Novel imaging of the prostate reveals spontaneous gland contraction and excretory duct quiescence together with different drug effects.

Prostate carcinoma and benign prostate hyperplasia (BPH) with associated lower urinary tract symptoms (LUTS) are among the most prevalent and clinically relevant diseases in men. BPH is characterized by an enlargement of prostate tissue associated with increased tone of smooth muscle cells (SMCs) which surround the single glands composing the prostate. Secretions of the glands leave the prostate through local excretory ducts during the emission phase of ejaculation. Pharmacological treatment of BPH suggests different local drug targets based on reduction of prostate smooth muscle tone as the main effect and disturbed ejaculation as a common side effect. This highlights the need for detailed investigation of single prostate glands and ducts. We combined structural and functional imaging techniques-notably, clear lipid-exchanged, acrylamide-hybridized rigid imaging/immunostaining/ in situ hybridization-compatible tissue-hydrogel (CLARITY) and time-lapse imaging-and defined glands and ducts as distinct SMC compartments in human and rat prostate tissue. The single glands of the prostate (comprising the secretory part) are characterized by spontaneous contractions mediated by the surrounding SMCs, whereas the ducts (excretory part) are quiescent. In both SMC compartments, phosphodiesterase (PDE)-5 is expressed. PDE5 inhibitors have recently emerged as alternative treatment options for BPH. We directly visualized that the PDE5 inhibitors sildenafil and tadalafil act by reducing spontaneous contractility of the glands, thereby reducing the muscle tone of the organ. In contrast, the ductal (excretory) system and thus the prostate's contribution to ejaculation is unaffected by PDE5 inhibitors. Our differentiated imaging approach reveals new details about prostate function and local drug actions and thus may support clinical management of BPH.-Kügler, R., Mietens, A., Seidensticker, M., Tasch, S., Wagenlehner, F. M., Kaschtanow, A., Tjahjono, Y., Tomczyk, C. U., Beyer, D., Risbridger, G. P., Exintaris, B., Ellem, S. J., Middendorff, R. Novel imaging of the prostate reveals spontaneous gland contraction and excretory duct quiescence together with different drug effects.

Treating prostate cancer: a rationale for targeting local oestrogens.

Prostate cancer is the most commonly diagnosed cancer and the second most common cause of cancer-related death in men, and benign prostatic hyperplasia is the most common benign condition known to occur in ageing men. Oestrogen has been implicated in the development of prostate cancer, and offers a promising new avenue for treatment. Despite this, the role of oestrogens in the prostate is complex. This Perspective presents a rationale for a targeted approach for the treatment of prostate disease through the use of selective oestrogen-receptor modulators in conjunction with contemporary androgen-ablation therapy.

A pro-tumourigenic loop at the human prostate tumour interface orchestrated by oestrogen, CXCL12 and mast cell recruitment.

Prostate cancer is hormone-dependent and regulated by androgens as well as oestrogens. The tumour microenvironment also provides regulatory control, but the balance and interplay between androgens and oestrogens at the human prostate tumour interface is unknown. This study reveals a central and dominant role for oestrogen in the microenvironment, fuelling a pro-tumourigenic loop of inflammatory cytokines involving recruitment of mast cells by carcinoma-associated fibroblasts (CAFs). Mast cell numbers were increased in human PCa clinical specimens, specifically within the peritumoural stroma. Human mast cells were also shown to express ERα and ERß, with oestradiol directly stimulating mast cell proliferation and migration as well as altered cytokine/chemokine expression. There was a significant shift in the oestrogen:androgen balance in CAFs versus normal prostatic fibroblasts (NPFs), with a profound increase to ER:AR expression. Androgen signalling is also reduced in CAFs, while ERα and ERß transcriptional activity is not, allowing oestrogen to dictate hormone action in the tumour microenvironment. Gene microarray analyses identified CXCL12 as a major oestrogen-driven target gene in CAFs, and CAFs recruit mast cells via CXCL12 in a CXCR4-dependent manner. Collectively, these data reveal multicellular oestrogen action in the tumour microenvironment and show dominant oestrogen, rather than androgen, signalling at the prostatic tumour interface.

Aromatase transgenic upregulation modulates basal cardiac performance and the response to ischemic stress in male mice.

Estrogen in females is conventionally considered a cardioprotective influence, but a role for estrogen in male cardioprotection has yet to be defined. Estrogen biosynthesis from testosterone is regulated by aromatase. Aromatase has recently been shown to be expressed in the adult heart, although little is known about its involvement in the regulation of myocardial function and stress responses. The goal of this study was to determine whether upregulation of tissue aromatase expression could improve ischemic resilience in male hearts. Isolated hearts from male transgenic aromatase-overexpressing (AROM(+); high estrogen, low testosterone) mice and wild-type (WT) mice (12 wk) were Langendorff perfused and subjected to ischemia-reperfusion (25 min ischemia and 60 min of reperfusion). Basal systolic function was lower in AROM(+) hearts (dP/dtmax: 4,121 ± 255 vs. 4,992 ± 283 mmHg/s, P < 0.05) and associated with augmented Akt phosphorylation, consistent with a suppressor action of estrogen on contractility. Ischemic contracture was attenuated in AROM(+) hearts (43 ± 3 vs. 55 ± 4 mmHg, P < 0.05), yet AROM(+) hearts were more arrhythmic in early reperfusion. At the end of 60 min of reperfusion, AROM(+) systolic functional recovery was lower (left ventricular developed pressure: 39 ± 6 vs. 56 ± 5 %basal, P < 0.05) and diastolic dysfunction was accentuated (36 ± 4 vs. 24 ± 2 mmHg, P < 0.05). This is the first study to show that in vivo aromatase upregulation modulates basal cardiac performance and the response to ischemic stress. These data suggest that while chronic exposure to enhanced estrogenic influence may have benefits in limiting ischemic contracture severity, acute functional recovery in reperfusion is compromised. A temporally targeted, tissue-specific intervention combining aromatase treatment with inotropic support may offer therapeutic potential for men and women.

Brief report: a bioassay to identify primary human prostate cancer repopulating cells.

Cancer cells are heterogeneous in both their phenotypes and ability to promote tumor growth and spread. Xenografting is used to identify the most highly capable cells of regenerating tumors, referred to as cancer repopulating cells. Because prostate cancers (PCa's) rarely grow as xenografts, indentifying PCa repopulating cells has not been possible. Here, we report improved methods to xenograft localized primary PCa tissues using chimeric grafts with neonatal mouse mesenchyme. Xenograft survival of tumor tissue was significantly increased by neonatal mesenchyme (six of six patients, 66% of grafts, versus four of six patients, 41% of grafts) and doubled the proliferation index of xenografted cancer cells. When applied to isolated PCa cells, neonatal mesenchyme effectively reconstituted PCa's and increased xenograft survival (four of nine patients; 32% of grafts with mesenchyme and 0% without), and supported active cancer cell proliferation. Using this assay, we showed that unfractionated α2ß1integrin(hi) and α2ß1integrin(lo) cells from primary localized PCa's demonstrated tumor formation at comparable rates, similar to previous reports using metastatic specimens. Thus, this new protocol efficiently established tumors and enabled proliferative expansion of both intact tumor tissue and fractionated cancer cells, providing a bioassay to identify and therapeutically target PCa repopulating cells.

Oxytocin receptor antagonists as a novel pharmacological agent for reducing smooth muscle tone in the human prostate.

Pharmacotherapies for the treatment of Benign Prostatic Hyperplasia (BPH) are targeted at reducing cellular proliferation (static component) or reducing smooth muscle tone (dynamic component), but response is unpredictable and many patients fail to respond. An impediment to identifying novel pharmacotherapies is the incomplete understanding of paracrine signalling. Oxytocin has been highlighted as a potential paracrine mediator of BPH. To better understand oxytocin signalling, we investigated the effects of exogenous oxytocin on both stromal cell proliferation, and inherent spontaneous prostate contractions using primary models derived from human prostate tissue. We show that the Oxytocin Receptor (OXTR) is widely expressed in the human prostate, and co-localises to contractile cells within the prostate stroma. Exogenous oxytocin did not modulate prostatic fibroblast proliferation, but did significantly (p < 0.05) upregulate the frequency of spontaneous contractions in prostate tissue, indicating a role in generating smooth muscle tone. Application of atosiban, an OXTR antagonist, significantly (p < 0.05) reduced spontaneous contractions. Individual tissue responsiveness to both exogenous oxytocin (R2 = 0.697, p < 0.01) and atosiban (R2 = 0.472, p < 0.05) was greater in tissue collected from older men. Overall, our data suggest that oxytocin is a key regulator of inherent spontaneous prostate contractions, and targeting of the OXTR and associated downstream signalling is an attractive prospect in the development of novel BPH pharmacotherapies.

Mast Cell-Derived SAMD14 Is a Novel Regulator of the Human Prostate Tumor Microenvironment.

Mast cells (MCs) are important cellular components of the tumor microenvironment and are significantly associated with poor patient outcomes in prostate cancer and other solid cancers. The promotion of tumor progression partly involves heterotypic interactions between MCs and cancer-associated fibroblasts (CAFs), which combine to potentiate a pro-tumor extracellular matrix and promote epithelial cell invasion and migration. Thus far, the interactions between MCs and CAFs remain poorly understood. To identify molecular changes that may alter resident MC function in the prostate tumor microenvironment, we profiled the transcriptome of human prostate MCs isolated from patient-matched non-tumor and tumor-associated regions of fresh radical prostatectomy tissue. Transcriptomic profiling revealed a distinct gene expression profile of MCs isolated from prostate tumor regions, including the downregulation of SAMD14, a putative tumor suppressor gene. Proteomic profiling revealed that overexpression of SAMD14 in HMC-1 altered the secretion of proteins associated with immune regulation and extracellular matrix processes. To assess MC biological function within a model of the prostate tumor microenvironment, HMC-1-SAMD14+ conditioned media was added to co-cultures of primary prostatic CAFs and prostate epithelium. HMC-1-SAMD14+ secretions were shown to reduce the deposition and alignment of matrix produced by CAFs and suppress pro-tumorigenic prostate epithelial morphology. Overall, our data present the first profile of human MCs derived from prostate cancer patient specimens and identifies MC-derived SAMD14 as an important mediator of MC phenotype and function within the prostate tumor microenvironment.

Increased endogenous estrogen synthesis leads to the sequential induction of prostatic inflammation (prostatitis) and prostatic pre-malignancy.

Prostatitis causes substantial morbidity to men, through associated urinary symptoms, sexual dysfunction, and pelvic pain; however, 90% to 95% of cases have an unknown etiology. Inflammation is associated with the development of carcinoma, and, therefore, it is imperative to identify and study the causes of prostatitis to improve our understanding of this disease and its role in prostate cancer. As estrogens cause prostatic inflammation, here we characterize the murine prostatic phenotype induced by elevated endogenous estrogens due to aromatase overexpression (AROM+). Early-life development of the AROM+ prostate was normal; however, progressive changes culminated in chronic inflammation and pre-malignancy. The AROM+ prostate was smaller at puberty compared with wild-type controls. Mast cell numbers were significantly increased at puberty and preceded chronic inflammation, which emerged by 40 weeks of age and was characterized by increased mast cell, macrophage, neutrophil, and T-lymphocyte numbers. The expression of key inflammatory mediators was also significantly altered, and premalignant prostatic intraepithelial neoplasia lesions emerged by 52 weeks of age. Taken together, these data link estrogens to prostatitis and premalignancy in the prostate, further implicating a role for estrogen in prostate cancer. These data also establish the AROM+ mouse as a novel, non-bacterial model for the study of prostatitis.

Estrogen-regulated development and differentiation of the prostate.

Both androgens and estrogens play a significant role in the prostate and are critical for normal prostate growth and development, as well as the maintenance of adult prostatic homeostasis throughout life. It is the balance of these two hormones, rather than each individually, that is important for prostatic development and differentiation. Estrogen action is mediated by the estrogen receptors, ERalpha and ERbeta. ERalpha is expressed throughout the prostatic tissue during fetal and early neonatal life, and if activated inappropriately, produces late-life disease, including inflammation and emergence of pre-malignant pathologies. In contrast, ERbeta expression is initiated after ERalpha, is localized primarily to the epithelium, and appears to be important during later periods of development such as puberty and adulthood, acting to regulate cellular proliferation and differentiation in the adult tissue. Therefore, there is also a spatial and temporal balance between ERalpha and ERbeta that is critical for development. Together with the shifting balance between androgens and estrogens themselves, the subtle, yet critical, balance between the activity of ERalpha and ERbeta is what ultimately determines the response of the prostate to estrogen, and is crucial for prostate health.

Essential role for estrogen receptor beta in stromal-epithelial regulation of prostatic hyperplasia.

Estrogens, acting via estrogen receptors (ER) alpha and beta, exert direct and indirect actions on prostate growth and differentiation. Previous studies using animal models to determine the role of ERbeta in the prostate have been problematic because the centrally mediated response to estrogen results in reduced androgen levels and prostatic epithelial regression, potentially masking any direct effects via ERbeta. This study overcomes this problem by using the estrogen-deficient aromatase knockout mouse and tissue recombination to provide new insight into estrogen action on prostate growth and pathology. Homo- and heterotypic aromatase knockout tissue recombinants revealed stromal aromatase deficiency induced hyperplasia in normal prostatic epithelium due to disruption of paracrine interaction between stroma and epithelia. Treatment of tissue recombinants with an ERbeta-specific agonist demonstrated that stimulation of ERbeta elicits antiproliferative responses in epithelium that are not influenced by alterations to systemic androgen levels or the activation of ERalpha. Additionally, work performed with intact aromatase knockout mice demonstrated that the administration of an ERbeta-specific agonist ablated preexisting prostatic epithelial hyperplasia, whereas an ERalpha-specific agonist did not. Therefore, failed activation of ERbeta, resulting from local stromal aromatase deficiency, in conjunction with increased androgen levels, results in increased epithelial cell proliferation and prostatic hyperplasia. These data demonstrate essential and beneficial effects of estrogens that are necessary for normal growth of the prostate and distinguishes them from those that adversely alter prostate growth and differentiation. This highlights the potential of selective estrogen-receptor modulators, rather than aromatase inhibitors, for the management of dysregulated prostate growth.

Age Related Differences in Responsiveness to Sildenafil and Tamsulosin are due to Myogenic Smooth Muscle Tone in the Human Prostate.

Lower urinary tract symptoms (LUTS) due to Benign Prostatic Hyperplasia (BPH) are highly prevalent in older men, having a profound impact on patient quality of life. Current therapeutics for BPH/LUTS target neurogenic smooth muscle tone, but response is unpredictable and many patients fail to respond. Spontaneous myogenic tone is another component of smooth muscle contractility that is uncharacterized in human prostate. To better understand and improve the predictability of patient response, we defined myogenic contractility using human prostate specimens and examined the effect of existing therapeutics. We show that myogenic activity is present in the human prostate with the frequency of contractions in transition zone (TZ) specimens from BPH diagnosed patients approximately 160% greater than matched controls. α1-adrenoreceptor antagonists (Tamsulosin) and PDE5 inhibitors (Sildenafil) both significantly reduced myogenic contractile parameters, including frequency, with notable interpatient variability. Tamsulosin was more effective in older patients (R2 = 0.36, p < 0.01) and men with larger prostate volumes (R2 = 0.41, p < 0.05), while Sildenafil was more effective in younger men (R2 = 0.45, p < 0.05). As myogenic tone is significantly increased in BPH, therapeutics targeting this mechanism used with reference to patient characteristics could improve clinical outcomes and better predict patient response.

Local aromatase expression in human prostate is altered in malignancy.

Tissue-specific aromatase production is significant in breast cancer and osteoporosis. Prostatic aromatase expression has been equivocal, and any local actions of estrogens are considered secondary to centrally mediated androgen suppression. We examine local aromatase expression and estrogen biosynthesis in the human prostate. Pure samples of stroma and epithelia from biopsy tissues were isolated by laser capture microdissection. Aromatase protein was detected by Western blot analysis, mRNA by RT-PCR, and enzyme activity by tritiated water assay, whereas promoter use was examined by real-time PCR. In nonmalignant prostate tissues, aromatase mRNA expression was absent from epithelium, but did localize to stroma. Presence of protein was confirmed, and expression was driven by promoter PII. Aromatase was expressed and active in LNCaP, PC3, and DU145 cells in addition to microdissected epithelial tumor cells; benign prostate epithelial cells showed no expression or activity. Promoter use in LNCaP and microdissected tumor cells was via PII, whereas PC3 and DU145 cells used promoter I.4. This study demonstrates local estrogen biosynthesis in prostate-induced aromatase gene expression in malignancy and potential alteration of aromatase promoter use with disease progression. These data provide a basis for continued investigation of local estrogen production and its potential role in prostate disease.

In vitro modeling of the prostate cancer microenvironment.

Prostate cancer is the most commonly diagnosed malignancy in men and advanced disease is incurable. Model systems are a fundamental tool for research and many in vitro models of prostate cancer use cancer cell lines in monoculture. Although these have yielded significant insight they are inherently limited by virtue of their two-dimensional (2D) growth and inability to include the influence of tumour microenvironment. These major limitations can be overcome with the development of newer systems that more faithfully recreate and mimic the complex in vivo multi-cellular, three-dimensional (3D) microenvironment. This article presents the current state of in vitro models for prostate cancer, with particular emphasis on 3D systems and the challenges that remain before their potential to advance our understanding of prostate disease and aid in the development and testing of new therapeutic agents can be realised.

A bioengineered microenvironment to quantitatively measure the tumorigenic properties of cancer-associated fibroblasts in human prostate cancer.

Stromal-epithelial cell interactions play an important role in cancer and the tumor stroma is regarded as a therapeutic target. In vivo xenografting is commonly used to study cellular interactions not mimicked or quantified in conventional 2D culture systems. To interrogate the effects of tumor stroma (cancer-associated fibroblasts or CAFs) on epithelia, we created a bioengineered microenvironment using human prostatic tissues. Patient-matched CAFs and non-malignant prostatic fibroblasts (NPFs) from men with moderate (Gleason 7) and aggressive (Gleason 8-9 or castrate-resistant) prostate cancer were cultured with non-tumorigenic BPH-1 epithelial cells. Changes in the morphology, motility and phenotype of BPH-1 cells in response to CAFs and NPFs were analyzed using immunofluorescence and quantitative cell morphometric analyses. The matrix protein gene expression of CAFs, with proven tumorigenicity in vivo, had a significantly different gene expression profile of matrix proteins compared to patient matched NPFs. In co-culture with CAFs (but not NPFs), BPH-1 cells had a more invasive, elongated phenotype with increased motility and a more directed pattern of cell migration. CAFs from more aggressive tumors (Gleason 8-9 or CRPC) were not quantitatively different to moderate grade CAFs. Overall, our bioengineered microenvironment provides a novel 3D in vitro platform to systematically investigate the effects of tumor stroma on prostate cancer progression.

Estrogen receptor ß activation impairs prostatic regeneration by inducing apoptosis in murine and human stem/progenitor enriched cell populations.

Androgen depletion is the primary treatment for prostate disease; however, it fails to target residual castrate-resistant cells that are regenerative and cells of origin of prostate cancer. Estrogens, like androgens, regulate survival in prostatic cells, and the goal of this study was to determine the advantages of selective activation of estrogen receptor ß (ERß) to induce cell death in stem cells that are castrate-resistant. Here we show two cycles of short-term ERß agonist (8ß-VE2) administration this treatment impairs regeneration, causing cystic atrophy that correlates with sustained depletion of p63+ basal cells. Furthermore, agonist treatment attenuates clonogenicity and self-renewal of murine prostatic stem/progenitor cells and depletes both murine (Lin(-)Sca1(+)CD49f(hi)) and human (CD49f(hi)Trop2(hi)) prostatic basal cells. Finally, we demonstrate the combined added benefits of selective stimulation of ERß, including the induction of cell death in quiescent post-castration tissues. Subsequent to castration ERß-induces further apoptosis in basal, luminal and intermediate cells. Our results reveal a novel benefit of ERß activation for prostate disease and suggest that combining selective activation of ERß with androgen-deprivation may be a feasible strategy to target stem cells implicated in the origin of prostatic disease.

Aromatase and regulating the estrogen:androgen ratio in the prostate gland.

Although androgens and estrogens both play significant roles in the prostate, it is their combined action--and specifically their balance--that is critically important in maintaining prostate health and tissue homeostasis in adulthood. In men, serum testosterone levels drop by about 35% between the ages of 21 and 85 while estradiol levels remain constant or increase. This changing androgen:estrogen (T:E) ratio has been implicated in the development of benign and malignant prostate disease. The production of estrogens from androgens is mediated by the aromatase enzyme, the aberrant expression of which plays a critical role in the development of malignancy in a number of tissues. The normal prostate expresses aromatase within the stroma, while there is an induction of epithelial expression in malignancy with altered promoter utilisation. This may ultimately lead to an altered T:E ratio that is associated with the development of disease. The role of estrogen and the T:E balance in the prostate is further complicated by the differential actions of both estrogen receptors, alpha and beta. Stimulation of ERalpha leads to aberrant proliferation, inflammation and pre-malignant pathology; whereas activation of ERbeta appears to have beneficial effects regarding cellular proliferation and a putative protective role against carcinogenesis. Overall, these data reveal that homeostasis in the normal prostate involves a finely tuned balance between androgens and estrogens. This has identified estrogen, in addition to androgens, as integral to maintaining normal prostate health, but also as an important mediator of prostate disease.

The dual, opposing roles of estrogen in the prostate.

Both androgens and estrogens play a significant role in the prostate and are critical for normal prostate growth and development. The role of androgens in the prostate and in prostate disease is well known, however, the role for estrogens in the prostate and in prostate disease is complex and is still only just beginning to be appreciated. Our understanding of the role and action of estrogens in the prostate has advanced significantly recently due to important discoveries, including the discovery of a second estrogen receptor subtype (ER-beta), the detection of aromatase in the prostate, and the identification of rapid nongenomic estrogen signaling. We now know that estrogens are essential for normal tissue homeostasis within the prostate and that too little or too much leads to perturbation of the glands growth and the emergence of disease. We are also beginning to recognize the importance and differential roles of the estrogen receptors ER-alpha and ER-beta. Specifically, the activation of ER-alpha leads to aberrant proliferation, inflammation, and the development of premalignant lesions, while, in contrast, the activation of ER-beta is critical in prostatic stromal-epithelial cell signaling and mediating antiproliferative effects that balance the proliferative action of androgens on the epithelia. These data have established the importance and complexity of estrogen action. We now know that estrogens have the capacity to exert both beneficial and adverse effects in the prostate via ER-beta and ER-alpha, respectively. Based on this, the selective targeting of estrogen action may form the basis of new therapies for prostate disease.

Estrogen action on the prostate gland: a critical mix of endocrine and paracrine signaling.

Although modern biotechnology has provided us with a greater understanding of the molecular events in endocrine-related diseases, such as benign prostatic hyperplasia and prostate cancer, these conditions continue to be a significant healthcare problem world-wide. As the number of men afflicted by these diseases will only continue to grow with the aging population, finding new strategies and new therapeutic options for the treatment of both of these diseases is crucial. A better knowledge of the mechanisms of hormone action is pivotal to making progress in the development of new hormone-based therapies. This is fundamental to increasing our understanding of the endocrine, paracrine, and autocrine signaling mechanisms in the prostate and in prostate disease, distinguishing the effects and role of each, and identifying where and how this communication goes wrong.