Proliferation and differentiation of prostatic stromal cells

Circadian rhythm in prostate cancer: time to take notice of the clock

The circadian clock is an evolutionary molecular product that is associated with better adaptation to changes in the external environment. Disruption of the circadian rhythm plays a critical role in tumorigenesis of many kinds of cancers, including prostate cancer (PCa). Integrating circadian rhythm into PCa research not only brings a closer understanding of the mechanisms of PCa but also provides new and effective options for the precise treatment of patients with PCa. This review begins with patterns of the circadian clock, highlights the role of the disruption of circadian rhythms in PCa at the epidemiological and molecular levels, and discusses possible new approaches to PCa therapy that target the circadian clock.

Endocrine, prostatic vascular, and proapoptotic changes in dogs with benign prostatic hyperplasia treated medically or surgically

Benign prostatic hyperplasia (BPH) is a disorder related to hormone imbalance, local angiogenesis, and prostate growth, which can be treated surgically (orchiectomy) or medically (most commonly with finasteride). However, finasteride therapy is not completely established in dogs regarding local action and posology. This study aimed to evaluate the effect of different doses of finasteride and orchiectomy on hormonal profile, prostate apoptosis, blood flow, and biometry in dogs with BPH. Dogs were assigned to the following groups: untreated, 0.1 mg, 0.2 mg, and 0.5 mg/kg/d of finasteride and orchiectomy. All dogs were assessed monthly: day 0 (before treatment), day 30, and day 60 and subjected to prostate B-mode and Doppler ultrasonography and hormonal analysis (testosterone and dihydrotestosterone). After 60 d, prostatic biopsy was performed for histology and immunohistochemical evaluation for apoptosis (caspase-3). On day 60, percentage reduction of prostatic volume was greater in orchiectomized dogs than that in finasteride groups, which, conversely, was greater than untreated dogs. On day 60, 0.2-mg finasteride, 0.5-mg finasteride, and orchiectomy groups had higher prostatic blood flow than 0.1-mg finasteride and untreated groups. In addition, both 0.5-mg finasteride and orchiectomy groups had an increase in prostate artery resistance. Orchiectomy significantly decreased androgen concentrations at 30 d onward, differing from the remaining groups. The orchiectomy group had lower caspase-3 immunostaining, however, not different from untreated and 0.5-mg finasteride. In conclusion, 0.5 mg/kg finasteride promoted more effective prostate apoptosis and hemodynamic effects among medical treatments, whereas orchiectomy caused prostate atrophy and sharp endocrine changes in dogs with BPH.

Mangosteen pericarp components alleviate progression of prostatic hyperplasia and mitochondrial dysfunction in rats

Prostatic hyperplasia, characterized by progressive hyperplasia of glandular and stromal tissues, is the most common proliferative abnormality of the prostate in aging men. A high-fat diet (HFD) usually is a major factor inducing oxidative stress, inflammation, and an abnormal state of the prostate. Mangosteen pericarp powder (MPP) has abundant xanthones which can be antioxidant, anti-inflammatory, and antiproliferative agents. Therefore, the purpose of this study was to research whether MPP supplementation can affect the progression of prostatic hyperplasia. Twenty-four male F344 rats were randomly divided into four groups, including a control group (C), prostatic hyperplasia-induced group (P), prostatic hyperplasia-induced with low-dose MPP group (PL), and induced with high-dose MPP group (PH). The P, PL, and PH groups were given weekly intraperitoneal injections of 3,2′-dimethyl-4-aminobiphenyl (DMAB) at 25 mg/kg body weight for 10 weeks, and simultaneously fed an HFD for 24 weeks. Our findings first demonstrated that MPP consumption significantly decreased the prostate weight, serum testosterone and dihydrotestosterone concentrations, protein expression of proliferating cell nuclear antigen, and malondialdehyde levels and ameliorated mitochondrial function in prostatic tissues. These results suggest that MPP supplementation could be used to attenuate the progression of prostatic hyperplasia.

Genomic analysis of benign prostatic hyperplasia implicates cellular re-landscaping in disease pathogenesis

Benign prostatic hyperplasia (BPH) is the most common cause of lower urinary tract symptoms in men. Current treatments target prostate physiology rather than BPH pathophysiology and are only partially effective. Here, we applied next-generation sequencing to gain new insight into BPH. By RNAseq, we uncovered transcriptional heterogeneity among BPH cases, where a 65-gene BPH stromal signature correlated with symptom severity. Stromal signaling molecules BMP5 and CXCL13 were enriched in BPH while estrogen regulated pathways were depleted. Notably, BMP5 addition to cultured prostatic myofibroblasts altered their expression profile towards a BPH profile that included the BPH stromal signature. RNAseq also suggested an altered cellular milieu in BPH, which we verified by immunohistochemistry and single-cell RNAseq. In particular, BPH tissues exhibited enrichment of myofibroblast subsets, whilst depletion of neuroendocrine cells and an estrogen receptor (ESR1)-positive fibroblast cell type residing near epithelium. By whole-exome sequencing, we uncovered somatic single-nucleotide variants (SNVs) in BPH, of uncertain pathogenic significance but indicative of clonal cell expansions. Thus, genomic characterization of BPH has identified a clinically-relevant stromal signature and new candidate disease pathways (including a likely role for BMP5 signaling), and reveals BPH to be not merely a hyperplasia, but rather a fundamental re-landscaping of cell types.

Elevation of Stromal-Derived Mediators of Inflammation Promote Prostate Cancer Progression in African-American Men

Progress in prostate cancer racial disparity research has been hampered by a lack of appropriate research tools and better understanding of the tumor biology. Recent gene expression studies suggest that the tumor microenvironment (TME) may contribute to racially disparate clinical outcomes in prostate cancer. Analysis of the prostate TME has shown increased reactive stroma associated with chronic inflammatory infiltrates in African-American (AA) compared with European-American (EA) patients with prostate cancer. To better understand stromal drivers of changes in TME, we isolated prostate fibroblasts (PrF) from AA (PrF^-AA) and EA (PrF^-EA) prostate cancer tissues and studied their functional characteristics. PrF^-AA showed increased growth response to androgens FGF2 and platelet-derived growth factor. Compared with PrF^-EA, conditioned media from PrF^-AA significantly enhanced the proliferation and motility of prostate cancer cell lines. Expression of markers associated with myofibroblast activation (αSMA, vimentin, and tenascin-C) was elevated in PrF^-AA In vivo tumorigenicity of an AA patient-derived prostatic epithelial cell line E006AA was significantly increased in the presence of PrF^-AA compared with PrF^-EA, and RNA-seq data and cytokine array analysis identified a panel of potential proinflammatory paracrine mediators (BDNF, CHI3L1, DPPIV, FGF7, IL18BP, IL6, and VEGF) to be enriched in PrF^-AA E006AA cell lines showed increased responsiveness to BDNF ligand compared with EA-derived LNCaP and C4-2B cells. Addition of a TrkB-specific antagonist significantly reduced the protumorigenic effects induced by PrF^-AA compared with PrF^-EA These findings suggest that fibroblasts in the TME of AA patients may contribute to the health disparity observed in the incidence and progression of prostate cancer tumors.Significance: These findings suggest that stromal cells in the tumor microenvironment of African-American men promote progression of prostate cancer by increasing levels of a specific set of pro-inflammatory molecules compared with European-American men.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/21/6134/F1.large.jpg Cancer Res; 78(21); 6134-45. ©2018 AACR.

Testosterone Rescues the De-Differentiation of Smooth Muscle Cells Through Serum Response Factor/Myocardin

Prostatic smooth muscle cells (pSMCs) differentiation is a key factor for prostatic homeostasis, with androgens exerting multiple effects on these cells. Here, we demonstrated that the myodifferentiator complex Srf/Myocd is up-regulated by testosterone in a dose-dependent manner in primary cultures of rat pSMCs, which was associated to the increase in Acta2, Cnn1, and Lmod1 expressions. Blocking Srf or Myocd by siRNAs inhibited the myodifferentiator effect of testosterone. While LPS led to a dedifferentiated phenotype in pSMCs, characterized by down-regulation of Srf/Myocd and smooth muscle cell (SMC)-restricted genes, endotoxin treatment on Myocd-overexpressing cells did not result in phenotypic alterations. Testosterone at a physiological dose was able to restore the muscular phenotype by normalizing Srf/Myocd expression in inflammation-induced dedifferentiated pSMCs. Moreover, the androgen reestablished the proliferation rate and IL-6 secretion increased by LPS. These results provide novel evidence regarding the myodifferentiating role of testosterone on SMCs by modulating Srf/Myocd. Thus, androgens preserve prostatic SMC phenotype, which is essential to maintain the normal structure and function of the prostate. J. Cell. Physiol. 232: 2806-2817, 2017. © 2016 Wiley Periodicals, Inc.

The impact of finasteride and dutasteride treatments on proliferation, apoptosis, androgen receptor, 5α-reductase 1 and 5α-reductase 2 in TRAMP mouse prostates

BACKGROUND

Previously, we studied the effect of finasteride- or dutasteride-containing diets in male C57BL/6 TRAMP x FVB mice. Pre (6 weeks of age) and post (12 weeks of age) groups received finasteride or dutasteride to determine the efficacy of these pharmaceuticals on prostate cancer (PCa) development in male C57BL/6 TRAMP x FVB mice. Post-Dutasteride treatment was more effective than Pre-Dutasteride treatment, and dutasteride treatments were more effective than finasteride treatments in decreasing prostatic intraepithelial neoplasia (PIN) progression and PCa development. Finasteride and Pre-Dutasteride treatments significantly decreased high-grade PIN incidence, but increased poorly differentiated PCa incidence. In this study, molecular changes in prostates of these mice were characterized in an effort to elucidate the discordant response in Pre-Dutasteride and finasteride groups, and determine why Post-Dutasteride treatment was more effective.

METHOD/PRINCIPAL FINDINGS

Ki-67 (proliferation marker) and androgen receptor (AR) protein, apoptotic DNA fragmentation (TUNEL assay), 5α-reductase 1 (5αR1) and 5α-reductase 2 (5αR2) mRNA were quantified in male TRAMP mice prostate tissues with genitourinary weight < 1 and > 1 gram. Overall, proliferation and AR were decreased and apoptosis was increased in most tumors versus prostate epithelium and hyperplasia. Proliferation and AR were increased notably in hyperplasia versus prostate epithelium and tumor. There were no clear trends or differences in 5α-reductase 1 and 5α-reductase 2 levels between large and small tumors. The discordant response in Pre-Finasteride and Pre-Dutasteride groups may be due to upregulated 5αR1 levels in large versus small tumors. It is not clear what the mechanism is for the different response in the Post-Finasteride group. Post-Dutasteride treatment was more effective than Pre-Dutasteride treatment in decreasing 5αR1 in large tumors. Therefore, this may be why this treatment was more effective in decreasing PIN progression and PCa development.

CONCLUSION

The effect of finasteride and dutasteride on these biomarkers did not clearly elucidate their mechanism of action, but tumor 5αR1 levels were significantly positively correlated with adjusted prostate severe lesion score.

Benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH), which causes lower urinary tract symptoms (LUTS), is a common diagnosis among the ageing male population with increasing prevalence. Many risks factors, both modifiable and non-modifiable, can increase the risk of development and progression of BPH and LUTS. The symptoms can be obstructive (resulting in urinary hesitancy, weak stream, straining or prolonged voiding) or irritative (resulting in increased urinary frequency and urgency, nocturia, urge incontinence and reduced voiding volumes), or can affect the patient after micturition (for example, postvoid dribble or incomplete emptying). BPH occurs when both stromal and epithelial cells of the prostate in the transitional zone proliferate by processes that are thought to be influenced by inflammation and sex hormones, causing prostate enlargement. Patients with LUTS undergo several key diagnostic investigations before being diagnosed with BPH. Treatment options for men with BPH start at watchful waiting and progress through medical to surgical interventions. For the majority of patients, the starting point on the treatment pathway will be dictated by their symptoms and degree of bother.

Prostatic Artery Embolization (PAE) for Symptomatic Benign Prostatic Hyperplasia (BPH): Part 1, Pathological Background and Clinical Implications

Pathological features of benign prostatic hyperplasia (BPH) dictate various responses to prostatic artery embolization (PAE). Typically, BPH originates in the transition zone and periurethral region, where should be considered the primary target area in PAE procedures. Given that histological heterogeneity of components in hyperplasia nodules, epithelial or stromal, identifying the more responsive nodules to PAE will have clinical implications. Since some lower urinary tract symptoms (LUTS) in patients with BPH are usually related to bladder outlet obstruction-induced changes in bladder function rather than to outflow obstruction directly, proper selection of candidate patients prior to PAE is of great clinical importance. BPH is a typical chronic progressive condition, suggesting PAE could aim not only to relieve LUTS but also to delay or prevent the clinical progression. Awareness of the pathological background of BPH is essential for interventional radiologists to improve clinical outcomes and develop new treatment strategies in clinical practice of PAE.

Chromosome damage, apoptosis, and necrosis in exfoliated cells of oral mucosa from androgenic anabolic steroids users

The aim of this study was to evaluate the potential of the androgenic anabolic steroids (AAS) for inducing chromosome damage, apoptosis, and necrosis, using the micronucleus test on exfoliated cells from the oral mucosa of AAS users. The sample consisted of 55 male individuals, practitioners of physical exercise divided into two groups: 25 individuals who were users of AAS and 30 individuals in the control group. Cytological analysis included, in addition to micronuclei, counting of broken eggs and degenerative nuclear changes indicative of apoptosis (karyorrhexis, condensed chromatin, and pyknosis) and necrosis (karyolysis in addition to these changes). The statistical analysis did not show differences in occurrences of micronuclei, karyolysis, and broken eggs between the groups. The occurrence of apoptosis was significantly higher in cells from control subjects. The results obtained showed that inhibition of apoptosis was induced by AAS, suggesting that this may be one of the mechanisms contributing toward the association that has been described between use of AAS and the carcinogenic process.

Cooperative effects of EGF, FGF, and TGF-β1 in prostate stromal cells are different from responses to single growth factors

AIMS

Stromal growth is critical for prostate enlargement during benign prostatic hyperplasia (BPH). While responses of prostate cells to single growth factors have been well characterized, responses to multiple growth factors at once are poorly understood. Here, we examined the effects of combinations between epidermal growth factor (EGF), fibroblast growth factor (FGF), and transforming growth factor-β1 (TGF-β1) in human prostate stromal cells.

MAIN METHODS

EGF, FGF, and TGF-β1 were applied to WPMY-1 cells, an immortalized, non-malignant line of stromal cells from the human prostate. Hypertrophic responses were assessed by protein/DNA ratio, and cyclin D1 mRNA by RT-PCR. Expression of EGF, FGF, and TGF-β1 and their receptors in human prostate tissue was analyzed by RT-PCR, Western blot, and fluorescence staining.

KEY FINDINGS

Hypertrophic responses to single growth factors and combinations were similar. Combinations showed additive effects on cyclin D1 mRNA. Combination of EGF with TGF-β1, but not EGF or TGF-β1 alone, caused assembly of cells to a new two-dimensional structure, being characterized by dense aggregates connected by branches of few cells. EGF and TGF-β1 were detected together in human prostates. Receptors for EGF and TGF-β colocalized on stromal cells in human prostates.

SIGNIFICANCE

Responses of prostate stromal cells to combinations of EGF, FGF, and TGF-β1 may be quantitatively different, qualitatively different, or similar to responses to single growth factors. The combination of EGF and TGF-β1, but not EGF or TGF-β1 alone, induces aggregation of prostate stromal cells, which may be relevant for morphogenesis.

Stromal nodules in benign prostatic hyperplasia: morphologic and immunohistochemical characteristics

BACKGROUND

One hundred forty nine stromal nodules (SNs) from transurethral resection of benign prostatic hyperplasia specimens in 39 patients (57-85 years with mean of 70.9) were investigated to characterize the SNs and to outline the etiopathogenesis of solitary fibrous tumors (SFTs) and gastrointestinal stromal tumors (GISTs) of prostate by immunohistochemistry performed on tissue microarray sections.

METHODS

Antibodies used included smooth muscle actin, desmin, vimentin, and S-100 protein for subtyping, vascular endothelial growth factor, insulin-like growth factor-1, fibroblast growth factor, and TGF-ß as growth factors; CD133, c-KIT, CD34, and CD44 as stem cell markers; and estrogen (ER), progesterone (PR), and androgen receptor (AR) as hormone receptors.

RESULTS

SNs were classified into four subtypes: (1) immature mesenchymal (n = 7, 4.7%); (2) fibroblastic (n = 74, 49.7%); (3) fibromuscular (n = 53, 35.6%); and (4) smooth muscular (n = 15, 10.1%) types. There were linear trends of the expression of all growth factors (VEGF, IGF-1, FGF, TGF-ß), but only CD44 stem cell marker and AR hormone receptor as maturation progressed from immature mesenchymal to smooth muscular type (Ptrend  < 0.05). S-100, c-KIT, and ER were not expressed in any types of SNs. CD34 was positive in 55% of the SNs (82/149).

CONCLUSIONS

The data suggest that AR and growth factors are important factors for maturation of SNs, but not influenced by the administration of 5-alpha reductase inhibitor (5ARI). Although the cells comprising the SNs seem to be not associated with the origin of prostatic GISTs, there is a possibility of a tentative link of SFTs arising from SNs of the prostate.

Hic-5 influences genomic and non-genomic actions of the androgen receptor in prostate myofibroblasts

There is extensive knowledge of androgen receptor (AR) signaling in cancer cells, but less regarding androgen action in stromal cells of the tumor microenvironment. We report here the genome-wide effects of a stromal cell specific molecular adapter and AR coregulator, hydrogen peroxide-inducible gene 5 (Hic-5/TGFB1I1), on AR function in prostate myofibroblasts. Following androgen stimulation, Hic-5 rapidly translocates to the nucleus, coincident with increased phosphorylation of focal adhesion kinase. As a coregulator, Hic-5 acted to amplify or inhibit regulation of approximately 50% of AR target genes, affected androgen regulation of growth, cell adhesion, motility and invasion. These data suggest Hic-5 as a transferable adaptor between focal adhesions and the nucleus of prostate myofibroblasts, where it acts a key mediator of the specificity and sensitivity of AR signaling. We propose a model in which Hic-5 coordinates AR signaling with adhesion and extracellular matrix contacts to regulate cell behavior in the tumor microenvironment.

Prostatic ischemia induces ventral prostatic hyperplasia in the SHR; possible mechanism of development of BPH

In the light of increasing evidence that benign prostatic hyperplasia is associated with cardiovascular disease, we have investigated the relationship between prostatic blood flow and prostatic hyperplasia in the spontaneously-hypertensive-rat (SHR). Twelve-week-old male SHRs were treated with nicorandil for six weeks. Wistar-Kyoto rats were used as controls. Six weeks after nicorandil treatment, blood pressure and the prostatic blood flow were estimated, and tissue levels of malondialdehyde, HIF-1α, TGF-β1, bFGF, dihydrotestosterone, and α-SMA were measured. SHRs showed significant increases in blood pressure, tissue levels of malondialdehyde, HIF-1α, TGF-β1, bFGF, α-SMA and a significant decrease in the prostatic blood flow. Although treatment with nicorandil failed to alter the blood-pressure and α-SMA, it significantly ameliorated the increased levels of malondialdehyde, HIF-1α, TGF-β1, and bFGF. There were no significant differences in tissue levels of dihydrotestosterone among any groups. These data indicate that development of prostatic hyperplasia may be associated with prostatic hypoxia, which nicorandil prevents via its effect to increase the blood flow.

Testosterone regulates smooth muscle contractile pathways in the rat prostate: emphasis on PDE5 signaling

Testosterone (T) plays a permissive role in the development of benign prostatic hyperplasia (BPH), and phosphodiesterase 5 inhibitors (PDE5is) have been found to be effective for BPH and lower urinary tract symptoms (LUTS) in clinical trials. This study investigated the effect of T on smooth muscle (SM) contractile and regulatory signaling pathways, including PDE5 expression and functional activity in prostate in male rats (sham-operated, surgically castrated, and castrated with T supplementation). In vitro organ bath studies, real-time RT-PCR, Western blot analysis, and immunohistochemistry were performed. Castration heavily attenuated contractility, including sensitivity to phenylephrine with SM myosin immunostaining revealing a disrupted SM cell arrangement in the stroma. PDE5 was immunolocalized exclusively in the prostate stroma, and orchiectomy signficantly reduced PDE5 immunopositivity, mRNA, and protein expression, along with nNOS and ROKβ mRNA, whereas it increased eNOS plus α(1a) and α(1b) adrenoreceptor expression in castrated animals. The PDE5i zaprinast significantly increased prostate strip relaxation to the nitric oxide donor sodium nitroprusside (SNP) in control but not castrated rats. But SNP alone was more effective on castrated rats, comparable with sham treated with SNP plus zaprinast. T supplementation prevented or restored all above changes, including SNP and zaprinast in vitro responsiveness. In conclusion, our data show that T positively regulates PDE5 expression and functional activities in prostate, and T ablation not only suppresses prostate size but also reduces prostatic SM contractility, with several potential SM contraction/relaxation pathways implicated. Zaprinast findings strongly suggest a major role for PDE5/cGMP in this signaling cascade. PDE5 inhibition may represent a novel mechanism for treatment of BPH.

The calcium sensor STIM1 is regulated by androgens in prostate stromal cells

BACKGROUND

Prostate development and maintenance in the adult results from an interaction of stromal and glandular components. Androgens can drive this process by direct action on the stroma. We investigated whether there was a direct link between androgens and another key regulator of stromal cells, intracellular Ca2+ ([Ca2+ ]i ).

METHODS

Prostate stromal cells were freshly obtained and cultures derived from patients with benign prostatic hyperplasia. Gene expression in dihydrotestosterone treated and untreated cells was compared using Affymetrix gene expression arrays and Ca2+ regulated features were identified by Gene Ontology (GO). Changes in [Ca2+]i were determined in Fluo-4 loaded cells. Androgen regulation was confirmed by chromatin immunoprecipitaion.

RESULTS

Stromal cell cultures were sorted for expression of integrin α1 β1 , which enriched for cells expressing the androgen receptor (AR). We identified key functional categories, within the androgen-induced gene expression signature, focusing on genes involved in calcium signaling. From this analysis, stromal interaction molecule-1 (STIM1) was identified as a significantly differentially expressed gene with four relevant associated GO terms. DNA sequence analysis showed that the promoter region of STIM1 contained putative androgen response element sequences in which AR binding ability of STIM1 was confirmed. Androgens directly regulated STIM1 expression and STIM1 effects on store-operated calcium entry were inhibited by STIM1 knock-down. Reduced STIM1 expression in prostate stromal cells led to a reduction in basal Ca2+ levels, the amount of Ca2+ released by thapsigargin and a reduction in store filling following TG-induced store depletion.

CONCLUSIONS

These results indicate that androgens modulate [Ca2+]i through the direct regulation of the STIM1 gene by AR binding to the STIM1 promoter.

Increased CK5/CK8-positive intermediate cells with stromal smooth muscle cell atrophy in the mice lacking prostate epithelial androgen receptor

Results from tissue recombination experiments documented well that stromal androgen receptor (AR) plays essential roles in prostate development, but epithelial AR has little roles in prostate development. Using cell specific knockout AR strategy, we generated pes-ARKO mouse with knock out of AR only in the prostate epithelial cells and demonstrated that epithelial AR might also play important roles in the development of prostate gland. We found mice lacking the prostate epithelial AR have increased apoptosis in epithelial CK8-positive luminal cells and increased proliferation in epithelial CK5-positive basal cells. The consequences of these two contrasting results could then lead to the expansion of CK5/CK8-positive intermediate cells, accompanied by stromal atrophy and impaired ductal morphogenesis. Molecular mechanism dissection found AR target gene, TGF-β₁, might play important roles in this epithelial AR-to-stromal morphogenesis modulation. Collectively, these results provided novel information relevant to epithelial AR functions in epithelial-stromal interactions during the development of normal prostate, and suggested AR could also function as suppressor in selective cells within prostate.

Update on corpus cavernosum smooth muscle contractile pathways in erectile function: a role for testosterone?

INTRODUCTION

Normal erectile function (EF) involves a coordinated relaxation of the arteries that supply the penis and the corpus cavernosum smooth muscle (CCSM), resulting in expansion of the sinusoids and increased intracavernous pressure. But the CCSM spends the majority of its time in the contracted state which is mediated by norepinephrine released from nerve endings and other vasoconstrictors like endothelins released from the endothelium. These agents cause smooth muscle myosin (SMM) phosphorylation by elevating intracellular calcium. When calcium returns to basal levels, the calcium sensitivity increases and prevents myosin dephosphorylation, which involves the RhoA/Rho-kinase (ROK) mechanism, thus maintaining force. Although mounting evidences demonstrate that androgens have a major influence on EF that is not just centrally mediated, this notion remains quite controversial.

AIM

To summarize the current knowledge on CCSM contractile pathways, the role they play in modulating EF, and the influence of androgens.

METHODS

The article reviews the literature and contains some previously unpublished data on CCSM contraction signaling including the role that androgens are known to play in modulating these pathways.

MAIN OUTCOME MEASURES

Data from peer-reviewed publications and previously unpublished observations.

RESULTS

In addition to downregulation of many pro-erectile molecular mechanisms, decreased testosterone (T) levels upregulate CCSM contractility, including hyperresponsiveness to α-adrenergic agonists, increased SMM phosphorylation, alteration of SMM isoform composition, activation of RhoA/ROK signaling and modulation of sphingosine-1-phosphate regulation of CCSM tone.

CONCLUSIONS

Decreased T levels upregulate CCSM contractile signaling. Meanwhile, it downregulates CCSM relaxation pathways synergizing to produce erectile dysfunction (ED). Although some urologists and researchers are still skeptical of the influence of androgens on penile erection, understanding these molecular control mechanisms as well as the influence that androgens have on these pathways should provide new evidence supporting the roles of androgens in EF and enhance the discovery of novel targets for drug development to treat ED.

Transforming growth factor β-receptor II protein expression in benign prostatic hyperplasia is associated with prostate volume and inflammation

OBJECTIVE

To assess transforming growth factor β-receptor II (TGFBRII) protein expression in benign prostatic hyperplasia (BPH) using immunohistochemistry analysis, and to compare the analysis with phenotypic properties.

METHODS

TGFBRII protein expression was profiled using three clinical outcome tissue microarrays (TMAs), sampled from 231 patients who underwent surgery for BPH. Using these TMAs, five inflammatory cell markers were also assessed, including CD3, CD4, CD8, CD20, and CD163. The surgical procedure was open prostatectomy in 95 patients and transurethral resection of the prostate in 136 patients.

RESULTS

TGFBRII protein expression was found in BPH epithelium cells for both basal and secretory cells, as well as in fibromuscular stromal cells. TGFBRII staining was also strong in most of the lymphocytes infiltrating the prostate. TGFBRII stromal staining was found to be significantly associated with prostate volume (P = 0.04), whereas TGFBRII epithelial staining was found to be significantly associated with 5-α-reductase-inhibitor medical therapy received by patients before surgery (P = 0.004). Both stromal and epithelial TGFBRII staining were found to be associated with CD4 T-lymphocyte infiltrate, independently of prostate volume (P < 0.001 and P = 0.002).

CONCLUSIONS

TGFBRII protein expression in BPH is associated with prostate gland volume and with CD4 T-lymphocyte prostatitis. TGFBRII might be a promising therapeutic target to prevent prostate enlargement or even to decrease prostate volume.

Acute inflammation promotes early cellular stimulation of the epithelial and stromal compartments of the rat prostate

BACKGROUND

It has been proposed that prostatic inflammation plays a pivotal role in the pathophysiology of benign hyperplasia and prostate cancer. However, little information is available about the prostatic reaction to bacterial compounds in vivo. Our aim was therefore to evaluate the early effects of bacterial infection on rat ventral prostate compartments.

METHODS

Using a rat model of acute bacterial prostatitis by Escherichia coli, we analyzed the histological and ultrastructural changes in the prostate at 24, 48, and 72 hr postinfection. Prostatic tissues were immunostained for prostatic binding protein (PBP), ACTA2, ErbB1, and ErbB2 receptors, TUNEL, and markers of cell proliferation. Dot and Western blots for PBP, ACTA2, ErbB1, ErbB2, and TGFbeta1 were also performed.

RESULTS

The prostatic epithelium became hypertrophied, with increases in PBP and ErbB1 expression at 24 hr postinfection. Moreover, inflammation induced the expression of ErbB2, a receptor strongly involved in carcinogenesis. These alterations were more pronounced at 48 hr, but the epithelium also showed apoptosis and finally atrophy at 72 hr postinfection, with a decrease in PBP and ErbB receptors. Interestingly, the epithelial cells exhibited a high level of proliferation in response to the bacteria. The stromal reaction to acute inflammation was initially characterized by smooth muscle hypertrophy. Afterwards, muscle cells acquired a secretory phenotype, with a reduction in ACTA2 at 72 hr postinfection.

CONCLUSIONS

Prostatic inflammation, even at the early stages, promotes atrophic and proliferative changes, and the upregulation of ErbB receptors together with dedifferentiation of smooth muscle cells. These data suggest that repetitive reinfections could lead to uncontrolled growth in the prostate gland.

Correlation between circadian gene variants and serum levels of sex steroids and insulin-like growth factor-I

A variety of biological processes, including steroid hormone secretion, have circadian rhythms, which are influenced by nine known circadian genes. Previously, we reported that certain variants in circadian genes were associated with risk for prostate cancer. To provide some biological insight into these findings, we examined the relationship of five variants of circadian genes, including NPAS2 (rs2305160:G > A), PER1 (rs2585405:G > C), CSNK1E (rs1005473:A > C), PER3 (54-bp repeat length variant), and CRY2 (rs1401417:G > C), with serum levels of sex steroids and insulin-like growth factor (IGF)-I and IGF-binding protein 3 (IGFBP3) in 241 healthy elderly Chinese men (mean age of 71.5). Age-adjusted and waist-to-hip ratio-adjusted ANOVA followed by likelihood ratio tests (LRT) showed that the NPAS2 variant A allele was associated with lower free and bioavailable testosterone (P(LRT) = 0.02 and 0.01, respectively) compared with the GG genotype. In addition, the PER1 variant was associated with higher serum levels of sex hormone-binding globulin levels (Ptrend = 0.03), decreasing 5alpha-androstane-3alpha, 17beta-diol glucuronide levels (Ptrend = 0.02), and decreasing IGFBP3 levels (Ptrend = 0.05). Furthermore, the CSNK1E variant C allele was associated with higher testosterone to dihydrotestosterone ratios (P(LRT) = 0.01) compared with the AA genotype, whereas the longer PER3 repeat was associated with higher serum levels of IGF-I (P(LRT) = 0.03) and IGF-I to IGFBP3 ratios (P(LRT) = 0.04). The CRY2 polymorphism was not associated with any biomarkers analyzed. Our findings, although in need of confirmation, suggest that variations in circadian genes are associated with serum hormone levels, providing biological support for the role of circadian genes in hormone-related cancers.

Androgen receptor and growth factor signaling cross-talk in prostate cancer cells

Androgens promote the growth and differentiation of prostate cells through ligand activation of the androgen receptor (AR). Sensitization of the androgenic response by multifunctional growth factor signaling pathways is one of the mechanisms via which AR contributes to the emergence of androgen-independent prostate tumors. The ability of AR to cross-talk with key growth factor signaling events toward the regulation of cell cycle, apoptosis, and differentiation outcomes in prostate cancer cells is established. In this paper, we review the functional interaction between AR and an array of growth factor signal transduction events (including epidermal growth factor; fibroblast growth factor; IGF1; vascular endothelial growth factor; transforming growth factor-beta) in prostate tumors. The significance of this derailed cross-talk between androgens and key signaling networks in prostate cancer progression and its value as a therapeutic forum targeting androgen-independent metastatic prostate cancer is discussed.

Prohibitin and cofilin are intracellular effectors of transforming growth factor beta signaling in human prostate cancer cells

A proteomic analysis was pursued to identify new signaling effectors of transforming growth factor beta1 (TGF-beta1) that serve as potential intracellular effectors of its apoptotic action in human prostate cancer cells. The androgen-sensitive and TGF-beta-responsive human prostate cancer cells, LNCaP T beta RII, were used as in vitro model. In response to TGF-beta, significant posttranslational changes in two proteins temporally preceded apoptotic cell death. TGF-beta mediated the nuclear export of prohibitin, a protein involved in androgen-regulated prostate growth, to the cytosol in the LNCaP T beta RII cells. Cofilin, a protein involved in actin depolymerization, cell motility, and apoptosis, was found to undergo mitochondrial translocation in response to TGF-beta before cytochrome c release. Loss-of-function approaches (small interfering RNA) to silence prohibitin expression revealed a modest decrease in the apoptotic response to TGF-beta and a significant suppression in TGF-beta-induced cell migration. Silencing Smad4 showed that the cellular localization changes associated with prohibitin and cofilin action in response to TGF-beta are independent of Smad4 intracellular signaling.

Effects of long-term castration on the smooth muscle cell phenotype of the rat ventral prostate

Smooth muscle (SM) is an important component of the prostatic stroma. We previously showed that, despite extensive morphologic changes, smooth muscle cells (SMCs) of the rat ventral prostate preserve some differentiation markers 21 days after castration. In the present study, we investigated whether the expression of SMC markers is preserved in the rat ventral prostate after long-term castration. Adult Wistar rats were castrated and sacrificed 100 days after surgery. The ventral prostates were processed for histology, stereology, immunocytochemistry (SM alpha-actin and SM-myosin heavy chain [MHC]), transmission electron microscopy (TEM), and reverse transcription polymerase chain reaction (smoothelin, sm22, and calponin). The prostates of castrated rats showed significant weight reduction, corresponding to only 5.6% of the control. Stereology showed that SMCs occupied the same proportion of the prostate volume but suffered a significant reduction in absolute volume (5.5% of control). The SMCs were retracted and showed spinous outlines. TEM revealed the presence of an abundant myofibrillar component, dense plaques, and an external lamina in these cells. SMCs were reactive to antibodies against SM alpha-actin and SM-MHC and expressed mRNA for smoothelin, sm22, and calponin. The results confirmed that rat prostatic SMCs are affected by androgen deprivation. Although showing marked phenotypic changes, these cells expressed SMC markers at the protein (SM alpha-actin and SM-MHC) and mRNA (smoothelin, sm22, and calponin) levels. These observations support the idea that SMCs may modulate their phenotypes (contractile vs synthetic) without changing their differentiation states.

Smoothelin in vascular smooth muscle cells

Smoothelin-A and -B have only been found in fully differentiated contractile smooth muscle cells. They are increasingly used to monitor the smooth muscle cell differentiation process to a contractile or synthetic phenotype. Vascular-specific smoothelin-B is the first smooth muscle cell marker that disappears when vascular tissues are compromised, for example, in atherosclerosis or restenosis. Recently obtained data show that smoothelin deficiency results in a considerable loss of contractile potential and hence in impaired smooth muscle function and suggest that smoothelins are part of the contractile apparatus.

Transforming growth factor-beta in cancer and metastasis

Transforming growth factor-beta (TGF-beta) is a multifunctional regulatory polypeptide that is the prototypical member of a large family of cytokines that controls many aspects of cellular function, including cellular proliferation, differentiation, migration, apoptosis, adhesion, angiogenesis, immune surveillance, and survival. The actions of TGF-beta are dependent on several factors including cell type, growth conditions, and the presence of other polypeptide growth factors. One of the biological effects of TGF-beta is the inhibition of proliferation of most normal epithelial cells using an autocrine mechanism of action, and this suggests a tumor suppressor role for TGF-beta. Loss of autocrine TGF-beta activity and/or responsiveness to exogenous TGF-beta appears to provide some epithelial cells with a growth advantage leading to malignant progression. This suggests a pro-oncogenic role for TGF-beta in addition to its tumor suppressor role. During the early phase of epithelial tumorigenesis, TGF-beta inhibits primary tumor development and growth by inducing cell cycle arrest and apoptosis. In late stages of tumor progression when tumor cells become resistant to growth inhibition by TGF-beta due to inactivation of the TGF-beta signaling pathway or aberrant regulation of the cell cycle, the role of TGF-beta becomes one of tumor promotion. Resistance to TGF-beta-mediated inhibition of proliferation is frequently observed in multiple human cancers, as are various alterations in the complex TGF-beta signaling and cell cycle pathways. TGF-beta can exert effects on tumor and stromal cells as well as alter the responsiveness of tumor cells to TGF-beta to stimulate invasion, angiogenesis, and metastasis, and to inhibit immune surveillance. Because of the dual role of TGF-beta as a tumor suppressor and pro-oncogenic factor, members of the TGF-beta signaling pathway are being considered as predictive biomarkers for progressive tumorigenesis, as well as molecular targets for prevention and treatment of cancer and metastasis.

Testosterone effect on immature prostate gland development associated with suppression of transforming growth factor-β

The aim of this study was to evaluate the effect of testosterone treatment on the pattern of prostate cell proliferation and differentiation and their correlation with the expression of transforming growth factor-beta (TGF-beta). Prostate gland development was compared in intact immature dogs with one-month testosterone-treated immature dogs. Testosterone treatment resulted in a tenfold increase in prostate gland weight compared to untreated dogs, with a typical organization of the gland into a structure similar to that observed in mature dogs. The narrow acini which contain flat basal cells in immature glands were transformed into tubuloacinar structures containing columnar secretory cells and basal cells. The stromal compartments showed an increase in the muscular component as evidenced by the high reactivity to alpha-actin with no remarkable changes in the vimentin expression. In addition, testosterone treatment induced a significant reduction in the proliferation capacity of stromal cells but with no noticeable changes in the proliferation pattern of epithelial cells. These changes in the prostate are associated with a twofold decrease in TGF-beta mRNA expression as assessed by Real-Time PCR. However, the immunolocalization of TGF-beta was shifted slightly from the epithelial cells in untreated animals to the stromal cells of treated animals. Based on these results it appears that testosterone acts to coordinate prostatic cell proliferation and differentiation and direct their organization into a structure resembling that of the mature gland. The testosterone regulation of the prostate gland appears to involve the regulation of TGF-beta gene expression.

Pygeum africanum extract inhibits proliferation of human cultured prostatic fibroblasts and myofibroblasts

OBJECTIVE

To investigate the effect of Pygeum africanum (PA) extract on the proliferation of cultured human prostatic myofibroblasts and fibroblasts; this extract is used for treating urinary disorders associated with benign prostatic hyperplasia (BPH).

MATERIALS AND METHODS

Primary cultures of prostatic stromal cells were obtained from histologically confirmed human BPH by enzymatic digestion. Cell proliferation was measured by 5-bromo2'-deoxy-uridine (BrdU) incorporation assays, and cytotoxicity by luminescent quantification of adenylate kinase activity.

RESULTS

Cultured cells were labelled by an anti-vimentin antibody, and most of them by an alpha-smooth-muscle-actin antibody, revealing the presence of fibroblasts and myofibroblasts. BrdU incorporation tests showed that proliferation of cultured human stromal cells, stimulated by fetal calf serum, by basic fibroblast growth factor and by epidermal growth factor, was dose-dependently inhibited by PA extract (5-100 microg/mL). Except at 100 microg/mL, no acute cytotoxicity of the extract was detected after 24 h of culture. Similarly, the extract dose-dependently inhibited the proliferation of Madin-Darby canine kidney epithelial cells, but to a lesser extent; whatever the dose of extract, no acute toxicity was evident on this cell line.

CONCLUSION

PA extract inhibits the proliferation of cultured human prostatic myofibroblasts and fibroblasts. We propose that cultured human prostatic cells offer a reliable model for preclinical screening of therapeutic agents, and to study the mechanisms underlying the inhibition of proliferation.

Development of a cell-isolation method for human prostatic smooth muscle cells based on cell type-specific activation of the SM22 gene promoter

OBJECTIVE

To separate smooth muscle cells (SMCs) from fibroblasts in cultured human prostatic stromal cells (PrSCs) by characterizing the SM22 promoter as a prostatic SMC-specific gene promoter, and to investigate its use for a promoter-based cell-sorting method, as SMCs are critical for stromal function and the pathological changes in the development of benign prostatic hyperplasia.

MATERIALS AND METHODS

Human PrSCs were cultured in SMC-selective medium or standard medium, respectively, to obtain typical cultures of SMCs and fibroblasts. SM22 promoter activity and specificity were analysed by luciferase reporter-gene assay. A dual-colour vector was constructed with the expression of the red fluorescent protein (RFP) under the control of the 1.4 kb SMC-specific SM22 promoter, and the expression of the green fluorescent protein (GFP) under cytomegalovirus promoter. Fluorescence-activated cell sorting (FACS) was used to isolate and enrich GFP+/RFP+ and GFP+/RFP- cells. Cell phenotype was confirmed by reverse transcription-polymerase chain reaction and immunofluorescence.

RESULTS

The 1.4 kb SM22 promoter activity was much higher in PrSCs cultured in SMC-selective medium. Immunofluorescence staining and merged fluorescence microscopy ensured that SM22 promoter-driven GFP positive cells were SMCs. After transfection of the dual-colour vector into PrSCs, GFP+/RFP+ cells (SMCs) and GFP+/RFP- cells (fibroblasts) were isolated by FACS. The phenotype of FACS-enriched SMCs and fibroblasts was confirmed.

CONCLUSION

These results indicate that the 1.4 kb SM22 promoter is specific for prostatic SMCs. This dual-colour vector could be a useful tool for separating living SMCs from fibroblasts using FACS.

Opposing actions of TGFbeta1 and FGF2 on growth, differentiation and extracellular matrix accumulation in prostatic stromal cells

TGFbeta 1 and FGF2 are autocrine growth factors in prostatic stroma and are elevated in benign prostatic hyperplasia (BPH), a disease characterized by enlargement of the stromal compartment of the prostate. TGFbeta1 has a biphasic effect on proliferation of prostatic stromal cells, inducing proliferation at low doses (< 1 ng/ml), but inhibiting growth above 1 ng/ml. This study investigated the role of TGFP 1 and FGF2 on growth factor bioavailability and extracellular matrix (ECM) accumulation synthesis in cultured prostatic stromal cells. Real-Time-PCR showed that TGFbeta1 expression is auto-inductive, whereas FGF2 is auto-repressive. FGF2 also induced TGFbeta1 secretion in the absence of increased TGFbeta1 mRNA expression. TGFbeta1 and FGF2 have opposing actions on Type 1 collagen expression, a finding confirmed by Western blotting. The bioavailability of TGFbeta1 regulated by FGF2 may represent part of a negative feedback mechanism controlling stromal growth, differentiation and ECM. Dysregulation of this pathway in favour of TGFbeta1 bioactivity may exacerbate BPH.

Specialized stromal tumors of the prostate: a clinicopathologic study of 50 cases

Specialized stromal tumors of the prostate encompass stromal sarcoma and stromal tumors of uncertain malignant potential (STUMP). As a result of their relative rarity and lack of long-term follow-up, the prognosis of STUMP is unclear. We studied 50 cases of STUMP and stromal sarcoma with regard to their clinical presentation and follow-up. Patients ranged in age from 27 to 83 years (mean 58 years). The major presenting signs and symptoms were urinary obstructive symptoms (n=25), abnormal digital rectal exam (n=15), hematuria (n=7), hematospermia (n=1), and rectal dysfunction/fullness (n=3). An elevated prostate-specific antigen was either the sole or a compounding rationale for initial urologic examination and prostate biopsy in a subgroup of patients (n=11). The histology in the 36 cases of STUMP not associated with sarcoma were as follows: 25 composed of stroma with scattered cytologically atypical cells associated with benign glands; 8 resembling glandular-stromal hyperplasia but with hypercellular stroma; 6 with extensive myxoid stroma; and 1 with phyllodes pattern. Four of these cases had mixed patterns. Seven cases of STUMP were associated with sarcoma, either concurrently or subsequently. In another 7 cases, pure sarcomas were encountered: 3 low grade (LG) and 4 high grade (HG). In 19 STUMPs, the location of the lesion was determinable: 10 cases arose in the peripheral zone, 7 cases were located in the transition zone, and 2 cases seemed to involve both zones. In 3 of these cases, tumors were adherent to the rectum at the time of resection. There was no evidence of progression of disease for 14 STUMPs after biopsy, TUR, or enucleation where follow-up ranged from 0.3 to 14 years (mean 4.9 years). Five cases of STUMP showed local tumor growth: 1 case increased in size from 6 to 7.5 cm in 3 years and 4 cases recurred frequently necessitating multiple TURs of the prostate (n=2, n=3, n=3, n=3) over 1.1, 2, 7, and 8 years, respectively. Fourteen patients with STUMP underwent radical prostatectomy (RP) soon after diagnosis; of these, 12 were organ confined where the tumor size ranged from 0.7 to 7.5 cm (mean 2.7 cm); 2 cases with a history of a 28 g TUR and a 275 g enucleation showed no residual tumor in the RP specimen. Three cases were lost to follow-up. The histologic subtypes of STUMP did not correlate with the clinical behavior or likelihood of being associated with sarcoma. Two of the LG sarcomas locally invaded around the seminal vesicle, yet all of the LG sarcomas with follow-up were free of disease at 3, 13, 24, 25, 30, and 36 months. Of the 6 HG sarcomas with follow-up, 3 were free of disease at 3, 17, and 72 months. One man was alive with metastasis to the lung 10 months after RP, 1 man was alive at 280 months with multiple metastases, and another died of disease at 115 months. STUMPs can recur frequently, occur at a young age, often involve the peripheral zone where they can be adherent to the rectum requiring its removal, and can be associated with stromal sarcoma. Although STUMPs can be histologically misdiagnosed as nodular hyperplasia, it is important to recognize that these are neoplasms with unique local morbidity and malignant potential. Whereas LG stromal sarcomas can locally invade, HG sarcomas can metastasize and lead to death.

Sex steroids modulate α1-adrenoceptor-stimulated Ca2+ elevation in human cultured prostatic stromal cells

BACKGROUND

Benign prostatic hyperplasia is an age- and androgen-dependent condition of urethral compression caused by prostatic contractility and glandular enlargement. In this study we investigate whether testosterone, dihydrotestosterone and estradiol modulate the ability of human cultured prostatic stromal cells (HCPSCs) to respond to the adrenoceptor agonists, noradrenaline (30 microM) and phenylephrine (100 microM), the protein kinase C activating phorbol ester, phorbol diacetate (PDA, 10 microM), and the L-type Ca(2+) channel activator, (-)-Bay K8644 (Bay K, 10 microM) with elevations of intracellular Ca(2+) ([Ca(2+)](i)).

METHODS

Cells were loaded with the Ca(2+) sensitive fluorophore, FURA-2AM (10 microM) and changes in intracellular Ca(2+) determined before and 8-12 min after ligand addition.

RESULTS

Compared to steroid-free (SF) controls, the incubation of HCPSC with testosterone (30 and 300 pM) significantly increased responses to both noradrenaline and phenylephrine. Responses to Bay K were significantly reduced between 30 nM to 300 pM but responses to PDA were not greatly affected. Compared to SF the addition of estradiol (E(2), 100 pM) did not affect responses to phenylephrine. The concomitant addition of dihydrotestosterone (DHT) and E(2) (to give ratios from 1:1 to 1,000:1) elevated the responses to noradrenaline and phenylephrine at the extreme ranges. Responses to PDA and Bay K generally increased as DHT:E(2) approached unity.

CONCLUSIONS

These results indicate that sex steroids modulate the activities of HCPSCs through the regulation of both receptors and signal transduction processes.

Current models of human prostate contractility

1. The human prostate is a compact gland contributing to seminal fluid. With increasing age, most humans will develop benign prostatic hyperplasia, a condition of prostatic enlargement and contractility that leads to occlusion of the urethra. Over many years, investigators have used a variety of animal and cell culture models to elucidate some of the contractile and proliferative mechanisms that may be associated with the development of this condition. 2. This review briefly assesses the current state of knowledge of the mechanisms underlying human prostatic contractility and compares it with that of animal and cell culture models. It is not intended as a comprehensive methodological review, nor is it intended to indicate our preferences for either model. Our aim is to correlate findings from animal and cell culture models with the current understanding of human prostate contractility. 3. We hope that the present review will increase awareness of the suitability of the current models in developing our understanding of benign prostatic hyperplasia.

Prostate epithelial cell differentiation and its relevance to the understanding of prostate cancer therapies

Prostate cancer is the most common malignancy in males in the western world. However, little is known about its origin and development. This review highlights the biology of the normal prostate gland and the differentiation of basal epithelial cells to a secretory phenotype. Alterations in this differentiation process leading to cancer and androgen-independent disease are discussed, as well as a full characterization of prostate epithelial cells. A full understanding of the origin and characteristics of prostate cancer epithelial cells will be important if we are to develop therapeutic strategies to combat the heterogeneous nature of this disease.

Effects of 5 alpha reductase inhibitors on androgen-dependent human prostatic carcinoma cells

PURPOSE

To investigate the effects of MK906, a selective 5 alpha reductase (5alphaR) type 2 (5alphaR2) inhibitor, and of MK386, a specific 5alphaR1 inhibitor, on the cellular proliferation of androgen-dependent human prostatic cancer (PCa) cells in cultures of cells derived from bioptic and surgical tissues.

METHODS

In this study we tested the effects of MK906 and MK386 in 30 cultures derived from PCa, 6 from PIN and 10 from benign prostatic hyperplasia specimens.

RESULTS

Prostate primary cultures under short-term conditions (with <4 subcultures) represent a mixture of epithelial and stromal cells. Epithelial cells require testosterone (T) for optimal growth, but were not able to grow in the presence of T under long-term conditions even if DHT was able to induce cellular proliferation to a similar extent in both conditions, suggesting that 5alphaR can be lost in long-term cultures. Therefore, our studies were performed under short-term conditions. Both 5alphaR inhibitors decreased cell proliferation significantly and dose-dependently in all the samples tested. MK906 was more efficient than MK386 in 7 out of 10 cultures derived from BPH tissues, in 4 out of 6 cultures derived from PIN and in 18 out of 30 cultures derived from PCa. In 3 out of 10 BPH, in 2 out of 6 PIN and in 5 out of 30 PCa-derived cultures, both inhibitors presented similar efficacy, whereas in 1 out of 10 BPH and 7 out of 30 PCa-derived cultures MK386 was more efficient than MK906. In addition, MK386 was more efficient than MK906 in 4 out of 15 non-metastatic PCa and 2 out of 7 metastatic PCa-derived cultures.

CONCLUSIONS

Considering that 5alphaR1 (responsible primarily for androgenic catabolism) is mostly expressed in epithelial cells and that 5alphaR2 (responsible for local DHT synthesis and release) is expressed in the stromal cells (which provides several paracrine growth factors and DHT itself to the epithelial cells), our experiments suggest that the inhibition of both 5alphaR1 and 5alphaR2 by MK386 and MK906, respectively, may have therapeutic potential in order to reduce the growth and progression of human prostatic cancers, through the inhibition of autocrine or paracrine mechanisms involving the stromal cell compartment. In addition, some effects of 5alphaR inhibitors could be mediated by estrogens, which are synthesized by the aromatase enzyme present in the epithelial cells. These aspects could be considered in order to improve the therapeutical management of PCa and for future clinical trials.

Intracellular Ca2+ regulation in a human prostate stromal cell culture

AIMS

Prostate stromal cell cultures are used in vitro to study the cellular pathophysiology of benign prostatic hyperplasia (BPH), but their functional properties are poorly understood. This study characterized intracellular Ca2+ ([Ca2+]i) regulation in a cultured cell line in comparison to freshly isolated cells, as a background to understanding contractile regulation and cellular proliferation in this tissue.

METHODS

Prostate stromal cells were isolated from either PrS6 cell cultures, with an extended life span by transfection with the SV40 T-antigen, tsA58-U19, or freshly obtained transition zone prostate samples, primary cells. [Ca2+]i was measured in vitro with the indicator Fura-2 by epifluorescence microscopy.

RESULTS

Phenylephrine, high-K+, and caffeine induced Ca2+-transients in primary cells (resting [Ca2+]i 94 +/- 8 nM, n = 29; peak 193 +/- 26 nM, n = 19). In PrS6 cells resting [Ca2+]i was 96 +/- 8 nM (n = 78) and in 34 of these 78 cells, 30 microM phenylephrine increased [Ca2+]i to 296 +/- 28 nM. 5-methyl-urapidil (10-30 microM) inhibited this response in 10 of 16 cells. Spontaneous Ca2+-transients were also observed in 91% of phenylephrine-responsive cells, but in only 20% of non-responsive cells (P < 0.01). Ca2+-transients were also induced by high-K+ solution, and 20 mM caffeine. The latter abolished the response to subsequent phenylephrine application. Depletion of intracellular Ca2+ stores by caffeine or restoration from a Ca2+-free superfusate caused a substantial rise of [Ca2+]i.

CONCLUSIONS

PrS6 prostate stromal cells express functional alpha1-adrenoceptors associated with spontaneous intracellular Ca2+-transients. They exhibit functional Ca2+ channels, intracellular Ca2+ stores, and Ca2+ entry induced by store depletion. Stromal cultures can therefore be used to characterize the cellular physiology of prostate stromal cell contraction and proliferation.

Smooth muscle cell behavior in the ventral prostate of castrated rats

Smooth muscle cells (SMC) play roles in prostatic development and function. The cells also respond to tissue injury and hormonal variations, alternating between a fully differentiated and contractile phenotype and a dedifferentiated synthetic or secretory phenotype. However, the phenotypic changes in SMC after androgen deprivation have not yet been described. The ventral prostate of control and castrated rats was processed for routine histology, immunocytochemistry, reverse transcriptase polymerase chain reaction (RT-PCR), and scanning electron microscopy (SEM). The maintenance of SMC phenotype was confirmed by immunocytochemistry and by RT-PCR. Stereological analyses were done to define the relative and absolute volume of the SMC. SMC were elongated and flattened against the epithelium. After castration, the cells shortened concomitantly with pleating of the cell surface, leading to a spinous aspect. SEM showed that the smooth surface of SMC became progressively folded. Immunocytochemistry demonstrated both smooth muscle myosin heavy chain and smooth muscle alpha-actin in the prostatic SMC 21 days after castration, whereas RT-PCR amplified the message for smoothelin. Stereological analysis showed an increase in the relative volume of SMC in relation to the whole gland and the stroma. A decrease in the absolute volume of SMC occurred only within the first 7 days after castration and remained unchanged thereafter. The prostatic SMC are affected by the absence of androgens and there is a critical transition point during the first week in which the total volume occupied by SMC diminished. The remaining SMC showed a marked phenotypical change. These findings indicate that ventral prostate SMC maintain their differentiated phenotype after castration. The alterations in SMC behavior correlate with general stromal modifications taking place after castration.

Regulation of interleukin-6-mediated PI3K activation and neuroendocrine differentiation by androgen signaling in prostate cancer LNCaP cells

BACKGROUND

Neuroendocrine (NE) differentiation in prostate cancer has been suggested to be one of the early events in the development of androgen independence. In the human prostate cancer LNCaP cell line, treatment with interleukin-6 (IL-6) induces NE-like differentiation, which is similar to the phenomena observed in advanced stages of prostate cancer progression. In this study, we investigate how androgen plays a role in IL-6-mediated NE differentiation in LNCaP cell line.

METHODS

Western blot, co-immunoprecipitation (co-IP), and GST pull-down assays were performed to detect the protein expression and protein-protein interaction. PI3K kinase assay was used to measure PI3K activity.

RESULTS

Addition of androgen blocks IL-6-mediated PI3K activation and NE differentiation in LNCaP cells. In vivo and in vitro protein interaction assays suggested that androgen receptor (AR) can directly interact with IL-6 transducer gp130. In addition, androgen treatment enhances the interaction between AR and gp130, interrupts the IL-6-induced gp130-mediated PI3K activation, which may lead to inhibition of IL-6-mediated NE differentiation in LNCaP cells.

CONCLUSIONS

Our results suggest androgen and AR can regulate IL-6-mediated LNCaP cell NE differentiation via directly modulating the IL-6-PI3K pathway.

Relationship between upregulated oestrogen receptors and expression of growth factors in cultured, human, prostatic stromal cells exposed to estradiol or dihydrotestosterone

This study investigated the hypothesis that, in benign prostatic hyperplasia (BPH), upregulated oestrogen receptors (ER) and the action of androgens differentially regulate expression of stromal growth factors. Eight human prostatic stromal cell strains were subjected to a procedure to upregulate their ER by exposing them to 1 micromol 17beta-estradiol for 10 days followed by passage and growth in the absence of steroids. Four of the cell strains instead received 100 nmol dihydrotestosterone for 48 h. Immunoexpression of ERalpha, AR and six growth factors was quantified by flow cytometry in each case. Expression of ERalpha was significantly increased in six of eight cell strains. Expressions of six growth factors (FGF-2, FGF-7, IGF-1, TGF-beta1 NGF and e NOS) were elevated but only for FGF-7 was it significant. There was a significant positive correlation between the change in ERalpha and the change in FGF-2 and FGF-7, but not the other growth factors. Exposure to dihydrotestosterone reduced expression of ERalpha and all six growth factors, compared with oestrogen-treated cells but not significantly. It is concluded that upregulated ERalpha in prostatic stroma may have a greater modulating influence on synthesis of certain growth factors than the direct action of androgens and, by enhancing synthesis of FGF-2 and FGF-7, could play a significant role in the development of BPH.

Age-induced apoptosis in the male genital tract of the mouse

We have examined the effects of ageing on the increase in apoptotic cells numbers in the male genital tract of the house mouse (Mus musculus). We have found that not all organs have the same response. There is an induction of apoptosis in both the epididymis and ventral prostate. However, seminal vesicles and other prostatic lobes remain unaffected. Apoptosis was assessed by several methods: TUNEL, detection of the active fragment of caspase-3 and the pattern of DNA fragmentation on agarose gels. This increase in apoptosis is related to the fall in testosterone levels, although there is only a partial decrease in androgen receptor (AR). AR is still present in all tissues and only moderately reduced in the epididymis and ventral prostate. A more intense increase of lipofuscin granules, which may be indicative of oxidative stress, occurred in these tissues. Finally, testosterone supplementation reverses the changes (both in apoptosis and lipofuscin content in the tissue), suggesting a role of androgens in these processes.

Modulation of phenotype of human prostatic stromal cells by transforming growth factor-betas

BACKGROUND

We investigated the effects of transforming growth factor (TGF)-betas on morphological and receptor phenotypes, as well as proliferation of four currently established human prostatic myofibroblast cell lines and one commercially available prostatic stromal cell line.

METHODS

The effects of TGF-betas on morphological changes and proliferation of the cells were studied by immunohistochemistry and bromodeoxyuridine assay, respectively. The expression of alpha 1-receptor subtypes was measured by real time quantitative reverse transcription-polymerase chain reaction (RT-PCR) and the radioligand binding assay for the receptors was also performed.

RESULTS

TGF-betas 1, 2, and 3 induced expression of desmin and myosin of cells of the established cell lines, and significantly inhibited their growth. The alpha 1a-receptor was expressed only in the commercially available cell line and alpha 1b and 1d, in all cell lines. TGF-beta 1 suppressed the expression of all three subtypes of the alpha 1-receptor. The binding sites of cells of all the cell lines were reduced by treatment with this growth factor.

CONCLUSIONS

TGF-betas may induce human prostatic stromal cells to express the smooth muscle phenotype and inhibited their growth. However, the growth factor reduced the binding sites of the receptor and suppressed mRNA expression of its subtypes, suggesting that morphological and receptor phenotypes may be regulated via more than one pathway by TGF-beta(s).

Cellular and molecular biology of the prostate: stem cell biology

The normal prostate shows a high degree of cellular organization. The basal layer is populated by prostate epithelial stem cells and a population of transiently proliferating/amplifying (TP/A) cells intermediate to the stem cells and fully differentiated cells. The luminal layer is composed of fully differentiated prostate epithelial cells. Neuroendocrine cells are scattered throughout the gland. This organization is also seen in prostate cancer, where the tumor cell origin (cancer stem cells) can be traced to a normal cell type by characteristic keratin expression patterns. Basal cells showed strong expression of K-[keratin]5, but they were only weakly positive for K18. Luminal cells strongly expressed K18. A subpopulation of basal cells coexpressed K5 and K14. These keratin expression patterns changed with the degree of cell differentiation as well as location. The least differentiated stem cells in the basal layer were positive for K5 and K14, with weak expression for K18. Intermediate stages of differentiation were identified by expression of K5 and K18. Neuroendocrine cells also expressed K5 as well as typical neuroendocrine cell markers (eg, chromogranin A). Evidence supporting the hypothesis that prostate cancer arises from malignant transformation of intermediate stem cells included the presence in prostate cancers of keratin patterns associated with the intermediate stages of differentiation, androgen independence of both prostate cancers and intermediate stem cells, and expression of c-met by both the TP/A intermediate stem cells and tumor cells.

Dual regulation of proliferation and growth arrest in prostatic stromal cells by transforming growth factor-beta1

In a preliminary study, we observed that TGF-beta1 induced both proliferation and growth arrest in prostatic stromal cells, depending on the concentration of TGF-beta1 used in the culture medium. In this study, we explored possible mechanisms of this dual effect of TGF-beta. Primary cultures of prostatic stromal cells, established from clinical surgical specimens and treated with low doses of TGF-beta1 (0.001-0.01 ng/ml), resulted in an increase in cell proliferation. The addition of neutralizing antibody against platelet-derived growth factor (PDGF)-BB, but not anti-PDGF-AA, abrogated this stimulatory effect of TGF-beta1. TGF-beta1 treatment resulted in a dose-related increase in PDGF-BB production as measured by ELISA. Cells underwent growth arrest at high concentrations of TGF-beta1 (1.0 and 10 ng/ml). An inhibitor of cyclin-dependent kinase (cdk), p15INK4b, was up-regulated at both transcript and protein levels in these cultures by TGF-beta1 in a dose-related manner as determined by RT-PCR and Western blot analysis. The transcript, but not the protein, for another cdk inhibitor, p21Cip1, was up-regulated with treatment of TGF-beta1 to these cells. Levels of other cdk inhibitors, such as p16INK4a and p27Kip1, were constitutively expressed in prostatic stromal cells and were not significantly affected by TGF-beta1 treatment. Finally, the growth arrest effect of TGF-beta1 was abrogated when antisense oligonucleotides to p15INH4b, but not p21Cip1, were added to the culture medium. These data indicate that the dual effect of TGF-beta1 is mediated, at least, by up-regulation of PDGF-BB and p15INK4b, respectively.

The role of dihydrotestosterone in benign prostatic hyperplasia

This article examines the role of the androgen dihydrotestosterone (DHT) in the healthy and diseased prostate and considers the implications of the data on DHT for therapeutic approaches to benign prostatic hyperplasia (BPH). Development and maintenance of the normal prostate, as well as development of BPH, depend on a functional androgen-signaling axis, components of which include: (1) testosterone synthesis in the testes and adrenal glands; (2) conversion of testosterone to DHT; (3) transport of DHT to target tissues; and (4) binding of DHT to the androgen receptor with consequent modulation of genes. DHT plays a beneficial role in the developing prostate but it can be detrimental in the adult prostate in that it causes pathologic prostate growth. The role of DHT in other adult tissues is uncertain. DHT has not been shown to perform beneficial functions unique from testosterone in the adult male, and it is believed that its fundamental effect is to amplify testosterone's weaker hormonal signal. Increased understanding of the cellular mechanisms by which the androgen-signaling axis functions has led to advances in treatment for prostate disease. In BPH, the 5alpha-reductase inhibitors--the only class of therapy to act at the pathophysiologic substrate of the disease--arrest the disease process, reduce prostate volume, improve symptoms, and reduce the risk of acute urinary retention and BPH-related surgery. The availability of dutasteride, the first dual (Type 1/Type 2) 5alpha-reductase inhibitor, offers the opportunity for rapid and consistent inhibition of DHT.

Dedifferentiation of stromal smooth muscle as a factor in prostate carcinogenesis

We had earlier established an animal model of prostate carcinogenesis using a combination of testosterone (T) and 17beta-estradiol benzoate (E2) on Noble rats (Wang and Wong, 1998). In the present study we examined the changes in a number of smooth muscle differentiation markers including smooth muscle alpha-actin and myosin, vinculin, desmin, laminin and vimentin as well as changes in fine structure by electron microscopy. Our immunohistochemical (IHC) studies revealed that smooth muscle cells (SMCs) subjacent to dysplastic (precancerous) sites and carcinoma usually exhibited a preferential loss of myosin, desmin and laminin. However, the expression of alpha-actin and vinculin appeared to be more persistent in most dysplastic or neoplastic sites. The study reaffirmed our earlier observation that there was a concurrent dedifferentiation of surrounding SMCs during the development and progression of prostate carcinogenesis. The structural study revealed that SMC subjacent to epithelial dysplasia displayed a spectrum of derangements. These included the loosening of muscular layers with SMC characterized by their highly irregular external contours with numerous spine-like cytoplasmic projections. There was also a reduction in density of myofilaments and presence of many enlarged caveolae in muscle cells. Additionally, focal discontinuity or disruptions of muscular layer were often observed together with an increase in abundance of fibrous connective tissue. Moreover, the amount of smooth muscle appeared to be inversely correlated with the histologic grade of prostate tumors. In most instances, SMCs were totally absent in the moderately or poorly differentiated tumors and in metastatic tumors in the lung and the small intestine. Stromal muscular deformity was associated with concurrent changes in epithelial cells. Dysplastic epithelial cells were characterized by a reduction in abundance of secretory organelles such as reduction in size of Golgi apparatus, paucity of granular endoplasmic reticulum and secretory vesicles. The nuclei showed typical deformity characterized by deep nuclear membrane foldings. The basal lamina of dysplastic or tumor cells was present although focal structural abnormalities such as reduplication, disruption and smearing were sometimes observed. The present data indicate that derangements of epithelial cells during prostate carcinogenesis are associated with a reduction or dedifferentiation of stromal SMCs. Our results lend support to the hypothesis that transformed epithelium is incapable of maintaining normal differentiation of adjacent muscle. In turn, abnormal stromal, resulting from dedifferentiation or reduction of SMC, may lead to loss of stromal control over epithelial proliferation and differentiation. Consequently, a loss of differentiation in both epithelium and stromal SMCs may be critically involved in hormone-induced prostate carcinogenesis.