Estrogen receptor alpha drives proliferation in PTEN-deficient prostate carcinoma by stimulating survival signaling, MYC expression and altering glucose sensitivity

The estrogen signaling pathway reprograms prostate cancer cell metabolism and supports proliferation and disease progression

Just like the androgen receptor (AR), the estrogen receptor α (ERα) is expressed in the prostate and is thought to influence prostate cancer (PCa) biology. Yet the incomplete understanding of ERα functions in PCa hinders our ability to fully comprehend its clinical relevance and restricts the repurposing of estrogen-targeted therapies for the treatment of this disease. Using 2 human PCa tissue microarray cohorts, we first demonstrate that nuclear ERα expression was heterogeneous among patients, being detected in only half of the tumors. Positive nuclear ERα levels were correlated with disease recurrence, progression to metastatic PCa, and patient survival. Using in vitro and in vivo models of the normal prostate and PCa, bulk and single-cell RNA-Seq analyses revealed that estrogens partially mimicked the androgen transcriptional response and activated specific biological pathways linked to proliferation and metabolism. Bioenergetic flux assays and metabolomics confirmed the regulation of cancer metabolism by estrogens, supporting proliferation. Using cancer cell lines and patient-derived organoids, selective estrogen receptor modulators, a pure anti-estrogen, and genetic approaches impaired cancer cell proliferation and growth in an ERα-dependent manner. Overall, our study revealed that, when expressed, ERα functionally reprogrammed PCa metabolism, was associated with disease progression, and could be targeted for therapeutic purposes.

Fulvestrant increases the susceptibility of enzalutamide-resistant prostate cancer cells to NK-mediated lysis

BACKGROUND

Enzalutamide, a next-generation antiandrogen agent, is approved for the treatment of metastatic castration-resistant prostate cancer (CRPC). While enzalutamide has been shown to improve time to progression and extend overall survival in men with CRPC, the majority of patients ultimately develop resistance to treatment. Immunotherapy approaches have shown limited clinical benefit in this patient population; understanding resistance mechanisms could help develop novel and more effective treatments for CRPC. One of the mechanisms involved in tumor resistance to various therapeutics is tumor phenotypic plasticity, whereby carcinoma cells acquire mesenchymal features with or without the loss of classical epithelial characteristics. This work investigated a potential link between enzalutamide resistance, tumor phenotypic plasticity, and resistance to immune-mediated lysis in prostate cancer.

METHODS

Models of prostate cancer resistant to enzalutamide were established by long-term exposure of human prostate cancer cell lines to the drug in culture. Tumor cells were evaluated for phenotypic features in vitro and in vivo, as well as for sensitivity to immune effector cell-mediated cytotoxicity.

RESULTS

Resistance to enzalutamide was associated with gain of mesenchymal tumor features, upregulation of estrogen receptor expression, and significantly reduced tumor susceptibility to natural killer (NK)-mediated lysis, an effect that was associated with decreased tumor/NK cell conjugate formation with enzalutamide-resistant cells. Fulvestrant, a selective estrogen receptor degrader, restored the formation of target/NK cell conjugates and increased susceptibility to NK cell lysis in vitro. In vivo, fulvestrant demonstrated antitumor activity against enzalutamide-resistant cells, an effect that was associated with activation of NK cells.

CONCLUSION

NK cells are emerging as a promising therapeutic approach in prostate cancer. Modifying tumor plasticity via blockade of estrogen receptor with fulvestrant may offer an opportunity for immune intervention via NK cell-based approaches in enzalutamide-resistant CRPC.

Trends in estrogen and progesterone receptors in prostate cancer: a bibliometric analysis

Introduction

The bibliometric analysis aims to identify research trends in estrogen receptor (ERs) and progesterone receptor (PRs) in prostate cancer (PCa), and also discuss the hotspots and directions of this field.

Methods

835 publications were sourced from the Web of Science database (WOS) from 2003 to 2022. Citespace, VOSviewer, and Bibliometrix were used for the bibliometric analysis.

Results

The number of published publications increased in early years, but declined in the last 5 years. The United States was the leading country in citations, publications, and top institutions. Prostate and Karolinska Institutet were the most publications of journal and institution, respectively. Jan-Ake Gustafsson was the most influential author based on the number of citations/publications. The most cited paper was "Estrogen receptors and human disease" by Deroo BJ, published in the Journal of Clinical Investigation. The most frequently used keywords were PCa (n = 499), gene-expression (n = 291), androgen receptor (AR) (n = 263), and ER (n = 341), while ERb (n = 219) and ERa (n = 215) further emphasized the importance of ER.

Conclusions

This study provides useful guidance that ERa antagonists, ERb agonists, and the combination of estrogen with androgen deprivation therapy (ADT) will potentially serve as a new treatment strategy for PCa. Another interesting topic is relationships between PCa and the function and mechanism of action of PRs subtypes. The outcome will assist scholars in gaining a comprehensive understanding of the current status and trends in the field, and provide inspiration for future research.

Molecular Similarities and Differences between Canine Prostate Cancer and Human Prostate Cancer Variants

Dogs are one of few species that naturally develop prostate cancer (PCa), which clinically resembles aggressive, advanced PCa in humans. Moreover, PCa-tumor samples from dogs are often androgen receptor (AR)-negative and may enrich our understanding of AR-indifferent PCa in humans, a highly lethal subset of PCa for which few treatment modalities are available This narrative review discusses the molecular similarities between dog PCa and specific human-PCa variants, underscoring the possibilities of using the dog as a novel pre-clinical animal model for human PCa, resulting in new therapies and diagnostics that may benefit both species.

Prostate cancer in transgender women: considerations for screening, diagnosis and management

Transgender individuals represent 0.55% of the US population, equivalent to 1.4 million transgender adults. In transgender women, feminisation can include a number of medical and surgical interventions. The main goal is to deprive the phenotypically masculine body of androgens and simultaneously provide oestrogen therapy for feminisation. In gender-confirming surgery (GCS) for transgender females, the prostate is usually not removed. Due to limitations of existing cohort studies, the true incidence of prostate cancer in transgender females is unknown but is thought to be less than the incidence among cis-gender males. It is unclear how prostate cancer develops in androgen-deprived conditions in these patients. Six out of eleven case reports in the literature presented with metastatic disease. It is thought that androgen receptor-mediated mechanisms or tumour-promoting effects of oestrogen may be responsible. Due to the low incidence of prostate cancer identified in transgender women, there is little evidence to drive specific screening recommendations in this patient subpopulation. The treatment of early and locally advanced prostate cancer in these patients warrants an individualised thoughtful approach with input from patients' reconstructive surgeons. Both surgical and radiation treatment for prostate cancer in these patients can profoundly impact the patient's quality of life. In this review, we discuss the evidence surrounding screening and treatment of prostate cancer in transgender women and consider the current gaps in our knowledge in providing evidence-based guidance at the molecular, genomic and epidemiological level, for clinical decision-making in the management of these patients.

Prostate Cancer Review: Genetics, Diagnosis, Treatment Options, and Alternative Approaches

Simple Summary

Prostate cancer affects men of all racial and ethnic groups and leads to higher rates of mortality in those belonging to a lower socioeconomic status due to late detection of the disease. There is growing evidence that suggests the contribution of an individual’s genetic profile to prostate cancer. Currently used prostate cancer treatments have serious adverse effects; therefore, new research is focusing on alternative treatment options such as the use of genetic biomarkers for targeted gene therapy, nanotechnology for controlled targeted treatment, and further exploring medicinal plants for new anticancer agents. In this review, we describe the recent advances in prostate cancer research.

Abstract

Prostate cancer is one of the malignancies that affects men and significantly contributes to increased mortality rates in men globally. Patients affected with prostate cancer present with either a localized or advanced disease. In this review, we aim to provide a holistic overview of prostate cancer, including the diagnosis of the disease, mutations leading to the onset and progression of the disease, and treatment options. Prostate cancer diagnoses include a digital rectal examination, prostate-specific antigen analysis, and prostate biopsies. Mutations in certain genes are linked to the onset, progression, and metastasis of the cancer. Treatment for localized prostate cancer encompasses active surveillance, ablative radiotherapy, and radical prostatectomy. Men who relapse or present metastatic prostate cancer receive androgen deprivation therapy (ADT), salvage radiotherapy, and chemotherapy. Currently, available treatment options are more effective when used as combination therapy; however, despite available treatment options, prostate cancer remains to be incurable. There has been ongoing research on finding and identifying other treatment approaches such as the use of traditional medicine, the application of nanotechnologies, and gene therapy to combat prostate cancer, drug resistance, as well as to reduce the adverse effects that come with current treatment options. In this article, we summarize the genes involved in prostate cancer, available treatment options, and current research on alternative treatment options.

Chronic coexposure to arsenic and estrogen potentiates genotoxic estrogen metabolic pathway and hypermethylation of DNA glycosylase MBD4 in human prostate epithelial cells

BACKGROUND

Previously we reported that arsenic and estrogen cause synergistic effects in the neoplastic transformation of human prostate epithelial cells. In addition to receptor-mediated pathways, DNA-reactive estrogen metabolites have also been shown to play a critical role in mutagenicity and carcinogenicity. Both estrogen and arsenic are known prostate carcinogens, however, the effect of coexposure to these two chemicals on genes involved in estrogen metabolism is not known. Therefore, the objective of this study was to evaluate the role of arsenic and estrogen coexposure on the expression of estrogen receptors and estrogen metabolism-associated genes. Earlier, we also reported the synergistic effect of arsenic and estrogen on decreased expression of MBD4 genes that play an important role in DNA repair through its DNA glycosylase activity. To further understand the mechanism, the promoter methylation of this gene was also analyzed.

METHODS

Total RNA and protein were isolated from RWPE-1 human prostate epithelial cells that were coexposed to arsenic and estrogen for a chronic duration (6 months). The expression of estrogen receptors, estrogen metabolism associated phase I genes (CYP 1A1, 1A2, 3A4, and 1B1) and phase II gene catechol-O-methyltransferase (COMT), as well as antioxidant MnSOD, were analyzed either at the RNA level by quantitative reverse transcriptase-polymerase chain reaction or at the protein level by western blot. Promoter methylation of MBD4 was analyzed by pyrosequencing.

RESULTS

Expression of MnSOD and phase I genes that convert E₂ into genotoxic metabolites 2-OH-E₂ and 4-OH-E₂ were significantly increased, whereas the expression of phase II gene COMT that detoxifies estrogen metabolites was significantly decreased in arsenic and estrogen coexposed cells. MBD4 promoter was hypermethylated in arsenic and estrogen coexposed cells. Coexposure to arsenic and estrogen has synergistic effects on the expression of these genes as well as in MBD4 promoter hypermethylation.

CONCLUSIONS

These novel findings suggest that coexposure to arsenic and estrogen acts synergistically in the activation of not only the estrogen receptors but also the genes associated with genotoxic estrogen metabolism and epigenetic inactivation of DNA glycosylase MBD4. Together, these genetic and epigenetic aberrations provide the molecular basis for the potentiation of carcinogenicity of arsenic and estrogen coexposure in prostate epithelial cells.

Estrogen receptor expression is modulated in human and mouse prostate epithelial cells during cancer progression

Substantial data posit estrogen receptors (ERs) as promising targets for prostate cancer (PCa) therapeutics. However, the trials on assessing the chemo-preventive or therapeutic potential of ER targeting drugs or selective estrogen receptor modulators (SERMs) have not yet established their clinical benefits. This could be ascribed to a possible modulation in the ER expression during PCa progression. Further it is warranted to test various ER targeting drugs in appropriate preclinical models that simulate human ER expression pattern during PCa progression. The study was undertaken to revisit the existing data on the epithelial ER expression pattern in human cancerous prostates and experimentally determine whether these patterns are replicated in TRAMP (Transgenic Adenocarcinoma of Mouse Prostate) mice, a model for human PCa. Estradiol (E2) binding to the plasma membrane of the epithelial cells and its modulation during the PCa progression in TRAMP were also investigated. A reassessment of the existing data revealed a trend towards downregulation in the epithelial expression of wild-type ESR1 transcripts in high-grade PCa, compared to non-cancerous prostate in humans. Next, epithelial cell-enriched populations from TRAMP prostates (TP) displaying low-grade prostatic intraepithelial neoplasia (LGPIN), high-grade PIN (HGPIN), HGPIN with well-differentiated carcinoma (PIN + WDC), WDC (equivalent to grade 2/3 human PCa), and poorly-differentiated carcinoma (PDC-equivalent to grade 4/5 human PCa) revealed significantly higher Esr1 and Esr2 levels in HGPIN and significantly reduced levels in WDC, compared to respective age-matched control prostates. These patterns for the nuclear ERs were similar to the trend shown by E2 binding to the plasma membrane of the epithelial cells during PCa progression in TRAMP. E2 binding to epithelial cells (EpCAM+), though significantly higher in TPs displaying LGPIN, decreased significantly as the disease progressed to WDC. The study highlights a reduction in the epithelial ESR level with the PCa progression and this pattern was evident in both humans and TRAMP. These observations may have major implications in refining PCa therapeutics targeting ER.

Selective estrogen receptor modulators contribute to prostate cancer treatment by regulating the tumor immune microenvironment

Prostate cancer (PC) has previously been established as a cold tumor and develops in an inert immunosuppressive environment. Current research focuses on altering the immune microenvironment of PC from cold to hot; thus, in the present review, the diverse roles of estrogen and estrogen receptor (ER) signaling was examined in the tumor cell and tumor immune microenvironment (TIM). We hypothesized that ERα promotes PC progression and ERβ impedes epithelial-mesenchymal transition in PC cells, while in the TIM, ERβ mediates the immunosuppressive environment, and low levels of ERα is associated with disease development. Selective estrogen receptor modulators (SERMs) or selective ER degraders play diverse roles in the regulation of ER isoforms. Patients with PC may benefit from the use of SERMs, including raloxifene, in combination with anti-PD1/PD-L1 checkpoint immunotherapy, or TGF-β or Wnt antagonists. The present review demonstrated that immunotherapy-based strategies combined with SERMs may be an option for the future of PC-targeting therapy.

Impacts of endocrine-disrupting chemicals on prostate function and cancer

Because of their historical mode of action, endocrine-disrupting chemicals (EDCs) are associated with sex-steroid receptors, namely the two estrogen receptors (ERα and ERβ) and the androgen receptor (AR). Broadly, EDCs can modulate sex-steroid receptor functions. They can also indirectly impact the androgen and estrogen pathways by influencing steroidogenesis, expression of AR or ERs, and their respective activity as transcription factors. Additionally, many of these chemicals have multiple cellular targets other than sex-steroid receptors, which results in a myriad of potential effects in humans. The current article reviews the association between prostate cancer and the endocrine-disrupting functions of four prominent EDC families: bisphenols, phthalates, phytoestrogens, and mycoestrogens. Results from both in vitro and in vivo models are included and discussed to better assess the molecular mechanisms by which EDCs can modify prostate biology. To overcome the heterogeneity of results published, we established common guidelines to properly study EDCs in the context of endocrine diseases. Firstly, the expression of sex-steroid receptors in the models used must be determined before testing. Then, in parallel to EDCs, pharmacological compounds acting as positive (agonists) and negative controls (antagonists) have to be employed. Finally, EDCs need to be used in a precise range of concentrations to modulate sex-steroid receptors and avoid off-target effects. By adequately integrating molecular endocrinology aspects in EDC studies and identifying their underlying molecular mechanisms, we will truly understand their impact on prostate cancer and distinguish those that favor the progression of the disease from those that slow down tumor development.

Estrogen Receptors-Mediated Apoptosis in Hormone-Dependent Cancers

It is known that estrogen stimulates growth and inhibits apoptosis through estrogen receptor(ER)-mediated mechanisms in many cancer cell types. Interestingly, there is strong evidence that estrogens can also induce apoptosis, activating different ER isoforms in cancer cells. It has been observed that E2/ERα complex activates multiple pathways involved in both cell cycle progression and apoptotic cascade prevention, while E2/ERβ complex in many cases directs the cells to apoptosis. However, the exact mechanism of estrogen-induced tumor regression is not completely known. Nevertheless, ERs expression levels of specific splice variants and their cellular localization differentially affect outcome of estrogen-dependent tumors. The goal of this review is to provide a general overview of current knowledge on ERs-mediated apoptosis that occurs in main hormone dependent-cancers. Understanding the molecular mechanisms underlying the induction of ER-mediated cell death will be useful for the development of specific ligands capable of triggering apoptosis to counteract estrogen-dependent tumor growth.

Polysome Fractionation for Transcriptome-Wide Studies of mRNA Translation

Protein synthesis and degradation determine the relationship between mRNA and corresponding protein amounts. This relationship can change in a dynamic and selective fashion when translational efficiencies of transcript subsets are altered downstream of, for example, translation factors and/or RNA binding proteins. Notably, even transcription factors such as estrogen receptor alpha (ERα) can modulate mRNA translation in a transcript-selective manner. Yet, despite ample evidence suggesting a key role for mRNA translation in shaping the proteome in health and disease, it remains largely unexplored. Here, we present a guide for the extraction of mRNA engaged in translation using polysome fractionation with linear and optimized sucrose gradients. The isolated polysome-associated RNA is then quantified, in parallel with total mRNA from the same conditions, using methods such as RNA sequencing; and the resulting data set is analyzed to derive transcriptome-wide insights into how mRNA translation is modulated. The methods we describe are applicable to cultured cells, small numbers of FACS-isolated primary cells, and small tissue samples from biobanks or animal studies. Accordingly, this approach can be applied to study in detail how ERα and other factors control gene expression by selectively modulating mRNA translation both in vitro and in vivo.

Regulation of mRNA Translation by Hormone Receptors in Breast and Prostate Cancer

Simple Summary

The estrogen and androgen receptors (ER, AR) are key oncogenic drivers and therapeutic targets in breast and prostate cancer, respectively. These receptors bind to DNA and regulate gene expression but emerging evidence indicates that they also play important roles in controlling the process of mRNA translation, which dictates cellular protein production. Here, we review the mechanisms by which abnormal activities of ER and AR can dysregulate mRNA translation in breast and prostate cancer cells. Specifically, we explore how the intricate cellular signalling pathways that keep mRNA translation in check are perturbed by aberrant ER and AR signalling, which can lead to enhanced cancer cell growth. We also discuss the potential of targeting mRNA translation as a strategy to treat patients with breast and prostate cancer.

Abstract

Breast and prostate cancer are the second and third leading causes of death amongst all cancer types, respectively. Pathogenesis of these malignancies is characterised by dysregulation of sex hormone signalling pathways, mediated by the estrogen receptor-α (ER) in breast cancer and androgen receptor (AR) in prostate cancer. ER and AR are transcription factors whose aberrant function drives oncogenic transcriptional programs to promote cancer growth and progression. While ER/AR are known to stimulate cell growth and survival by modulating gene transcription, emerging findings indicate that their effects in neoplasia are also mediated by dysregulation of protein synthesis (i.e., mRNA translation). This suggests that ER/AR can coordinately perturb both transcriptional and translational programs, resulting in the establishment of proteomes that promote malignancy. In this review, we will discuss relatively understudied aspects of ER and AR activity in regulating protein synthesis as well as the potential of targeting mRNA translation in breast and prostate cancer.

Association between the polygenic liabilities for prostate cancer and breast cancer with biochemical recurrence after radical prostatectomy for localized prostate cancer

Prostate and breast cancers are hormone-related malignancies and are characterized by a complex interplay of hundreds of susceptibility loci throughout the genome. Prostate cancer could be inhibited by eliminating androgens through castration or estrogen administration, thus facilitating long-term treatment of prostate cancer; however, the role of estrogen in prostate cancer remains unclear. This study aimed to determine whether polygenic risk scores (PRSs) comprising combinations of genome-wide susceptibility variants influence the clinical outcomes of prostate cancer patients. The study subjects were recruited from four medical centers in Taiwan, and genome-wide genotyping data were obtained from 643 prostate cancer patients. We derived the PRS for prostate cancer (PRS-PC) and for breast cancer (PRS-BC) for each patient. The association between the PRS-PC/PRS-BC at the age of prostate cancer onset and recurrence within seven years was evaluated using a regression model adjusted for population stratification components. A higher PRS-PC was associated with an earlier onset age for prostate cancer (beta in per SD increase in PRS = -0.89, P = 0.0008). In contrast, a higher PRS-BC was associated with an older onset age for prostate cancer (beta = 0.59, P = 0.02). PRS-PC was not associated with the risk of recurrence (hazard ratio = 1.03, P = 0.67), whereas a higher PRS-BC was associated with a low recurrence risk (hazard ratio = 0.86, P = 0.03). These results indicate that the genetic predisposition to breast cancer is associated with a low risk of prostate cancer recurrence. Further studies are warranted to explore the role of breast cancer susceptibility variants and estrogen signaling in prostate cancer progression.

Endocrinology of the Aging Prostate: Current Concepts

Benign prostate hyperplasia (BPH), one of the most common diseases in older men, adversely affects quality-of-life due to the presence of low urinary tract symptoms (LUTS). Numerous data support the presence of an association between BPH-related LUTS (BPH-LUTS) and metabolic syndrome (MetS). Whether hormonal changes occurring in MetS play a role in the pathogenesis of BPH-LUTS is a debated issue. Therefore, this article aimed to systematically review the impact of hormonal changes that occur during aging on the prostate, including the role of sex hormones, insulin-like growth factor 1, thyroid hormones, and insulin. The possible explanatory mechanisms of the association between BPH-LUTS and MetS are also discussed. In particular, the presence of a male polycystic ovarian syndrome (PCOS)-equivalent may represent a possible hypothesis to support this link. Male PCOS-equivalent has been defined as an endocrine syndrome with a metabolic background, which predisposes to the development of type II diabetes mellitus, cardiovascular diseases, prostate cancer, BPH and prostatitis in old age. Its early identification would help prevent the onset of these long-term complications.

Revisiting prostate cancer metabolism: From metabolites to disease and therapy

Prostate cancer (PCa), one of the most commonly diagnosed cancers worldwide, still presents important unmet clinical needs concerning treatment. In the last years, the metabolic reprogramming and the specificities of tumor cells emerged as an exciting field for cancer therapy. The unique features of PCa cells metabolism, and the activation of specific metabolic pathways, propelled the use of metabolic inhibitors for treatment. The present work revises the knowledge of PCa metabolism and the metabolic alterations that underlie the development and progression of the disease. A focus is given to the role of bioenergetic sources, namely, glucose, lipids, and glutamine sustaining PCa cell survival and growth. Moreover, it is described as the action of oncogenes/tumor suppressors and sex steroid hormones in the metabolic reprogramming of PCa. Finally, the status of PCa treatment based on the inhibition of metabolic pathways is presented. Globally, this review updates the landscape of PCa metabolism, highlighting the critical metabolic alterations that could have a clinical and therapeutic interest.

A Systematic Study of the Impact of Estrogens and Selective Estrogen Receptor Modulators on Prostate Cancer Cell Proliferation

The estrogen signaling pathway has been reported to modulate prostate cancer (PCa) progression through the activity of estrogen receptors α and β (ERα and ERβ). Given that selective estrogen receptor modulators (SERMs) are used to treat breast cancer, ERs have been proposed as attractive therapeutic targets in PCa. However, many inconsistencies regarding the expression of ERs and the efficacy of SERMs for PCa treatment exist, notably due to the use of ERβ antibodies lacking specificity and treatments with high SERM concentrations leading to off-target effects. To end this confusion, our objective was to study the impact of estrogenic and anti-estrogenic ligands in well-studied in vitro PCa models with appropriate controls, dosages, and ER subtype-specific antibodies. When using physiologically relevant concentrations of nine estrogenic/anti-estrogenic compounds, including five SERMs, we observed no significant modulation of PCa cell proliferation. Using RNA-seq and validated antibodies, we demonstrate that these PCa models do not express ERs. In contrast, RNA-seq from PCa samples from patients have detectable expression of ERα. Overall, our study reveals that commonly used PCa models are inappropriate to study ERs and indicate that usage of alternative models is essential to properly assess the roles of the estrogen signaling pathway in PCa.

Translational offsetting as a mode of estrogen receptor α-dependent regulation of gene expression

Estrogen receptor alpha (ERα) activity is associated with increased cancer cell proliferation. Studies aiming to understand the impact of ERα on cancer-associated phenotypes have largely been limited to its transcriptional activity. Herein, we demonstrate that ERα coordinates its transcriptional output with selective modulation of mRNA translation. Importantly, translational perturbations caused by depletion of ERα largely manifest as "translational offsetting" of the transcriptome, whereby amounts of translated mRNAs and corresponding protein levels are maintained constant despite changes in mRNA abundance. Transcripts whose levels, but not polysome association, are reduced following ERα depletion lack features which limit translation efficiency including structured 5'UTRs and miRNA target sites. In contrast, mRNAs induced upon ERα depletion whose polysome association remains unaltered are enriched in codons requiring U34-modified tRNAs for efficient decoding. Consistently, ERα regulates levels of U34-modifying enzymes and thereby controls levels of U34-modified tRNAs. These findings unravel a hitherto unprecedented mechanism of ERα-dependent orchestration of transcriptional and translational programs that may be a pervasive mechanism of proteome maintenance in hormone-dependent cancers.

Association between decreased expression of estrogen receptor alpha, androgen receptor and phosphatase and tensin homolog immunoexpression in the canine prostate

ABSTRACT: Canine prostate gland is a hormonal dependent organ and its imbalance of estrogen and androgen receptor expressions are directly associated with the development of different diseases. Due to the lack of information regarding the behavior of the aforementioned receptors in canine prostate cancer (PC), this study aimed to identify estrogen receptor alpha (ERα), androgen receptor (AR), Ki67 and phosphatase and tensin homolog (PTEN) protein expressions in canine PC by immunohistochemistry. We found nuclear expression of ERα and AR in the epithelial cells of normal canine samples and a loss of protein expression in PC samples. Normal samples showed Ki67 expression in a few basal cells and the PC samples showed the highest mean of positive cells (253.1). Canine prostate cancer showed a high proliferative index, which was associated with independence of hormonal actuation. PTEN showed positive nuclear and cytoplasmic expression in normal canine samples and a loss in PC. Loss of ERα, AR and PTEN indicated that canine PC exhibits the same immunohistochemical phenotype as in human patients with PC resistant to hormonal therapy. Therefore, canine PC should be considered as a model to study human PC resistant to hormonal therapy.

Estrogen Receptor α Is Crucial in Zearalenone-Induced Invasion and Migration of Prostate Cancer Cells

Zearalenone (ZEA), a mycotoxin produced in the genus Fusarium, binds to estrogen receptors (ER) and is therefore regarded as an endocrine disruptor. ZEA has also been found to modulate the proliferation and apoptosis of prostate cancer cells in a dose-dependent manner. This study evaluates whether the effect of a low dose of ZEA (0.1 and 0.001 nM) on the invasion and migration of prostate cancer cell line PC3 is associated with ERs expression. The invasion and migration was evaluated by modified Boyden chamber assay, scratch assay, gelatin zymography, Real Time qPCR (RTqPCR) and Western blot. The involvement of ERs was evaluated with the selective ER antagonists: estrogen receptor α (ERα) antagonist 1,3-bis (4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy) phenol]-1H-pyrazole dihydrochloride (MPP) and estrogen receptor β (ERβ) antagonist 4-[2–phenyl-5,7–bis (trifluoromethyl) pyrazolo [1,5-a]-pyrimidin-3-yl] phenol (PHTPP). ZEA was found to modulate cell motility dependent on estrogen receptors, particularly ERα. Increased cell migration and invasion were associated with increased MMP-2 and MMP-9 activity as well as the up-regulation of the EMT-associated genes vimentin (VIM), zinc finger E-box-binding homeobox 1/2 (ZEB1/2) and transforming growth factor β 1 (TGFβ1). In conclusion, ZEA might modulate the invasiveness of prostate cancer cells dependently on ERα expression.

Estrogen and Androgen Blockade for Advanced Prostate Cancer in the Era of Precision Medicine

Androgen deprivation therapy (ADT) has been widely prescribed for patients with advanced prostate cancer (PC) to control key signaling pathways via androgen receptor (AR) and AR-collaborative transcriptional factors; however, PC gradually acquires a lethal phenotype and results in castration-resistant PC (CRPC) during ADT. Therefore, new therapeutic strategies are required in clinical practice. In addition, ARs; estrogen receptors (ERs; ERα and ERβ); and estrogen-related receptors (ERRs; ERRα, ERRβ, and ERRγ) have been reported to be involved in the development or regulation of PC. Recent investigations have revealed the role of associated molecules, such as KLF5, FOXO1, PDGFA, VEGF-A, WNT5A, TGFβ1, and micro-RNA 135a of PC, via ERs and ERRs. Selective ER modulators (SERMs) have been developed. Recently, estrogen and androgen blockade (EAB) using a combination of toremifene and ADT has been demonstrated to improve biochemical recurrence rate in treatment-naïve bone metastatic PC. In the future, the suitability of ADT alone or EAB for individuals may be evaluated by making clinical decisions on the basis of information obtained from RT-PCR, gene-panel, or liquid biopsy to create a “personalized medicine” or “precision medicine”. In this review, we summarize ER and ERR signaling pathways, molecular diagnosis, and SERMs as candidates for advanced PC treatment.

Estrogens and Their Receptors in Prostate Cancer: Therapeutic Implications

A major challenge in clinical management of prostate cancer (PC) is to limit tumor growth and prevent metastatic spreading. Considerable efforts have been made to discover new compounds for PC therapy and recent years have seen promising progress in this field. Pharmacological approaches have been designed to achieve benefits in PC treatment and avoid the negative side effects resulting from administration of antagonists or agonists or new drugs. Nonetheless, the currently available therapies frequently induce resistance and PC progresses toward castration-resistant forms that can be caused by the androgen receptor reactivation and/or mutations, or derangement of signaling pathways. Preclinical and clinical findings have also shown that other nuclear receptors are frequently altered in PC. In this review, we focus on the role of estradiol/estradiol receptor (ER) axis, which controls PC growth and progression. Selective targeting of ER subtypes (α or β) may be an attractive way to limit the growth and spreading of prostatic cancer cells.

Design, Synthesis, and Evaluation of GLUT Inhibitors

The Warburg effect describes how most cancer cells exhibit higher-than-normal glucose consumption, not only under hypoxic conditions, but also when normal oxygen levels are present. Although glucose transporter 1 (GLUT1) has been found to play a key role in the cellular uptake of glucose, especially in cancer cells, where it is generally overexpressed, it has not been given consideration as a suitable target for the development of anticancer drugs. In this chapter, an example of molecular design and realization of novel GLUT1 inhibitors, including in silico modeling, chemical synthesis, and biological characterization, is provided. This process started with the identification of a focused series of oxime derivatives, originally designed as estrogen receptor (ER) ligands, which were structurally optimized in order to direct their activity towards GLUT1 and to minimize their binding to the ERs, leading to the production of efficient and selective inhibitors of glucose uptake in cancer cells.

Prostate Cancer Risk and DNA Methylation Signatures in Aging Rats following Developmental BPA Exposure: A Dose-Response Analysis

BACKGROUND

Previous studies have uncovered heightened prostatic susceptibility to hormone-induced neoplasia from early-life exposure to low-dose bisphenol A (BPA). However, significant data gaps remain that are essential to address for biological relevance and necessary risk assessment.

OBJECTIVES

A complete BPA dose-response analysis of prostate lesions across multiple prostatic lobes was conducted that included internal BPA dosimetry, progression to adenocarcinoma with aging and mechanistic connections to epigenetically reprogramed genes.

METHODS

Male neonatal Sprague-Dawley rats were briefly exposed to 0.1 to 5,000 μg BPA/kg BW on postnatal days (PND) 1, 3, and 5. Individual prostate lobes plus periurethral prostatic ducts were evaluated at 7 mo or 1 y of age without or with adult testosterone plus estradiol (T+E) to promote carcinogenesis. DNA methylation of five genes was quantified by bisulfite genomic sequencing in d-200 dorsal prostates across BPA doses. Serum free-BPA and BPA-glucuronide were quantitated in sera of individual PND 3 pups collected 1 hr postexposure utilizing ultra-high-pressure tandem mass spectrometry (UHPLC-MS-MS).

RESULTS

The lowest BPA dose initiated maximal hormonal carcinogenesis in lateral prostates despite undetectable free BPA 1 hr postexposure. Further, prostatic intraepithelial neoplasia (PIN) progressed to carcinoma in rats given neonatal low-dose BPA with adult T+E but not in rats given adult T+E alone. The dorsal and ventral lobes and periurethral prostatic ducts exhibited a nonmonotonic dose response with peak PIN, proliferation and apoptotic values at 10–100 μg/kg BW. This was paralleled by nonmonotonic and dose-specific DNA hypomethylation of genes that confer carcinogenic risk, with greatest hypomethylation at the lowest BPA doses.

CONCLUSIONS

Developmental BPA exposures heighten prostate cancer susceptibility in a complex dose- and lobe-specific manner. Importantly, elevated carcinogenic risk is found at doses that yield undetectable serum free BPA. Dose-specific epigenetic modifications of selected genes provide a mechanistic framework that may connect early-life BPA to later-life predisposition to prostate carcinogenesis. https://doi.org/10.1289/EHP1050.

Autoantibodies against oncogenic ERG protein in prostate cancer: potential use in diagnosis and prognosis in a panel with C-MYC, AMACR and HERV-K Gag

Overdiagnosis and overtreatment of prostate cancer (CaP) is attributable to widespread reliance on PSA screening in the US. This has prompted us and others to search for improved biomarkers for CaP, to facilitate early detection and disease stratification. In this regard, autoantibodies (AAbs) against tumor antigens could serve as potential candidates for diagnosis and prognosis of CaP. Towards this, our goals were: i) To investigate whether AAbs against ERG oncoprotein (overexpressed in 25-50% of Caucasian American and African American CaP) are present in the sera of CaP patients; ii) To evaluate an AAb panel to enhance CaP detection. The results using an enzyme-linked immunosorbent assay (ELISA) showed that anti-ERG AAbs are present in a significantly higher proportion in the sera of CaP patients compared to healthy controls (p = 0.0001). Furthermore, a panel of AAbs against ERG, AMACR and human endogenous retrovirus-K Gag successfully differentiated CaP patient sera from healthy controls (AUC = 0.791). These results demonstrate for the first time that anti-ERG AAbs are present in the sera of CaP patients. In addition, the data also suggest that AAbs against ERG together with AMACR and HERV-K Gag may be a useful panel of biomarkers for diagnosis and prognosis of CaP.

WOMEN IN CANCER THEMATIC REVIEW: New roles for nuclear receptors in prostate cancer

Prostate cancer has, for decades, been treated by inhibiting androgen signalling. This is effective in the majority of patients, but inevitably resistance develops and patients progress to life-threatening metastatic disease - hence the quest for new effective therapies for 'castrate-resistant' prostate cancer (CRPC). Studies into what pathways can drive tumour recurrence under these conditions has identified several other nuclear receptor signalling pathways as potential drivers or modulators of CRPC.The nuclear receptors constitute a large (48 members) superfamily of transcription factors sharing a common modular functional structure. Many of them are activated by the binding of small lipophilic molecules, making them potentially druggable. Even those for which no ligand exists or has yet been identified may be tractable to activity modulation by small molecules. Moreover, genomic studies have shown that in models of CRPC, other nuclear receptors can potentially drive similar transcriptional responses to the androgen receptor, while analysis of expression and sequencing databases shows disproportionately high mutation and copy number variation rates among the superfamily. Hence, the nuclear receptor superfamily is of intense interest in the drive to understand how prostate cancer recurs and how we may best treat such recurrent disease. This review aims to provide a snapshot of the current knowledge of the roles of different nuclear receptors in prostate cancer - a rapidly evolving field of research.

Mechanisms of dihydrotestosterone action on resveratrol-induced anti-proliferation in breast cancer cells with different ERα status

Dihydrotestosterone (DHT) has been shown to promote breast cancer growth via different mechanisms. In addition to binding to ERα, the DHT membrane receptor exists on integrin αvβ3. Resveratrol induces p53-dependent apoptosis via plasma membrane integrin αvβ3. Resveratrol and DHT signals are both transduced by activated ERK1/2; however, DHT promotes cell proliferation in cancer cells, whereas resveratrol is pro-apoptotic. In this study, we examined the mechanism by which DHT inhibits resveratrol-induced apoptosis in human ERα positive (MCF-7) and negative (MDA-MB-231) breast cancer cells. DHT inhibited resveratrol-stimulated phosphorylation of Ser-15 of p53 in a concentration-dependent manner. These effects of DHT on resveratrol action were blocked by an ERα antagonist, ICI 182,780, in MCF-7 breast cancer cells. DHT inhibited resveratrol-induced nuclear complex of p53-COX-2 formation which is required p53-dependent apoptosis. ChIP studies of COX-2/p53 binding to DNA and expression of p53-responsive genes indicated that DHT inhibited resveratrol-induced p53-directed transcriptional activity. In addition, DHT did inhibit resveratrol-induced COX-2/p53-dependent gene expression. These results suggest that DHT inhibits p53-dependent apoptosis in breast cancer cells by interfering with nuclear COX-2 accumulation which is essential for stimulation of apoptotic pathways. Thus, the surface receptor sites for resveratrol and DHT are discrete and activate ERK1/2-dependent downstream effects on apoptosis that are distinctive. These studies provide new insights into the antagonizing effects of resveratrol versus DHT, an important step toward better understanding and eventually treating breast cancer. It also indicates the complex pathways by which apoptosis is induced by resveratrol in DHT-depleted and -repleted environments.

The Dual Inhibition of RNA Pol I Transcription and PIM Kinase as a New Therapeutic Approach to Treat Advanced Prostate Cancer

PURPOSE

The MYC oncogene is frequently overexpressed in prostate cancer. Upregulation of ribosome biogenesis and function is characteristic of MYC-driven tumors. In addition, PIM kinases activate MYC signaling and mRNA translation in prostate cancer and cooperate with MYC to accelerate tumorigenesis. Here, we investigate the efficacy of a single and dual approach targeting ribosome biogenesis and function to treat prostate cancer.

EXPERIMENTAL DESIGN

The inhibition of ribosomal RNA (rRNA) synthesis with CX-5461, a potent, selective, and orally bioavailable inhibitor of RNA polymerase I (Pol I) transcription, has been successfully exploited therapeutically but only in models of hematologic malignancy. CX-5461 and CX-6258, a pan-PIM kinase inhibitor, were tested alone and in combination in prostate cancer cell lines, in Hi-MYC- and PTEN-deficient mouse models and in patient-derived xenografts (PDX) of metastatic tissue obtained from a patient with castration-resistant prostate cancer.

RESULTS

CX-5461 inhibited anchorage-independent growth and induced cell-cycle arrest in prostate cancer cell lines at nanomolar concentrations. Oral administration of 50 mg/kg CX-5461 induced TP53 expression and activity and reduced proliferation (MKI67) and invasion (loss of ductal actin) in Hi-MYC tumors, but not in PTEN-null (low MYC) tumors. While 100 mg/kg CX-6258 showed limited effect alone, its combination with CX-5461 further suppressed proliferation and dramatically reduced large invasive lesions in both models. This rational combination strategy significantly inhibited proliferation and induced cell death in PDX of prostate cancer.

CONCLUSIONS

Our results demonstrate preclinical efficacy of targeting the ribosome at multiple levels and provide a new approach for the treatment of prostate cancer. Clin Cancer Res; 22(22); 5539-52. ©2016 AACR.

In touch with your feminine side: how oestrogen metabolism impacts prostate cancer

Prostate cancer is the primary cancer in males, with increasing global incidence rates making this malignancy a significant healthcare burden. Androgens not only promote normal prostate maturity but also influence the development and progression of prostate cancer. Intriguingly, evidence now suggests endogenous and exogenous oestrogens, in the form of phytoestrogens, may be equally as relevant as androgens in prostate cancer growth. The prostate gland has the molecular mechanisms, catalysed by steroid sulphatase (STS), to unconjugate and utilise circulating oestrogens. Furthermore, prostate tissue also expresses enzymes essential for local oestrogen metabolism, including aromatase (CYP19A1) and 3β- and 17β-hydroxysteroid dehydrogenases. Increased expression of these enzymes in malignant prostate tissue compared with normal prostate indicates that oestrogen synthesis is favoured in malignancy and thus may influence tumour progression. In contrast to previous reviews, here we comprehensively explore the epidemiological and scientific evidence on how oestrogens impact prostate cancer, particularly focusing on pre-receptor oestrogen metabolism and subsequent molecular action. We analyse how molecular mechanisms and metabolic pathways involved in androgen and oestrogen synthesis intertwine to alter prostate tissue. Furthermore, we speculate on whether oestrogen receptor status in the prostate affects progression of this malignancy.

Oestrogens and oestrogen receptors in prostate cancer

The role of androgens in prostate cancer is obvious due to the fact that androgen signalling is the main regulator of prostate growth and function. Androgen deprivation therapy is a mainstay treatment for advanced prostate cancer. However, prostate cancer often becomes androgen-independent, which in consequence leads to lethal and incurable disease. In addition, oestrogens play a crucial role in prostate cancer, especially in elder men in whom the overall ratio of oestrogens to androgens is increasing. This review summarizes the current knowledge on molecular mechanisms through which oestrogens are involved in prostate cancer development. We focused on commonly alternated molecular signalling pathways contributing to tumourgenesis in prostate cancer.

Myc-dependent purine biosynthesis affects nucleolar stress and therapy response in prostate cancer

The androgen receptor is a key transcription factor contributing to the development of all stages of prostate cancer (PCa). In addition, other transcription factors have been associated with poor prognosis in PCa, amongst which c-Myc (MYC) is a well-established oncogene in many other cancers. We have previously reported that the AR promotes glycolysis and anabolic metabolism; many of these metabolic pathways are also MYC-regulated in other cancers. In this study, we report that in PCa cells de novo purine biosynthesis and the subsequent conversion to XMP is tightly regulated by MYC and independent of AR activity. We characterized two enzymes, PAICS and IMPDH2, within the pathway as PCa biomarkers in tissue samples and report increased efficacy of established anti-androgens in combination with a clinically approved IMPDH inhibitor, mycophenolic acid (MPA). Treatment with MPA led to a significant reduction in cellular guanosine triphosphate (GTP) levels accompanied by nucleolar stress and p53 stabilization. In conclusion, targeting purine biosynthesis provides an opportunity to perturb PCa metabolism and enhance tumour suppressive stress responses.

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.

Network analysis of an in vitro model of androgen-resistance in prostate cancer

BACKGROUND

The development of androgen resistance is a major limitation to androgen deprivation treatment in prostate cancer. We have developed an in vitro model of androgen-resistance to characterise molecular changes occurring as androgen resistance evolves over time. Our aim is to understand biological network profiles of transcriptomic changes occurring during the transition to androgen-resistance and to validate these changes between our in vitro model and clinical datasets (paired samples before and after androgen-deprivation therapy of patients with advanced prostate cancer).

METHODS

We established an androgen-independent subline from LNCaP cells by prolonged exposure to androgen-deprivation. We examined phenotypic profiles and performed RNA-sequencing. The reads generated were compared to human clinical samples and were analysed using differential expression, pathway analysis and protein-protein interaction networks.

RESULTS

After 24 weeks of androgen-deprivation, LNCaP cells had increased proliferative and invasive behaviour compared to parental LNCaP, and its growth was no longer responsive to androgen. We identified key genes and pathways that overlap between our cell line and clinical RNA sequencing datasets and analysed the overlapping protein-protein interaction network that shared the same pattern of behaviour in both datasets. Mechanisms bypassing androgen receptor signalling pathways are significantly enriched. Several steroid hormone receptors are differentially expressed in both datasets. In particular, the progesterone receptor is significantly differentially expressed and is part of the interaction network disrupted in both datasets. Other signalling pathways commonly altered in prostate cancer, MAPK and PI3K-Akt pathways, are significantly enriched in both datasets.

CONCLUSIONS

The overlap between the human and cell-line differential expression profiles and protein networks was statistically significant showing that the cell-line model reproduces molecular patterns observed in clinical castrate resistant prostate cancer samples, making this cell line a useful tool in understanding castrate resistant prostate cancer. Pathway analysis revealed similar patterns of enriched pathways from differentially expressed genes of both human clinical and cell line datasets. Our analysis revealed several potential mechanisms and network interactions, including cooperative behaviours of other nuclear receptors, in particular the subfamily of steroid hormone receptors such as PGR and alteration to gene expression in both the MAPK and PI3K-Akt signalling pathways.

Toremifene, a selective estrogen receptor modulator, significantly improved biochemical recurrence in bone metastatic prostate cancer: a randomized controlled phase II a trial

BACKGROUNDS

Durability of androgen-deprivation therapy (ADT) for prostate cancer (PC) is limited. Additional selective estrogen receptor modulators (SERMs) may prolong the durability of ADT, because androgen and estrogen signaling drive PC progression.

METHODS

Men with treatment-naïve bone metastatic PC were randomly assigned in 1:1:1 fashion to receive ADT, toremifene 60 mg plus ADT (TOPADT), or raloxifene 60 mg plus ADT (RAPADT). The primary endpoint was the biochemical recurrence (BCR) rate, and secondary endpoints were changes of scores of the visual analogue scale (VAS) and the functional assessment of cancer therapy (FACT).

RESULTS

A total of 15 men, 5 each, were allocated to one of the three treatment arms. The basal serum prostate-specific antigen (PSA) level was 198 ng/mL (median, range; 30-8428). Bone metastases were graded as 1 (n = 11), 2 (n = 3), and 3 (n = 1) by the extent of disease. During the median follow-up period of 1370 days (range; 431-1983), BCR occurred in 3, 0 and 2 men in ADT, TOPADT and RAPADT group, respectively. The 5-year BCR-free rate was 30, 100 and 53 %, in ADT, TOPADT and RAPADT group, respectively (p = 0.04, ADT v.s. TOPADT, p = 0.48, ADT v.s. RAPADT and p = 0.12, TOPADT v.s. RAPADT). Scores of VAS improved in all groups and remained stable throughout the study. This analysis is limited as a preliminary result in a single center.

CONCLUSIONS

Toremifene with conventional ADT significantly improved the BCR rate in treatment-naïve bone metastatic PC. Further clinical trials are warranted to confirm the promising clinical efficacy of this combination therapy.

TRIAL REGISTRATION

The protocol was registered at the University Hospital Medical Information Network ( UMIN ID;0,000,064,000 ) in Sep 25, 2011.

Metformin Attenuates Testosterone-Induced Prostatic Hyperplasia in Rats: A Pharmacological Perspective

Benign prostatic hyperplasia (BPH) is uncontrolled proliferation of prostate tissue. Metformin, a widely prescribed anti-diabetic agent, possesses anticancer activity through induction of apoptotic signaling and cell cycle arrest. This study aimed to investigate the protective effect of metformin against experimentally-induced BPH in rats. Treatment with 500 and 1000 mg/kg metformin orally for 14 days significantly inhibited testosterone-mediated increase in the prostate weight & prostate index (prostate weight/body weight [mg/g]) and attenuated the pathological alterations induced by testosterone. Mechanistically, metformin significantly protected against testosterone-induced elevation of estrogen receptor-α (ER-α) and decrease of estrogen receptor-β (ER-β) expression, with no significant effect of androgen receptor (AR) and 5α-reductase expression. It decreased mRNA expression of IGF-1 and IGF-1R and protein expression ratio of pAkt/total Akt induced by testosterone. Furthermore, it significantly ameliorated testosterone–induced reduction of mRNA expression Bax/Bcl-2 ratio, P21 and phosphatase and tensin homolog (PTEN) and AMPK [PT-172] activity. In conclusion, these findings elucidate the effectiveness of metformin in preventing testosterone-induced BPH in rats. These results could be attributed, at least partly, to its ability to enhance expression ratio of ER-β/ER-α, decrease IGF-1, IGF-1R and pAkt expressions, increase P21, PTEN, Bax/Bcl-2 expressions and activate AMPK with a subsequent inhibition of prostate proliferation.