and is under complex endocrine control. Taking advantage of the peculiar behavioral pattern of copulating male rats, we developed experimental paradigms to determine the influence of sexual behavior on the level of serum testosterone, prostate androgen receptors, and mRNA for androgen receptors in male rats displaying up to four consecutive ejaculations.

METHODS

The effect of four consecutive ejaculations was investigated by determining levels of (i) testosterone in serum by solid phase RIA, (ii) androgen receptors at the ventral prostate with Western Blots, and (iii) androgen receptors-mRNA with RT-PCR. Data were analyzed with a one-way ANOVA followed by a post hoc application of Dunnett's test if required.

RESULTS

The constant execution of sexual behavior did not produce any change in the weight of the ventral prostate. Serum testosterone increased after the second ejaculation, and remained elevated even after four ejaculations. The androgen receptor at the ventral prostate was higher after the first to third ejaculations, but returned suddenly to baseline levels after the fourth ejaculation. The level of mRNA increased after the first ejaculation, continued to increase after the second, and reached the highest peak after the third ejaculation; however, it returned suddenly to baseline levels after the fourth ejaculation.

CONCLUSION

Four consecutive ejaculations by sexually experienced male rats had important effects on the physiological responses of the ventral prostate. Fast responses were induced as a result of sexual behavior that involved an increase and decrease in androgen receptors after one and four ejaculations, respectively. However, a progressive response was observed in the elevation of mRNA for androgen receptors, which also showed a fast decrease after four ejaculations. All of these changes with the prostate gland occurred in the presence of a sustained elevation of testosterone in the serum that started after two ejaculations. A consideration of these fast-induced changes suggests that the nerve supply plays a key role in prostate physiology during the sexual behavior of male rats.

Intermittent hormone therapy in nonmetastatic prostate cancer

PURPOSE

The object of this study was to evaluate the duration of response to intermittent androgen deprivation (IAD) in patients with nonmetastatic recurrent or localized prostate cancer.

PATIENTS AND METHODS

One hundred ten patients received IAD from February 1992 to February 2005. One hundred three patients were treated after failure of primary radiation therapy and/or prostatectomy, with the remaining 7 patients treated primarily with IAD. The median duration of treatment cycle was 6 months. Patients were considered resistant to hormone therapy if the prostate-specific antigen (PSA) level increased, with castrate levels of testosterone. At the time of initial diagnosis, the median Gleason score was 7 (range, 4-9), and tumor stages were as follows: T1/T2 (n = 73), T3 and T4 N1 (n = 34), and other (n = 3). The median PSA at the initiation of IAD was 8.25 ng/mL.

RESULTS

The median follow-up after beginning IAD was 45.5 months. Patients received a median of 2 cycles (range, 1-9 cycles). Ninety-four of 110 patients (85.5%) remained responsive to IAD. Sixteen patients (14.5%) progressed to become refractory to primary hormone treatment. Patients with a higher tumor stage (T3 and T4) were significantly more likely to develop resistance. The median time to become refractory to hormone therapy was 47.9 months (range, 9.4-93.4 months). Five patients were put on secondary continuous hormone treatment, and 3 of them developed resistance at a median of 9 months. One patient was put on a secondary IAD and was still responding at the last follow-up.

CONCLUSION

With 85.5% of the original patient population still responding to the primary hormone therapy at 45.5 months of follow-up, IAD appears to be a viable option for patients with biochemical failure after local radiation therapy. A pattern of shortening time between cycles and an increasing nadir PSA level with each successive cycle is consistent with the gradual development of hormone resistance.

Effect of Prolactin and Bromocriptine on the Population of Prostate Neuroendocrine Cells from Intact and Cyproterone Acetate-Treated Rats: Stereological and Immunohistochemical Study

This work deals with the quantification of serotonin-immunoreactive prostate neuroendocrine cells (NECs) in rats exposed to prolactin in normal, cyproterone acetate-exposed, and bromocriptine-exposed animals to establish the possible influence of prolactin with or without androgenic blockade on this cell population. Thirty male peripubertal Sprague-Dawley rats were grouped as controls (CT) and those treated with cyproterone acetate (CA), cyproterone acetate plus prolactin, cyproterone acetate plus bromocriptine, prolactin (PL), and bromocriptine (BC). The volume of ductal epithelium (Vep) and total number (NSER) of the NECs serotonin-immunoreactive were measured. NECs were detected in the periurethral ducts. Compared to CT, Vep was increased in PL and BC and NSER was decreased in CA and increased in the prolactin or bromocriptine groups. The androgenic blockade decreases NSER in rat prostate; PL induces in normal and cyproterone acetate-treated rats the increase of NSER; and BC exerts a local effect over the prostate similar to that described for PL.

Botulinum toxin type A improves benign prostatic hyperplasia symptoms in patients with small prostates

OBJECTIVES

To expand the clinical use of botulinum toxin A (BTX-A) in treating patients with small prostates and symptomatic benign prostatic hyperplasia (BPH). BTX-A injection into the prostate in patients with voiding dysfunction and large prostates has been reported.

METHODS

Sixteen men with symptomatic BPH, a prostate volume less than 30 cm3, peak flow rate less than 12 mL/s, and with refractory disease after at least 1 month of alpha-blocker treatment received BTX-A 100 U injection into the prostate transperineally under transrectal ultrasound guidance. The clinical effects were evaluated at baseline and after treatment.

RESULTS

No significant local or systemic side effects were observed in any of the patients. All patients reported subjective improvement starting at approximately 1 week and achieved a maximal effect after 1 month that was maintained at 3 and 6 months. At 6 to 12 months (mean 10) of follow-up, no patient had symptom recurrence. The mean prostate volume, symptom score, and quality-of-life index were significantly reduced by 13.3% (from 19.6 +/- 1.2 to 17.0 +/- 1.1 cm3), 52.6% (from 18.8 +/- 1.6 to 8.9 +/- 1.9), and 44.7% (from 3.8 +/- 0.3 to 2.1 +/- 0.3), respectively. The maximal flow rate increased significantly by 39.8% (from 7.3 +/- 0.7 to 11.8 +/- 0.8 mL/s). In 2 patients who underwent biopsy 1 month after BTX-A injection, terminal deoxynucleotidyl-mediated deoxyuridine triphosphate nick end labeling staining demonstrated an increase in apoptotic activity, not only in the glandular component, but also in the stromal component of the prostatic tissue.

CONCLUSIONS

BTX-A injected into the prostate is a promising treatment for patients with small prostates and symptomatic BPH.

Vasoactive intestinal peptide induces neuroendocrine differentiation in the LNCaP prostate cancer cell line through PKA, ERK, and PI3K

BACKGROUND

Neuroendocrine (NE) differentiation in prostate cancer has been correlated with unfavorable clinical outcome. The mechanisms by which prostate cancer acquires NE properties are poorly understood, but several signaling pathways have been proposed. We have previously observed that vasoactive intestinal peptide (VIP) stimulates cAMP production mainly through VPAC(1) receptor, inducing NE differentiation in LNCaP cells. The aim of this study was to analyze the mechanisms involved in this process.

METHODS

Reverse transcriptase (RT)-polymerase chain reaction (PCR), quantitative real-time RT-PCR, Western blotting, and immunocytochemistry were performed.

RESULTS

LNCaP cells produce VIP, as demonstrated by RT-PCR and immunocytochemistry. VIP induced NE differentiation of LNCaP cells at a time as short as 1 hr of treatment, and the same occurred with the expression and secretion of neuronal-specific enolase (NSE, a NE differentiation marker). These effects were faster than those exerted by serum-deprivation. VIP induced extracellular signal-regulated kinase 1 and 2 (ERK1/2) phosphorylation and NE differentiation by PKA-dependent and independent pathways, since the PKA inhibitor H89 partially blocked VIP-induced NE differentiation and did not affect ERK1/2 phosphorylation. mitogen-activated protein kinase kinase (MEK) and phosphoinositide 3-kinase (PI3K) appear to be also involved since the inhibitors PD98059 and wortmannin abolished ERK1/2 phosphorylation and decreased NE differentiation induced by VIP. Moreover, VIP activated Ras suggesting the involvement of a Ras-dependent pathway.

CONCLUSIONS

VIP behaves as autocrine/paracrine factor in LNCaP cells by inducing NE differentiation through PKA, ERK1/2, and PI3K.

Constitutive activation of gp130 leads to neuroendocrine differentiation in vitro and in vivo

BACKGROUND

Neuroendocrine (NE) differentiation in prostate tumors has been correlated with androgen independent disease and increased risk of death. In vitro, IL-6 initiates NE differentiation utilizing the signal transduction initiated by the interaction with IL-6R alpha and gp130. In this study we analysed the NE differentiation process in vitro and in vivo using the LNCaP androgen dependent cell line via ligand independent induction of NE differentiation.

METHODS

LNCaP cells were transfected with a constitutively active gp130 subunit, gp130act. Cell proliferation rate was determined and clones were examined for neuroendocrine differentiation by morphological change, upregulation of CgA and serotonin and formation of dense core vesicles with LNCaP parental cells as the control. Xenograft formation was examined and compared in immunocompromised mice.

RESULTS

Gp130act expression promoted significant neuroendocrine differentiation in vitro as determined by a NE like morphology change (increased neurite like extension formation), elevated CgA expression and the formation of dense core vesicles (DCV). These measures concurred with those examined in LNCaP cells following 100 ng/ml IL-6 treatment. Further investigation of the LNCaP gp130act cells in vivo, in immunocompromised androgen intact mice, confirmed that the NE like morphology, as determined by histological and high resolution transmission electron microscopy, was maintained.

CONCLUSIONS

NE differentiation was initiated by the expression of gp130act in a ligand independent manner, highlighting the importance of gp130 in the neuroendocrine differentiation process. Further investigation of upregulated/downregulated gene expression in these cells may provide valuable insight into the NE differentiation process.

Characterization of prostatic neuroendocrine cell line established from neuroendocrine carcinoma of transgenic mouse allograft model

BACKGROUND

The role of neuroendocrine (NE) cells in prostate cancer remains unclear. A useful model is necessary to study the biology of NE cells. We herein describe the establishment and characterization of an immortalized cell line from an NE-10 allograft of murine prostatic NE carcinoma.

METHODS

A novel cell line, designated NE-CS, was developed from an NE-10 allograft that was established from the ventral prostate of the LPB-T-antigen (Tag) transgenic mouse, line 10 (12T-10). We investigated the growth, karyotype, electron microscopic findings, expression of Tag and androgen receptor (AR), and tumorigenesis of the cells in athymic mice.

RESULTS

The immortal cell line NE-CS was maintained in vitro for more than 2 years. The NE-CS cells had dendritic-like extensions with dense core granules in the cytoplasm and produced serotonin and somatostatin in conditioned medium. The cells expressed neither Tag nor AR. They showed androgen-independent growth in vitro and a hypotetraploid karyotype similar to the original NE-10 allograft. The NE-CS cells, which were subcutaneously inoculated into athymic mice, formed tumors with the NE phenotype. The tumors exhibited accelerated growth compared to the original NE-10 allograft.

CONCLUSIONS

The established cell line has characteristics of NE differentiation and tumorigenic ability. This cell line may be a promising model to understand the molecular mechanisms associated with the acquisition of hormone refractory prostate cancer.

NE-10 neuroendocrine cancer promotes the LNCaP xenograft growth in castrated mice

Increases in neuroendocrine (NE) cells and their secretory products are closely correlated with tumor progression and androgen-independent prostate cancer. However, the mechanisms by which NE cells influence prostate cancer growth and progression, especially after androgen ablation therapy, are poorly understood. To investigate the role of NE cells on prostate cancer growth, LNCaP xenograft tumors were implanted into nude mice. After the LNCaP tumors were established, the NE mouse prostate allograft (NE-10) was implanted on the opposite flank of these nude mice to test whether NE tumor-derived systemic factors can influence LNCaP growth. Mice bearing LNCaP tumors with or without NE allografts were castrated 2 weeks after NE tumor inoculation, and changes in LNCaP tumor growth rate and gene expression were investigated. After castration, LNCaP tumor growth decreased in mice bearing LNCaP tumors alone, and this was accompanied by a loss of nuclear androgen receptor (AR) localization. In contrast, in castrated mice bearing both LNCaP and NE-10 tumors, LNCaP tumors continued to grow, had increased levels of nuclear AR, and secreted prostate-specific antigen. Therefore, in the absence of testicular androgens, NE secretions were sufficient to maintain LNCaP cell growth and androgen-regulated gene expression in vivo. Furthermore, in vitro experiments showed that NE secretions combined with low levels of androgens activated the AR, an effect that was blocked by the antiandrogen bicalutamide. Because an increase in AR level has been reported to be sufficient to account for hormone refractory prostate cancers, the NE cell population ability to increase AR level/activity can be another mechanism that allows prostate cancer to escape androgen ablation therapy.

Metastatic prostate cancer with normal level of serum prostate-specific antigen

The clinical and pathological features of metastatic prostate cancer with normal level of serum prostate-specific antigen (PSA) were investigated. Four patients with metastatic prostate cancer had serum PSA within the normal range at the diagnosis. All tumors were poorly-differentiated adenocarcinoma. Endocrine therapy was performed as the initial therapy in all patients. Despite subsequently treatment, all cases died of prostate cancer at 2, 8, 9 and 38 months. During disease progression, 3 of 4 patients had elevated serum markers such as carcinoembryonic antigen (CEA), CA19-9, CA15-3, CA125, neuron-specific enolase and pro-gastrin releasing peptide. Immunohistochemical examination of the initial biopsy specimens revealed that 4 and 3 cases were positive for CEA and chromogranin A, respectively. In advanced prostate cancer patients with low PSA level, those markers may aid in the follow up of disease.

The opioid agonist ethylketocyclazocine reverts the rapid, non-genomic effects of membrane testosterone receptors in the human prostate LNCaP cell line

Neuropeptides influence cancer cell replication and growth. Opioid peptides, and opiergic neurons are found in the prostate gland, and they are proposed to exert a role in tumor regulation, influencing cancer cell growth, as opioid agonists inhibit cell growth in several systems, including the human prostate cancer cell line LNCaP. In the same cell line, the existence of membrane testosterone receptors was recently reported, which increase, in a non-genomic manner, the secretion of PSA, and modify actin cytoskeleton dynamics, through the signaling cascade FAK-->PI-3 kinase-->Cdc42/Rac1. In the present work, we present data supporting that the general opioid agonist Ethylketocyclazocine (EKC) decreases testosterone-BSA (a non-internalizable testosterone analog) induced PSA secretion. Furthermore, we report that this opioid affects this non-genomic testosterone action, by modifying the distribution of the actin cytoskeleton in the cells, disrupting the above signaling cascade. In addition, after long (>24 h) incubation, opioids decrease the number of membrane testosterone receptors, and reverse their effect on the signaling molecules. In conclusion, our results provide some new insights of a possible action of opioids in prostate cancer control by interfering with the action and the expression of membrane testosterone receptors and signaling.

Cell specific expression of CD10/neutral endopeptidase 24.11 gene in human prostatic tissue and cells

BACKGROUND

Neutral endopeptidase (NEP/CD10) is a cell surface zinc metalloproteinase that functions as part of a regulatory loop controlling local concentrations of peptide substrates and associated peptide-mediated signal transduction processes. In contrast to the encouraging data dealing with NEP activity and regulation in prostate epithelial cells, only a few studies are available on the cellular expression and localization of neutral endopeptidase in the prostatic stromal and cancer cells. Here, we describe the cellular localization of NEP in human prostatic tissue and cells using in situ RT-PCR as a novel molecular biological approach.

METHODS

Immunofluorescence and Western blot experiments were performed to control the expression and distribution of the NEP in normal and malignant human prostatic tissues and cell lines. NEP gene expression was monitored by RT-PCR, NEP mRNA was detected in paraffin tissue sections and cultured cells of human prostate by the highly sensitive method of one step-in situ reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

NEP mRNA was detected in human prostatic tissue and in cultured cells by means of in situ RT-PCR. Prostatic tissue showed strong signals in the glandular epithelium and weak signals in the stroma, cultured cells displayed strong signals in prostate cancer cells (LNCaP) and weak signals in stromal cells (hPCPs). Western blot experiments were performed using whole cell extracts to proof the presence of NEP protein in LNCaP and hPCPs. The experiments confirm the expression of NEP by both cell types, however, the experiment with hPCPs cells showed two bands. NEP-immunofluorescence was strong in normal prostatic epithelium and confined to the apical plasma membrane. In dedifferentiated prostate cancer specimens, immunofluorescence of apical plasma membranes was lost, and both the cytoplasm and portions of the plasma membrane were immunoreactive for NEP. Prostate cancer cells (LNCaP) showed a strong immunoreaction of the plasma membrane and the cytoplasm. In comparison with LNCaP cells, only a weak cytoplasmic immunofluorescence was found in some stromal cells (hPCPs).

CONCLUSIONS

In normal prostatic tissue and specimens derived from human prostate cancer, NEP mRNA and protein are expressed mainly by the epithelial cells and to a minor extent by the stromal cells of human prostate glands. In situ RT-PCR is a powerful and straightforward approach for the routine and rapid detection of cellular specific expression of low copy genes.

Incidence of neuroendocrine cells in the seminal vesicles and the prostate--an immunohistochemical study

INTRODUCTION

Prostate and seminal vesicles (sv) are both androgen-dependent male sex accessory glands. The cancer incidence in these two organs is vastly different. Neuroendocrine (NE) cells are involved in the regulation of prostate growth, differentiation and in prostate cancer carcinogenesis. Thus, knowledge of the incidence of NE cells in sv may add to our understanding of prostate cancer etiology.

METHODS

Samples of histologically confirmed normal prostate tissue and normal sv tissue from 20 men were immunostained for chromogranin A. The incidence of stained cells was evaluated semiquantitately.

RESULTS

Neuroendocrine cells were detected in all prostate specimens, but not a single stained cell was found in any of the sv specimens.

CONCLUSIONS

The lack of NE cells and, subsequently, of biogenic amines, peptides and growth factors may be a reason for the low cancer incidence in the seminal vesicles. Alternatively, the absence of NE cells can be seen as a hint that the stem cells of the prostate and sv react differently to endogenous and exogenous stimuli, and thus in the seminal vesicles, stem cells are not transformed into NE cells.

Ultrastructural and immunocytochemical analyses of opioid treatment effects on PC3 prostatic cancer cells

Some opioid peptides are able to inhibit the growth of human prostatic cancer cells; in particular, the [D-Ala(2),D-Leu(5)] enkephalin (DADLE) reduces PC3 cell growth. In order to understand how DADLE decreases cell proliferation, we investigated, by electron microscopy, its effects on PC3 cellular components. PC3 cells were incubated with DADLE and processed for both ultrastructural morphology and immunoelectron microscopy. Some cells were incubated with BrU to determine the transcriptional rate. BrU and DADLE molecules were detected by immunogold techniques and the labeling was quantitatively evaluated. Modifications of some cytoplasmic and nuclear components were observed in DADLE-treated cells. Moreover, treated cells incorporated lower amounts of BrU than control cells. DADLE molecules were located in the cytoplasm and in the nucleus, especially on mRNA transcription and early splicing sites. Our data suggest that DADLE is able to slow down the synthetic activity of PC3 cells, perhaps interfering with nuclear functions.

The diffuse endocrine system: from embryogenesis to carcinogenesis

In the present review we will summarise the current knowledge about the cells comprising the Diffuse Endocrine System (DES) in mammalian organs. We will describe the morphological, histochemical and functional traits of these cells in three major systems gastrointestinal, respiratory and prostatic. We will also focus on some aspects of their ontogeny and differentiation, as well as to their relevance in carcinogenesis, especially in neuroendocrine tumors. The first chapter describes the characteristics of DES cells and some of their specific biological and biochemical traits. The second chapter deals with DES in the gastrointestinal organs, with special reference to the new data on the differentiation mechanisms that leads to the appearance of endocrine cells from an undifferentiated stem cell. The third chapter is devoted to DES of the respiratory system and some aspects of its biological role, both, during development and adulthood. Neuroendocrine hyperplasia and neuroendocrine lung tumors are also addressed. Finally, the last chapter deals with the prostatic DES, discussing its probable functional role and its relevance in hormone-resistant prostatic carcinomas.

Receptor protein tyrosine phosphatase alpha signaling is involved in androgen depletion-induced neuroendocrine differentiation of androgen-sensitive LNCaP human prostate cancer cells

The neuroendocrine (NE) cells represent the third cell population in the normal prostate. Results of several clinical studies strongly indicate that the NE cell population is greatly increased in prostate carcinomas during androgen ablation therapy that correlates with hormone-refractory growth and poor prognosis. However, the mechanism of NE cell enrichment in prostate carcinoma remains an enigma. We investigated the molecular mechanism by which androgen-sensitive C-33 LNCaP human prostate cancer cells become NE-like cells in an androgen-reduced environment, mimicking clinical phenomenon. In the androgen-depleted condition, androgen-sensitive C-33 LNCaP cells gradually acquired the NE-like morphology and expressed an increased level of neuron-specific enolase (NSE), a classical marker of neuronal cells. Several NE-like subclone cells were established. Biochemical characterizations of these subclone cells showed that receptor-type protein-tyrosine phosphatase alpha (RPTPalpha) is elevated and ERK is constitutively activated, several folds higher than that in parental cells. In androgen-depleted condition, PD98059, an MEK inhibitor, could efficiently block not only the activation of ERK, but also the acquisition of the NE-like morphology and the elevation of NSE in C-33 LNCaP cells. In RPTPalpha cDNA-transfected C-33 LNCaP cells, ERK was activated and NSE was elevated. In those cells in the presence of PD98059, the ERK activation and NSE elevation were abolished, following a dose-response fashion. Additionally, in constitutively active MEK mutant cDNA-transfected C-33 LNCaP cells, ERK was activated and NSE level was elevated, and cells obtained the NE-like phenotype. Our data collectively indicated that RPTPalpha signaling via ERK is involved in the NE transdifferentiation of androgen-sensitive C-33 LNCaP human prostate cancer cells in the androgen-depleted condition.

Characterization of the novel amplified in breast cancer-1 (NABC1) gene product

Positional cloning of the cancer-associated 20q13.2 amplicon identified two genes that display high mRNA levels in breast tumors and here we report the initial characterization of one of these gene products, designated Novel Amplified in Breast Cancer-1 (NABC1). Analysis of the primary structure of the NABC1 protein uncovered two regions of this protein with a high likelihood of forming coiled-coils and assembly of a mouse NABC1 cDNA showed that this protein is conserved between mouse and man. NABC1 antisera showed that, like its transcript, breast tumor lines that harbor amplification of 20q13.2 display high levels of the NABC1 protein compared to normal human fibroblasts or a breast cancer line that does not overexpress the NABC1 mRNA. Further, we conclude from studies using in vivo and in vitro approaches that the NABC1 protein forms detergent stable homodimers, and it is this homodimeric form that accumulates in cells that overexpress this protein. NABC1 mRNA exhibits a limited expression pattern in human tissue with high relative transcript levels observed only in brain and prostate. Immunofluorescence microscopy indicates NABC1 displays a punctate localization pattern in the cytoplasm of cultured cells, but biochemical fractionation indicates that this protein is not an integral component of membranous cytoplasmic organelles. Finally, overexpression of human NABC1 in mouse NIH/3T3 cells did not affect either the growth rate or anchorage-dependent growth properties, suggesting that NABC1 is not a prototypical oncogene.

Relief by botulinum toxin of voiding dysfunction due to benign prostatic hyperplasia: results of a randomized, placebo-controlled study

OBJECTIVES

To evaluate the therapeutic role of botulinum toxin injection in men with benign prostatic hyperplasia.

METHODS

Men with benign prostatic hyperplasia were enrolled in a randomized, placebo-controlled study. After a baseline evaluation, each participant received 4 mL of solution injected into the prostate gland. Patients in the control group received saline solution and patients in the treated group received 200 U of botulinum toxin A. The outcome of each group was evaluated by comparing the symptom scores, serum prostate-specific antigen concentration, prostate volume, postvoid residual urine volume, and peak urinary flow rates.

RESULTS

Thirty consecutive patients were enrolled. No local complications or systemic side effects were observed in any patient. After 2 months, 13 patients in the treated group and 3 in the control group had subjective symptomatic relief (P = 0.0007). In patients who received botulinum toxin, the symptom score was reduced by 65% compared with baseline values and the serum prostate-specific antigen concentration by 51% from baseline. In patients who received saline, the symptom score and serum prostate-specific antigen concentration were not significantly changed compared with the baseline values and 1-month values. Follow-up averaged 19.6 +/- 3.8 months.

CONCLUSIONS

Botulinum toxin injected into the prostate seems to be a promising approach for the treatment of benign prostatic hyperplasia. It is safe, effective, and well-tolerated. Furthermore, it is not related to the patient's willingness to complete treatment.

Immunohistochemical detection of gastrin releasing peptide in patients with prostate cancer

Gastrin releasing peptide (GRP) is a neuropeptide that has been suggested to play a role in the development of some malignancies. Our aim was: (1) to identify the expression of GRP in cancerous prostate glands, and (2) to correlate its expression to various pathological parameters and to the patient's clinical outcome. Using standard immunohistochemistry, we evaluated GRP expression in both biopsy and radical prostatectomy specimens from 30 patients with prostatic adenocarcinomas. GRP was expressed in 18 radical prostatectomy specimens (60%) and in 15 biopsies (50%). There was an association between positive immunoexpression of GRP, relapse ( P=0.029) and advanced tumor stages (i.e. pT3, pT4) ( P=0.049). In the respective biopsies, GRP immunostatus was similar to that observed in the subsequent radical prostatectomy specimens. GRP immunoexpression may be of some value as a diagnostic and prognostic marker. Patients whose pathology specimens demonstrate GRP immunopositivity should be closely monitored, since they appear to be at higher risk of disease progression and relapse.

VIP and PACAP are autocrine factors that protect the androgen-independent prostate cancer cell line PC-3 from apoptosis induced by serum withdrawal

1. In the present study, we describe the expression of the neuropeptides vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) as well as their receptors in PC-3 cells, a human prostate cancer cell line. In addition, we have investigated their role in apoptosis induced by serum starvation. 2. By RT-PCR and immunocytochemistry assays, we have demonstrated the production of VIP and PACAP in PC-3 cells. 3. We have demonstrated by RT-PCR and binding assays the expression of common PACAP/VIP (VPAC(1) and VPAC(2)) receptors, but not PACAP-specific (PAC(1)) receptors. The pharmacological profile of [(125)I]-VIP binding assays was as follows: VPAC(1) antagonist=VPAC(1) agonist>VIP>VPAC(2) agonist (IC(50)=1.2, 1.5, 2.3 and 30 nM, respectively). In addition, both receptor subtypes are functional since VIP, PACAP-27 or VPAC(1) and VPAC(2) agonists all increased the intracellular levels of cAMP. 4. The expression of both peptides and their receptors is similar in serum-cultured and serum-deprived PC-3 cells. The treatment of serum-deprived PC-3 cells with exogenous VIP or PACAP-27 increases cell number and viability in a dose-dependent manner, as demonstrated by cellular counting and MTT assays. The increased cell survival is exerted through the VPAC(1) receptor, since a VPAC(1), but not VPAC(2), receptor agonist, mimics the effects and a VPAC(1) receptor antagonist blocks it. Moreover, VIP and PACAP-27 inhibit genomic DNA fragmentation in PC-3 cells triggered by serum starvation, and increase the immunoreactivity of the antiapoptotic protein bcl-2. 5. Our results suggest that VIP and PACAP are autocrine/paracrine factors that protect PC-3 cells from apoptosis through VPAC1 receptors.

Hormone-refractory prostate cancer: a multi-step and multi-event process

Since the pioneering studies of Huggins in 1941, it has been known that prostate cancer cells, like certain normal epithelial cells, can chronically depend on a critical level of androgenic stimulation for their continuous growth and survival. The entire issue of the development of resistance to androgen ablation therapy for metastatic prostate cancer is based on the fact that a portion of cells can survive without androgen stimulation. The cell mechanism of androgen independent status is unclear. For some authors, a portion of the cells present within a patient with a prostate cancer before therapy is naturally androgen independent (selection hypothesis). However, this hypothesis does not consider gene alteration during prostate cancer natural history and probably hormone-refractory prostate cancer (HRPC) is due to a multi-step and multi-event process. In this literature review, different cell pathways that lead to HRPC are described.Prostate Cancer and Prostatic Diseases (2001) 4, 204-212.

Stereologic estimation of the number of neuroendocrine cells in normal human prostate detected by immunohistochemistry

Neuroendocrine cells may play a role in both normal and pathologic conditions of the human prostate. It may be interesting to investigate 1) whether there are significant amounts of neuroendocrine cells in human adult normal prostate, and 2) whether the distribution of these cells shows regional differences. This study estimates both absolute and relative amounts of neuroendocrine cells immunostained for two neuronal markers (chromogranin A and protein gene product 9.5) and for serotonin in the three regions of human prostate, transition zone, central zone, and peripheral zone, using unbiased stereologic measurements. There was observed a predominance of neuroendocrine cells in the transition zone of the normal prostate. The neuroendocrine cells of this region may play a role in the genesis of benign prostate hyperplasia. The significant presence of neuroendocrine cells secreting neuropeptides in peripheral zone could be correlated with the induction of androgen-independent growth in prostate carcinogenesis. The wolffian origin attributed to the central zone can explain its poor population of neuroendocrine cells.

Serum pro-gastrin-releasing peptide (31-98) in benign prostatic hyperplasia and prostatic carcinoma

OBJECTIVES

To clarify whether serum levels of pro-gastrin-releasing peptide (ProGRP) (31-98) could be a useful marker in patients with prostatic carcinoma. GRP is produced and secreted by prostatic neuroendocrine cells.

METHODS

Serum levels of ProGRP(31-98) were measured by enzyme-linked immunosorbent assay in 20 patients with benign prostatic hyperplasia and 107 patients with prostatic carcinoma.

RESULTS

The mean serum levels of ProGRP(31-98) in patients with distant metastasis and hormone-resistant prostate cancer were significantly elevated compared with those in patients with organ-confined disease. Significantly elevated levels of ProGRP(31-98) were detected in 9 patients with prostatic carcinoma before any treatment. During hormone-resistant prostate cancer progression, ProGRP(31-98) levels were elevated in 9 patients (23%). Of the 9 patients with Stage D3 and elevated serum ProGRP, 4 had a normal serum prostate-specific antigen level.

CONCLUSIONS

ProGRP may be a potential tumor marker for prostate cancer. Additional studies in large groups of patients are needed to define the clinical value of ProGRP.

Neuroendocrine differentiation of the LNCaP prostate cancer cell line maintains the expression and function of VIP and PACAP receptors

The molecular mechanisms involved in differentiation of prostate cancer cells to a neuroendocrine (NE) cell phenotype are not well understood. Here we used the androgen-dependent human prostate cancer cell line LNCaP to perform a systematic and broad analysis of the expression, pharmacology, and functionality of vasoactive intestinal peptide (VIP)/pituitary adenylate cyclase-activating peptide (PACAP) receptors. Reverse transcription polymerase chain reaction experiments, together with pharmacological approaches with a set of specific agonists and antagonists, demonstrated the presence of the three VIP/PACAP receptor subtypes (PAC1, VPAC1, and VPAC2 with a major role for VPAC1, acting through adenylate cyclase (AC) stimulation. An essentially similar pattern was observed by NE differentiated cells (4 days after serum deprivation) in spite of the important morphological changes observed. However, the expression of the prostate-specific antigen (PSA) decreased in NE cells (and increased again by dihydrotestosterone, DHT, treatment). The present demonstration of the induction of NE transdifferentiation in LNCaP cells by increasing concentrations of VIP adds value to previous observations on the role of cAMP in this process, an interesting topic in the comprehension of the molecular changes that are involved in the progression of prostate cancer to androgen independence.

Serum chromogranin-A in advanced prostate cancer

OBJECTIVE

To determine the value of serum chromogranin A (CgA), a marker of neuroendocrine differentiation, for monitoring prostate cancer: CgA levels were related to three other tumour markers, i.e. total prostate-specific antigen (tPSA), prostatic acid phosphatase (PAP), neurone-specific enolase (NSE), and to testosterone, to assess the importance of hormone withdrawal.

PATIENTS AND METHODS

Serum samples (218) were obtained from 118 patients with prostate cancer, including 111 patients with advanced prostate cancer: 103 presented to our centre for systemic radionuclide therapy of painful skeletal metastases. CgA concentrations were measured using a new immunoradiometric assay (IRMA: Cis Bio International, Gif sur Yvette, France) and a threshold of 70 ng/mL was determined after receiver operating characteristic curve analysis. Testosterone was also measured with an IRMA assay; tPSA, PAP and NSE were assayed using the time-resolved amplified cryptate emission.

RESULTS

Serum marker levels were high in 64% of the patients for CgA, 24% for NSE, 89% for tPSA and 81% for PAP. Patients resistant to endocrine treatments and with elevated tPSA (i.e. hormone-independent) showed increased CgA and NSE in 62% and 29%, respectively. Patients with hormone-dependent prostate cancer (i.e. with a normal tPSA level) had elevated CgA in 59% but no abnormal NSE. All patients of the latter group except one showed clinical progression of their disease. However, the mean (SD) concentrations of CgA in hormone-independent (146) or hormone-dependent (22) patients, at 185.3 (449.1) and 160.9 (293.9) ng/mL, respectively, were not statistically different (P=0.8, Mann-Whitney U-test). For 30 patients, blood samples were drawn and markers measured before and after systemic radionuclide therapy. There was a significant increase in the CgA and tPSA concentrations after treatment (P=0.0146 and 0.0025, respectively).

CONCLUSIONS

In association with tPSA, serum CgA appears to be a promising marker for monitoring patients with prostate cancer.

Regulation of prostate-specific antigen (PSA) gene expression and release in LNCaP prostate cancer by antagonists of growth hormone-releasing hormone and vasoactive intestinal peptide

BACKGROUND

Prostate-specific antigen (PSA) is the best tumor marker for diagnosis and prognosis of prostatic carcinoma. The secretion of PSA from LNCaP human prostate cancer cells is influenced by acute stimuli such as vasoactive intestinal peptide (VIP), growth hormone-releasing hormone (GHRH), and chronic stimuli like androgens.

METHODS

To study the regulation of basal and VIP/GHRH or androgen-stimulated secretion from LNCaP cells, we used a superfusion system, which allowed us to simultaneously measure PSA gene expression, PSA secretion, and cAMP release from the same cancer cells. LNCaP cancer cells were also implanted orthotopically into nude mice.

RESULTS

VIP (30 pM-3 nM), GHRH (3 nM-300 nM), and dihydrotestosterone (100 nM) induced a significant increase in PSA gene expression, PSA secretion, and cAMP release. The dose and time-dependent effects of peptides were manifested only in the presence of androgens. At the end of continuous stimulation of cells with 1 nM VIP for 2 hr, large amounts of stored immunoreactive PSA still remained in the cells. Adenylate cyclase activator, forskolin (FSK), significantly increased PSA secretion and gene expression, and potassium, which causes nonspecific depolarization of membranes, augmented gene expression, and secretion of PSA, but did not influence cAMP release. This suggests that PSA secretion is regulated by cAMP-dependent as well as cAMP-independent pathways. In superfusion system, stimulatory effects of VIP and GHRH on PSA secretion were inhibited by VIP antagonist JV-1-53, and less by GHRH antagonist JV-1-38. In cell cultures, JV-1-38 had a stronger inhibitory effect on proliferation, indicating an involvement of the recently discovered tumoral GHRH receptors in this process. In nude mice, with orthotopically implanted LNCaP cancer cells, GHRH antagonist JV-1-38 alone or androgen ablation by castration had no effect on tumor growth and PSA levels. However, castration combined with treatment with GHRH antagonist, significantly decreased tumor growth and PSA secretion.

CONCLUSIONS

Our findings suggest that the secretion of PSA is regulated rather than constitutive, contrary to previous reports. In addition, the effect of GHRH and VIP antagonists on PSA secretion from prostate cancer cells is not correlated with their antiproliferative action.