Called Castration-resistant Prostate Cancer Research Articles

THE ROLE OF DOCETAXEL AS FIRST-LINE CHEMOTHERAPY ON PSA LEVEL AND QOL IN CRPC PATIENTS

Objective: Prostate cancer is the second most common cancer in men and the fifth leading cause of death worldwide. 10-20% of cases can progress to a more aggressive stage called castration-resistant prostate cancer (CRPC) with a higher death rate. Clinical guidelines recommend docetaxel as first-line chemotherapy and evaluated using the PSA test. This study aims to investigate the effect of docetaxel chemotherapy on PSA levels in CRPC. Material & Methods: A retrospective study was conducted from January 2016 until August 2022 according to the medical records database Saiful Anwar Hospital. There were 16 patients who met the inclusion criteria, including male patients with a diagnosis of CRPC who received castration therapy and found an increase in PSA 3 times of nadir or found 2 or more bone metastatic lesions or soft tissue lesions > 2 cm, received 6 series of docetaxel chemotherapy, and have a PSA data was performed before and after chemotherapy. Statistical analysis was performed using a differential T-test. Results: The results, obtained were significantly different (p<0.05) on the average PSA (log) pre-post chemotherapy, visual analog scale (VAS), and quality of life, and not significantly different on BMI pre-post chemotherapy. Conclusion: 6 cycles of docetaxel chemotherapy resulted in a decrease in PSA levels of CRPC significantly. It showed an excellent response to docetaxel chemotherapy in managing CRPC patients. Limitations of this study were specifically the retrospective cohort study model and the ability to reduce PSA levels in assessing the prognosis of CRPC. Keywords: Castration-resistant prostate cancer, chemotherapy, docetaxel, prostate-specific antigen.

Identification of DNA damage response-related genes as biomarkers for castration-resistant prostate cancer

Although hormone therapy is effective for the treatment of prostate cancer (Pca), many patients develop a lethal type of Pca called castration-resistant prostate cancer (CRPC). Dysregulation of DNA damage response (DDR)-related genes leads to Pca progression. Here, we explored DDR-related signals upregulated in CRPC tissues. We analyzed the gene expression profiles in our RNA-sequence (RNA-seq) dataset containing benign prostate, primary Pca, and CRPC samples. We identified six DDR-related genes (Ribonuclease H2 Subunit A (RNASEH2A), replication factor C subunit 2 (RFC2), RFC4, DNA Ligase 1 (LIG1), DNA polymerase D1 (POLD1), and DNA polymerase E4 (POLE4)) that were upregulated in CRPC compared with Pca tissues. By analyzing public databases and validation studies, we focused on RFC2 as a new biomarker. Functional analysis demonstrated that silencing of RFC2 expression inhibited cell proliferation and induced the expression of DNA damage and apoptosis markers in CRPC model cells. Furthermore, immunohistochemical (IHC) analysis revealed that high expression of RFC2 protein correlated with poor prognosis in patients with Pca and increased expression in CRPC tissues compared with localized Pca. Thus, our study suggests that six DDR-related genes would be important for Pca progression. RFC2 could be a useful biomarker associated with poor outcomes of patients with Pca.

Extreme bipolar androgen therapy with darolutamide and testosterone cypionate in patients with metastatic castration-resistant prostate cancer: ExBAT (LACOG 0620) trial.

TPS276 Background: Prostate cancer has an intrinsic dependence on androgens and androgen receptor (AR) regulation. Suppression of gonadal androgen synthesis known as androgen deprivation therapy (ADT), either by orchiectomy or by pharmacological modulation, represents the treatment backbone of metastatic disease. Unfortunately, almost invariably, patients develop resistance to ADT, progressing to a state called castration-resistant prostate cancer (CRPC), defined as disease progression at serum testosterone levels in the castrate range. Bipolar Androgen Therapy (BAT), consisting of exogenous supraphysiological doses of testosterone followed by castrate levels, has shown clinical activity in multiple early phase clinical trials, in addition to improvement of quality of life (QoL) in CRPC patients. Alternated administration of BAT and novel AR-targeted therapies, a strategy entitled by our group as Extreme Bipolar Androgen Therapy (ExBAT), has never been tested in patients with CRPC. The objective of our study is to assess the ExBAT approach in metastatic CRPC. Methods: ExBAT (NCT04558866) is a phase 2, single-arm, multicenter trial assessing patients with mCRPC who progressed to abiraterone by PCWG3 criteria. Prior docetaxel for metastatic hormone-sensitive disease is allowed if ≥ 12 months elapsed from last dose of docetaxel. Included patients receive testosterone cypionate 400 mg IM on day 1 followed by darolutamide 1,200 mg/day orally for 4 weeks (starting on day 29 through day 56) on 63-day cycles. The primary endpoint is radiographic progression-free survival (rPFS) at 12 months. Secondary endpoints include PSA decline rates, overall survival, toxicity, quality of life, and predictive biomarkers of response/survival. Tumor assessments are performed every 9 weeks, for the first 2 cycles and every 18 weeks thereafter up to 12 months. Patients with disease progression with clinical benefit are allowed to continue treatment. Patients without disease progression after 12 months are allowed to receive study treatment on Extension Phase. The sample size of 47 patients (considering 5% drop-out) was calculated based on the primary endpoint using a two-sided 5% significance level Chi-square Test for One Proportion and achieves 80% power to detect the difference between a 50% rPFS at 12 months comparing with 30% in the historic control group. NCT04558866. From June2021 to September2022, 31 of planned 47 patients have been enrolled in 8 Brazilian centers. Results are not available at the time of submission. Clinical trial information: NCT04558866 .

Androgen-Independent Prostate Cancer Is Sensitive to CDC42-PAK7 Kinase Inhibition.

Prostate cancer is a common form of cancer in men, and androgen-deprivation therapy (ADT) is often used as a first-line treatment. However, some patients develop resistance to ADT, and their disease is called castration-resistant prostate cancer (CRPC). Identifying potential therapeutic targets for this aggressive subtype of prostate cancer is crucial. In this study, we show that statins can selectively inhibit the growth of these CRPC tumors that have lost their androgen receptor (AR) and have overexpressed the RNA-binding protein QKI. We found that the repression of microRNA-200 by QKI overexpression promotes the rise of AR-low mesenchymal-like CRPC cells. Using in silico drug/gene perturbation combined screening, we discovered that QKI-overexpressing cancer cells are selectively vulnerable to CDC42-PAK7 inhibition by statins. We also confirmed that PAK7 overexpression is present in prostate cancer that coexists with hyperlipidemia. Our results demonstrate a previously unseen mechanism of action for statins in these QKI-expressing AR-lost CRPCs. This may explain the clinical benefits of the drug and support the development of a biology-driven drug-repurposing clinical trial. This is an important finding that could help improve treatment options for patients with this aggressive form of prostate cancer.

1-Benzyloxy-5-phenyltetrazole derivatives highly active against androgen receptor-dependent prostate cancer cells

A series of 1-benzyloxy-5-phenyltetrazole derivatives and similar compounds were synthesized and evaluated for their in vitro inhibitory activity against androgen-receptor-dependent (22Rv1) and androgen-receptor independent (PC3) prostate cancer cells. The most active compounds had in vitro IC50 values against 22Rv1 cells of <50 nM and showed apparent selectivity for this cell type over PC3 cells; however, these active compounds had short half-lives when incubated with mouse liver microsomes and/or when plasma concentration was monitored during in vivo pharmacokinetic studies in mice or rats. Importantly, lead compound 1 exhibited promising inhibitory effects on cell proliferation, expression of AR and its splicing variant AR-v7 as well as AR regulated target genes in 22Rv1 cells, which are so called castration-resistant prostate cancer (CRPC) cells, and a 22Rv1 CRPC xenograft tumour model in mice. Structural changes which omitted the N–O-benzyl moiety led to dramatic or total loss of activity and S-benzylation of a cysteine derivative, as a surrogate for in vivo S-nucleophiles, by representative highly active compounds, suggested a possible chemical reactivity basis for this “activity cliff” and poor pharmacokinetic profile. However, representative highly active compounds did not inhibit a cysteine protease, indicating that the mode of activity is unlikely to be protein modification by S-benzylation. Despite our efforts to elucidate the mode of action, the mechanism remains unclear.

Abstract A021: Lysine methylation in EHMT1/GLP acts as a molecular switch to reprogram transcription networks to drive prostate cancer progression

Abstract Background: Prostate Cancer (PCa) progresses to a metastatic form of cancer called Castration-Resistant Prostate Cancer (CRPC) after treatment with androgen deprivation therapies (ADTs). Epigenetic reprogramming through altered expression and activity of histone modifier proteins is one major mechanism of tumor resistance. In particular, histone lysine methyltransferases (KMTs) and demethylases (KDMs) are important epigenetic targets in CRPC. In this study, we have focused on studying the function and regulation of Euchromatic Histone Methyltransferase 1 protein (EHMT1/GLP), which is a well-known H3K9 methyltransferase and functions in repressing gene transcription. EHMT family genes are altered in ~2-3% of primary PCa and ~10% of CRPC (primarily gene amplification) and their expression levels are significantly increased in CRPC, suggesting these proteins may have oncogenic activities in driving CRPC progression. Methods: We conducted an integrated analysis of ChIP-seq and RNA-seq analysis in LNCaP PCa cells to characterize the transcription program of EHMT1. We then performed proteomics analyses in VCaP and LNCaP PCa cells to identify post-translational modifications of EHMT1 and functionally validated the findings by generating loss-of-function mutations. We performed a histone demethylase assay to discover if EHMT1 is a substrate of LSD1 (a member of the KDM family). Moreover, we also assessed the effects of EHMT1 silencing or inhibition (in multiple PCa cell lines) on cell proliferation and metastasis in vitro using cell cycle analysis and transwell migration assay, and tumor growth and metastasis in vivo using mouse subcutaneous injection and zebrafish embryo injection approaches. Results: Our data showed that EHMT1 can transcriptionally activate multiple oncogenic pathways, including E2F and MYC signaling. Proteomic analyses revealed that EHMT1 is methylated in PCa cell lines, with dual-lysine methylation occurring at the K450/K451 sites. The histone demethylase assay showed that methylated K450, but not K451 is a potential substrate of LSD1. By generating the K450R, K451R, and K450/451R mutants, we showed that the K450/451R mutant, but not any single lysine mutants, can greatly expand EHMT1 chromatin binding independent of its H3K9 methyltransferase activity. This mutant also significantly induced EHMT1 oncogenic activity by activating E2F and MYC pathways. Moreover, EHMT1 silencing, or inhibition can significantly suppress tumor growth and metastasis. Conclusion: We have demonstrated that EHMT1 can function to activate oncogenic transcriptional programs in PCa by an H3K9-independent mechanism, possibly mediated through dual-lysine demethylation at K450/451 sites. Our data also suggest that targeting EHMT1 in CRPC may be a potential therapeutic strategy to suppress tumor growth and metastasis. Citation Format: Anna Besschetnova, Wanting Han, Mingyu Liu, Yanfei Gao, Muqing Li, Zifeng Wang, Maryam Labaf, Susan Patalano, Kavita Venkataramani, Rachel Muriph, Jill Macoska, Kellee Siegfried-Harris, Jason Evans, Steven Balk, Shuai Gao, Dong Han, Changmeng Cai. Lysine methylation in EHMT1/GLP acts as a molecular switch to reprogram transcription networks to drive prostate cancer progression. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Epigenomics; 2022 Oct 6-8; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2022;82(23 Suppl_2):Abstract nr A021.

Dual-Acting Peptides Target EZH2 and AR: A New Paradigm for Effective Treatment of Castration-Resistant Prostate Cancer.

Prostate cancer starts as a treatable hormone-dependent disease, but often ends in a drug-resistant form called castration-resistant prostate cancer (CRPC). Despite the development of the antiandrogens enzalutamide and abiraterone for CRPC, which target the androgen receptor (AR), drug resistance usually develops within 6 months and metastatic CRPC (mCRPC) leads to lethality. EZH2, found with SUZ12, EED, and RbAP48 in Polycomb repressive complex 2 (PRC2), has emerged as an alternative target for the treatment of deadly mCRPC. Unfortunately, drugs targeting EZH2 have shown limited efficacy in mCRPC. To address these failures, we have developed novel, dual-acting peptide inhibitors of PRC2 that uniquely target the SUZ12 protein component, resulting in the inhibition of both PRC2 canonical and noncanonical functions in prostate cancer. These peptides were found to inhibit not only the EZH2 methylation activity, but also block its positive effect on AR gene expression in prostate cancer cells. Since the peptide effect on AR levels is transcriptional, the inhibitory peptides can block the expression of both full-length AR and its splicing variants including AR-V7, which plays a significant role in the development of drug resistance. This dual-mode action provides the peptides with the capability to kill enzalutamide-resistant CRPC cells. These peptides are also more cytotoxic to prostate cancer cells than the combination of enzalutamide and an EZH2 inhibitory drug, which was recently suggested to be an effective treatment of mCRPC disease. Our data show that such a dual-acting therapeutic approach can be more effective than the existing front-line drug therapies for treating deadly mCRPC.

Exploring anti-androgen therapies in hormone dependent prostate cancer and new therapeutic routes for castration resistant prostate cancer.

Androgen deprivation therapies (ADTs) are important treatments which inhibit androgen-induced prostate cancer (PCa) progression by either preventing androgen biosynthesis (e.g. abiraterone) or by antagonizing androgen receptor (AR) function (e.g. bicalutamide, enzalutamide, darolutamide). A major limitation of current ADTs is they often remain effective for limited durations after which patients commonly progress to a lethal and incurable form of PCa, called castration-resistant prostate cancer (CRPC) where the AR continues to orchestrate pro-oncogenic signalling. Indeed, the increasing numbers of ADT-related treatment-emergent neuroendocrine-like prostate cancers (NePC), which lack AR and are thus insensitive to ADT, represents a major therapeutic challenge. There is therefore an urgent need to better understand the mechanisms of AR action in hormone dependent disease and the progression to CRPC, to enable the development of new approaches to prevent, reverse or delay ADT-resistance. Interestingly the AR regulates distinct transcriptional networks in hormone dependent and CRPC, and this appears to be related to the aberrant function of key AR-epigenetic coregulator enzymes including the lysine demethylase 1 (LSD1/KDM1A). In this review we summarize the current best status of anti-androgen clinical trials, the potential for novel combination therapies and we explore recent advances in the development of novel epigenetic targeted therapies that may be relevant to prevent or reverse disease progression in patients with advanced CRPC.

Abstract LB035: Understanding the mechanism of neuropilin2 upregulation in advanced prostate cancer

Abstract Background: Prostate cancer management involves administering Androgen Deprivation Therapy (ADT). Patients with advanced form of the disease become resistant to ADT and progress to a lethal phenotype called Castration Resistant Prostate Cancer (CRPC). Neuropilin-2 is upregulated in advanced prostate cancer. It has been implicated in decreasing the overall survival of such patients by inducing therapy-resistance. Significance: Understanding how NRP2 is differentially expressed will uncover molecular pathways that can be targeted to develop a specific treatment strategy for better management of patients. Experimental Design: We checked NRP2 expression in different prostate cancer cell lines {LNCaP, C4-2 and C4-2 P53/RB1 null cells (DKD cells)} and the level of methylation of the NRP2 promoter in these cells by pyrosequencing. We demethylated the NRP2 promoter by treatment with 5’Azacytidine and checked NRP2 mRNA expression. We analyzed the NRP2 promoter activity under demethylated conditions by transfecting cells with a demethylated NRP2 promoter construct using a GLuc dual-luciferase assay. Using Biobase we found DNA sequences for binding of transcription factors within the NRP2 promoter. RNA-Seq, RT-PCR was performed to identify potential transcription factors of NRP2(highly expressed in DKD cells). To validate SOX2 as a transcription factor for NRP2, we tested its binding to NRP2 promoter by ChIP-q-PCR. Requirement of SOX2 in transcribing NRP2 mRNA in C4-2 and DKD cells was tested by both knocking down or ectopically expressing SOX2. To determine whether demethylation of NRP2 promoter is a prerequisite for SOX2 binding, SOX2 was overexpressed in LNCaP cells following 5’Azacytidine and monitored the change in the NRP2 expression. Results: NRP2 expression was low in LNCaP cells. It steadily increased in C4-2 cells with a steep rise in the DKD cells. Pyrosequencing showed a high level of DNA methylation in LNCaP cells compared to C4-2 cells. On treatment with 5’Azacytidine, NRP2 mRNA expression was upregulated in the LNCaP cells and it significantly rose in the C4-2 cells. Our dual-luciferase assay showed us that in C4-2 cells, the promoter activity of NRP2 upon demethylation went up causing a significant rise in Luciferase expression. RNA-seq and RT-PCR analysis showed high SOX2 levels in DKD cells indicating that SOX2 might play a role in elevating NRP2 expression in these cells. ChIP q-PCR indicated enriched binding of SOX2 in the NRP2 promoter in DKD cells. On silencing SOX2 in DKD cells, the expression of NRP2 was decreased. Analogous to this finding, overexpressing SOX2 in C4-2 cells caused significant rise in NRP2 expression, whereas in LNCaP cells, there was no change. Demethylation of NRP2 promoter and simultaneous overexpression of SOX2 in LNCaP lead to a significant increase in NRP2 mRNA suggesting the requirement of demethylated NRP2 promoter for SOX2 function. Conclusion: The differential expression of NRP2 in advanced prostate cancer is a two-step process of initial demethylation of the DNA in the NRP2 promoter region, followed by binding of SOX2 Citation Format: Sanika Bodas, Ridwan Islam, Sreyashi Bhattacharya, Juhi Mishra, Dipanwita Das, Michael Muders, Samikshan Dutta, Benjamin A. Teply, Kaustubh Datta. Understanding the mechanism of neuropilin2 upregulation in advanced prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB035.

Anti-Androgen Receptor Therapies in Prostate Cancer: A Brief Update and Perspective.

Prostate cancer is a major health issue in western countries and is the second leading cause of cancer death in American men. Prostate cancer depends on the androgen receptor (AR), a transcriptional factor critical for prostate cancer growth and progression. Castration by surgery or medical treatment reduces androgen levels, resulting in prostatic atrophy and prostate cancer regression. Thus, metastatic prostate cancers are initially managed with androgen deprivation therapy. Unfortunately, prostate cancers rapidly relapse after castration therapy and progress to a disease stage called castration-resistant prostate cancer (CRPC). Currently, clinical treatment for CRPCs is focused on suppressing AR activity with antagonists like Enzalutamide or by reducing androgen production with Abiraterone. In clinical practice, these treatments fail to yield a curative benefit in CRPC patients in part due to AR gene mutations or splicing variations, resulting in AR reactivation. It is conceivable that eliminating the AR protein in prostate cancer cells is a promising solution to provide a potential curative outcome. Multiple strategies have emerged, and several potent agents that reduce AR protein levels were reported to eliminate xenograft tumor growth in preclinical models via distinct mechanisms, including proteasome-mediated degradation, heat-shock protein inhibition, AR splicing suppression, blockage of AR nuclear localization, AR N-terminal suppression. A few small chemical compounds are undergoing clinical trials combined with existing AR antagonists. AR protein elimination by enhanced protein or mRNA degradation is a realistic solution for avoiding AR reactivation during androgen deprivation therapy in prostate cancers.

Enhanced antitumor efficacy by combining afatinib with MDV3100 in castration-resistant prostate cancer.

Background: Patients with prostate cancer often develop resistance to androgen deprivation therapy, a condition called castration-resistant prostate cancer (CRPC). Enzalutamide (MDV3100) can prolong the survival of patients with CRPC after chemotherapy, but ∼50% of patients eventually relapse and develop resistance to MDV3100. Thus, it is necessary to explore new treatment methods to improve the therapeutic effect of MDV3100. Tyrosine kinases play an essential role in the pathogenesis of CRPC. Methods: MTT assay was used to detect the inhibitory effects of MDV3100 and tyrosine kinase inhibitor on prostate cancer cells. CompuSyn version 1.0 was used to calculate the combination index (CI) values using the Chou-Talalay method. Clone formation and EdU assay were used to detect the effect of afatinib combined with MDV3100 on the proliferation of 22Rv1 cells. RT-qPCR and Western blot were used to explore the mechanism of drug combination. The aim of the present study was to determine the effects of several tyrosine kinase inhibitors (TKIs) when used in combination with MDV3100 in vitro. Results: The results demonstrated that TKIs combined with MDV3100 exerted a synergistic effect on a variety of PCa cells. Afatinib combined with MDV3100 could suppress the proliferation and migration of 22RV1 cells, as well as cause their cell cycle arrest and apoptosis. Mechanistically, afatinib effectively reduced the protein expression levels of HER2 and HER3 and inhibited EGFR phosphorylation, thereby enhancing the effect of MDV3100 and suppressing CRPC. Conclusions: These findings suggested that afatinib treatment improved the effect of MDV3100 on 22RV1 cells, highlighting this drug as a potential therapeutic strategy for patients with CRPC.

Inhibition of noncanonical Wnt pathway overcomes enzalutamide resistance in castration-resistant prostate cancer.

Because androgen receptor (AR) signaling is essential for prostate cancer (PCa) initiation and progression, castration is the main approach for treatment. Unfortunately, patients tend to enter a stage called castration-resistant prostate cancer (CRPC) despite the initial response to castration. For various reasons, AR signaling is reactivated in CRPC. As such, AR signaling inhibitors, such as enzalutamide, has been approved by the Food and Drug Administration to treat CRPC in the clinic. However, the limited success of these new drugs suggests an immediate unmet need to understand the underlying mechanisms for resistance so novel targets can be identified to enhance their efficacy. An unbiased bioinformatics analysis was performed with the existing human patient dataset and RNA-seq results of in-house PCa cell lines to identify new targets to overcome enzalutamide resistance. Cell viability and growth were detected by 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide and colony formation assay. Cell invasion and migration were detected by transwell assay. Protein levels were detected by Western blot or immunofluorescence. We found that the noncanonical Wnt signaling was activated in enzalutamide-resistant PCa cells and that the activation of noncanonical Wnt signaling was correlated with AR expression and disease progression. This was validated by the elevated expression of noncanonical Wnt pathway members such as Wnt5a, RhoA, and ROCK in enzalutamide-resistant PCa cells in comparison to their enzalutamide-sensitive counterparts. And, both Y27632, an inhibitor of ROCK, and depletion of ROCK enhanced the efficacy of enzalutamide in enzalutamide-resistant PCa cells. Of significance, a combination of Y27632 and enzalutamide inhibited 22RV1-derived xenograft tumor growth synergistically. Finally, ROCK depletion plus enzalutamide treatment inhibited invasion and migration of enzalutamide-resistant PCa cells via inhibition of epithelial-mesenchymal transition. The noncanonical Wnt pathway is activated in enzalutamide-resistant PCa and inhibition of noncanonical Wnt pathway overcomes enzalutamide resistance and enhances its efficacy in CRPC.

CPT1A Supports Castration-Resistant Prostate Cancer in Androgen-Deprived Conditions.

Prostate cancer (PCa) is the most common cancer in men, and the global burden of the disease is rising. The majority of PCa deaths are due to metastasis that are highly resistant to current hormonal treatments; this state is called castration-resistant prostate cancer (CRPC). In this study, we focused on the role of the lipid catabolism enzyme CPT1A in supporting CRPC growth in an androgen-dependent manner. We found that androgen withdrawal promoted the growth of CPT1A over-expressing (OE) tumors while it decreased the growth of CPT1A under-expressing (KD) tumors, increasing their sensitivity to enzalutamide. Mechanistically, we found that CPT1A-OE cells burned more lipid and showed increased histone acetylation changes that were partially reversed with a p300 specific inhibitor. Conversely, CPT1A-KD cells showed less histone acetylation when grown in androgen-deprived conditions. Our results suggest that CPT1A supports CRPC by supplying acetyl groups for histone acetylation, promoting growth and antiandrogen resistance.

Cyclohexanone curcumin analogs inhibit the progression of castration-resistant prostate cancer invitro and invivo.

Many prostate cancer patients develop resistance to treatment called castration‐resistant prostate cancer (CRPC) which is the major cause of recurrence and death. In the present study, four cyclohexanone curcumin analogs were synthesized. Additionally, their anticancer progression activity on CRPC cell lines, PC3 and PLS10 cells, was examined. We first determined their anti‐metastasis properties and found that 2,6‐bis‐(4‐hydroxy‐3‐methoxy‐benzylidene)‐cyclohexanone (2A) and 2,6‐bis‐(3,4‐dihydroxy‐benzylidene)‐cyclohexanone (2F) showed higher anti‐invasion properties against CRPC cells than curcumin. Analog 2A inhibited both MMP‐2 and MMP‐9 secretions and activities, whereas analog 2F reduced only MMP activities. These findings suggest that the compounds may inhibit CRPC cell metastasis by decreased extracellular matrix degradation. Analog 2A, the most potent analog, was then subjected to an in vivo study. Similar to curcumin, analog 2A was detectable in the serum of mice at 30 and 60 minutes after i.p. injections. Analog 2A and curcumin (30 mg/kg bodyweight) showed a similar ability to reduce tumor area in lungs of mice that were i.v. injected with PLS10 cells. Additionally, analog 2A showed superior growth inhibitory effect on PLS10 cells than that of curcumin both in vitro and in vivo. The compound inhibited PLS10 cells growth by induction of G1 phase arrest and apoptosis in vitro. Interestingly, analog 2A significantly decreased tumor growth with downregulation of cell proliferation and angiogenesis in PLS10‐bearing mice. Taken together, we could summarize that analog 2A showed promising activities in inhibiting CRPC progression both in vitro and in vivo.

Epigenetic Regulation by Androgen Receptor in Prostate Cancer

Prostate cancer is the most commonly diagnosed cancer in men all over the world. Androgen receptor (AR) functions as a nuclear receptor to facilitate ligand-dependent transcriptional activation in the nucleus. Advanced prostate cancer is treated with androgen deprivation therapy (ADT) because androgen and AR signaling drive the prostate tumor growth and anti-apoptotic ability. Resistance to ADT in most tumors develops quickly, but AR continues to be active in relapsed tumors called castration-resistant prostate cancer (CRPC). Therefore, it is important to understand AR transcriptional mechanism and downstream signaling. Recent studies have shown the central role of chromatin structure and histone modifications in AR-mediated gene regulation. Furthermore, AR functions through interaction with several tissue-specific transcription factors such as forkhead box protein A1 (FOXA1). Interestingly, non-coding RNAs such as long non-coding RNAs (lncRNAs) and micro RNAs (miRNAs) modulate epigenetic status to promote AR function directly or indirectly and have central roles in prostate cancer progressions. The focus of this review is on the involvement of AR in epigenetic regulation in prostate cancer development and progression.

Abstract B56: Regulation of CXCR5-CXCL13 signaling in prostate cancer etiologic disparities

Abstract The prevalence of prostate cancer (PCa) has been a worldwide burden. Cancer of the prostate is the most prevalent form of cancer in men and the second leading cause of death due to cancer in men in the United States and Europe. There is a major health disparity associated with PCa; the number of fatalities associated with this disease is more significant in African-American (AA) men than in European American (EA) men. Disease progression occurs despite hormone ablation therapy, which leads to a condition called castration-resistant prostate cancer (CRPC). Further complicating the matter, CRPC is a disease that affects a variety of patients differently, which can be problematic for physicians to provide standardized treatments with similar outcomes. AAs with CRPC can experience significantly lower rates of overall survival, faster rates of tumor progression, and poor responses to chemotherapy compared to EAs with this disease. We previously showed that CXCL13:CXCR5 axis plays a role in PCa pathobiology and is also associated with PCa aggressiveness; CXCR5 signaling mediates PCa cell growth, migration, invasion, and docetaxel resistance. To further understand the implication of CXCR5-CXCL13 in CRPC, we characterize the reason behind the health disparities seen across groups of PCa patients by evaluating the difference in regulatory molecules (miRNAs) on CXCL13-CXCR5 signaling. We found the expression profile of CXCL13 and CXCR5 RNA to be associated with miRNAs (miR-140-3p.1, miR-24-3p, miR-200c, miR-221-3p/22-3p, miR-192-5p/215-5p, miR-214-5p). Using RNA-seq datasets from the Gene Expression Omnibus (GEO) and the Sequence Read Archive (SRA), CXCL13 and CXCR5 RNA as well as associated miRNAs (miR-140-3p.1, miR-24-3p, miR-221-3p/22-3p, miR-192-5p/215-5p, and miR-214-5p) were defined by etiologic disparities among PCa patients; this correlation is different among AA men compared to EA men. Understanding PCa and specifically CRPC disparities requires a better understanding of the race-specific differences in prostate tumor biology, molecules leading to prostate inflammation, and the mechanisms associated with CRPC therapeutic resistance and its aggressive phenotype. Citation Format: Adaugo Queen Ohandjo, Courtney Dill, Chen Dongquan, James W. Lillard, Jr.. Regulation of CXCR5-CXCL13 signaling in prostate cancer etiologic disparities [abstract]. In: Proceedings of the Tenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2017 Sep 25-28; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2018;27(7 Suppl):Abstract nr B56.

Abstract LB-199: Role of ASCL1 in neuroendocrine prostate cancer progression

Abstract INTRODUCTION: Metastatic prostate cancer is a lethal disease. Many patients develop a form of the disease resistant to Androgen Deprivation Therapy (ADT) called castration resistant prostate cancer (CRPC), and androgen refractory tumors emerge. A subset of these involve gaining small cell and neuroendocrine (NE) features, resulting in neuroendocrine prostate cancer (NEPC). The identification of key drivers and the mechanism of emergence is critical, as NEPC is associated with poor outcomes. Of interest is the neuron lineage differentiation gene achaete-scute complex homologue 1 (ASCL1). Mouse models of small cell lung cancer (SCLC) show ASCL1 as a key promoter of tumor growth in vivo. While there is overlap between SCLC and NEPC (inactivation of RB1 and TP53, ASCL1 overexpression (OE)), it's unclear if ASCL1 contributes to transdifferentiation of prostate epithelium into NEPC. In addition to genetic drivers, defined soluble factors can promote reprogramming of fibroblasts into neurons. We thus hypothesize that ASCL1 in combination with soluble factors may promote transdifferentiation of prostate epithelium to NEPC. METHODS: CRISPR technology is used to knockout (KO) RB1 and TP53 in LNCaP cells. Lentiviral vector is used to OE for ASCL1 or RFP in LNCaP or LNCap p53/RB1 KO cells. Gene expression for AR, AR target genes, neuronal, and NE genes is measured via qRT-PCR and Western. Regular FBS or neuronal media containing either FGF2/BDNF/NTF3 or all soluble factors is used for cell culture. RESULTS: RNAseq data from metastatic AR+ CRPC, AR- NEPC, and SCLC tumors and cell lines shows OE of ASCL1 in AR- NEPC and SCLC. LNCaP ASCL1 OE cells show no change in cellular growth in FBS, CSS, or NM + supplements (BDNF, FGF2, NT3) compared to control. However, LNCaP p53/RB1 KO ASCL1 OE cells + 10μM Enzalutamide (ENZ) proliferated similar to the cells without any drug treatment when cultured in NM + sup (96h, p=0.999). Both LNCaP ± ASCL1 and LNCaP p53/RB1 KO ± ASCL1 cells grown in NM + sup show significantly decreased AR and AR target gene expression (~10 fold, p&amp;lt; 0.05). FGF8 (~5 fold), SOX2 (&amp;gt;300 fold), and SYP (&amp;gt;10 fold) gene expression increased significantly (p&amp;lt;0.05) in LNCaP ± ASCL1 grown in NM + sup. LNCaP p53/RB1 KO ± ASCL1 OE in NM + sup show ~3-6 fold increase in SOX2 and ~30-50 fold increase in FGF9 compared to cells cultured in FBS. CONCLUSION: Loss of TP53 and RB1 are not sufficient to induce transdifferentiation to a NEPC state, but ASCL1 OE induced the expression of SOX2 and SYP that may trigger the process. Microenvironment effects operating through paracrine factors induced the expression of a NE gene program and reduced AR expression. Future studies will investigate the role of ASCL1 in promoting resistance to ENZ in prostate adenocarcinoma cells as well as its role in in vivo tumor growth. ASCL1, NEUROD1, and MYTL1 that are OE in NEPC and SCLC in combination with individual soluble factors will be used to delineate the mechanism required for the transdifferentiation process. Citation Format: Seema Sinha, Michael D. Nyquist, Alexandra Corella, Ilsa Coleman, Peter S. Nelson. Role of ASCL1 in neuroendocrine prostate cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-199.

Crosstalk of the Androgen Receptor with Transcriptional Collaborators: Potential Therapeutic Targets for Castration-Resistant Prostate Cancer

Prostate cancer is the second leading cause of death from cancer among males in Western countries. It is also the most commonly diagnosed male cancer in Japan. The progression of prostate cancer is mainly influenced by androgens and the androgen receptor (AR). Androgen deprivation therapy is an established therapy for advanced prostate cancer; however, prostate cancers frequently develop resistance to low testosterone levels and progress to the fatal stage called castration-resistant prostate cancer (CRPC). Surprisingly, AR and the AR signaling pathway are still activated in most CRPC cases. To overcome this problem, abiraterone acetate and enzalutamide were introduced for the treatment of CRPC. Despite the impact of these drugs on prolonged survival, CRPC acquires further resistance to keep the AR pathway activated. Functional molecular studies have shown that some of the AR collaborative transcription factors (TFs), including octamer transcription factor (OCT1), GATA binding protein 2 (GATA2) and forkhead box A1 (FOXA1), still stimulate AR activity in the castration-resistant state. Therefore, elucidating the crosstalk between the AR and collaborative TFs on the AR pathway is critical for developing new strategies for the treatment of CRPC. Recently, many compounds targeting this pathway have been developed for treating CRPC. In this review, we summarize the AR signaling pathway in terms of AR collaborators and focus on pyrrole-imidazole (PI) polyamide as a candidate compound for the treatment of prostate cancer.

Targeting intratumoral androgens: statins and beyond.

While initially effective, androgen deprivation therapy (ADT) is not curative, and nearly all men with advanced prostate cancer will eventually progress to the more resistant, and ultimately lethal form of the disease, so called castration-resistant prostate cancer (CRPC). The maintenance of androgens within the prostate cancer microenvironment likely represents one of the key mechanisms by which this transition from hormone-sensitive to CRPC occurs. This can be accomplished either through intratumoral androgen biosynthesis or the active transport of androgens and androgenic precursors into the tumor microenvironment. More recently, preclinical and clinical data supported therapeutic strategies that seek to target these two mechanisms, either through the use of drugs that impair androgen biosynthesis (e.g. inhibiting the steroidogenic enzymes CYP17 and AKR1C3 with abiraterone and indomethacin, respectively) or drugs that inhibit the SLCO transporters responsible for importing androgens (e.g. statins).

BET bromodomain-mediated interaction between ERG and BRD4 promotes prostate cancer cell invasion

Prostate cancer (PCa) that becomes resistant to hormone castration and next-generation androgen receptor (AR)-targeted therapies, called castration-resistant prostate cancer (CRPC), poses a significant clinical challenge. A better understanding of PCa progression and key molecular mechanisms could bring novel therapies to light. One potential therapeutic target is ERG, a transcription factor aberrantly up-regulated in PCa due to chromosomal rearrangements between androgen-regulated gene TMPRSS2 and ERG. Here we show that the most common PCa-associated truncated ERG T1–E4 (ERGΔ39), encoded by fusion between TMPRSS2 exon 1 and ERG exon 4, binds to bromodomain-1 (BD1) of bromodomain containing protein 4 (BRD4), a member of the bromodomain and extraterminal domain (BET) family. This interaction is partially abrogated by BET inhibitors JQ1 and iBET762. Meta-analysis of published ERG (T1–E4) and BRD4 chromatin immunoprecipitation-sequencing (ChIP-seq) data demonstrates overlap in a substantial portion of their binding sites. Gene expression profile analysis shows some ERG-BRD4 co-target genes are upregulated in CRPC compared to hormone-naïve counterparts. We provide further evidence that ERG-mediated invasion of PCa cells was significantly enhanced by an acetylation-mimicking mutation in ERG that augments the ERG-BRD4 interaction. Our findings reveal that PCa-associated ERG can interact and co-occupy with BRD4 in the genome, and suggest this druggable interaction is critical for ERG-mediated cell invasion and PCa progression.