The development of androgen-independent prostate cancer

The Multifaceted Role of Aldehyde Dehydrogenases in Prostate Cancer Stem Cells

Cancer stem cells (CSCs) are the only tumor cells possessing self-renewal and differentiation properties, making them an engine of tumor progression and a source of tumor regrowth after treatment. Conventional therapies eliminate most non-CSCs, while CSCs often remain radiation and drug resistant, leading to tumor relapse and metastases. Thus, targeting CSCs might be a powerful tool to overcome tumor resistance and increase the efficiency of current cancer treatment strategies. The identification and isolation of the CSC population based on its high aldehyde dehydrogenase activity (ALDH) is widely accepted for prostate cancer (PCa) and many other solid tumors. In PCa, several ALDH genes contribute to the ALDH activity, which can be measured in the enzymatic assay by converting 4, 4-difluoro-4-bora-3a, 4a-diaza-s-indacene (BODIPY) aminoacetaldehyde (BAAA) into the fluorescent product BODIPY-aminoacetate (BAA). Although each ALDH isoform plays an individual role in PCa biology, their mutual functional interplay also contributes to PCa progression. Thus, ALDH proteins are markers and functional regulators of CSC properties, representing an attractive target for cancer treatment. In this review, we discuss the current state of research regarding the role of individual ALDH isoforms in PCa development and progression, their possible therapeutic targeting, and provide an outlook for the future advances in this field.

miRNAs and androgen deprivation therapy for prostate cancer

Androgen deprivation therapy (ADT) is mainly used for the treatment of advanced, metastatic or recurrent prostate cancer (PCa). However, patients progress to ADT resistance and castration-resistant prostate cancer (CRPC) with a poor prognosis. Reliable validated markers of ADT resistance with proven clinical utility are necessary for timely correction of the therapy as well as for improvement of patient quality of life. MiRNAs involved in the ADT response and CRPC development via multiple mechanisms may act as biomarkers for patient outcomes. Available data on miRNAs associated with the ADT response (resistance and sensitivity) are summarized and analyzed in the manuscript, including analyses using bioinformatics resources. Molecular targets of miRNAs, as well as reciprocal relations between miRNAs and their targets, were studied using different databases. Special attention was dedicated to the mechanisms of ADT resistance and CRPC development, including testosterone, PI3K-AKT, VEGF pathways and associated genes. Several different approaches can be used to search for miRNAs associated with the ADT response, each of which focuses on the associated set of miRNAs - potential markers of ADT. The intersection of these approaches and combined analysis allowed us to select the most promising miRNA markers of the ADT response. Meta-analysis of the current data indicated that the selected 5 miRNAs (miRNAs - 125b, miR-21, miR-23b, miR-27b and miR-221) and 14 genes are involved in the regulation of key processes of CRPC development and represent the most promising predictors of the ADT response, further demonstrating their potential in combination therapy for advanced PCa.

Manuscript Title: Analysis of tripartite motif (TRIM) family gene expression in prostate cancer bone metastases

Tripartite motif (TRIM) family proteins are post-translational protein modifiers with E3-ubiquitin ligase activity, thereby involved in various biological processes. The molecular mechanisms driving prostate cancer (PCa) bone metastasis (BM) are incompletely understood, and targetable genetic alterations are lacking in the majority of cases. Therefore, we aimed to explore the expression and potential functional relevance of 71 TRIM members in bone metastatic PCa. We performed transcriptome analysis of all human TRIM family members and 770 cancer-related genes in 29 localized PCa and 30 PCa BM using Nanostring. KEGG, STRING and Ubibrowser were used for further bioinformatic gene correlation and pathway enrichment analyses. Compared to localized tumors, six TRIMs are under-expressed while nine TRIMs are over-expressed in BM. The differentially expressed TRIM proteins are linked to TNF-, TGFβ-, PI3K/AKT- and HIF-1-signaling, and to features such as proteoglycans, platelet activation, adhesion and ECM-interaction based on correlation to cancer-related genes. The identification of TRIM-specific E3-ligase-substrates revealed insight into functional connections to oncogenes, tumor suppressors and cancer-related pathways including androgen receptor- and TGFβ signaling, cell cycle regulation and splicing. In summary, this is the first study that comprehensively and systematically characterizes the expression of all TRIM members in PCa BM. Our results describe post-translational protein modification as an important regulatory mechanism of oncogenes, tumor suppressors, and pathway molecules in PCa progression. Therefore, this study may provide evidence for novel therapeutic targets, in particular for the treatment or prevention of BM.

Association between Alzheimer's disease and risk of cancer: A retrospective cohort study in Shanghai, China

INTRODUCTION

We investigated the association between Alzheimer's disease (AD) and the risk of cancer in the Chinese population.

METHODS

In this retrospective cohort study, multivariate Cox proportional hazard regression analysis was used to determine the correlation between AD and the risk of various cancers, as shown by hazard ratios (HRs) with 95% confidence intervals (CIs).

RESULTS

Of 8097 AD patients, the HR for all subsequent cancers was 0.822 (95% CI, 0.728-0.928; P = .002). Among them, three specific cancers were associated with AD: lung cancer (HR, 0.656; 95% CI, 0.494- 0.871; P = .004), prostate and testicular cancer (HR, 0.414; 95% CI, 0.202-0.847; P = .016), and lymphoma (HR, 2.202; 95% CI, 1.005-4.826; P = .049).

CONCLUSION

Patients with AD might have a lower chance of developing several cancers, including lung cancer and prostate and testicular cancer. Meanwhile, a positive association between AD and a higher incident rate of lymphoma was observed.

PSA response to antiandrogen withdrawal: a systematic review and meta-analysis

BACKGROUND

Antiandrogen withdrawal (AAW) response is the paradoxical decrease in prostate-specific antigen (PSA) following the withdrawal of antiandrogen in patients with advanced prostate cancer. Currently, the reported literature on the proportion of patients exhibiting AAW response and the differences in PSA response between the types of antiandrogens is unclear.

METHODS

This review aimed to explore the PSA response to AAW and to identify if the response depends on the type of antiandrogens. A literature search was performed using databases PubMed, Cochrane and EMBASE with a cut-off date of 23rd of November 2020. Studies reporting on outcomes of AAW and prostate cancer were included. Studies were screened by two reviewers and relevant data extracted. Meta-analysis of outcomes was reported using random-effects and fixed-effects model. A subgroup analysis was performed for type of antiandrogen.

RESULTS

From 450 studies, 23 were included with a total of 1474 patients with advanced prostate cancer were available for further analysis. Overall, 395 (26%) patients had any reduction in PSA levels (95% CI: 20-32%) and 183 (11%) patients had a ≥50% reduction in PSA levels (95% CI: 6-16%). Among the 1212 patients on first-generation antiandrogens, 30% (95% CI: 23-38%) had any PSA decline with 15% patients having a ≥50% PSA decline (95% CI: 8-22%). In contrast, among the 108 patients on second-generation antiandrogens, 7% (95% CI: 0-13%) had any PSA decline and only 1% (95% CI: 0-5%) had a ≥50% PSA decline. Also, among the 154 patients on androgen synthesis inhibitors, 26% (95% CI: 19-33%) had any PSA decline and only 4% (95% CI: 0-13%) had a ≥50% PSA decline.

CONCLUSIONS

One-fourth of patients treated with AAW show a PSA response. However, PSA response to AAW is uncommon with second-generation antiandrogens and androgen synthesis inhibitors. Further research is required to understand the differences in response between the types of antiandrogen.

Can local treatment prolong the sensitivity of metastatic prostate cancer to androgen deprivation or even prevent castration resistance?

PURPOSE

A number of observational clinical studies suggest that prior primary tumor treatment favorably influences the course of metastatic prostate cancer (PCa), but its mechanisms of action are still speculative. Here, we describe the long-lasting sensitivity to various forms of androgen deprivation in patients after radical prostatectomy (RP) for locally advanced PCa as one potential mechanism.

METHODS

A consecutive series of 115 radical prostatectomies after inductive therapy for T4 prostate cancer was re-analyzed, and long-term survival, as well as recurrence patterns and responses to different forms of hormonal manipulation, were assessed.

RESULTS

The estimated biochemical response-free, PCa-specific, and overall survival rates after 200 months were 20%, 65%, and 47% with a median overall survival of 156 months. The majority of patients, although not cured of locally advanced PCa (84/115), showed long-term survival after RP. PCa-specific and overall survival rates of these 84 patients with biochemical recurrence were 61% and 44% at 150 months. Long-term sensitivity to ADT was found to be the main reason for the favorable tumor-specific survival in spite of biochemical recurrence.

CONCLUSIONS

Sensitivity to primary or secondary hormonal manipulation was the main reason for the long-term survival of patients who had not been cured by surgery only. The results suggest that treatment of the primary tumor-bearing prostate delays castration-resistant PCa and enhances the effect of hormonal therapies in a previously unknown manner. The underlying cellular and molecular mechanisms need to be explored in more detailed analyses, which could profoundly impact treatment concepts of locally advanced and metastatic PCa.

MiR-205-driven downregulation of cholesterol biosynthesis through SQLE-inhibition identifies therapeutic vulnerability in aggressive prostate cancer

Prostate cancer (PCa) shows strong dependence on the androgen receptor (AR) pathway. Here, we show that squalene epoxidase (SQLE), an enzyme of the cholesterol biosynthesis pathway, is overexpressed in advanced PCa and its expression correlates with poor survival. SQLE expression is controlled by micro-RNA 205 (miR-205), which is significantly downregulated in advanced PCa. Restoration of miR-205 expression or competitive inhibition of SQLE led to inhibition of de novo cholesterol biosynthesis. Furthermore, SQLE was essential for proliferation of AR-positive PCa cell lines, including abiraterone or enzalutamide resistant derivatives, and blocked transactivation of the AR pathway. Inhibition of SQLE with the FDA approved antifungal drug terbinafine also efficiently blocked orthotopic tumour growth in mice. Finally, terbinafine reduced levels of prostate specific antigen (PSA) in three out of four late-stage PCa patients. These results highlight SQLE as a therapeutic target for the treatment of advanced PCa.

Finasteride for hair loss: a review

BACKGROUND AND OBJECTIVES

Finasteride 1 mg/day is indicated for androgen-dependent conditions such as male androgenetic alopecia (AGA).

METHODS

The literature is comprehensively summarized on the pharmacodynamics, pharmacokinetics, mechanism of action, and metabolism of finasteride. Pairwise and network meta-analyses were performed to assess the efficacy of finasteride reported in clinical trials. The adverse events profile is described along with the post-marketing reports.

RESULTS AND CONCLUSION

Finasteride 1 mg/day significantly increased total hair count compared to placebo after 24 weeks (mean difference = 12.4 hairs/cm², p < .05), and 48 weeks (mean difference = 16.4 hairs/cm², p < .05). The efficacy of the two doses of finasteride (5 mg/day and 1 mg/day) and topical finasteride (1% solution) were not significantly different. The most commonly reported sexual events include erectile dysfunction and decreased libido. Increasing patient complaints and analysis of the FAERS database led to the inclusion of depression in the FDA label in 2011, as men were found to be at a risk of suicide due to the persistent sexual side effects, commonly termed as post-finasteride syndrome. Finasteride is shown to be reasonably tolerated in both men and women; however, patients need to be educated about the possible short- and long-term side-effects.

Obscurin: A multitasking giant in the fight against cancer

Giant obscurins (720-870 kDa), encoded by OBSCN, were originally discovered in striated muscles as cytoskeletal proteins with scaffolding and regulatory roles. Recently though, they have risen to the spotlight as key players in cancer development and progression. Herein, we provide a timely prudent synopsis of the expanse of OBSCN mutations across 16 cancer types. Given the extensive work on OBSCN's role in breast epithelium, we summarize functional studies implicating obscurins as potent tumor suppressors in breast cancer and delve into an in silico analysis of its mutational profile and epigenetic (de)regulation using different dataset platforms and sophisticated computational tools. Lastly, we formally describe the OBSCN-Antisense-RNA-1 gene, which belongs to the long non-coding RNA family and discuss its potential role in modulating OBSCN expression in breast cancer. Collectively, we highlight the escalating involvement of obscurins in cancer biology and outline novel potential mechanisms of OBSCN (de)regulation that warrant further investigation.

Functional analysis of LAT3 in prostate cancer: Its downstream target and relationship with androgen receptor

L‐type amino acid transporter 3 (LAT3, SLC43A1) is abundantly expressed in prostate cancer (PC) and is thought to play an essential role in PC progression through the cellular uptake of essential amino acids. Here, we analyzed the expression, function, and downstream target of LAT3 in PC. LAT3 was highly expressed in PC cells expressing androgen receptor (AR), and its expression was increased by dihydrotestosterone treatment and decreased by bicalutamide treatment. In chromatin immunoprecipitation sequencing of AR, binding of AR to the SLC43A1 region was increased by dihydrotestosterone stimulation. Knockdown of LAT3 inhibited cell proliferation, migration, and invasion, and the phosphorylation of p70S6K and 4EBP‐1. Separase (ESPL1) was identified as a downstream target of LAT3 by RNA sequencing analysis. In addition, immunostaining of prostatectomy specimens was performed. In the multivariate analysis, high expression of LAT3 was an independent prognostic factor for recurrence‐free survival (hazard ratio: 3.24; P = .0018). High LAT3 expression was correlated with the pathological T stage and a high International Society of Urological Pathology grade. In summary, our results suggest that LAT3 plays an important role in the progression of PC.

Suppressive Effect and Molecular Mechanism of Houttuynia cordata Thunb. Extract against Prostate Carcinogenesis and Castration-Resistant Prostate Cancer

Simple Summary

This study explored the chemopreventive effects of Houttuynia cordata Thunb. (HCT) extracts against prostate carcinogenesis in both androgen-sensitive prostate cancer and castration-resistant prostate cancer (CRPC) using the Transgenic Rat for Adenocarcinoma of Prostate (TRAP) model, CRPC xenograft mice, and prostate cancer cell lines. HCT suppressed cell proliferation and stimulated apoptosis via inactivation of AKT/ERK/MAPK in both androgen-sensitive prostate cancer and CRPC cell lines. HCT also inhibited cell migration and EMT phenotypes through the STAT3/Snail/Twist pathway. One of the active compounds of HCT was identified as rutin. Consistent with in vitro study, the incidence of adenocarcinoma in the TRAP model and CRPC tumor growth in the xenograft model were suppressed by induction of apoptosis and inactivation of AKT/ERK/MAPK by HCT intake. Our data demonstrated that HCT attenuated androgen-sensitive prostate cancer and CRPC by mechanisms that may involve inhibition of cell growth and caspase-dependent apoptosis pathways.

Abstract

Houttuynia cordata Thunb. (HCT) is a well-known Asian medicinal plant with biological activities used in the treatment of many diseases including cancer. This study investigated the effects of HCT extract and its ethyl acetate fraction (EA) on prostate carcinogenesis and castration-resistant prostate cancer (CRPC). HCT and EA induced apoptosis in androgen-sensitive prostate cancer cells (LNCaP) and CRPC cells (PCai1) through activation of caspases, down-regulation of androgen receptor, and inactivation of AKT/ERK/MAPK signaling. Rutin was found to be a major component in HCT (44.00 ± 5.61 mg/g) and EA (81.34 ± 5.21 mg/g) in a previous study. Rutin had similar effects to HCT/EA on LNCaP cells and was considered to be one of the active compounds. Moreover, HCT/EA inhibited cell migration and epithelial-mesenchymal transition phenotypes via STAT3/Snail/Twist pathways in LNCaP cells. The consumption of 1% HCT-mixed diet significantly decreased the incidence of adenocarcinoma in the lateral prostate lobe of the Transgenic rat for adenocarcinoma of prostate model. Similarly, tumor growth of PCai1 xenografts was significantly suppressed by 1% HCT treatment. HCT also induced caspase-dependent apoptosis via AKT inactivation in both in vivo models. Together, the results of in vitro and in vivo studies indicate that HCT has inhibitory effects against prostate carcinogenesis and CRPC. This plant therefore should receive more attention as a source for the future development of non-toxic chemopreventive agents against various cancers.

The Role of BCL-2 Proteins in the Development of Castration-resistant Prostate Cancer and Emerging Therapeutic Strategies

The development of androgen resistance in advanced prostate cancer remains a challenging clinical problem. Because androgen deprivation therapy constitutes the backbone of first-line treatments for metastatic prostate cancer, the phenotypic switch from an androgen-dependent to an androgen-independent growth state limits the treatment options for these patients. This critical change from an androgen-dependent to an androgen-independent growth state can be regulated by the B-cell lymphoma gene 2 (BCL-2) family of apoptotic proteins. While the roles of BCL-2 protein family members in the carcinogenesis of prostate cancer have been well-studied, emerging data also delineates their modulation of disease progression to castration-resistant prostate cancer (CRPC). Over the past 2 decades, investigators have sought to describe the mechanisms that underpin this development at the molecular level, yet no recent literature has consolidated these findings in a dedicated review. As new classes of BCL-2 family inhibitors are finding indications for other cancer types, it is time to evaluate how such agents might find stable footing for the treatment of CRPC. Several trials to date have investigated BCL-2 inhibitors as therapeutic agents for CRPC. These therapies include selective BCL-2 inhibitors, pan-BCL-2 inhibitors, and novel inhibitors of MCL-1 and BCL-XL. This review details the research regarding the role of BCL-2 family members in the pathogenesis of prostate cancer and contextualizes these findings within the contemporary landscape of prostate cancer treatment.

Androgen receptor variant shows heterogeneous expression in prostate cancer according to differentiation stage

Quantitation of androgen receptor variant (AR-V) expression in circulating tumor cells (CTCs) from patients with metastatic castration-resistant prostate cancer (mCRPC) has great potential for treatment customization. However, the absence of a uniform CTC isolation platform and consensus on an analytical assay has prevented the incorporation of these measurements in routine clinical practice. Here, we present a single-CTC sensitive digital droplet PCR (ddPCR) assay for the quantitation of the two most common AR-Vs, AR-V7, and AR-v567es, using antigen agnostic CTC enrichment. In a cohort of 29 mCRPC patients, we identify AR-V7 in 66% and AR-v567es in 52% of patients. These results are corroborated using another gene expression platform (NanoString^TM) and by analysis of RNA-Seq data from patients with mCRPC (SU2C- PCF Dream Team). We next quantify AR-V expression in matching EpCAM-positive vs EpCAM-negative CTCs, as EpCAM-based CTC enrichment is commonly used. We identify lower AR-V prevalence in the EpCAM-positive fraction, suggesting that EpCAM-based CTC enrichment likely underestimates AR-V prevalence. Lastly, using single CTC analysis we identify enrichment for AR-v567es in patients with neuroendocrine prostate cancer (NEPC) indicating that AR-v567es may be involved in lineage plasticity, which warrants further mechanistic interrogation.

Ada Gjyrezi et al. show that ddPCR can be used to accurately measure androgen receptor variant (AR-V) expression levels in single circulating tumor cells (CTCs) from prostate cancer patients. They show that current methods for isolating CTCs tend to underestimate the prevalence of AR-V and that a specific variant, AR-v567es, could be potentially used as a biomarker for an aggressive subtype of prostate cancer.

Atorvastatin Enhances Inhibitory Effects of Irradiation on Tumor Growth by Reducing MSH2 Expression both in Prostate Cancer Cells and Xenograft Tumor Models

BACKGROUND

Prostate cancer (PCa) is the fourth most common tumor in males.

OBJECTIVE

To investigate effects of atorvastatin (AS) on PCa cells proliferation and clarify the associated mechanisms.

METHODS

PCa cell lines were cultured and treated with irradiation (IR) (4 Gy), AS (6 μg/ml), transfected with Bcl-2 siRNA, and then divided into different groups. Xenograft tumor mouse model was established. Bcl-2 and MSH2 gene transcription and protein expression were evaluated using RT-PCR assay and western blot assay. Plate clone formation assay was employed to examine colony formation. MTT assay was used to detect cell viabilities. Flow cytometry analysis was utilized to verify apoptosis. Co-immunoprecipitation and immuno-fluorescence assay were used to identify interaction between Bcl-2 and MSH2.

RESULTS

IR significantly reduced colony formation, enhanced Bcl-2 and reduced MSH2 gene transcription in PCa cells compared to un-treated cells (p<0.05). AS significantly strengthened radio-therapeutic effects of IR on colony formation, decreased cell apoptosis and increased Bcl-2 gene transcription/protein expression in PCa cells compared to single IR treatment cells (p<0.05). AS combining IR down-regulated MSH2 gene transcription/protein expression in PCa cells compared to single IR treatment cells (p<0.05). Bcl-2 interacted with MSH2 both in PCa cells and tumor tissues administrating with AS. AS enhanced reductive effects of IR on tumor size of Xenograft tumor mice.

CONCLUSION

Atorvastatin administration enhanced inhibitory effects of IR either on PCa cells or on tumor size of Xenograft tumor mice. The inhibitory effects of atorvastatin were mediated by reducing MSH2 expression and triggering interaction between Bcl-2 and MSH2, both in vitro and in vivo levels.

Qi Ling Inhibits Progression of Androgen-Independent Prostate Cancer via Negative Regulation of TRIM66/HP1γ/AR Axis

AIM

This study aimed to understand the molecular mechanism underlying the therapeutic effect of Qi Ling (QL) against androgen-independent prostate cancer.

METHODS

The relative expression of TRIM66 in prostate tumor was interrogated by microarray. Real-time polymerase chain reaction and Western blotting were performed to determine the transcript abundances and protein expressions of TRIM66, HP1γ, AR, c-Myc, and GAPDH. Cell proliferation and apoptosis were analyzed by cell counting kit-8 method and flow cytometry. The regulatory action of c-Myc on TRIM66 was interrogated with luciferase reporter plasmid and the direct binding was demonstrated by chromatin immunoprecipitation. The secretory prostate-specific antigen was quantified by enzyme-linked immunosorbent assay.

RESULTS

TRIM66 was aberrantly overexpressed in prostate cancer and associated with unfavorable prognosis. TRIM66/HP1γ/AR was upregulated during the androgen-independent transition in hormone-deprived medium. The TRIM66 level positively linked to cell proliferation and negatively linked to cell apoptosis in androgen-independent prostate cancer cells. QL treatment specifically inhibited c-Myc and therefore directly downregulated TRIM66 via binding to its promoter. Ectopic introduction of TRIM66 significantly reversed the anti-tumor effects of QL against androgen-independent prostate cancer.

CONCLUSION

Our study uncovered the importance of downregulated TRIM66/HP1γ/AR signaling in mediating the anti-tumor properties of QL.

AR-V7 in Metastatic Prostate Cancer: A Strategy beyond Redemption

Metastatic prostate cancer is the most common cancer in males and the fifth cause of cancer mortality worldwide. Despite the major progress in this field, leading to the approval of novel anti-androgens, the prognosis is still poor. A significant number of patients acquire an androgen receptor splice variant 7 (AR-V7), which is constitutively activated and lacks the ligand-binding domain (LBD) while maintaining the nuclear localization signal and DNA-binding domain (DBD). This conformational change, even in the absence of the ligand, allows its retention within the nucleus, where it acts as a transcription factor repressing crucial tumor suppressor genes. AR-V7 is an important oncogenic driver and plays a role as an early diagnostic and prognostic marker, as well as a therapeutic target for antagonists such as niclosamide and TAS3681. Anti-AR-V7 drugs have shown promise in recent clinical investigations on this subset of patients. This mini-review focuses on the relevance of AR-V7 in the clinical manifestations of castration-resistant prostate cancer (CRPC) and summarizes redemptive therapeutic strategies.

CDK9: A Comprehensive Review of Its Biology, and Its Role as a Potential Target for Anti-Cancer Agents

Cyclin-dependent kinases (CDKs) are proteins pivotal to a wide range of cellular functions, most importantly cell division and transcription, and their dysregulations have been implicated as prominent drivers of tumorigenesis. Besides the well-established role of cell cycle CDKs in cancer, the involvement of transcriptional CDKs has been confirmed more recently. Most cancers overtly employ CDKs that serve as key regulators of transcription (e.g., CDK9) for a continuous production of short-lived gene products that maintain their survival. As such, dysregulation of the CDK9 pathway has been observed in various hematological and solid malignancies, making it a valuable anticancer target. This therapeutic potential has been utilized for the discovery of CDK9 inhibitors, some of which have entered human clinical trials. This review provides a comprehensive discussion on the structure and biology of CDK9, its role in solid and hematological cancers, and an updated review of the available inhibitors currently being investigated in preclinical and clinical settings.

α-Trifluoromethyl Chalcones as Potent Anticancer Agents for Androgen Receptor-Independent Prostate Cancer

α-Trifluoromethyl chalcones were prepared and evaluated for their antiproliferative activities against androgen-independent prostate cancer cell lines as well as five additional types of human tumor cell lines. The most potent chalcone 5 showed superior antitumor activity in vivo with both oral and intraperitoneal administration at 3 mg/kg. Cell-based mechanism of action studies demonstrated that 5 induced cell accumulation at sub-G1 and G2/M phases without interfering with microtubule polymerization. Furthermore, several cancer cell growth-related proteins were identified by using chalcone 5 as a bait for the affinity purification of binding proteins.

Synthesis and evaluation of tumor-homing peptides for targeting prostate cancer

High toxicity caused by chemotherapeutic drugs and the acquisition of drug resistance by cancer cells are the major drawbacks in cancer therapy. A promising approach to overcome the posed barriers is conjugating tumor-homing peptides to drugs or nanocarriers. Such high-affinity peptides can specifically target surface markers overexpressed by cancer cells, ensuring a rapid and cancer-specific uptake of the drugs. Since prostate-specific membrane antigen (PSMA) is overexpressed by aggressive prostate cancer cells, targeting this surface protein with peptide conjugates can lead to the development of effective strategies against prostate cancer. In this study, we aimed to determine which PSMA-binding peptide among peptides 563, 562 and 9-mer, show the highest selectivity towards PSMA using 22Rv1 prostate cancer cells, a cell line with moderate PSMA levels. Tumor-homing peptides were synthesized by fluorenylmethoxycarbonyl-based solid-phase peptide synthesis (Fmoc-SPPS) strategy, and evaluated for their prostate cancer cell-specific targeting efficiencies by flow cytometry. Our results showed that the PSMA-binding capacity of peptide 563 was superior to those of 562, 9-mer, and 5-mer; therefore, can be utilized as a potent-targeting agent not only in the treatment of high PSMA positive but also moderate PSMA positive prostate cancer tumors.

Undesirable Status of Prostate Cancer Cells after Intensive Inhibition of AR Signaling: Post-AR Era of CRPC Treatment

Recent advances in prostate cancer (PC) research unveiled real androgen receptor (AR) functions in castration-resistant PC (CRPC). Moreover, AR still accelerates PC cell proliferation via the activation of several mechanisms (e.g., mutation, variants, and amplifications in CRPC). New-generation AR signaling-targeted agents, inhibiting extremely the activity of AR, were developed based on these incontrovertible mechanisms of AR-induced CRPC progression. However, long-term administration of AR signaling-targeted agents subsequently induces the major problem that AR (complete)-independent CRPC cells present neither AR nor prostate-specific antigen, including neuroendocrine differentiation as a subtype of AR-independent CRPC. Moreover, there are few treatments effective for AR-independent CRPC with solid evidence. This study focuses on the transformation mechanisms of AR-independent from AR-dependent CRPC cells and potential treatment strategy for AR-independent CRPC and discusses them based on a review of basic and clinical literature.

Regular Voluntary Running Inhibits Androgen-Independent Prostate Cancer Growth in Mice

INTRODUCTION

Benefits of regular physical exercise were demonstrated as preventive and coadjuvant nonpharmacological anticancer therapy. However, the role of exercise in modulating prostate cancer behavior has yet to be established.

METHODS

Prostate tumors were induced in C57BL/6 male mice (n = 28) by subcutaneous inoculation of a suspension of murine androgen-independent RM1 cells (1.5 × 105 cells/500 μL phosphate-buffered saline) in the dorsal region. Mice were randomly allocated into 2 study groups: sedentary tumor-induced (n = 14) and exercised tumor-induced (n = 14). Exercise consisted of voluntary running in wheeled cages. Mice (n = 7 per group) were sacrificed either 14 or 28 days after cell inoculation to evaluate tumor weight and percentage of area occupied by immunohistochemistry stained cells for Ki-67 and TdT-mediated dUTP-biotin nick end labeling, used as surrogate markers of cell proliferation and apoptosis, respectively.

RESULTS

Compared with sedentary tumor-induced mice, the tumors developed by exercised tumor-induced mice were significantly smaller at 14 days (0.17 [0.12] g vs 0.48 [0.24] g, P < .05) and at 28 days (0.92 [0.73] g vs 2.09 [1.31] g, P < .05), with smaller Ki-67 and greater TdT-mediated dUTP-biotin nick end-labeling stained areas (P < .05).

CONCLUSION

These results suggest that regular voluntary running inhibits prostate cancer cell growth by reducing cell proliferation and enhancing apoptosis.

PPAR-gamma induced AKT3 expression increases levels of mitochondrial biogenesis driving prostate cancer

Peroxisome Proliferator-Activated Receptor Gamma (PPARG) is one of the three members of the PPAR family of transcription factors. Besides its roles in adipocyte differentiation and lipid metabolism, we recently demonstrated an association between PPARG and metastasis in prostate cancer. In this study a functional effect of PPARG on AKT serine/threonine kinase 3 (AKT3), which ultimately results in a more aggressive disease phenotype was identified. AKT3 has previously been shown to regulate PPARG co-activator 1 alpha (PGC1α) localisation and function through its action on chromosome maintenance region 1 (CRM1). AKT3 promotes PGC1α localisation to the nucleus through its inhibitory effects on CRM1, a known nuclear export protein. Collectively our results demonstrate how PPARG over-expression drives an increase in AKT3 levels, which in turn has the downstream effect of increasing PGC1α localisation within the nucleus, driving mitochondrial biogenesis. Furthermore, this increase in mitochondrial mass provides higher energetic output in the form of elevated ATP levels which may fuel the progression of the tumour cell through epithelial to mesenchymal transition (EMT) and ultimately metastasis.

Androgen Receptor-Related Non-coding RNAs in Prostate Cancer

Prostate cancer (PCa) is the second leading cause of cancer-related death among men in the United States. Androgen receptor (AR) signaling is the dominant oncogenic pathway in PCa and the main strategy of PCa treatment is to control the AR activity. A large number of patients acquire resistance to Androgen deprivation therapy (ADT) due to AR aberrant activation, resulting in castration-resistant prostate cancer (CRPC). Understanding the molecular mechanisms underlying AR signaling in the PCa is critical to identify new therapeutic targets for PCa patients. The recent advances in high-throughput RNA sequencing (RNA-seq) techniques identified an increasing number of non-coding RNAs (ncRNAs) that play critical roles through various mechanisms in different diseases. Some ncRNAs have shown great potentials as biomarkers and therapeutic targets. Many ncRNAs have been investigated to regulate PCa through direct association with AR. In this review, we aim to comprehensively summarize recent findings of the functional roles and molecular mechanisms of AR-related ncRNAs as AR regulators or targets in the progression of PCa.

Novel Strategies for Treating Castration-Resistant Prostate Cancer

The development of castration resistance is an inevitable pathway for the vast majority of patients with advanced prostate cancer. Recently, there have been significant breakthroughs in the understanding and management options of castration-resistant prostate cancer. Three novel hormonal agents showed survival benefits in non-metastatic patients. As for metastatic disease, there was an even wider range of management options being investigated. This review summarized advances in the management of castration-resistant prostate cancer (CRPC) including emerging data on novel imaging techniques and treatment strategies.

Structure-Activity Relationships for the Marine Natural Product Sintokamides: Androgen Receptor N-Terminus Antagonists of Interest for Treatment of Metastatic Castration-Resistant Prostate Cancer

Synthetic analogues of the marine natural product sintokamides have been prepared in order to investigate the structure-activity relationships for the androgen receptor N-terminal domain (AR NTD) antagonist activity of the sintokamide scaffold. An in vitro LNCaP cell-based transcriptional activity assay with an androgen-driven luciferase (Luc) reporter was used to monitor the potency of analogues. The data have shown that the chlorine atoms on the leucine side chains are essential for potent activity. Analogues missing the nonchlorinated methyl groups of the leucine side chains (C-1 and C-17) are just as active and in some cases more active than the natural products. Analogues with the natural R configuration at C-10 and the unnatural R configuration at C-4 are most potent. Replacing the natural propionamide N-terminus cap with the more sterically hindered pivaloylamide N-terminus cap leads to enhanced potency. The tetramic acid fragment and the methyl ether on the tetramic acid fragment are essential for activity. The SAR optimized analogue 76 is more selective, easier to synthesize, more potent, and presumed to be more resistant to proteolysis than the natural sintokamides.

Isorhamnetin inhibited the proliferation and metastasis of androgen-independent prostate cancer cells by targeting the mitochondrion-dependent intrinsic apoptotic and PI3K/Akt/mTOR pathway

The present study investigated the effects of Isorhamnetin on two types of prostate cancer cells (androgen-independent and androgen-dependent) and explored its possible mechanisms underlying such effects. Treatment with Isorhamnetin significantly inhibited cell growth and induced lactate dehydrogenase (LDH) release of androgen-independent DU145 and PC3 prostate cancer cells, but exhibited almost no toxicity effect on androgen-dependent LNCaP prostate cancer cell line or normal human prostate epithelial PrEC cells, which was achieved by the induction of apoptosis in a mitochondrion-dependent intrinsic apoptotic pathway. Furthermore, Isorhamnetin inhibited cell migration and invasion in concentration-dependent manners by enhancing mesenchymal−epithelial transition (MET) and inhibiting matrix metalloproteinase (MMP) 2 (MMP-2) and MMP-9 overexpression. In addition, Isorhamnetin also down-regulated the expression of phosphorylated PI3K (p-P13K), Akt (p-Akt), and mTOR (p-mTOR) proteins in both cancer cells, revealing Isorhamnetin to be a selective PI3K–Akt–mTOR pathway inhibitor. In summary, these findings propose that Isorhamnetin might be a novel therapeutic candidate for the treatment of androgen-independent prostate cancer.

Anti-tumor activities of Panax quinquefolius saponins and potential biomarkers in prostate cancer

BACKGROUND

Prostate carcinoma is the second most common cancer among men worldwide. Developing new therapeutic approaches and diagnostic biomarkers for prostate cancer (PC) is a significant need. The Chinese herbal medicine Panax quinquefolius saponins (PQS) have been reported to show anti-tumor effects. We hypothesized that PQS exhibits anti-cancer activity in human PC cells and we aimed to search for novel biomarkers allowing early diagnosis of PC.

METHODS

We used the human PC cell line DU145 and the prostate epithelial cell line PNT2 to perform cell viability assays, flow cytometric analysis of the cell cycle, and FACS-based apoptosis assays. Microarray-based gene expression analysis was used to display specific gene expression patterns and to search for novel biomarkers. Western blot and quantitative real-time PCR were performed to demonstrate the expression levels of multiple cancer-related genes.

RESULTS

Our data showed that PQS inhibited the viability of DU145 cells and induced cell cycle arrest at the G1 phase. A significant decrease in DU145 cell invasion and migration were observed after 24 h treatment by PQS. PQS up-regulated the expression levels of p21, p53, TMEM79, ACOXL, ETV5, and SPINT1 while it down-regulated the expression levels of bcl2, STAT3, FANCD2, DRD2, and TMPRSS2.

CONCLUSION

PQS promoted cells apoptosis and inhibited the proliferation of DU145 cells, which suggests that PQS may be effective for treating PC. TMEM79 and ACOXL were expressed significantly higher in PNT2 than in DU145 cells and could be novel biomarker candidates for PC diagnosis.

Bicyclic Chalcones as Mitotic Inhibitors for Overcoming Androgen Receptor-Independent and Multidrug-Resistant Prostate Cancer

To improve the biological effects of the lead compound 5'-chloro-2,2'-dihydroxychalcone (Cl-DHC), bicyclic aromatic chalcones were designed, synthesized, and evaluated against androgen-independent prostate cancer (PCa) DU145 and PC-3 cell proliferation. Newly synthesized bi-naphthyl derivatives 2 and 3 suppressed the proliferation of these two cell lines and also taxane-resistant prostate cancer cell lines at a submicromolar level. The two compounds were 4-18 times more potent than the parent molecule Cl-DHC. A structure-activity relationship analysis revealed that the orientation of the 10π-electron ring-A naphthalene had a significant effect on the activity. Mode-of-action studies in KB-VIN cells demonstrated that 2 and 3 arrested cells in mitosis at prometaphase and metaphase followed by induction of sub-G1 accumulation. Thus, 2 and 3 have good potential as leads for continued development of treatments for cancers especially for not only androgen-independent PCa but also multidrug-resistant tumors.

Role of Testosterone Levels on the Combinatorial Effect of Boswellia serrata Extract and Enzalutamide on Androgen Dependent LNCaP Cells and in Patient Derived Cells

Co-therapy with herbal extracts along with current clinical drugs is being increasingly recognized as a useful complementary treatment for cancer. The anti-cancer property of the phyto-derivative acetyl-11 keto β boswellic acid (AKBA) has been studied in many cancers, including prostate cancer. However, the whole extract of the gum resin Boswellia serrata (BS) and anti-androgen enzalutamide has not been explored in prostate cancer to date. We hypothesized that the BS extract containing 30% (AKBA) with enzalutamide acted synergistically in the early phase of cancer, especially in LNCaP cells, by inhibiting androgen receptor (AR) and by reducing cell proliferation, and further, that the extract would be superior to the action of the active ingredient AKBA when used alone or in combination with enzalutamide. To test our hypothesis, we treated LNCaP cells with BS extract or AKBA and enzalutamide both individually and in combination to analyze cell viability under different levels of dihydrotestosterone (DHT). The inhibition of androgen receptor (AR) followed by the expression of prostate-specific antigen (PSA) and the efflux mechanism of the cells were analyzed to determine the effect of the combination on the cellular mechanism. Cells derived from prostate cancer patients were also tested with the combination. Only 6 µM enzalutamide along with BS in the range of 4.1 µg/ml to 16.4 µg/ml gave the best synergistic results with nearly 50% cell killing even though standard enzalutamide doses were as high as 48 µM. Cell killing was most effective at intermediate DHT concentrations of approximately 1 nM, which corresponds to normal physiological serum levels of DHT. The Pgp expression level and the androgen receptor expression levels were reduced under the combination treatment; the former helping to minimize drug efflux and the latter by reducing the sensitivity to hormonal changes. Furthermore, the combination reduced the PSA level secreted by the cells. In contrast, AKBA could not achieve the needed synergism for adequate cell killing at equivalent concentrations. The combination of enzalutamide and BS extract containing 30% AKBA because of their synergistic interaction is an attractive therapeutic option for treating early stage (hormone-dependent) prostate cancer and is superior to the use of AKBA alone.

Diagnostic Strategies for Treatment Selection in Advanced Prostate Cancer

Prostate Cancer (PCa) is a leading cause of morbidity and mortality among men worldwide. For most men with PCa, their disease will follow an indolent course. However, advanced PCa is associated with poor outcomes. There has been an advent of new therapeutic options with proven efficacy for advanced PCa in the last decade which has improved survival outcomes for men with this disease. Despite this, advanced PCa continues to be associated with a high rate of death. There is a lack of strong evidence guiding the timing and sequence of these novel treatment strategies. This paper focuses on a review of the strategies for diagnostic and the current evidence available for treatment selection in advanced PCa.

Distinct roles for the RNA-binding protein Staufen1 in prostate cancer

BACKGROUND

Prostate cancer is one of the most common malignant cancers with the second highest global rate of mortality in men. During the early stages of disease progression, tumour growth is local and androgen-dependent. Despite treatment, a large percentage of patients develop androgen-independent prostate cancer, which often results in metastases, a leading cause of mortality in these patients. Our previous work on the RNA-binding protein Staufen1 demonstrated its novel role in cancer biology, and in particular rhabdomyosarcoma tumorigenesis. To build upon this work, we have focused on the role of Staufen1 in other forms of cancer and describe here the novel and differential roles of Staufen1 in prostate cancer.

METHODS

Using a cell-based approach, three independent prostate cancer cell lines with different characteristics were used to evaluate the expression of Staufen1 in human prostate cancer relative to control prostate cells. The functional impact of Staufen1 on several key oncogenic features of prostate cancer cells including proliferation, apoptosis, migration and invasion were systematically investigated.

RESULTS

We show that Staufen1 levels are increased in all human prostate cancer cells examined in comparison to normal prostate epithelial cells. Furthermore, Staufen1 differentially regulates growth, migration, and invasion in the various prostate cancer cells assessed. In LNCaP prostate cancer cells, Staufen1 regulates cell proliferation through mTOR activation. Conversely, Staufen1 regulates migration and invasion of the highly invasive, bone metastatic-derived, PC3 prostate cells via the activation of focal adhesion kinase.

CONCLUSIONS

Collectively, these results show that Staufen1 has a direct impact in prostate cancer development and further demonstrate that its functions vary amongst the prostate cancer cell types. Accordingly, Staufen1 represents a novel target for the development of much-needed therapeutic strategies for prostate cancer.

A population K-PD model analysis of long-term testosterone inhibition in prostate cancer patients undergoing intermittent androgen deprivation therapy

Intermittent androgen deprivation therapy with gonadotropin-releasing-hormone (GnRH) agonists can prevent or delay disease progression and development of castration resistant prostate cancer for subpopulations of prostate cancer patients. It may also reduce risk and severity of side effects associated with chemical castration in prostate cancer (PCa) patients. One of the earliest comprehensively documented clinical trials on this was reported in a Canadian patient population treated with leuprorelin preceded by a lead-in with cyproterone acetate. A systems-based mixed effect analysis of testosterone response in active and recovery phases allows inference of new information from this patient population. Efficacy of androgen deprivation therapy is presumed to depend on a treshold value for testosterone at the nadir, below which no additional beneficial effects on PSA reponse can be expected, and occurance of testosterone breakthroughs during active therapy. The present analysis results in a mixed effect model, incorporating GnRH receptor activation, testosterone turnover and feedback mechanisms, describing and predicting testosterone inhibition under intermittent androgen deprivation therapy on the individual and population level, during multiple years of therapy. Testosterone levels in these patients decline over time with an estimated first order rate constant of 0.083 year^-1(T_1/2 = 8.4 y), with a substantial distribution among this patient population, compared to the general population. PCa patients leaving the trial due to unmanageble PSA relapse appear to have slightly higher testosterone levels at the nadir than sustained responders. These findings are expected to contribute to an increased understanding of the role of testosterone in long term disease progression of prostate cancer.

Phasing the intranuclear organization of steroid hormone receptors

Steroid receptors (SRs) encompass a family of transcription factors that regulate the expression of thousands of genes upon binding to steroid hormones and include the glucocorticoid, androgen, progesterone, estrogen and mineralocorticoid receptors. SRs control key physiological and pathological processes, thus becoming relevant drug targets. As with many other nuclear proteins, hormone-activated SRs concentrate in multiple discrete foci within the cell nucleus. Even though these foci were first observed ∼25 years ago, their exact structure and function remained elusive. In the last years, new imaging methodologies and theoretical frameworks improved our understanding of the intranuclear organization. These studies led to a new paradigm stating that many membraneless nuclear compartments, including transcription-related foci, form through a liquid–liquid phase separation process. These exciting ideas impacted the SR field by raising the hypothesis of SR foci as liquid condensates involved in transcriptional regulation. In this work, we review the current knowledge about SR foci formation under the light of the condensate model, analyzing how these structures may impact SR function. These new ideas, combined with state-of-the-art techniques, may shed light on the biophysical mechanisms governing the formation of SR foci and the biological function of these structures in normal physiology and disease.

Targeting androgen receptor signaling with MicroRNAs and Curcumin: a promising therapeutic approach for Prostate Cancer Prevention and intervention

Prostate cancer (PC) is a multifactorial disease characterized by the abrogation of androgen receptor signaling. Advancement in microbiology techniques has highlighted the significant role of microRNAs (miRNAs) in the progression of PC cells from an androgen-dependent to an androgen-independent state. At that stage, prostate tumors also fail to respond to currently practiced hormone therapies. So, studies in recent decades are focused on investigating the anti-tumor effects of natural compounds in PC. Curcumin is widely recognized and now of huge prestige for its anti-proliferative abilities in different types of cancer. However, its limited solubility, compatibility, and instability in the aqueous phase are major hurdles when administering. Nanoformulations have proven to be an excellent drug delivery system for various drugs and can be used as potential delivery platforms for curcumin in PC. In this review, a shed light is given on the miRNAs-mediated regulation of androgen receptor (AR) signaling and miRNA-curcumin interplay in PC, as well as on curcumin-based nanoformulations that can be used as possible therapeutic solutions for PC.

Puerarin induces apoptosis in prostate cancer cells via inactivation of the Keap1/Nrf2/ARE signaling pathway

In this study, we examined the antitumor effects of Puerarin (PEU) on androgen-independent (DU145 and PC-3) and androgen-dependent (LNCaP) prostate cancer cells, and explored its potential mechanisms. Supplement with PEU (2.5 μM, 5 μM, and 10 μM) exhibited a marked inhibitory effect against the growth of DU145 and PC-3 cells, especially beyond 24 h, whereas there is only slight growth inhibitory effect on LNCaP cells at the high concentration of 10 μM at 72 h. This loss of cell viability in DU145 and PC-3 cells by PEU was mediated by the induction of apoptosis via up-regulation of Bax and cleaved-caspase-3, but downregulation of Bcl-2. Moreover, more intracellular ROS and LDH production were observed in DU145 and PC-3 cells upon PEU treatment. Meanwhile, the amount of pro-inflammatory cytokines (IL-1β and IL-6) was increased, but the content of anti-inflammatory cytokines IL-10 was attenuated. Additionally, PEU pretreatment resulted in an increase of Keap1 protein expression, and a decline of Nrf2, HO-1 and NQO1 protein expression in DU145 and PC3 cells. The present findings indicated that PEU exerted its antitumor activities toward androgen-independent prostate cancer cells via inactivation of Keap1/NrF2/ARE signaling pathway.

Resistance to Antiandrogens in Prostate Cancer: Is It Inevitable, Intrinsic or Induced?

Increasingly sophisticated therapies for chemical castration dominate first-line treatments for locally advanced prostate cancer. However, androgen deprivation therapy (ADT) offers little prospect of a cure, as resistant tumors emerge rather rapidly, normally within 30 months. Cells have multiple mechanisms of resistance to even the most sophisticated drug regimes, and both tumor cell heterogeneity in prostate cancer and the multiple salvage pathways result in castration-resistant disease related genetically to the original hormone-naive cancer. The timing and mechanisms of cell death after ADT for prostate cancer are not well understood, and off-target effects after long-term ADT due to functional extra-prostatic expression of the androgen receptor protein are now increasingly being recorded. Our knowledge of how these widely used treatments fail at a biological level in patients is deficient. In this review, I will discuss whether there are pre-existing drug-resistant cells in a tumor mass, or whether resistance is induced/selected by the ADT. Equally, what is the cell of origin of this resistance, and does it differ from the treatment-naïve tumor cells by differentiation or dedifferentiation? Conflicting evidence also emerges from studies in the range of biological systems and species employed to answer this key question. It is only by improving our understanding of this aspect of treatment and not simply devising another new means of androgen inhibition that we can improve patient outcomes.

Male castration increases adiposity via small intestinal microbial alterations

Castration of young males is widely used in the cattle industry to improve meat quality, but the mechanism linking hypogonadism and host metabolism is not clear. Here, we use metataxonomic and metabolomic approaches to evaluate the intestinal microbiota and host metabolism in male, castrated male (CtM), and female cattle. After pubescence, the CtM cattle harbor distinct ileal microbiota dominated by the family Peptostreptococcaceae and exhibit distinct serum and muscle amino acid profiles (i.e., highly abundant branched-chain amino acids), with increased extra- and intramuscular fat storage. We also evaluate the causative factor(s) that underpin the alteration of the intestinal microbiota and host metabolic phenotype in response to hypogonadism. Castration of male mice phenocopies both the intestinal microbial alterations and obese-prone metabolism observed in cattle. Antibiotic treatment and fecal microbiota transplantation experiments in a mouse model confirm that the intestinal microbial alterations associated with hypogonadism are a key contributor to the obese phenotype in the CtM animals. Collectively, targeting the gut microbiota is a potential therapeutic strategy for the treatment of both hypogonadism and obesity.

Modeling the synergistic properties of drugs in hormonal treatment for prostate cancer

Prostate cancer is one of the most prevalent cancers in men, with increasing incidence worldwide. This public health concern has inspired considerable effort to study various aspects of prostate cancer treatment using dynamical models, especially in clinical settings. The standard of care for metastatic prostate cancer is hormonal therapy, which reduces the production of androgen that fuels the growth of prostate tumor cells prior to treatment resistance. Existing population models often use patients' prostate-specific antigen levels as a biomarker for model validation and for finding optimal treatment schedules; however, the synergistic effects of drugs used in hormonal therapy have not been well-examined. This paper describes the first mathematical model that explicitly incorporates the synergistic effects of two drugs used to inhibit androgen production in hormonal therapy. The drugs are cyproterone acetate, representing the drug family of anti-androgens that affect luteinizing hormones, and leuprolide acetate, representing the drug family of gonadotropin-releasing hormone analogs. By fitting the model to clinical data, we show that the proposed model can capture the dynamics of serum androgen levels during intermittent hormonal therapy better than previously published models. Our results highlight the importance of considering the synergistic effects of drugs in cancer treatment, thus suggesting that the dynamics of the drugs should be taken into account in optimal treatment studies, particularly for adaptive therapy. Otherwise, an unrealistic treatment schedule may be prescribed and render the treatment less effective. Furthermore, the drug dynamics allow our model to explain the delay in the relapse of androgen the moment a patient is taken off treatment, which supports that this delay is due to the residual effects of the drugs.

A Novel White-to-Blue Colony Formation Assay to Select for Optimized sgRNAs

CRISPR/Cas9-mediated genome editing technology consists of a single-guide RNA (sgRNA), and the Cas9 endonuclease has the potential to treat genetic diseases in most tissues and organisms. In this system, the Cas9 protein can be directed to target genomic DNA sequences as "molecular scissors" with the guidance of sgRNAs. However, the target-specific activities of different sgRNAs are highly variable; thus, it is crucial to search for a simple, quick and economical method to screen for optimized sgRNAs with high target specificity. We have adopted and verified a newly developed white-to-blue colony formation assay to quickly screen for sgRNAs optimized for the EphA2 gene, which is highly expressed in hormone-resistant prostate cancer (PC-3) cells. This assay promises to screen for optimized sgRNAs more simply, rapidly, and efficiently. Our results suggest that the white-to-blue colony formation assay might be a useful screening strategy to quickly select for optimized sgRNAs.

Identification of AR-V7 downstream genes commonly targeted by AR/AR-V7 and specifically targeted by AR-V7 in castration resistant prostate cancer

Primary prostate cancer (PC) progresses to castration-resistant PC (CRPC) under androgen deprivation therapy, by mechanisms e.g. expression of androgen receptor (AR) splice variant-7 (AR-V7). Here we conducted comprehensive epigenome and transcriptome analyses comparing LNCaP, primary PC cells, and LNCaP95, AR-V7-expressing CRPC cells derived from LNCaP. Of 399 AR-V7 target regions identified through ChIP-seq analysis, 377 could be commonly targeted by hormone-stimulated AR, and 22 were specifically targeted by AR-V7. Among genes neighboring to these AR-V7 target regions, 78 genes were highly expressed in LNCaP95, while AR-V7 knockdown led to significant repression of these genes and suppression of growth of LNCaP95. Of the 78 AR-V7 target genes, 74 were common AR/AR-V7 target genes and 4 were specific AR-V7 target genes; their most suppressed genes by AR-V7 knockdown were NUP210 and SLC3A2, respectively, and underwent subsequent analyses. NUP210 and SLC3A2 were significantly upregulated in clinical CRPC tissues, and their knockdown resulted in significant suppression of cellular growth of LNCaP95 through apoptosis and growth arrest. Collectively, AR-V7 contributes to CRPC proliferation by activating both common AR/AR-V7 target and specific AR-V7 target, e.g. NUP210 and SLC3A2.

α-Actinin-4 Promotes the Progression of Prostate Cancer Through the Akt/GSK-3β/β-Catenin Signaling Pathway

The first-line treatment for prostate cancer (PCa) is androgen ablation therapy. However, prostate tumors generally recur and progress to androgen-independent PCa (AIPC) within 2–3 years. α-Actinin-4 (ACTN4) is an actin-binding protein that belongs to the spectrin gene superfamily and acts as an oncogene in various cancer types. Although ACTN4 is involved in tumorigenesis and the epithelial–mesenchymal transition of cervical cancer, the role of ACTN4 in PCa remains unknown. We found that the ACTN4 expression level increased during the transition from androgen-dependent PCa to AIPC. ACTN4 overexpression resulted in enhanced proliferation and motility of PCa cells. Increased β-catenin due to ACTN4 promoted the transcription of genes involved in proliferation and metastasis such as CCND1 and ZEB1. ACTN4-overexpressing androgen-sensitive PCa cells were able to grow in charcoal-stripped media. In contrast, ACTN4 knockdown using si-ACTN4 and ACTN4 nanobody suppressed the proliferation, migration, and invasion of AIPC cells. Results of the xenograft experiment revealed that the mice injected with LNCaP^ACTN4 cells exhibited an increase in tumor mass compared with those injected with LNCaP^Mock cells. These results indicate that ACTN4 is involved in AIPC transition and promotes the progression of PCa.

Covid-19 pathogenesis in prostatic cancer and TMPRSS2-ERG regulatory genetic pathway

Members of Coronaviridae family have been the source of respiratory illnesses. The outbreak of SARS-CoV-2 that produced a severe lung disease in afflicted patients in China and other countries was the reason for the incredible attention paid toward this viral infection. It is known that SARS-CoV-2 is dependent on TMPRSS2 activity for entrance and subsequent infection of the host cells and TMPRSS2 is a host cell molecule that is important for the spread of viruses such as coronaviruses.

Different factors can increase the risk of prostate cancer, including older age, a family history of the disease. Androgen receptor (AR) initiates a transcriptional cascade which plays a serious role in both normal and malignant prostate tissues. TMPRSS2 protein is highly expressed in prostate secretory epithelial cells, and its expression is dependent on androgen signals. One of the molecular signs of prostate cancer is TMPRSS2-ERG gene fusion. In TMPRSS2-ERG-positive prostate cancers different patterns of changed gene expression can be detected. The possible molecular relation between fusion positive prostate cancer patients and the increased risk of lethal respiratory viral infections especially SARS-CoV-2 can candidate TMPRSS2 as an attractive drug target. The studies show that some molecules such as nicotinamide, PARP1, ETS and IL-1R can be studied deeper in order to control SARS-CoV-2 infection especially in prostate cancer patients.

This review attempts to investigate the possible relation between the gene expression pattern that is produced through TMPRSS2-ERG fusion positive prostate cancer and the possible influence of these fluctuations on the pathogenesis and development of viral infections such as SARS-CoV-2.

Effects of MTX-23, a Novel PROTAC of Androgen Receptor Splice Variant-7 and Androgen Receptor, on CRPC Resistant to Second-Line Antiandrogen Therapy

Although second-line antiandrogen therapy (SAT) is the standard of care in men with castration-resistant prostate cancer (CRPC), resistance inevitably occurs. One major proposed mechanism of resistance to SAT involves the emergence of androgen receptor (AR) splice variant-7, AR-V7. Recently, we developed MTX-23 using the principle of proteolysis targeting chimera (PROTAC) to target both AR-V7 and AR-full length (AR-FL). MTX-23 has been designed to simultaneously bind AR's DNA binding domain (DBD) and the Von Hippel-Lindau (VHL) E3 ubiquitin ligase. Immunoblots demonstrated that MTX-23's degradation concentration 50% (DC₅₀) for AR-V7 and AR-FL was 0.37 and 2 μmol/L, respectively. Further studies revealed that MTX-23 inhibited prostate cancer cellular proliferation and increased apoptosis only in androgen-responsive prostate cancer cells. The antiproliferative effect of MTX-23 was partially reversed when either AR-V7 or AR-FL was overexpressed and was completely abrogated when both were overexpressed. To assess the potential therapeutic value of MTX-23, we next generated 12 human prostate cancer cell lines that are resistant to the four FDA-approved SAT agents-abiraterone, enzalutamide, apalutamide, and darolutamide. When resistant cells were treated with MTX-23, decreased cellular proliferation and reduced tumor growth were observed both in vitro and in mice. These results collectively suggest that MTX-23 is a novel PROTAC small molecule that may be effective against SAT-resistant CRPC by degrading both AR-V7 and AR-FL.

When the chains do not break: the role of USP10 in physiology and pathology

Deubiquitination is now understood to be as important as its partner ubiquitination for the maintenance of protein half-life, activity, and localization under both normal and pathological conditions. The enzymes that remove ubiquitin from target proteins are called deubiquitinases (DUBs) and they regulate a plethora of cellular processes. DUBs are essential enzymes that maintain intracellular protein homeostasis by recycling ubiquitin. Ubiquitination is a post-translational modification where ubiquitin molecules are added to proteins thus influencing activation, localization, and complex formation. Ubiquitin also acts as a tag for protein degradation, especially by proteasomal or lysosomal degradation systems. With ~100 members, DUBs are a large enzyme family; the ubiquitin-specific peptidases (USPs) being the largest group. USP10, an important member of this family, has enormous significance in diverse cellular processes and many human diseases. In this review, we discuss recent studies that define the roles of USP10 in maintaining cellular function, its involvement in human pathologies, and the molecular mechanisms underlying its association with cancer and neurodegenerative diseases. We also discuss efforts to modulate USPs as therapy in these diseases.

[The impact of the androgen receptor splice variant AR-V7 on the prognosis and treatment of advanced prostate cancer]

A recently discovered mechanism enabling prostate cancer cells to escape the effects of endocrine therapies consists in the synthesis of C-terminally truncated, constitutively active androgen receptor (AR) splice variants (AR-V). Devoid of a functional C-terminal hormone/ligand binding domain, various AR-Vs are insensitive to therapies targeting the androgen/AR signalling axis. Preliminary studies suggest that AR-V7, the most common AR-V, is a promising predictive tumour marker and a relevant selection marker for the treatment of advanced prostate cancer. This review critically outlines recent advances in AR-V7 diagnostics and presents an overview of current AR-V7 targeted therapies.

Endobolome, a New Concept for Determining the Influence of Microbiota Disrupting Chemicals (MDC) in Relation to Specific Endocrine Pathogenesis

Endogenous steroid hormones and Endocrine Disrupting Chemicals (EDC) interact with gut microbiota through different pathways. We suggest the use of the term "endobolome" when referring to the group of gut microbiota genes and pathways involved in the metabolism of steroid hormones and EDC. States of dysbiosis and reduced diversity of the gut microbiota may impact and modify the endobolome resulting at long-term in the development of certain pathophysiological conditions. The endobolome might play a central role in the gut microbiota as seen by the amount of potentially endobolome-mediated diseases and thereby it can be considered an useful diagnostic tool and therapeutic target for future functional research strategies that envisage the use of next generation of probiotics. In addition, we propose that EDC and other xenobiotics that alter the gut microbial composition and its metabolic capacities should be categorized into a subgroup termed "microbiota disrupting chemicals" (MDC). This will help to distinguish the role of contaminants from other microbiota natural modifiers such as those contained or released from diet, environment, physical activity and stress. These MDC might have the ability to promote specific changes in the microbiota that can ultimately result in common intestinal and chronic or long-term systemic diseases in the host. The risk of developing certain disorders associated with gut microbiota changes should be established by determining both the effects of the MDC on gut microbiota and the impact of microbiota changes on chemicals metabolism and host susceptibility. In any case, further animal controlled experiments, clinical trials and large epidemiological studies are required in order to establish the concatenated impact of the MDC-microbiota-host health axis.

Curcumin against Prostate Cancer: Current Evidence

Cancer is a condition characterized by remarkably enhanced rates of cell proliferation paired with evasion of cell death. These deregulated cellular processes take place following genetic mutations leading to the activation of oncogenes, the loss of tumor suppressor genes, and the disruption of key signaling pathways that control and promote homeostasis. Plant extracts and plant-derived compounds have historically been utilized as medicinal remedies in different cultures due to their anti-inflammatory, antioxidant, and antimicrobial properties. Many chemotherapeutic agents used in the treatment of cancer are derived from plants, and the scientific interest in discovering plant-derived chemicals with anticancer potential continues today. Curcumin, a turmeric-derived polyphenol, has been reported to possess antiproliferative and proapoptotic properties. In the present review, we summarize all the in vitro and in vivo studies examining the effects of curcumin in prostate cancer.

The clinical benefit of sequential therapy with androgen receptor axis-targeted agents alone in patients with castration-resistant prostate cancer: A propensity score-matched comparison study

BACKGROUND

The optimal sequential therapy for castration-resistant prostate cancer (CRPC) remains unknown. In recent years, some doubts have emerged regarding the clinical benefit of sequential therapy with androgen receptor axis-targeted agents (ART) such as abiraterone (ABI) or enzalutamide (ENZ) for patients with CRPC. We compared the effect of ART-to-ART (AA) sequential therapy after castration resistance with that of docetaxel (DTX)-combined sequential therapy (ART to DTX or DTX to ART) in patients with CRPC.

METHODS

We retrospectively identified and analyzed the data of 315 patients with CRPC treated in our seven affiliated institutions between 2009 and 2019. All patients received either DTX or ART (ABI or ENZ) as the first- or second-line therapy after castration resistance. We compared the overall survival (OS) and the second progression-free survival (PFS2), calculated from the initiation of first-line therapy after castration resistance, between the AA sequence group and the DTX-combined sequence group. PFS2 was defined as the period from the start of first-line treatment after castration resistance to progression on second-line treatment. To minimize selection bias from possible confounders, we performed propensity score matching using one-to-one nearest neighbor matching without replacement.

RESULTS

Overall, 106 and 209 patients were administered the AA sequential therapy and DTX-combined sequential therapy, respectively. The clinicopathological variables of patients were well balanced after propensity score matching, and there were no significant differences between the two groups. In the propensity score-matched cohort, OS was not significantly different between the two groups (median, 37.9 vs. 45.4 months; hazard ratio [HR], 1.10; 95% confidence interval [CI], 0.68-1.79; p = .701), while PFS2 was significantly shorter in the AA group than in the DTX-combined group (median, 12.9 vs. 21.6 months; HR, 1.70; 95% CI, 1.16-2.48; p = .007).

CONCLUSIONS

Certain patients with CRPC can benefit from ART-to-ART sequential therapy in a daily clinical setting.

Paying the price for standing tall: Fluid mechanics of prostate pathology

BACKGROUND

Age-dependent increase in the incidence of benign prostatic hyperplasia (BPH) and prostate cancer (PCa) are both related to cell proliferation and survival controlled by intraprostatic free testosterone (FT) concentration. Paradoxically, BPH and PCa occur as circulating testosterone levels decrease, so any possible relationship between testosterone levels and development of BPH and PCa remains obscure.

RESULTS

In BPH the enlarging prostate is exposed to high testosterone levels arriving directly from the testes at concentrations about hundredfold higher than systemic FT. This occurs because venous blood from the testes is diverted into the prostate due to the elevated hydrostatic pressure of blood in the internal spermatic veins (ISVs). Elevated pressure is caused by the destruction of one-way valves (clinically detected as varicocele), a unique phenomenon related to human erect posture. While standing, human males are ISVs vertically oriented, resulting in high intraluminal hydrostatic pressures-a phenomenon not found in quadrupeds. In this communication, we demonstrate the fluid mechanics' phenomena at the basis of varicocele leading to prostate pathology.

CONCLUSIONS

So far, varicocele has been studied mostly for its etiologic role in male infertility and, thus, for its effects on the testes. It is becoming clear that varicocele is a major etiologic factor in BPH and likely also in PCa. Restoring normal testicular venous pressure by treatment of the abnormal ISV's in varicocele has been shown to avert the flow from the prostate with the effect of reducing prostate volume, alleviating symptoms of BPH, and increasing concentrations of circulating FT.