Blockade of testicular and adrenal androgens in prostate cancer treatment

Anti-Müllerian hormone: a novel biomarker for aggressive prostate cancer? Emerging evidence from a prospective study of radical prostatectomies

PURPOSE

Prostate cancer patients are a heterogeneous group as regards the aggressiveness of the disease. The relationship of steroid hormones with the aggressiveness of prostate cancer is unclear. It is known that the anti-Müllerian hormone (AMH) inhibits prostate cancer cell lines in vitro. The aim of this study is to investigate the relationship of AMH and steroid hormones with the aggressiveness of prostate cancer.

METHODS

This was a prospective study of consecutive radical prostatectomy patients. We measured the following hormones: total testosterone, sex hormone-binding globulin, albumin, luteinizing hormone, follicle-stimulating hormone, estradiol, dehydroepiandrosterone sulfate, androstenedione, and AMH. The minimum follow-up after radical prostatectomy was 5 years. For the aggressiveness of prostate cancer, we considered the following three variables: post-operative Gleason score (GS) ≥ 8, TNM pΤ3 disease, and prostate-specific antigen (PSA) biochemical recurrence (BCR).

RESULTS

In total, 91 patients were enrolled. The mean age and PSA were 64.8 years and 9.3 ng/dl, respectively. The median post-operative GS was 7. Low AMH blood levels were correlated with higher post-operative GS (p = 0.001), as well as with PSA BCR (p = 0.043). With pT3 disease, only albumin was (negatively) correlated (p = 0.008). ROC analysis showed that AMH is a good predictor of BCR (AUC 0.646, 95% CI 0.510-0.782, p = 0.043); a cutoff value of 3.06 ng/dl had a positive prognostic value of 71.4% and a negative prognostic value of 63.3% for BCR. Cox regression analysis showed that AMH is a statistically significant and independent prognostic marker for BCR (p = 0.013). More precisely, for every 1 ng/ml of AMH rise, the probability for PSA BCR decreases by 20.8% (HR = 0.792). Moreover, in Kaplan-Meier analysis, disease-free survival is more probable in patients with AMΗ ≥ 3.06 ng/ml (p = 0.004).

CONCLUSIONS

Low AMH blood levels were correlated with aggressive prostate cancer in this radical prostatectomy cohort of patients. Therefore, AMH could be a prognostic biomarker for the aggressiveness of the disease.

A comprehensive review on lipid nanocarrier systems for cancer treatment: fabrication, future prospects and clinical trials

Over the last few decades, cancer has been considered a clinical challenge, being among the leading causes of mortality all over the world. Although many treatment approaches have been developed for cancer, chemotherapy is still the most utilized in the clinical setting. However, the available chemotherapeutics-based treatments have several caveats including their lack of specificity, adverse effects as well as cancer relapse and metastasis which mainly explains the low survival rate of patients. Lipid nanoparticles (LNPs) have been utilized as promising nanocarrier systems for chemotherapeutics to overcome the challenges of the currently applied therapeutic strategies for cancer treatment. Loading chemotherapeutic agent(s) into LNPs improves drug delivery at different aspects including specific targeting of tumours, and enhancing the bioavailability of drugs at the tumour site through selective release of their payload, thus reducing their undesired side effects on healthy cells. This review article delineates an overview of the clinical challenges in many cancer treatments as well as depicts the role of LNPs in achieving optimal therapeutic outcomes. Moreover, the review contains a comprehensive description of the many LNPs categories used as nanocarriers in cancer treatment to date, as well as the potential of LNPs for future applications in other areas of medicine and research.

Obesity-induced thymic involution and cancer risk

Declining thymic functions associated either with old age (i.e., age-related thymic involution), or with acute involution as a result of stress, infectious disease, or cytoreductive therapies (e.g., chemotherapy/radiotherapy), have been associated with cancer development. A key mechanism underlying such increased cancer risk is the thymus-dependent debilitation of adaptive immunity, which is responsible for orchestrating immunoediting mechanisms and tumor immune surveillance. In the past few years, a blooming set of evidence has intriguingly linked obesity with cancer development and progression. The majority of such studies has focused on obesity-driven chronic inflammation, steroid/sex hormone and adipokine production, and hyperinsulinemia, as principal factors affecting the tumor microenvironment and driving the development of primary malignancy. However, experimental observations about the negative impact of obesity on T cell development and maturation have existed for more than half a century. Here, we critically discuss the molecular and cellular mechanisms of obesity-driven thymic involution as a previously underrepresented intermediary pathology leading to cancer development and progression. This knowledge could be especially relevant in the context of childhood obesity, because impaired thymic function in young individuals leads to immune system abnormalities, and predisposes to various pediatric cancers. A thorough understanding behind the molecular and cellular circuitries governing obesity-induced thymic involution could therefore help towards the rationalized development of targeted thymic regeneration strategies for obese individuals at high risk of cancer development.

Preclinical models of prostate cancer - modelling androgen dependency and castration resistance in vitro, ex vivo and in vivo

Prostate cancer is well known to be dependent on the androgen receptor (AR) for growth and survival. Thus, AR is the main pharmacological target to treat this disease. However, after an initially positive response to AR-targeting therapies, prostate cancer will eventually evolve to castration-resistant prostate cancer, which is often lethal. Tumour growth was initially thought to become androgen-independent following treatments; however, results from molecular studies have shown that most resistance mechanisms involve the reactivation of AR. Consequently, tumour cells become resistant to castration - the blockade of testicular androgens - and not independent of AR per se. However, confusion still remains on how to properly define preclinical models of prostate cancer, including cell lines. Most cell lines were isolated from patients for cell culture after evolution of the tumour to castration-resistant prostate cancer, but not all of these cell lines are described as castration resistant. Moreover, castration refers to the blockade of testosterone production by the testes; thus, even the concept of "castration" in vitro is questionable. To ensure maximal transfer of knowledge from scientific research to the clinic, understanding the limitations and advantages of preclinical models, as well as how these models recapitulate cancer cell androgen dependency and can be used to study castration resistance mechanisms, is essential.

UGT2B28 accelerates prostate cancer progression through stabilization of the endocytic adaptor protein HIP1 regulating AR and EGFR pathways

The androgen inactivating UGT2B28 pathway emerges as a predictor of progression in prostate cancer (PCa). However, the clinical significance of UGT2B28 tumoral expression and its contribution to PCa progression remain unclear. Using the Canadian Prostate Cancer Biomarker Network biobank (CPCBN; n = 1512), we analyzed UGT2B28 tumor expression in relation to clinical outcomes in men with localized PCa. UGT2B28 was overexpressed in tumors compared to paired normal adjacent prostatic tissue and was associated with inferior outcomes. Functional analyses indicated that UGT2B28 promoted cell proliferation, and its expression was regulated by the androgen receptor (AR)/ARv7. Mechanistically, UGT2B28 was shown to be a protein partner of the endocytic adaptor protein huntingtin-interacting protein 1 (HIP1), increasing its stability and priming AR/epidermal growth factor receptor (EGFR) pathways, leading to ERK1/2 activation triggering cell proliferation and epithelial-to-mesenchymal transition (EMT). HIP1 knockdown in UGT2B28 positive cells, and dual pharmacological targeting of AR and EGFR pathways, abolished cell proliferative advantages conferred by UGT2B28. In conclusion, UGT2B28 is a prognosticator of progression in localized PCa, regulates both AR and EGFR oncogenic signaling pathways via HIP1, and therefore can be therapeutically targeted by using combination of existing AR/EGFR inhibitors.

Allopregnanolone: Metabolism, Mechanisms of Action, and Its Role in Cancer

Allopregnanolone (3α-THP) has been one of the most studied progesterone metabolites for decades. 3α-THP and its synthetic analogs have been evaluated as therapeutic agents for pathologies such as anxiety and depression. Enzymes involved in the metabolism of 3α-THP are expressed in classical and nonclassical steroidogenic tissues. Additionally, due to its chemical structure, 3α-THP presents high affinity and agonist activity for nuclear and membrane receptors of neuroactive steroids and neurotransmitters, such as the Pregnane X Receptor (PXR), membrane progesterone receptors (mPR) and the ionotropic GABA_A receptor, among others. 3α-THP has immunomodulator and antiapoptotic properties. It also induces cell proliferation and migration, all of which are critical processes involved in cancer progression. Recently the study of 3α-THP has indicated that low physiological concentrations of this metabolite induce the progression of several types of cancer, such as breast, ovarian, and glioblastoma, while high concentrations inhibit it. In this review, we explore current knowledge on the metabolism and mechanisms of action of 3α-THP in normal and tumor cells.

Testosterone level in seminal vesicle fluid is a better indicator of erectile function than serum testosterone in patients with prostate cancer

OBJECTIVES

Semen comprises prostatic fluid and seminal vesicle fluid, and seminal vesicle fluid contains various factors such as prostaglandin E2 (PGE2), zinc, and testosterone, which play important roles in sperm motility. It is not known whether these factors affect erectile function. In this study, we investigated factors in seminal vesicle fluid that may affect erectile function.

METHODS

After receiving institutional review board approval, we collected seminal vesicle fluid samples from 134 Japanese patients with localized prostate cancer who underwent robot-assisted radical prostatectomy. We examined the relationship between the results of the Sexual Health Inventory for Men (SHIM), erection hardness score, an original questionnaire on the presence or absence of sexual desire, and concentrations of several factors in seminal vesicle fluid (testosterone, PGE2, transforming growth factor β1, and 8-hydroxy-2-deoxyguanosine), as well as the serum testosterone level.

RESULTS

Median participant age was 67 (range 51-77) years. Median concentrations were as follows: seminal vesicle testosterone 1.85 (range 0.17-4.32) ng/ml and serum testosterone 4.60 (range 1.75-10.82) ng/ml. When the SHIM score was divided into two groups, seminal vesicle testosterone concentration was significantly increased (p = 0.002) in participants with a SHIM score ≥17, and no significant difference was observed in serum testosterone levels (p = 0.661). Multivariate analysis revealed that seminal vesicle testosterone was significantly correlated with the SHIM score (≥17 vs. <17; odds ratio 2.137, 95% confidence interval 1.148-3.978, p = 0.016).

CONCLUSIONS

Testosterone levels in seminal vesicle fluid can reflect erectile function in patients with prostate cancer, suggesting that seminal vesicle testosterone is very important for male erectile function.

Mutual Shaping of Circadian Body-Wide Synchronization by the Suprachiasmatic Nucleus and Circulating Steroids

Background

Steroids are lipid hormones that reach bodily tissues through the systemic circulation, and play a major role in reproduction, metabolism, and homeostasis. All of these functions and steroids themselves are under the regulation of the circadian timing system (CTS) and its cellular/molecular underpinnings. In health, cells throughout the body coordinate their daily activities to optimize responses to signals from the CTS and steroids. Misalignment of responses to these signals produces dysfunction and underlies many pathologies.

Questions Addressed

To explore relationships between the CTS and circulating steroids, we examine the brain clock located in the suprachiasmatic nucleus (SCN), the daily fluctuations in plasma steroids, the mechanisms producing regularly recurring fluctuations, and the actions of steroids on their receptors within the SCN. The goal is to understand the relationship between temporal control of steroid secretion and how rhythmic changes in steroids impact the SCN, which in turn modulate behavior and physiology.

Evidence Surveyed

The CTS is a multi-level organization producing recurrent feedback loops that operate on several time scales. We review the evidence showing that the CTS modulates the timing of secretions from the level of the hypothalamus to the steroidogenic gonadal and adrenal glands, and at specific sites within steroidogenic pathways. The SCN determines the timing of steroid hormones that then act on their cognate receptors within the brain clock. In addition, some compartments of the body-wide CTS are impacted by signals derived from food, stress, exercise etc. These in turn act on steroidogenesis to either align or misalign CTS oscillators. Finally this review provides a comprehensive exploration of the broad contribution of steroid receptors in the SCN and how these receptors in turn impact peripheral responses.

Conclusion

The hypothesis emerging from the recognition of steroid receptors in the SCN is that mutual shaping of responses occurs between the brain clock and fluctuating plasma steroid levels.

Advances in stem cell research for the treatment of primary hypogonadism

In Leydig cell dysfunction, cells respond weakly to stimulation by pituitary luteinizing hormone, and, therefore, produce less testosterone, leading to primary hypogonadism. The most widely used treatment for primary hypogonadism is testosterone replacement therapy (TRT). However, TRT causes infertility and has been associated with other adverse effects, such as causing erythrocytosis and gynaecomastia, worsening obstructive sleep apnoea and increasing cardiovascular morbidity and mortality risks. Stem-cell-based therapy that re-establishes testosterone-producing cell lineages in the body has, therefore, become a promising prospect for treating primary hypogonadism. Over the past two decades, substantial advances have been made in the identification of Leydig cell sources for use in transplantation surgery, including the artificial induction of Leydig-like cells from different types of stem cells, for example, stem Leydig cells, mesenchymal stem cells, and pluripotent stem cells (PSCs). PSC-derived Leydig-like cells have already provided a powerful in vitro model to study the molecular mechanisms underlying Leydig cell differentiation and could be used to treat men with primary hypogonadism in a more specific and personalized approach.

Mechanistic targets for BPH and prostate cancer-a review

All men, almost, suffer from prostatic disorders in average life expectancy. In the year of 1950s, the first autopsy of prostate gland discovered the link between Benign prostatic hyperplasia (BPH) and Prostate Cancer (PCa). After that, many histology, biochemistry, epidemiology studies explained the association and associated risk factor for the same. From the various scientific evidence, it is proved that both diseases share some common transcription factors and signalling pathways. Still, BPH cannot be considered as the first step of PCa progression. To define, the relationship between both of the diseases, a well-defined large epidemiological study is needed. Along with androgen signalling, imbalanced apoptosis, oxidative stress, and microbial infection also crucial factors that significantly affect the pathogenesis of BPH. Various signalling pathways are involved in the progression of BPH. Androgen signalling is the driving force for the progress of PCa. In PCa androgen signalling is upregulated as compared to a healthy prostate. Some dominant Androgen-regulated genes and their functions have been discussed in this work.

Tracing steroidogenesis in prostate biopsy samples to unveil prostate tissue androgen metabolism characteristics and potential clinical application

Androgens are essential for prostate cancer development. However, steroidogenesis has mainly been investigated in a limited number of prostate cancer cell lines, leading to varied conclusions and elusive clinical significance. Here, we established an ex vivo research platform with fresh biopsy samples transiently cultured with tritium- labelled androgens to trace steroidogenesis in prostate tissues and investigate its potential clinical application. DHEA was confirmed as the major precursor for androgen synthesis in the prostate. Significant amounts of oxidized DHEA and 5α-androstanedione were generated from DHEA in prostate biopsy samples. Prostatic steroidogenesis was independent of other clinical factors. Furthermore, prostatic steroidogenesis was suppressed after androgen deprivation therapy but increased upon treatment resistance, indicating that prostatic steroidogenesis was affected by clinical treatments. Overall, we provide an accessible research platform to characterize steroidogenesis in prostate tissue and indicate the correlation between prostatic steroidogenesis and disease progression.

Adrenal androgens, adrenarche, and zona reticularis: A human affair?

In humans, reticularis cells of the adrenal cortex fuel the production of androgen steroids, constituting the driver of numerous morphological changes during childhood. These steps are considered a precocious stage of sexual maturation and are grouped under the term "adrenarche". This review describes the molecular and enzymatic characteristics of the zona reticularis, along with the possible signals and mechanisms that control its emergence and the associated clinical features. We investigate the differences between species and discuss new studies such as genetic lineage tracing and transcriptomic analysis, highlighting the rodent inner cortex's cellular and molecular heterogeneity. The recent development and characterization of mouse models deficient for Prkar1a presenting with adrenocortical reticularis-like features prompt us to review our vision of the mouse adrenal gland maturation. We expect these new insights will help increase our understanding of the adrenarche process and the pathologies associated with its deregulation.

Estetrol Cotreatment of Androgen Deprivation Therapy in Infiltrating or Metastatic, Castration-sensitive Prostate Cancer: A Randomized, Double-blind, Phase II Trial (PCombi)

Background

Androgen deprivation therapy (ADT) for prostate cancer with luteinizing hormone-releasing hormone (LHRH) agonists can be improved.

Objective

To assess safety, the frequency and severity of hot flushes (HFs), bone health, and antitumor effects of high-dose estetrol (HDE4) when combined with ADT.

Design, setting and participants

A phase II, double-blind, randomized, placebo-controlled study was conducted in advanced prostate cancer patients requiring ADT (the PCombi study).

Intervention

Patients receiving LHRH agonist treatment were randomized 2:1 to 40 mg HDE4 (n = 41) or placebo (n = 21) cotreatment for 24 wk.

Outcome measurements and statistical analysis

Coprimary endpoints were frequency/severity of HFs and levels of total and free testosterone (T). Secondary endpoints included assessments of bone metabolism (osteocalcin and type I collagen telopeptide [CTX1]), prostate-specific antigen (PSA), and follicle-stimulating hormone (FSH). Efficacy analysis was based on the selected per-protocol (PP) population.

Results and limitations

Of 62 patients included in the study, 57 were suitable for a PP analysis (37 HDE4; 20 placebo). No E4-related serious cardiovascular adverse events occurred at 24 wk. Weekly HFs were reported by 13.5% of patients with HDE4 and 60.0% with placebo (p < 0.001). Daily HFs occurred in 5.9% versus 55%. Bone turnover parameters decreased significantly with HDE4 (p < 0.0001). Total and free T decreased earlier (p < 0.05), and free T was suppressed further (p < 0.05). PSA suppression was more profound and earlier (p < 0.005). FSH levels were suppressed by 98% versus 57% (p < 0.0001). Estrogenic side effects were nipple sensitivity (34%) and gynecomastia (17%).

Conclusions

HDE4 cotreatment of ADT patients with advanced prostate cancer was well tolerated, and no treatment-related cardiovascular adverse events were observed at 24 wk. HFs and bone turnover were substantially reduced. Suppression of free T, PSA, and FSH was more rapid and profound, suggesting enhanced disease control by HDE4 cotreatment. Larger and longer-lasting studies are needed to confirm the results of the study reported here.

Patient summary

Cotreatment of androgen deprivation therapy with high-dose estetrol in advanced prostate cancer patients results in fewer occurrences of hot flushes, bone protection, and other antitumor benefits. Nipple sensitivity and gynecomastia may occur as side effects.

ACSS3 represses prostate cancer progression through downregulating lipid droplet-associated protein PLIN3

Current endocrine therapy for prostate cancer (PCa) mainly inhibits androgen/androgen receptor (AR) signaling. However, due to increased intratumoural androgen synthesis and AR variation, PCa progresses to castration-resistant prostate cancer (CRPC), which ultimately becomes resistant to endocrine therapy. A search for new therapeutic perspectives is urgently needed. Methods: By screening lipid metabolism-related gene sets and bioinformatics analysis in prostate cancer database, we identified the key lipid metabolism-related genes in PCa. Bisulfite genomic Sequence Polymerase Chain Reaction (PCR) (BSP) and Methylation-Specific Polymerase Chain Reaction (PCR) (MSP) were preformed to detect the promoter methylation of ACSS3. Gene expression was analyzed by qRT-PCR, Western blotting, IHC and co-IP. The function of ACSS3 in PCa was measured by CCK-8, Transwell assays. LC/MS, Oil Red O assays and TG and cholesterol measurement assays were to detect the levels of TG and cholesterol in cells. Resistance to Enzalutamide in C4-2 ENZR cells was examined in a xenograft tumorigenesis model in vivo. Results: We found that acyl-CoA synthetase short chain family member 3 (ACSS3) was downregulated and predicted a poor prognosis in PCa. Loss of ACSS3 expression was due to gene promoter methylation. Restoration of ACSS3 expression in PCa cells significantly reduced LD deposits, thus promoting apoptosis by increasing endoplasmic reticulum (ER) stress, and decreasing de novo intratumoral androgen synthesis, inhibiting CRPC progression and reversing Enzalutamide resistance. Mechanistic investigations demonstrated that ACSS3 reduced LD deposits by regulating the stability of the LD coat protein perilipin 3 (PLIN3). Conclusions: Our study demonstrated that ACSS3 represses prostate cancer progression through downregulating lipid droplet-associated protein PLIN3.

Radiopharmaceuticals for Bone Metastases

As a single organ distributed diffusely throughout the body, bones represent both a unique challenge and unique opportunity for the treatment of symptomatic metastatic disease. While the multifocality of bone metastases often prevents effective complete treatment with focal radiotherapy, the similar pathophysiology of these diffuse sites of disease opens the door to targeted systemic therapy. The relatively rapid dose fall-off from beta- or alpha-emitting particles, if correctly and reliably targeted to osseous metastases, might reduce tumor burden and enhance pain control or improve survival. Radioisotopes have thus been studied keenly with the first generation of primarily beta-emitting radioisotopes, strontium-89 and samarium-153, which reached early FDA approval based on successful endpoints of pain control. More recently, an alpha-emitting therapy, radium-223, has demonstrated a successful endpoint of improved overall survival in patients with a burden of symptomatic, metastatic castrate-resistant prostate cancer (mCRPC) confined to the bones. With this discovery, an additional survival-improving tool beyond systemic and hormonal agents was added to the treatment arsenal for mCRPC for suitable candidates. With an improved understanding of the optimization of hormonal and systemic therapies in the context of mCRPC, there is lingering uncertainty regarding the safety and efficacy of combinatorial use of alpha and beta-emitting therapies with the current generation of systemic agents. In this narrative review, we will highlight the current understanding of the relative utility and clinical paradigms involving alpha- and beta-emitting radioisotopes. We discuss fundamental mechanisms for antineoplastic activity, initial clinical trials validating their use, the use of concurrent antiresorptive therapies to provide bone protection, and ongoing clinical trials targeted at best utilization of these agents in the broader context of mCRPC treatment.

A Time Scales Approach for Modeling Intermittent Hormone Therapy for Prostate Cancer

Prostate cancer is a common cancer among males in the USA and is often treated by intermittent androgen deprivation therapy. This therapy requires a patient to alternate between periods of androgen suppression treatment and no treatment. Prostate-specific antigen levels are used to track relative changes in tumor volume of prostate cancer patients undergoing intermittent androgen deprivation therapy. During this therapy, there is a pause between treatment cycles. Traditionally, continuous ordinary differential equations are used to estimate prostate-specific antigen levels. In this paper, we use dynamic equations to estimate prostate-specific antigen levels and construct a novel time scale model to account for both continuous and discrete time simultaneously. This allows us to account for breaks between treatment cycles. Using empirical data sets of prostate-specific antigen levels, a known bio-marker of prostate cancer, across multiple patients, we fit our model and use least squares to estimate two parameter values. We then compare our model to the data and find a resemblance on treatment intervals similar to our time scale.

Therapeutic targeting of the androgen receptor (AR) and AR variants in prostate cancer

Prostate cancer (PCa) accounted for over 300 000 deaths world-wide in 2018. Most of the PCa deaths occurred due to the aggressive castration-resistant PCa (CRPC). Since the androgen receptor (AR) and its ligands contribute to the continued growth of androgen-dependent PCa (ADPCa) and CRPC, AR has become a well-characterized and pivotal therapeutic-target. Although AR signaling was identified as therapeutic-target in PCa over five-decades ago, there remains several practical issues such as lack of antagonist-bound AR crystal structure, stabilization of the AR in the presence of agonists due to N-terminus and C-terminus interaction, unfavorable large-molecule accommodation of the ligand-binding domain (LBD), and generation of AR splice variants that lack the LBD that impede the discovery of highly potent fail-safe drugs. This review summarizes the AR-signaling pathway targeted therapeutics currently used in PCa and the approaches that could be used in future AR-targeted drug development of potent next-generation molecules. The review also outlines the discovery of molecules that bind to domains other than the LBD and those that inhibit both the full length and splice variant of ARs.

Formation of 5α-dihydrotestosterone from 5α-androstane-3α,17β-diol in prostate cancer LAPC-4 cells - Identifying inhibitors of non-classical pathways producing the most potent androgen

5α-Dihydrotestosterone (5α-DHT) possesses a great affinity for the androgen receptor (AR), and its binding to AR promotes the proliferation of prostate cancer (PC) cells in androgen-dependent PC. Primarily synthesized from testosterone (T) in testis, 5α-DHT could also be produced from 5α-androstane-3α,17β-diol (3α-diol), an almost inactive androgen, following non-classical pathways. We reported the chemical synthesis of non-commercially available [4-¹⁴C]-3α-diol from [4-¹⁴C]-T, and the development of a biological assay to identify inhibitors of the 5α-DHT formation from radiolabeled 3α-diol in LAPC-4 cell PC model. We measured the inhibitory potency of 5α-androstane derivatives against the formation of 5α-DHT, and inhibition curves were obtained for the most potent compounds (IC₅₀ = 1.2-14.1 μM). The most potent inhibitor 25 (IC₅₀ = 1.2 μM) possesses a 4-(4-CF₃-3-CH₃O-benzyl)piperazinyl methyl side chain at C3β and 17β-OH/17α-CCH functionalities at C17 of a 5α-androstane core.

New Opportunities for Targeting the Androgen Receptor in Prostate Cancer

Recent genomic analyses of metastatic prostate cancer have provided important insight into adaptive changes in androgen receptor (AR) signaling that underpin resistance to androgen deprivation therapies. Novel strategies are required to circumvent these AR-mediated resistance mechanisms and thereby improve prostate cancer survival. In this review, we present a summary of AR structure and function and discuss mechanisms of AR-mediated therapy resistance that represent important areas of focus for the development of new therapies.

Loss of androgen receptor signaling in prostate cancer-associated fibroblasts (CAFs) promotes CCL2- and CXCL8-mediated cancer cell migration

Fibroblasts are abundantly present in the prostate tumor microenvironment (TME), including cancer‐associated fibroblasts (CAFs) which play a key role in cancer development. Androgen receptor (AR) signaling is the main driver of prostate cancer (PCa) progression, and stromal cells in the TME also express AR. High‐grade tumor and poor clinical outcome are associated with low AR expression in the TME, which suggests a protective role of AR signaling in the stroma against PCa development. However, the mechanism of this relation is not clear. In this study, we isolated AR‐expressing CAF‐like cells. Testosterone (R1881) exposure did not affect CAF‐like cell morphology, proliferation, or motility. PCa cell growth was not affected by culturing in medium from R1881‐exposed CAF‐like cells; however, migration of PCa cells was inhibited. AR chromatin immune precipitation sequencing (ChIP‐seq) was performed and motif search suggested that AR in CAF‐like cells bound the chromatin through AP‐1‐elements upon R1881 exposure, inducing enhancer‐mediated AR chromatin interactions. The vast majority of chromatin binding sites in CAF‐like cells were unique and not shared with AR sites observed in PCa cell lines or tumors. AR signaling in CAF‐like cells decreased expression of multiple cytokines; most notably CCL2 and CXCL8 and both cytokines increased migration of PCa cells. These results suggest direct paracrine regulation of PCa cell migration by CAFs through AR signaling.

Mechanisms of Action of Dehydroepiandrosterone

Dehydroepiandrosterone (3β-hydroxy-5-androsten-17-one, DHEA) and its sulfated metabolite DHEA-S are the most abundant steroids in circulation and decline with age. Rodent studies have shown that DHEA has a wide variety of effects on liver, kidney, adipose, reproductive tissues, and central nervous system/neuronal function. The mechanisms by which DHEA and DHEA-S impart their physiological effects may be direct actions on plasma membrane receptors, including a DHEA-specific, G-protein-coupled receptor in endothelial cells; various neuroreceptors, e.g., aminobutyric-acid-type A, N-methyl-d-aspartate (NMDA), and sigma-1 (S1R) receptors; by binding steroid receptors: androgen and estrogen receptors (ARs, ERα, or ERβ); or by their metabolism to more potent sex steroid hormones, e.g., testosterone, dihydrotestosterone, and estradiol, which bind with higher affinity to ARs and ERs. DHEA inhibits voltage-gated T-type calcium channels. DHEA activates peroxisome proliferator-activated receptor (PPARα) and CAR by a mechanism apparently involving PP2A, a protein phosphatase dephosphorylating PPARα and CAR to activate their transcriptional activity. We review our recent study showing DHEA activated GPER1 (G-protein-coupled estrogen receptor 1) in HepG2 cells to stimulate miR-21 transcription. This chapter reviews some of the physiological, biochemical, and molecular mechanisms of DHEA and DHEA-S activity.

Testosterone and androstanediol glucuronide among men in NHANES III

Background

Most of the androgen replacement therapies were based on serum testosterone and without measurements of total androgen activities. Whether those with low testosterone also have low levels of androgen activity is largely unknown. We hence examined the association between testosterone and androstanediol glucuronide (AG), a reliable measure of androgen activity, in a nationally representative sample of US men.

Methods

Cross-sectional analysis was based on 1493 men from the Third National Health and Nutrition examination Survey (NHANES III) conducted from 1988 to 1991. Serum testosterone and AG were measured by immunoassay. Kernel density was used to estimate the average density of serum AG concentrations by quartiles of testosterone.

Results

Testosterone was weakly and positively correlated with AG (correlation coefficient = 0.18). The kernel density estimates show that the distributions are quite similar between the quartiles of testosterone. After adjustment for age, the distributions of AG in quartiles of testosterone did not change. The correlation between testosterone and AG was stronger in men with younger age, lower body mass index, non-smoking and good self-rated health and health status.

Conclusions

Serum testosterone is weakly correlated with total androgen activities, and the correlation is even weaker for those with poor self-rated health. Our results suggest that measurement of total androgen activity in addition to testosterone is necessary in clinical practice, especially before administration of androgen replacement therapy.

Novel Selective Agents for the Degradation of Androgen Receptor Variants to Treat Castration-Resistant Prostate Cancer

Androgen receptor (AR) mediates the growth of prostate cancer throughout its course of development, including in abnormal splice variants (AR-SV)-driven advanced stage castration-resistant disease. AR stabilization by androgens makes it distinct from other steroid receptors, which are typically ubiquitinated and degraded by proteasomes after ligand binding. Thus, targeting AR in advanced prostate cancer requires the development of agents that can sustainably degrade variant isoforms for effective therapy. Here we report the discovery and characterization of potent selective AR degraders (SARD) that markedly reduce the activity of wild-type and splice variant isoforms of AR at submicromolar doses. Three SARDs (UT-69, UT-155, and (R)-UT-155) bind the amino-terminal transcriptional activation domain AF-1, which has not been targeted for degradation previously, with two of these SARD (UT-69 and UT-155) also binding the carboxy-terminal ligand binding domain. Despite different mechanisms of action, all three SARDs degraded wild-type AR and inhibited AR function, exhibiting greater inhibitory potency than the approved AR antagonists. Collectively, our results introduce a new candidate class of next-generation therapeutics to manage advanced prostate cancer. Cancer Res; 77(22); 6282-98. ©2017 AACR.

[Androgen receptor variants in prostate cancer]

Prostate cancer is a public health concern as it currently represents the most frequent malignancy in men in Europe. Progression of this hormone-dependent cancer is driven by androgens. Thus, the most common treatment for patients with advanced prostate cancer consists in an androgen ablation by castration therapy. However, the majority of patients relapses and develops a castration-resistant prostate cancer. This failure of androgen deprivation is related to the emergence of mutant and splice variants of the androgen receptor. Indeed, androgen receptor variants are ligand-independent, constitutively active and thus able to induce resistance to castration. This review focuses on AR variants signaling pathways and their role in resistance to castration and prostate cancer progression.

CXCL13 is androgen-responsive and involved in androgen induced prostate cancer cell migration and invasion

Androgen receptor (AR) is a key transcription factor playing a critical role in prostate cancer (PCa) initiation and progression. However, the molecular mechanisms of AR action in prostate cancer are not very clear. CXCL13, known as B cell attracting chemokine1 (BCA-1), is a member of CXC chemokine family and relevant to cancer metastasis. This study shows that CXCL13 is an androgen-responsive gene and involved in AR-induced PCa cell migration and invasion. In clinical specimens, expression of CXCL13 in PCa tissues is markedly higher than that in adjacent normal tissues. In cultures, expression of CXCL13 is up-regulated by androgen-AR axis at both mRNA and protein levels. Furthermore, Chip-Seq assay identifies canonical androgen responsive elements (ARE) at CXCL13 enhancer and dual-luciferase reporter assays reveals that the ARE is highly responsive to androgen while mutations of the ARE abolish the reporter activity. Additional chromatin immunoprecipitation (ChIP) assays also identify that the ARE presents androgen responsiveness. In addition, CXCL13 promotes G2/M phase transition by increasing Cyclin B1 levels in PCa cells. Functional studies demonstrate that reducing endogenous CXCL13 expression in LNCaP cells largely weakens androgen-AR axis induced cell migration and invasion. Taken together, our study implicates for the first time that CXCL13 is an AR target gene and involved in AR-mediated cell migration and invasion in primary PCa.

Investigation of the In Vitro and In Vivo efficiency of RM-532-105, a 17β-hydroxysteroid dehydrogenase type 3 inhibitor, in LAPC-4 prostate cancer cell and tumor models

In the fight against androgen-sensitive prostate cancer, the enzyme 17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3) is an attractive therapeutic target considering its key role in the formation of androgenic steroids. In this study, we attempted to assess the in vivo efficacy of the compound RM-532-105, an androsterone derivative developed as an inhibitor of 17β-HSD3, in the prostate cancer model of androgen-sensitive LAPC-4 cells xenografted in nude mice. RM-532-105 did not inhibit the tumor growth induced by 4-androstene-3,17-dione (4-dione); rather, the levels of the androgens testosterone (T) and dihydrotestosterone (DHT) increased within the tumors. In plasma, however, DHT levels increased but T levels did not. In troubleshooting experiments, the non-androgenic potential of RM-532-105 was confirmed by two different assays (LAPC-4 proliferation and androgen receptor transcriptional activity assays). The enzyme 5α-reductase was also revealed to be the predominant enzyme metabolizing 4-dione in LAPC-4 cells, yielding 5α-androstane-3,17-dione and not T. Other 17β-HSDs than 17β-HSD3 seem responsible in the androgen synthesis. From experiments with LAPC-4 cells, we fortuitously came across the interesting finding that 17β-HSD3 inhibitor RM-532-105 is concentrated inside tumors.

Resistance to Hormonal Therapy in Prostate Cancer

Several therapeutic strategies are actually available in the management of prostate cancer: Targeting the androgen receptor (AR) is the goal both for initial androgen deprivation therapy (ADT) and second-generation androgen ablative agents (abiraterone and enzalutamide). Chemotherapy with taxanes, administered upon progression or as first line approach in association with ADT, is another therapeutic option. Unfortunately, none of these therapies is curative and patients are destined to develop a resistant phenotype.Progression to ADT leads to the attainment of a castration resistant disease whose mechanisms remain incompletely understood. Reactivation of AR has been shown to occur and second-generation of AR targeting drugs are usually prescribed. Upon progression to these agents AR signaling still remains the primary driver although it often becomes ligand independent, since it can be either restored through mutations on the ligand binding domain and/or formation of AR splicing variants or by passed through a cross talk with other oncogenic signaling pathways.AR-independent signaling pathways may represent additional mechanisms underlying castration resistant progression. It is clear that castration resistant prostate cancer is a group of diverse diseases and new treatment paradigms need to be developed.

Quality of life effects of androgen deprivation therapy in a prostate cancer cohort in New Zealand: can we minimize effects using a stratification based on the aldo-keto reductase family 1, member C3 rs12529 gene polymorphism?

BACKGROUND

Androgen deprivation therapy (ADT) is an effective palliation treatment in men with advanced prostate cancer (PC). However, ADT has well documented side effects that could alter the patient's health-related quality of life (HRQoL). The current study aims to test whether a genetic stratification could provide better knowledge for optimising ADT options to minimize HRQoL effects.

METHODS

A cohort of 206 PC survivors (75 treated with and 131 without ADT) was recruited with written consent to collect patient characteristics, clinical data and HRQoL data related to PC management. The primary outcomes were the percentage scores under each HRQoL subscale assessed using the European Organisation for Research and Treatment of Cancer Quality of Life questionnaires (QLQ-C30 and PR25) and the Depression Anxiety Stress Scales developed by the University of Melbourne, Australia. Genotyping of these men was carried out for the aldo-keto reductase family 1, member C3 (AKR1C3) rs12529 single nucleotide polymorphism (SNP). Analysis of HRQoL scores were carried out against ADT duration and in association with the AKR1C3 rs12529 SNP using the generalised linear model. P-values <0 · 05 were considered significant, and were further tested for restriction with Bonferroni correction.

RESULTS

Increase in hormone treatment-related effects were recorded with long-term ADT compared to no ADT. The C and G allele frequencies of the AKR1C3rs12529 SNP were 53·4 % and 46·6 % respectively. Hormone treatment-related symptoms showed an increase with ADT when associated with the AKR1C3 rs12529 G allele. Meanwhile, decreasing trends on cancer-specific symptoms and increased sexual interest were recorded with no ADT when associated with the AKR1C3 rs12529 G allele and reverse trends with the C allele. As higher incidence of cancer-specific symptoms relate to cancer retention it is possible that associated with the C allele there could be higher incidence of unresolved cancers under no ADT options.

CONCLUSIONS

If these findings can be reproduced in larger homogeneous cohorts, a genetic stratification based on the AKR1C3 rs12529 SNP, can minimize ADT-related HRQoL effects in PC patients. Our data additionally show that with this stratification it could also be possible to identify men needing ADT for better oncological advantage.

Role of the Androgen-Androgen Receptor Axis in the Treatment Resistance of Advanced Prostate Cancer: From Androgen-Dependent to Castration Resistant and Further

After the introduction of prostate-specific antigen (PSA) screening, prostate cancer diagnosis has shifted to early and curative stages, although 10-20% of patients still present with metastatic and incurable cancer. Prostate cancer is androgen-dependent, and most patients with prostate cancer initially respond to androgen deprivation therapy (ADT). After 1-2 years of the treatment, advanced prostate cancer eventually progresses to castration resistant prostate cancer (CRPC). A variety of mechanisms of progression from androgen-dependent prostate cancer to CRPC under ADT have been postulated, and the key pathway is re-activation of the androgen-androgen receptor (AR) axis, for example, caused by AR mutation/overexpression/splice variants, altered expression of AR cofactors, and increased production of androgens. Recently approved new agents, such as the hormonal agents abiraterone and enzalutamide and the chemotherapeutic agent cabazitaxel, have demonstrated survival benefit in men with CRPC. However, the prolongation of survival times provided with these agents is limited because of the treatment resistance. Androgen-AR axis still plays a pivotal role in the resistance to the new agents for CRPC. To improve the prognosis of patients with CRPC, intensive research to identify effective agents, treatment strategies, and useful predictive biomarkers to select the patients who can benefit from such treatments are required. Additional clinical data, with a better understanding of the biology of CRPC, may provide better CRPC treatment outcomes. This article reviews the underlying mechanisms of treatment resistance and future direction of CRPC treatments.

New insights into the androgen biotransformation in prostate cancer: A regulatory network among androgen, androgen receptors and UGTs

Androgen, as one kind of steroid hormones, is pivotal in the hormone-sensitive cancer, such as prostate cancer (PCa). The synthesis, elimination, and bioavailability of androgen in prostate cells have been proved to be a main cause of the carcinogenesis, maintenance and deterioration of PCa. This review illustrates the outlines of androgen biotransformation, and further discusses the different enzymes, especially UDP-glucuronyltransferases (UGTs) embedded in both benign and malignant prostate cells, which catalyze the reactions. Although many inhibitors of the enzymes responsible for the synthesis of androgens have been developed into drugs to fight against PCa, the elimination procedures metabolized by the UGTs are less emphasized. Thus the regulatory network among androgen, androgen receptors (AR) and UGTs is carefully reviewed in this article, indicating the determinant effects of UGTs on prostatic androgens and the regulation of AR. Finally, the hypothesis is also put forward that the regulators of UGTs may be developed to accelerate the androgen elimination and benefit PCa therapy.

Co-targeting AR and HSP90 suppresses prostate cancer cell growth and prevents resistance mechanisms

Persistent androgen receptor (AR) signaling in castration resistant prostate cancer (CRPC) underpins the urgent need for therapeutic strategies that better target this pathway. Combining classes of agents that target different components of AR signaling has the potential to delay resistance and improve patient outcomes. Many oncoproteins, including the AR, rely on the molecular chaperone heat shock protein 90 (Hsp90) for functional maturation and stability. In this study, enhanced anti-proliferative activity of the Hsp90 inhibitors 17-allylamino-demethoxygeldanamycin (17-AAG) and AUY922 in androgen-sensitive and CRPC cells was achieved when the agents were used in combination with AR antagonists bicalutamide or enzalutamide. Moreover, significant caspase-dependent cell death was achieved using sub-optimal agent doses that individually have no effect. Expression profiling demonstrated regulation of a broadened set of AR target genes with combined 17-AAG and bicalutamide compared with the respective single agent treatments. This enhanced inhibition of AR signaling was accompanied by impaired chromatin binding and nuclear localization of the AR. Importantly, expression of the AR variant AR-V7 that is implicated in resistance to AR antagonists was not induced by combination treatment. Likewise, the heat shock response that is typically elicited with therapeutic doses of Hsp90 inhibitors, and is a potential mediator of resistance to these agents, was significantly reduced by combination treatment. In summary, the co-targeting strategy in this study more effectively inhibits AR signaling than targeting AR or HSP90 alone and prevents induction of key resistance mechanisms in prostate cancer cells. These findings merit further evaluation of this therapeutic strategy to prevent CRPC growth.

Biological activity of pyrazole and imidazole-dehydroepiandrosterone derivatives on the activity of 17β-hydroxysteroid dehydrogenase

The enzyme type 5 17β-hydroxysteroid dehydrogenase 5 (17β-HSD5) catalyzes the transformation of androstenedione (4-dione) to testosterone (T) in the prostate. This metabolic pathway remains active in cancer patients receiving androgen deprivation therapy. Since physicians seek to develop advantageous and better new treatments to increase the average survival of these patients, we synthesized several different dehydroepiandrosterone derivatives. These compounds have a pyrazole or imidazole function at C-17 and an ester moiety at C-3 and were studied as inhibitors of 17β-HSD5. The kinetic parameters of this enzyme were determined for use in inhibition assays. Their pharmacological effect was also determined on gonadectomized hamsters treated with Δ(4)-androstenedione (4-dione) or testosterone (T) and/or the novel compounds. The results indicated that the incorporation of a heterocycle at C-17 induced strong 17β-HSD5 inhibition. These derivatives decreased flank organ diameter and prostate weight in castrated hamsters treated with T or 4-dione. Inhibition of 17β-HSD5 by these compounds could have therapeutic potential for the treatment of prostate cancer and benign prostatic hyperplasia.

Structures of complexes of type 5 17β-hydroxysteroid dehydrogenase with structurally diverse inhibitors: insights into the conformational changes upon inhibitor binding

Type 5 17β-hydroxysteroid dehydrogenase (17β-HSD5) is an aldo-keto reductase expressed in the human prostate which catalyzes the conversion of androstenedione to testosterone. Testosterone is converted to 5α-dihydrotestosterone, which is present at high concentrations in patients with castration-resistant prostate cancer (CRPC). Inhibition of 17β-HSD5 is therefore considered to be a promising therapy for treating CRPC. In the present study, crystal structures of complexes of 17β-HSD5 with structurally diverse inhibitors derived from high-throughput screening were determined. In the structures of the complexes, various functional groups, including amide, nitro, pyrazole and hydroxyl groups, form hydrogen bonds to the catalytic residues His117 and Tyr55. In addition, major conformational changes of 17β-HSD5 were observed following the binding of the structurally diverse inhibitors. These results demonstrate interactions between 17β-HSD5 and inhibitors at the atomic level and enable structure-based drug design for anti-CRPC therapy.

Testosterone Replacement Therapy in Hypogonadal Men Following Prostate Cancer Treatment: A Questionnaire-Based Retrospective Study among Urologists in Bavaria, Germany

Background: Several reports suggest testosterone replacement therapy (TRT) may be an option in selected hypogonadal patients with a history of prostate cancer (PCa) and no evidence of disease after curative treatment. Our aim was to assess TRT experience and patient management among urologists in Bavaria. Materials and Methods: Questionnaires were developed and mailed to all registered urologists in Bavaria (n = 420) regarding their experience with TRT in patients with treated PCa. Results: One hundred and ninety-three (46%) urologists returned the questionnaire and reported their experience with TRT in hypogonadal patients after curative treatment for PCa. Complete data was available for 32 men. Twenty-six patients (81%) received TRT after prostatectomy, 1 patient after external beam radiation, 3 patients after high-dose brachytherapy and 2 patients after high-intensity focused ultrasound. Of the PCa cases, 88.5% (23/26) were organ confined (pT2a-c), and 3 were pT3 tumors. All patients were pN0/cN0, and only 1 patient (pT3a) had a positive surgical margin status postoperatively. After a mean follow-up of 39.8 months, no biochemical relapse was observed. Conclusion: To date, there is no clear evidence to withhold TRT from hypogonadal men after curative PCa treatment. Our findings, although with limitations, fit in with the available data showing that TRT does not put patients at an increased risk after curative treatment of PCa.

Combined blockade of testicular and locally made androgens in prostate cancer: a highly significant medical progress based upon intracrinology

Recently two drugs, namely the antiandrogen MDV-3100 and the inhibitor of 17α-hydroxylase abiraterone have been accepted by the FDA for the treatment of castration-resistant prostate cancer (CRPC) with or without previous chemotherapy, with a prolongation of overall survival of 2.2-4.8 months. While medical (GnRH agonist) or surgical castration reduces the serum levels of testosterone by about 97%, an important concentration of testosterone and dihydrotestosterone remains in the prostate and activates the androgen receptor (AR), thus offering an explanation for the positive data obtained in CRPC. In fact, explanation of the response observed with MDV-3100 or enzalutamide in CRPC is essentially a blockade of the action or formation of intraprostatic androgens. In addition to the inhibition of the action or formation of androgens made locally by the mechanisms of intracrinology, increased AR levels and AR mutations can be involved, especially in very advanced disease. Future developments look at more efficient inhibitors of the action or formation of intraprostatic androgens and starting treatment earlier when blockade of androgens can exert long-term control and even cure prostate cancer treated at a stage before the appearance of metastases. This article is part of a Special Issue entitled 'Essential role of DHEA'.

Androgen metabolism in prostate cancer: from molecular mechanisms to clinical consequences

Despite our most vigorous efforts, prostate cancer remains the second leading cause of cancer death in men. Understanding the intricacies of androgen metabolism is vital to finding therapeutic targets, particularly with progression of advanced prostate cancer after initial hormone therapy, where adrenal precursors are involved. Such is the case with castration-resistant prostate cancer, where adrenal androgens, for example, dehydroepiandrosterone, are a source for intratumoural synthesis of dihydrotestosterone. As prostate cancer progresses, androgen metabolism changes due to altered expression of steroidogenic enzymes and mutations in the components of the steroidogenic machinery. These alterations sustain disease and allow progression; mechanistically, they may also enable development of hormone therapy resistance. With the development of the newer agents, abiraterone acetate and enzalutamide, efforts have been made to better define the basis for response and resistance. This work can be carried out in cell lines, animal models, as well as with ex vivo analysis of tissues obtained from patients. Efforts to further elucidate the finer details of the steroidogenic pathway are necessary to move toward a curative paradigm for patients with localised disease at high risk for recurrence.

Intratumoral steroidogenesis in castration-resistant prostate cancer: a target for therapy

Development of castration-resistant prostate cancer (CRPC) in a low androgen environment, arising from androgen deprivation therapy (ADT), is a major problem in patients with advanced prostate cancer (PCa). Several mechanisms have been hypothesized to explain the progression of PCa to CRPC during ADT, one of them is so called persistent intratumoral steroidogenesis. The existence of intratumoral steroidogenesis was hinted based on the residual levels of intraprostatic testosterone (T) and dihydrotestosterone (DHT) after ADT. Accumulating evidence has shown that the intraprostatic androgen levels after ADT are sufficient to induce cancer progression. Several studies now have demonstrated that PCa cells are able to produce T and DHT from different androgen precursors, such as cholesterol and the adrenal androgen, dehydroepiandrosterone (DHEA). Furthermore, up-regulation of genes encoding key steroidogenic enzymes in PCa cells seems to be an indicator for active intratumoral steroidogenesis in CRPC cells. Currently, several drugs are being developed targeting those steroidogenic enzymes, some of which are now in clinical trials or are being used as standard care for CRPC patients. In the future, novel agents that target steroidogenesis may add to the arsenal of drugs for CRPC therapy.

GnRH agonists and the rapidly increasing use of combined androgen blockade in prostate cancer

The discovery of medical castration with GnRH agonists in 1979 rapidly replaced surgical castration and high doses of estrogens for the treatment of prostate cancer. Soon afterwards, it was discovered that androgens were made locally in the prostate from the inactive precursor DHEA of adrenal origin, a mechanism called intracrinology. Taking into account these novel facts, combined androgen blockade (CAB) using a pure antiandrogen combined with castration in order to block the two sources of androgens was first published in 1982. CAB was the first treatment shown in randomized and placebo-controlled trials to prolong life in prostate cancer, even at the metastatic stage. Most importantly, the results recently obtained with the novel pure antiandrogen enzalutamide as well as with abiraterone, an inhibitor of 17α-hydroxylase in castration-resistant prostate cancer, has revitalized the CAB concept. The effects of CAB observed on survival of heavily pretreated patients further demonstrates the importance of the androgens made locally in the prostate and are a strong motivation to apply CAB to efficiently block all sources of androgens earlier at start of treatment and, even better, before metastasis occurs. The future of research in this field thus seems to be centered on the development of more potent blockers of androgens formation and action in order to obtain better results at the metastatic stage and, for the localized stage, reduce the duration of treatment required to achieve complete apoptosis and control of prostate cancer proliferation before it reaches the metastatic or noncurable stage.

Overexpression of HepaCAM inhibits cell viability and motility through suppressing nucleus translocation of androgen receptor and ERK signaling in prostate cancer

BACKGROUND

HepaCAM is suppressed in a variety of human cancers, and involved in cell adhesion, growth, migration, invasion, and survival. However, the expression and function of HepaCAM in prostate cancer are still unknown.

METHODS

HepaCAM expression has been detected by RT-PCR, Western blotting and immunohistochemistry staining in prostate cell lines RWPE-1, LNCap, DU145, PC3, and in 75 human prostate tissue specimens, respectively. Meanwhile, the cell proliferation ability was detected by WST-8 assay. The role of HepaCAM in prostate cancer cell migration and invasion was examined by wound healing and transwell assay. And flow cytometry was used to observe the apoptosis of prostate cancer cells. Then we detected changes of Androgen Receptor translocation and ERK signaling using immunofluorescence staining and western blot after overexpression of HepaCAM.

RESULTS

The HepaCAM expression was significantly down-regulated in prostate cancer tissues and undetected in prostate cancer cells. However, the low HepaCAM expression was not statistically associated with clinicopathological characteristics of prostate cancer. Overexpression of HepaCAM in prostate cancer cells decreased the cell proliferation, migration and invasion, and induced the cell apoptosis. Meanwhile, HepaCAM prevented the androgen receptor translocation from the cytoplasm to the nucleus and down-regulated the MAPK/ERK signaling.

CONCLUSION

Our results suggested that HepaCAM acted as a tumor suppressor in prostate cancer. HepaCAM inhibited cell viability and motility which might be through suppressing the nuclear translocation of Androgen Receptor and down-regulating the ERK signaling. Therefore, it was indicated that HepaCAM may be a potential therapeutic target for prostate cancer.

Can Mathematical Models Predict the Outcomes of Prostate Cancer Patients Undergoing Intermittent Androgen Deprivation Therapy?

Androgen deprivation therapy is a common treatment for advanced or metastatic prostate cancer. Like the normal prostate, most tumors depend on androgens for proliferation and survival but often develop treatment resistance. Hormonal treatment causes many undesirable side effects which significantly decrease the quality of life for patients. Intermittently applying androgen deprivation in cycles reduces the total duration with these negative effects and may reduce selective pressure for resistance. We extend an existing model which used measurements of patient testosterone levels to accurately fit measured serum prostate specific antigen (PSA) levels. We test the model's predictive accuracy, using only a subset of the data to find parameter values. The results are compared with those of an existing piecewise linear model which does not use testosterone as an input. Since actual treatment protocol is to re-apply therapy when PSA levels recover beyond some threshold value, we develop a second method for predicting the PSA levels. Based on a small set of data from seven patients, our results showed that the piecewise linear model produced slightly more accurate results while the two predictive methods are comparable. This suggests that a simpler model may be more beneficial for a predictive use compared to a more biologically insightful model, although further research is needed in this field prior to implementing mathematical models as a predictive method in a clinical setting. Nevertheless, both models are an important step in this direction.

SGK3 is an androgen-inducible kinase promoting prostate cancer cell proliferation through activation of p70 S6 kinase and up-regulation of cyclin D1

Both androgen and phosphatidylinositol 3-kinase (PI3K) signaling are critical for cell proliferation of androgen receptor (AR)-positive prostate cancer cells, but the underlying mechanisms are still not fully understood. Here we report that serum- and glucocorticoid-inducible kinase 3 (SGK3), a Ser/Thr kinase functioning downstream of PI3K, is an AR transcriptional target and promotes prostate cancer cell proliferation. SGK3 expression is up-regulated by androgen DHT via AR. We identified an AR-binding region at the sgk3 locus, which confers androgen responsiveness of sgk3 promoters. Interestingly, we found that androgen/AR-dependent SGK3 expression requires estrogen receptor (ER) (including both isoforms, ERα and ERβ). Depletion of ER blocked DHT-induced SGK3 expression. Functionally, knockdown of SGK3 expression significantly decreased LNCaP prostate cancer cell proliferation by inhibiting G1 to S phase cell cycle progression. We further provided evidence that SGK3 promotes p70 S6 kinase (p70S6K) activation and increases cyclin D1 levels. In summary, our study identifies SGK3 as an AR target and provides a novel androgen-induced cell proliferation mechanism mediated by the AR-SGK3-p70S6K-cyclin D1 pathway in prostate cancer cells.

Characterization of prostate cancer bone metastases according to expression levels of steroidogenic enzymes and androgen receptor splice variants

Background

Intra-tumoral steroidogenesis and constitutive androgen receptor (AR) activity have been associated with castration-resistant prostate cancer (CRPC). This study aimed to examine if CRPC bone metastases expressed higher levels of steroid-converting enzymes than untreated bone metastases. Steroidogenic enzyme levels were also analyzed in relation to expression of constitutively active AR variants (AR-Vs) and to clinical and pathological variables.

Methodology/Principal Findings

Untreated, hormone-naïve (HN, n = 9) and CRPC bone metastases samples (n = 45) were obtained from 54 patients at metastasis surgery. Non-malignant and malignant prostate samples were acquired from 13 prostatectomy specimens. Transcript and protein levels were analyzed by real-time RT-PCR, immunohistochemistry and immunoblotting. No differences in steroidogenic enzyme levels were detected between CRPC and HN bone metastases. Significantly higher levels of SRD5A1, AKR1C2, AKR1C3, and HSD17B10 mRNA were however found in bone metastases than in non-malignant and/or malignant prostate tissue, while the CYP11A1, CYP17A1, HSD3B2, SRD5A2, and HSD17B6 mRNA levels in metastases were significantly lower. A sub-group of metastases expressed very high levels of AKR1C3, which was not due to gene amplification as examined by copy number variation assay. No association was found between AKR1C3 expression and nuclear AR staining, tumor cell proliferation or patient outcome after metastases surgery. With only one exception, high AR-V protein levels were found in bone metastases with low AKR1C3 levels, while metastases with high AKR1C3 levels primarily contained low AR-V levels, indicating distinct mechanisms behind castration-resistance in individual bone metastases.

Conclusions/Significance

Induced capacity of converting adrenal-gland derived steroids into more potent androgens was indicated in a sub-group of PC bone metastases. This was not associated with CRPC but merely with the advanced stage of metastasis. Sub-groups of bone metastases could be identified according to their expression levels of AKR1C3 and AR-Vs, which might be of relevance for patient response to 2^nd line androgen-deprivation therapy.

Mechanisms of androgen receptor activation in castration-resistant prostate cancer

Systemic treatment of advanced prostate cancer is initiated with androgen deprivation therapy by gonadal testosterone depletion. Response durations are variable and tumors nearly always become resistant as castration-resistant prostate cancer (CRPC), which is driven, at least in part, by a continued dependence on the androgen receptor (AR). The proposed mechanisms that underlie AR function in this clinical setting are quite varied. These include intratumoral synthesis of androgens from inactive precursors, increased AR expression, AR activation through tyrosine kinase-dependent signaling, alterations in steroid receptor coactivators, and expression of a truncated AR with constitutive activity. Various pharmacologic interventions have clinically validated some of these mechanisms, such as those that require the AR ligand-binding domain. Clinical studies have failed to validate other mechanisms, and additional mechanisms have yet to be tested in patients with CRPC. Here, we review the mechanisms that elicit AR activity in CRPC, with a particular focus on recent developments.