Bypass mechanisms of the androgen receptor pathway in therapy-resistant prostate cancer cell models

Clinical data investigation identifies MARK3 as an oncogenic driver in castration-resistant prostate cancer

Castration-resistant prostate cancer (CRPC) represents an aggressive and fatal form of prostate cancer that emerges following resistance to androgen deprivation therapy. Despite the availability of various drugs that can enhance the quality and prolong the survival of CRPC patients, resistance to these therapies is frequently observed, making the disease increasingly difficult to treat. Altered expression of kinases and phosphatases is a critical driver of CRPC and presents a potential target for more effective treatments. In this study, we have performed comprehensive transcriptomic analysis of ∼359 normal and CRPC patient samples from The Cancer Genome Atlas to identify the differentially expressed kinases and phosphatases in patient samples. We shortlisted the candidate genes based on their differential expression profiles, associations with patient survival, Gleason scores, and their impact on the fitness of prostate cancer cell lines. Our in-silico analysis identified microtubule affinity-regulating kinase 3 (MARK3) as a novel CRPC driver that is upregulated in CRPC patients, linked with poor survival outcomes, and affects the fitness of CRPC cells. Furthermore, we found that pharmacological inhibition of MARK3 using PCC0208017, a MARK3 inhibitor, leads to reduced cell viability, migration potential, and cell cycle arrest in the G1 phase in prostate cancer cells. Additionally, RNA sequencing analysis in 22Rv1 cells treated with the MARK3 inhibitor revealed that MARK3 influences genes involved in androgen response, epithelial-mesenchymal transition, mTOR, and myc-signalling, underscoring its pivotal role in CRPC progression. Taken together, our results establish MARK3 as a novel and promising therapeutic target in CRPC.

Characterization of new non-ATP dependent inhibitors of TLK1 as potential molecules for treating prostate cancer

Androgen deprivation therapy (ADT) is currently the primary treatment regime for Prostate cancer patients for advanced and local tumors. However, 70 % of the patients develop resistance to ADT due to various underlying mechanisms over the years. Researchers have identified the involvement of Tousled-like kinase 1 (TLK1) as a primary reason for ADT resistance and metastatic tumor development, representing TLK1 as an effective druggable target for prostate cancer. To date, phenothiazines-which are known antipsychotic drugs, are the only class of inhibitors reported against TLK1. In this study, we focus on developing a new class of TLK1 inhibitors to broaden the spectrum of understanding TLK1 inhibition. As an approach, we designed, synthesized, and validated pyridazinone-fused indole molecules with potent TLK1 inhibition with the concept of ligand-based drug discovery. The inhibition studies and biochemical assays identified a molecule 5n with better inhibition potential than reported J54. Also, the synthesized inhibitors are toxic to androgen-sensitive LNCaP prostate cancer cell lines in sub-micromolar levels and inhibit the TLK1 pathway in cells. Additionally, the combination of anti-androgens and 5n reduces the clonogenicity of cells, causes an accumulation of DNA damage, and induces apoptosis cell death in the LNCaP cells. We anticipate that our step towards exploring a new class of potent TLK1 inhibitors would aid in elevating the therapeutics to existing prostate cancer therapy and provide strong validation for future drug design for more potent and specific TLK1 inhibitors.

Interactions between androgen and IGF1 axes in prostate tumorigenesis

Androgen signalling through the androgen receptor (AR) is essential for prostate tumorigenesis. However, androgen signalling pathways also interact with other growth factor-mediated signalling pathways to regulate the prostatic cell cycle, differentiation, apoptosis and proliferation in the initiation and progression of prostate cancer. Insulin-like growth factor 1 (IGF1) is one of the most prominent growth factors in prostate tumorigenesis. Clinical and experimental evidence has demonstrated that IGF1 signalling supports both androgen-dependent and androgen-independent prostate tumorigenesis, suggesting that improved understanding of the interactions between the IGF1 and androgen axes might aid the development of new therapeutic strategies. Available data have shown a dynamic role of androgen-AR signalling in the activation of IGF1-signalling pathways by augmenting transcription of the IGF1 receptor in prostatic basal epithelial cells and by increasing IGF1 secretion through the suppression of IGF-binding protein 3 expression in prostatic stromal cells. In turn, IGF1 stimulates Wnt-β-catenin signalling in prostatic basal progenitors to promote prostatic oncogenic transformation and prostate cancer development. These findings highlight the cooperative, autocrine and paracrine interactions that underlie the oncogenic effects of androgens and IGF1 and open up new opportunities for therapeutic targeting.

Fatty acid binding protein 5 inhibitors as novel anticancer agents against metastatic castration-resistant prostate cancer

Prostate cancer (PCa) is one of the most common malignancies diagnosed among men and is the second leading cause of cancer-related death. Despite recent advancements in early diagnosis of PCa, androgen deprivation therapy (ADT) remains the most common treatment of PCa. Docetaxel (DTX) and Cabazitaxel (CTX) are two of the most extensively used drugs for metastatic castration-resistant prostate cancer (mCRPC). However, there is a clear medical need for newer and more efficacious therapies for CRPC. FABP5 is overexpressed in prostate cancer cells and chaperones fatty acids to PPARs, which leads to the upregulation of proangiogenic factors, resulting in cell survival and metastasis. The critical role and upregulation of FABP5 in PCa make FABP5 an excellent druggable target for CRPC. We reported a promising anti-PCa activity of truxillic acid monoester (TAME)-based FABP5 inhibitors (SB-FIs) and their synergy with DTX and CTX in vitro and in vivo against PC-3 cells and PC-3 tumor xenografts. In the present work, we performed an extensive SAR study on the potencies of 2nd- and 3rd-generation SB-FIs against PC-3 and RCaP cell lines. RCaP is a mouse PCa cell line, resistant to anti-androgen and first-line taxane chemotherapies, and shows a high level of the Fabp5-gene. This SAR study led to the identification of a number of 3rd-generation SB-FIs with strong cytotoxicity against these two PCa cell lines. Cell cycle analysis of selected SB-FIs revealed a clear evolution of apoptotic potency in the 1st-, 2nd- and 3rd-generation SB-FIs. Since taxanes, DTX and CTX, are ineffective against RCaP cell line, we selected a topoisomerase I inhibitor, topotecan (TPT) as a replacement for taxanes. We screened the library of SB-FIs for synergy with TPT and identified 3 SB-FIs (L3, α-11 and α-4), exhibiting strong synergy, which could remarkably expand the therapeutic window of TPT.

Inhibition of Galectin-1 and Androgen Receptor Axis Enhances Enzalutamide Treatment in Enzalutamide Resistant Prostate Cancer

BACKGROUND/OBJECTIVE

Prostate cancer (PCa) remains a prevalent and deadly disease, particularly in its advanced stages. Despite various available treatments, resistance to drugs like enzalutamide continues to present significant challenges. This study aimed to investigate the role of Galectin-1 (Gal-1) in enzalutamide-resistant PCa and assess its potential as a therapeutic target to overcome resistance.

METHODS

The study utilized specific siRNA-mediated knockdown of Gal-1 in enzalutamide-resistant PCa cells to evaluate its effects on cell proliferation and response to enzalutamide treatment. An orthotopic mouse model was employed to examine the in vivo impact of Gal-1 knockdown. Pharmacological targeting of Gal-1 was conducted using LLS30, and its effects were assessed both in vitro and in vivo. RNA sequencing (RNA-seq) analysis was performed to explore the molecular mechanisms underlying the observed effects.

RESULTS

The findings demonstrated significant upregulation of Gal-1 in enzalutamide-resistant PCa cells. Gal-1 knockdown inhibited cell proliferation and resensitized resistant cells to enzalutamide treatment in the orthotopic mouse model. Elevated levels of androgen receptor full-length and AR-V7 are key mechanisms under-lying resistance to enzalutamide in PCa. Gal-1 knockdown suppressed AR and AR-V7 expression and their transcriptional activity. Treatment with LLS30 significantly suppressed the growth of enzalutamide-resistant PCa cells and exhibited synergistic effects when combined with enzalutamide. Notably, this combination therapy significantly inhibited the growth of enzalutamide-resistant xenografts in vivo. RNA-seq analysis revealed that LLS30 modulates AR and AR-V7 signaling through the inhibition of associated target genes.

CONCLUSION

These findings highlight Gal-1 as a promising therapeutic target for overcoming enzalutamide resistance in PCa. Targeting the Gal-1/AR/AR-V7 axis with LLS30 presents a novel strategy to enhance enzalutamide efficacy and address drug resistance in advanced PCa.

Deciphering the Liaison Between Fine Particulate Matter Pollution, Oxidative Stress, and Prostate Cancer: Where Are We Now?

Prostate cancer (PCa), a highly prevalent cancer in men worldwide, is projected to rise in the coming years. As emerging data indicate the carcinogenic effects of fine particulate matter (PM2.5) in lung cancer and other site-specific cancers, there is an urgent need to evaluate the relationship between this environmental risk factor and PCa as a potential target for intervention. The present review provides up-to-date evidence about the impact of airborne PM2.5 pollution on the initiation and progression of PCa. Examining the composition and characteristics of PM2.5 reveals its ability to induce toxic effects, inflammatory injuries, and oxidative damages. Additionally, PM2.5 can attach to endocrine-disrupting chemicals implicated in prostatic carcinogenesis. Considering the potential significance of oxidative stress in the risk of the disease, our review underlines the protective strategies, such as antioxidant-based approaches, for individuals exposed to increased PM2.5 levels. Moreover, the findings call for further research to understand the associations and mechanisms linking PM2.5 exposure to PCa risk as well as to suggest appropriate measures by policymakers, scientific researchers, and healthcare professionals in order to address this global health issue.

Clinical characteristics and survival of patients with de novo metastatic prostate cancer treated with androgen deprivation therapy and taxane-based chemotherapy in Uganda: a retrospective study

BACKGROUND

Prostate cancer is the second most common cancer among men worldwide. Mortality is highest among patients in resource-limited settings (RLS), in part due to late-stage disease. Among patients with metastatic prostate cancer (mPCa), studies have shown significant improvement in overall survival with the use of androgen deprivation therapy (ADT) and taxane-based chemotherapy. However, outcome data among patients treated with chemo-endocrine therapy are scarce in many resource-limited settings. The aim of this study was to determine the clinical characteristics and 5-year overall survival (OS) of patients with de novo mPCa treated at the Uganda Cancer Institute (UCI).

METHODS

A retrospective chart review study was conducted between 2015 and 2019, and the data of patients with histologically confirmed prostate cancer and radiological evidence of metastasis were reviewed. Sample size was estimated for Cox Proportion Hazard regression. Data on clinical and laboratory characteristics, overall survival, and predictors of survival were extracted. P < 0.05 was considered to indicate statistical significance.

RESULTS

A total of 300 patients were enrolled over the 5-year study period. The median age was 68 (IQR 61.5-74) years. At presentation, lower urinary tract symptoms were reported in nearly all patients (96.7%, n = 290), median total prostate specific antigen (PSA) was 414.75 ng/ml and 40% (n = 120) of patients had grade 5 histological scores. In addition to receiving ADT, majority of patients (70.3%, n = 211) received at least 6 cycles of chemotherapy. Overall survival at one year was 92.4% (95% CI: 88.6-94.9%), but it declined to 45.2% (95% CI: 36.8-53.2%) at 5 years. A high Gleason score, the presence of visceral metastasis and receiving less than 6 cycles of chemotherapy were predictors of poor outcomes.

CONCLUSION

Patients with de novo mPCa in Uganda present with high histologic grades and high baseline Prostate Specific Antigen (PSA) levels but have improved 5-year overall survival with a combination of chemotherapy and ADT as a first-line treatment. We recommend interventions to reduce late presentation and prospective studies to evaluate treatment efficacy in this population.

PSA, an outdated biomarker for prostate cancer: In search of a more specific biomarker, citrate takes the spotlight

The prevailing biomarker employed for prostate cancer (PCa) screening and diagnosis is the prostate-specific antigen (PSA). Despite excellent sensitivity, PSA lacks specificity, leading to false positives, unnecessary biopsies and overdiagnosis. Consequently, PSA is increasingly less used by clinicians, thus underscoring the imperative for the identification of new biomarkers. An emerging biomarker in this context is citrate, a molecule secreted by the normal prostate, which has been shown to be inversely correlated with PCa. Here, we discuss about PSA and its usage for PCa diagnosis, its lack of specificity, and the various conditions that can affect its levels. We then provide our vision about what we think would be a valuable addition to our PCa diagnosis toolkit, citrate. We describe the unique citrate metabolic program in the prostate and how this profile is reprogrammed during carcinogenesis. Finally, we summarize the evidence that supports the usage of citrate as a biomarker for PCa diagnosis, as it can be measured in various patient samples and be analyzed by several methods. The unique relationship between citrate and PCa, combined with the stability of citrate levels in other prostate-related conditions and the simplicity of its detection, further accentuates its potential as a biomarker.

Clinicopathologic Characteristics of a Single-institution Cohort of Ovarian Adult Granulosa Cell Tumors, With Biomarker and Therapeutic Implications Utilizing the Detection of Androgen, Estrogen, and Progesterone Hormone Receptor Expression by Immunohistochemistry

Adult granulosa cell tumors (AGCTs) are rare ovarian tumors with generally good prognosis after surgical resection; however, they do have recurrence potential. Therapeutic and management options for recurrences are currently limited, and the need for expanded adjuvant therapies is increasingly recognized. Anti-hormonal therapy is being explored as an option, which relies on the detection and assessment of hormone receptor expression (androgen, estrogen, and progesterone receptors) as a biomarker and therapeutic target. Our study identifies several clinicopathologic characteristics with significant associations for recurrence of AGCT, which were younger age, higher stage, and larger tumor size. Our study also demonstrates that androgen receptor (AR) expression may be utilized as a potential biomarker for hormonal therapy and that detection of AR expression in AGCT by immunohistochemistry (IHC) varies depending on the antibody clone used for testing. AR was detected in 95% of samples tested with antibodies derived from clone AR27. This detection rate is much higher than previously reported.

Combination of Blood Adiponectin and Leptin Levels Is a Predictor of Biochemical Recurrence in Prostate Cancer Invading the Surrounding Adipose Tissue

Biochemical recurrence is a process that progresses to castration-resistant prostate cancer (CRPC) and prediction of biochemical recurrence is useful in determining early therapeutic intervention and disease treatment. Prostate cancer is surrounded by adipose tissue, which secretes adipokines, affecting cancer progression. This study aimed to investigate the correlation between blood adipokines and CRPC biochemical recurrence. We retrospectively analyzed the clinical data, including preoperative serum adipokine levels, of 99 patients with pT3a pN0 prostate cancer who underwent proctectomy between 2011 and 2019. The primary outcome was biochemical recurrence (prostate-specific antigen: PSA > 0.2). We identified 65 non-recurrences and 34 biochemical recurrences (one progressed to CRPC). The initial PSA level was significantly higher (p = 0.006), but serum adiponectin (p = 0.328) and leptin (p = 0.647) levels and their ratio (p = 0.323) were not significantly different in the biochemical recurrence group compared with the non-recurrence group. In contrast, significantly more biochemical recurrences were observed in the group with adiponectin < 6 μg/mL and Leptin < 4 ng/mL (p = 0.046), initial PSA > 15 ng/mL, clinical Gleason pattern ≥ 4, and positive resection margin. A significant difference was also observed in the multivariate analysis (hazard ratio: 4.04, 95% confidence interval: 1.21-13.5, p = 0.0232). Thus, low preoperative serum adiponectin and high leptin levels were significantly associated with biochemical recurrence in adipose tissue-invasive prostate cancer, suggesting that they may be useful predictors of biochemical recurrence. Further studies with larger cases are needed to increase the validity of this study.

Improving cancer immunotherapy in prostate cancer by modulating T cell function through targeting the galectin-1

Our study aimed to elucidate the role of Galectin-1 (Gal-1) role in the immunosuppressive tumor microenvironment (TME) of prostate cancer (PCa). Our previous findings demonstrated a correlation between elevated Gal-1 expression and advanced PCa stages. In this study, we also observed that Gal-1 is expressed around the tumor stroma and its expression level is associated with PCa progression. We identified that Gal-1 could be secreted by PCa cells, and secreted Gal-1 has the potential to induce T cell apoptosis. Gal-1 knockdown or inhibition of Gal-1 function by LLS30 suppresses T cell apoptosis resulting in increased intratumoral T cell infiltration. Importantly, LLS30 treatment significantly improved the antitumor efficacy of anti-PD-1 in vivo. Mechanistically, LLS30 binds to the carbohydrate recognition domain (CRD) of Gal-1, disrupting its binding to CD45 leading to the suppression of T cell apoptosis. In addition, RNA-seq analysis revealed a novel mechanism of action for LLS30, linking its tumor-intrinsic oncogenic effects to anti-tumor immunity. These findings suggested that tumor-derived Gal-1 contributes to the immunosuppressive TME in PCa by inducing apoptosis in effector T cells. Targeting Gal-1 with LLS30 may offer a strategy to enhance anti-tumor immunity and improve immunotherapy.

Increased circulating polymorphonuclear myeloid-derived suppressor cells are associated with prognosis of metastatic castration-resistant prostate cancer

Introduction

Myeloid-derived suppressor cell (MDSC) exhibits immunosuppressive functions and affects cancer progression, but its relationship with prostate cancer remains unclear. We elucidated the association of polymorphonuclear MDSC (PMN-MDSC) and monocytic MDSC (M-MDSC) levels of the total peripheral blood mononuclear cells (PBMCs) with prostate cancer progression and evaluated their roles as prognostic indicators.

Methods

We enrolled 115 patients with non-metastatic hormone-sensitive prostate cancer (nmHSPC, n = 62), metastatic hormone-sensitive prostate cancer (mHSPC, n = 23), and metastatic castration-resistant prostate cancer (mCRPC, n = 30). Subsequently, the proportions of MDSCs in each disease progression were compared. Log-rank tests and multivariate Cox regression analyses were performed to ascertain the associations of overall survival.

Results

The patients with mCRPC had significantly higher PMN-MDSC percentage than those with nmHSPC and mHSPC (P = 7.73 × 10-5 and 0.0014). Significantly elevated M-MDSC levels were observed in mCRPC patients aged <70 years (P = 0.016) and with a body mass index (BMI) <25 kg/m2 (P = 0.043). The high PMN-MDSC group had notably shorter median survival duration (159 days) than the low PMN-MDSC group (768 days, log-rank P = 0.018). In the multivariate analysis including age, BMI, and MDSC subset, PMN-MDSC was significantly associated with prognosis (hazard ratios, 3.48; 95% confidence interval: 1.05-11.56, P = 0.042).

Discussion

PMN-MDSC levels are significantly associated with mCRPC prognosis. Additionally, we highlight the remarkable associations of age and BMI with M-MDSC levels in mCRPC, offering novel insights into MDSC dynamics in prostate cancer progression.

Insight into Recent Advances in Degrading Androgen Receptor for Castration-Resistant Prostate Cancer

Induced protein degradation has emerged as an innovative drug discovery approach, complementary to the classical method of suppressing protein function. The androgen receptor signaling pathway has been identified as the primary driving force in the development and progression of lethal castration-resistant prostate cancer. Since androgen receptor degraders function differently from androgen receptor antagonists, they hold the promise to overcome the drug resistance challenges faced by current therapeutics. Proteolysis-targeting chimeras (PROTACs), monomeric degraders, hydrophobic tagging, molecular glues, and autophagic degradation have demonstrated their capability in downregulating intracellular androgen receptor concentrations. The potential of these androgen receptor degraders to treat castration-resistant prostate cancer is substantiated by the advancement of six PROTACs and two monomeric androgen receptor degraders into phase I or II clinical trials. Although the chemical structures, in vitro and in vivo data, and degradation mechanisms of androgen receptor degraders have been reviewed, it is crucial to stay updated on recent advances in this field as novel androgen receptor degraders and new strategies continue to emerge. This review thus provides insight into recent advancements in this paradigm, offering an overview of the progress made since 2020.

New mode of action of curcumin on prostate cancer cells: Modulation of endoplasmic reticulum-associated degradation mechanism and estrogenic signaling

Prostate cancer is leading to cancer-related mortality in numerous men each year worldwide. While there are several treatment options, acquired drug resistance mostly limits the success of treatments. Therefore, there is a need for the development of innovative treatments. Curcumin is one of the bioactive polyphenolic ingredients identified in turmeric and has numerous biological activities, such as anti-inflammatory and anticancer. In the present study, we investigated the effect of curcumin on the ER-associated degradation (ERAD) and estrogenic signaling in prostate cancer cells. The antiproliferative effect of curcumin on human androgen-dependent prostate cancer cell lines LNCaP and VCaP was estimated by WST-1 assay. Morphological alterations were investigated with an inverted microscope. We investigated the effect of curcumin on ERAD and estrogen signaling proteins by immunoblotting assay. To evaluate the impact of curcumin on endoplasmic reticulum (ER) protein quality-related, the expression level of 32 genes was analyzed by quantitative reverse transcription polymerase chain reaction. The nuclear translocation of estrogen receptor was examined by nuclear fractionation and immunofluorescence microscopy. We found that curcumin effectively reduced the proliferation rates of LNCaP and VCaP cells. ERAD proteins; Hrd1, gp78, p97/VCP, Ufd1 and Npl4 were strongly induced by curcumin. Also, the steady-state level of polyubiquitin was increased in a dose-dependent manner in both cell lines. Curcumin administration remarkably decreased the protein levels of estrogen receptor-alfa (Erα), whereas estrogen receptor-beta unaffected. Additionally, curcumin strongly restricted the nuclear translocation of Erα. Present data suggest that curcumin may be effectively used in therapeutic approaches associated with the targeting ER protein quality control mechanism and modulation of estrogen signaling in prostate cancer.

Synthesis and Anticancer Activity of Novel Derivatives of α,β-Unsaturated Ketones Based on Oleanolic Acid: in Vitro and in Silico Studies against Prostate Cancer Cells

Herein, new derivatives of α,β-unsaturated ketones based on oleanolic acid (4 a-i) were designed, synthesized, characterized, and tested against human prostate cancer (PC3). According to the in vitro cytotoxic study, title compounds (4 a-i) showed significantly lower toxicity toward healthy cells (HUVEC) in comparison with the reference drug doxorubicin. The compounds with the lowest IC50 values on PC3 cell lines were 4 b (7.785 μM), 4 c (8.869 μM), and 4 e (8.765 μM). The results of the ADME calculations showed that the drug-likeness parameters were within the defined ranges according to Lipinski's and Jorgensen's rules. For the most potent compounds 4 b, 4 c, and 4 e, a molecular docking analysis using the induced fit docking (IFD) protocol was performed against three protein targets (PARP, PI3K, and mTOR). Based on the IFD scores, compound 4 b had the highest calculated affinity for PARP1, while compound 4 c had higher affinities for mTOR and PI3K. The MM-GBSA calculations showed that the most potent compounds had high binding affinities and formed stable complexes with the protein targets. Finally, a 50 ns molecular dynamics simulation was performed to study the behavior of protein target complexes under in silico physiological conditions.

A GATA2-CDC6 axis modulates androgen receptor blockade-induced senescence in prostate cancer

BACKGROUND

Prostate cancer is a major cause of cancer morbidity and mortality in men worldwide. Androgen deprivation therapy (ADT) has proven effective in early-stage androgen-sensitive disease, but prostate cancer gradually develops into an androgen-resistant metastatic state in the vast majority of patients. According to our oncogene-induced model for cancer development, senescence is a major tumor progression barrier. However, whether senescence is implicated in the progression of early-stage androgen-sensitive to highly aggressive castration-resistant prostate cancer (CRPC) remains poorly addressed.

METHODS

Androgen-dependent (LNCaP) and -independent (C4-2B and PC-3) cells were treated or not with enzalutamide, an Androgen Receptor (AR) inhibitor. RNA sequencing and pathway analyses were carried out in LNCaP cells to identify potential senescence regulators upon treatment. Assessment of the invasive potential of cells and senescence status following enzalutamide treatment and/or RNAi-mediated silencing of selected targets was performed in all cell lines, complemented by bioinformatics analyses on a wide range of in vitro and in vivo datasets. Key observations were validated in LNCaP and C4-2B mouse xenografts. Senescence induction was assessed by state-of-the-art GL13 staining by immunocytochemistry and confocal microscopy.

RESULTS

We demonstrate that enzalutamide treatment induces senescence in androgen-sensitive cells via reduction of the replication licensing factor CDC6. Mechanistically, we show that CDC6 downregulation is mediated through endogenous activation of the GATA2 transcription factor functioning as a CDC6 repressor. Intriguingly, GATA2 levels decrease in enzalutamide-resistant cells, leading to CDC6 stabilization accompanied by activation of Epithelial-To-Mesenchymal Transition (EMT) markers and absence of senescence. We show that CDC6 loss is sufficient to reverse oncogenic features and induce senescence regardless of treatment responsiveness, thereby identifying CDC6 as a critical determinant of prostate cancer progression.

CONCLUSIONS

We identify a key GATA2-CDC6 signaling axis which is reciprocally regulated in enzalutamide-sensitive and -resistant prostate cancer environments. Upon acquired resistance, GATA2 repression leads to CDC6 stabilization, with detrimental effects in disease progression through exacerbation of EMT and abrogation of senescence. However, bypassing the GATA2-CDC6 axis by direct inhibition of CDC6 reverses oncogenic features and establishes senescence, thereby offering a therapeutic window even after acquiring resistance to therapy.

Comprehensive analysis of the progression mechanisms of CRPC and its inhibitor discovery based on machine learning algorithms

Background: Almost all patients treated with androgen deprivation therapy (ADT) eventually develop castration-resistant prostate cancer (CRPC). Our research aims to elucidate the potential biomarkers and molecular mechanisms that underlie the transformation of primary prostate cancer into CRPC. Methods: We collected three microarray datasets (GSE32269, GSE74367, and GSE66187) from the Gene Expression Omnibus (GEO) database for CRPC. Differentially expressed genes (DEGs) in CRPC were identified for further analyses, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and gene set enrichment analysis (GSEA). Weighted gene coexpression network analysis (WGCNA) and two machine learning algorithms were employed to identify potential biomarkers for CRPC. The diagnostic efficiency of the selected biomarkers was evaluated based on gene expression level and receiver operating characteristic (ROC) curve analyses. We conducted virtual screening of drugs using AutoDock Vina. In vitro experiments were performed using the Cell Counting Kit-8 (CCK-8) assay to evaluate the inhibitory effects of the drugs on CRPC cell viability. Scratch and transwell invasion assays were employed to assess the effects of the drugs on the migration and invasion abilities of prostate cancer cells. Results: Overall, a total of 719 DEGs, consisting of 513 upregulated and 206 downregulated genes, were identified. The biological functional enrichment analysis indicated that DEGs were mainly enriched in pathways related to the cell cycle and metabolism. CCNA2 and CKS2 were identified as promising biomarkers using a combination of WGCNA, LASSO logistic regression, SVM-RFE, and Venn diagram analyses. These potential biomarkers were further validated and exhibited a strong predictive ability. The results of the virtual screening revealed Aprepitant and Dolutegravir as the optimal targeted drugs for CCNA2 and CKS2, respectively. In vitro experiments demonstrated that both Aprepitant and Dolutegravir exerted significant inhibitory effects on CRPC cells (p < 0.05), with Aprepitant displaying a superior inhibitory effect compared to Dolutegravir. Discussion: The expression of CCNA2 and CKS2 increases with the progression of prostate cancer, which may be one of the driving factors for the progression of prostate cancer and can serve as diagnostic biomarkers and therapeutic targets for CRPC. Additionally, Aprepitant and Dolutegravir show potential as anti-tumor drugs for CRPC.

Adoption of Lutetium-177 PSMA radioligand therapy for metastatic castration resistant prostate cancer: a total population analysis in Germany from 2016 to 2020

PURPOSE

This study is to investigate the adoption and current trends of Lutetium-177 PSMA RLT for mCRPC in Germany.

METHODS

We analyzed data from the reimbursement.INFO tool based on German hospitals' quality reports for Lutetium-177 PSMA RLT from 2016 to 2020 and from the nationwide German hospital billing database (Destatis) for general therapy with open radionuclides in combination with prostate cancer from 2006 to 2020. For validation of these billing data, we included the 177Lu-PSMA RLT cycles from two participating institutions from 2016 to 2020. For detection of trends over time we applied linear regression models.

RESULTS

General therapy with open radionuclides increased from 2006 to 2020. We identified a total of 12,553 177Lu-PSMA RLT cycles. The number of 177Lu-PSMA RLTs steadily increased from a total of 1026 therapies in 2016 to 3328 therapies in 2020 (+ 576 RLT/year; p < 0.005). In 2016, 25 departments of nuclear medicine offered this treatment, which increased to 44 nuclear medicine departments in 2020. In 2016, 16% of nuclear medicine departments (4/25) performed more than 100 177Lu-PSMA RLTs, which increased to 36% (16/44) in 2020 (p < 0.005). In 2016, 88% (22/25) of 177Lu-PSMA RLTs were performed at a university hospital, which decreased to 70% (31/44) in 2020. The proportion of patients older than 65 years receiving 177Lu-PSMA RLT increased from 78% in 2016 to 81% in 2020.

CONCLUSION

Treatment of mCRPC with 177Lu-PSMA RLT has been rapidly increasing in Germany in the recent years providing an additional therapy option. This development is remarkable, because of outstanding formal EMA approval.

Preclinical patient-derived modeling of castration-resistant prostate cancer facilitates individualized assessment of homologous recombination repair deficient disease

The use of mutation analysis of homologous recombination repair (HRR) genes to estimate PARP-inhibition response may miss a larger proportion of responding patients. Here, we provide preclinical models for castration-resistant prostate cancer (CRPC) that can be used to functionally predict HRR defects. In vitro, CRPC LNCaP sublines revealed an HRR defect and enhanced sensitivity to olaparib and cisplatin due to impaired RAD51 expression and recruitment. Ex vivo-induced castration-resistant tumor slice cultures or tumor slice cultures derived directly from CRPC patients showed increased olaparib- or cisplatin-associated enhancement of residual radiation-induced γH2AX/53BP1 foci. We established patient-derived tumor organoids (PDOs) from CRPC patients. These PDOs are morphologically similar to their primary tumors and genetically clustered with prostate cancer but not with normal prostate or other tumor entities. Using these PDOs, we functionally confirmed the enhanced sensitivity of CRPC patients to olaparib and cisplatin. Moreover, olaparib but not cisplatin significantly decreased the migration rate in CRPC cells. Collectively, we present robust patient-derived preclinical models for CRPC that recapitulate the features of their primary tumors and enable individualized drug screening, allowing translation of treatment sensitivities into tailored clinical therapy recommendations.

Repression of SLC22A3 by the AR-V7/YAP1/TAZ axis in enzalutamide-resistant castration-resistant prostate cancer

Metastatic castration-resistant prostate cancer (mCRPC) is an aggressive and fatal disease, with most patients succumbing within 1-2 years despite undergoing multiple treatments. Androgen-receptor (AR) inhibitors, including enzalutamide (ENZ), are used for the treatment of mCRPC; however, most patients develop resistance to ENZ. Herein, we propose that the repression of SLC22A3 by AR-V7/YAP1/TAZ conferred ENZ resistance in mCRPC. SLC22A3 expression is specifically downregulated in the ENZ-resistant C4-2B MDVR cells, and when YAP1/TAZ is hyperactivated by AR full-length or AR-V7, these proteins interact with DNMT1 to repress SLC22A3 expression. We observed low SLC22A3 expression and high levels of TAZ or YAP1 in mCRPC patient tissues harbouring AR-V7 and the opposite expression patterns in normal patient tissues. Our findings suggest a mechanism underlying ENZ resistance by providing evidence that the AR-V7/YAP1/TAZ axis represses SLC22A3, which could be a potential treatment target in prostate cancer.

STEAP1 regulation and its influence modulating the response of LNCaP prostate cancer cells to bicalutamide, enzalutamide and apalutamide

Anti‑androgen drugs are the standard pharmacological therapies for treatment of non‑metastatic prostate cancer (PCa). However, the response of PCa cells may depend on the anti‑androgen used and often patients become resistant to treatment. Thus, studying how the anti‑androgen drugs affect oncogenes expression and action and the identification of the best strategy for combined therapies are essential to improve the efficacy of treatments. The Six Transmembrane Epithelial Antigen of the Prostate 1 (STEAP1) is an oncogene associated with PCa progression and aggressiveness, although its relationship with the androgen receptor signaling remains to be elucidated. The present study aimed to evaluate the effect of anti‑androgens in regulating STEAP1 expression and investigate whether silencing STEAP1 can make PCa cells more sensitive to anti‑androgen drugs. For this purpose, wild‑type and STEAP1 knockdown LNCaP cells were exposed to bicalutamide, enzalutamide and apalutamide. Bicalutamide decreased the expression of STEAP1, but enzalutamide and apalutamide increased its expression. However, decreased cell proliferation and increased apoptosis was observed in response to all drugs. Overall, the cellular and molecular effects were similar between LNCaP wild‑type and LNCaP‑STEAP1 knockdown cells, except for c‑myc expression levels, where a cumulative effect between anti‑androgen treatment and STEAP1 knockdown was observed. The effect of STEAP1 knockdown alone or combined with anti‑androgens in c‑myc levels is required to be addressed in future studies.

Dissecting the effects of androgen deprivation therapy on cadherin switching in advanced prostate cancer: A molecular perspective

Prostate cancer is one of the most often diagnosed malignancies in males and its prevalence is rising in both developed and developing countries. Androgen deprivation therapy has been used as a standard treatment approach for advanced prostate cancer for more than 80 years. The primary aim of androgen deprivation therapy is to decrease circulatory androgen and block androgen signaling. Although a partly remediation is accomplished at the beginning of treatment, some cell populations become refractory to androgen deprivation therapy and continue to metastasize. Recent evidences suggest that androgen deprivation therapy may cause cadherin switching, from E-cadherin to N-cadherin, which is the hallmark of epithelial-mesenchymal transition. Diverse direct and indirect mechanisms are involved in this switching and consequently, the cadherin pool changes from E-cadherin to N-cadherin in the epithelial cells. Since E-cadherin represses invasive and migrative behaviors of the tumor cells, the loss of E-cadherin disrupts epithelial tissue structure leading to the release of tumor cells into surrounding tissues and circulation. In this study, we review the androgen deprivation therapy-dependent cadherin switching in advanced prostate cancer with emphasis on its molecular basis especially the transcriptional factors regulated through TFG-β pathway.

Differences in Prostate Cancer Transcriptomes by Age at Diagnosis: Are Primary Tumors from Older Men Inherently Different?

Older age at diagnosis is consistently associated with worse clinical outcomes in prostate cancer. We sought to characterize gene expression profiles of prostate tumor tissue by age at diagnosis. We conducted a discovery analysis in The Cancer Genome Atlas prostate cancer dataset (n = 320; 29% of men >65 years at diagnosis), using linear regressions of age at diagnosis and mRNA expression and adjusting for TMPRSS2:ERG fusion status and race. This analysis identified 13 age-related candidate genes at FDR < 0.1, six of which were also found in an analysis additionally adjusted for Gleason score. We then validated the 13 age-related genes in a transcriptome study nested in the Health Professionals Follow-up Study and Physicians' Health Study (n = 374; 53% of men >65 years). Gene expression differences by age in the 13 candidate genes were directionally consistent, and age at diagnosis was weakly associated with the 13-gene score. However, the age-related genes were not consistently associated with risk of metastases and prostate cancer-specific death. Collectively, these findings argue against tumor genomic differences as a main explanation for age-related differences in prostate cancer prognosis.

PREVENTION RELEVANCE

Older age at diagnosis is consistently associated with worse clinical outcomes in prostate cancer. This study with independent discovery and validation sets and long-term follow-up suggests that prevention of lethal prostate cancer should focus on implementing appropriate screening, staging, and treatment among older men without expecting fundamentally different tumor biology.

Spatial Profiling of the Prostate Cancer Tumor Microenvironment Reveals Multiple Differences in Gene Expression and Correlation with Recurrence Risk

The tumor microenvironment plays a crucial role in both the development and progression of prostate cancer. Furthermore, identifying protein and gene expression differences between different regions is valuable for treatment development. We applied Digital Spatial Profiling multiplex analysis to formalin-fixed paraffin embedded prostatectomy tissue blocks to investigate protein and transcriptome differences between tumor, tumor-adjacent stroma (TAS), CD45+ tumor, and CD45+ TAS tissue. Differential expression of an immunology/oncology protein panel (n = 58) was measured. OX40L and CTLA4 were expressed at higher levels while 22 other proteins, including CD11c, were expressed at lower levels (FDR < 0.2 and p-value < 0.05) in TAS as compared to tumor epithelia. A tissue microarray analysis of 97 patients with 1547 cores found positive correlations between high expression of CD11c and increased time to recurrence in tumor and TAS, and inverse relationships for CTLA4 and OX40L, where higher expression in tumor correlated with lower time to recurrence, but higher time to recurrence in TAS. Spatial transcriptomic analysis using a Cancer Transcriptome Atlas panel (n = 1825 genes) identified 162 genes downregulated and 69 upregulated in TAS versus tumor, 26 downregulated and 6 upregulated in CD45+ TAS versus CD45+ tumor. We utilized CIBERSORTx to estimate the relative immune cell fractions using CD45+ gene expression and found higher average fractions for memory B, naïve B, and T cells in TAS. In summary, the combination of protein expression differences, immune cell fractions, and correlations of protein expression with time to recurrence suggest that closely examining the tumor microenvironment provides valuable data that can improve prognostication and treatment techniques.

Discovering biomarkers for hormone-dependent tumors: in silico study on signaling pathways implicated in cell cycle and cytoskeleton regulation

Malignancies dependent on hormone homeostasis include breast, ovary, cervical, prostate, testis and uterine tumors. Hormones are involved in signal transduction which orchestrate processes, such as apoptosis, proliferation, cell cycle or cytoskeleton organization. Currently, there is a need for novel biomarkers which would help to diagnose cancers efficiently. In this study, the genes implicated in signaling that is important in hormone-sensitive carcinogenesis were investigated regarding their prognostic significance. Data of seven cancer cohorts were collected from FireBrowse. 54 gene sets implicated in specific pathways were browsed through MSig database. Profiling was assessed via Monocle3, while gene ontology through PANTHER. For confirmation, correlation analysis was performed using WGCNA. Protein-protein networks were visualized via Cytoscape and impact of genes on survival, as well as cell cycle or cytoskeleton-related prognostic signatures, was tested. Several differences in expression profile were identified, some of them allowed to distinguish histology. Functional annotation revealed that various regulation of cell cycle, adhesion, migration, apoptosis and angiogenesis underlie these differences. Clinical traits, such as histological type or cancer staging, were found during evaluation of module-trait relationships. Of modules, the TopHubs (COL6A3, TNR, GTF2A1, NKX3-1) interacted directly with, e.g., PDGFB, ITGA10, SP1 or AKT3. Among TopHubs and interacting proteins, many showed an impact on hazard ratio and affected the cell cycle or cytoskeleton-related prognostic signatures, e.g., COL1A1 or PDGFB. In conclusion, this study laid the foundation for further hormone-sensitive carcinogenesis research through identification of genes which prove that crosstalk between cell cycle and cytoskeleton exists, opening avenues for future therapeutic strategies.

Reovirus mutant jin-3 exhibits lytic and immune-stimulatory effects in preclinical human prostate cancer models

Treatment of castration-resistant prostate cancer remains a challenging clinical problem. Despite the promising effects of immunotherapy in other solid cancers, prostate cancer has remained largely unresponsive. Oncolytic viruses represent a promising therapeutic avenue, as oncolytic virus treatment combines tumour cell lysis with activation of the immune system and mounting of effective anti-tumour responses. Mammalian Orthoreoviruses are non-pathogenic human viruses with a preference of lytic replication in human tumour cells. In this study, we evaluated the oncolytic efficacy of the bioselected oncolytic reovirus mutant jin-3 in multiple human prostate cancer models. The jin-3 reovirus displayed efficient infection, replication, and anti-cancer responses in 2D and 3D prostate cancer models, as well as in ex vivo cultured human tumour slices. In addition, the jin-3 reovirus markedly reduced the viability and growth of human cancer cell lines and patient-derived xenografts. The infection induced the expression of mediators of immunogenic cell death, interferon-stimulated genes, and inflammatory cytokines. Taken together, our data demonstrate that the reovirus mutant jin-3 displays tumour tropism, and induces potent oncolytic and immunomodulatory responses in human prostate cancer models. Therefore, jin-3 reovirus represents an attractive candidate for further development as oncolytic agent for treatment of patients with aggressive localised or advanced prostate cancer.

Mechanistic Insights into the Selective Dual BET and PLK1 Inhibitory Activity of a Novel Benzamide Compound in Castration-Resistant Prostrate Cancer

Though multifactorial, BET and PLK1 proteins have been found to be key players in the oncogenic process leading to castration-resistant prostate cancer through regulation of AR and MYC-mediated transcription. Hence, dual inhibition of these proteins appears to be an auspicious approach for CRPC therapy. WNY0824 has been reported to exhibit nanomolar range inhibition as well as significant anti-proliferative activity on AR-positive CRPC cells in vitro. However, structural, and mechanistic events associated with its dual inhibitory and anti-proliferative mechanisms remain unclear. Utilizing integrative computer-assisted atomistic techniques, analyses revealed that the dual-inhibitory activity of WNY0824 against BRD4 and PLK1 proteins is mediated by conserved residues present in the binding cavities of both proteins which are shown to elicit various strong intermolecular interactions and thus favour binding affinity. Also, binding orientation of the ligand at the protein binding cavities allowed for important hydrophobic interactions which resulted in high binding free energy of -42.50 kcal/mol and -51.64 kcal/mol towards BRD4 and PLK1, respectively. While van der Waals interactions are very important to ligand binding in BRD4-WNY complex, electrostatic interactions are pertinent to PLK1-WNY complex. Intriguingly, WNY0824 triggered conformational alterations in both proteins through increased structural instability, decreased structural compactness and mitigation in exposure of residues to solvent surface area. Consequently, critical interactions peculiar to the oncogenic activities of BRD4 and PLK1 were inhibited, a phenomenon that results in an antagonism of CRPC progression. The mechanistic insights presented in this report would further assist in the structure-based design of improved inhibitors useful in CRPC therapy.

Synthesis and preliminary exploration of a NIR fluorescent probe for the evaluation of androgen dependence of prostate cancer

PURPOSE

Castration resistance prostate cancer patients showing resistance to the androgen deprivation therapy always have low five-year survival rate and worse prognosis. A responsive NIR fluorescent probe was designed to report the androgen dependence and monitor the development of castration resistance for prostate cancer.

METHODS

Intratumoral H₂S in prostate cancer was closely related to castration resistance. A H₂S-responsive NIR probe (HM) was developed as a dependent indicator to report the androgen dependence of prostate cancer. The specificity of HM to H₂S and the influence of normal intracellular substrates to the response between H₂S and HM were determined. Cell/in vivo animal imaging were performed on PC-3 and LnCAP cell/tumor bearing mice, which presented with androgen independence and androgen dependence, respectively.

RESULTS

When HM responded to H₂S, strong fluorescence at 770 nm could be rapidly turned on in 5 min with the stokes shift as large as 200 nm. The recognition between HM and H₂S showed high specificity. Neither other common substrates showed capacity to turn on HM's fluorescence, nor their existence demonstrated competition. The fluorescence intensity was linearly dependent to the H₂S concentration and the limited of detection was 0.15 μM. When HM was applied to PC-3/LNCaP prostate cancer cell and tumor, the intracellular and intratumoral H₂S could be clearly imaged and monitored.

CONCLUSION

HM showing obvious fluorescent behaviors in androgen dependence and independence prostate tumor, which could work as an indicator to reported the androgen dependence of prostate cancer and monitor the development of castration resistance.

Studies of hormonal regulation, phenotype plasticity, bone metastasis, and experimental therapeutics in androgen-repressed human prostate cancer (ARCaP) model

First established by Dr. Leland W. K. Chung's lab, the androgen-repressed prostate cancer cell (ARCaP) line is derived from the ascitic fluid of a prostate cancer (PCa) patient with widely metastatic disease. Based on its unique characteristic of growth suppression in the presence of androgen, ARCaP cell line has contributed to the research of PCa disease progression toward therapy- and castration-resistant PCa (t-CRPC). It has been widely applied in studies exploring experimental therapeutic reagents including Genistein, Vorinostat and Silibinin. ARCaP cells have showed increased metastatic potential to the bone and soft tissues. In addition, accumulating studies using ARCaP model have demonstrated the epithelial-to-mesenchymal transitional plasticity of PCa using epithelial-like ARCaP_E line treated in vitro with growth factors derived from bone microenvironment. The resulting mesenchymal-like ARCaP_M sub-clone derived from bone-metastasized tumor has high expression of several factors correlated with cancer metastasis, such as N-Cadherin, Vimentin, MCM3, Granzyme B, β2-microglobulin and RANKL. In particular, the increased secretion of RANKL in ARCaP_M further facilitates its capacity of inducing osteoclastogenesis at the bone microenvironment, leading to bone resorption and tumor colonization. Meanwhile, sphingosine kinase 1 (SphK1) acts as a key molecule driver in the neuroendocrine differentiation (NED) of ARCaP sublines, suggesting the unique facet of ARCaP cells for insightful studies in more malignant neuroendocrine prostate cancer (NEPC). Overall, the establishment of ARCaP line has provided a valuable model to explore the mechanisms underlying PCa progression toward metastatic t-CRPC. In this review, we will focus on the contribution of ARCaP model in PCa research covering hormone receptor activity, skeletal metastasis, plasticity of epithelial-to-mesenchymal transition (EMT) and application of therapeutic strategies.

Androgen receptor expression in breast cancer: Implications on prognosis and treatment, a brief review

Approximately 70%-85% of breast cancers express androgen receptors (ARs). The role of AR in breast cancer pathogenesis is currently in exploration. Both androgens and anti-androgens have demonstrated variable inhibitory and stimulatory effects in AR-positive breast cancer depending on estrogen receptor and HER2 co-expression. Androgen signaling pathways interact with other critical cellular pathways, such as the PI3K/AKT/mTOR, Ras/Raf/MAPK/ERK, Wnt/β-catenin, and estrogen signaling pathways. Therapeutic exploitation of AR has been the crux of management of prostate cancer for decades. In recent years there has been increasing interest in AR as a novel therapeutic target in breast cancer. There have been many early phase clinical trials evaluating the safety and efficacy of various AR-targeted agents in breast cancer. Some of these studies have shown promising clinical benefits. Studies of biomarkers to identify the patients likely to benefit from AR-targeted therapies are currently in progress. Besides, AR expression may be an important prognostic and predictive marker for breast cancer, which needs to be defined better in future studies.

Pyridine moiety: An insight into recent advances in treatment of cancer

The incidence of cancer is increasing worldwide, affecting a vast majority of the human population. As new different anticancer agents are being developed now, the requirement is to deal somehow with them and evaluate their safety. Among them, pyridine based drugs are contributing a lot, as it is one of the imperative pharmacophores occurring synthetically as well as naturally in heterocyclic compounds, and having a wide range of therapeutic applications in the area of drug discovery, thereby offering many chances for further improvement in antitumor agents via acting onto numerous receptors of extreme prominence. Many pyridine derivatives have been reported to inhibit enzymes, receptors and many other targets for controlling and curing the global health issue of cancer. Nowadays, in combination with other moieties, researchers are focusing on the development of pyridine-based new derivatives for cancer treatment. Therefore, this review sheds light on the recent therapeutic expansions of pyridine together with its molecular docking, structure-activity-relationship, availability in the market, and a summary of recently patented and published research works that shall jointly help the scientists to produce effective drugs with the desired pharmacological activity.

PTBP1 Genetic Variants Affect the Clinical Response to Androgen-deprivation Therapy in Patients With Prostate Cancer

BACKGROUND/AIM

Heterogeneous nuclear ribonucleoproteins (hnRNPs) contribute to multiple cellular functions including RNA splicing, stabilization, transcriptional and translational regulation, and signal transduction. However, the prognostic importance of genetic variants of hnRNP genes in clinical outcomes of prostate cancer remains to be elucidated.

PATIENTS AND METHODS

We studied the association of 78 germline single-nucleotide polymorphisms (SNPs) in 23 hnRNP genes with the overall survival (OS), cancer-specific survival (CSS), and progression-free survival (PFS) in 630 patients with prostate cancer receiving androgen-deprivation therapy (ADT).

RESULTS

PTBP1 rs10420407 was the most significant SNP (false discovery rate q=0.003) and carriers of the A allele exhibited poor OS, CSS, and PFS. Multivariate Cox analysis confirmed PTBP1 rs10420407 A allele was an independent negative prognostic factor for OS and PFS. Expression quantitative trait loci analysis showed that the rs10420407 A allele had a trend towards increased PTBP1 mRNA expression, and higher expression was correlated with prostate cancer aggressiveness and poor patient prognosis. Meta-analysis of 16 independent studies further indicated a tumorigenic effect of PTBP1, with a higher expression in prostate cancers than in adjacent normal tissues (p<0.001).

CONCLUSION

Our data suggest that PTBP1 rs10420407 may influence patient response to ADT, and PTBP1 may be involved in the pathogenesis of prostate cancer progression.

Consensus on the Treatment and Follow-Up for Metastatic Castration-Resistant Prostate Cancer: A Report From the First Global Prostate Cancer Consensus Conference for Developing Countries (PCCCDC)

PURPOSE

To present a summary of the recommendations for the treatment and follow-up for metastatic castration-resistant prostate cancer (mCRPC) as acquired through a questionnaire administered to 99 physicians working in the field of prostate cancer in developing countries who attended the Prostate Cancer Consensus Conference for Developing Countries.

METHODS

A total of 106 questions out of more than 300 questions addressed the use of imaging in staging mCRPC, treatment recommendations across availability and response to prior drug treatments, appropriate drug treatments, and follow-up, and those same scenarios when limited resources needed to be considered. Responses were compiled and the percentages were presented by clinicians to support each response. Most questions had five to seven relevant options for response including abstain and/or unqualified to answer, or in the case of yes or no questions, the option to abstain was offered.

RESULTS

Most of the recommendations from this panel were in line with prior consensus, including the preference of a new antiandrogen for first-line therapy of mCRPC. Important aspects highlighted in the scenario of limited resources included the option of docetaxel as treatment preference as first-line treatment in several scenarios, docetaxel retreatment, consideration for reduced doses of abiraterone, and alternative schedules of an osteoclast-targeted therapy.

CONCLUSION

There was wide-ranging consensus in the treatment for men with mCRPC in both optimal and limited resource settings.

SWATH-MS Based Proteomic Profiling of Prostate Cancer Cells Reveals Adaptive Molecular Mechanisms in Response to Anti-Androgen Therapy

Prostate cancer (PCa) is the second most common cancer affecting men worldwide. PCa shows a broad-spectrum heterogeneity in its biological and clinical behavior. Although androgen targeted therapy (ATT) has been the mainstay therapy for advanced PCa, it inevitably leads to treatment resistance and progression to castration resistant PCa (CRPC). Thus, greater understanding of the molecular basis of treatment resistance and CRPC progression is needed to improve treatments for this lethal phenotype. The current study interrogated both proteomics and transcriptomic alterations stimulated in AR antagonist/anti-androgen (Bicalutamide and Enzalutamide) treated androgen-dependent cell model (LNCaP) in comparison with androgen-independent/castration-resistant cell model (C4-2B). The analysis highlighted the activation of MYC and PSF/SFPQ oncogenic upstream regulators in response to the anti-androgen treatment. Moreover, the study revealed anti-androgen induced genes/proteins related to transcription/translation regulation, energy metabolism, cell communication and signaling cascades promoting tumor growth and proliferation. In addition, these molecules were found dysregulated in PCa clinical proteomic and transcriptomic datasets, suggesting their potential involvement in PCa progression. In conclusion, our study provides key molecular signatures and associated pathways that might contribute to CRPC progression despite treatment with anti-androgens. Such molecular signatures could be potential therapeutic targets to improve the efficacy of existing therapies and/or predictive/prognostic value in CRPC for treatment response.

Down regulation of U2AF1 promotes ARV7 splicing and prostate cancer progression

The present study aims to investigate the roles of U2 Small Nuclear RNA Auxiliary Factor 1 (U2AF1) in the resistance to anti-androgen treatment in prostate cancer and its underlying mechanism. U2AF1 and androgen receptor variant 7 (ARV7) knockdown and overexpression were introduced in PC3 and DU145 cells. In addition, a bicalutamide-resistant PC3 (PC3 BR) cell line was also constructed. Cell count, MTT and soft agar colony formation assays were performed to evaluate cell proliferation. qRT-PCR was applied to determine the mRNA levels of U2AF1, ARV7 and Mitogen-Activated Protein Kinase 1 (MAPK1). Western blot was used to determine the MAPK1 protein expression. A negative correlation between ARV7 and U2AF1 in prostate tumor tissues was observed. U2AF1 downregulation was correlated with poor prognosis in prostate cancer patients. U2AF1 exhibited a negative correlation with ARV7 and its downregulation promoted prostate cancer cell proliferation and bicalutamide resistance. The regulatory effects of U2AF1 on ARV7 splicing were associated with MAPK1. U2AF1 affected prostate cancer proliferation and anti-androgen resistance by regulating ARV7 splicing.

The use of zebrafish model in prostate cancer therapeutic development and discovery

Zebrafish is now among the leading in vivo model for cancer research, including prostate cancer. They are an alternative economic model being used to study cancer development, proliferation, and metastasis. They can also be effectively utilized for the development of cancer drugs at all levels, including target validation, and high-throughput screening for possible lead molecules. In this review, we provide a comprehensive overview of the role of zebrafish as an in vivo model in prostate cancer research. Globally, prostate cancer is a leading cause of death in men. Although many molecular mechanisms have been identified as playing a role in the pathogenesis of prostate cancer, there is still a significant need to understand the initial events of the disease. Furthermore, current treatments are limited by the emergence of severe toxicities and multidrug resistance. There is an essential need for economical and relevant research tools to improve our understanding and overcome these problems. This review provides a comprehensive summary of studies that utilized zebrafish for different aims in prostate cancer research. We discuss the use of zebrafish in prostate cancer cell proliferation and metastasis, defining signaling pathways, drug discovery and therapeutic development against prostate cancer, and toxicity studies. Finally, this review highlights limitations in this field and future directions to efficiently use zebrafish as a robust model for prostate cancer therapeutics development.

Imipramine Inhibits Migration and Invasion in Metastatic Castration-Resistant Prostate Cancer PC-3 Cells via AKT-Mediated NF-κB Signaling Pathway

Imipramine (IMI) is a tricyclic synthetic antidepressant that is used to treat chronic psychiatric disorders, including depression and neuropathic pain. IMI also has inhibitory effects against various cancer types, including prostate cancer; however, the mechanism of its anticancer activity is not well understood. In the present study, we investigated the antimetastatic and anti-invasive effects of IMI in metastatic castration-resistant prostate cancer PC-3 cells, with an emphasis on the serine/threonine protein kinase AKT-mediated nuclear factor kappa B (NF-κB) signaling pathway. While IMI did not induce cell death, it attenuated PC-3 cell proliferation. According to the wound healing assay and invasion assay, migration and invasion in PC-3 cells were significantly inhibited by IMI in a dose-dependent manner. IMI significantly downregulated p-AKT protein expression but upregulated phospho-extracellular signal-regulated kinase (ERK1)/2 protein expression levels. Furthermore, IMI treatment resulted in decreased AKT-mediated downstream signaling, including p-inhibitor of κB kinase (IKK)α/β, p-inhibitor of κB (IκBα), and p-p65. Inhibited NF-κB signaling reduced the secretion of several proinflammatory cytokines and chemokine by PC-3 cells. Overall, our study explored the negative correlation between the use of antidepressants and prostate cancer progression, showing that IMI attenuated cell viability, migration, and invasion of PC-3 cells by suppressing the expression of AKT and NF-κB-related signaling proteins and secretion of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and monocyte chemoattractant protein-1 (MCP-1).

Determining the prognostic significance of IKKα in prostate cancer

BACKGROUND

As the survival of castration-resistant prostate cancer (CRPC) remains poor, and the nuclear factor-κB (NF-κB) pathways play key roles in prostate cancer (PC) progression, several studies have focused on inhibiting the NF-κB pathway through generating inhibitory κB kinase subunit α (IKKα) small molecule inhibitors. However, the identification of prognostic markers able to discriminate which patients could benefit from IKKα inhibitors is urgently required. The present study investigated the prognostic value of IKKα, IKKα phosphorylated at serine 180 (p-IKKα S180) and threonine 23 (p-IKKα T23), and their relationship with the androgen receptor (AR) and Ki67 proliferation index to predict patient outcome.

METHODS

A cohort of 115 patients with hormone-naïve PC (HNPC) and CRPC specimens available were used to assess tumor cell expression of proteins within both the cytoplasm and the nucleus by immunohistochemistry. The expression levels were dichotomized (low vs high) to determine the associations between IKKα, AR, Ki67, and patients'Isurvival. In addition, an analysis was performed to assess potential IKKα associations with clinicopathological and inflammatory features, and potential IKKα correlations with other cancer pathways essential for CRPC growth.

RESULTS

High levels of cytoplasmic IKKα were associated with a higher cancer-specific survival in HNPC patients with low AR expression (hazards ratio [HR], 0.33; 95% confidence interval [CI] log-rank, 0.11-0.98; P = .04). Furthermore, nuclear IKKα (HR, 2.60; 95% CI, 1.27-5.33; P = .01) and cytoplasmic p-IKKα S180 (HR, 2.10; 95% CI, 1.17-3.76; P = .01) were associated with a lower time to death from recurrence in patients with CRPC. In addition, high IKKα expression was associated with high levels of T-cells (CD3+ P = .01 and CD8+ P = .03) in HNPC; however, under castration conditions, high IKKα expression was associated with high levels of CD68+ macrophages (P = .04), higher Gleason score (P = .01) and more prostate-specific antigen concentration (P = .03). Finally, we identified crosstalk between IKKα and members of the canonical NF-κB pathway in the nucleus of HNPC. Otherwise, IKKα phosphorylated by noncanonical NF-κB and Akt pathways correlated with members of the canonical NF-κB pathway in CRPC.

CONCLUSION

The present study reports that patients with CRPC expressing high levels of nuclear IKKα or cytoplasmic p-IKKα S180, which associated with a lower time to death from recurrence, may benefit from IKKα inhibitors.

Genome-wide gene expression analysis of a murine model of prostate cancer progression: Deciphering the roles of IL-6 and p38 MAPK as potential therapeutic targets

BACKGROUND

Prostate cancer (PCa) is the most commonly diagnosed cancer and the second leading cause of cancer-related deaths among adult males globally. The poor prognosis of PCa is largely due to late diagnosis of the disease when it has already progressed to an advanced stage marked by androgen-independence, thus necessitating new strategies for early detection and treatment. We construe that these direly needed advances are limited by our poor understanding of early events in the progression of PCa and that would thus represent ideal targets for early intervention. To begin to fill this void, we interrogated molecular "oncophenotypes" that embody the transition of PCa from an androgen-dependent (AD) to-independent (AI) state.

METHODS

To accomplish this aim, we used our previously established AD and AI murine PCa cell lines, PLum-AD and PLum-AI, respectively, which recapitulate primary and progressive PCa morphologically and molecularly. We statistically surveyed global gene expressions in these cell lines by microarray analysis. Differential profiles were functionally interrogated by pathways, gene set enrichment and topological gene network analyses.

RESULTS

Gene expression analysis of PLum-AD and PLum-AI transcriptomes (n = 3 each), revealed 723 differentially expressed genes (392 upregulated and 331 downregulated) in PLum-AI compared to PLum-AD cells. Gene set analysis demonstrated enrichment of biological functions and pathways in PLum-AI cells that are central to tumor aggressiveness including cell migration and invasion facilitated by epithelial-to-mesenchymal transition (EMT). Further analysis demonstrated that the p38 mitogen-activated protein kinase (MAPK) was predicted to be significantly activated in the PLum-AI cells, whereas gene sets previously associated with favorable response to the p38 inhibitor SB203580 were attenuated (i.e., inversely enriched) in the PLum-AI cells, suggesting that these aggressive cells may be therapeutically vulnerable to p38 inhibition. Gene set and gene-network analysis also alluded to activation of other signaling networks particularly those associated with enhanced EMT, inflammation and immune function/response including, but not limited to Tnf, IL-6, Mmp 2, Ctgf, and Ptges. Accordingly, we chose SB203580 and IL-6 to validate their effect on PLum-AD and PLum-AI. Some of the common genes identified in the gene-network analysis were validated at the molecular and functional level. Additionally, the vulnerability to SB203580 and the effect of IL-6 were also validated on the stem/progenitor cell population using the sphere formation assay.

CONCLUSIONS

In summary, our study highlights pathways associated with an augmented malignant phenotype in AI cells and presents new high-potential targets to constrain the aggressive malignancy seen in the castration-resistant PCa.

Targeting Wnt/EZH2/microRNA-708 signaling pathway inhibits neuroendocrine differentiation in prostate cancer

Prostate cancer (PC) castration resistance has been linked to the differentiation of PC luminal cells into hormone-refractory neuroendocrine (NE) cells. However, the molecular mechanisms controlling the emergence of lethal NE prostate cancer (NEPC) remain unclear. The present study aimed to investigate the mechanisms underlying the transition from prostate adenocarcinoma to NEPC. The microRNA miR-708 was involved in NE differentiation and was downregulated in NEPC cells and tumor specimens. miR-708 targeted Sestrin-3 to inhibit Forkhead Box O1 (FOXO1) phosphorylation, resulting in apoptosis of prostate adenocarcinoma cells and AKT-inactivated NEPC cells, the latter of which was consistent with the progression of tumor xenografts in mice under miR-708 treatment. In silico analysis of PC and NEPC tumor specimens suggested that the polycomb repressive complex subunit Enhancer of zeste homolog 2 (EZH2) was particularly overexpressed in NEPC. Notably, EZH2 bound to the miR-708 promoter and induced its silencing in NEPC. Inhibition of EZH2 prevented NE differentiation of PC cells. EZH2 expression was regulated by both Cyclin Dependent Kinase 1 (CDK1) and Wnt signaling. Silencing transcription factor 4 (TCF4), as a key protein in Wnt signaling, prevented NEPC formation. These results provide a molecular basis for the roles of miR-708 and EZH2 in NE differentiation in PC and highlight a new paradigm in NEPC formation and survival.

Ambra1 induces autophagy and desensitizes human prostate cancer cells to cisplatin

Prostate cancer (PCa), the second most mortal cancer from developed countries, presents a high level of chemoresistance. There is emerging evidence underscores the critical role of autophagy in the onset, progression, and chemoresistance of PCa. In the present study, we investigated the possible role of a novel autophagy regulator, activating molecule in beclin1-regulated autophagy1 (Ambra1), a novel ATG gene in the sensitivity or PCa cells to cisplatin. We explored the regulation by the Ambra1 manipulation on the induction of apoptosis and autophagy in human PCa DU145 cells in the presence of cisplatin, via up- or down-regulating Ambra1 expression. In addition, we examined the colony forming of DU145 cells post cisplatin treatment and Ambra1 manipulation. Our results demonstrated that the Ambra1 up-regulation reduced, whereas Ambra1 knockdown increased the cisplatin-induced apoptosis, caspase 3 cleavage, and poly ADP-ribose polymerase (PARP) cleavage. Interestingly, we also found significant autophagy induction in the cisplatin-treated DU145 cells, with increased autophagic vesicles, up-regulated autophagy-related markers. However, the cisplatin-induced autophagy was up-regulated by the Ambra1 overexpression or was down-regulated by the Ambra1 knockdown. In addition, the colony forming was also positively regulated by Ambra1 in DU145 cells post cisplatin treatment. In conclusion, Ambra1 negatively regulates the cisplatin-induced apoptosis and the cisplatin-mediated growth reduction in DU145 cells, in association with the Ambra1-mediated autophagy promotion. It implies that Ambra1-mediated autophagy might be an important mechanism underlining the sensitivity reduction of PCa cells.

Novel Thienopyrimidine Derivative, RP-010, Induces β-Catenin Fragmentation and Is Efficacious against Prostate Cancer Cells

Thienopyrimidines containing a thiophene ring fused to pyrimidine are reported to have a wide-spectrum of anticancer efficacy in vitro. Here, we report for the first time that thieno[3,2-d]pyrimidine-based compounds, also known as the RP series, have efficacy in prostate cancer cells. The compound RP-010 was efficacious against both PC-3 and DU145 prostate cancer (PC) cells (IC₅₀ < 1 µM). The cytotoxicity of RP-010 was significantly lower in non-PC, CHO, and CRL-1459 cell lines. RP-010 (0.5, 1, 2, and 4 µM) arrested prostate cancer cells in G2 phase of the cell cycle, and induced mitotic catastrophe and apoptosis in both PC cell lines. Mechanistic studies suggested that RP-010 (1 and 2 µM) affected the wingless-type MMTV (Wnt)/β-catenin signaling pathway, in association with β-catenin fragmentation, while also downregulating important proteins in the pathway, including LRP-6, DVL3, and c-Myc. Interestingly, RP-010 (1 and 2 µM) induced nuclear translocation of the negative feedback proteins, Naked 1 and Naked 2, in the Wnt pathway. In addition, RP-010 (0.5, 1, 2 and 4 µM) significantly decreased the migration of PC cells in vitro. Finally, RP-010 did not produce significant toxic effects in zebrafish at concentrations of up to 6 µM. In conclusion, RP-010 may be an efficacious and relatively nontoxic anticancer compound for prostate cancer. Future mechanistic and in vivo efficacy studies are needed to optimize the hit compound RP-010 for lead optimization and clinical use.

Dihydrotestosterone inhibits arylsulfatase B and Dickkopf Wnt signaling pathway inhibitor (DKK)-3 leading to enhanced Wnt signaling in prostate epithelium in response to stromal Wnt3A

BACKGROUND

In tissue microarrays, immunostaining of the enzyme arylsulfatase B (ARSB; N-acetylgalactosamine-4-sulfatase) was less in recurrent prostate cancers and in cancers with higher Gleason scores. In cultured prostate stem cells, decline in ARSB increased Wnt signaling through effects on Dickkopf Wnt Signaling Pathway Inhibitor (DKK)3. The effects of androgen exposure on ARSB and the impact of decline in ARSB on Wnt signaling in prostate tissue were unknown.

METHODS

Epithelial and stromal tissues from malignant and normal human prostate were obtained by laser capture microdissection. mRNA expression of ARSB, galactose-6-sulfate-sulfatase (GALNS) and Wnt-signaling targets was determined by QPCR. Non-malignant human epithelial and stromal prostate cells were grown in tissue culture, including two-cell layer cultures. ARSB was silenced by specific siRNA, and epithelial cells were treated with stromal spent media following treatment with IWP-2, an inhibitor of Wnt secretion, and by exogenous recombinant human Wnt3A. Promoter methylation was detected using specific DKK3 and ARSB promoter primers. The effects of DHT and of ARSB overexpression on DKK expression were determined. Cell proliferation was assessed by BrdU incorporation.

RESULTS

Normal stroma showed higher expression of vimentin, ARSB, and Wnt3A than epithelium. Normal epithelium had higher expression of E-cadherin, galactose 6-sulfate-sulfatase (GALNS), and DKK3 than stroma. In malignant epithelium, expression of ARSB and DKK3 declined, and expression of GALNS and Wnt signaling targets increased. In cultured prostate epithelial cells, Wnt-mediated signaling was greatest when ARSB was silenced and cells were exposed to exogenous Wnt3A. Exposure to 5α-dihydrotestosterone (DHT) increased ARSB and DKK3 promoter rmethylation, and effects of DHT on DKK3 expression were reversed when ARSB was overexpressed.

CONCLUSIONS

Androgen-induced declines in ARSB and DKK3 may contribute to prostate carcinogenesis by sustained activation of Wnt signaling in prostate epithelium in response to stromal Wnt3A.

Halogen-substituted anthranilic acid derivatives provide a novel chemical platform for androgen receptor antagonists

Androgen receptor (AR) antagonists are used for hormone therapy of prostate cancer (PCa). However resistance to the treatment occurs eventually. One possible reason is the occurrence of AR mutations that prevent inhibition of AR-mediated transactivation by antagonists. To offer in future more options to inhibit AR signaling, novel chemical lead structures for new AR antagonists would be beneficial. Here we analyzed structure-activity relationships of a battery of 36 non-steroidal structural variants of methyl anthranilate including 23 synthesized compounds. We identified structural requirements that lead to more potent AR antagonists. Specific compounds inhibit the transactivation of wild-type AR as well as AR mutants that render treatment resistance to hydroxyflutamide, bicalutamide and the second-generation AR antagonist enzalutamide. This suggests a distinct mode of inhibiting the AR compared to the clinically used compounds. Competition assays suggest binding of these compounds to the AR ligand binding domain and inhibit PCa cell proliferation. Moreover, active compounds induce cellular senescence despite inhibition of AR-mediated transactivation indicating a transactivation-independent AR-pathway. In line with this, fluorescence resonance after photobleaching (FRAP) - assays reveal higher mobility of the AR in the cell nuclei. Mechanistically, fluorescence resonance energy transfer (FRET) - assays indicate that the amino-carboxy (N/C)-interaction of the AR is not affected, which is in contrast to known AR-antagonists. This suggests a mechanistically novel mode of AR-antagonism. Together, these findings indicate the identification of a novel chemical platform as a new lead structure that extends the diversity of known AR antagonists and possesses a distinct mode of antagonizing AR-function.

Knockdown of FOXP1 promotes the development of lung adenocarcinoma

Lung cancer is one of the most common cancers in the world, which accounts for about 27% of all cancer deaths. However, the mechanisms underlying the pathogenesis of lung cancer cells remain largely elusive. In this study, we examined the role of the Forkhead box protein P1 (FOXP1) in lung cancer development. Our Oncomine analysis shows that FOXP1 is downregulated in lung adenocarcinoma compared with normal lung tissue. Knockdown of FOXP1 promotes the growth and invasion of PC9 and A549 cells by regulating genes of chemokine signaling molecules, including CCR1, ADCY5, GNG7, VAV3, and PLCB1. Simultaneous knockdown of CCR1 and FOXP1 attenuated FOXP1 knockdown-induced increase of lung cancer cell growth. Finally, knockdown of FOXP1 in PC9 cells promotes the tumorigenesis via CCR1 signaling in xenograft mouse model. Taken together, our data suggest that FOXP1 plays important roles in preventing lung adenocarcinoma development via suppressing chemokine signaling pathways.

Identification of the Transcription Factor Relationships Associated with Androgen Deprivation Therapy Response and Metastatic Progression in Prostate Cancer

Background: Patients with locally advanced or recurrent prostate cancer typically undergo androgen deprivation therapy (ADT), but the benefits are often short-lived and the responses variable. ADT failure results in castration-resistant prostate cancer (CRPC), which inevitably leads to metastasis. We hypothesized that differences in tumor transcriptional programs may reflect differential responses to ADT and subsequent metastasis. Results: We performed whole transcriptome analysis of 20 patient-matched Pre-ADT biopsies and 20 Post-ADT prostatectomy specimens, and identified two subgroups of patients (high impact and low impact groups) that exhibited distinct transcriptional changes in response to ADT. We found that all patients lost the AR-dependent subtype (PCS2) transcriptional signatures. The high impact group maintained the more aggressive subtype (PCS1) signal, while the low impact group more resembled an AR-suppressed (PCS3) subtype. Computational analyses identified transcription factor coordinated groups (TFCGs) enriched in the high impact group network. Leveraging a large public dataset of over 800 metastatic and primary samples, we identified 33 TFCGs in common between the high impact group and metastatic lesions, including SOX4/FOXA2/GATA4, and a TFCG containing JUN, JUNB, JUND, FOS, FOSB, and FOSL1. The majority of metastatic TFCGs were subsets of larger TFCGs in the high impact group network, suggesting a refinement of critical TFCGs in prostate cancer progression. Conclusions: We have identified TFCGs associated with pronounced initial transcriptional response to ADT, aggressive signatures, and metastasis. Our findings suggest multiple new hypotheses that could lead to novel combination therapies to prevent the development of CRPC following ADT.

Recent trends in the management of advanced prostate cancer

Advanced prostate cancer includes a wide spectrum of disease ranging from hormone naïve or hormone sensitive to castration resistant, both containing populations of men who have demonstrable metastatic and non-metastatic states. The mainstay of treatment for metastatic hormone-sensitive prostate cancer is androgen deprivation therapy (ADT). However, recent level 1 evidence demonstrates that the addition of chemotherapy or abiraterone acetate to ADT results in significant survival advantage as compared with ADT alone. Furthermore, in non-metastatic castration-resistant prostate cancer (M0 CRPC), two second-generation anti-androgens, apalutamide and enzalutamide, when used in combination with ADT, have demonstrated a significant benefit in metastasis-free survival. Here, we review the most recent studies leading to these significant changes in the treatment of advanced prostate cancer.

Nur77 suppression facilitates androgen deprivation-induced cell invasion of prostate cancer cells mediated by TGF-β signaling

BACKGROUND

Androgen deprivation therapy (ADT) remains a standard treatment for advanced prostate cancers. However, recent studies revealed that while inhibiting the growth of certain types of prostate cancer cells, ADT promotes invasion. In the current study, we explored the effects of Nur77, an orphan nuclear receptor, on prostate cancer cell invasion following ADT.

METHODS

Androgen receptor (AR) and Nur77 protein expression in patient tissues and cell lines were quantified via ELISA and western blot. The effects of AR-signaling on Nur77 expression were examined. The effects of Nur77 over-expression and knockdown on ADT-induced prostate cancer cell invasion were characterized.

RESULTS

The results showed that AR and Nur77 are both highly expressed in prostate cancers of patients. Nur77 is positively regulated by AR-signaling at transcriptional level in NCI-H660, a widely used prostate cancer cell line. AR antagonists, Casodex and MDV3100 treatment resulted in significant inhibition of prostate cancer cell growth but enhanced cancer cell invasion. Nur77 over-expression blocked invasion-promoting effect of ADT, which is consistent with the down-regulation of MMP9 and Snail protein expression. Further mechanistic investigations showed that Nur77 inhibited transcription of TGF-β target genes (Snail and MMP9), and thereby inhibits TGF-β-mediated prostate cancer cell invasion following androgen antagonism. In addition, our data suggested the nature of this inhibitory effect of Nur77 on TGF-β-signaling is selective, for Smad3-signaling, the classical effector of TGF-β-signaling, was not interrupted by Nur77 over-expression.

CONCLUSION

Considering the limited success of management of prostate cancer metastasis following ADT, our data strongly suggest that Nur77 regulation could be a promising direction for search of complementary therapeutic strategy on top of classic ADT therapy.