Prostate Cancer Patient Samples Research Articles

Abstract 2426: Liquid biopsy for a predictive biomarker of resistance to immunotherapy

Abstract Immunotherapy has become a mainstay for cancer treatment. However, immune editing is a well-known resistance paradigm that limits the efficacy of immunotherapy in many patients. One type of immune editing that occurs in 1/6 of all cancer patients, with prevalence over 40% in some cancer types, is human leukocyte antigen loss of heterozygosity (HLA LOH). Liquid biopsies provide a non-invasive and inexpensive way of guiding treatment decision-making. We have developed a liquid biopsy assay for detecting HLA LOH in cancer patients, with the goal of utilizing the assay for deciding whether immunotherapy is the right course of treatment for a given patient. The assay was tested utilizing sample sets from cancer patients, where each sample set from a patient included a solid tumor biopsy, a liquid biopsy plasma sample, and PBMC sample for control. Tumor HLA LOH results were used for ground truth, and HLA LOH results from the liquid biopsy sample were compared to those from the tumor sample from the same patient. Whole exome sequencing (WES) was performed on tumor DNA, cell-free DNA (cfDNA) from plasma, and germline DNA from PBMCs, and we ran our novel liquid biopsy HLA LOH detection algorithm on the plasma WES data. Standard copy number variant (CNV) calling tools were utilized for calling HLA LOH from the tumor sequencing data. In both cases - tumor and plasma - germline PBMC DNA was used as control. We tested the liquid biopsy HLA LOH detection method on sample sets from 2 HPV-negative primary head and neck cancer patients, 14 castration-resistant prostate cancer patients, and 27 metastatic breast cancer patients. The samples from the head and neck cancer patients were obtained from patients on clinical trials at NCI, while WES data from prostate cancer patient samples and breast cancer patient samples were downloaded from NCBI Database of Genotypes and Phenotypes (dbGaP) after applying for access to dataset phs001417.v1.p1 (Adalsteinsson, et al., Nature Communications, 2017). The method for liquid biopsy HLA LOH detection utilizes a novel mathematical framework that takes into account biological and experimental variables to generate allele-specific HLA LOH information from sequencing data. In the first two cohorts tested - the head and neck cancer cohort and the prostate cancer cohort - the method was 100% consistent when comparing liquid biopsy HLA LOH results from our method to CNV calling results from matched tumors (4 true positives and 36 true negatives; 0 false negatives and 0 false positives). In the breast cancer cohort, some false negatives and false positives were observed (6 true positives and 48 true negatives; 5 false negatives and 8 false positives). Experiments are ongoing in a CLIA lab to establish sensitivity, specificity, and limit of detection (LoD) for the assay. Upon improvements and validation of the assay, the goal is to utilize the liquid biopsy HLA LOH detection method in the clinic for treatment selection in the context of immunotherapy. Citation Format: Andrew Sinkoe, James L. Gulley. Liquid biopsy for a predictive biomarker of resistance to immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2426.

Abstract 2011: MAOA Drives Anti Androgen Therapy Resistance in Advanced Prostate Cancer by Conferring Neuroendocrine Plasticity via a Twist1 BRN2 Signaling Pathway

Abstract Background: Therapy resistance in cancer is often linked to cancer cell state or lineage changes. In prostate cancer (PCa), a subset of castration-resistant prostate cancer (CRPC) loses reliance on the androgen receptor (AR) signaling and gains neuroendocrine (NE) traits through a lineage switch along disease progression. However, the molecular mechanisms driving such cellular lineage plasticity remain unclear. This study investigated the functional and mechanistic role of monoamine oxidase A (MAOA) in driving adenocarcinoma (adeno)-to-NE lineage conversion in CRPC cells upon enzalutamide (ENZ), a FDA-approved newer-generation antiandrogen drug, and evaluated the efficacy of MAOA inhibitors for treating CRPC and overcoming ENZ resistance.Methods: ENZ-resistant C4-2B and CWR-R1 cells (C4-2BENZR and CWR-R1ENZR) CRPC cells were transfected with a PSA promoter-driven GFP expression construct for isolating a PSAlo/− cell population distinct from PSAhi cells, which was used for manipulation of MAOA expression levels and subsequent functional assays in vitro and in vivo. The MAOA expression levels were determined and correlated with NE parameters in PCa clinical samples by immunohistochemistry and data mining of multiple publicly available clinical datasets. Results: MAOA protein expression was significantly upregulated in the PSAlo/− ENZ-resistant cell population, accompanied by concomitant activation of NE markers and downregulation of luminal markers including AR and AR targets, compared to the PSAhi counterpart. Elevated MAOA expression was also found in PCa patient samples associated with NE features from multiple independent cohorts. Silencing MAOA suppressed the proliferation, migration, invasion, stem-like properties and NE plasticity of both PSAlo/- C4-2BENZR and CWR-R1ENZR cells. Moreover, co-culturing adeno LNCaP or C4-2B cells with MAOA-silenced PSAlo/- cells exhibiting a repressed secretory phenotype attenuated acquired induction of NE markers and proliferation of adeno cells as compared to controls. Mechanistically, MAOA induces Twist1, which directly activates the transcription and expression of BRN2, a master neural transcription factor known to confer NE differentiation and anti-AR therapy resistance in CRPC. Further, pharmacological inhibition of MAOA greatly enhanced the growth-inhibitory efficacy of ENZ with ENZ sensitivity restored in ENZ-resistant LuCaP PC PDX-derived organoids as well as a PSAlo/− CWR-R1ENZR xenograft mouse model.Conclusion: Our results suggest MAOA as a potential therapeutic target for reversing ENZ resistance in CRPC treatment by blockade of NE transdifferentiation.Funding Acknowledgements: This work was supported by the NIH/NCI grants R37CA233658 and R01CA258634 (to B. Wu) and the DOD Department of Defense EIRA award W81XWH-21-1-0218 (to J. Wei) Citation Format: Jing Wei, Jing Wang, Chia-hui Chen, Wen Guan, Boyang Wu. MAOA Drives Anti Androgen Therapy Resistance in Advanced Prostate Cancer by Conferring Neuroendocrine Plasticity via a Twist1 BRN2 Signaling Pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2011.

Abstract 253: Investigating key molecular players in putative stem cell subpopulations of prostate cancer

Abstract Background: Androgen deprivation therapy is the standard treatment for prostate cancer (PCa). Nevertheless, despite initial effectiveness, pre-existing cancer stem cell (CSC) populations invariably lead to incurable castration-resistant prostate cancer. CSCs are a subset of cancer cells possessing self-renewal properties, driving tumor progression and regrowth. CD44+ PCa cells exhibit more stemness features and are enriched in tumorigenic and metastatic progenitor cells. Here, we aim to explore different subpopulations in tumors based on levels of CD44 expression and investigate whether they have distinct molecular properties and functional characteristics. Material and Method: The number of CD44+ cells was evaluated in a tissue microarray from primary prostate cancer patient samples (EMPACT cohort) with clinical follow-up. Flow cytometry sorted the CRPC model LAPC9 tumor into CD44 high (CD44-H) and CD44 low (CD44-L) cells. RNA sequencing was performed on these subpopulations to explore their transcriptomic profiles. CD44 expression was validated at the cDNA and protein levels using qPCR and Western blot (WB) analysis. Sorted cells were maintained as organoids in vitro. To trace the dynamics of CD44-H and CD44-L subpopulations in vivo, LAPC9 tumor was labeled by fluorescent and luciferent markers. The CD44 status was determined by flow cytometry when tumor growth. Results: Patients with elevated expression of CD44 (higher number of CD44+ cells) at the time of surgery exhibited a greater propensity for clinic progression (5-year progression-free survival: 75% vs 95%, P=0.03). Furthermore, CD44-H cell ratio increased in the LAPC9 after castration, indicating that CD44-H cells can survive after treatment. Subsequent WB analysis confirmed that CD44 was highly expressed in sorted CD44-H cells, validating the flow cytometry results. Analysis of the CD44 RNA-seq data showed CD44 transcript variants CD44v10 (CD44-201) and CD44v7-10 (CD44-209) were notably upregulated in CD44-H cells. In organoid culture, sorted CD44-H cells displayed enhanced formation, indicating they possessed higher proliferative capacity and clonogenicity than CD44-L cells. Furthermore, when GFP-labeled CD44-H cells and RFP-labeled CD44-L cells were recombined in vivo, CD44-H cells exhibited robust proliferation, while CD44-L cells transitioned to a CD44hi state to facilitate tumor growth. Moreover, those GFP and RFP subpopulations displayed the same CD44hi cell ratio at the endpoint. Conclusion: Elevated CD44 expression is related to an increased risk in primary PCa. In addition, CD44-H cells exhibit high tumorigenicity in vitro and in vivo and can convert to each other. Moreover, the ratio of CD44-H cells in tumor at endpoint is consistent despite the starting CD44 expression status. Furthermore, the upregulation of CD44v10 and v7-10 in the CD44-H subpopulation may promote tumor formation and metastasis. Citation Format: Wanli Cheng, Marta De Menna, Francesco Bonollo, Panagiotis Chouvardas, George N. Thalmann, Sofia Karkampouna, Marianna Kruithof Julio. Investigating key molecular players in putative stem cell subpopulations of prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 253.

Abstract 2993: TmiS: A prognostic indicator for prostate cancer survival based on total tumor cell miRNA levels

Abstract Background: MicroRNAs (miRNAs) are small noncoding RNAs that bind mRNA and inhibit translation or encourage degradation. MiRNAs play a significant regulatory role, with approximately 60% of protein-coding genes harboring miRNA binding sites. MiRNA dysregulation is associated with tumor onset, growth, and metastasis. These important regulatory RNAs have been studied as potential cancer biomarkers, yet the widespread adoption of any miRNA signature has been hindered by the variable nature of miRNA targeting, which is highly context specific. Total tumor cell mRNA content, or TmS, has been shown to have potential as a pan-cancer prognostic indicator. Here we expand the TmS framework using deconvolved miRNA expression to calculate TmiS, an estimate of total tumor-cell miRNA content and investigate the utility of TmiS as a prognostic marker in prostate cancer. Methods: Whole exome sequencing and miRNA sequencing, along with clinical annotations were downloaded for prostate cancer patient samples from The Cancer Genome Atlas (TCGA). Sample purity and ploidy were estimated from exomes using ASACT and ABSOLUTE. Tumor miRNA proportion was estimated using our previously developed miRNA deconvolution method DeMixMir, and TmiS, the total miRNA content per haploid genome per tumor cell, was calculated for each sample. Patients were separated by Gleason category and were binarized into High-TmiS and Low-TmiS within samples with Gleason 7 and Gleason 8+ scores separately. Results: We find Low-TmiS patients to have significantly better prognosis in both Gleason 7 (P = 0.04) and Gleason 8+ (P = 0.01) prostate cancer. We confirm that TmiS is indeed an aggregate measure of total miRNA levels, with no strong correlations observed with any one miRNA. We identify differentially expressed miRNAs and mRNAs between high and low TmiS, and find distinct enriched pathways between Gleason 7 and Gleason 8+ samples, and that several of the differentially expressed miRNAs are well-characterized cancer-related transcripts. Conclusions: In spite of their important regulatory function, the variable and context specific nature of miRNA targeting has been a barrier to their implementation as a robust biomarker. We find TmiS to be a measure of total miRNA dysregulation, and that patients with high total miRNA content show poorer survival within prostate samples graded at Gleason 7 (as well as Gleason 8+), which has been a challenging group for further risk classification. In summary, while the consequences of miRNA dysregulation are subtype specific, we find that by measuring total tumor cell miRNA, TmiS has potential as a robust prognostic indicator independent cellular context. Citation Format: Matthew Montierth, Kinga Németh, George A. Calin, Wenyi Wang. TmiS: A prognostic indicator for prostate cancer survival based on total tumor cell miRNA levels [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2993.

The Effect of HMGB1 and HMGB2 on Transcriptional Regulation Differs in Neuroendocrine and Adenocarcinoma Models of Prostate Cancer.

Human high-mobility group-B (HMGB) proteins regulate gene expression in prostate cancer (PCa), a leading cause of oncological death in men. Their role in aggressive PCa cancers, which do not respond to hormonal treatment, was analyzed. The effects of HMGB1 and HMGB2 silencing upon the expression of genes previously related to PCa were studied in the PCa cell line PC-3 (selected as a small cell neuroendocrine carcinoma, SCNC, PCa model not responding to hormonal treatment). A total of 72% of genes analyzed, using pre-designed primer panels, were affected. HMGB1 behaved mostly as a repressor, but HMGB2 as an activator. Changes in SERPINE1, CDK1, ZWINT, and FN1 expression were validated using qRT-PCR after HMGB1 silencing or overexpression in PC-3 and LNCaP (selected as an adenocarcinoma model of PCa responding to hormonal treatment) cell lines. Similarly, the regulatory role of HMGB2 upon SERPINE1, ZWINT, FN1, IGFPB3, and TYMS expression was validated, finding differences between cell lines. The correlation between the expression of HMGB1, HMGB2, and their targets was analyzed in PCa patient samples and also in PCa subgroups, classified as neuroendocrine positive or negative, in public databases. These results allow a better understanding of the role of HMGB proteins in PCa and contribute to find specific biomarkers for aggressive PCa.

Impaired monocyte-derived dendritic cell phenotype in prostate cancer patients: A phenotypic comparison with healthy donors.

Dendritic cells (DCs) play a crucial role in immunity. Research on monocyte-derived DCs (Mo-DCs) cancer vaccines is in progress despite limited success in clinical trials. This study focuses on Mo-DCs generated from prostate cancer (PCA) patients, comparing them with DCs from healthy donors (HD-DCs). Mo-DCs were isolated from PCA patient samples, and their phenotype was compared to HD-DCs. Key parameters included monocyte count, CD14 expression, and the levels of maturation markers (HLA-DR, CD80, CD86) were assessed. PCA samples exhibited a significantly lower monocyte count and reduced CD14 expression compared to healthy samples (p ⟨ 0.0001). Additionally, PCA-DCs expressed significantly lower levels of maturation markers, including HLA-DR, CD80, and CD86, when compared to HD-DCs (p = 0.123, p = 0.884, and p = 0.309, respectively). The limited success of DC vaccines could be attributed to impaired phenotypic characteristics. These observations suggest that suboptimal characteristics of Mo-DCs generated from cancer patient blood samples might contribute to the limited success of DC vaccines. Consequently, this study underscores the need for alternative strategies to enhance the features of Mo-DCs for more effective cancer immunotherapies.

Gut microbiota-derived short-chain fatty acids promote prostate cancer progression via inducing cancer cell autophagy and M2 macrophage polarization

We have previously demonstrated abnormal gut microbial composition in castration-resistant prostate cancer (CRPC) patients, here we revealed the mechanism of gut microbiota-derived short-chain fatty acids (SCFAs) as a mediator linking CRPC microbiota dysbiosis and prostate cancer (PCa) progression. By using transgenic TRAMP mouse model, PCa patient samples, in vitro PCa cell transwell and macrophage recruitment assays, we examined the effects of CRPC fecal microbiota transplantation (FMT) and SCFAs on PCa progression. Our results showed that FMT with CRPC patients’ fecal suspension increased SCFAs-producing gut microbiotas such as Ruminococcus, Alistipes, Phascolarctobaterium in TRAMP mice, and correspondingly raised their gut SCFAs (acetate and butyrate) levels. CRPC FMT or SCFAs supplementation significantly accelerated mice's PCa progression. In vitro, SCFAs enhanced PCa cells migration and invasion by inducing TLR3-triggered autophagy that further activated NF-κB and MAPK signalings. Meanwhile, autophagy of PCa cells released higher level of chemokine CCL20 that could reprogramme the tumor microenvironment by recruiting more macrophage infiltration and simultaneously polarizing them into M2 type, which in turn further strengthened PCa cells invasiveness. Finally in a cohort of 362 PCa patients, we demonstrated that CCL20 expression in prostate tissue was positively correlated with Gleason grade, pre-operative PSA, neural/seminal vesical invasion, and was negatively correlated with post-operative biochemical recurrence-free survival. Collectively, CRPC gut microbiota-derived SCFAs promoted PCa progression via inducing cancer cell autophagy and M2 macrophage polarization. CCL20 could become a biomarker for prediction of prognosis in PCa patients. Intervention of SCFAs-producing microbiotas may be a useful strategy in manipulation of CRPC.

Influence of ADT on B7-H3 expression during CRPC progression from hormone-naïve prostate cancer.

Androgen deprivation therapy (ADT) is the standard care for advanced prostate cancer (PCa) patients. Unfortunately, although tumors respond well initially, they enter dormancy and eventually progress to fatal/incurable castration-resistant prostate cancer (CRPC). B7-H3 is a promising new target for PCa immunotherapy. CD276 (B7-H3) gene has a presumptive androgen receptor (AR) binding site, suggesting potential AR regulation. However, the relationship between B7-H3 and AR is controversial. Meanwhile, the expression pattern of B7-H3 following ADT and during CRPC progression is largely unknown, but critically important for identifying patients and determining the optimal timing of B7-H3 targeting immunotherapy. In this study, we performed a longitudinal study using our unique PCa patient-derived xenograft (PDX) models and assessed B7-H3 expression during post-ADT disease progression. We further validated our findings at the clinical level in PCa patient samples. We found that B7-H3 expression was negatively regulated by AR during the early phase of ADT treatment, but positively associated with PCa proliferation during the remainder of disease progression. Our findings suggest its use as a biomarker for diagnosis, prognosis, and ADT treatment response, and the potential of combining ADT and B7-H3 targeting immunotherapy for hormone-naïve PCa treatment to prevent fatal CRPC relapse.

Abstract 442: Developing a lipogenesis inhibitor for prostate cancer

Abstract Background: Prostate cancer (PC) is the single most common and second most lethal cancer in men. Despite therapeutic advances in androgen receptor (AR)-targeting agents, progression to lethal, drug-resistant, castration-resistant prostate cancer (CRPC) remains a major clinical problem. Thus, there is an unmet need for novel treatment approaches and novel, druggable therapeutic targets in metastatic CRPC. Profiling of PC patient samples shows increases in two master regulators of lipogenesis-sterol regulatory binding proteins 1 and 2 (SREBP1 and SREBP2)-and their transcriptional targets. Overexpression of SREBP1 and SREBP2 and their target genes has been associated with tumor aggressiveness, poor clinical outcomes, and drug resistance in PC. The activation and nuclear translocation of SREBPs is tightly regulated by SREBP cleavage-activating protein (SCAP). We propose targeting SCAP will simultaneously block the activation and subsequent activity of all three SREBPs and that this represents a promising therapeutic strategy to treat CRPC. Methods: To increase our understanding of SREBP biology in PC cells, we defined the cistrome of SREBPs across multiple PC cell lines via ChIP-Seq. We compared the transcriptomic profiles of genetic targeting of SREBP via siRNA and pharmacological targeting via the novel SCAP inhibitor, SCAPi. We evaluated the effect of SCAPi on cell viability, cell invasion, and AR-signaling in multiple PC cell lines using immunoblotting, luciferase reporters, flow cytometry, MTT, and invasion assays. Additionally, we will evaluate the anticancer activity and safety profile of our novel SCAPi using CDX mouse models. Results: We found that inhibition of SCAP via siRNA and via SCAPi both yielded similar gene signatures, particularly the perturbation of cell cycle and lipogenesis genes. SCAPi dramatically reduces cell viability, migration, invasion, and expression of both AR- and SREBP-target genes in multiple PC cell lines. Through flow cytometry (Annexin V) and western blots (cleaved PARP) we found SCAPi induces apoptosis within 48 hours in PC cells. Pilot studies in tumor-bearing mice show SCAPi significantly increases survival without inducing animal weight loss. Conclusions: There is a critical need for novel targets in PC, and dysregulated lipogenesis is an untargeted oncogenic pathway. Our work furthers the field’s understanding of hijacked lipogenesis in PC and paves the way for a first-in-class inhibitor of lipogenesis to treat lethal PC. Citation Format: Dallin Lowder, Jin Na Shin, Maria E. Ruiz-Echartea, Darlene Skapura, Jenny Deng, Aleksandra Rusin, Christel Davis, Erik Ehli, Cristian Coarfa, Michael Ittmann, Salma Kaochar. Developing a lipogenesis inhibitor for prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 442.

MP20-07 NPTX1 IS A NOVEL SERUM BIOMARKER INDUCED BY ARPI TREATED PROSTATE CANCER AND ENRICHED IN LINEAGE PLASTICITY WITH BRN2 HIGH

You have accessJournal of UrologyCME1 Apr 2023MP20-07 NPTX1 IS A NOVEL SERUM BIOMARKER INDUCED BY ARPI TREATED PROSTATE CANCER AND ENRICHED IN LINEAGE PLASTICITY WITH BRN2 HIGH Takeshi Namekawa, Joshua Scurll, Maxim Kobelev, Dwaipayan Ganguli, Olena Sivak, Martin Gleave, Vancouver, Canada, Eva Corey, Colm Morrissey, and Amina Zoubeidi Takeshi NamekawaTakeshi Namekawa More articles by this author , Joshua ScurllJoshua Scurll More articles by this author , Maxim KobelevMaxim Kobelev More articles by this author , Dwaipayan GanguliDwaipayan Ganguli More articles by this author , Olena SivakOlena Sivak More articles by this author , Martin GleaveMartin Gleave More articles by this author , Vancouver Vancouver More articles by this author , Canada Canada More articles by this author , Eva CoreyEva Corey More articles by this author , Colm MorrisseyColm Morrissey More articles by this author , and Amina ZoubeidiAmina Zoubeidi More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003245.07AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Androgen receptor (AR) pathway inhibition is the first-line therapy for metastatic prostate cancer (PCa). However, tumors invariably develop resistance to ARPI. We previously identified a transcription factor Brain-2 (BRN2), encoded by the gene POU3F2, as a master driver of NEPC which is an aggressive form of AR-independent phenotypes treatment resistant PCa. In this study, we identified a surrogate biomarker of BRN2 activity to monitor the progression of treatment resistant PCa. METHODS: To identify BRN2 serum marker, we analyzed BRN2 ChIPseq data from 2 NEPC and 2 neural-type lung squamous cell carcinoma (nLUSC) cell lines with a focus on shared BRN2 peaks. Annotated peaks from enhancers (EnhancerAtlas) and promoters (genes within 20kb) were selected for secreted proteins and were ranked by correlation with BRN2 expression in PCa patients. Validation of protein expression was performed by western blot. R-PLEX Assay kit was used to measure concentrations in culture media from NCI-H660 cells and in serum from mice with NCI-H660 xenograft or PDX tumors and from human PCa patients. RESULTS: We identified 51 candidate serum biomarkers for BRN2 activity (or expression?) using the methods described above. These biomarkers were ranked based on their expression and correlation with BRN2 expression in PCa patient samples across four public data sets. NPTX1 was identified as the top biomarker of BRN2 expression. We further validated association of NPTX1 and BRN2 expression by BRN2 overexpression in MR42D and 22Rv1, indicating that BRN2 positively regulates NPTX1 expression. Next, we showed that NPTX1 is present in culture media from NCI-H660 cells, and that NPTX1 serum concentration positively correlated with tumor volume in mice with NCI-H660 xenografts and with NPTX1 mRNA expression in LuCaP PDX models. Importantly, evaluation of patients’ samples showed that NPTX1 levels were high in 26/35 CRPC serum samples vs levels in serum of healthy volunteers, and that the NPTX1 serum levels were highest in 4/6 patients with high POU3F2 tumor expression. CONCLUSIONS: We identified and validated NPTX1 as a serum marker that can be readily detected in serum from NEPC patients with BRN2high tumours. Source of Funding: U.S. Army Medical Research and Development Command(W81XWH1810689) © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e277 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Takeshi Namekawa More articles by this author Joshua Scurll More articles by this author Maxim Kobelev More articles by this author Dwaipayan Ganguli More articles by this author Olena Sivak More articles by this author Martin Gleave More articles by this author Vancouver More articles by this author Canada More articles by this author Eva Corey More articles by this author Colm Morrissey More articles by this author Amina Zoubeidi More articles by this author Expand All Advertisement PDF downloadLoading ...

PD04-12 RADIOTHERAPEUTIC TREATMENT OF PROSTATE CANCER CELLS PROMOTES THE RELEASE OF POTENTIALLY DELETERIOUS AND IMMUNOLOGICALLY ACTIVE EXTRACELLULAR VESICLES

You have accessJournal of UrologyCME1 Apr 2023PD04-12 RADIOTHERAPEUTIC TREATMENT OF PROSTATE CANCER CELLS PROMOTES THE RELEASE OF POTENTIALLY DELETERIOUS AND IMMUNOLOGICALLY ACTIVE EXTRACELLULAR VESICLES Ryan Molony, Sarah Kerns, Brian Marples, Emmanuel Oshodi, YuhChyau Chen, and Yi-Fen Lee Ryan MolonyRyan Molony More articles by this author , Sarah KernsSarah Kerns More articles by this author , Brian MarplesBrian Marples More articles by this author , Emmanuel OshodiEmmanuel Oshodi More articles by this author , YuhChyau ChenYuhChyau Chen More articles by this author , and Yi-Fen LeeYi-Fen Lee More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003228.12AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: One in four prostate cancer (PCa) patients will develop late hematuria and other delayed bladder toxicities following radiotherapy (RT) through poorly understood mechanisms. Membrane-enclosed extracellular vesicles (EVs) are released from tumor and non-tumor cells at baseline, and their composition can change markedly in response to stimuli. The impact of RT-induced EV (RT-EV) release from PCa cells or other cell populations in the tumor microenvironment, including immune cells, have yet to be characterized. Here, we examined the dynamics and composition of RT-EVs released by PCa cells and immune cells in response to irradiation, and their association with bladder tissue toxicity. METHODS: Urinary EV cargo proteins in pre- and post-RT PCa patient samples were analyzed and compared by LC-MS/MS. The impact of RT on EV release kinetics was analyzed by nanoparticle tracking analysis. RT-EVs and naïve EVs were collected from PCa patients and PCa cells lines (C4-2 and LNCaP). Their mechanistic effects on normal SV-HUC urothelial cells were assessed, including cellular viability, reactive oxygen species (ROS) production, and cytokine release. The effects of RT-EVs and RT on the activation of immune cell populations were monitored by treating Jurkat T cells or HL-60-derived neutrophils with RT-EVs or irradiating these cells and evaluating activation, cytokine release, and ROS production. RESULTS: The post-RT urinary EVs of a PCa patient who later developed hematuria were enriched for potentially caustic neutrophil-associated proteins relative to EVs from a hematuria-free patient. RT significantly enhanced the release of EVs from PCa cell lines and neutrophils, and these RT-EVs or direct irradiation promoted increased ROS production by HL-60 neutrophils, Jurkat T cells, and SV-HUC urothelial cells while also increasing interleukin (IL)-1β release from SV-HUC cells consistent with the induction of a damage-associated innate immune response. CONCLUSIONS: These results suggest RT can provoke the release of immunologically active and potentially deleterious EVs from PCa cells and local immune cell populations that can contribute to oxidative stress and inflammatory response induction in local and distant cell populations including neutrophils, T cells, and urothelial cells, potentially driving a feedback loop exacerbating RT-associated tissue damage. Source of Funding: University of Rochester Medical Center Departmental Funding © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e146 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ryan Molony More articles by this author Sarah Kerns More articles by this author Brian Marples More articles by this author Emmanuel Oshodi More articles by this author YuhChyau Chen More articles by this author Yi-Fen Lee More articles by this author Expand All Advertisement PDF downloadLoading ...

Downstream of kinase 3 promotes proliferation and inhibits apoptosis of prostate cancer via the NF-κB signaling pathway.

Downstream of kinase 3 (DOK3) is involved primarily with immune cell infiltration. Recent research reported the role of DOK3 in tumor progression, with opposite effects in lung cancer and gliomas; however, its role in prostate cancer (PCa) remains elusive. This study aimed to explore the role of DOK3 in PCa and to determine the mechanisms involved. To investigate the functions and mechanisms of DOK3 in PCa, we performed bioinformatic and biofunctional analyses. Samples from patients with PCa were collected from West China Hospital, and 46 were selected for the final correlation analysis. A lentivirus-based short hairpin ribonucleic acid (shRNA) carrier was established for silencing DOK3. A series of experiments involving the cell counting kit-8, bromodeoxyuridine, and flow cytometry assays were performed to identify cell proliferation and apoptosis. Changes in biomarkers from the nuclear factor kappa B (NF-κB) signaling pathway were detected to verify the relationship between DOK3 and the NF-κB pathway. A subcutaneous xenograft mouse model was performed to examine phenotypes after knocking down DOK3 in vivo. Rescue experiments with DOK3 knockdown and NF-κB pathway activation were designed to verify regulating effects. DOK3 was up-regulated in PCa cell lines and tissues. In addition, a high level of DOK3 was predictive of higher pathological stages and worse prognoses. Similar results were observed with PCa patient samples. After silencing DOK3 in PCa cell lines 22RV1 and PC3, cell proliferation was significantly inhibited while apoptosis was promoted. Gene set enrichment analysis revealed that DOK3 function was enriched in the NF-κB pathway. Mechanism experiments determined that knockdown of DOK3 suppressed activation of the NF-κB pathway, increased the expressions of B-cell lymphoma-2 like 11 (BIM) and B-cell lymphoma-2 associated X (BAX), and decreased the expression of phosphorylated-P65 and X-linked inhibitor of apoptosis (XIAP). In the rescue experiments, pharmacological activation of NF-κB by tumor necrosis factor-α (TNF-α) partially recovered cell proliferation after the knockdown of DOK3. Our findings suggest that overexpression of DOK3 promotes PCa progression by activating the NF-κB signaling pathway.

Erythroblast transformation-specific transcription factor fusions in prostate cancer.

224 Background: Common drivers in advanced prostate cancer (PC) involve fusions of the 3’ DNA binding domain-containing region of an Erythroblast Transformation Specific (ETS) transcription factor gene with a 5’ region of another gene, often one that is androgen-regulated. Previous work indicates that PCs harboring TMPRSS2:ERG fusions are more dependent on androgen signaling, and men with such tumors may, therefore, be more responsive to the effects of androgen deprivation therapy than men lacking this fusion. In this study, we examined the frequency of fusions involving ETS-family genes, including TMPRSS2:ERG, and determined how often such fusions would be missed if detection relied solely on DNA sequencing. Methods: To identify fusions and compare DNA-only versus DNA plus RNA sequencing, we utilized the Oncomap ExTra genomic profiling assay. This assay performs whole-exome, whole-transcriptome DNA and RNA sequencing of tumor and matched normal samples to identify somatic alterations in tumors. Single-nucleotide variants, indels, copy number alterations, alternative transcripts, and gene fusions are all detected. We specifically searched for fusions involving ETS transcription factor genes ERG and ETV1- 7. Results: A total of 512 PC patient samples assayed between April 2018 and July 2022 were included in the analysis; 226 ETS fusions were present in 223 (43.6%) patients; 3 patients carried two fusions. There were 196 ERG fusions including 185 (36.1%) patients having the familiar TMPRSS2: ERG fusion and 8 (1.6%) patients with a SLC45A3: ERG fusion, which is known to be associated with particularly poor prognosis. ETV1, 4, and 5 fusions were found in 29 (5.7%) patients and involved 12 different 5’ partner genes, the most common of which were SLC45A3 (6 fusions) and CANT1 (4 fusions). The two partner genes were on the same chromosome in 192 fusions, with 190 requiring a single deletion to create the fusion and 2 requiring a single inversion. For the 34 fusions involving genes on different chromosomes, a single translocation would be sufficient to produce the fusion gene in 23 cases; in 11 cases more than one structural rearrangement would be required. A total of 66 (29.6%) fusions were not detected in the DNA sequencing data, including 40 (21.6%) TMPRSS2: ERG fusions. In addition, 16 fusions were detected only in the DNA data, as RNA could not be sequenced, including 13 TMPRSS2: ERG fusions. Conclusions: In addition to TMPRSS2: ERG, the Oncomap ExTra assay identified several low frequency ETS fusions, all of which could be used to assist patients and physicians to select appropriate treatments. The identification of ETS fusions appears to be limited when using only DNA sequencing. Oncomap ExTra RNA analysis identified 66 additional fusions, representing almost 30% of those present, not identified by whole-exome DNA sequencing, suggesting RNA plus DNA assays detect fusions more reliably than DNA-only assays.

Allosteric inhibition of HSP70 in collaboration with STUB1 augments enzalutamide efficacy in antiandrogen resistant prostate tumor and patient-derived models

Ubiquitin proteasome activity is suppressed in enzalutamide resistant prostate cancer cells, and the heat shock protein 70/STIP1 homology and U-box-containing protein 1 (HSP70/STUB1) machinery are involved in androgen receptor (AR) and AR variant protein stabilization. Targeting HSP70 could be a viable strategy to overcome resistance to androgen receptor signaling inhibitor (ARSI) in advanced prostate cancer. Here, we showed that a novel HSP70 allosteric inhibitor, JG98, significantly suppressed drug-resistant C4–2B MDVR and CWR22Rv1 cell growth, and enhanced enzalutamide treatment. JG98 also suppressed cell growth in conditional reprogramed cell cultures (CRCs) and organoids derived from advanced prostate cancer patient samples. Mechanistically, JG98 degraded AR/AR-V7 expression in resistant cells and promoted STUB1 nuclear translocation to bind AR-V7. Knockdown of the E3 ligase STUB1 significantly diminished the anticancer effects and partially restored AR-V7 inhibitory effects of JG98. JG231, a more potent analog developed from JG98, effectively suppressed the growth of the drug-resistant prostate cancer cells, CRCs, and organoids. Notably, the combination of JG231 and enzalutamide synergistically inhibited AR/AR-V7 expression and suppressed CWR22Rv1 xenograft tumor growth. Inhibition of HSP70 using novel small-molecule inhibitors coordinates with STUB1 to regulate AR/AR-V7 protein stabilization and ARSI resistance.

Advantages and limitations of 3D organoids and ex vivo tumor tissue culture in personalized medicine for prostate cancer.

Current in vitro model systems do not fully reflect the bio-logical and clinical diversity of prostate cancer (PCa). Organoids are 3D in vitro cell cultures that may better recapitulate disease heterogeneity and retain parental tumor characteristics. Short-term ex vivo culture of PCa tissues may also facilitate drug testing in personalized medicine. For organoid culture, we have processed both cancer and normal tissues from 50 patients who underwent radical prostatectomy or transurethral resection of the prostate. In addition, we exploited the ex vivo tissue culture technique and performed short-term chemotherapy assay using gemcitabine and Chk1 inhibitor MU380 in 10 patient samples. In total, we were able to cultivate organoids from 58% of tumors (29/50) and 69% of normal tissue (20/29). Immunohistochemical staining of two representative cases revealed cell positivity for pan-cytokeratin confirming the presence of epithelial cells. However, the overexpression of AMACR and ERG proteins in tumors was not recapitulated in organoids. Another limitation was the propagation of organoids only up to 3 weeks till the first passage. Next, a short-term drug test was performed for ten patients using ex vivo tissue culture. Samples from prostatectomies mostly presented a low proliferation rate as assessed by Ki-67 staining. Another drawback of this ap-proach was inconsistent tissue morphology among particular tissue fragments. Only one case showed a high proliferation rate for drug testing and tumor tissue was present in all tested samples. In our work, we also provide an overview of recent studies and a detailed comparison of culture conditions. We have established cultures of both organoids and tissue fragments from PCa patient samples. However, the expression of tumor markers was not recapitulated in organoids. Inconsistent morphology among tissue fragments and low proliferation hampered the interpretation of the drug testing in most cases. Still, these approaches may be promising using tissues from metastatic castration-resistant prostate cancer.

Retinoblastoma protein as an intrinsic BRD4 inhibitor modulates small molecule BET inhibitor sensitivity in cancer

Bromodomain and extraterminal (BET) proteins including BRD4 play important roles in oncogenesis and immune inflammation. Here we demonstrate that cancer cells with loss of the retinoblastoma (RB) tumor suppressor became resistant to small molecule bromodomain inhibitors of BET proteins. We find that RB binds to bromodomain-1 (BD1) of BRD4, but binding is impeded by CDK4/6-mediated RB phosphorylation at serine-249/threonine-252 (S249/T252). ChIP-seq analysis shows RB knockdown increases BRD4 occupancy at genomic loci of genes enriched in cancer-related pathways including the GPCR-GNBIL-CREB axis. S249/T252-phosphorylated RB positively correlates with GNBIL protein level in prostate cancer patient samples. BET inhibitor resistance in RB-deficient cells is abolished by co-administration of CREB inhibitor. Our study identifies RB protein as a bona fide intrinsic inhibitor of BRD4 and demonstrates that RB inactivation confers resistance to small molecule BET inhibitors, thereby revealing a regulatory hub that converges RB upstream signaling onto BRD4 functions in diseases such as cancer.

The METTL3 RNA Methyltransferase Regulates Transcriptional Networks in Prostate Cancer.

Simple SummaryProstate cancer is driven by androgen receptor-regulated transcription and is a leading cause of cancer deaths. For this reason, androgen deprivation therapies are commonly used to treat advanced prostate cancer. These treatments are often effective for short durations before the emergence of treatment resistance and disease progression to castrate resistant prostate cancer or neuroendocrine-like disease. The aim of this study was to address whether new therapies targeting the epitranscriptome may suppress androgen signalling and thus represent a novel approach to prostate cancer treatment.Prostate cancer (PCa) is a leading cause of cancer-related deaths and is driven by aberrant androgen receptor (AR) signalling. For this reason, androgen deprivation therapies (ADTs) that suppress androgen-induced PCa progression either by preventing androgen biosynthesis or via AR signalling inhibition (ARSi) are common treatments. The N6-methyladenosine (m6A) RNA modification is involved in regulating mRNA expression, translation, and alternative splicing, and through these mechanisms has been implicated in cancer development and progression. RNA-m6A is dynamically regulated by the METTL3 RNA methyltransferase complex and the FTO and ALKBH5 demethylases. While there is evidence supporting a role for aberrant METTL3 in many cancer types, including localised PCa, the wider contribution of METTL3, and by inference m6A, in androgen signalling in PCa remains poorly understood. Therefore, the aim of this study was to investigate the expression of METTL3 in PCa patients and study the clinical and functional relevance of METTL3 in PCa. It was found that METTL3 is aberrantly expressed in PCa patient samples and that siRNA-mediated METTL3 knockdown or METTL3-pharmacological inhibition significantly alters the basal and androgen-regulated transcriptome in PCa, which supports targeting m6A as a novel approach to modulate androgen signalling in PCa.

JAZF1: A Metabolic Regulator of Sensitivity to a Polyamine-Targeted Therapy.

We have shown JAZF1 can alter sensitivity of cells and its expression can segregate patient populations into those that do, or do not highly express polyamine genes, leading to better prediction of response to a polyamine targeting therapy.

Homing in on a Moving Target: Androgen Receptor Cistromic Plasticity in Prostate Cancer.

The androgen receptor (AR) is the critical driver in prostate cancer and exerts its function mainly through transcriptional control. Recent advances in clinical studies and cell line models have illustrated that AR chromatin binding features are not static; rather they are highly variable yet reproducibly altered between clinical stages. Extensive genomic analyses of AR chromatin binding features in different disease stages have revealed a high degree of plasticity of AR chromatin interactions in clinical samples. Mechanistically, AR chromatin binding patterns are associated with specific somatic mutations on AR and other permutations, including mutations of AR-interacting proteins. Here we summarize the most recent studies on how the AR cistrome is dynamically altered in prostate cancer models and patient samples, and what implications this has for the identification of therapeutic targets to avoid the emergence of treatment resistance.

GCN2 eIF2 kinase promotes prostate cancer by maintaining amino acid homeostasis.

A stress adaptation pathway termed the integrated stress response has been suggested to be active in many cancers including prostate cancer (PCa). Here, we demonstrate that the eIF2 kinase GCN2 is required for sustained growth in androgen-sensitive and castration-resistant models of PCa both in vitro and in vivo, and is active in PCa patient samples. Using RNA-seq transcriptome analysis and a CRISPR-based phenotypic screen, GCN2 was shown to regulate expression of over 60 solute-carrier (SLC) genes, including those involved in amino acid transport and loss of GCN2 function reduces amino acid import and levels. Addition of essential amino acids or expression of 4F2 (SLC3A2) partially restored growth following loss of GCN2, suggesting that GCN2 targeting of SLC transporters is required for amino acid homeostasis needed to sustain tumor growth. A small molecule inhibitor of GCN2 showed robust in vivo efficacy in androgen-sensitive and castration-resistant mouse models of PCa, supporting its therapeutic potential for the treatment of PCa.