Androgen receptor-dependent and -independent mechanisms driving prostate cancer progression: Opportunities for therapeutic targeting from multiple angles

Androgen and Androgen Receptors as Regulators of Monocyte and Macrophage Biology in the Healthy and Diseased Lung

Androgens, the predominant male sex hormones, drive the development and maintenance of male characteristics by binding to androgen receptor (AR). As androgens are systemically distributed throughout the whole organism, they affect many tissues and cell types in addition to those in male sexual organs. It is now clear that the immune system is a target of androgen action. In the lungs, many immune cells express ARs and are responsive to androgens. In this review, we describe the effects of androgens and ARs on lung myeloid immune cells-monocytes and macrophages-as they relate to health and disease. In particular, we highlight the effect of androgens on lung diseases, such as asthma, chronic obstructive pulmonary disease and lung fibrosis. We also discuss the therapeutic use of androgens and how circulating androgens correlate with lung disease. In addition to human studies, we also discuss how mouse models have helped to uncover the effect of androgens on monocytes and macrophages in lung disease. Although the role of estrogen and other female hormones has been broadly analyzed in the literature, we focus on the new perspectives of androgens as modulators of the immune system that target myeloid cells during lung inflammation.

Altered expression of cytochrome P450 enzymes involved in metabolism of androgens and vitamin D in the prostate as a risk factor for prostate cancer

Prostate cancer is the most common malignant disease among men. The signaling pathways, regulated by the androgen and vitamin D receptors, play a key role in prostate cancer. The intracellular level of androgens and vitamin D determines not only receptor functionality, but also the efficacy of cellular processes regulated by them (cell proliferation, apoptosis, differentiation etc.). It is known that several androgen-metabolizing P450s (CYP3A4/5/43 and CYP2B6) and P450 enzymes (CYP2R1, CYP27A1, CYP27B1, CYP24A1, CYP3A4, CYP2J2), which are necessary for vitamin D metabolism, are expressed in the prostate. It was shown that alterations in an expression pattern of the certain cytochrome P450s might lead to the development of castration-resistant cancer (CYP3A4, CYP2J2, CYP24A1), and to chemo-resistance (CYP3A4, CYP3A5, CYP2B6) and early mortality (CYP2B6, CYP27A1, CYP24A1). Moreover, steroidogenic CYPs (CYP17A1, CYP11A1) are not expressed in normal prostate tissue. Alterations in their expression levels in steroidogenic tissues are closely associated with carcinogenesis, and, most importantly, with the development of aggressive forms of prostate cancer. Hence, it is important, to study how expression of CYPs in the prostate might be regulated, to understand the mechanisms of disease development and to improve the effectiveness of therapy. Several CYPs (CYP3A43, CYP2B6, CYP27A1, CYP24A1) can be considered as prognostic and diagnostic markers of prostate cancer. To propose personalized treatment, individual differences in CYP expression should be taken into account.

Ca2+ as a therapeutic target in cancer

Ca2+ is a ubiquitous and dynamic second messenger molecule that is induced by many factors including receptor activation, environmental factors, and voltage, leading to pleiotropic effects on cell function including changes in migration, metabolism and transcription. As such, it is not surprising that aberrant regulation of Ca2+ signals can lead to pathological phenotypes, including cancer progression. However, given the highly context-specific nature of Ca2+-dependent changes in cell function, delineation of its role in cancer has been a challenge. Herein, we discuss the distinct roles of Ca2+ signaling within and between each type of cancer, including consideration of the potential of therapeutic strategies targeting these signaling pathways.

Dietary Tomato or Lycopene Do Not Reduce Castration-Resistant Prostate Cancer Progression in a Murine Model

BACKGROUND

Dietary tomato products or lycopene protect against prostate carcinogenesis, but their impact on the emergence of castration-resistant prostate cancer (CRPC) is unknown.

OBJECTIVE

We hypothesized that tomato or lycopene products would reduce the emergence of CRPC.

METHODS

Transgenic adenocarcinoma of the mouse prostate (TRAMP) mice were castrated at 12-13 wk and the emergence of CRPC was monitored by ultrasound in each study. In Study 1, TRAMP mice (n = 80) were weaned onto an AIN-93G-based control diet (Con-L, n = 28), a 10% tomato powder diet (TP-L, 10% lyophilized w/w, n = 26), or a control diet followed by a tomato powder diet after castration (TP-Int1, n = 26). In Study 2, TRAMP mice (n = 85) were randomized onto a control diet with placebo beadlets (Con-Int, n = 29), a tomato diet with placebo beadlets (TP-Int2, n = 29), or a control diet with lycopene beadlets (Lyc-Int, n = 27) following castration (aged 12 wk). Tumor incidence and growth were monitored by ultrasound beginning at an age of 10 wk. Mice were euthanized 4 wk after tumor detection or aged 30 wk if no tumor was detected. Tissue weights were compared by ANOVA followed by Dunnett's test. Tumor volumes were compared using generalized linear mixed model regression.

RESULTS

Ultrasound estimates for the in vivo tumor volume were strongly correlated with tumor weight at necropsy (R2 = 0.75 and 0.94, P <0.001 for both Studies 1 and 2, respectively). Dietary treatments after castration did not significantly impact cancer incidence, time to tumor detection, or final tumor weight.

CONCLUSIONS

In contrast to studies of de novo carcinogenesis in multiple preclinical models, tomato components had no significant impact on the emergence of CRPC in the TRAMP model. It is possible that specific mutant subclones of prostate cancer may continue to show some antiproliferative response to tomato components, but further studies are needed to confirm this.

Stromal-AR influences the growth of epithelial cells in the development of benign prostate hyperplasia

Activation of epithelial-AR signaling is identified as the major cause of hyperproliferation of the cells during benign and malignant prostate conditions. However, the contribution of stromal-AR is also precarious due to its secretory actions that contribute to the progression of benign and malignant tumors. The present study was aimed to understand the influence of stromal-AR mediated actions on epithelial cells during BPH condition. The secretome (conditioned media-CM) was collected from AR agonist (testosterone-propionate-TP) and antagonist (Nilutamide-Nil) treated BPH patient-derived stromal cells and exposed to BPH epithelial cells. Epithelial cells exhibited increased cell proliferation with the treatment of CM derived from TP-treated stromal cells (TP-CM) but did not support the clonogenic growth of BPH epithelial cells. However, CM derived from Nil-treated stromal cells (Nil-CM) depicted delayed and aggressive BPH epithelial cell proliferation with increased clonogenicity of BPH epithelial cells. Further, decreased AR levels with increased cMyc transcripts and pAkt levels also validated the clonogenic transformation under the paracrine influence of inhibition of stromal-AR. Moreover, the CM of stromal-AR activation imparted positive regulation of basal/progenitor pool through LGR4, β-Catenin, and ΔNP63α expression. Hence, the present study highlighted the restricted disease progression and retains the basal/progenitor state of BPH epithelial cells through the activation of stromal-AR. On the contrary, AR-independent aggressive BPH epithelial cell growth due to paracrine action of loss stromal-AR directs us to reform AR pertaining treatment regimes for better clinical outcomes.

miR-30a inhibits androgen-independent growth of prostate cancer via targeting MYBL2, FOXD1, and SOX4

BACKGROUND

Castrate-resistant prostate cancer (CRPC) is an aggressive and lethal disease. The pathogenesis of CRPC is not fully understood and novel therapeutic targets need to be identified to improve the patients' prognosis. MicroRNA-30a (miR-30a) has been demonstrated to be a tumor suppressor in many types of solid malignancies. However, its role in androgen-independent (AI) growth of prostate cancer (PCa) received limited attention as yet.

METHODS

The clinical association of miR-30a and its potential targets with AI growth was characterized by bioinformatics analyses. Regulation of cell proliferation and colony formation rates by miR-30a were tested using PCa cell models. Xenograft models were used to measure the regulation of prostate tumor growth by miR-30a. The real-time quantitative polymerase chain reaction was used to validate whether miR-30a and its targets regulate cell cycle control genes and androgen receptor (AR)-dependent transcription. Bioinformatics tools, Western blot, and luciferase reporter assays were utilized to identify miR-30a targets.

RESULTS

Bioinformatic analysis showed that low expression of miR-30a is associated with castration resistance of PCa patients and poor outcomes. Transfection of miR-30a mimics inhibited the AI growth of PCa cells in vitro and in vivo. Upregulation of miR-30a in 22RV1 cells altered the expression of cell cycle control genes and AR-mediated transcription, while downregulation of miR-30a in LNCaP cells had the opposite effects to AR-mediated transcription. MYBL2, FOXD1, and SOX4 were identified as miR-30a targets. Downregulation of MYBL2, FOXD1, and SOX4 affected the expression of cell cycle control genes and AR-mediated transcription and suppressed the AI growth of 22RV1 cells.

CONCLUSIONS

Our results suggest that miR-30a inhibits AI growth of PCa by targeting MYBL2, FOXD1, and SOX4. They provide novel insights into developing new treatment strategies for CRPC.

Prognostic value of microRNA-20b expression level in patients with prostate cancer

BACKGROUND

miR-20b is a member of the miR-106a-363 gene cluster located in the mammalian X chromosome, the larger miR-17 family, and the miR-17-92 and miR-106b-25 gene clusters. Previous studies have indicated that miR-20b may function as oncogene or tumor suppressor in different types of cancers. The present study analyzed the association between miR-20b and clinicopathological characteristics of patients with prostate cancer.

METHODS

A total of 127 pairs of prostate cancer tissue samples and adjacent prostate tissue samples were collected from April 2013 to March 2018. The associations between miR-20b expression levels and clinicopathological factors were assessed using the χ2‑test. Survival was estimated using the Kaplan-Meier method, and the differences in survival according to miR-20b expression were compared using the log-rank test. Prognostic values of miR-20b expression and clinical outcomes were evaluated by Cox regression analysis.

RESULTS

The relative expression of miR-20b in prostate cancer tissues was significantly higher than that in adjacent noncancerous prostate tissues (P<0.001). miR-20b expression was observed to be significantly associated with Gleason score (P<0.001), lymph node metastasis (P<0.001), and TNM stage (P=0.002). The log-rank test indicated that patients with increased miR-20b expression experienced poor overall survival (P=0.037). Multivariate Cox regression analysis showed that miR-20b expression level (HR=2.181, 95% CI: 1.772-9.021, P=0.016) was an independent factor in predicting the overall survival of prostate cancer patients.

CONCLUSION

The present study demonstrated that tissue miR-20b expression level could be a promising biomarker of prognosis in prostate cancer.

The Prospect of Identifying Resistance Mechanisms for Castrate-Resistant Prostate Cancer Using Circulating Tumor Cells: Is Epithelial-to-Mesenchymal Transition a Key Player?

Prostate cancer (PCa) is initially driven by excessive androgen receptor (AR) signaling with androgen deprivation therapy (ADT) being a major therapeutic approach to its treatment. However, the development of drug resistance is a significant limitation on the effectiveness of both first-line and more recently developed second-line ADTs. There is a need then to study AR signaling within the context of other oncogenic signaling pathways that likely mediate this resistance. This review focuses on interactions between AR signaling, the well-known phosphatidylinositol-3-kinase/AKT pathway, and an emerging mediator of these pathways, the Hippo/YAP1 axis in metastatic castrate-resistant PCa, and their involvement in the regulation of epithelial-mesenchymal transition (EMT), a feature of disease progression and ADT resistance. Analysis of these pathways in circulating tumor cells (CTCs) may provide an opportunity to evaluate their utility as biomarkers and address their importance in the development of resistance to current ADT with potential to guide future therapies.

Long non-coding RNA FER1L4 inhibits prostate cancer progression via sponging miR-92a-3p and upregulation of FBXW7

Background

Dysregulation of long non-coding RNAs (lncRNAs) is involved in development of prostate cancer. However, the molecular mechanisms of many lncRNAs in prostate cancer have not been studied yet.

Methods

The lncRNA Fer-1-like protein 4 (FER1L4) expression was explored in prostate tumors and normal prostate tissues by RT-qPCR and bioinformatic analysis. Overexpression of FER1L4 was performed to evaluate its role in prostate cancer cell proliferation and survival. The molecular mechanism of FER1L4 was investigated by dual luciferase reporter assay, RNA pull down assay, western blotting and RT-qPCR.

Results

It was found that FER1L4 was lower in prostate cancer tissues than normal tissues. Higher expression of FER1L4 was associated with prostate cancer tissues of early stage (AJCC stage I/II). Overexpression of FER1L4 inhibited cell proliferation and promoted cell apoptosis in prostate cancer cells. Bioinformatic analysis, RT-qPCR, RNA pull down assay and dual luciferase assay showed that FER1L4 upregulated F-box/WD repeat-containing protein 7 (FBXW7) tumor suppressor via sponging miR-92a-3p. Silencing of FBXW7 reversed the cell phenotypes caused by FER1L4 overexpression in prostate cancer cells.

Conclusion

The data demonstrated that FER1L4, a downregulated lncRNA in prostate cancer, was pivotal for cell proliferation and survival of prostate cancer. The study provided new sights into understanding of the signaling network in prostate cancer and implied that FER1L4 might be a biomarker for patients with prostate cancer.

Carotenoids and their role in cancer prevention

Approximately two of every five people will develop cancer in their lifetime. Dietary modifications are one of the most promising lifestyle changes that can adjust the risk of developing cancer by nearly 40%. Carotenoids are a diverse group of natural pigments and are present in many fruits and vegetables. The data surrounding carotenoids and their potential roles in carcinogenesis have been rapidly growing over the past two decades. This review summarizes the literature surrounding the associations between the most six common carotenoids in the diet and ten of the most commonly diagnosed cancers. In this study, preclinical, epidemiological, and toxicology data were reviewed. Data from these studies suggest that several carotenoids might provide a beneficial impact on reducing carcinogenesis. Further studies are needed to determine the causal relationships between individual carotenoids and cancer incidence and progression. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.

Prognostic value of testosterone for the castration-resistant prostate cancer patients: a systematic review and meta-analysis

INTRODUCTION

This systematic review and meta-analysis aimed to assess the prognostic value of testosterone in patients with castration-resistant prostate cancer (CRPC).

MATERIALS AND METHODS

PubMed, Web of Science, and Scopus databases were systematically searched until December 2019, according to the Preferred Reporting Items for Systemic Review and Meta-analysis statement. The endpoints were progression-free survival (PFS) and overall survival (OS).

RESULTS

We identified 11 articles with 4206 patients for systematic review and nine articles with 4136 patients for meta-analysis. Higher testosterone levels were significantly associated with better OS (pooled HR 0.74, 95% CI 0.58-0.95) and better PFS (pooled HR 0.51, 95% CI 0.30-0.87). Subgroup analyses based on the treatment type revealed that higher testosterone levels were significantly associated with better OS in CRPC patients treated with androgen receptor-targeted agents (ARTAs) (pooled HR 0.64, 95% CI 0.55-0.75), but not in those treated with chemotherapy (pooled HR 0.78, 95% CI 0.53-1.14).

CONCLUSION

This meta-analysis demonstrated that the PFS and OS were significantly greater in patients with CRPC in those with higher testosterone levels than that of those with lower testosterone levels. In the subgroup analyses, lower testosterone levels were a consistently poor prognostic factor for OS in patients treated with ARTAs, but not in those treated with chemotherapy. Therefore, higher testosterone levels could be a useful biomarker to identify patient subgroups in which ARTAs should be preferentially recommended in the CRPC setting.

Non-Steroidal Androgen Receptor Antagonists and Prostate Cancer: A Survey on Chemical Structures Binding this Fast-Mutating Target

The Androgen Receptor (AR) pathway plays a major role in both the pathogenesis and progression of prostate cancer. In particular, AR is chiefly involved in the development of Castration-Resistant Prostate Cancer (CRPC) as well as in the resistance to the secondgeneration AR antagonist enzalutamide, and to the selective inhibitor of cytochrome P450 17A1 (CYP17A1) abiraterone. Several small molecules acting as AR antagonists have been designed and developed so far, also as a result of the ability of cells expressing this molecular target to rapidly develop resistance and turn pure receptor antagonists into ineffective or event detrimental molecules. This review covers a survey of most promising classes of non-steroidal androgen receptor antagonists, also providing insights into their mechanism of action and efficacy in treating prostate cancer.

Comparative Proteome Profiling and Mutant Protein Identification in Metastatic Prostate Cancer Cells by Quantitative Mass Spectrometry-based Proteogenomics

BACKGROUND/AIM

Prostate cancer (PCa) is the most frequent cancer found in males worldwide. The aim of this study was to identify new biomarkers using mutated peptides for the prognosis and prediction of advanced PCa, based on proteogenomics.

MATERIALS AND METHODS

The tryptic peptides were analyzed by tandem mass tag-based quantitative proteomics. Proteogenomics were used to identify mutant peptides as novel biomarkers in advanced PCa.

RESULTS

Using a human database, increased levels of INTS7 and decreased levels of SH3BGRL were found to be associated with the aggressiveness of PCa. Using proteogenomics and a cancer mutation database, 70 mutant peptides were identified in PCa cell lines. Using parallel reaction monitoring, the expression of seven mutant peptides was found to be altered in tumors, amongst which CAPN2 D22E was the most significantly up-regulated mutant peptide in PCa tissues.

CONCLUSION

Altered mutant peptides present in PCa tissue could be used as new biomarkers in advanced PCa.

Incidence of androgen receptor and androgen receptor variant 7 coexpression in prostate cancer

BACKGROUND

Prostate cancer (PRCA) is an androgen-driven disease, where androgens act through the androgen receptor (AR) to induce proliferation and survival of tumor cells. Recently, AR splice variant 7 (ARv7) has been implicated in advanced stages of PRCA and clinical recurrence. With the widespread use of AR-targeted therapies, there has been a rising interest in the expression of full-length AR and ARv7 in PRCA progression and how these receptors, both independently and together, contribute to adverse clinicopathologic outcomes.

METHODS

Despite a multitude of studies measuring the expression levels of AR and ARv7 in PRCA progression, the results have been inconsistent and sometimes contradictory due to technical and analytical discrepancies. To circumvent these inconsistencies, we used an automated multiplexed immunostaining platform for full-length AR and ARv7 in human PRCA samples and objectively quantified expression changes with machine learning-based software. With this technology, we can assess receptor prevalence both independently, and coexpressed, within specific tissue and cellular compartments.

RESULTS

Full-length AR and ARv7 expression increased in epithelial nuclei of metastatic samples compared to benign. Interestingly, a population of cells with undetectable AR persisted through all stages of PRCA progression. Coexpression analyses showed an increase of the double-positive (AR⁺ /ARv7⁺ ) population in metastases compared to benign, and an increase of the double-negative population in PRCA samples compared to benign. Importantly, analysis of clinicopathologic outcomes associated with AR/ARv7 coexpression showed a significant decrease in the double-positive population with higher Gleason score (GS), as well as in samples with recurrence in under 5 years. Conversely, the double-negative population was significantly increased in samples with higher GS and in samples with recurrence in under 5 years.

CONCLUSIONS

Changes in AR and ARv7 coexpression may have prognostic value in PRCA progression and recurrence. A better understanding of the prevalence and clinicopathologic outcomes associated with changes in these receptors' coexpression may provide a foundation for improved diagnosis and therapy for men with PRCA.

Isoquinolinamine FX-9 Exhibits Anti-Mitotic Activity in Human and Canine Prostate Carcinoma Cell Lines

Current therapies are insufficient for metastatic prostate cancer (PCa) in men and dogs. As human castrate-resistant PCa shares several characteristics with the canine disease, comparative evaluation of novel therapeutic agents is of considerable value for both species. Novel isoquinolinamine FX-9 exhibits antiproliferative activity in acute lymphoblastic leukemia cell lines but has not been tested yet on any solid neoplasia type. In this study, FX-9′s mediated effects were characterized on two human (PC-3, LNCaP) and two canine (CT1258, 0846) PCa cell lines, as well as benign solid tissue cells. FX-9 significantly inhibited cell viability and induced apoptosis with concentrations in the low micromolar range. Mediated effects were highly comparable between the PCa cell lines of both species, but less pronounced on non-malignant chondrocytes and fibroblasts. Interestingly, FX-9 exposure also leads to the formation and survival of enlarged multinucleated cells through mitotic slippage. Based on the results, FX-9 acts as an anti-mitotic agent with reduced cytotoxic activity in benign cells. The characterization of FX-9-induced effects on PCa cells provides a basis for in vivo studies with the potential of valuable transferable findings to the benefit of men and dogs.

Network-based analysis of prostate cancer cell lines reveals novel marker gene candidates associated with radioresistance and patient relapse

Radiation therapy is an important and effective treatment option for prostate cancer, but high-risk patients are prone to relapse due to radioresistance of cancer cells. Molecular mechanisms that contribute to radioresistance are not fully understood. Novel computational strategies are needed to identify radioresistance driver genes from hundreds of gene copy number alterations. We developed a network-based approach based on lasso regression in combination with network propagation for the analysis of prostate cancer cell lines with acquired radioresistance to identify clinically relevant marker genes associated with radioresistance in prostate cancer patients. We analyzed established radioresistant cell lines of the prostate cancer cell lines DU145 and LNCaP and compared their gene copy number and expression profiles to their radiosensitive parental cells. We found that radioresistant DU145 showed much more gene copy number alterations than LNCaP and their gene expression profiles were highly cell line specific. We learned a genome-wide prostate cancer-specific gene regulatory network and quantified impacts of differentially expressed genes with directly underlying copy number alterations on known radioresistance marker genes. This revealed several potential driver candidates involved in the regulation of cancer-relevant processes. Importantly, we found that ten driver candidates from DU145 (ADAMTS9, AKR1B10, CXXC5, FST, FOXL1, GRPR, ITGA2, SOX17, STARD4, VGF) and four from LNCaP (FHL5, LYPLAL1, PAK7, TDRD6) were able to distinguish irradiated prostate cancer patients into early and late relapse groups. Moreover, in-depth in vitro validations for VGF (Neurosecretory protein VGF) showed that siRNA-mediated gene silencing increased the radiosensitivity of DU145 and LNCaP cells. Our computational approach enabled to predict novel radioresistance driver gene candidates. Additional preclinical and clinical studies are required to further validate the role of VGF and other candidate genes as potential biomarkers for the prediction of radiotherapy responses and as potential targets for radiosensitization of prostate cancer.

Prostate cancer cell lines represent an important model system to characterize molecular alterations that contribute to radioresistance, but irradiation can cause deletions and amplifications of DNA segments that affect hundreds of genes. This in combination with the small number of cell lines that are usually considered does not allow a straight-forward identification of driver genes by standard statistical methods. Therefore, we developed a network-based approach to analyze gene copy number and expression profiles of such cell lines enabling to identify potential driver genes associated with radioresistance of prostate cancer. We used lasso regression in combination with a significance test for lasso to learn a genome-wide prostate cancer-specific gene regulatory network. We used this network for network flow computations to determine impacts of gene copy number alterations on known radioresistance marker genes. Mapping to prostate cancer samples and additional filtering allowed us to identify 14 driver gene candidates that distinguished irradiated prostate cancer patients into early and late relapse groups. In-depth literature analysis and wet-lab validations suggest that our method can predict novel radioresistance driver genes. Additional preclinical and clinical studies are required to further validate these genes for the prediction of radiotherapy responses and as potential targets to radiosensitize prostate cancer.

IS TESTOSTERONE PROGNOSTIC IN PROSTATE CANCER TREATMENT? THE UROLOGICAL STANDPOINT

Prostate cancer (PC) is known as an androgen-dependent tumor with testosterone as its natural growth factor, its action is mediated by the androgen receptor (AR) important for the biology and progression of PC. During aging a progressive decline in testosterone levels begins, caused by disability of aged Leydig cells to produce testosterone in response to luteinizing hormone. Surgical treatment of PC can influence the hypothalamic-pituitary-gonadal axis with less impact on it compared to patients treated with radiation. Patients with pre-operative low baseline testosterone level had mean Gleason score higher and AR expression was higher; significantly lower testosterone levels were recorded in patients with lymph node metastases. But some data are conflicting, and some results are opposite to those mentioned before. These data show that there is no significant association between all sex hormone in men and lethal PC or total mortality. In patients with metastatic PC, results showed that elevation of baseline androstenedione levels was predictive of prostate-specific antigen (PSA) response; higher baseline androstenedione levels were associated with an improved overall survival. In these patients, the relationship between serum testosterone and PC prognosis varies in different clinical settings and according to androgen deprivation therapy administration.

Aberrant KIF20A Expression Is Associated with Adverse Clinical Outcome and Promotes Tumor Progression in Prostate Cancer

Purpose

KIF20A is essential in the process of spindle assembly and cytokinesis regulation. The role of KIF20A during tumorigenesis and tumor development has been well studied in several cancers. But the association between the KIF20A clinical role and prostate cancer (PCa) has not been reported yet. In this study, we investigated its potential prognostic effect and its role in progression of prostate cancer.

Methods

Real-time quantitative polymerase chain reaction and Western blots were used to investigate the KIF20A transcription and translation levels in 7 pairs of fresh PCa tissue and adjacent normal prostate tissue. Immunohistochemistry (IHC) was used to investigate the KIF20A protein level in 114 PCa tissue samples. Bioinformatics analysis was performed to analyze the effect of KIF20A in oncologic prognosis in PCa patients. MTT assay, transwell assay, and colony formation assay in vitro and tumor formation assay in vivo were performed to evaluate the biological behavior of KIF20A in prostate cancer.

Results

KIF20A was significantly elevated in tumor tissue compared with normal prostate tissue at both the mRNA and the protein level. High expression of KIF20A at the protein level was correlated with adverse clinicopathological features. Bioinformatics analysis showed that the high KIF20A expression group has a poor biochemical recurrence- (BCR-) free survival. Knocking down KIF20A suppressed the proliferation, migration, and invasion of the prostate cancer cell both in vitro and in vivo.

Conclusions

Our data demonstrated that the high expression of KIF20A was associated with poor clinical outcome and targeting KIF20A could reduce proliferation, migration, and invasion of the prostate cancer cell, indicating that KIF20A might be a potential prognostic and therapeutic target for PCa patients.

BRD4 Regulates Metastatic Potential of Castration-Resistant Prostate Cancer through AHNAK

The inevitable progression of advanced prostate cancer to castration resistance, and ultimately to lethal metastatic disease, depends on primary or acquired resistance to conventional androgen deprivation therapy (ADT) and accumulated resistance strategies to evade androgen receptor (AR) suppression. In prostate cancer cells, AR adaptations that arise in response to ADT are not singular, but diverse, and include gene amplification, mutation, and even complete loss of receptor expression. Collectively, each of these AR adaptations contributes to a complex, heterogeneous, ADT-resistant tumor. Here, we examined prostate cancer cell lines that model common castration-resistant prostate cancer (CRPC) subtypes, each with different AR composition, and focused on novel regulators of tumor progression, the Bromodomain and Extraterminal (BET) family of proteins. We found that BRD4 regulates cell migration across all models of CRPC, regardless of aggressiveness and AR status, whereas BRD2 and BRD3 only regulate migration and invasion in less aggressive models that retain AR expression or signaling. BRD4, a coregulator of gene transcription, controls migration and invasion through transcription of AHNAK, a large scaffolding protein linked to promotion of metastasis in a diverse set of cancers. Furthermore, treatment of CRPC cell lines with low doses of MZ1, a small-molecule, BRD4-selective degrader, inhibits metastatic potential. Overall, these results reveal a novel BRD4-AHNAK pathway that may be targetable to treat metastatic CRPC (mCRPC). IMPLICATIONS: BRD4 functions as the dominant regulator of CRPC cell migration and invasion through direct transcriptional regulation of AHNAK, which together offer a novel targetable pathway to treat metastatic CRPC.Visual Overview: http://mcr.aacrjournals.org/content/molcanres/17/8/1627/F1.large.jpg.

STAT5a/b Deficiency Delays, but does not Prevent, Prolactin-Driven Prostate Tumorigenesis in Mice

The canonical prolactin (PRL) Signal Transducer and Activator of Transcription (STAT) 5 pathway has been suggested to contribute to human prostate tumorigenesis via an autocrine/paracrine mechanism. The probasin (Pb)-PRL transgenic mouse models this mechanism by overexpressing PRL specifically in the prostate epithelium leading to strong STAT5 activation in luminal cells. These mice exhibit hypertrophic prostates harboring various pre-neoplastic lesions that aggravate with age and accumulation of castration-resistant stem/progenitor cells. As STAT5 signaling is largely predominant over other classical PRL-triggered pathways in Pb-PRL prostates, we reasoned that Pb-Cre recombinase-driven genetic deletion of a floxed Stat5a/b locus should prevent prostate tumorigenesis in so-called Pb-PRL^ΔSTAT5 mice. Anterior and dorsal prostate lobes displayed the highest Stat5a/b deletion efficiency with no overt compensatory activation of other PRLR signaling cascade at 6 months of age; hence the development of tumor hallmarks was markedly reduced. Stat5a/b deletion also reversed the accumulation of stem/progenitor cells, indicating that STAT5 signaling regulates prostate epithelial cell hierarchy. Interestingly, ERK1/2 and AKT, but not STAT3 and androgen signaling, emerged as escape mechanisms leading to delayed tumor development in aged Pb-PRL^ΔSTAT5 mice. Unexpectedly, we found that Pb-PRL prostates spontaneously exhibited age-dependent decline of STAT5 signaling, also to the benefit of AKT and ERK1/2 signaling. As a consequence, both Pb-PRL and Pb-PRL^ΔSTAT5 mice ultimately displayed similar pathological prostate phenotypes at 18 months of age. This preclinical study provides insight on STAT5-dependent mechanisms of PRL-induced prostate tumorigenesis and alternative pathways bypassing STAT5 signaling down-regulation upon prostate neoplasia progression.

STAT3 Post-Translational Modifications Drive Cellular Signaling Pathways in Prostate Cancer Cells

STAT3 is an oncoprotein overexpressed in different types of tumors, including prostate cancer (PCa), and its activity is modulated by a variety of post-translational modifications (PTMs). Prostate cancer represents the most common cancer diagnosed in men, and each phase of tumor progression displays specific cellular conditions: inflammation is predominant in tumor’s early stage, whereas oxidative stress is typical of clinically advanced PCa. The aim of this research is to assess the correspondence between the stimulus-specificity of STAT3 PTMs and definite STAT3-mediated transcriptional programs, in order to identify new suitable pharmacological targets for PCa treatment. Experiments were performed on less-aggressive LNCaP and more aggressive DU-145 cell lines, simulating inflammatory and oxidative-stress conditions. Cellular studies confirmed pY705-STAT3 as common denominator of all STAT3-mediated signaling. In addition, acK685-STAT3 was found in response to IL-6, whereas glutC328/542-STAT3 and pS727-STAT3 occurred upon tert-butyl hydroperoxyde (tBHP) treatment. Obtained results also provided evidence of an interplay between STAT3 PTMs and specific protein interactors such as P300 and APE1/Ref-1. In accordance with these outcomes, mRNA levels of STAT3-target genes seemed to follow the differing STAT3 PTMs. These results highlighted the role of STAT3 and its PTMs as drivers in the progression of PCa.

Identification of LIMK2 as a therapeutic target in castration resistant prostate cancer

This study identified LIMK2 kinase as a disease-specific target in castration resistant prostate cancer (CRPC) pathogenesis, which is upregulated in response to androgen deprivation therapy, the current standard of treatment for prostate cancer. Surgical castration increases LIMK2 expression in mouse prostates due to increased hypoxia. Similarly, human clinical specimens showed highest LIMK2 levels in CRPC tissues compared to other stages, while minimal LIMK2 was observed in normal prostates. Most notably, inducible knockdown of LIMK2 fully reverses CRPC tumorigenesis in castrated mice, underscoring its potential as a clinical target for CRPC. We also identified TWIST1 as a direct substrate of LIMK2, which uncovered the molecular mechanism of LIMK2-induced malignancy. TWIST1 is strongly associated with CRPC initiation, progression and poor prognosis. LIMK2 increases TWIST1 mRNA levels upon hypoxia; and stabilizes TWIST1 by direct phosphorylation. TWIST1 also stabilizes LIMK2 by inhibiting its ubiquitylation. Phosphorylation-dead TWIST1 acts as dominant negative and fully prevents EMT and tumor formation in vivo, thereby highlighting the significance of LIMK2-TWIST1 signaling axis in CRPC. As LIMK2 null mice are viable, targeting LIMK2 should have minimal collateral toxicity, thereby improving the overall survival of CRPC patients.

IL-1 induces p62/SQSTM1 and autophagy in ERα+ /PR+ BCa cell lines concomitant with ERα and PR repression, conferring an ERα- /PR- BCa-like phenotype

Estrogen receptor α (ERα)^low/- tumors are associated with breast cancer (BCa) endocrine resistance, where ERα low tumors show a poor prognosis and a molecular profile similar to triple negative BCa tumors. Interleukin-1 (IL-1) downregulates ERα accumulation in BCa cell lines, yet the cells can remain viable. In kind, IL-1 and ERα show inverse accumulation in BCa patient tumors and IL-1 is implicated in BCa progression. IL-1 represses the androgen receptor hormone receptor in prostate cancer cells concomitant with the upregulation of the prosurvival, autophagy-related protein, Sequestome-1 (p62/SQSTM1; hereinafter, p62); and given their similar etiology, we hypothesized that IL-1 also upregulates p62 in BCa cells concomitant with hormone receptor repression. To test our hypothesis, BCa cell lines were exposed to conditioned medium from IL-1-secreting bone marrow stromal cells (BMSCs), IL-1, or IL-1 receptor antagonist. Cells were analyzed for the accumulation of ERα, progesterone receptor (PR), p62, or the autophagosome membrane protein, microtubule-associated protein 1 light chain 3 (LC3), and for p62-LC3 interaction. We found that IL-1 is sufficient to mediate BMSC-induced ERα and PR repression, p62 and autophagy upregulation, and p62-LC3 interaction in ERα⁺ /PR⁺ BCa cell lines. However, IL-1 does not significantly elevate the high basal p62 accumulation or high basal autophagy in the ERα^- /PR^- BCa cell lines. Thus, our observations imply that IL-1 confers a prosurvival ERα^- /PR^- molecular phenotype in ERα⁺ /PR⁺ BCa cells that may be dependent on p62 function and autophagy and may underlie endocrine resistance.

Exercise medicine for advanced prostate cancer

PURPOSE OF REVIEW

Exercise is a provocative medicine, known for its preventive, complimentary and rehabilitative role in the management of cancer. Impressively, exercise is also emerging as a synergistic and targeted medicine to enhance symptom control, modulate tumour biology and delay disease progression, with the potential to increase overall survival. Given the complex clinical presentation of advanced prostate cancer patients and their omnipresent comorbidities, this review describes the current and potential role of exercise medicine in advanced prostate cancer.

RECENT FINDINGS

Exercise has been shown to be safe, feasible and effective for advanced prostate cancer patients, inclusive of patients with bone metastases; a previously excluded population due to patient and clinician fear of adverse events. Preclinical data provide insight into the ability of exercise to modulate cancer-specific outcomes, may synergistically increase the potency of chemotherapy and radiotherapy and may endogenously and/or mechanically suppress tumour formation, growth and invasion in visceral and skeletal tissue. Epidemiological studies have also shown an association between physical activity and increased survival.

SUMMARY

Exercise oncology is rapidly evolving, with impressive possibilities that may directly improve patient outcomes in advanced prostate cancer. Research must focus on translating preclinical trials into human clinical trials and investigate the direct effect of exercise on overall survival.

MicroRNA-126 inhibits proliferation and metastasis in prostate cancer via regulation of ADAM9

The aberrant expression of microRNAs (miRs) has been identified to serve a crucial role in tumor progression. The present study aimed to evaluate the role of miR-126 in human prostate cancer (PCa). Firstly, miR-126 expression in prostate cancer tissues and cell lines was analyzed. A luciferase reporter assay and a rescue assay were performed, which identified ADAM metalloproteinase domain 9 (ADAM9) as the target gene of miR-126. Subsequently, Kaplan-Meier and log-rank analyses were used to investigate the association between ADAM9 expression and PCa prognosis. The results revealed that miR-126 expression was significantly downregulated in PCa tissues and cell lines. miR-126 overexpression was demonstrated to reduce PCa cell proliferation and metastasis, and to reverse the epithelial-mesenchymal transition process in vitro. In addition, as the target gene of miR-126, the upregulation of ADAM9 reestablished cell functions, including cell proliferation, migration and invasion. Patients with high ADAM9 expression levels exhibited a shorter biochemical recurrence-free survival time. In summary, miR-126 serves a role in the proliferation and metastasis of PCa cells, indicating that miR-126 and ADAM9 may represent potential biomarkers in the progression of advanced PCa, in addition to therapeutic targets.

The Expression of Androgen Receptor and Its Variants in Human Prostate Cancer Tissue according to Disease Status, and Its Prognostic Significance

Purpose

To evaluate changes in the expression of androgen receptor (AR) and its variants (ARVs) in human prostate cancer (PCa) tissues according to disease status, and its prognostic significance following radical prostatectomy (RP).

Materials and Methods

A total of 282 PCa cases were evaluated, which included 252 localized PCa, 8 metastatic castration resistant prostate cancer (CRPC), and 22 benign prostatic hyperplasia (BPH) cases. Samples were collected from patients who underwent RP or transurethral resection and were stored in ethically approved tissue banks. Quantitative real-time polymerase chain reaction, Western blotting, and immunohistochemistry were performed for AR and ARVs. Each tissue was confirmed as cancerous (greater than 80%) using hematoxylin and eosin staining. AR and ARVs expression was compared according to disease status. The biochemical recurrence free survival (BCRFS) rates in men with localized PCa was analyzed according to AR and ARV7 expression using the Kaplan-Meier curve.

Results

Only 58 of the 252 localized PCa were included in the analysis because of insufficient cancer tissue. AR and ARV7 mRNA expression was higher in the CRPC tissue than in the localized PCa tissue (p=0.025, p=0.002, respectively). In localized PCa tissue, high AR mRNA and protein level was associated with a low BCRFS rate (log-ranked, p=0.019, p<0.001, respectively).

Conclusions

Overall AR and ARV7 mRNA expression levels were increased in CRPC tissues compared to localized PCa and BPH tissues. High AR protein and mRNA expression in the tumor tissue may be considered a predictive factor of BCRFS following RP.

Cell-Free DNA Modification Dynamics in Abiraterone Acetate-Treated Prostate Cancer Patients

Purpose: Primary resistance to abiraterone acetate (AA), a key medication for the treatment of metastatic castration-resistant prostate cancer, occurs in 20% to 40% of patients. We aim to identify predictive biomarkers for AA-treatment response and understand the mechanisms related to treatment resistance.Experimental Design: We used the Infinium Human Methylation 450K BeadChip to monitor modification profiles of cell-free circulating DNA (cfDNA) in 108 plasma samples collected from 33 AA-treated patients.Results: Thirty cytosines showed significant modification differences (FDR Q < 0.05) between AA-sensitive and AA-resistant patients during the treatment, of which 21 cytosines were differentially modified prior to treatment. In addition, AA-sensitive patients, but not AA-resistant patients, lost interindividual variation of cfDNA modification shortly after starting AA treatment, but such variation returned to initial levels in the later phases of treatment.Conclusions: Our findings provide a list of potential biomarkers for predicting AA-treatment response, highlight the prognostic value of using cytosine modification variance as biomarkers, and shed new insights into the mechanisms of prostate cancer relapse in AA-sensitive patients. Clin Cancer Res; 24(14); 3317-24. ©2018 AACR.

Phosphorylation of androgen receptors at serine 515 is a potential prognostic marker for triple negative breast cancer

1.7 million cases of breast cancer are diagnosed every year with 522,000 deaths. Molecular classifications of breast cancer have resulted in improved treatments. However, treatments for triple negative breast cancer (TNBC) are lacking. Analysis of molecular targets for TNBC is a priority. One potential candidate is androgen receptor (AR) phosphorylation. This study assessed the role of AR phosphorylation at ser81/ser515 and their two upstream effectors, cyclin-dependent kinase 1 (pCDK1) and extracellular-regulated kinase 1/2 (pERK1/2) in 332 ductal breast cancer patients by immunohistochemistry.

pERK1/2 combined with AR-515 associated with improved cancer-specific survival (CSS, p = 0.038), decreased size (p = 0.001), invasive grade (p < 0.001), necrosis (p = 0.003), b-lymphocytes (p = 0.020), molecular subtype (p < 0.001) and estrogen receptor (ER)/progesterone receptor (PR)-status (p < 0.001). The cohort was therefore stratified into ER+ve and ER-ve patients. In ER+ve tumours, pERK1/2 combined with AR-515 associated with improved CSS (p = 0.038), smaller size (p = 0.004), invasive grade (p = 0.001), decreased b-lymphocytes (p = 0.013) and increased plasma cells (p = 0.048). In contrast, in TNBC patients, phosphorylation of AR-515 associated with poorer CSS (p = 0.007). pERK1/2 combined with AR-515 associated with decreased inflammation (p = 0.003), increased tumour stroma (p = 0.003) and tumour budding (p = 0.011), with trends towards decrease CSS (p = 0.065) and macrophage levels (p = 0.093).

In Conclusions, AR-515 may be an important regulator of inflammation in breast cancer potential via ERK1/2 phosphorylation. AR-515 is a potential prognostic marker and therapeutic target for TNBC.

Prostate cancer chemoprevention by natural agents: Clinical evidence and potential implications

Prostate cancer (PCa) is the most common non-skin cancer and the second leading cause of cancer-related deaths in American men. Due to its long latency period, PCa is considered as an ideal cancer type for chemopreventive interventions. Chemopreventive agents include various natural or synthetic agents that prevent or delay cancer development, progression and/or recurrence. Pre-clinical studies suggest that many natural products and dietary agents have chemopreventive properties. However, a limited number of these agents have been tested in clinical trials, with varying success. In this review, we have discussed the available clinical studies regarding the efficacy of natural chemopreventive agents against PCa, including tea polyphenols, selenium, soy proteins, vitamins and resveratrol. We have also provided a discussion on the clinical challenges and opportunities for the potential use of chemopreventive agents against PCa. Based on available literature, it appears that the variable outcomes of the chemopreventive clinical studies necessitate a need for additional studies with more rigorous designs and methodical interpretations in order to measure the potential of the natural agents against PCa.

Clinical applications of the CellSearch platform in cancer patients

The CellSearch® system (CS) enables standardized enrichment and enumeration of circulating tumor cells (CTCs) that are repeatedly assessable via non-invasive "liquid biopsy". While the association of CTCs with poor clinical outcome for cancer patients has clearly been demonstrated in numerous clinical studies, utilizing CTCs for the identification of therapeutic targets, stratification of patients for targeted therapies and uncovering mechanisms of resistance is still under investigation. Here, we comprehensively review the current benefits and drawbacks of clinical CTC analyses for patients with metastatic and non-metastatic tumors. Furthermore, the review focuses on approaches beyond CTC enumeration that aim to uncover therapeutically relevant antigens, genomic aberrations, transcriptional profiles and epigenetic alterations of CTCs at a single cell level. This characterization of CTCs may shed light on the heterogeneity and genomic landscapes of malignant tumors, an understanding of which is highly important for the development of new therapeutic strategies.

Immunogenetics of prostate cancer: a still unexplored field of study

The immune system is a double-edged sword with regard to the prostate cancer (PCa) battle. Immunogenetics, the study of the potential role of immune-related polymorphisms, is taking its first steps in the treatment of this malignancy. This review summarizes the most recent papers addressing the potential of immunogenetics in PCa, reporting immune-related polymorphisms associated with tumor aggressiveness, treatment toxicity and patients' prognosis. With some peculiarities, RNASEL, IL-6, IL-10, IL-1β and MMP7 have arisen as the most significant biomarkers in PCa treatment and management, having a potential clinical role. Validation prospective clinical studies are required to translate immunogenetics into precision treatment of PCa.

Baicalein suppresses the androgen receptor (AR)-mediated prostate cancer progression via inhibiting the AR N-C dimerization and AR-coactivators interaction

BACKGROUND

Androgen receptor (AR) plays a critical role in prostate cancer (PCa) development and progression. Androgen deprivation therapy with antiandrogens to reduce androgen biosynthesis or prevent androgens from binding to AR are widely used to suppress AR-mediated PCa growth. However, most of ADT may eventually fail with development of the castration resistance after 12-24 months. Here we found that a natural product baicalein can effectively suppress the PCa progression via targeting the androgen-induced AR transactivation with little effect to AR protein expression.

METHODS

PCa cells including LNCaP, CWR22Rv1, C4-2, PC-3, and DU145, were treated with baicalein and luciferase assay was used to evaluate their effect on the AR transactivation. Cell growth and IC50 were determined by MTT assay after 48 hrs treatment. RT-PCR was used to evaluate the mRNA levels of AR target genes including PSA, TMPRSS2, and TMEPA1. Western blot was used to determine AR and PSA protein expression.

RESULTS

The natural product of baicalein can selectively inhibit AR transactivation with little effect on the other nuclear receptors, including ERα, and GR. At a low concentration, 2.5 μM of baicalein effectively suppresses the growth of AR-positive PCa cells, and has little effect on AR-negative PCa cells. Mechanism dissection suggest that baicalein can suppress AR target genes (PSA, TMPRSS2, and TMEPA1) expression in both androgen responsive LNCaP cells and castration resistant CWR22Rv1 cells, that may involve the inhibiting the AR N/C dimerization and AR-coactivators interaction.

CONCLUSIONS

Baicalein may be developed as an effective anti-AR therapy via its ability to inhibit AR transactivation and AR-mediated PCa cell growth.

A novel deubiquitinase inhibitor b-AP15 triggers apoptosis in both androgen receptor-dependent and -independent prostate cancers

Prostate cancer (PCa) remains a leading cause of cancer-related death in men. Especially, a subset of patients will eventually progress to the metastatic castrate-resistant prostate cancer (CRPC) which is currently incurable. Deubiquitinases (DUBs) associated with the 19S proteasome regulatory particle are increasingly emerging as significant therapeutic targets in numerous cancers. Recently, a novel small molecule b-AP15 is identified as an inhibitor of the USP14/UCHL5 (DUBs) of the 19S proteasome, resulting in cell growth inhibition and apoptosis in several human cancer cell lines. Here, we studied the therapeutic effect of b-AP15 in PCa, and our results indicate that (i) b-AP15 decreases viability, proliferation and triggers cytotoxicity to both androgen receptor-dependent and -independent PCa cells in vitro and in vivo, associated with caspase activation, inhibition of mitochondria function, increased reactive oxygen species (ROS) generation and endoplasmic reticulum (ER) stress; (ii) pan-caspase inhibitor z-VAD-FMK and ROS scavenger N-acetyl-L-cysteine (NAC) efficiently block apoptosis but not proteasome inhibition induced by exposure of b-AP15; (iii) treatment with b-AP15 in androgen-dependent prostate cancer (ADPC) cells down-regulates the expression of androgen receptor (AR), which is degraded via the ubiquitin proteasome system. Hence, the potent anti-tumor effect of b-AP15 on both androgen receptor-dependent and -independent PCa cells identifies a new promising therapeutic strategy for prostate cancer.