Prostate development requires Sonic hedgehog expressed by the urogenital sinus epithelium

Endocrine Disruption of Propylparaben in the Male Mosquitofish (Gambusia affinis): Tissue Injuries and Abnormal Gene Expressions of Hypothalamic-Pituitary-Gonadal-Liver Axis

Propylparaben (PrP) is a widely used preservative that is constantly detected in aquatic environments and poses a potential threat to aquatic ecosystems. In the present work, adult male mosquitofish were acutely (4d) and chronically (32d) exposed to environmentally and humanly realistic concentrations of PrP (0, 0.15, 6.00 and 240 μg/L), aimed to investigate the toxic effects, endocrine disruption and possible mechanisms of PrP. Histological analysis showed time- and dose-dependent manners in the morphological injuries of brain, liver and testes. Histopathological alterations in the liver were found in 4d and severe damage was identified in 32d, including hepatic sinus dilatation, cytoplasmic vacuolation, cytolysis and nuclear aggregation. Tissue impairments in the brain and testes were detected in 32d; cell cavitation, cytomorphosis and blurred cell boundaries appeared in the brain, while the testes lesions contained spermatogenic cell lesion, decreased mature seminal vesicle, sperm cells gathering, seminiferous tubules disorder and dilated intercellular space. Furthermore, delayed spermatogenesis had occurred. The transcriptional changes of 19 genes along the hypothalamus-pituitary-gonadal-liver (HPGL) axis were investigated across the three organs. The disrupted expression of genes such as Ers, Ars, Vtgs, cyp19a, star, hsd3b, hsd17b3 and shh indicated the possible abnormal steroidogenesis, estrogenic or antiandrogen effects of PrP. Overall, the present results provided evidences for the toxigenicity and endocrine disruptive effects on the male mosquitofish of chronic PrP exposure, which highlights the need for more investigations of its potential health risks.

Pathway Enrichment Analysis of Microarray Data Fom Human Penis of Diabetic and Peyronie's Patients, in Comparison with Diabetic Rat Erectile Dysfunction Models

BACKGROUND

Erectile dysfunction (ED) is a debilitating medical condition in which current treatments are minimally effective in diabetic patients due to neuropathy of the cavernous nerve, a peripheral nerve that innervates the penis. Loss of innervation causes apoptosis of penile smooth muscle, remodeling of corpora cavernosa (penile erectile tissue) morphology, and ED.

AIM

In this study, microarray and pathway analysis were used to obtain a global understanding of how signaling mechanisms are altered in diabetic patients and animal models as ED develops, in order to identify novel targets for disease management, and points of intervention for clinical therapy development.

METHODS AND OUTCOMES

Human corpora cavernosal tissue was obtained from diabetic (n = 4) and Peyronie's (control, n = 3) patients that were undergoing prosthesis implant to treat ED, and BB/WOR diabetic (n = 5) and resistant (n = 5) rats. RNA was extracted using TRIzol, DNase treated, and purified by Qiagen mini kit. Microarray was performed using the Human Gene 2.0 ST Array. (i) Alterations in patient and diabetic rat pathway signaling were examined using several analytical tools (ShinyGO, Metascape, WebGestalt, STRING) and databases, (ii) Strengths/weaknesses of the different pathway analysis tools were compared, and (iii) Comparison of human and rat (BB/WOR and Streptozotocin) pathway analysis was performed. Two technical replicates were performed. P value (FDR) < .15 was used as threshold for differential expression. FDR < 0.05 was considered significant.

RESULTS

Microarray identified 182 differentially expressed protein-coding genes. Pathway analysis revealed similar enrichments with different analytical tools. Down regulated pathways include development, tubular structure, sprouting, cell death, ischemia, angiogenesis, transcription, second messengers, and stem cell differentiation. ED patients, who have diabetes, incur significant loss of normal regulatory processes required for repair and replacement of injured corpora cavernosal tissue. Combined with loss of apoptotic regulatory mechanisms, this results in significant architectural remodeling of the corpora cavernosa, and loss of regenerative capacity in the penis.

CLINICAL TRANSLATION

This first report of microarray and pathway analysis in human corpora cavernosa, is critical for identification of novel pathways pertinent to ED and for validating animal models.

STRENGTHS AND LIMITATIONS

The analysis of tissue specific gene expression profiles provides a means of understanding drivers of disease and identifying novel pathways for clinical intervention.

CONCLUSION

Penis from diabetic ED patients lacks capacity for maintenance of corpora cavernosal architecture and regeneration, which are critical points for intervention for therapy development.

A Review of Prostate Organogenesis and a Role for iPSC-Derived Prostate Organoids to Study Prostate Development and Disease

The prostate is vulnerable to two major age-associated diseases, cancer and benign enlargement, which account for significant morbidity and mortality for men across the globe. Prostate cancer is the most common cancer reported in men, with over 1.2 million new cases diagnosed and 350,000 deaths recorded annually worldwide. Benign prostatic hyperplasia (BPH), characterised by the continuous enlargement of the adult prostate, symptomatically afflicts around 50% of men worldwide. A better understanding of the biological processes underpinning these diseases is needed to generate new treatment approaches. Developmental studies of the prostate have shed some light on the processes essential for prostate organogenesis, with many of these up- or downregulated genes expressions also observed in prostate cancer and/or BPH progression. These insights into human disease have been inferred through comparative biological studies relying primarily on rodent models. However, directly observing mechanisms of human prostate development has been more challenging due to limitations in accessing human foetal material. Induced pluripotent stem cells (iPSCs) could provide a suitable alternative as they can mimic embryonic cells, and iPSC-derived prostate organoids present a significant opportunity to study early human prostate developmental processes. In this review, we discuss the current understanding of prostate development and its relevance to prostate-associated diseases. Additionally, we detail the potential of iPSC-derived prostate organoids for studying human prostate development and disease.

Developmental expression patterns of toolkit genes in male accessory gland of Drosophila parallels those of mammalian prostate

Conservation of genetic toolkits in disparate phyla may help reveal commonalities in organ designs transcending their extreme anatomical disparities. A male accessory sexual organ in mammals, the prostate, for instance, is anatomically disparate from its analogous, phylogenetically distant counterpart – the male accessory gland (MAG) – in insects like Drosophila. It has not been ascertained if the anatomically disparate Drosophila MAG shares developmental parallels with those of the mammalian prostate. Here we show that the development of Drosophila mesoderm-derived MAG entails recruitment of similar genetic toolkits of tubular organs like that seen in endoderm-derived mammalian prostate. For instance, like mammalian prostate, Drosophila MAG morphogenesis is marked by recruitment of fibroblast growth factor receptor (FGFR) – a signalling pathway often seen recruited for tubulogenesis – starting early during its adepithelial genesis. A specialisation of the individual domains of the developing MAG tube, on the other hand, is marked by the expression of a posterior Hox gene transcription factor, Abd-B, while Hh-Dpp signalling marks its growth. Drosophila MAG, therefore, reveals the developmental design of a unitary bud-derived tube that appears to have been co-opted for the development of male accessory sexual organs across distant phylogeny and embryonic lineages.

This article has an associated First Person interview with the first author of the paper.

Summary: We show genetic toolkit conservation between Drosophila MAG and mammalian prostate may suggest a common modular developmental design.

Testosterone exposure in prenatal life disrupts epithelial nuclear morphology, smooth muscle layer pattern, and FGF10 and Shh expression in prostate

The aim of this study was to evaluate whether high levels of exogenous testosterone (T) interfere in prostate morphogenesis. Pregnant females were exposed to subcutaneous injections of T cypionate (500 μg/animal) at gestational days 20 and 22. Male and female pups were euthanized at postnatal days 1 and 15. 15-day-old males had only fibroblast growth factor 10 (FGF10) immunostaining and nuclear form factor altered by the treatment, whereas treated females (T1 and T15) had almost all analyzed parameters changed. T1 females showed an increased anogenital distance (AGD), whereas T15 females had both AGD and ovary weight increased. T1 females had a higher number of epithelial buds emerging from the urethral and vaginal epithelium. We observed ectopic prostatic tissue surrounding the vagina in both T1 and T15 females. Moreover, the ectopic acini of T15 females showed delayed luminal formation, and there was a thickening of the periacinar smooth muscle layer (SML). Finally, FGF10 immunostaining intensity decreased in both T15 male and female prostates. Indeed, Sonic hedgehog (Shh) was upregulated in T15 female prostates, whereas no difference was observed between the male groups. These data showed that exogenous T changed the nuclear morphology of prostate epithelial cells in both males and females. Surprisingly, smooth muscle hyperplasia was also observed in the ectopic female prostate. Moreover, T downregulated FGF10 in both male and female prostates. Interestingly, the results suggest that FGF10 downregulation is mediated by the upregulation of Shh in females. In conclusion, exogenous T disrupts prostate development, particularly, affecting, the female.

Androgen action in cell fate and communication during prostate development at single-cell resolution

Androgens/androgen receptor (AR)-mediated signaling pathways are essential for prostate development, morphogenesis and regeneration. Specifically, stromal AR signaling has been shown to be essential for prostatic initiation. However, the molecular mechanisms underlying AR-initiated mesenchymal-epithelial interactions in prostate development remain unclear. Here, using a newly generated mouse model, we have directly addressed the fate and role of genetically marked AR-expressing cells during embryonic prostate development. Androgen signaling-initiated signaling pathways were identified in mesenchymal niche populations at single-cell transcriptomic resolution. The dynamic cell-signaling networks regulated by stromal AR were additionally characterized in relation to prostatic epithelial bud formation. Pseudotime analyses further revealed the differentiation trajectory and fate of AR-expressing cells in both prostatic mesenchymal and epithelial cell populations. Specifically, the cellular properties of Zeb1-expressing progenitors were assessed. Selective deletion of AR signaling in a subpopulation of mesenchymal rather than epithelial cells dysregulated the expression of the master regulators and significantly impaired prostatic bud formation. These data provide novel, high-resolution evidence demonstrating the important role of mesenchymal androgen signaling in the cellular niche controlling prostate early development by initiating dynamic mesenchyme-epithelia cell interactions.

The FGF/FGFR system in the physiopathology of the prostate gland

Fibroblast growth factors (FGFs) are a family of proteins possessing paracrine, autocrine, or endocrine functions in a variety of biological processes, including embryonic development, angiogenesis, tissue homeostasis, wound repair, and cancer. Canonical FGFs bind and activate tyrosine kinase FGF receptors (FGFRs), triggering intracellular signaling cascades that mediate their biological activity. Experimental evidence indicates that FGFs play a complex role in the physiopathology of the prostate gland that ranges from essential functions during embryonic development to modulation of neoplastic transformation. The use of ligand- and receptor-deleted mouse models has highlighted the requirement for FGF signaling in the normal development of the prostate gland. In adult prostate, the maintenance of a functional FGF/FGFR signaling axis is critical for organ homeostasis and function, as its disruption leads to prostate hyperplasia and may contribute to cancer progression and metastatic dissemination. Dissection of the molecular landscape modulated by the FGF family will facilitate ongoing translational efforts directed toward prostate cancer therapy.

Hedgehog Signaling for Urogenital Organogenesis and Prostate Cancer: An Implication for the Epithelial-Mesenchyme Interaction (EMI)

Hedgehog (Hh) signaling is an essential growth factor signaling pathway especially in the regulation of epithelial-mesenchymal interactions (EMI) during the development of the urogenital organs such as the bladder and the external genitalia (EXG). The Hh ligands are often expressed in the epithelia, affecting the surrounding mesenchyme, and thus constituting a form of paracrine signaling. The development of the urogenital organ, therefore, provides an intriguing opportunity to study EMI and its relationship with other pathways, such as hormonal signaling. Cellular interactions of prostate cancer (PCa) with its neighboring tissue is also noteworthy. The local microenvironment, including the bone metastatic site, can release cellular signals which can affect the malignant tumors, and vice versa. Thus, it is necessary to compare possible similarities and divergences in Hh signaling functions and its interaction with other local growth factors, such as BMP (bone morphogenetic protein) between organogenesis and tumorigenesis. Additionally, this review will discuss two pertinent research aspects of Hh signaling: (1) the potential signaling crosstalk between Hh and androgen signaling; and (2) the effect of signaling between the epithelia and the mesenchyme on the status of the basement membrane with extracellular matrix structures located on the epithelial-mesenchymal interface.

Hedgehog Signaling: An Achilles' Heel in Cancer

Hedgehog signaling pathway originally identified in the fruit fly Drosophila is an evolutionarily conserved signaling mechanism with crucial roles in embryogenesis, growth and patterning. It exerts its biological effect through a signaling mechanism that terminates at glioma-associated oncogene (GLI) transcription factors which alternate between activator and repressor forms and mediate various responses. The important components of the pathway include the hedgehog ligands (SHH), the Patched (PTCH) receptor, Smoothened (SMO), Suppressor of Fused (SuFu) and GLI transcription factors. Activating or inactivating mutations in key genes cause uncontrolled activation of the pathway in a ligand independent manner. The ligand-dependent aberrant activation of the hedgehog pathway causing overexpression of hedgehog pathway components and its target genes occurs in autocrine as well as paracrine fashion. In adults, aberrant activation of hedgehog signaling has been linked to birth defects and multiple solid cancers. In this review, we assimilate data from recent studies to understand the mechanism of functioning of the hedgehog signaling pathway, role in cancer, its association in various solid malignancies and the current strategies being used to target this pathway for cancer treatment.

A pivotal role of androgen signaling in Notch-responsive cells in prostate development, maturation, and regeneration

Androgen signaling is essential for prostate development, morphogenesis, and regeneration. Emerging evidence also indicates a regulatory role of Notch signaling in prostate development, differentiation, and growth. However, the collaborative regulatory mechanisms of androgen and Notch signaling during prostate development, growth, and regeneration are largely unknown. Hairy and Enhancer of Split 1 (Hes1) is a transcriptional regulator of Notch signaling pathways, and its expression is responsive to Notch signaling. Hes1-expressing cells have been shown to possess the regenerative capability to repopulate a variety of adult tissues. In this study, we developed new mouse models to directly assess the role of the androgen receptor in prostatic Hes1-expressing cells. Selective deletion of AR expression in embryonic Hes1-expressing cells impeded early prostate development both in vivo and in tissue xenograft experiments. Prepubescent deletion of AR expression in Hes1-expressing cells resulted in prostate glands containing abnormalities in cell morphology and gland architecture. A population of castration-resistant Hes1-expressing cells was revealed in the adult prostate, with the ability to repopulate prostate epithelium following androgen supplementation. Deletion of AR in Hes1-expressing cells diminishes their regenerative ability. These lines of evidence demonstrate a critical role for the AR in Notch-responsive cells during the course of prostate development, morphogenesis, and regeneration, and implicate a mechanism underlying interaction between the androgen and Notch signaling pathways in the mouse prostate.

Analysis of hedgehog signaling in periocular sebaceous carcinoma

PURPOSE

Sebaceous carcinoma (SC) is a clinical masquerader of benign conditions resulting in significant eye morbidity, sometimes leading to extensive surgical treatment including exenteration, and even mortality. Little is known about the genetic or molecular basis of SC. This study identifies the involvement of Hedgehog (Hh) signaling in periocular SC.

METHODS

Fifteen patients with periocular SC patients were compared to 15 patients with eyelid nodular basal cell carcinoma (nBCC; a known Hh tumor), alongside four normal individuals as a control for physiological Hh expression. Expression of Patched 1 (PTCH1), Smoothened (SMO), and glioma-associated zinc transcription factors (Gli1 and Gli2) were assessed in histological sections using immunohistochemistry and immunofluorescence (IF) techniques. Antibody specificity was verified using Western-blot analysis of a Gli1 over-expressed cancer cell line, LNCaP-Gli1. Semi-quantification compared tumors and control tissue using IF analysis by ImageJ software.

RESULTS

Expression of the Hh pathway was observed in SC for all four major components of the pathway. PTCH1, SMO, and Gli2 were more significantly upregulated in SC (P < 0.01) compared to nBCC. Stromal expression of PTCH1 and Gli2 was observed in SC (P < 0.01). In contrast, stromal expression of these proteins in nBCC was similar or down-regulated compared to physiological Hh controls.

CONCLUSIONS

The Hh signaling pathway is significantly more upregulated in periocular SC compared to nBCC, a known aberrant Hh pathway tumor. Furthermore, the stroma of the SC demonstrated Hh upregulation, in particular Gli2, compared to nBCC. Targeting of this pathway may be a potential treatment strategy for SC.

Morphoregulatory pathways in prostate ductal development

The mouse prostate is a male sex-accessory gland comprised of a branched ductal network arranged into three separate bilateral lobes: the anterior, dorsolateral, and ventral lobes. Prostate ductal development is the primary morphogenetic event in prostate development and requires a complex regulation of spatiotemporal factors. This review provides an overview of prostate development and the major genetic regulators and signaling pathways involved. To identify new areas for further study, we briefly highlight the likely important, but relatively understudied, role of the extracellular matrix (ECM). Finally, we point out the potential importance of the ECM in influencing the behavior and prognosis of prostate cancer. Developmental Dynamics 246:89-99, 2017. © 2016 Wiley Periodicals, Inc.

Inhibition of Gli1-mediated prostate cancer cell proliferation by inhibiting the mTOR/S6K1 signaling pathway

Ectopic activation of the canonical Hedgehog signaling pathway is involved in the development and progression of prostate cancer, which is one of the leading causes of cancer-associated mortality in males worldwide. However, the role of the non-canonical Hedgehog signaling pathway in prostate cancer remains generally unexplored. In the present study, it was identified that Gli (glioma-associated oncogene)1 and Gli2 were highly expressed at the protein level in the androgen-independent prostate cancer cell lines PC3 and DU145, but not in the androgen-dependent cancer cell line LNCaP. Silencing of Gli1 using small interfering RNA markedly decreased PC3 cell viability and liquid colony formation in vitro. The Gli1/2-specific inhibitor GANT61 markedly decreased cell viability by inducing cell apoptosis in PC3 and DU145 cells. GANT61 also alleviated liquid colony formation efficiency in PC3 and DU145 cells, suggesting that the activity of Gli1 is required for prostate cancer cell survival. To explore further the upstream signaling pathway involved in the regulation of Gli1 expression, it was identified that tumor necrosis factor α-triggered mammalian target of rapamycin (mTOR)/p70 ribosomal protein S6 kinase 1 (S6K1) activation was required for Gli1 expression. Pharmacological and genetic inhibition of S6K1 activation markedly decreased Gli1 and its downstream target gene mRNA expression. In addition, the phosphoinositide 3-kinase/mTOR inhibitor BEZ235 markedly decreased in vitro PC3 cell proliferation. The results of the present study indicate that the non-canonical Hedgehog pathway (mTOR/S6K1/Gli1) contributes to the development and progression of prostate cancer and that Gli1 is a potential therapeutic target in the treatment of prostate cancer.

Prostate organogenesis: tissue induction, hormonal regulation and cell type specification

Prostate organogenesis is a complex process that is primarily mediated by the presence of androgens and subsequent mesenchyme-epithelial interactions. The investigation of prostate development is partly driven by its potential relevance to prostate cancer, in particular the apparent re-awakening of key developmental programs that occur during tumorigenesis. However, our current knowledge of the mechanisms that drive prostate organogenesis is far from complete. Here, we provide a comprehensive overview of prostate development, focusing on recent findings regarding sexual dimorphism, bud induction, branching morphogenesis and cellular differentiation.

RET-mediated glial cell line-derived neurotrophic factor signaling inhibits mouse prostate development

In humans and rodents, the prostate gland develops from the embryonic urogenital sinus (UGS). The androgen receptor (AR) is thought to control the expression of morphogenetic genes in inductive UGS mesenchyme, which promotes proliferation and cytodifferentiation of the prostatic epithelium. However, the nature of the AR-regulated morphogenetic genes and the mechanisms whereby AR controls prostate development are not understood. Glial cell line-derived neurotrophic factor (GDNF) binds GDNF family receptor α1 (GFRα1) and signals through activation of RET tyrosine kinase. Gene disruption studies in mice have revealed essential roles for GDNF signaling in development; however, its role in prostate development is unexplored. Here, we establish novel roles of GDNF signaling in mouse prostate development. Using an organ culture system for prostate development and Ret mutant mice, we demonstrate that RET-mediated GDNF signaling in UGS increases proliferation of mesenchyme cells and suppresses androgen-induced proliferation and differentiation of prostate epithelial cells, inhibiting prostate development. We also identify Ar as a GDNF-repressed gene and Gdnf and Gfrα1 as androgen-repressed genes in UGS, thus establishing reciprocal regulatory crosstalk between AR and GDNF signaling in prostate development.

MAOA-Dependent Activation of Shh-IL6-RANKL Signaling Network Promotes Prostate Cancer Metastasis by Engaging Tumor-Stromal Cell Interactions

Metastasis is a predominant cause of death for prostate cancer (PCa) patients; however, the underlying mechanisms are poorly understood. We report that monoamine oxidase A (MAOA) is a clinically and functionally important mediator of PCa bone and visceral metastases, activating paracrine Shh signaling in tumor-stromal interactions. MAOA provides tumor cell growth advantages in the bone microenvironment by stimulating interleukin-6 (IL6) release from osteoblasts, and triggers skeletal colonization by activating osteoclastogenesis through osteoblast production of RANKL and IL6. MAOA inhibitor treatment effectively reduces metastasis and prolongs mouse survival by disengaging the Shh-IL6-RANKL signaling network in stromal cells in the tumor microenvironment. These findings provide a rationale for targeting MAOA and its associated molecules to treat PCa metastasis.

Paracrine sonic hedgehog signaling contributes significantly to acquired steroidogenesis in the prostate tumor microenvironment

Despite the substantial benefit of androgen deprivation therapy (ADT) for metastatic prostate cancer, patients often progress to castration-resistant disease (CRPC) that is more difficult to treat. CRPC is associated with renewed androgen receptor activity in tumor cells and restoration of tumor androgen levels through acquired intratumoral steroidogenesis (AIS). Although prostate cancer (PCa) cells have been shown to have steroidogenic capability in vitro, we previously found that benign prostate stromal cells (PrSCs) can also synthesize testosterone (T) from an adrenal precursor, DHEA, when stimulated with a hedgehog (Hh) pathway agonist, SAG. Here, we show exposure of PrSCs to a different Smoothened (Smo) agonist, Ag1.5, or to conditioned medium from sonic hedgehog overexpressing LNCaP cells induces steroidogenic enzyme expression in PrSCs and significantly increases production of T and its precursor steroids in a Smo-dependent manner from 22-OH-cholesterol substrate. Hh agonist-/ligand-treated PrSCs produced androgens at a rate similar to or greater than that of PCa cell lines. Likewise, primary bone marrow stromal cells became more steroidogenic and produced T under the influence of Smo agonist. Treatment of mice bearing LNCaP xenografts with a Smo antagonist, TAK-441, delayed the onset of CRPC after castration and substantially reduced androgen levels in residual tumors. These outcomes support the idea that stromal cells in ADT-treated primary or metastatic prostate tumors can contribute to AIS as a consequence of a paracrine Hh signaling microenvironment. As such, Smo antagonists may be useful for targeting prostate tumor stromal cell-derived AIS and delaying the onset of CRPC after ADT.

Primary cilia: a link between hormone signalling and endocrine-related cancers?

Primary cilia are sensory organelles that play a role as signalling hubs. Disruption of primary cilia structure and function is increasingly recognised in a range of cancers, with a growing body of evidence suggesting that ciliary disruption contributes to tumourigenesis. This review considers the role of primary cilia in the pathogenesis of endocrine-related cancers.

Hedgehog Signaling in Prostate Development, Regeneration and Cancer

The prostate is a developmental model system study of prostate growth regulation. Historically the research focus was on androgen regulation of development and growth and instructive interactions between the mesenchyme and epithelium. The study of Hh signaling in prostate development revealed important roles in ductal morphogenesis and in epithelial growth regulation that appear to be recapitulated in prostate cancer. This overview of Hh signaling in the prostate will address the well-described role of paracrine signaling prostate development as well as new evidence suggesting a role for autocrine signaling, the role of Hh signaling in prostate regeneration and reiterative activities in prostate cancer.

Tbx18 Regulates the Differentiation of Periductal Smooth Muscle Stroma and the Maintenance of Epithelial Integrity in the Prostate

The T-box transcription factor TBX18 is essential to mesenchymal cell differentiation in several tissues and Tbx18 loss-of-function results in dramatic organ malformations and perinatal lethality. Here we demonstrate for the first time that Tbx18 is required for the normal development of periductal smooth muscle stromal cells in prostate, particularly in the anterior lobe, with a clear impact on prostate health in adult mice. Prostate abnormalities are only subtly apparent in Tbx18 mutants at birth; to examine postnatal prostate development we utilized a relatively long-lived hypomorphic mutant and a novel conditional Tbx18 allele. Similar to the ureter, cells that fail to express Tbx18 do not condense normally into smooth muscle cells of the periductal prostatic stroma. However, in contrast to ureter, the periductal stromal cells in mutant prostate assume a hypertrophic, myofibroblastic state and the adjacent epithelium becomes grossly disorganized. To identify molecular events preceding the onset of this pathology, we compared gene expression in the urogenital sinus (UGS), from which the prostate develops, in Tbx18-null and wild type littermates at two embryonic stages. Genes that regulate cell proliferation, smooth muscle differentiation, prostate epithelium development, and inflammatory response were significantly dysregulated in the mutant urogenital sinus around the time that Tbx18 is first expressed in the wild type UGS, suggesting a direct role in regulating those genes. Together, these results argue that Tbx18 is essential to the differentiation and maintenance of the prostate periurethral mesenchyme and that it indirectly regulates epithelial differentiation through control of stromal-epithelial signaling.

Ornithine Decarboxylase Activity Is Required for Prostatic Budding in the Developing Mouse Prostate

The prostate is a male accessory sex gland that produces secretions in seminal fluid to facilitate fertilization. Prostate secretory function is dependent on androgens, although the mechanism by which androgens exert their effects is still unclear. Polyamines are small cationic molecules that play pivotal roles in DNA transcription, translation and gene regulation. The rate-limiting enzyme in polyamine biosynthesis is ornithine decarboxylase, which is encoded by the gene Odc1. Ornithine decarboxylase mRNA decreases in the prostate upon castration and increases upon administration of androgens. Furthermore, testosterone administered to castrated male mice restores prostate secretory activity, whereas administering testosterone and the ornithine decarboxylase inhibitor D,L-α-difluromethylornithine (DFMO) to castrated males does not restore prostate secretory activity, suggesting that polyamines are required for androgens to exert their effects. To date, no one has examined polyamines in prostate development, which is also androgen dependent. In this study, we showed that ornithine decarboxylase protein was expressed in the epithelium of the ventral, dorsolateral and anterior lobes of the adult mouse prostate. Ornithine decarboxylase protein was also expressed in the urogenital sinus (UGS) epithelium of the male and female embryo prior to prostate development, and expression continued in prostatic epithelial buds as they emerged from the UGS. Inhibiting ornithine decarboxylase using DFMO in UGS organ culture blocked the induction of prostatic buds by androgens, and significantly decreased expression of key prostate transcription factor, Nkx3.1, by androgens. DFMO also significantly decreased the expression of developmental regulatory gene Notch1. Other genes implicated in prostatic development including Sox9, Wif1 and Srd5a2 were unaffected by DFMO. Together these results indicate that Odc1 and polyamines are required for androgens to exert their effect in mediating prostatic bud induction, and are required for the expression of a subset of prostatic developmental regulatory genes including Notch1 and Nkx3.1.

Notch signaling in the prostate: critical roles during development and in the hallmarks of prostate cancer biology

PURPOSE

This review aims to summarize the evidence that Notch signaling is associated with prostate development, tumorigenesis and prostate tumor progression.

METHODS

Studies in PubMed database were searched using the keywords of Notch signaling, prostate development and prostate cancer. Relevant literatures were identified and summarized.

RESULTS

The Notch pathway plays an important role in determining cell fate, proliferation, differentiation and apoptosis. Recent findings have highlighted the involvement of Notch signaling in prostate development and in the maintenance of adult prostate homeostasis. Aberrant Notch expression in tissues leads to dysregulation of Notch functions and promotes various neoplasms, including prostate cancer. High expression of Notch has been implicated in prostate cancer, and its expression increases with higher cancer grade. However, the precise role of Notch in prostate cancer has yet to be clearly defined. The roles of Notch either as an oncogene or tumor suppressor in prostate cancer hallmarks such as cell proliferation, apoptosis and anoikis, hypoxia, migration and invasion, angiogenesis as well as the correlation with metastasis are therefore discussed.

CONCLUSIONS

Notch signaling is a complicated signaling pathway in modulating prostate development and prostate cancer. Understanding and manipulating Notch signaling could therefore be of potential therapeutic value in combating prostate cancer.

Hedgehog signaling in prostate epithelial-mesenchymal growth regulation

The prostate gland plays an important role in male reproduction, and is also an organ prone to diseases such as benign prostatic hyperplasia (BPH) and prostate cancer. The prostate consists of ducts with an inner layer of epithelium surrounded by stroma. Reciprocal signaling between these two cell compartments is instrumental to normal prostatic development, homeostasis, regeneration, as well as tumor formation. Hedgehog (HH) signaling is a master regulator in numerous developmental processes. In many organs, HH plays a key role in epithelial-mesenchymal signaling that regulates organ growth and tissue differentiation, and abnormal HH signaling has been implicated in the progression of various epithelial carcinomas. In this review, we focus on recent studies exploring the multipotency of endogenous postnatal and adult epithelial and stromal stem cells and studies addressing the role of HH in prostate development and cancer. We discuss the implications of the results for a new understanding of prostate development and disease. Insight into the cellular and molecular mechanisms underlying epithelial-mesenchymal growth regulation should provide a basis for devising innovative therapies to combat diseases of the prostate.

Expression of the Shh/Bmp4 signaling pathway during the development of anorectal malformations in a male rat model of prenatal exposure to di(n-butyl) phthalate

Sonic hedgehog (Shh)/bone morphogenetic protein 4 (Bmp4) is an androgen-regulated signaling pathway that has been shown to be crucial for embryonic development.

Glial cell line-derived neurotrophic factor induces cell proliferation in the mouse urogenital sinus

Glial cell line-derived neurotrophic factor (GDNF) is a TGFβ family member, and GDNF signals through a glycosyl-phosphatidylinositol-linked cell surface receptor (GFRα1) and RET receptor tyrosine kinase. GDNF signaling plays crucial roles in urogenital processes, ranging from cell fate decisions in germline progenitors to ureteric bud outgrowth and renal branching morphogenesis. Gene ablation studies in mice have revealed essential roles for GDNF signaling in urogenital development, although its role in prostate development is unclear. We investigated the functional role of GDNF signaling in the urogenital sinus (UGS) and the developing prostate of mice. GDNF, GFRα1, and RET show time-specific and cell-specific expression during prostate development in vivo. In the UGS, GDNF and GFRα1 are expressed in the urethral mesenchyme (UrM) and epithelium (UrE), whereas RET is restricted to the UrM. In each lobe of the developing prostate, GDNF and GFRα1 expression declines in the epithelium and becomes restricted to the stroma. Using a well-established organ culture system, we determined that exogenous GDNF increases proliferation of UrM and UrE cells, altering UGS morphology. With regard to mechanism, GDNF signaling in the UrM increased RET expression and phosphorylation of ERK1/2. Furthermore, inhibition of RET kinase activity or ERK kinases suppressed GDNF-induced proliferation of UrM cells but not UrE cells. We therefore propose that GDNF signaling in the UGS increases proliferation of UrM and UrE cells by different mechanisms, which are distinguished by the role of RET receptor tyrosine kinase and ERK kinase signaling, thus implicating GDNF signaling in prostate development and growth.

Spatially restricted Hedgehog signalling regulates HGF-induced branching of the adult prostate

Branching morphogenesis is thought to be governed by epithelial-stromal interactions, but the mechanisms underlying specification of branch location remain largely unknown. Prompted by the striking absence of Hedgehog (Hh) response at the sites of nascent buds in regenerating tubules of the adult prostate, we investigated the role of Hh signaling in adult prostate branching morphogenesis. We find that pathway activity is localized to stromal cells, and that its attenuation by genetic or pharmacologic manipulation leads to increased branching. Decreased pathway activity correlates with increased stromal production of Hepatocyte growth factor (Hgf), and we show that Hgf induces epithelial tubule branching. Regulation of Hgf expression by Hh signaling is indirect, mediated by Hh-induced expression of microRNAs miR-26a and miR-26b, which in turn down-regulate expression of Hgf. Prostate tubule branching thus may be initiated from regions of low Hh pathway activity, with implications for the prostatic hyperplasia commonly observed in late adulthood.

Molecular pathways and targets in prostate cancer

Prostate cancer co-opts a unique set of cellular pathways in its initiation and progression. The heterogeneity of prostate cancers is evident at earlier stages, and has led to rigorous efforts to stratify the localized prostate cancers, so that progression to advanced stages could be predicted based upon salient features of the early disease. The deregulated androgen receptor signaling is undeniably most important in the progression of the majority of prostate tumors. It is perhaps because of the primacy of the androgen receptor governed transcriptional program in prostate epithelium cells that once this program is corrupted, the consequences of the ensuing changes in activity are pleotropic and could contribute to malignancy in multiple ways. Following localized surgical and radiation therapies, 20-40% of patients will relapse and progress, and will be treated with androgen deprivation therapies. The successful development of the new agents that inhibit androgen signaling has changed the progression free survival in hormone resistant disease, but this has not changed the almost ubiquitous development of truly resistant phenotypes in advanced prostate cancer. This review summarizes the current understanding of the molecular pathways involved in localized and metastatic prostate cancer, with an emphasis on the clinical implications of the new knowledge.

Phosphodiesterase 4D inhibitors limit prostate cancer growth potential

Phosphodiesterase 4D (PDE4D) has recently been implicated as a proliferation-promoting factor in prostate cancer and is overexpressed in human prostate carcinoma. However, the effects of PDE4D inhibition using pharmacologic inhibitors have not been examined in prostate cancer. These studies examined the effects of selective PDE4D inhibitors, NVP-ABE171 and cilomilast, as anti-prostate cancer therapies in both in vitro and in vivo models. The effects of PDE4D inhibitors on pathways that are critical in prostate cancer and/or downstream of cyclic AMP (cAMP) were examined. Both NVP-ABE171 and cilomilast decreased cell growth. In vitro, PDE4D inhibitors lead to decreased signaling of the sonic hedgehog (SHH), androgen receptor (AR), and MAPK pathways, but growth inhibition was best correlated to the SHH pathway. PDE4D inhibition also reduced proliferation of epithelial cells induced by paracrine signaling from cocultured stromal cells that had activated hedgehog signaling. In addition, PDE4D inhibitors decreased the weight of the prostate in wild-type mice. Prostate cancer xenografts grown in nude mice that were treated with cilomilast or NVP-ABE171 had decreased wet weight and increased apoptosis compared with vehicle-treated controls. These studies suggest the pharmacologic inhibition of PDE4D using small-molecule inhibitors is an effective option for prostate cancer therapy.

IMPLICATIONS

PDE4D inhibitors decrease the growth of prostate cancer cells in vivo and in vitro, and PDE4D inhibition has therapeutic potential in prostate cancer.

A dual role for SHH during phallus development in a marsupial

The mammalian phallus arises from identical primordia in both sexes and is patterned in part by the key morphogen Sonic hedgehog (SHH). We have investigated SHH and other morphogens during phallus development in the tammar wallaby. In this marsupial, testis differentiation and androgen production occurs just after birth, but it takes a further 50-60 days before the phallus becomes sexually dimorphic. One day before birth, SHH was expressed in both sexes in the urethral epithelium. In males, there was a marked upregulation of SHH, GLI2, and AR at day 50 postpartum, a time when testicular androgen production falls. SHH, GLI2, and AR were downregulated in female pouch young treated with androstanediol from days 24-50, but not when treatments were begun at day 29, suggesting an early window of androgen sensitivity. SHH, GLI2, and AR expression in the phallus of males castrated at day 23 did not differ from controls, but there was an increase in SHH and GLI2 and a decrease in FGF8 and BMP4 expression when the animals were castrated at day 29. These results suggest that the early patterning by SHH is androgen-independent followed by an androgen-dependent window of sensitivity and a sharp rise in SHH expression after androgen withdrawal at day 50.

Hedgehog signaling is active in human prostate cancer stroma and regulates proliferation and differentiation of adjacent epithelium

BACKGROUND

Contribution of stromal Hedgehog (Hh) signaling is evident in the prostate gland in mice, but needs translation to human tissues if Hh therapeutics are to be used effectively. Our goal was to determine if primary human prostate fibroblasts contain cilia, and respond to prostate Hh signaling.

METHODS

Primary human prostate cancer-associated (CAFs), and adjacent non-malignant (NPFs) fibroblasts isolated from human tissue specimens were analyzed using immunofluorescence, real-time PCR, and available array data. Cell culture and tissue recombination were used to determine responsiveness of human fibroblasts to Hh pathway manipulation and the paracrine effects of stromal Hh signaling, respectively.

RESULTS

Prostatic fibroblasts were capable of forming primary cilia, with the capacity for active Hh signaling as seen by Smo co-localization to the tip of the primary cilium. Expression of genes known to represent a signature of active Hh signaling in the prostate (especially Fgf5 and Igfbp6) were increased in CAFs compared to NPFs. The level of canonical Hh genes and prostate Hh signature genes were rarely synchronous; with lower doses of Purmorphamine/BMS-833923 regulating canonical transcription factors, and higher doses effecting prostate Hh signature genes. Grafts consisting of NPFs with constitutively active Hh signaling induced increased proliferation and dedifferentiation of adjacent non-malignant BPH-1 epithelial cells.

CONCLUSIONS

These data show that human prostatic fibroblasts have the capacity for Hh signaling and manipulation. Increased expression of a signature of prostatic Hh genes in the prostate tumor microenvironment suggests a role in the epithelial transformations driving prostate cancer (PCa).

Sonic hedgehog signals to multiple prostate stromal stem cells that replenish distinct stromal subtypes during regeneration

The adult mouse prostate has a seemingly endless capacity for regeneration, and sonic hedgehog (SHH) signaling has been implicated in this stem cell-driven process. However, it is not clear whether SHH acts on the epithelium or stromal cells that secrete factors required for epithelial expansion. Because little is known about stromal stem cells compared with their epithelial counterparts, we used in vivo mouse genetics tools to characterize four prostate stromal subtypes and their stem cells. Using knockin reporter alleles, we uncovered that SHH signals from prostate basal epithelial cells to adjacent stromal cells. Furthermore, the SHH target gene Gli1 is preferentially expressed in subepithelial fibroblast-like cells, one of four prostate stromal subtypes and the subtype closest to the epithelial source of SHH. Using Genetic Inducible Fate Mapping to mark adult Gli1- or Smooth muscle actin-expressing cells and follow their fate during regeneration, we uncovered that Gli1-expressing cells exhibit long-term self-renewal capacity during multiple rounds of androgen-mediated regeneration after castration-induced involution, and depleted smooth muscle cells are mainly replenished by preexisting smooth muscle cells. Based on our Genetic Inducible Fate Mapping studies, we propose a model where SHH signals to multiple stromal stem cells, which are largely unipotent in vivo.

Nitric Oxide Synthase is Necessary for Normal Urogenital Development

Introduction

Neuronal nitric oxide synthase (NOS-I) is significantly decreased with Cavernous Nerve (CN) injury in Erectile Dysfunction (ED) models. Increased apoptosis and collagen deposition accompany decreased NOS/CN injury, however these changes are typically attributed to the altered signaling of other factors, and a contribution of NOS in maintenance of urogenital structures has not previously been examined. Morphological changes in the corpora cavernosa occur at the same time as decreased NOS, suggesting a potential connection between decreased/inhibited NOS and morphological changes associated with ED. In this study we propose that NOS impacts urogenital morphology during development and will examine this hypothesis by NOS inhibition with L-NAME.

Methods

Primary outcomes were H&E, western and TUNEL to determine if penis, prostate and bladder morphology were altered with L-NAME treatment of Postnatal day 4 (P4) Sprague Dawley rats for 8 days. Tissue weight and immunohistochemical analysis for NOS were performed. Secondary evaluation of NOS-I regulation by Sonic Hedgehog (SHH) was examined by SHH inhibition in the pelvic ganglia (PG) and NOS-I protein was quantified by western in the PG/CN and penis. Nos abundance was quantified by RT-PCR during urogenital development and after CN injury.

Results

Apoptosis increased and penis, prostate and bladder morphology were altered with L-NAME. NOS inhibition decreased bladder weight 25%. SHH inhibition decreased NOS-I 35% in the PG/CN and 47% in the penis. Nos-III expression spiked within the first two weeks after birth in the penis but remained abundant in the adult. In the prostate, Nos-III was abundant immediately after birth and declined steadily with age. Nos-I expression in the PG/CN decreased sharply with CN injury and returned to baseline by 7 days.

Conclusions

NOS is required for normal urogenital development. Since NOS is decreased with ED, it may contribute to the abnormal morphology observed in ED patients and animal models.

Nerve growth factor signaling following unilateral pelvic ganglionectomy in the rat ventral prostate is age dependent

Benign prostatic hyperplasia (BPH) is a serious health concern and is an underlying cause of lower urinary tract symptoms (LUTS) in many men. In affected men, LUTS/BPH is believed to result from benign proliferation of the prostate resulting in bladder outlet obstruction. Postnatal growth of the prostate is controlled via growth factor and endocrine mechanisms. However, little attention had been given to the function of the autonomic nervous system in prostate growth and differentiation. Nerve growth factor (NGF) is a prostatic mitogen that has a trophic role in autonomic sensory end organ interaction. In this study, we examine how the autonomic nervous system influences prostate growth as a function of age by quantifying NGF in the rat ventral prostate (VP) after pelvic ganglionectomy. Unilateral pelvic ganglionectomy was performed on postnatal days 30 (P30), 60 and 120 Sprague-Dawley rats in comparison to sham controls (n=39). Semiquantitative RT-PCR, Western blotting and immunohistochemical analysis for NGF were performed on denervated, intact (contralateral side) and sham control VP 7 days after surgery. Ngf RNA expression was significantly increased in the denervated and intact hyperplastic VP. Western blotting showed age-dependent increases in NGF protein at P60 in the contralateral intact VP. NGF was localized in the nerves, basal cells and columnar epithelium of the prostatic ducts. Denervation causes age-dependent increases in NGF in the VP, which is a potential mechanism by which the autonomic nervous system may regulate prostate growth and lead to BPH/LUTS.

Hedgehog signaling in prostate cancer and its therapeutic implication

Activation of Hedgehog (Hh) signaling is implicated in the development and progression of several tumor types, including prostate cancer, which is still the most common non-skin malignancy and the third leading cause of cancer-related mortality in men in industrialized countries worldwide. Several studies have indicated that the Hh pathway plays a crucial role in the development as well as in the progression of this disease to more aggressive and even therapy-resistant disease states. Moreover, preclinical data have shown that inhibition of Hh signaling has the potential to reduce prostate cancer invasiveness and metastatic potential. Clinical trials investigating the benefit of Hh inhibitors in patients with prostate cancer have recently been initiated. However, acquired drug resistance has already been observed in other tumor types after long-term Hh inhibition. Therefore, combining Hh inhibitors with ionizing radiation, chemotherapy or other molecular targeted agents could represent an alternative therapeutic strategy. In this review, we will highlight the role of Hh signaling in the development and progression of prostate cancer and summarize the different therapeutic applications of Hedgehog inhibition.

Role of GLI-1 in epidermal growth factor-induced invasiveness of ARCaPE prostate cancer cells

Epidermal growth factor (EGF) signaling and Hedgehog (HH) signaling are both involved in prostate cancer (PCa) progression, yet the mechanisms through which these two pathways are synergistically linked require elucidation. In the present study, we aimed to ascertain how EGF and the HH signaling transcription factor GLI-1 are linked in prostate cancer invasiveness. ARCaP human prostate cancer cells, which included ARCaPE and ARCaPM cells, were used as a model in the present study. The expression of EGF receptor (EGFR) and the HH signaling transcriptional factor GLI-1 were detected in ARCaPE cells by immunofluorescence, and the ARCaPE cells were treated with human recombinant EGF protein (hrEGF) for 4 consecutive days in vitro. Transwell invasion assays were performed in the ARCaPE cells following treatment with DMSO (vehicle control), hrEGF, GATN61 (GLI-1-specific inhibitor), hrEGF plus GANT61 and in the ARCaPM cells. The expression of phosphorylated extracellular signal regulated kinase (p-ERK), total ERK and GLI-1 was detected by western blotting in ARCaPE cells at different time-points following treatment with hrEGF. The expression of EGFR and GLI-1 was detected in ARCaPE cells, which exhibited a cobblestone-like morphology, while after treatment with hrEGF, the cell morphology was altered to a spindle-shaped mesenchymal cell morphology. Transwell invasion assays demonstrated that hrEGF dramatically enhanced the invasive capability of the ARCaPE cells (p<0.05). Additionally, western blot assay demonstrated that the expression levels of p-ERK and GLI-1 in ARCaPE cells increased in a time-dependent manner after treatment with hrEGF (p<0.05); however, the expression levels of total ERK in the cells remained relatively unchanged. It also demonstrated that the GLI-1 inhibitor GANT61 could reverse the enhanced invasive effect induced by EGF in ARCaPE cells (p<0.05). Our preliminary in vitro study showed that EGF signaling may increase the invasive capability of ARCaPE human prostate cancer cells via upregulation of p-ERK and the HH signaling transcriptional factor GLI-1. Additionally, this enhanced cell invasive effect was reversed by a GLI-1-specific inhibitor in vitro. Consequently, it indicates that both EGF and HH signaling are synergistically involved in the progression of human prostate cancer ARCaP cells, and GlI-1 may be one of the important effectors, which is activated by EGF downstream signaling, to promote the invasiveness of ARCaPE prostate cancer cells.

Differential stage-dependent regulation of prostatic epithelial morphogenesis by Hedgehog signaling

Published studies of Hh (Hedgehog) signaling in the developing prostate have reported varying and discrepant effects on epithelial proliferation, ductal morphogenesis and growth. We report here that these differing observations accrue from stage-specific effects of Hh signaling in the developing prostate. Using in vitro organ cultures of the E16 UGS and P1 prostate, we show that ectopic Hh pathway activation stimulates epithelial proliferation prenatally, but inhibits epithelial proliferation postnatally. Extrapolating from previously published observations that Hh target gene expression is altered in the reactive stroma of prostate cancer, we examined and found discordant regulation of a subset of target genes by Hh signaling in the prenatal and postnatal prostate. Cell based studies and recombination assays show that these changes are not simply attributable to the age of the mesenchyme or the epithelium, but more likely reflect a complex regulation by the cellular microenvironment. To determine the in vivo relevance of these observations, we examined the effect of transgenic activation of Hh signaling on epithelial proliferation in the prenatal and postnatal prostate and confirmed the operation of stage-specific effects. These observations demonstrate stage-specific differences in the effect of Hh signaling on epithelial proliferation in the developing prostate and suggest that these are a product of complex interactions determined by the cellular microenvironment.

TAK-441, a novel investigational smoothened antagonist, delays castration-resistant progression in prostate cancer by disrupting paracrine hedgehog signaling

Hedgehog (Hh) signaling is a highly conserved intercellular and intracellular communication mechanism that governs organogenesis and is dysregulated in cancers of numerous tissues, including prostate. Up-regulated expression of the Hh ligands, Sonic (Shh) and Desert (Dhh), has been reported in androgen-deprived and castration-resistant prostate cancer (CRPC). In a cohort of therapy naive, short- and long-term neoadjuvant hormone therapy-treated (NHT), and CRPC specimens, we observed elevated Dhh expression predominantly in long-term NHT specimens and elevated Shh expression predominantly in CRPC specimens. Together with previously demonstrated reciprocal signaling between Shh-producing prostate cancer (PCa) cells and urogenital mesenchymal fibroblasts, these results suggest that castration-induced Hh expression promotes CRPC progression through reciprocal paracrine signaling within the tumor microenvironment. We tested whether the orally available Smoothened (Smo) antagonist, TAK-441, could impair castration-resistant progression of LNCaP PCa xenografts by disrupting paracrine Hh signaling. Although TAK-441 or cyclopamine did not affect androgen withdrawal-induced Shh up-regulation or viability of LNCaP cells, castration-resistant progression of LNCaP xenografts was significantly delayed in animals treated with TAK-441. In TAK-441-treated xenografts, expression of murine orthologs of the Hh-activated genes, Gli1, Gli2 and Ptch1, was substantially suppressed, while expression of the corresponding human orthologs was unaffected. As androgen-deprived LNCaP cells up-regulate Shh expression, but are not sensitive to Smo antagonists, these studies indicate that TAK-441 leads to delayed castration-resistant progression of LNCaP xenografts by disrupting paracrine Hh signaling with the tumor stroma. Thus, paracrine Hh signaling may offer unique opportunities for prognostic biomarker development, drug targeting and therapeutic response monitoring of PCa progression.

Recent advances in prostate development and links to prostatic diseases

The prostate is a branched ductal-acinar gland that is part of the male reproductive tract. Prostate development depends upon the integration of steroid hormone signals, paracrine interactions between the stromal and epithelial tissue layers, and the actions of cell autonomous factors. Several genes and signaling pathways are known to be required for one or more steps of prostate development including epithelial budding, duct elongation, branching morphogenesis, and/or cellular differentiation. Recent progress in the field of prostate development has included the application of genome-wide technologies including serial analysis of gene expression, expression profiling microarrays, and other large-scale approaches to identify new genes and pathways that are essential for prostate development. The aggregation of experimental results into online databases by organized multilab projects including the Genitourinary Developmental Molecular Atlas Project has also accelerated the understanding of molecular pathways that function during prostate development and identified links between prostate anatomy and molecular signaling. Rapid progress has also recently been made in understanding the nature and role of candidate stem cells in the developing and adult prostate. This has included the identification of putative prostate stem cell markers, lineage tracing, and organ reconstitution studies. However, several issues regarding their origin, precise nature, and possible role(s) in disease remain unresolved. Nevertheless, several links between prostatic developmental mechanisms and the pathogenesis of prostatic diseases including benign prostatic hyperplasia and prostate cancer have led to recent progress on targeting developmental pathways as therapeutic strategies for these diseases.

Sox9 is required for prostate development and prostate cancer initiation

Prostate cancer is one of the most common malignancies and the second leading cause of death from cancer in men. The molecular mechanisms driving prostate carcinogenesis are complex; with several lines of evidence suggesting that the re-expression of conserved developmental programs plays a key role. In this study, we used conditional gene targeting and organ grafting, to describe conserved roles for the transcription factor Sox9 in the initiation of both prostate organogenesis and prostate carcinogenesis in murine models. Abrogation of Sox9 expression prior to the initiation of androgen signaling blocks the initiation of prostate development. Similarly, Sox9 deletion in two genetic models of prostate cancer (TRAMP and Hi-Myc) prevented cancer initiation. Expression profiling of Sox9-null prostate epithelial cells revealed that the role of Sox9 in the initiation of prostate development may relate to its regulation of multiple cytokeratins and cell adherence/polarity. Due to its essential role in cancer initiation, manipulation of Sox9 targets in at-risk men may prove useful in the chemoprevention of prostate cancer.

Hedgehog signaling plays roles in epithelial cell proliferation in neonatal mouse uterus and vagina

Both the uterus and vagina develop from the Müllerian duct but are quite distinct in morphology and function. To investigate factors controlling epithelial differentiation and cell proliferation in neonatal uterus and vagina, we focused on Hedgehog (HH) signaling. In neonatal mice, Sonic hh (Shh) was localized in the vaginal epithelium and Indian hh (Ihh) was slightly expressed in the uterus and vagina, whereas all Glioma-associated oncogene homolog (Gli) genes were mainly expressed in the stroma. The expression of target genes of HH signaling was high in the neonatal vagina and in the uterus, it increased with growth. Thus, in neonatal mice, Shh in the vaginal epithelium and Ihh in the uterus and vagina activated HH signaling in the stroma. Tissue recombinants showed that vaginal Shh expression was inhibited by the vaginal stroma and uterine Ihh expression was stimulated by the uterine stroma. Addition of a HH signaling inhibitor decreased epithelial cell proliferation in organ-cultured uterus and vagina and increased stromal cell proliferation in organ-cultured uterus. However, it did not affect epithelial differentiation or the expression of growth factors in organ-cultured uterus and vagina. Thus, activated HH signaling stimulates epithelial cell proliferation in neonatal uterus and vagina but inhibits stromal cell proliferation in neonatal uterus.

The role of Pax2 in mouse prostate development

BACKGROUND

Loss-of-function of Pax2 results in severe defects of the male reproductive system, and Pax2 expression is detected in mouse prostate lobes and human prostatic cancers. However, the role for Pax2 in prostate development remains poorly understood.

METHODS

The expression of Pax2 was examined by in situ hybridization at various developmental stages. Urogenital sinuses were dissected out at E18.5 from mouse Pax2 mutants and controls, cultured in vitro or grafted under the renal capsule of CD1 nude mice. The expression of prostate developmental regulatory factors was analyzed by semi-quantitative real-time PCR or immuohistochemistry.

RESULTS

Pax2 is expressed in the epithelial cells of prostate buds. Loss-of-function of Pax2 does not affect the initiation of prostatic buds, but in vitro culture assays show that the prostates of Pax2 mutants are hypomorphic and branching is severely disrupted compared to controls. RT-PCR data from Pax2 mutant prostates demonstrate increased expression levels of dorsolateral prostate marker MSMB and ventral prostate marker SBP and dramatically reduced expression levels of anterior prostate marker TGM4.

CONCLUSIONS

Pax2 is essential for mouse prostate development and regulates prostatic ductal growth, branching, and lobe-specific identity. These findings are important for understanding the molecular regulatory mechanisms in prostate development.

Atlas of Wnt and R-spondin gene expression in the developing male mouse lower urogenital tract

Prostate development is influenced by β-catenin signaling, but it is unclear which β-catenin activators are involved, where they are synthesized, and whether their mRNA abundance is influenced by androgens. We identified WNT/β-catenin-responsive β-galactosidase activity in the lower urogenital tract (LUT) of transgenic reporter mice, but β-galactosidase activity differed among the four mouse strains we examined. We used in situ hybridization to compare patterns of Wnts, r-spondins (Rspos, co-activators of β-catenin signaling), β-catenin-responsive mRNAs, and an androgen receptor-responsive mRNA in wild type fetal male, fetal female, and neonatal male LUT. Most Wnt and Rspo mRNAs were present in LUT during prostate development. Sexually dimorphic expression patterns were observed for WNT/β-catenin-responsive genes, and for Wnt2b, Wnt4, Wnt7a, Wnt9b, Wnt10b, Wnt11, Wnt16, and Rspo3 mRNAs. These results reveal sexual differences in WNT/β-catenin signaling in fetal LUT, supporting the idea that this pathway may be directly or indirectly responsive to androgens during prostate ductal development.

Targeted expression of GLI1 in the salivary glands results in an altered differentiation program and hyperplasia

Hedgehog (Hh) signaling is a regulator of salivary gland morphogenesis, but its role in postnatal glands has only recently begun to be addressed. To examine the effects of deregulated Hh signaling in the salivary gland, we expressed the Hh effector protein GLI1, in salivary epithelial cells using both cytokeratin 5 and mouse mammary tumor virus (MMTV) transgenic systems. Ectopic pathway activation resulted in restrained acinar differentiation, formation of cystic lesions, and prominent appearance of ductal structures. Moreover, induced expression of GLI1 aids the formation of hyperplastic lesions, which closely resemble GLI1-induced changes in murine skin and mammary glands, suggesting that GLI1 targets cells with similar characteristics in different tissues. Furthermore, GLI1-expressing salivary epithelial cells are actively dividing, and GLI1-induced lesions are proliferative, an incident accompanied by enhanced expression of the Hh target genes, cyclin D1, and Snail. GLI1-induced salivary lesions regress after transgene withdrawal and become histologically normalized. Taken together, our data reveal the ability of GLI1 to modulate salivary acinar differentiation and to promote proliferation of ductal epithelial cells.

Cholesterol and benign prostate disease

The origins of benign prostatic diseases, such as benign prostatic hyperplasia (BPH) and chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), are poorly understood. Patients suffering from benign prostatic symptoms report a substantially reduced quality of life, and the relationship between benign prostate conditions and prostate cancer is uncertain. Epidemiologic data for BPH and CP/CPPS are limited, however an apparent association between BPH symptoms and cardiovascular disease (CVD) has been consistently reported. The prostate synthesizes and stores large amounts of cholesterol and prostate tissues may be particularly sensitive to perturbations in cholesterol metabolism. Hypercholesterolemia, a major risk factor for CVD, is also a risk factor for BPH. Animal model and clinical trial findings suggest that agents that inhibit cholesterol absorption from the intestine, such as the class of compounds known as polyene macrolides, can reduce prostate gland size and improve lower urinary tract symptoms (LUTS). Observational studies indicate that cholesterol-lowering drugs reduce the risk of aggressive prostate cancer, while prostate cancer cell growth and survival pathways depend in part on cholesterol-sensitive biochemical mechanisms. Here we review the evidence that cholesterol metabolism plays a role in the incidence of benign prostate disease and we highlight possible therapeutic approaches based on this concept.

The role of sonic hedgehog-Gli2 pathway in the masculinization of external genitalia

During embryogenesis, sexually dimorphic organogenesis is achieved by hormones produced in the gonad. The external genitalia develop from a single primordium, the genital tubercle, and their masculinization processes depend on the androgen signaling. In addition to such hormonal signaling, the involvement of nongonadal and locally produced masculinization factors has been unclear. To elucidate the mechanisms of the sexually dimorphic development of the external genitalia, series of conditional mutant mouse analyses were performed using several mutant alleles, particularly focusing on the role of hedgehog signaling pathway in this manuscript. We demonstrate that hedgehog pathway is indispensable for the establishment of male external genitalia characteristics. Sonic hedgehog is expressed in the urethral plate epithelium, and its signal is mediated through glioblastoma 2 (Gli2) in the mesenchyme. The expression level of the sexually dimorphic genes is decreased in the glioblastoma 2 mutant embryos, suggesting that hedgehog signal is likely to facilitate the masculinization processes by affecting the androgen responsiveness. In addition, a conditional mutation of Sonic hedgehog at the sexual differentiation stage leads to abnormal male external genitalia development. The current study identified hedgehog signaling pathway as a key factor not only for initial development but also for sexually dimorphic development of the external genitalia in coordination with androgen signaling.

Hedgehog signaling protein expression and its association with prognostic parameters in prostate cancer: a retrospective study from the view point of new 2010 anatomic stage/prognostic groups

BACKGROUND

The expression of Hedgehog (Hh) signaling pathway in prostate cancer is well-known but its clinicopathologic role has not been elucidated well.

METHODS

Prostatectomy cases of prostate cancer (n=155) were prepared and assessed by clinicopathologic parameters including new 2010 anatomic stage/prognostic groups (ASPG) of prostate cancer. The expression of five Hh signaling proteins including Sonic hedgehog (Shh), Patched, Smoothened, and GLIoma-associated oncogene, in addition with Suppressor of fused (Su(fu)) were analyzed immunohistochemically. Real-time polymerase chain reaction was performed to assess the mRNA expression status.

RESULTS

The expression of each Hh signaling protein was significantly correlated with poor prognostic parameters such as larger tumor size, high pretreatment prostate-specific antigen (PSA), high Gleason score, perineural invasion and new ASPG. Among Hh signaling proteins, Sonic hedgehog and Smoothened expressions tend to have a significantly higher risk of PSA recurrence (P<0.001 and P=0.011, respectively). Multivariate analysis proved Shh expression as independent prognostic factors of PSA recurrence along with Gleason score, ASPG, tumor volume, and pretreatment PSA.

CONCLUSIONS

Hh signaling activity is significantly associated with worse prognostic parameters. Shh can be regarded as a poor prognostic factor for PSA recurrence.