Hormonal, cellular, and molecular regulation of normal and neoplastic prostatic development

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.

Corticosterone influences gerbil (Meriones unguiculatus) prostatic morphophysiology and alters its proliferation and apoptosis rates

Glucocorticoids (GCs) are hormones that are widely used in medicine; but although side effects are generally recognised, little is known about the precise mechanisms that is implicated in many of these side effects. Furthermore, GCs are highly correlated with stress and behaviour disorders. This study evaluated the effects of the glucocorticoid corticosterone on the ventral prostate of the Mongolian gerbil. Male gerbils (Meriones unguiculatus) (n = 5) received intraperitoneal injections of saline or corticosterone in doses of 0.5 mg/kg/day and 1.5 mg/kg/day for 5 days; while some of the animals were killed immediately after the treatment, the others were killed 5 days after the treatment period. The data show that corticosterone influences the structure and functionality of this organ. This hormone has anti-proliferative and anti-apoptotic properties in the prostate. In addition, the frequencies of the androgen (AR), oestrogen (ERα, ERβ) and glucocorticoid (GR) receptors changed. The frequencies of AR, GR and ERβ decreased in the Ct1/5 group; in the groups with rest period, the frequencies of GR increased and ERβ decreased in the epithelium. Changes in the proliferative index, apoptotic index and receptor activity may have contributed to the emergence of prostatic morphological alterations, such as the presence of cellular debris and inflammatory cells. Different doses of corticosterone had variable effects on the prostate, with a higher dose showing subtler effects and a lower dose showing more striking effects. The corticosterone effects on nuclear receptors were reverted or attenuated after a rest period, which was not observed for proliferation and apoptosis. In summary, we have demonstrated that corticosterone might influence the prostatic morphophysiology and that these changes may be linked in some way to the altered receptor distribution.

Dual effects of constitutively active androgen receptor and full-length androgen receptor for N-cadherin regulation in prostate cancer

Constitutively active androgen receptor (AR) variants have been involved in the expression of mesenchymal markers such as N-cadherin in prostate cancer (PCa). However, the underlying molecular mechanisms remain elusive. It remains unclear, whether N-cadherin gene (CDH2) is a direct transcriptional target of AR variants or whether the observed upregulation is due to indirect effects through additional regulatory factors. Moreover, the specific contribution of full-length AR and AR variants in N-cadherin regulation in PCa has never been explored deeply. To investigate this, we artificially mimicked the co-expression of AR variants together with a full-length AR and performed miRNA-seq, RNA-seq and ChIP assays. Our results were in favor of a direct AR variants action on CDH2. Our data also revealed a distinctive mode of action between full-length AR and AR variants to regulate N-cadherin expression. Both wild type AR and AR variants could interact with a regulatory element in intron 1 of CDH2. However, a higher histone H4 acetylation in this genomic region was only observed with AR variants. This suggests that full-length AR may play an occluding function to impede CDH2 upregulation. Our data further highlighted a negative effect of AR variants on the expression of the endogenous full-length AR in LNCaP. These differences in the mode of action of AR variants and full-length AR for the control of one key gene for prostate cancer progression could be worth considering for targeting AR variants in PCa.

The Y-located proto-oncogene TSPY exacerbates and its X-homologue TSPX inhibits transactivation functions of androgen receptor and its constitutively active variants

The gonadoblastoma gene, testis-specific protein Y-encoded (TSPY), on the Y chromosome and its X-homologue, TSPX, are cell cycle regulators and function as a proto-oncogene and a tumor suppressor respectively in human oncogenesis. TSPY and TSPX competitively bind to the androgen receptor (AR) and AR variants, such as AR-V7, at their conserved SET/NAP domain, and exacerbate and repress the transactivation of the AR/AR-V7 target genes in ligand dependent and independent manners respectively. The inhibitory domain has been mapped to the carboxyl acidic domain of TSPX, truncation of which renders TSPX to be stimulatory while its transposition to the C-terminus of TSPY results in an inhibitory hybrid protein. TSPY and TSPX co-localize with the endogenous AR, in the presence of ligand, on the promoters and differentially regulate the expression of the endogenous AR target genes in the androgen-responsive LNCaP prostate cancer cells. Transcriptome analysis shows that TSPY and TSPX expressions differentially affect significant numbers of canonical pathways, upstream regulators and cellular functions. Significantly, among the common ones, TSPY activates and TSPX inhibits numerous growth-related and oncogenic canonical pathways and cellular functions in the respective cell populations. Hence, TSPY and TSPX exert opposing effects on the transactivation functions of AR and AR-Vs important for various physiological and disease processes sensitive to male sex hormone actions, thereby not only affecting the pathogenesis of male-specific prostate cancer but also likely contributing to sex differences in the health and diseases of man.

Androgen receptor in cancer-associated fibroblasts influences stemness in cancer cells

Androgen receptor (AR) regulation pathways are essential for supporting the growth and survival of prostate cancer cells. Recently, sub-populations of prostate cancer cells have been identified with stem cell features and are associated with the emergence of treatment-resistant prostate cancer. Here, we explored the function of AR in prostate cancer-associated fibroblasts (CAFs) relative to growth and stem cell-associated characteristics. CAFs were isolated from the murine cPten^-/-L prostate cancer model and cultured with human prostate cancer epithelial (hPCa) cells. A murine-specific AR antisense oligonucleotide (ASO) was used to suppress the expression of AR in the CAF cells. CAFs express low, but significant levels of AR relative to fibroblasts derived from non-malignant tissue. CAFs promoted growth and colony formation of hPCa cells, which was attenuated by the suppression of AR expression. Surprisingly, AR-depleted CAFs promoted increased stem cell marker expression in hPCa cells. Interferon gamma (IFN-γ) and macrophage colony-stimulating factor (M-CSF) were increased in AR-depleted CAF cells and exhibited similar effects on stem cell marker expression as seen in the CAF co-culture systems. Clinically, elevated IFN-γ expression was found to correlate with histologic grade in primary prostate cancer samples. In summary, AR and androgen-dependent signaling are active in CAFs and exert significant effects on prostate cancer cells. IFN-γ and M-CSF are AR-regulated factors secreted by CAF cells, which promote the expression of stem cell markers in prostate cancer epithelial cells. Understanding how CAFs and other constituents of stromal tissue react to anti-cancer therapies may provide insight into the development and progression of prostate cancer.

Pubertal exposure to ethinylestradiol promotes different effects on the morphology of the prostate of the male and female gerbil during aging

In rodents, the final growth and maturation of the prostate occur at puberty, a crucial period for prostate development. The present study is a serological, morphological, morphometric, and immunohistochemical analysis of the effects of exposure to ethinylestradiol (EE) (15 µg/kg/day) during puberty (EE/PUB group) on the male ventral and female prostate in senile gerbils. In the study, male and female gerbils (Meriones unguiculatus) (42 days) received by gavage 15 μg/kg/day of EE (a component of the contraceptive pill), diluted in 100 µL of Nujol® for 1 week (EE/PUB group). In the control group, males and females were not treated. Animals were killed (n = 5) after 12 months in the experimental groups. In the senile male in the EE/PUB group, we observed a reduction in testosterone levels and a decrease in the prostatic epithelial thickness, as well as in the thickness of the muscle layer. In addition, an increase in PIN multiplicity and prostatic inflammation was observed. In the senile female in the EE/PUB group, we observed increased testosterone and estradiol levels, an enhanced prostatic epithelial thickness and an increase in the thickness of the muscle layer. Immunohistochemical analysis revealed an increase in positive cells (%) for AR and PCNA in the male prostate and an increase in positive basal cells for p63 in the female prostate of the EE/PUB group. Exposure to EE during puberty resulted in an inhibitory action on the male ventral prostate and an anabolic effect on the female prostate in senile gerbils. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 477-489, 2017.

A Tale of Two Signals: AR and WNT in Development and Tumorigenesis of Prostate and Mammary Gland

Prostate cancer (PCa) is one of the most common cancers and among the leading causes of cancer deaths for men in industrialized countries. It has long been recognized that the prostate is an androgen-dependent organ and PCa is an androgen-dependent disease. Androgen action is mediated by the androgen receptor (AR). Androgen deprivation therapy (ADT) is the standard treatment for metastatic PCa. However, almost all advanced PCa cases progress to castration-resistant prostate cancer (CRPC) after a period of ADT. A variety of mechanisms of progression from androgen-dependent PCa to CRPC under ADT have been postulated, but it remains largely unclear as to when and how castration resistance arises within prostate tumors. In addition, AR signaling may be modulated by extracellular factors among which are the cysteine-rich glycoproteins WNTs. The WNTs are capable of signaling through several pathways, the best-characterized being the canonical WNT/β-catenin/TCF-mediated canonical pathway. Recent studies from sequencing PCa genomes revealed that CRPC cells frequently harbor mutations in major components of the WNT/β-catenin pathway. Moreover, the finding of an interaction between β-catenin and AR suggests a possible mechanism of cross talk between WNT and androgen/AR signaling pathways. In this review, we discuss the current knowledge of both AR and WNT pathways in prostate development and tumorigenesis, and their interaction during development of CRPC. We also review the possible therapeutic application of drugs that target both AR and WNT/β-catenin pathways. Finally, we extend our review of AR and WNT signaling to the mammary gland system and breast cancer. We highlight that the role of AR signaling and its interaction with WNT signaling in these two hormone-related cancer types are highly context-dependent.

Achieving resistance specificity in prostate cancer

Prostate (CaP) cancer is the second-leading cause of cancer-related mortality in men in Western societies. Androgen receptor (AR) signaling is a critical survival pathway for prostate cancer cells, and androgen-deprivation therapy (ADT) remains the principal treatment for patients with locally advanced and metastatic disease. Although a majority of patients initially respond to ADT, most will eventually develop castrate resistance. The recent discovery that AR signaling persists during systemic castration via intratumoral production of androgens led to the development of novel anti-androgen therapies. Although these therapies effectively palliate symptoms and prolong life, metastatic castration-resistant prostate cancer remains incurable. Recent studies suggest that epithelial plasticity, which covers a range of changes in differentiation and cell behavior, with full epithelial integrity at one end and epithelial-mesenchymal Transition (EMT) as the full realization of a plasticity is regulated by microRNAs (miRNAs). MicroRNAs are involved in human tumourigenesis and are aberrantly expressed in CaP cell lines, xenografts and clinical tissues and is associated with enhanced survival signaling, proliferation, migration, invasion, integrin-mediated adhesion, EMT, and drug resistance. Due to the oncogenic or tumor suppressive properties of CaP-related miRNAs, they are likely to be of clinical use as therapeutic targets for prostate cancer treatment in the near future. This review summarizes our current understanding of CaP and castration-recurrent CaP (CR-CaP) to earlier studies that characterized ADT and the molecular mechanisms that facilitate the transition from androgen-stimulated CaP to CR-CaP.

Contribution of Caudal Müllerian Duct Mesenchyme to Prostate Development

A fundamental understanding of prostate development and tissue homeostasis has the high potential to reveal mechanisms for prostate disease initiation and identify novel therapeutic approaches for disease prevention and treatment. Our current understanding of prostate lineage specification stems from the use of developmental model systems that rely upon the embryonic preprostatic urogenital sinus mesenchyme to induce the formation of mature prostate epithelial cells. It is unclear, however, how the urogenital sinus epithelium can derive both adult urethral glands and prostate epithelia. Furthermore, the vast disparity in disease initiation between these two glands highlights key developmental factors that predispose prostate epithelia to hyperplasia and cancer. In this study we demonstrate that the caudal Müllerian duct mesenchyme (CMDM) drives prostate epithelial differentiation and is a key determinant in cell lineage specification between urethral glands and prostate epithelia. Utilizing both human embryonic stem cells and mouse embryonic tissues, we document that the CMDM is capable of inducing the specification of androgen receptor, prostate-specific antigen, NKX3.1, and Hoxb13-positive prostate epithelial cells. These results help to explain key developmental differences between prostate and urethral gland differentiation, and implicate factors secreted by the caudal Müllerian duct as novel targets for prostate disease prevention and treatment.

Comparison of Picrosirius Red Staining With Second Harmonic Generation Imaging for the Quantification of Clinically Relevant Collagen Fiber Features in Histopathology Samples

Stromal collagen alignment has been shown to have clinical significance in a variety of cancers and in other diseases accompanied by fibrosis. While much of the biological and clinical importance of collagen changes has been demonstrated using second harmonic generation (SHG) imaging in experimental settings, implementation into routine clinical pathology practice is currently prohibitive. To translate the assessment of collagen organization into routine pathology workflow, a surrogate visualization method needs to be examined. The objective of the present study was to quantitatively compare collagen metrics generated from SHG microscopy and commonly available picrosirius red stain with standard polarization microscopy (PSR-POL). Each technique was quantitatively compared with established image segmentation and fiber tracking algorithms using human pancreatic cancer as a model, which is characterized by a pronounced stroma with reorganized collagen fibers. Importantly, PSR-POL produced similar quantitative trends for most collagen metrics in benign and cancerous tissues as measured by SHG. We found it notable that PSR-POL detects higher fiber counts, alignment, length, straightness, and width compared with SHG imaging but still correlates well with SHG results. PSR-POL may provide sufficient and additional information in a conventional clinical pathology laboratory for certain types of collagen quantification.

Stromal androgen receptor regulates the composition of the microenvironment to influence prostate cancer outcome

Androgen receptor (AR) signaling in stromal cells is important in prostate cancer, yet the mechanisms underpinning stromal AR contribution to disease development and progression remain unclear. Using patient-matched benign and malignant prostate samples, we show a significant association between low AR levels in cancer associated stroma and increased prostate cancer-related death at one, three and five years post-diganosis, and in tissue recombination models with primary prostate cancer cells that low stromal AR decreases castration-induced apoptosis. AR-regulation was found to be different in primary human fibroblasts isolated from adjacent to cancerous and non-cancerous prostate epithelia, and to represent altered activation of myofibroblast pathways involved in cell cycle, adhesion, migration, and the extracellular matrix (ECM). Without AR signaling, the fibroblast-derived ECM loses the capacity to promote attachment of both myofibroblasts and cancer cells, is less able to prevent cell-matrix disruption, and is less likely to impede cancer cell invasion. AR signaling in prostate cancer stroma appears therefore to alter patient outcome by maintaining an ECM microenvironment inhibitory to cancer cell invasion. This paper provides comprehensive insight into AR signaling in the non-epithelial prostate microenvironment, and a resource from which the prognostic and therapeutic implications of stromal AR levels can be further explored.

Differential ontogenetic exposure to obesogenic environment induces hyperproliferative status and nuclear receptors imbalance in the rat prostate at adulthood

BACKGROUND

Experimental data indicate that high-fat diet (HFD) may alter proliferative activity and prostate health. However, the consequences of HFD exposure during different periods of ontogenetic development on prostate histophysiology remain to be elucidated. Herein, we compare the influence of obesogenic environment (OE) due to maternal obesity and HFD at different periods of life on proliferative activity and nuclear receptors frequency in the rat ventral prostate and a possible relationship with metabolic and hormonal alterations.

METHODS

Male Wistar rats (19 weeks old), treated with balanced chow (Control group-C; 3% high-fat, 3.5 Kcal/g), were compared with those exposed to HFD (20% high-fat, 4.9 kcal/g) during gestation (G-maternal obesity), gestation and lactation (GL), from post-weaning to adulthood (WA), from lactation to adulthood (LA) and from gestation to adulthood (GA). After the experimental period, the ventral prostate lobes were removed and analyzed with different methods.

RESULTS

Metabolic data indicated that G and GL rats became insulin resistant and WA, LA, and GA became insulin resistant and obese. There was a strong inverse correlation between serum testosterone (∼133% lower) and leptin levels (∼467% higher) in WA, LA, and GA groups. Estrogen serum levels increased in GA, and insulin levels increased in all groups, especially in WA (64.8×). OE-groups exhibited prostatic hypertrophy, since prostate weight increased ∼40% in G, GL, LA, and GA and 31% in WA. As indicated by immunohistochemistry, all HFD-groups except G exhibited an increase in epithelial cell proliferation (PCNA-positive) and a decrease in frequency of AR- and ERβ-positive epithelial cells; there was also an increment of ERα-positive stromal cells in comparison with control. Cells containing PPARγ increased in both epithelium and stroma of all OE groups and those expressing LXRα decreased, particularly in groups OE-exposed during gestation (G, GL and GA).

CONCLUSIONS

OE leads to prostate hypertrophy regardless of the period of development and, except when restricted to gestation, leads to a hyperproliferative status which was correlated to downregulation of AR and LXRα and upregulation of ERα and PPARγ signaling.

Hepatocellular carcinoma: Mouse models and the potential roles of proteases

Primary liver cancer is the second most common cause of mortality from cancer. The most common models of hepatocellular carcinoma, which use a chemical and/or metabolic insult, xenograft, or genetic manipulation, are discussed in this review. In the tumour microenvironment lymphocytes, fibroblasts, endothelial cells and antigen presenting cells are important determinants of cell fate. These cells make a range of proteases that modify the biological activity of other proteins, particularly extracellular matrix proteins that alter cell migration of tumour cells, fibroblasts and leucocytes, and chemokines that alter leucocyte migration. The DPP4 family of post-proline peptidase enzymes modifies cell movement and the activities of many bioactive molecules including growth factors and chemokines.

Prenatal exposure to ethinylestradiol alters the morphologic patterns and increases the predisposition for prostatic lesions in male and female gerbils during ageing

Ethinylestradiol (EE) is an endocrine disruptor (ED) which acts as an oestrogen agonist; this compound is known as an oral contraceptive. Male and female rodents exposed to EE during critical time points of development, such as in the prenatal period, show alterations in their reproductive tract during adulthood. Few studies have placed an emphasis on the effects of EE during ageing. Thus, this study had as it's objective the analysis of the morphological and immunohistochemical effects of exposure to EE in the prenatal period on ventral male prostate and female prostate of gerbils (Meriones unguiculatus) during ageing. The animals were exposed to EE (15 μg/kg/day) during the 18-22th days of prenatal life (EE/PRE group), and the analyses were performed when the male and female reached 12 months of age. Our results showed an increase in the development of prostatic intraepithelial neoplasia (PIN), which was observed in the male and female prostate of EE/PRE groups. Immunohistochemistry showed a rise in prostatic epithelial and basal cells immunoreactivity, respectively, and to AR and p63 in the male EE/PRE. There were alterations in the morphological pattern of the prostatic glands and increase in predisposition to emergence of prostatic lesions of both sexes during ageing. Despite male and female having been exposed to the same doses of EE, the "exposure to EE promoted modifications" more accentuated in the male prostate. Thus the male gland is more sensitive to the action of this synthetic oestrogen than the female prostate.

Prostate cancer metastasis: roles of recruitment and reprogramming, cell signal network and three-dimensional growth characteristics

Prostate cancer (PCa) metastasizes to bone and soft tissues, greatly decreasing quality of life, causing bone pain, skeletal complications, and mortality in PCa patients. While new treatment strategies are being developed, the molecular and cellular basis of PCa metastasis and the “cross-talk” between cancer cells and their microenvironment and crucial cell signaling pathways need to be successfully dissected for intervention. In this review, we introduce a new concept of the mechanism of PCa metastasis, the recruitment and reprogramming of bystander and dormant cells (DCs) by a population of metastasis-initiating cells (MICs). We provide evidence that recruited and reprogrammed DCs gain MICs phenotypes and can subsequently metastasize to bone and soft tissues. We show that MICs can also recruit and reprogram circulating tumor cells (CTCs) and this could contribute to cancer cell evolution and the acquisition of therapeutic resistance. We summarize relevant molecular signaling pathways, including androgen receptors (ARs) and their variants and growth factors (GFs) and cytokines that could contribute to the predilection of PCa for homing to bone and soft tissues. To understand the etiology and the biology of PCa and the effectiveness of therapeutic targeting, we briefly summarize the animal and cell models that have been employed. We also report our experience in the use of three-dimensional (3-D) culture and co-culture models to understand cell signaling networks and the use of these attractive tools to conduct drug screening exercises against already-identified molecular targets. Further research into PCa growth and metastasis will improve our ability to target cancer metastasis more effectively and provide better rationales for personalized oncology.

Expression and colocalization of β-catenin and lymphoid enhancing factor-1 in prostate cancer progression

The purpose of this study was to objectively investigate β-catenin and LEF1 abundance, subcellular localization, and colocalization across benign and staged prostate cancer (PCa) specimens. A tissue microarray containing tumor-adjacent histologically benign prostate tissue (BPT; n = 48 patients), high-grade prostatic intraepithelial neoplasia (HGPIN; n = 25), localized PCa (n = 42), aggressive PCa (n = 31), and metastases (n = 22) was stained using multiplexed immunohistochemistry with antibodies toward E-cadherin, β-catenin, and LEF1. Multispectral imaging was used for quantitation, and protein expression and colocalization was evaluated across PCa progression. Stromal nuclear β-catenin abundance was greater in HGPIN and PCa compared with BPT (P < .05 for both), and epithelial nuclear β-catenin abundance was lower in metastatic PCa than in BPT (P < .05 for both). Epithelial and stromal nuclear LEF1 abundance was greater in HGPIN compared with BPT, whereas epithelial nuclear LEF1 was also greater in metastases. The proportion of epithelial and stromal nuclear double-positive β-catenin(+)/LEF1(+) cells was greater in HGPIN compared with BPT. In addition, the proportion of epithelial β-catenin(+)/LEF1(+) cells was greater in localized PCa and metastases compared with BPT. A significant amount of stromal cells were positive for LEF1 but not β-catenin. β-Catenin and LEF1 abundance were negatively correlated in the epithelium (P < .0001) but not the stroma (P > .05). We conclude that β-catenin and LEF1 colocalization is increased in HGPIN and metastasis relative to BPT, suggesting a role for β-catenin/LEF1-mediated transcription in both malignant transformation and metastasis of PCa. Furthermore, our results suggest that LEF1 abundance alone is not a reliable readout for β-catenin activity in prostate tissues.

New transcription factors involved with postnatal ventral prostate gland development in male Wistar rats during the first week

AIMS

The high incidence in men of prostatic diseases, including benign and malignant tumors, makes the understanding of prostate development and biology very important. Understanding the organogenesis of the prostate gland has been a substantial challenge as "prostatic code" is not well defined at the present time. The novelty of this work lies in unveiling new transcription factors (TFs) during neonatal ventral prostate (VP) gland development in male Wistar rats.

MAIN METHODS

The techniques of qRT-PCR and immunohistochemistry have been employed to perform this work while the VP gland was obtained from neonatal rats at day zero (the day of birth) day 3 and 6.

KEY FINDINGS

16 TFs were studied and we found an increased expression of Eya2, Lhrh and Znf142, invariable levels of Znf703 and Dbp, and decreased expression of 11 others at postnatal development day 3 and 6 as compared to day zero. ZNF703 was found by immunohistochemistry in epithelial cells at days 0, 3 and 6. qRT-PCR for Eya2 and Dmrt2 showed the highest and lowest fold change for them respectively, and immunohistochemistry showed that the former is being expressed at the three selected time points while the latter appears to be diminishing with very few cells expressing it until day 6.

SIGNIFICANCE

Results from this work is reporting the role of these TFs for the first time and will significantly contribute to the current understanding of the development and branching morphogenesis of the neonatal VP gland during the first week of postnatal development.

FOXA1 and SOX9 Expression in the Developing Urogenital Sinus of the Tammar Wallaby (Macropus eugenii)

The mammalian prostate is a compact structure in humans but multi-lobed in mice. In humans and mice, FOXA1 and SOX9 play pivotal roles in prostate morphogenesis, but few other species have been examined. We examined FOXA1 and SOX9 in the marsupial tammar wallaby, Macropus eugenii, which has a segmented prostate more similar to human than to mouse. In males, prostatic budding in the urogenital epithelium (UGE) was initiated by day 24 postpartum (pp), but in the female the UGE remained smooth and had begun forming the marsupial vaginal structures. FOXA1 was upregulated in the male urogenital sinus (UGS) by day 51 pp, whilst in the female UGS FOXA1 remained basal. FOXA1 was localised in the UGE in both sexes between day 20 and 80 pp. SOX9 was upregulated in the male UGS at day 21-30 pp and remained high until day 51-60 pp. SOX9 protein was localised in the distal tips of prostatic buds which were highly proliferative. The persistent upregulation of the transcription factors SOX9 and FOXA1 after the initial peak and fall of androgen levels suggest that in the tammar, as in other mammals, these factors are required to sustain prostate differentiation, development and proliferation as androgen levels return to basal levels.

Subcutaneous transplantation promotes organ formation of the fetal rat urogenital sinus

The aim of this study is to develop a novel experimental model of the subcutaneous transplantation of fetal urogenital sinus (UGS) into normal and castrated adult male rats for the pathophysiological investigation of the normal and developing prostate. Fetal UGS obtained from 20-day-old male rat embryos was subcutaneously transplanted into 7-week-old normal and castrated male rats. We observed the growth pattern, histopathological characteristics and immunohistochemical localization of cytokeratin 5 (CK 5), cytokeratin 8 (CK 8) and androgen receptor (AR) in the transplanted tissues. Almost all of the transplanted UGS organs gradually increased in weight over time in the non-castrated recipient animals, and the histopathological observations and immunohistochemical analysis of CK 5 and CK 8 revealed that the morphological changes in the tissues were in accordance with the features of normal prostate development. The histological characteristics included glandular epithelial dominant and stromal dominant area, with an increase in the glandular epithelial dominant areas over time and resemblance among a portion of the transplanted tissues within a certain period during the developmental course to the histopathology of human benign prostatic hyperplasia (BPH). The effects of androgens and resemblance in the immunohistochemical localization pattern changes in AR to that observed in the normal differentiating rat prostate were also noted. We conclude that the subcutaneous space provides an adequate microenvironment for UGS growth.

Overexpression of FGF9 in prostate epithelial cells augments reactive stroma formation and promotes prostate cancer progression

Bone metastasis is the major cause of morbidity and mortality of prostate cancer (PCa). Fibroblast growth factor 9 (FGF9) has been reported to promote PCa bone metastasis. However, the mechanism by which overexpression of FGF9 promotes PCa progression and metastasis is still unknown. Herein, we report that transgenic mice forced to express FGF9 in prostate epithelial cells (F9TG) developed high grade prostatic intraepithelial neoplasia (PIN) in an expression level- and time-dependent manner. Moreover, FGF9/TRAMP bigenic mice (F9TRAMP) grew advanced PCa earlier and had higher frequencies of metastasis than TRAMP littermates. We observed tumor microenvironmental changes including hypercellularity and hyperproliferation in the stromal compartment of F9TG and F9TRAMP mice. Expression of TGFβ1, a key signaling molecule overexpressed in reactive stroma, was increased in F9TG and F9TRAMP prostates. Both in vivo and in vitro data indicated that FGF9 promoted TGFβ1 expression via increasing cJun-mediated signaling. Moreover, in silico analyses showed that the expression level of FGF9 was positively associated with expression of TGFβ1 and its downstream signaling molecules in human prostate cancers. Collectively, our data demonstrated that overexpressing FGF9 in PCa cells augmented the formation of reactive stroma and promoted PCa initiation and progression.

Prostate cancer stroma: an important factor in cancer growth and progression

Reactive stromal changes that occur in different human cancers might play a role in local tumor spreading and progression. Studies done on various human cancers have shown activated stromal cell phenotypes, modified extracellular matrix (ECM) composition, and increased microvessel density. Furthermore, they exhibit biological markers consistent with stroma at the site of wound repair. In prostate cancer, stroma is composed of fibroblasts, myofibroblasts, endothelial cells and immune cells. Predominant cells in the tumorous stroma are, however, fibroblasts/myofibroblasts. They are responsible for the synthesis, deposition and remodeling of the ECM. Epithelial tumorous cells, in interaction with stromal cells and with the help of various molecules of ECM, create a microenvironment suitable for cancer cell proliferation, movement, and differentiation. In this review, we discussed the role of different stromal components in prostate cancer as well as their potential prognostic and therapeutic significance.

Differential gene expression profiling of functionally and developmentally distinct human prostate epithelial populations

BACKGROUND

Human fetal prostate buds appear in the 10th gestational week as solid cords, which branch and form lumens in response to androgen 1. Previous in vivo analysis of prostate epithelia isolated from benign prostatectomy specimens indicated that Epcam⁺ CD44⁻ CD49f(Hi) basal cells possess efficient tubule initiation capability relative to other subpopulations 2. Stromal interactions and branching morphogenesis displayed by adult tubule-initiating cells (TIC) are reminiscent of fetal prostate development. In the current study, we evaluated in vivo tubule initiation by human fetal prostate cells and determined expression profiles of fetal and adult epithelial subpopulations in an effort to identify pathways used by TIC.

METHODS

Immunostaining and FACS analysis based on Epcam, CD44, and CD49f expression demonstrated the majority (99.9%) of fetal prostate epithelial cells (FC) were Epcam⁺ CD44⁻ with variable levels of CD49f expression. Fetal populations isolated via cell sorting were implanted into immunocompromised mice. Total RNA isolation from Epcam⁺ CD44⁻ CD49f(Hi) FC, adult Epcam⁺ CD44⁻ CD49f(Hi) TIC, Epcam⁺ CD44⁺ CD49f(Hi) basal cells (BC), and Epcam⁺ CD44⁻ CD49f(Lo) luminal cells (LC) was performed, followed by microarray analysis of 19 samples using the Affymetrix Gene Chip Human U133 Plus 2.0 Array. Data was analyzed using Partek Genomics Suite Version 6.4. Genes selected showed >2-fold difference in expression and P < 5.00E-2. Results were validated with RT-PCR.

RESULTS

Grafts retrieved from Epcam⁺ CD44⁻ fetal cell implants displayed tubule formation with differentiation into basal and luminal compartments, while only stromal outgrowths were recovered from Epcam- fetal cell implants. Hierarchical clustering revealed four distinct groups determined by antigenic profile (TIC, BC, LC) and developmental stage (FC). TIC and BC displayed basal gene expression profiles, while LC expressed secretory genes. FC had a unique profile with the most similarities to adult TIC. Functional, network, and canonical pathway identification using Ingenuity Pathway Analysis Version 7.6 compiled genes with the highest differential expression (TIC relative to BC or LC). Many of these genes were found to be significantly associated with prostate tumorigenesis.

CONCLUSIONS

Our results demonstrate clustering gene expression profiles of FC and adult TIC. Pathways associated with TIC are known to be deregulated in cancer, suggesting a cell-of-origin role for TIC versus re-emergence of pathways common to these cells in tumorigenesis.

AR function in promoting metastatic prostate cancer

Prostate cancer (PCa) remains a leading cause of cancer-related death in the USA. While localized lesions are effectively treated through radical prostatectomy and/or radiation therapy, treatment for metastatic disease leverages the addiction of these tumors on the androgen receptor (AR) signaling axis for growth and disease progression. Though initially effective, tumors resistant to AR-directed therapeutics ultimately arise (a stage of the disease known as castration-resistant prostate cancer) and are responsible for PCa-specific mortality. Importantly, an abundance of clinical and preclinical evidence strongly implicates AR signaling cascades in the development of metastatic disease in both early and late stages, and thus a concerted effort has been made to delineate the AR-specific programs that facilitate progression to metastatic PCa. A multitude of downstream AR targets as well as critical AR cofactors have been identified which impinge upon both the AR pathway as well as associated metastatic phenotypes. This review will highlight the functional significance of these pathways to disseminated disease and define the molecular underpinnings behind these unique, AR-driven, metastatic signatures.

Stromal androgen receptor roles in the development of normal prostate, benign prostate hyperplasia, and prostate cancer

The prostate is an androgen-sensitive organ that needs proper androgen/androgen receptor (AR) signals for normal development. The progression of prostate diseases, including benign prostate hyperplasia (BPH) and prostate cancer (PCa), also needs proper androgen/AR signals. Tissue recombination studies report that stromal, but not epithelial, AR plays more critical roles via the mesenchymal-epithelial interactions to influence the early process of prostate development. However, in BPH and PCa, much more attention has been focused on epithelial AR roles. However, accumulating evidence indicates that stromal AR is also irreplaceable and plays critical roles in prostate disease progression. Herein, we summarize the roles of stromal AR in the development of normal prostate, BPH, and PCa, with evidence from the recent results of in vitro cell line studies, tissue recombination experiments, and AR knockout animal models. Current evidence suggests that stromal AR may play positive roles to promote BPH and PCa progression, and targeting stromal AR selectively with AR degradation enhancer, ASC-J9, may allow development of better therapies with fewer adverse effects to battle BPH and PCa.

Multiple roles for UDP-glucuronosyltransferase (UGT)2B15 and UGT2B17 enzymes in androgen metabolism and prostate cancer evolution

In the prostate, approximately 50% of androgens are from adrenal steroids, mainly dehydroepiandrosterone (DHEA), its sulfate and androstenedione. These compounds are converted first into testosterone, and then into the active hormone dihydrotestosterone (DHT). After having activated the androgen receptor (AR), DHT is reduced into androstane-3α-DIOL (3α-DIOL) and androsterone (ADT), which are subsequently converted into 2 inactive and easily excretable metabolites: 3α-DIOL-17glucuronide (3α-DIOL-17G) and ADT-3glucuronide (ADT-3G). The formation of these last derivatives through the glucuronidation reaction involves 2 UDP-glucuronosyltransferase (UGT) enzymes, namely UGT2B15 and UGT2B17. The present review article aims at providing a comprehensive view of the physiological and pharmacological importance of these 2 enzymes for the control of androgen homeostasis. We will resume: (i) how UGT2B15 and UGT2B17 contribute to androgen elimination; (ii) how their glucuronidation capacity influences the androgen signaling pathway in prostate cells; (iii) how they contribute to the anti-proliferative properties of AR antagonists in prostate cancer cells; and (iv) how AR and its spliced variants regulate the UGT2B15 and/or UGT2B17 genes expression. Finally, whether the unexploited AR-UGT axis could serve as a prognostic maker or a pharmacological target for novel therapeutics in the treatment of prostate cancer is also discussed. This article is part of a special issue entitled 'Essential role of DHEA'.

Regulation of local steroidogenesis in the brain and in prostate cancer: lessons learned from interdisciplinary collaboration

Sex steroids play critical roles in the regulation of the brain and many other organs. Traditionally, researchers have focused on sex steroid signaling that involves travel from the gonads via the circulation to intracellular receptors in target tissues. This classic concept has been challenged, however, by the growing number of cases in which steroids are synthesized locally and act locally within diverse tissues. For example, the brain and prostate carcinoma were previously considered targets of gonadal sex steroids, but under certain circumstances, these tissues can upregulate their steroidogenic potential, particularly when circulating sex steroid concentrations are low. We review some of the similarities and differences between local sex steroid synthesis in the brain and prostate cancer. We also share five lessons that we have learned during the course of our interdisciplinary collaboration, which brought together neuroendocrinologists and cancer biologists. These lessons have important implications for future research in both fields.

Physiopathological aspects of the Wnt/β-catenin signaling pathway in the male reproductive system

The Wnt/β-catenin signaling pathway controls several biological processes throughout development and adult life. Dysregulation of Wnt/β-catenin signaling underlies a wide range of pathologies in animals and humans, including cancer in different tissues. In this review, we provide an update of the Wnt/β-catenin signaling pathway and the possible roles of the Wnt/β-catenin signaling in the biology of testis, epididymis and prostate. Data from our laboratory suggest the involvement of 17β-estradiol and estrogen receptors (ERs) on the regulation of β-catenin expression in rat Sertoli cells. We also provide emerging evidences of the involvement of Wnt/β-catenin pathway in testis and prostate cancer. Our understanding of the role of Wnt/β-Catenin signaling in male reproductive tissues is still evolving, and several questions are open to be addressed in the future.

Intersection of AHR and Wnt signaling in development, health, and disease

The AHR (aryl hydrocarbon receptor) and Wnt (wingless-related MMTV integration site) signaling pathways have been conserved throughout evolution. Appropriately regulated signaling through each pathway is necessary for normal development and health, while dysregulation can lead to developmental defects and disease. Though both pathways have been vigorously studied, there is relatively little research exploring the possibility of crosstalk between these pathways. In this review, we provide a brief background on (1) the roles of both AHR and Wnt signaling in development and disease, and (2) the molecular mechanisms that characterize activation of each pathway. We also discuss the need for careful and complete experimental evaluation of each pathway and describe existing research that explores the intersection of AHR and Wnt signaling. Lastly, to illustrate in detail the intersection of AHR and Wnt signaling, we summarize our recent findings which show that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced disruption of Wnt signaling impairs fetal prostate development.

Differential effects of estrogen exposure on arylsulfatase B, galactose-6-sulfatase, and steroid sulfatase in rat prostate development

Sulfatase enzymes remove sulfate groups from sulfated steroid hormones, including estrone-sulfate and dehydroepiandrosterone-sulfate, and from sulfated glycosaminoglycans (GAGs), including chondroitin sulfates and heparan sulfate. The enzymes N-acetylgalactosamine-4-sulfatase (arylsulfatase B; ARSB) and N-acetylgalactosamine-6-sulfatase (GALNS), which remove sulfate groups from the sulfated GAGs chondroitin 4-sulfate (C4S) and chondroitin 6-sulfate, respectively, have not been studied in prostate development previously. In this report, the endogenous variation and the impact of exogenous estradiol benzoate on the immunohistochemistry and activity of ARSB and GALNS in post-natal (days 1-30) ventral rat prostate are presented, as well as measurements of steroid sulfatase activity (STS), C4S, total sulfated GAGs, and versican, an extracellular matrix proteoglycan with chondroitin sulfate attachments on days 5 and 30. Findings demonstrate distinct and reciprocal localization of ARSB and GALNS, with ARSB predominant in the stroma and GALNS predominant in the epithelium. Control ARSB activity increased significantly between days 5 and 30, but following estrogen exposure (estradiol benzoate 25 μg in 25 μl sesame oil subcutaneously on days 1, 3, and 5), activity was reduced and the observed increase on day 30 was inhibited. However, estrogen treatment did not inhibit the increase in GALNS activity between days 5 and 30, and reduced STS activity by 50% on both days 5 and 30 compared to vehicle control. Sulfated GAGs, C4S, and the extracellular matrix proteoglycan versican declined between days 5 and 30 in the control, but these declines were inhibited following estrogen. Study findings indicate distinct variation in expression and activity of sulfatases, sulfated GAGs, C4S, and versican in the process of normal prostate development, and disruption of these events by exogenous estrogen.

A novel androgen signalling pathway uses dihydrotestosterone, but not testosterone, to activate the EGF receptor signalling cascade in prostate stromal cells

BACKGROUND AND PURPOSE

Human prostate growth and function are tightly controlled by androgens that are generally thought to exert their effects by regulating gene transcription. However, a rapid, non-genomic steroid action, often involving an elevation of intracellular calcium ([Ca(2+) ]i ), has also been described in a number of cell types. In this study we investigate whether androgens acutely regulate [Ca(2+) ]i in stromal cells derived from the human prostate.

EXPERIMENTAL APPROACH

Human-cultured prostatic stromal cells (HCPSCs) were loaded with the calcium-sensitive fluorophore, fura-2-acetoxymethyl ester (FURA-2AM) (10 μM). Changes in [Ca(2+) ]i in response to the androgens, dihydrotestosterone (DHT) and testosterone, as well as EGF were measured by fluorescence microscopy.

KEY RESULTS

DHT, but not testosterone (0.03-300 nM), elicited concentration-dependent elevations of [Ca(2+) ]i within 1 min of addition. These responses were blocked by the androgen receptor antagonist, flutamide (10 μM); the sarcoplasmic reticulum ATPase pump inhibitor, thapsigargin (1 μM); the inositol trisphosphate receptor inhibitor, 2-aminoethyldiphenyl borate (50 μM) and the PLC inhibitor, U-73122 (1 μM). Responses were also blocked by the L-type calcium channel blocker, nifedipine (1 μM), and by removal of extracellular calcium. A similar transient elevation of [Ca(2+) ]i was elicited by EGF (100 ng·mL(-1) ). The EGF receptor inhibitor, AG 1478 (30 nM), and the MMP inhibitor, marimastat (100 nM), blocked the DHT-induced elevation of [Ca(2+) ]i .

CONCLUSIONS AND IMPLICATIONS

These studies show that DHT elicits an androgen receptor-dependent acute elevation of [Ca(2+) ]i in HCPSC, most likely by activating EGF receptor signalling.

Effect of chronic Sildenafil treatment on the prostate of C57Bl/6 mice

Sildenafil is a potent and selective inhibitor of phosphodiesterase-5 (PDE5) and is considered first-line therapy for erectile dysfunction. Nowadays, Sildenafil is used extensively throughout the world on patients with pulmonary hypertension. However, few studies have evaluated the possible side effects of chronic Sildenafil treatment on the male reproductive system, specifically in the prostate. In the present study, it was demonstrated via morphological and ultrastructural analysis that chronic treatment with Sildenafil induced an enhancement of the glandular activity of the prostate. In addition, mice treated with Sildenafil showed a significant increase in testosterone serum levels. However, no statistically significant differences were observed in nitric oxide serum levels, or in sGC, eNOS, PSA and TGF-β prostatic expression. In conclusion, the present study suggests that chronic use of Sildenafil does not cause evident prostatic damage, and therefore, can be used pharmacologically to treat a variety of disorders.

Androgen-regulated microRNA-135a decreases prostate cancer cell migration and invasion through downregulating ROCK1 and ROCK2

Androgen signaling, via the androgen receptor (AR), is crucial in mediating prostate cancer (PCa) initiation and progression. Identifying new downstream effectors of the androgens/AR pathway will allow a better understanding of these mechanisms and could reveal novel biomarkers and/or therapeutic agents to improve the rate of patient survival. We compared the microRNA expression profiles in androgen-sensitive LNCaP cells stimulated or not with 1 nM R1881 by performing a high-throughput reverse transcriptase-quantitative PCR and found that miR-135a was upregulated. After androgen stimulation, we showed that AR directly activates the transcription of miR-135a2 gene by binding to an androgen response element in the promoter region. Our findings identify miR-135a as a novel effector in androgens/AR signaling. Using xenograft experiments in chick embryos and adult male mice, we showed that miR-135a overexpression decreases in vivo invasion abilities of prostate PC-3 cells. Through in vitro wound-healing migration and invasion assays, we demonstrated that this effect is mediated through downregulating ROCK1 and ROCK2 expression, two genes that we characterized as miR-135a direct target genes. In human surgical samples from prostatectomy, we observed that miR-135a expression was lower in tumoral compared with paired adjacent normal tissues, mainly in tumors classified with a high Gleason score (⩾8). Moreover, miR-135a expression is lower in invasive tumors, showing extraprostatic extension, as compared with intraprostatic localized tumors. In tumor relative to normal glands, we also showed a more frequently higher ROCK1 protein expression determined using a semi-quantitative immunohistochemistry analysis. Therefore, in tumor cells, the lower miR-135a expression could lead to a higher ROCK1 protein expression, which could explain their invasion abilities. The highlighted relationship between miR-135a expression level and the degree of disease aggressiveness suggests that miR-135a may be considered as a prognostic marker in human PCa.

Finasteride treatment alters tissue specific androgen receptor expression in prostate tissues

BACKGROUND

Normal and pathologic growth of the prostate is dependent on the synthesis of dihydrotestosterone (DHT) from testosterone by 5α-reductase. Finasteride is a selective inhibitor of 5α-reductase 2, one isozyme of 5α-reductase found in abundance in the human prostate. The objective of this study was to investigate the effects of finasteride on androgen receptor expression and tissue morphology in human benign prostatic hyperplasia specimens.

METHODS

Patients undergoing transurethral resection of the prostate and either treated or not treated with finasteride between 2004 and 2010 at the University of Wisconsin-Hospital were retrospectively identified using an institutional database. Prostate specimens from each patient were triple-stained for androgen receptor, prostate-specific antigen, and basal marker cytokeratin 5. Morphometric analysis was performed using the multispectral imaging, and results were compared between groups of finasteride treated and non-treated patients.

RESULTS

Epithelial androgen receptor but not stromal androgen receptor expression was significantly lower in patients treated with finasteride than in non-treated patients. Androgen receptor-regulated prostate-specific antigen was not significantly decreased in finasteride-treated patients. Significant luminal epithelial atrophy and basal cell hyperplasia were prevalent in finasteride treated patients. Epithelial androgen receptor expression was highly correlated to the level of luminal epithelial atrophy.

CONCLUSIONS

In this study, finasteride decreased the expression of epithelial androgen receptor in a tissue specific manner. The correlation between epithelial androgen receptor and the extent of luminal epithelial atrophy suggests that epithelial androgen receptor may be directly regulating the atrophic effects observed with finasteride treatment.

Characterisation of the androgen regulation of glycine N-methyltransferase in prostate cancer cells

The development and growth of prostate cancer is dependent on androgens; thus, the identification of androgen-regulated genes in prostate cancer cells is vital for defining the mechanisms of prostate cancer development and progression and developing new markers and targets for prostate cancer treatment. Glycine N-methyltransferase (GNMT) is a S-adenosylmethionine-dependent methyltransferase that has been recently identified as a novel androgen-regulated gene in prostate cancer cells. Although the importance of this protein in prostate cancer progression has been extensively addressed, little is known about the mechanism of its androgen regulation. Here, we show that GNMT expression is stimulated by androgen in androgen receptor (AR) expressing cells and that the stimulation occurs at the mRNA and protein levels. We have identified an androgen response element within the first exon of the GNMT gene and demonstrated that AR binds to this element in vitro and in vivo. Together, these studies identify GNMT as a direct transcriptional target of the AR. As this is an evolutionarily conserved regulatory element, this highlights androgen regulation as an important feature of GNMT regulation.

Development of a reactive stroma associated with prostatic intraepithelial neoplasia in EAF2 deficient mice

ELL-associated factor 2 (EAF2) is an androgen-responsive tumor suppressor frequently deleted in advanced prostate cancer that functions as a transcription elongation factor of RNA Pol II through interaction with the ELL family proteins. EAF2 knockout mice on a 129P2/OLA-C57BL/6J background developed late-onset lung adenocarcinoma, hepatocellular carcinoma, B-cell lymphoma and high-grade prostatic intraepithelial neoplasia. In order to further characterize the role of EAF2 in the development of prostatic defects, the effects of EAF2 loss were compared in different murine strains. In the current study, aged EAF2^−/− mice on both the C57BL/6J and FVB/NJ backgrounds exhibited mPIN lesions as previously reported on a 129P2/OLA-C57BL/6J background. In contrast to the 129P2/OLA-C57BL/6J mixed genetic background, the mPIN lesions in C57BL/6J and FVB/NJ EAF2^−/− mice were associated with stromal defects characteristic of a reactive stroma and a statistically significant increase in prostate microvessel density. Stromal inflammation and increased microvessel density was evident in EAF2-deficient mice on a pure C57BL/6J background at an early age and preceded the development of the histologic epithelial hyperplasia and neoplasia found in the prostates of older EAF2^−/− animals. Mice deficient in EAF2 had an increased recovery rate and a decreased overall response to the effects of androgen deprivation. EAF2 expression in human cancer was significantly down-regulated and microvessel density was significantly increased compared to matched normal prostate tissue; furthermore EAF2 expression was negatively correlated with microvessel density. These results suggest that the EAF2 knockout mouse on the C57BL/6J and FVB/NJ genetic backgrounds provides a model of PIN lesions associated with an altered prostate microvasculature and reactive stromal compartment corresponding to that reported in human prostate tumors.

Disruption of prostate epithelial differentiation pathways and prostate cancer development

One of the foremost problems in the prostate cancer (PCa) field is the inability to distinguish aggressive from indolent disease, which leads to difficult prognoses and thousands of unnecessary surgeries. This limitation stems from the fact that the mechanisms of tumorigenesis in the prostate are poorly understood. Some genetic alterations are commonly reported in prostate tumors, including upregulation of Myc, fusion of Ets genes to androgen-regulated promoters, and loss of Pten. However, the specific roles of these aberrations in tumor initiation and progression are poorly understood. Likewise, the cell of origin for PCa remains controversial and may be linked to the aggressive potential of the tumor. One important clue is that prostate tumors co-express basal and luminal protein markers that are restricted to their distinct cell types in normal tissue. Prostate epithelium contains layer-specific stem cells as well as rare bipotent cells, which can differentiate into basal or luminal cells. We hypothesize that the primary oncogenic cell of origin is a transient-differentiating bipotent cell. Such a cell must maintain tight temporal and spatial control of differentiation pathways, thus increasing its susceptibility for oncogenic disruption. In support of this hypothesis, many of the pathways known to be involved in prostate differentiation can be linked to genes commonly altered in PCa. In this article, we review what is known about important differentiation pathways (Myc, p38MAPK, Notch, PI3K/Pten) in the prostate and how their misregulation could lead to oncogenesis. Better understanding of normal differentiation will offer new insights into tumor initiation and may help explain the functional significance of common genetic alterations seen in PCa. Additionally, this understanding could lead to new methods for classifying prostate tumors based on their differentiation status and may aid in identifying more aggressive tumors.

Activation of FGF2-FGFR signaling in the castrated mouse prostate stimulates the proliferation of basal epithelial cells

The prostate gland is unique in that it undergoes rapid regression following castration but regenerates completely once androgens are replaced. Residual ductal components play an important role in the regeneration of a fully functional prostate. In this study, to examine how androgen status affects prostate structure and components, we conducted histopathological studies of the involuted and regenerated mouse dorsolateral prostate (DLP). In the castrated mouse DLP, the number of luminal epithelial cells decreased in a time-dependent manner. On Day 14 postandrogen replacement, the number of luminal epithelial cells was completely restored to the baseline level. In contrast, the number of basal epithelial cells gradually increased in the castrated mouse prostate. The Ki67-labeling index of prostate basal epithelial cells was significantly increased after castration. The number of basal epithelial cells decreased to baseline after androgen replacement. After castration, mRNA expression levels of specific growth factors, such as Fgf2, Fgf7, Hgf, Tgfa, and Tgfb, were relatively abundant in whole mouse DLPs. In organ culture experiments, basal epithelial proliferation was recapitulated in the absence of dihydrotestosterone (DHT). The proliferation of basal epithelial cells in the absence of DHT was suppressed by treatment with an FGF receptor inhibitor (PD173074). Moreover, FGF2 treatment directly stimulated the proliferation of basal epithelial cells. Taken together, these data indicated that the FGF2-FGF receptor signal cascade in the prostate gland may be one of the pathways stimulating the proliferation of basal epithelial cells in the absence of androgens.

Androgen signaling disruption during fetal and postnatal development affects androgen receptor and connexin 43 expression and distribution in adult boar prostate

To date, limited knowledge exists regarding the role of the androgen signaling during specific periods of development in the regulation of androgen receptor (AR) and connexin 43 (Cx43) in adult prostate. Therefore, in this study we examined mRNA and protein expression, and tissue distribution of AR and Cx43 in adult boar prostates following fetal (GD20), neonatal (PD2), and prepubertal (PD90) exposure to an antiandrogen flutamide (50 mg/kg bw). In GD20 and PD2 males we found the reduction of the luminal compartment, inflammatory changes, decreased AR and increased Cx43 expression, and altered localization of both proteins. Moreover, enhanced apoptosis and reduced proliferation were detected in the prostates of these animals. In PD90 males the alterations were less evident, except that Cx43 expression was markedly upregulated. The results presented herein indicate that in boar androgen action during early fetal and neonatal periods plays a key role in the maintenance of normal phenotype and functions of prostatic cells at adulthood. Furthermore, we demonstrated that modulation of Cx43 expression in the prostate could serve as a sensitive marker of hormonal disruption during different developmental stages.

Metabolic reprogramming and validation of hyperpolarized 13C lactate as a prostate cancer biomarker using a human prostate tissue slice culture bioreactor

BACKGROUND

The treatment of prostate cancer has been impeded by the lack of both clinically relevant disease models and metabolic markers that track tumor progression. Hyperpolarized (HP) (13) C MR spectroscopy has emerged as a new technology to investigate the metabolic shifts in prostate cancer. In this study, we investigate the glucose reprogramming using HP (13) C pyruvate MR in a patient-derived prostate tissue slice culture (TSC) model.

METHODS

The steady-state metabolite concentrations in freshly excised human prostate TSCs were assessed and compared to those from snap-frozen biopsy samples. The TSCs were then applied to a perfused cell (bioreactor) platform, and the bioenergetics and the dynamic pyruvate flux of the TSCs were investigated by (31) P and HP (13) C MR, respectively.

RESULTS

The prostate TSCs demonstrated steady-state glycolytic and phospholipid metabolism, and bioenergetics that recapitulate features of prostate cancer in vivo. (13) C spectra following injection of HP (13) C pyruvate showed significantly increased pyruvate to lactate flux in malignant as compared to the benign prostate TSCs. This increased flux in the malignant prostate TSCs correlated with both increased expression of monocarboxylate transporters (MCT) and activity of lactate dehydrogenase (LDH).

CONCLUSIONS

We provide the first mechanistic evidence for HP (13) C lactate as a prostate cancer biomarker in living human tissues, critical for the interpretation of in vivo studies. More broadly, the clinically relevant metabolic model system in combination with HP MR can facilitate the identification of clinically translatable biomarkers of prostate cancer presence, aggressiveness, and treatment response.

Nuclear receptors and endobiotics glucuronidation: the good, the bad, and the UGT

The recent progresses in molecular biology and pharmacology approaches allowed the characterization of a series of nuclear receptors (NRs) as efficient regulators of uridine diphosphate glucuronosyltransferase (UGT) genes activity. These regulatory processes ensure an optimized UGT expression in response to specific endo- and/or exogenous stimuli. Many of these NRs are activated by endobiotics that also are substrates for UGTs. Thus, by activating their receptors, these endogenous substances control their own conjugation, leading to the concept that glucuronidation is an important part of feed-forward/feedback mechanisms by which bioactive molecules control their own concentrations. On the other hand, numerous studies have established the pharmacological relevance of NR-UGT regulatory pathways in the response to therapeutic ligands. The present review article aims at providing a comprehensive view of the physiological and pharmacological importance of the NR regulation of the expression and activity of endobiotics-conjugating UGT enzymes. Selected examples will illustrate how the organism profits from the feed-forward/feedback mechanisms involving NR-UGT pathways, but also how such regulatory processes are involved in the initiation and/or progression of several pathological situations. Finally, we will discuss how the present pharmacopeia involves NR-dependent regulation of endobiotics glucuronidation, and whether the unexploited NR-UGT axes could serve as pharmacological targets for novel therapeutics to restore endobiotics homeostasis.

Role of the EpCAM (CD326) in prostate cancer metastasis and progression

Despite significant advances in surgery, radiotherapy and chemotherapy to treat prostate cancer (CaP), many patients die of secondary disease (metastases). Current therapeutic approaches are limited, and there is no cure for metastatic castration-resistant prostate cancer (CRPC). Epithelial cell adhesion molecule (EpCAM, also known as CD326) is a transmembrane glycoprotein that is highly expressed in rapidly proliferating carcinomas and plays an important role in the prevention of cell-cell adhesion, cell signalling, migration, proliferation and differentiation. Stably and highly expressed EpCAM has been found in primary CaP tissues, effusions and CaP metastases, making it an ideal candidate of tumour-associated antigen to detect metastasis of CaP cells in the circulation as well as a promising therapeutic target to control metastatic CRPC disease. In this review, we discuss the implications of the newly identified roles of EpCAM in terms of its diagnostic and metastatic relevance to CaP. We also summarize EpCAM expression in human CaP and EpCAM-mediated signalling pathways in cancer metastasis. Finally, emerging and innovative approaches to the management of the disease and expanding potential therapeutic applications of EpCAM for targeted strategies in future CaP therapy will be explored.

Prostate cancer cell telomere length variability and stromal cell telomere length as prognostic markers for metastasis and death

Current prognostic indicators are imperfect predictors of outcome in men with clinically localized prostate cancer. Thus, tissue-based markers are urgently needed to improve treatment and surveillance decision-making. Given that shortened telomeres enhance chromosomal instability and such instability is a hallmark of metastatic lesions, we hypothesized that alterations in telomere length in the primary cancer would predict risk of progression to metastasis and prostate cancer death. To test this hypothesis, we conducted a prospective cohort study of 596 surgically treated men who participated in the ongoing Health Professionals Follow-up Study. Men who had the combination of more variable telomere length among prostate cancer cells (cell-to-cell) and shorter telomere length in prostate cancer-associated stromal (CAS) cells were substantially more likely to progress to metastasis or die of their prostate cancer. These findings point to the translational potential of this telomere biomarker for prognostication and risk stratification for individualized therapeutic and surveillance strategies.

SIGNIFICANCE

In this prospective study, the combination of more variable telomere length among cancer cells and shorter telomere length in CAS cells was strongly associated with progression to metastasis and prostate cancer death, pointing to the translational potential for prognostication and risk stratifi cation for individualized therapeutic and surveillance strategies.