Evidence that epithelial and mesenchymal estrogen receptor-alpha mediates effects of estrogen on prostatic epithelium

The Role of ERα and ERβ in Castration-Resistant Prostate Cancer and Current Therapeutic Approaches

Castration-resistant prostate cancer, or CRPC, is an aggressive stage of prostate cancer (PCa) in which PCa cells invade nearby or other parts of the body. When a patient with PCa goes through androgen deprivation therapy (ADT) and the cancer comes back or worsens, this is called CRPC. Instead of androgen-dependent signalling, recent studies show the involvement of the estrogen pathway through the regulation of estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ) in CRPC development. Reduced levels of testosterone due to ADT lead to low ERβ functionality in inhibiting the proliferation of PCa cells. Additionally, ERα, which possesses androgen independence, continues to promote the proliferation of PCa cells. The functions of ERα and ERβ in controlling PCa progression have been studied, but further research is needed to elucidate their roles in promoting CRPC. Finding new ways to treat the disease and stop it from becoming worse will require a clear understanding of the molecular processes that can lead to CRPC. The current review summarizes the underlying processes involving ERα and ERβ in developing CRPC, including castration-resistant mechanisms after ADT and available medication modification in mitigating CRPC progression, with the goal of directing future research and treatment.

Prognostic value of estrogen receptors in patients who underwent prostatectomy for non‑metastatic prostate cancer

Estrogen receptors in prostate cancer (PCa) are a subject of debate. The aim of the present study was to investigate whether estrogen receptor-α (ERα) and estrogen receptor-β (ERβ) impact the biochemical recurrence (BCR) of non-metastatic PCa after surgery. Following the application of the exclusion criteria, data from 108 patients who underwent laparoscopic radical prostatectomy between January 2011 and December 2019 were retrospectively evaluated. A total of 36 patients with BCR constituted the BCR group. The control group was formed using the Propensity Score Matching (PSM) method with a 1:2 ratio, including parameters with well-studied effects on BCR. The median follow-up time was 74.3 (range, 30-127.5) months in the BCR group and 66.6 (range, 31.5-130) months in the control group. Pathology specimens from the two groups were immunohistochemically stained with ERα and ERβ antibodies. Logistic regression analysis and survival analysis were performed. No differences in clinicopathological characteristics were detected between the two groups. The patients with ERα(-)/ERβ(+) staining results had a significantly fewer BCRs than other patients (P=0.024). In the logistic regression analysis, patients with ERα(-)/ERβ(+) PCa also had a significantly lower risk of recurrence (P=0.048). In the survival analysis, the 5-year BCR-free survival rate of patients with ERα(-)/ERβ(+) PCa was higher than that of other patients (85.7 vs. 66.1%; P=0.031). Excluding the effects of well-studied risk factors for recurrence by the PSM method, the present study showed that ERα and ERβ have prognostic value for non-metastatic PCa. The 5-year BCR-free survival rate is significantly higher in patients whose PCa tissue has ERα(-)/ERβ(+) staining results.

Semen quality, testosterone values, and testicular and accessory gland parameters in rams receiving sustained stimulation with low doses of buserelin

ContextThe use of buserelin, a gonadotropin-releasing hormone (GnRH) agonist, can improve semen quality. Nevertheless, the appropriate dosage, and frequency and time of application, remain to be established owing to the subsequent negative feedback on endogenous production of testosterone described so far.AimsThis study aimed to propose a new buserelin application protocol for sperm improvement in Santa Inês rams.MethodsFifteen Santa Inês rams were divided into two experimental groups: the first group (n=8) received 2.5μg buserelin acetate; and the second group (n=7) received saline solution. Treatments were applied for 21 days at intervals of 6h, totalling four hormonal or saline applications per day. In all animals, macroscopic and microscopic seminal characteristics and freezability, plasma testosterone, pixels of testicular parenchyma, and biometric analysis of testicular and accessory sex glands by ultrasound were evaluated throughout the period of hormonal application and for a further 7 days.Key resultsRams receiving buserelin showed a peak of testosterone after the first week (Day 7) of application, with a drop in values at Day 14, followed by negative feedback at Day 21 and return to basal concentrations at Day 28. They also showed improvement of kinetics parameters such as straight line velocity (μm/s: +buserelin 51.5±1.5 > control 46.6±1.6) and linearity coefficient (%: +buserelin 53.5±1.8 > control 47.5±1.9). Ultrasound parameters, pixels of testicular parenchyma, and freezability were not affected by treatment.ConclusionsThe administration of buserelin was able to improve some sperm kinetics parameters of Santa Inês rams.ImplicationsLow doses of this GnRH analogue can be used; however, further adjustments to the hormonal protocol are needed to obtain an effective improvement in sperm quality.

Estrogen Receptor ß in Cancer: To ß(e) or not to ß(e)?

Estrogen receptors (ERs) are known to play an important role in the proper development of estrogen-sensitive organs, as well as in the development and progression of various types of cancer. ERα, the first ER to be discovered, has been the focus of most cancer research, especially in the context of breast cancer. However, ERβ expression also plays a significant role in cancer pathophysiology, notably its seemingly protective nature and loss of expression with oncogenesis and progression. Although ERβ exhibits antitumor activity in breast, ovarian, and prostate cancer, its expression is associated with disease progression and worse prognosis in lung cancer. The function of ERβ is complicated by the presence of multiple isoforms and single nucleotide polymorphisms, in addition to tissue-specific functions. This mini-review explores current literature on ERβ and its mechanism of action and clinical implications in breast, ovarian, prostate, and lung cancer.

Combined Effects of Different Endocrine-Disrupting Chemicals (EDCs) on Prostate Gland

Endocrine-disrupting chemicals (EDCs) belong to a heterogeneous class of environmental pollutants widely diffused in different aquatic and terrestrial habitats. This implies that humans and animals are continuously exposed to EDCs from different matrices and sources. Moreover, pollution derived from anthropic and industrial activities leads to combined exposure to substances with multiple mechanisms of action on the endocrine system and correlated cell and tissue targets. For this reason, specific organs, such as the prostate gland, which physiologically are under the control of hormones like androgens and estrogens, are particularly sensitive to EDC stimulation. It is now well known that an imbalance in hormonal regulation can cause the onset of various prostate diseases, from benign prostate hyperplasia to prostate cancer. In this review, starting with the description of normal prostate gland anatomy and embryology, we summarize recent studies reporting on how the multiple and simultaneous exposure to estrogenic and anti-androgenic compounds belonging to EDCs are responsible for an increase in prostate disease incidence in the human population.

Estrogens and development of the rete testis, efferent ductules, epididymis and vas deferens

Estrogen has always been considered the female hormone and testosterone the male hormone. However, estrogen's presence in the testis and deleterious effects of estrogen treatment during development have been known for nearly 90 years, long before estrogen receptors (ESRs) were discovered. Eventually it was learned that testes actually synthesize high levels of estradiol (E2) and sequester high concentrations in the reproductive tract lumen, which seems contradictory to the overwhelming number of studies showing reproductive pathology following exogenous estrogen exposures. For too long, the developmental pathology of estrogen has dominated our thinking, even resulting in the "estrogen hypothesis" as related to the testicular dysgenesis syndrome. However, these early studies and the development of an Esr1 knockout mouse led to a deluge of research into estrogen's potential role in and disruption of development and function of the male reproductive system. What is new is that estrogen action in the male cannot be divorced from that of androgen. This paper presents what is known about components of the estrogen pathway, including its synthesis and target receptors, and the need to achieve a balance between androgen- and estrogen-action in male reproductive tract differentiation and adult functions. The review focuses on what is known regarding development of the male reproductive tract, from the rete testis to the vas deferens, and examines the expression of estrogen receptors and presence of aromatase in the male reproductive system, traces the evidence provided by estrogen-associated knockout and transgenic animal models and discusses the effects of fetal and postnatal exposures to estrogens. Hopefully, there will be enough here to stimulate discussions and new investigations of the androgen:estrogen balance that seems to be essential for development of the male reproductive tract.

Ontogeny of estrogen receptors in human male and female fetal reproductive tracts

This paper reviews and provides new observations on the ontogeny of estrogen receptor alpha (ESR1) and estrogen receptor beta (ESR2) in developing human male and female internal and external genitalia. Included in this study are observations on the human fetal uterine tube, the uterotubal junction, uterus, cervix, vagina, penis and clitoris. We also summarize and report on the ontogeny of estrogen receptors in the human fetal prostate, prostatic urethra and epididymis. The ontogeny of ESR1 and ESR2, which spans from 8 to 21 weeks correlates well with the known "window of susceptibility" (7-15 weeks) for diethylstilbestrol (DES)-induced malformations of the human female reproductive tract as determined through examination of DES daughters exposed in utero to this potent estrogen. Our fairly complete mapping of the ontogeny of ESR1 and ESR2 in developing human male and female internal and external genitalia provides a mechanistic framework for further investigation of the role of estrogen in normal development and of abnormalities elicited by exogenous estrogens.

Oral exposure to low-dose bisphenol A induces hyperplasia of dorsolateral prostate and upregulates EGFR expression in adult Sprague-Dawley rats

Prostate is sensitive to endocrine hormone level, and the synergetic effect of estrogen and androgen is critical in prostate growth. The change of signal pathways caused by the imbalance of estrogen and androgen might function in the occurrence of prostate diseases. As a well-known endocrine disruptor compound, bisphenol A (BPA) can disturb the normal function of endocrine hormone and affect prostate development. This study aims to investigate effects of BPA on the dorsolateral prostate (DLP) and the related gene expression of the tissue in adult Sprague-Dawley (SD) rats and to explore the mechanism for the effect of low-dose BPA on DLP hyperplasia. Three-month-old male SD rats were treated with BPA (10.0, 30.0, or 90.0 µg (kg.day)^-1, gavage) or vehicle (gavage) for 4 weeks. BPA significantly increased the DLP weight, the DLP organ coefficient, and the prostate epithelium height (p < 0.01) of rats dose-dependently. Microarray analysis and quantitative real-time polymerase chain reaction showed that BPA significantly upregulated the transcriptional levels of some genes, including pituitary tumor transforming gene 1, epidermal growth factor, Sh3kbp1, and Pcna. Furthermore, the expression of PCNA (p < 0.01), androgen receptor (p < 0.01), and EGF receptor (EGFR) (p < 0.001) in DLP was increased significantly by BPA treatment, and the expression of estrogen receptor alpha was also upregulated. The findings evidenced that low-dose BPA could induce DLP hyperplasia in adult rats, and the upregulated EGF/EGFR pathway that was responsive to estrogen and androgen might play an essential role in the DLP hyperplasia induced by low-dose BPA.

Genome-Wide Analysis of Low Dose Bisphenol-A (BPA) Exposure in Human Prostate Cells

Endocrine disrupting compounds (EDCs) have the potential to cause adverse effects on wild-life and human health. Two important EDCs are the synthetic estrogen 17α-ethynylestradiol (EE2) and bisphenol-A (BPA) both of which are xenoestrogens (XEs) as they bind the estrogen receptor and dis-rupt estrogen physiology in mammals and other vertebrates. In the recent years the influence of XEs on oncogenes, specifically in relation to breast and prostate cancer has been the subject of considerable study.

Estrogen in the male: a historical perspective

Estrogens have traditionally been considered female hormones. Nevertheless, the presence of estrogen in males has been known for over 90 years. Initial studies suggested that estrogen was deleterious to male reproduction because exogenous treatments induced developmental abnormalities. However, demonstrations of estrogen synthesis in the testis and high concentrations of 17β-estradiol in rete testis fluid suggested that the female hormone might have a function in normal male reproduction. Identification of estrogen receptors and development of biological radioisotope methods to assess estradiol binding revealed that the male reproductive tract expresses estrogen receptor extensively from the neonatal period to adulthood. This indicated a role for estrogens in normal development, especially in efferent ductules, whose epithelium is the first in the male reproductive tract to express estrogen receptor during development and a site of exceedingly high expression. In the 1990s, a paradigm shift occurred in our understanding of estrogen function in the male, ushered in by knockout mouse models where estrogen production or expression of its receptors was not present. These knockout animals revealed that estrogen's main receptor (estrogen receptor 1 [ESR1]) is essential for male fertility and development of efferent ductules, epididymis, and prostate, and that loss of only the membrane fraction of ESR1 was sufficient to induce extensive male reproductive abnormalities and infertility. This review provides perspectives on the major discoveries and developments that led to our current knowledge of estrogen's importance in the male reproductive tract and shaped our evolving concept of estrogen's physiological role in the male.

Biochemical Effects of Oleuropein in Streptozotocin Induced Diabetic Male Rat

Diabetes is a chronic disease characterized by a disorder in the metabolism of proteins, fats, and carbohydrates. The liver as a non-insulin dependent organ plays an important role in the regulation of blood fat and glucose. Most blood glucose lowering drugs that are introduced for treatment have side effects in long-term consumption. Therefore, to control diabetes and its complications, the use of herbal drugs is widely considered nowadays. The present study investigates the biochemical effects of oleuropein in diabetic male rats. In this study, 30 adult male Wistar rats with a weight range of 190±30 gr were equally divided into 3 groups randomly: 1) control group or intact animals, 2) diabetic animals, and 3) treatment group, which received 60 mg/kg oleuropein for 30 days by gastric gavage. Diabetes was induced in diabetic and treatment groups by injection of streptozotocin (60 mg/kg) intraperitoneally. At the end of the treatment, the levels of triglyceride, cholesterol, LDL, HDL, VLDL, blood glucose, HbA1C, and activity of AST and ALT were determined. The results showed that the serum lipid profile and blood glucose increased significantly in the diabetic group compared with the control group (p<0.05). Also, HbA1C and atherogenic index decreased significantly in the treatment group compared with the diabetic group (p<0.05). This study showed that oral administration of oleuropein has hypoglycemic effects, which can reduce the serum levels of the lipids profile and the atherogenic index in streptozotocin-induced diabetic male rats.

Role of Stromal Paracrine Signals in Proliferative Diseases of the Aging Human Prostate

Androgens are essential for the development, differentiation, growth, and function of the prostate through epithelial–stromal interactions. However, androgen concentrations in the hypertrophic human prostate decrease significantly with age, suggesting an inverse correlation between androgen levels and proliferative diseases of the aging prostate. In elderly males, age- and/or androgen-related stromal remodeling is spontaneously induced, i.e., increased fibroblast and myofibroblast numbers, but decreased smooth muscle cell numbers in the prostatic stroma. These fibroblasts produce not only growth factors, cytokines, and extracellular matrix proteins, but also microRNAs as stromal paracrine signals that stimulate prostate epithelial cell proliferation. Surgical or chemical castration is the standard systemic therapy for patients with advanced prostate cancer. Androgen deprivation therapy induces temporary remission, but the majority of patients eventually progress to castration-resistant prostate cancer, which is associated with a high mortality rate. Androgen deprivation therapy-induced stromal remodeling may be involved in the development and progression of castration-resistant prostate cancer. In the tumor microenvironment, activated fibroblasts stimulating prostate cancer cell proliferation are called carcinoma-associated fibroblasts. In this review, we summarize the role of stromal paracrine signals in proliferative diseases of the aging human prostate and discuss the potential clinical applications of carcinoma-associated fibroblast-derived exosomal microRNAs as promising biomarkers.

Basal Cells Show Increased Expression of Aromatase and Estrogen Receptor α in Prostate Epithelial Lesions of Male Aging Rats

Besides androgens, estrogen signaling plays a key role in normal development and pathologies of the prostate. Irreversible synthesis of estrogens from androgens is catalyzed by aromatase. Interestingly, animals lacking aromatase do not develop cancer or prostatitis, whereas those with overexpression of aromatase and, consequently, high estrogen levels develop prostatitis and squamous metaplasia via estrogen receptor 1 (ERα). Even with this evidence, the aromatase expression in the prostate is controversial. Moreover, little is known about the occurrence of age-dependent variation of aromatase and its association with histopathological changes commonly found in advanced age, a knowledge gap that is addressed herein. For this purpose, the immunoexpression of aromatase was evaluated in the prostatic complex of young adult to senile Wistar rats. ERα was also investigated, to extend our understanding of estrogen responsiveness in the prostate. Moderate cytoplasmic immunoreactivity for aromatase was detected in the glandular epithelium. Eventually, some basal cells showed intense staining for aromatase. The expression pattern for aromatase appeared similar in the normal epithelium when young and senile rats were compared; this result was corroborated by Western blotting. Conversely, in senile rats, there was an increase in the frequency of basal cells intensely stained for aromatase, which appeared concentrated in areas of intraepithelial proliferation and prostatitis. These punctual areas also presented increased ERα positivity. Together, these findings suggest a plausible source for hormonal imbalance favoring estrogen production, which, by acting through ERα, may favor the development of prostatic lesions commonly found in advanced age.

Prostate cancer xenografts and hormone induced prostate carcinogenesis

Despite the advancement of transgenic and gene knockout animal models in the prostate cancer research, there is still a need for utilizing xenograft models. Xenografts can be grown in multiple sites/organs within immunocompromised animals such as mice and rats. Although prostate xenografts have been derived from many species, human cells and tissues are the most commonly used due to their potential clinical significance. Xenograft models that progress from one state or stage to another are commonly used to address important scientific questions including malignant transformation, metastatic spread, and castration resistance. Utilization of xenografts are commonly being used to assess the biology and genetics of prostate cancer, as well as, for therapeutic benefit. In addition to models for the study of prostate cancer, xenografts are also utilized as a tool in precision medicine where patient derived xenografts (PDX) can be grown in multiple animals and assessed for therapeutic efficacy. The popularity of such xenograft models and PDXs have led to availability of these resources through public and commercial institutions. In this review, we describe both traditional and emerging models of prostate cancer and their potential uses. Further development of current models and introduction of new models will likely provide new insights and better understanding of prostatic carcinogenesis and progression.

Estrogens in Male Physiology

Estrogens have historically been associated with female reproduction, but work over the last two decades established that estrogens and their main nuclear receptors (ESR1 and ESR2) and G protein-coupled estrogen receptor (GPER) also regulate male reproductive and nonreproductive organs. 17β-Estradiol (E2) is measureable in blood of men and males of other species, but in rete testis fluids, E2 reaches concentrations normally found only in females and in some species nanomolar concentrations of estrone sulfate are found in semen. Aromatase, which converts androgens to estrogens, is expressed in Leydig cells, seminiferous epithelium, and other male organs. Early studies showed E2 binding in numerous male tissues, and ESR1 and ESR2 each show unique distributions and actions in males. Exogenous estrogen treatment produced male reproductive pathologies in laboratory animals and men, especially during development, and studies with transgenic mice with compromised estrogen signaling demonstrated an E2 role in normal male physiology. Efferent ductules and epididymal functions are dependent on estrogen signaling through ESR1, whose loss impaired ion transport and water reabsorption, resulting in abnormal sperm. Loss of ESR1 or aromatase also produces effects on nonreproductive targets such as brain, adipose, skeletal muscle, bone, cardiovascular, and immune tissues. Expression of GPER is extensive in male tracts, suggesting a possible role for E2 signaling through this receptor in male reproduction. Recent evidence also indicates that membrane ESR1 has critical roles in male reproduction. Thus estrogens are important physiological regulators in males, and future studies may reveal additional roles for estrogen signaling in various target tissues.

Immunohistochemical analysis of estrogen receptors in prostate and clinical correlation in men with benign prostatic hyperplasia

Purpose

Estrogens act through interaction with 2 receptor subtypes, ER alpha (ERα) and ER beta (ERβ), in human prostate. The aim of the present study was to semiquantitatively assess the differential expression of ER subtypes in human benign prostatic hyperplasia (BPH) by use of immunocytochemistry (IHC) methods and to explore their relationship with various measures of BPH.

Materials and Methods

A total of 45 patients with BPH undergoing transurethral resection of the prostate and 22 patients with bladder cancer with normal prostate undergoing surveillance cystoscopy were studied as cases and controls, respectively. Quantitative immunolabeling of ER subtypes was scored by use of a semiquantitative scale. Also, correlations were assessed between ER levels in prostate and various measures of BPH.

Results

Overall, we found strong immunostaining for ERα in stroma and for ERβ in epithelium, respectively. The IHC score for ERα differed significantly between BPH patients and controls in both stroma (p≤0.001) and epithelium (p=0.008), respectively. The ERβ IHC score was also significantly higher in the epithelium of BPH patients (p=0.01). Also, we found a significant correlation between prostatic ER levels and various clinical measures of BPH.

Conclusions

ERs may play an important role in the pathogenesis of BPH.

Steroid Hormone Receptors as Potential Mediators of the Clinical Effects of Dutasteride: A Prospective, Randomized, Double-Blind Study

This study characterizes the clinical and morphofunctional effects of a 5α-reductase inhibitor on steroid hormone receptors in normal human prostate tissue, as potential mediators of the clinical effects of dutasteride. This work was a prospective, double-blind, and randomized study that evaluated 49 men aged between 45 and 70 years, with no alterations in a digital rectal examination and prostate-specific antigen measurements between 2.5 and 4.0 ng/mL. These patients underwent prostate biopsy guided by transretal ultrasound with prostate neoplasia being ruled out, and the patients were divided into two groups, with one group receiving dutasteride ( n = 25) and one group receiving a placebo ( n = 24). The patients were clinically assessed each quarter, and at the end of 12 months they underwent new laboratory tests, prostate rebiopsy, and histopathological, immunohistochemical and clinical analyses. The estrogen receptor-beta (ERβ) and androgen receptor immunoreactivities were higher, and the proliferation/apoptotic ratio was significantly lower with predominance of the apoptotic process, followed by a significant reduction in the prostate volume and the total serum prostate-specific antigen levels in the dutasteride group when compared with the placebo group, with a clear supremacy of ERβ. There were no significant variations in the serum estrogen and testosterone levels, in the body mass index, or in the ERα immunoreactivities in the dutasteride and placebo groups. The results demonstrated the importance of the ERβ pathway in the activation mechanisms of apoptosis, exerting a protective effect in the normal prostate, indicating that this receptor might be an important mediator of the clinical effects of dutasteride.

Gestational and lactational exposition to Di-N-butyl-phthalate (DBP) increases inflammation and preneoplastic lesions in prostate of wistar rats after carcinogenic N-methyl-N-nitrosourea (MNU) plus testosterone protocol

In the present study, it was evaluated the susceptibility of prostatic lesions in male adult rats exposed to Di-N-butyl-phthalate during fetal and lactational periods and submitted to MNU plus testosterone carcinogenesis protocol. Pregnant females were distributed into four experimental groups: CN (negative control); CMNU (MNU control); TDBP100 (100 mg/kg of DBP); TDBP500 (500 mg/kg of DBP). Females from the TDBP groups received DBP, by gavage, from gestation day 15 (GD15) to postnatal day 21 (DPN21), while C animals received the vehicle (corn oil). CMNU, TDBP100, and TDBP500 groups received a single intraperitoneal injection of MNU (50 mg/kg) on the sixth postnatal week. After that, testosterone cypionate was administered subcutaneously two times a week (2 mg/kg) for 24 weeks. The animals were euthanized on PND220. Distal segment fragments of the ventral (VP) and dorsolateral prostate (DLP) were fixed and processed for histopathological analysis. Protein extracts from ventral prostate were obtained, and western blotting was performed to AR, ERα, MAPK (ERK1/2), and pan-AKT. Stereological analysis showed an increase in the epithelial compartment in TDBP100 and TDBP500 compared to CN. In general, there was increase in the incidence of inflammation and metaplasia/dysplasia in the DBP-treated groups, mainly in DLP, compared to CN and CMNU. Proliferation index was significant higher in TDBP500 and PIN (prostatic intraepithelial neoplasia) was more frequent in this group compared to CMNU. Western blot assays showed an increase in the expressions of AR and MAPK (ERK1/2) in the TDBP100 compared to CN, and ERα and AKT expressions were higher in the TDBP500 group compared do CN. These results showed that different doses of DBP during prostate organogenesis in Wistar rats could increase the incidence of premalignant lesions in initiated rats inducing distinct biological responses in the adulthood. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1185-1195, 2016.

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.

Enhancing active surveillance of prostate cancer: the potential of exercise medicine

Active surveillance (AS) is a strategy for the management of patients with low-risk, localized prostate cancer, in which men undergo regular monitoring of serum PSA levels and tumour characteristics, using multiparametric MRI and repeat biopsy sampling, to identify signs of disease progression. This strategy reduces overtreatment of clinically insignificant disease while also preserving opportunities for curative therapy in patients whose disease progresses. Preliminary studies of lifestyle interventions involving basic exercise advice have indicated that exercise reduces the numbers of patients undergoing active treatment, as well as modulating the biological processes involved in tumour progression. Therefore, preliminary evidence suggests that lifestyle and/or exercise interventions might have therapeutic potential in this growing population of men with prostate cancer. However, several important issues remain unclear: the exact value of different types of lifestyle and exercise medicine interventions during AS; the biological mechanisms of exercise in delaying disease progression; and the influence of the anxieties and distress created by having a diagnosis of cancer without then receiving active treatment. Future studies are required to confirm and expand these findings and determine the relative contributions of each lifestyle component to specific end points and patient outcomes during AS.

Loss of ATF3 promotes hormone-induced prostate carcinogenesis and the emergence of CK5(+)CK8(+) epithelial cells

Steroid sex hormones can induce prostate carcinogenesis, and are thought to contribute to the development of prostate cancer during aging. However, the mechanism for hormone-induced prostate carcinogenesis remains elusive. Here we report that activating transcription factor 3 (ATF3) – a broad stress sensor – suppressed hormone-induced prostate carcinogenesis in mice. While implantation of testosterone and estradiol (T+E₂) pellets for 2 months in wild-type mice rarely induced prostatic intraepithelial neoplasia (PIN) in dorsal prostates (1 out of 8 mice), loss of ATF3 led to the appearance of not only PIN but also invasive lesions in almost all examined animals. The enhanced carcinogenic effects of hormones on ATF3-deficient prostates did not appear to be caused by a change in estrogen signaling, but were more likely a consequence of elevated androgen signaling that stimulated differentiation of prostatic basal cells into transformation-preferable luminal cells. Indeed, we found that hormone-induced lesions in ATF3-knockout mice often contained cells with both basal and luminal characteristics, such as p63⁺ cells (a basal cell marker) showing luminal-like morphology, or cells double-stained with basal (CK5⁺) and luminal (CK8⁺) markers. Consistent with these findings, low ATF3 expression was found to be a poor prognostic marker for prostate cancer in a cohort of 245 patients. Our results thus support that ATF3 is a tumor suppressor in prostate cancer.

Associations between estrogen receptor genetic polymorphisms, smoking status, and prostate cancer risk: a case-control study in Japanese men

OBJECTIVE

Prostate cancer (PCa) is one of the major causes of death among men. Our study investigated the association of ESR1 and ESR2 genotypes with susceptibility to PCa in relation to smoking status in Japanese.

METHOD

A case-control study was performed with 750 Japanese prostate cancer patients and 870 healthy controls. After age-matching in case-controls, 352 controls and 352 cases were enrolled in this study. By using logistic regression analysis, the different genotypes from ESR1 and ESR2 were analyzed according to case/control status.

RESULT

ESR2 rs4986938 AG and AG + AA genotypes were associated with significantly decreased risk of PCa (AG: OR = 0.68, 95 % CI 0.47-0.97, P < 0.05 and AG + AA: OR = 0.67, 95 % CI 0.47-0.94, P < 0.05). However, there was no significant association between ESR1 rs2234693 and PCa risk. When patients were grouped according to smoking status, the ESR2 rs1256049 AA genotype (OR = 0.48, 95 % CI 0.25-0.95, P < 0.05) and ESR2 rs4986938 AG + AA genotype (OR = 0.64, 95 % CI 0.41-1.00, P < 0.05) showed significantly decreased PCa risk in the ever-smoker group.

CONCLUSION

Our results suggest that the estrogen receptor ESR2 has a very important function to predict PCa and that different SNPs have different predictive values. Smoking may influence estrogenic activity and may influence PCa together with the estrogen receptor.

Differential expression and regulation of vitamin D hydroxylases and inflammatory genes in prostate stroma and epithelium by 1,25-dihydroxyvitamin D in men with prostate cancer and an in vitro model

Previous work on vitamin D in the prostate has focused on the prostatic epithelium, from which prostate cancer arises. Prostatic epithelial cells are surrounded by stroma, which has well-established regulatory control over epithelial proliferation, differentiation, and the inflammatory response. Here we examined the regulation of vitamin D-related genes and inflammatory genes by 1α,25-dihydroxyvitamin D3 (1,25(OH)2D) in laser-capture microdissected prostate tissue from a vitamin D3 clinical trial and in an in vitro model that facilitates stromal-epithelial crosstalk. Analysis of the trial tissues showed that VDR was present in both cell types, whereas expression of the hydroxylases was the highest in the epithelium. Examination of gene expression by prostatic (1,25(OH)2D) concentrations showed that VDR was significantly lower in prostate tissues with the highest concentration of 1,25(OH)2D, and down-regulation of VDR by 1,25(OH) 2D was confirmed in the primary cell cultures. Analysis of inflammatory genes in the patient tissues revealed that IL-6 expression was the highest in the prostate stroma while PTGS2 (COX2) levels were lowest in the prostate cancer tissues from men in the highest tertile of prostatic 1,25(OH)2D. In vitro, TNF-α, IL-6 and IL-8 were suppressed by 1,25 (OH)2D in the primary epithelial cells, whereas TNF-α and PTGS2 were suppressed by 1,25(OH) 2D in the stromal cells. Importantly, the ability of 1,25(OH)2D to alter pro-inflammatory-induced changes in epithelial cell growth were dependent on the presence of the stromal cells. In summary, whereas both stromal and epithelial cells of the prostate express VDR and can presumably respond to 1,25(OH)2D, the prostatic epithelium appears to be the main producer of 1,25(OH)2D. Further, while the prostate epithelium was more responsive to the anti-inflammatory activity of 1,25 (OH)2D than stromal cells, stroma-epithelial crosstalk enhanced the phenotypic effects of 1,25(OH)2D and the inflammatory process in the prostate gland.

Clinical significance of estrogen receptor β in breast and prostate cancer from biological aspects

Breast and prostate cancers are among the most common of all cancers. They are referred to as hormone-dependent cancers, because estrogen and androgen are involved in their development and growth. The effects of these hormones are mediated by their respective receptors, estrogen receptor (ER) α and androgen receptor. Around 18 years ago, a second ER, ERβ, which has a very similar structure to ERα, was discovered. Its function has been investigated using a variety of methods and biological systems, leading to our present understanding that ERβ can interact with or inhibit ERα and androgen receptor function directly and/or indirectly, suppress cell growth, and influence responsiveness to endocrine therapy. In order to apply the “inhibition of cell growth” function to cancer treatment, several specific ERβ agonists have been synthesized and are being tested for effectiveness in cancer treatment. We need to keep our eyes on ERβ.

Estrogen receptor-α is a key mediator and therapeutic target for bladder complications of benign prostatic hyperplasia

PURPOSE

Estrogens are important in prostate growth and have a role in benign prostatic hyperplasia. However, to our knowledge no current therapy directly targets estrogen action. Estrogens act primarily via estrogen receptors α and β. In a mouse model we evaluated the relative contribution of these receptors to bladder complications of benign prostatic hyperplasia. We also evaluated the prevention of these bladder complications using the selective estrogen receptor modulators raloxifene and tamoxifen (estrogen receptor-α selective antagonists), and R,R-THC (estrogen receptor-β selective antagonist).

MATERIALS AND METHODS

Adult male C57bl/6 mice received implants of 25 mg testosterone and 2.5 mg 17β-estradiol slow release pellets. Untreated controls underwent sham surgery. We evaluated the contributions of the estrogen receptor subtypes in ERαKO and ERβKO mice compared to their respective wild-type litter mates. Wild-type mice treated with testosterone plus 17β-estradiol were compared to mice treated with testosterone plus 17β-estradiol and 25 mg selective estrogen receptor modulators to evaluate the prevention of benign prostatic hyperplasia complications by selective estrogen receptor modulators.

RESULTS

Large bladders with urinary retention developed in ERαWT and ERβWT litter mates treated with testosterone plus 17β-estradiol but such bladders did not develop in ERαKO mice treated with testosterone plus 17β-estradiol. ERβKO mice treated with testosterone plus 17β-estradiol had large bladders with urinary retention and increased bladder mass. Cotreatment with the estrogen receptor-α antagonist raloxifene resulted in decreased bladder mass compared to that in wild-type mice treated with testosterone plus 17β-estradiol. Bladders in mice treated with the estrogen receptor-β antagonist R,R-THC were similar to those in testosterone plus 17β-estradiol treated mice.

CONCLUSIONS

Estrogen receptor-α but not β is a key mediator of bladder complications of benign prostatic hyperplasia and a potential target for future therapies.

Deficiency of ERβ and prostate tumorigenesis in FGF8b transgenic mice

Estrogens contribute to the development and growth of the prostate and are implicated in prostate tumorigenesis. In their target tissues, estrogens mediate their effects via estrogen receptor α (ERα (ESR1)) and β (ERβ (ESR2)). Hyperplasia and decreased differentiation of epithelial cells in the prostate have been reported in ERβ knockout (BERKO) mice. Herein, we studied the effect of ERβ deficiency on prostate tumorigenesis by crossing BERKOFVB mice with prostate-targeted human fibroblast growth factor 8b transgenic (FGF8b-Tg) mice. Consistent with results described in our previous report, the prostates of 1-year-old FGF8b-Tg mice displayed stromal aberrations, prostatic intraepithelial neoplasia (mPIN) lesions, inflammation, and occasionally cancer. The prostates of BERKOFVB mice exhibited mild epithelial hypercellularity and inflammation. The prostate phenotypes of FGF8b-Tg-BERKOFVB mice closely resembled those of FGF8b-Tg mice. However, mucinous metaplasia, indicated by Goblet-like cells in the epithelium, was significantly more frequent in the prostates of FGF8b-Tg-BERKOFVB mice when compared with FGF8b-Tg mice. Furthermore, compared with FGF8b-Tg mice, there was a tendency for increased frequency of inflammation but milder hyperplasias in the prostate stroma of FGF8b-Tg-BERKOFVB mice. The expression levels of mRNAs for FGF8b-regulated genes including osteopontin (Spp1), connective tissue growth factor (Ctgf), fibroblast growth factor receptors (Fgfrs), and steroid hormone receptors and cytokines were similar in the prostates of FGF8b-Tg and FGF8b-Tg-BERKOFVB mice. Our results indicate that ERβ plays a role in the differentiation of the prostatic epithelium and, potentially, in the defensive mechanism required for protection against inflammation but do not support a direct tumor-suppressive function of ERβ in the prostate of FGF8b-Tg mice.

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 ERβ, 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 ERβ 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.

Expression of androgen and estrogen signaling components and stem cell markers to predict cancer progression and cancer-specific survival in patients with metastatic prostate cancer

PURPOSE

Genes of androgen and estrogen signaling cells and stem cell-like cells play crucial roles in prostate cancer. This study aimed to predict clinical failure by identifying these prostate cancer-related genes.

EXPERIMENTAL DESIGN

We developed models to predict clinical failure using biopsy samples from a training set of 46 and an independent validation set of 30 patients with treatment-naïve prostate cancer with bone metastasis. Cancerous and stromal tissues were separately collected by laser-captured microdissection. We analyzed the association between clinical failure and mRNA expression of the following genes androgen receptor (AR) and its related genes (APP, FOX family, TRIM 36, Oct1, and ACSL 3), stem cell-like molecules (Klf4, c-Myc, Oct 3/4, and Sox2), estrogen receptor (ER), Her2, PSA, and CRP.

RESULTS

Logistic analyses to predict prostate-specific antigen (PSA) recurrence showed an area under the curve (AUC) of 1.0 in both sets for Sox2, Her2, and CRP expression in cancer cells, AR and ERα expression in stromal cells, and clinical parameters. We identified 10 prognostic factors for cancer-specific survival (CSS): Oct1, TRIM36, Sox2, and c-Myc expression in cancer cells; AR, Klf4, and ERα expression in stromal cells; and PSA, Gleason score, and extent of disease. On the basis of these factors, patients were divided into favorable-, intermediate-, and poor-risk groups according to the number of factors present. Five-year CSS rates for the 3 groups were 90%, 32%, and 12% in the training set and 75%, 48%, and 0% in the validation set, respectively.

CONCLUSIONS

Expression levels of androgen- and estrogen signaling components and stem cell markers are powerful prognostic tools.

Epithelial-to-mesenchymal transition and estrogen receptor α mediated epithelial dedifferentiation mark the development of benign prostatic hyperplasia

BACKGROUND

Epithelial-to-mesenchymal transition (EMT) has been reported involved in the pathogenesis of fibrotic disorders and associated with stemness characteristics. Recent studies demonstrated that human benign prostatic hyperplasia (BPH) development involves accumulation of mesenchymal-like cells derived from the prostatic epithelium. However, the inductive factors of EMT in the adult prostate and the cause-and-effect relationship between EMT and stemness characteristics are not yet resolved.

METHODS

EMT expression patterns were immunohistochemically identified in the human epithelia of normal/BPH prostate tissue and in a rat BPH model induced by estrogen/androgen (E2/T, ratio 1:100) alone or in the presence of the ER antagonist raloxifene. Gene expression profiles were analyzed in micro-dissected prostatic epithelia of rat stimulated by E2/T for 3 days.

RESULTS

Two main morphological features both accompanied with EMT were observed in the epithelia of human BPH. Luminal cells undergoing EMT dedifferentiated from a cytokeratin (CK) CK18(+) /CK8(+) /CK19(+) to a CK18(-) /CK8(+) /CK19(-) phenotype and CK14 expression increased in basal epithelial cells. ERα expression was closely related to these dedifferentiated cells and the expression of EMT markers. A similar pattern of EMT events was observed in the E2/T induced rat model of BPH in comparison to the prostates of untreated rats, which could be prevented by raloxifene.

CONCLUSIONS

Epithelial and mesenchymal phenotype switching is an important mechanism in the etiology of BPH. ERα mediated enhanced estrogenic effect is a crucial inductive factor of epithelial dedifferentiation giving rise to activation of an EMT program in prostate epithelium.

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

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

Sex steroid receptor expression and localization in benign prostatic hyperplasia varies with tissue compartment

Androgens and estrogens, acting via their respective receptors, are important in benign prostatic hyperplasia (BPH). The goals of this study were to quantitatively characterize the tissue distribution and staining intensity of androgen receptor (AR) and estrogen receptor-alpha (ERα), and assess cells expressing both AR and ERα, in human BPH compared to normal prostate. A tissue microarray composed of normal prostate and BPH tissue was used and multiplexed immunohistochemistry was performed to detect AR and ERα. We used a multispectral imaging platform for automated scanning, tissue and cell segmentation and marker quantification. BPH specimens had an increased number of epithelial and stromal cells and increased percentage of epithelium. In both stroma and epithelium, the mean nuclear area was decreased in BPH relative to normal prostate. AR expression and staining intensity in epithelial and stromal cells was significantly increased in BPH compared to normal prostate. ERα expression was increased in BPH epithelium. However, stromal ERα expression and staining intensity was decreased in BPH compared to normal prostate. Double positive (AR and ERα) epithelial cells were more prevalent in BPH, and fewer double negative (AR and ERα) stromal and epithelial negative cells were observed in BPH. These data underscore the importance of tissue layer localization and expression of steroid hormone receptors in the prostate. Understanding the tissue-specific hormone action of androgens and estrogens will lead to a better understanding of mechanisms of pathogenesis in the prostate and may lead to better treatment for BPH.

The association between estrogen receptor alpha polymorphisms and the risk of prostate cancer in Slovak population

The aim of our study was to evaluate the effect of two polymorphisms in the estrogen receptor alpha, PvuII and XbaI, on the development of prostate cancer within Slovak population, as well as their correlation with selected clinical characteristics. The study was performed using 311 prostate cancer patients and 256 healthy male controls. Both polymorphisms were significantly associated with higher risk of prostate cancer development. At the same time, the CC genotype of PvuII polymorphism (OR = 1.98; 95% CI 0.94-4.21; p = 0.05) and the AG genotype of XbaI polymorphism (OR = 1.74; 95% CI 1.0-3.02; p = 0.04) significantly contributed to the development of low-grade carcinoma, while the AG and GG genotypes of the XbaI polymorphism contributed mainly to the development of high-grade prostate cancer (OR = 1.83; 95% CI 1.12-3.01; p = 0.01 and OR = 2.13; 95% CI 1.06-4.19; p = 0.03, respectively). Similarly, the AG and GG genotypes of XbaI polymorphism showed significant association with prostate cancer in patients with serum PSA level ≥10 ng/ml. Both polymorphisms were found at the same time to be more frequent in patients diagnosed before the age of 60. We conclude on the basis of these results that PvuII and XbaI polymorphisms of estrogen receptor alpha might be associated with prostate cancer risk within Slovak population. Although this is a pilot study and, as such, more detailed investigations are needed to confirm the role of these polymorphisms in prostate cancer development and progression within said Slovak population, our results might still provide a valuable basis for further research with larger patient groups.

A screen for disruptors of the retinol (vitamin A) signaling pathway

The pathway through which retinol (vitamin A) is converted to its active metabolite, all-trans-retinoic acid (atRA), and subsequent receptor-mediated regulation of gene transcription by atRA is essential for all mammal life stages. This pathway is required for normal embryonic development and maintenance of cellular phenotype in adult organisms; chemicals that cause even minor interference with its normal function are potential developmental and adult toxicants. A short-term (24 h) in vitro mode-of-action screen for detecting chemicals that disrupt this essential pathway is described. It uses the mouse pluripotent P19 stem cell in a 96-well format, RT-qPCR gene-expression assay that does not require RNA purification to detect chemicals that interfere with retinol-induced Hoxa1 gene expression, a target of retinol signaling in mammals. A total of 21 chemicals were screened at a single 45 μM concentration. Four chemicals known to disrupt the pathway in the rodent embryo (citral, disulfiram, and two rodent teratogens, nitrofen and bisdiamine) all significantly inhibited Hoxa1 upregulation by retinol. An additional four of seven chemicals with varying degrees of structural similarity to known disruptors or to the retinoid side chain, but not previously known to disrupt the pathway, were positive in the screen. The xenoestrogens, diethylstilbestrol, bisphenol A, 4-n-nonylphenol, and genistein and the phthalate esters, dibutyl phthalate and dipentyl phthalate, but not diethylhexyl phthalate, also significantly disrupted the pathway. Of the 21 chemicals tested, diethylstilbestrol was the only chemical that showed evidence in the MTT assay that cytotoxicity may have contributed to disruption of the pathway.

Prostate epithelial AR inactivation leads to increased intraprostatic androgen synthesis

BACKGROUND

Regulation of steroid synthesis within the prostate is not well understood. In this study, we examined androgen synthesis and metabolism in the mouse prostate.

METHODS

Using LC-MSMS steroid assays, immunohistochemistry and real-time PCR we examined the role of prostate epithelial AR in regulating 5αR expression and subsequent androgen metabolism by analyzing natural differences in epithelial AR expression between lobes as well as in the prostate epithelial AR knockout (PEARKO) mouse model. Subsequently, the role of intraprostatic androgen metabolism and epithelial AR in the generation and progression of prostate epithelial pathology was examined using long-term exogenous testosterone (T) + estradiol (E2) exposure.

RESULTS

Epithelial AR and 5αR2 expression as well as intraprostatic DHT followed the same lobe-specific pattern being lower in anterior than the other lobes (n = 6-8, P < 0.05). Lobe-specific 5αR2 expression was similar in PEARKO and wild-type (WT) prostate. However, PEARKO prostate had higher intraprostatic DHT content with significantly increased 5αR2 expression localized in abnormal epithelium. T + E2 treatment induced epithelial pathology was more common in PEARKO prostate compared to WT (20% vs. 2%), and was associated with increased 5αR2 expression (n = 6, P < 0.001).

CONCLUSIONS

We suggest that androgen synthesis via 5αR2 expression is driven by its own product (DHT) acting on adjacent stromal cells in a paracrine loop leading to increased in situ androgen levels in the PEARKO prostate. This may form part of a feed-forward loop that promotes the development of epithelial pathology.

β-catenin is required for prostate development and cooperates with Pten loss to drive invasive carcinoma

Prostate cancer is a major cause of male death in the Western world, but few frequent genetic alterations that drive prostate cancer initiation and progression have been identified. β-Catenin is essential for many developmental processes and has been implicated in tumorigenesis in many tissues, including prostate cancer. However, expression studies on human prostate cancer samples are unclear on the role this protein plays in this disease. We have used in vivo genetic studies in the embryo and adult to extend our understanding of the role of β-Catenin in the normal and neoplastic prostate. Our gene deletion analysis revealed that prostate epithelial β-Catenin is required for embryonic prostate growth and branching but is dispensable in the normal adult organ. During development, β-Catenin controls the number of progenitors in the epithelial buds and regulates a discrete network of genes, including c-Myc and Nkx3.1. Deletion of β-Catenin in a Pten deleted model of castration-resistant prostate cancer demonstrated it is dispensable for disease progression in this setting. Complementary overexpression experiments, through in vivo protein stabilization, showed that β-Catenin promotes the formation of squamous epithelia during prostate development, even in the absence of androgens. β-Catenin overexpression in combination with Pten loss was able to drive progression to invasive carcinoma together with squamous metaplasia. These studies demonstrate that β-Catenin is essential for prostate development and that an inherent property of high levels of this protein in prostate epithelia is to drive squamous fate differentiation. In addition, they show that β-Catenin overexpression can promote invasive prostate cancer in a clinically relevant model of this disease. These data provide novel information on cancer progression pathways that give rise to lethal prostate disease in humans.

Prostate cancer is a major cause of male death in the Western world, but few genes involved in this disease have been identified. We have undertaken an in-depth in vivo analysis in the prostate of the β-Catenin protein, which has been shown to be important in many processes during embryogenesis and has been implicated in tumorigenesis. Our studies demonstrate that β-Catenin is essential for prostate development but is dispensable in the normal adult organ. Analysis of a mouse model of a frequently mutated human prostate tumour suppressor, Pten loss, revealed that β-Catenin is not required for neoplastic formation in this model, even in castrated conditions. However, increased β-Catenin levels can cooperate with Pten loss to promote the progression of aggressive invasive prostate cancer together with squamous metaplasia. These data uncover the role of β-Catenin in the prostate and provide new insights on how pathways interact to drive human prostate cancer.

Human epithelial basal cells are cells of origin of prostate cancer, independent of CD133 status

Normal prostatic epithelium is composed of basal and luminal cells. Prostate cancer can be initiated in both benign basal and luminal stem cells, but because basal cell markers are not expressed in patient tumors, the former result was unexpected. Since the cells of origin of prostate cancer are important therapeutic targets, we sought to provide further proof that basal stem cells have tumorigenic potential. Prostatic basal cells were enriched based on α2β1integrin(hi) expression and further enriched for stem cells using CD133 in nontumorigenic BPH-1 cells. Human embryonic stem cells (hESCs) were also used as a source of normal stem cells. To test their tumorigenicity, we used two alternate stromal-based approaches; (a) recombination with human cancer-associated fibroblasts (CAFs) or (b) recombination with embryonic stroma (urogenital mesenchyme) and treated host mice with testosterone and 17β-estradiol. Enriched α2β1integrin(hi) basal cells from BPH-1 cells resulted in malignant tumor formation using both assays of tumorigenicity. Surprisingly, the tumorigenic potential did not reside in the CD133(+) stem cells but was consistently observed in the CD133(-) population. CAFs also failed to induce prostatic tumors from hESCs. These data confirmed that benign human basal cells include cells of origin of prostate cancer and reinforced their importance as therapeutic targets. In addition, our data suggested that the more proliferative CD133(-) basal cells are more susceptible to tumorigenesis compared to the CD133(+)-enriched stem cells. These findings challenge the current dogma that normal stem cells and cells of origin of cancer are the same cell type(s).

Current concepts and significance of estrogen receptor β in prostate cancer

An increasing amount of evidence points at important roles for estrogen receptors in prostate carcinogenesis and progression. Of the two estrogen receptors, estrogen receptor β is the most prominent within the prostate gland. Although there is much yet to be known, the findings from the discovery of the receptor in 1996 until now point at a role of the receptor in maintaining differentiation and reducing cellular proliferation in the prostate. Moreover, estrogen receptor β is the main target for phytoestrogens, perhaps at least partially explaining the difference in incidence of prostate cancer in the Western world compared to Asia where the intake of soy-based, phytoestrogen-rich food is higher. The tumor suppressive capability of estrogen receptor β makes it a promising drug target for the treatment and prevention of prostate cancer. This review will focus on different aspects of estrogen receptor signaling and prostate cancer.

Aggressive prostate cancer is prevented in ERαKO mice and stimulated in ERβKO TRAMP mice

Previous evidence suggests soy genistein may be protective against prostate cancer, but whether this protection involves an estrogen receptor (ER)-dependent mechanism is unknown. To test the hypothesis that phytoestrogens may act through ERα or ERβ to play a protective role against prostate cancer, we bred transgenic mice lacking functional ERα or ERβ with transgenic adenocarcinoma of mouse prostate (TRAMP) mice. Dietary genistein reduced the incidence of cancer in ER wild-type (WT)/transgenic adenocarcinoma of mouse prostate mice but not in ERα knockout (KO) or ERβKO mice. Cancer incidence was 70% in ERWT mice fed the control diet compared with 47% in ERWT mice fed low-dose genistein (300 mg/kg) and 32% on the high-dose genistein (750 mg/kg). Surprisingly, genistein only affected the well differentiated carcinoma (WDC) incidence but had no effect on poorly differentiated carcinoma (PDC). No dietary effects have been observed in either of the ERKO animals. We observed a very strong genotypic influence on PDC incidence, a protective effect in ERαKO (only 5% developed PDC), compared with 19% in the ERWT, and an increase in the incidence of PDC in ERβKO mice to 41%. Interestingly, immunohistochemical analysis showed ERα expression changing from nonnuclear in WDC to nuclear in PDC, with little change in ERβ location or expression. In conclusion, genistein is able to inhibit WDC in the presence of both ERs, but the effect of estrogen signaling on PDC is dominant over any dietary treatment, suggesting that improved differential targeting of ERα vs. ERβ would result in prevention of advanced prostate cancer.

Reduced prostate branching morphogenesis in stromal fibroblast, but not in epithelial, estrogen receptor α knockout mice

Early studies suggested that estrogen receptor alpha (ERα) is involved in estrogen-mediated imprinting effects in prostate development. We recently reported a more complete ERα knockout (KO) mouse model via mating β-actin Cre transgenic mice with floxed ERα mice. These ACTB-ERαKO male mice showed defects in prostatic branching morphogenesis, which demonstrates that ERα is necessary to maintain proliferative events in the prostate. However, within which prostate cell type ERα exerts those important functions remains to be elucidated. To address this, we have bred floxed ERα mice with either fibroblast-specific protein (FSP)-Cre or probasin-Cre transgenic mice to generate a mouse model that has deleted ERα gene in either stromal fibroblast (FSP-ERαKO) or epithelial (pes-ERαKO) prostate cells. We found that circulating testosterone and fertility were not altered in FSP-ERαKO and pes-ERαKO male mice. Prostates of FSP-ERαKO mice have less branching morphogenesis compared to that of wild-type littermates. Further analyses indicated that loss of stromal ERα leads to increased stromal apoptosis, reduced expression of insulin-like growth factor-1 (IGF-1) and FGF10, and increased expression of BMP4. Collectively, we have established the first in vivo prostate stromal and epithelial selective ERαKO mouse models and the results from these mice indicated that stromal fibroblast ERα plays important roles in prostatic branching morphogenesis via a paracrine fashion. Selective deletion of the ERα gene in mouse prostate epithelial cells by probasin-Cre does not affect the regular prostate development and homeostasis.

The role of the myofibroblast in tumor stroma remodeling

Since its first description in wound granulation tissue, the myofibroblast has been recognized to be a key actor in the epithelial-mesenchymal cross-talk that plays a crucial role in many physiological and pathological situations, such as regulation of prostate development, ventilation-perfusion in lung alveoli or organ fibrosis. The presence of myofibroblasts in the stroma reaction to epithelial tumors is well established and many data are accumulating which suggest that the stroma compartment is an active participant in tumor onset and/or evolution. In this review we summarize the evidence in favor of this concept, the main mechanisms that regulate myofibroblast differentiation and function, as well as the biophysical and biochemical factors possibly involved in epithelial-stroma interactions, using liver carcinoma as main model, in view of achieving a better understanding of tumor progression mechanisms and of tools directed toward stroma as eventual therapeutic target.

Loss of epithelial oestrogen receptor α inhibits oestrogen-stimulated prostate proliferation and squamous metaplasia via in vivo tissue selective knockout models

Squamous metaplasia (SQM) is a specific phenotype in response to oestrogen in the prostate and oestrogen receptor (ER) α is required to mediate this response. Previous studies utilizing tissue recombination with seminal vesicle (SV) mesenchyme and prostatic ductal tips from wild type and ERαKO mice suggested that both epithelial and stromal ERα are necessary for SQM. However, tissue recombination is conducted in the renal capsule of immune-deficient mice, in which the microenvironment is different from normal prostate microenvironment in the intact mice. Furthermore, whether the requirement of stromal ERα in the SV for developing SQM is the same as in the prostate is unknown. Therefore, there is a clear need to evaluate the respective roles of ERα in prostate epithelial versus stromal compartments in the intact mouse. Here we generated a mouse model that has selectively lost ERα in either stromal (FSP-ERαKO) or epithelial prostate cells (pes-ERαKO) to determine the requirements of ERα for oestrogen-stimulated prostate proliferation and SQM. Our results indicated that FSP-ERαKO prostates develop full and uniform SQM, which suggests that loss of the majority (~65%) of stromal ERα will not influence oestrogen-mediated SQM. In contrast, loss of epithelial ERα inhibits oestrogen-mediated prostate growth and SQM evidenced by decreasing cytokertin 10 positive squamous cell stratification and differentiation, by reduced ERα protein expression in SQM compared to wild type mice ERα, and by the presence of normal proliferative activities in the oestrogen-treated pes-ERαKO prostates. These in vivo results suggest that epithelial ERα is required for oestrogen-mediated proliferative response and could be an appropriate target for preventing aberrant oestrogen signalling in the prostate.

Estrogenic environmental chemicals and drugs: mechanisms for effects on the developing male urogenital system

Development and differentiation of the prostate from the fetal urogenital sinus (UGS) is dependent on androgen action via androgen receptors (AR) in the UGS mesenchyme. Estrogens are not required for prostate differentiation but do act to modulate androgen action. In mice exposure to exogenous estrogen during development results in permanent effects on adult prostate size and function, which is mediated through mesenchymal estrogen receptor (ER) alpha. For many years estrogens were thought to inhibit prostate growth because estrogenic drugs studied were administered at very high concentrations that interfered with normal prostate development. There is now extensive evidence that exposure to estrogen at very low concentrations during the early stages of prostate differentiation can stimulate fetal/neonatal prostate growth and lead to prostate disease in adulthood. Bisphenol A (BPA) is an environmental endocrine disrupting chemical that binds to both ER receptor subtypes as well as to AR. Interest in BPA has increased because of its prevalence in the environment and its detection in over 90% of people in the USA. In tissue culture of fetal mouse UGS mesenchymal cells, BPA and estradiol stimulated changes in the expression of several genes. We discuss here the potential involvement of estrogen in regulating signaling pathways affecting cellular functions relevant to steroid hormone signaling and metabolism and to inter- and intra-cellular communications that promote cell growth. The findings presented here provide additional evidence that BPA and the estrogenic drug ethinylestradiol disrupt prostate development in male mice at administered doses relevant to human exposures.

Interaction between ionizing radiation and estrogen: what we are missing?

Following complexity as a new approach in science of 21st century biomonitoring of biological effects caused by ionizing radiation received an option of a new dimension. Insight in biological response of mammals to ionizing radiation exposure by integration of genome, non-genome and distant organ bystander effects will significantly change evaluation of health risk and preventive measures. Impact of estrogen on carcinogenesis caused by occupational or accidental exposure to ionizing radiation additionally enables biodosimetry to recognize vulnerable subpopulations according to gender and age. Estrogen, as a potent molecule involved in number of biological pathways during development and adulthood, shows close interaction with pathological processes launched by overexposure to ionizing radiation which should be included in future research and radiation protection.

Smooth muscle cell-specific knockout of androgen receptor: a new model for prostatic disease

Androgen-driven stromal-epithelial interactions play a key role in normal prostate development and function as well as in the progression of common prostatic diseases such as benign prostatic hyperplasia and prostate cancer. However, exactly how, and via which cell type, androgens mediate their effects in the adult prostate remains unclear. This study investigated the role for smooth muscle (SM) androgen signaling in normal adult prostate homeostasis and function using mice in which androgen receptor was selectively ablated from prostatic SM cells. In adulthood the knockout (KO) mice displayed a 44% reduction in prostate weight and exhibited histological abnormalities such as hyperplasia, inflammation, fibrosis, and reduced expression of epithelial, SM, and stem cell identify markers (e.g. p63 reduced by 27% and Pten by 31%). These changes emerged beyond puberty and were not explained by changes in serum hormones. Furthermore, in response to exogenous estradiol, adult KO mice displayed an 8.5-fold greater increase in prostate weight than controls and developed urinary retention. KO mice also demonstrated a reduced response to castration compared with controls. Together these results demonstrate that prostate SM cells are vital in mediating androgen-driven stromal-epithelial interactions in adult mouse prostates, determining cell identity and function and limiting hormone-dependent epithelial cell proliferation. This novel mouse model provides new insight into the possible role for SM androgen action in prostate disease.

The different roles of ER subtypes in cancer biology and therapy

By eliciting distinct transcriptional responses, the oestrogen receptors (ERs) ERα and ERβ exert opposite effects on cellular processes that include proliferation, apoptosis and migration and that differentially influence the development and the progression of cancer. Perturbation of ER subtype-specific expression has been detected in various types of cancer, and the differences in the expression of ERs are correlated with the clinical outcome. The changes in the bioavailability of ERs in tumours, together with their specific biological functions, promote the selective restoration of their activity as one of the major therapeutic approaches for hormone-dependent cancers.

PPARγ: a molecular link between systemic metabolic disease and benign prostate hyperplasia

The emergent epidemic of metabolic syndrome and its complex list of sequelae mandate a more thorough understanding of benign prostatic hyperplasia and lower urinary tract symptoms (BPH/LUTS) in the context of systemic metabolic disease. Here we discuss the nature and origins of BPH, examine its role as a component of LUTS and review retrospective clinical studies that have drawn associations between BPH/LUTS and type II diabetes, inflammation and dyslipidemia. PPARγ signaling, which sits at the nexus of systemic metabolic disease and BPH/LUTS through its regulation of inflammation and insulin resistance, is proposed as a candidate for molecular manipulation in regard to BPH/LUTS. Finally, we introduce new cell and animal models that are being used to study the consequences of obesity, diabetes and inflammation on benign prostatic growth.

Exposure to ethinylestradiol during prenatal development and postnatal supplementation with testosterone causes morphophysiological alterations in the prostate of male and female adult gerbils

Steroids perform significant functions in prostatic development and growth, so that interferences of this equilibrium may predispose the gland to the development of diseases during the life. Embryonic and neonatal exposure to xenoestrogens, many of them with endocrine-disrupting potential, has been related to the induction of disturbances in reproductive system organs. Thus, this study aimed to analyse morphological and immunocytochemical aspects of prostate in both male and female adult gerbils either exposed to ethinylestradiol during the prenatal phase (pregnant females received 10 μg/kg, by gavage) (EE group) or exposed to testosterone (1 mg/kg) during the postnatal period (EE/T group). Serological analysis revealed a rise in estradiol levels in adult males and females of the EE group. A higher incidence of prostatic intraepithelial neoplasia (PIN) was observed in the male and female prostate of the treated groups, besides an increase in collagen and reticular fibres. Immunocytochemistry showed an increase in prostatic epithelial cells immunoreactive to AR and a presence of a smooth muscle layer, evidenced by α actin, in injured regions this way absent in prostatic epithelial buds. These pieces of evidence suggest that the alterations verified in the prostate in adulthood of both sexes may be due to the high oestrogen levels. Either males or females of the EE/T group showed normalized estradiol levels, although prostatic lesions could be observed. While the prostatic gland of male gerbils was more affected than the female prostate, this study showed that the exposure to EE during this critical period of development disrupts the prostate of both sexes in terms of prostatic lesions.

The role of oestrogen in the pathogenesis of obesity, type 2 diabetes, breast cancer and prostate disease

A detailed review of the literature was performed in a bid to identify the presence of a common link between specific hormone interactions and the increasing prevalence of global disease. The synergistic action of unopposed oestrogen and leptin, compounded by increasing insulin, cortisol and xeno-oestrogen exposure directly initiate, promote and exacerbate obesity, type 2 diabetes, uterine overgrowth, prostatic enlargement, prostate cancer and breast cancer. Furthermore these hormones significantly contribute to the incidence and intensity of anxiety and depression, Alzheimer's disease, heart disease and stroke. This review, in collaboration with hundreds of evidence-based clinical researchers, correlates the significant interactions these hormones exert upon the upregulation of p450 aromatase, oestrogen, leptin and insulin receptor function; the normal status quo of their binding globulins; and how adduct formation alters DNA sequencing to ultimately produce an array of metabolic conditions ranging from menopausal symptoms and obesity to Alzheimer's disease and breast and prostate cancer. It reveals the way that poor diet, increased stress, unopposed endogenous oestrogens, exogenous oestrogens, pesticides, xeno-oestrogens and leptin are associated with increased aromatase activity, and how its products, increased endogenous oestrogen and lowered testosterone, are associated with obesity, type 2 diabetes, Alzheimer's disease and oestrogenic disease. This controversial break-through represents a paradigm shift in medical thinking, which can prevent the raging pandemic of diabetes, obesity and cancer currently sweeping the world, and as such, it will reshape health initiatives, reduce suffering, prevent waste of government expenditure and effectively transform preventative medicine and global health care for decades.