Therapy-resistant Prostate Cancer Research Articles

Harnessing transcriptionally driven chromosomal instability adaptation to target therapy-refractory lethal prostate cancer

Metastatic prostate cancer (PCa) inevitably acquires resistance to standard therapy preceding lethality. Here, we unveil a chromosomal instability (CIN) tolerance mechanism as a therapeutic vulnerability of therapy-refractory lethal PCa. Through genomic and transcriptomic analysis of patient datasets, we find that castration and chemotherapy-resistant tumors display the highest CIN and mitotic kinase levels. Functional genomics screening coupled with quantitative phosphoproteomics identify MASTL kinase as a survival vulnerability specific of chemotherapy-resistant PCa cells. Mechanistically, MASTL upregulation is driven by transcriptional rewiring mechanisms involving the non-canonical transcription factors androgen receptor splice variant 7 and E2F7 in a circuitry that restrains deleterious CIN and prevents cell death selectively in metastatic therapy-resistant PCa cells. Notably, MASTL pharmacological inhibition re-sensitizes tumors to standard therapy and improves survival of pre-clinical models. These results uncover a targetable mechanism promoting high CIN adaptation and survival of lethal PCa.

The role of glutamine metabolism in castration-resistant prostate cancer.

Reprogramming of metabolism is a hallmark of tumors, which has been explored for therapeutic purposes. Prostate cancer (PCa), particularly advanced and therapy-resistant PCa, displays unique metabolic properties. Targeting metabolic vulnerabilities in PCa may benefit patients who have exhausted currently available treatment options and improve clinical outcomes. Among the many nutrients, glutamine has been shown to play a central role in the metabolic reprogramming of advanced PCa. In addition to amino acid metabolism, glutamine is also widely involved in the synthesis of other macromolecules and biomasses. Targeting glutamine metabolic network by maximally inhibiting glutamine utilization in tumor cells may significantly add to treatment options for many patients. This review summarizes the metabolic landscape of PCa, with a particular focus on recent studies of how glutamine metabolism alterations affect therapeutic resistance and disease progression of PCa, and suggests novel therapeutic strategies.

Small ankyrin 1 (sANK1) promotes docetaxel resistance in castration-resistant prostate cancer cells by enhancing oxidative phosphorylation.

Docetaxel (DTX) plays an important role in treating advanced prostate cancer (PCa). However, nearly all patients receiving DTX therapy ultimately progress to DTX resistance. How to address DTX resistance in PCa remains a key challenge for all urologists. Small ankyrin 1 (sAnk1) is an integral membrane protein in the endoplasmic reticulum. In the present study, we identified that sAnk1 is upregulated in PCa tissues and is positively associated with DTX therapy resistance in PCa. Further investigation demonstrated that overexpression of sAnk1 can significantly increase the DTX-resistant ability of PCa cells in vitro and in vivo. In addition, overexpression of sAnk1 could enhance oxidative phosphorylation (OXPHOS) levels in PCa cells, which was consistent with the higher OXPHOS levels observed in DTX-resistant PCa cells as compared to DTX-sensitive PCa cells. sAnk1 was also found to interact with polypyrimidine-tract binding protein (PTBP1), an alternative splicing factor, and suppressed PTBP1-mediated alternative splicing of the pyruvate kinase gene (PKM). Thus, overexpression of sAnk1decreased the ratio of PKM2/PKM1, enhanced the OXPHOS level, and ultimately promoted the resistance of PCa cells to DTX. In summary, our data suggest that sAnk1 enhances DTX resistance in PCa cells.

Abstract A028: Investigating the epigenetic landscape of chemotherapy-induced polyaneuploid prostate cancer cells

Abstract While localized prostate cancer (PCa) has a high treatment success rate, over 30,000 individuals in the United States and 350,000 men globally die each year from therapy resistant, metastatic PCa. A thorough understanding of the factors contributing to PCa recurrence following development of therapy resistance is acutely needed in order to develop efficacious treatments and disease-management strategies. Our group and others have identified a unique minority population of physically enlarged cancer cells with polyaneuploid genomes, termed polyaneuploid cancer cells (PACCs), in the tumors of patients with metastatic prostate cancer and in other tumor types. PACCs are the result of a polyaneuploid transition that occurs when aneuploid cancer cells experience environmental or therapeutic stress. These aneuploid cancer cells then pause their cell cycle after whole genome doubling to survive the environmental insult. Cancer cells in the PACC state appear to be quiescent and have an increased capacity for invasion/motility, an ability to endure in stressful or novel environments, and a propensity to undergo depolyploidization to re-establish the cancer cell population. We hypothesize that PACCs are critical players in prostate cancer therapy resistance and recurrence. We seek to better understand the life cycle of the PACC state in PCa in order to inform the design of new therapeutic strategies that prevent disease recurrence. Our data suggests that PCa cells in the PACC state tend to have a large polyploid single nucleus more frequently than multiple smaller, single nuclei, though both are observed at all timepoints in PACC recovery. Nuclear morphology and size certainly will impact the way that a cell organizes and utilizes its genome. Additionally, genome organization and stability have been demonstrated to be important factors/drivers of cancer development, progression, and recurrence. Importantly, epigenetic changes such as histone modifications can drastically affect chromatin condensation, which subsequently can alter the gene accessibility and transcription profile of a cell. We hypothesize that cancer cells in the PACC state have different histone modifications and different regions of accessible chromatin compared to parental cancer cells, and that these differences will also impact the gene expression of PACCs. Citation Format: Anna Gonye, Chi-Ju Kim, Ken Pienta, Sarah Amend. Investigating the epigenetic landscape of chemotherapy-induced polyaneuploid prostate cancer cells. [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 A028.

Lin28 Regulates Cancer Cell Stemness for Tumour Progression.

Simple SummaryCancer stem cells (CSCs) are a small population of tumour cells bearing stemness characteristics. They have been deemed as a root of cancer development and a promising drug target for anticancer therapy. Herein, we discuss the roles of an RNA-binding protein, Lin28, in regulating cancer cell stemness to drive tumour progression. Lin28 acts on various types of RNAs in cancer cells and regulates these RNA functions to control the expression of oncogenes. In these ways, Lin28 promotes cancer cell survival, growth, and invasion. We also discuss recent efforts in developing Lin28 inhibitors targeting CSCs in tumours.Tumours develop therapy resistance through complex mechanisms, one of which is that cancer stem cell (CSC) populations within the tumours present self-renewable capability and phenotypical plasticity to endure therapy-induced stress conditions and allow tumour progression to the therapy-resistant state. Developing therapeutic strategies to cope with CSCs requires a thorough understanding of the critical drivers and molecular mechanisms underlying the aforementioned processes. One such hub regulator of stemness is Lin28, an RNA-binding protein. Lin28 blocks the synthesis of let-7, a tumour-suppressor microRNA, and acts as a global regulator of cell differentiation and proliferation. Lin28also targets messenger RNAs and regulates protein translation. In this review, we explain the role of the Lin28/let-7 axis in establishing stemness, epithelial-to-mesenchymal transition, and glucose metabolism reprogramming. We also highlight the role of Lin28 in therapy-resistant prostate cancer progression and discuss the emergence of Lin28-targeted therapeutics and screening methods.

Role of lupeol in chemosensitizing therapy-resistant prostate cancer cells by targeting MYC, β-catenin and c-FLIP: in silico and in vitro studies.

Role of lupeol in chemosensitizing therapy-resistant prostate cancer cells by targeting MYC, β-catenin and c-FLIP: in silico and in vitro studies.

Ectopic JAK–STAT activation enables the transition to a stem-like and multilineage state conferring AR-targeted therapy resistance

Emerging evidence indicates that various cancers can gain resistance to targeted therapies by acquiring lineage plasticity. Although various genomic and transcriptomic aberrations correlate with lineage plasticity, the molecular mechanisms enabling the acquisition of lineage plasticity have not been fully elucidated. We reveal that Janus kinase (JAK)–signal transducer and activator of transcription (STAT) signaling is a crucial executor in promoting lineage plasticity-driven androgen receptor (AR)-targeted therapy resistance in prostate cancer. Importantly, ectopic JAK–STAT activation is specifically required for the resistance of stem-like subclones expressing multilineage transcriptional programs but not subclones exclusively expressing the neuroendocrine-like lineage program. Both genetic and pharmaceutical inhibition of JAK–STAT signaling resensitizes resistant tumors to AR-targeted therapy. Together, these results suggest that JAK–STAT are compelling therapeutic targets for overcoming lineage plasticity-driven AR-targeted therapy resistance.

Pro-Survival Factor EDEM3 Confers Therapy Resistance in Prostate Cancer.

Prostate cancer is the most common cancer in men, and it is primarily driven by androgen steroid hormones. The glycosylation enzyme EDEM3 is controlled by androgen signalling and is important for prostate cancer viability. EDEM3 is a mannosidase that trims mannose from mis-folded glycoproteins, tagging them for degradation through endoplasmic reticulum-associated degradation. Here, we find that EDEM3 is upregulated in prostate cancer, and this is linked to poorer disease-free survival. Depletion of EDEM3 from prostate cancer cells induces an ER stress transcriptomic signature, and EDEM3 overexpression is cyto-protective against ER stressors. EDEM3 expression also positively correlates with genes involved in the unfolded protein response in prostate cancer patients, and its expression can be induced through exposure to radiation. Importantly, the overexpression of EDEM3 promotes radio-resistance in prostate cancer cells and radio-resistance can be reduced through depletion of EDEM3. Our data thus implicate increased levels of EDEM3 with a role in prostate cancer pathology and reveal a new therapeutic opportunity to sensitise prostate tumours to radiotherapy.

The Immunotherapy and Immunosuppressive Signaling in Therapy-Resistant Prostate Cancer.

Prostate cancer is one of the most common malignant tumors in men. Initially, it is androgen-dependent, but it eventually develops into castration-resistant prostate cancer (CRPC), which is incurable with current androgen receptor signaling target therapy and chemotherapy. Immunotherapy, specifically with immune checkpoint inhibitors, has brought hope for the treatment of this type of prostate cancer. Approaches such as vaccines, adoptive chimeric antigen receptor-T (CAR-T) cells, and immune checkpoint inhibitors have been employed to activate innate and adaptive immune responses to treat prostate cancer, but with limited success. Only Sipuleucel-T and the immune checkpoint inhibitor pembrolizumab are approved by the US FDA for the treatment of limited prostate cancer patients. Prostate cancer has a complex tumor microenvironment (TME) in which various immunosuppressive molecules and mechanisms coexist and interact. Additionally, prostate cancer is considered a “cold” tumor with low levels of tumor mutational burden, low amounts of antigen-presenting and cytotoxic T-cell activation, and high levels of immunosuppressive molecules including cytokines/chemokines. Thus, understanding the mechanisms of immunosuppressive signaling activation and immune evasion will help develop more effective treatments for prostate cancer. The purpose of this review is to summarize emerging advances in prostate cancer immunotherapy, with a particular focus on the molecular mechanisms that lead to immune evasion in prostate cancer. At the same time, we also highlight some potential therapeutic targets to provide a theoretical basis for the treatment of prostate cancer.

Interferon signalling contributes to therapy‐resistant prostate cancer progression

Interferon signalling contributes to therapy‐resistant prostate cancer progression

Abstract 140: Polyaneuploid prostate cancer cells induced via chemotherapy have predominantly large, single nuclei

Abstract While localized prostate cancer (PCa) has a high treatment success rate, over 30,000 individuals in the United States and 350,000 men globally die each year from therapy resistant, metastatic PCa. A thorough understanding of the factors contributing to PCa recurrence following development of therapy resistance is acutely needed in order to develop efficacious treatments and disease-management strategies.Our group and others have identified a unique minority population of physically enlarged cancer cells with polyaneuploid genomes, termed polyaneuploid cancer cells (PACCs), in the tumors of patients with metastatic prostate cancer and in other tumor types. PACCs are the result of a polyaneuploid transition that occurs when aneuploid cancer cells experience environmental or therapeutic stress. These aneuploid cancer cells then pause their cell cycle after whole genome doubling to survive the environmental insult. Cancer cells in the PACC state appear to be quiescent and have an increased capacity for invasion/motility, an ability to endure in stressful or novel environments, and a propensity to undergo depolyploidization to re-establish the cancer cell population. We hypothesize that PACCs are critical players in prostate cancer therapy resistance and recurrence. We seek to better understand the life cycle of the PACC state in PCa in order to inform the design of new therapeutic strategies that prevent disease recurrence.One important part of understanding how cells enter and exit that PACC state is to characterize the features of the PACC nuclei compared to “typical” PCa cells. Examining the distribution of DNA content and the size of individual nuclei allows us to infer the underlying mechanisms PCa cells use to enter the PACC state, such as cell fusion, endomitosis, endocycling, or mitotic slippage. Nuclear structure can further indicate what types of depolyploidization are possible, including neosis, polyploid mitosis, or uneven cell division. Thus, we developed a robust method to isolate nuclei from PACCs and used flow cytometry and immunofluorescence imaging to ascertain the nuclear content and size from whole PACC cells as well as the isolated nuclei. Analysis of nuclear features from both whole cells and isolated nuclei is necessary to resolve truly multinucleated cells from those that contain a single polylobulated nucleus.Our preliminary data suggests that PCa cells in the PACC state tend to have a large polyploid single nucleus more frequently than multiple smaller, single nuclei, though both were observed. This is in contrast with the opinion of many in the field, who believe that PACCs (and other variations of giant polyploid cancer cells) only exist in a multinucleated state. Continuation of these studies in various cancer cell lines and at sequential timepoints in the PACC state will deepen our understanding of how cancer cells evade systemic treatment and cause disease recurrence. Citation Format: Anna Gonye, Chi-Ju Kim, Kenneth Pienta, Sarah Amend. Polyaneuploid prostate cancer cells induced via chemotherapy have predominantly large, single nuclei [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 140.

From Therapy Resistance to Targeted Therapies in Prostate Cancer

Prostate cancer (PCa) is the second most common malignancy among men worldwide. Although early-stage disease is curable, advanced stage PCa is mostly incurable and eventually becomes resistant to standard therapeutic options. Different genetic and epigenetic alterations are associated with the development of therapy resistant PCa, with specific players being particularly involved in this process. Therefore, identification and targeting of these molecules with selective inhibitors might result in anti-tumoral effects. Herein, we describe the mechanisms underlying therapy resistance in PCa, focusing on the most relevant molecules, aiming to enlighten the current state of targeted therapies in PCa. We suggest that selective drug targeting, either alone or in combination with standard treatment options, might improve therapeutic sensitivity of resistant PCa. Moreover, an individualized analysis of tumor biology in each PCa patient might improve treatment selection and therapeutic response, enabling better disease management.

Hypoxia-Reoxygenation Couples 3βHSD1 Enzyme and Cofactor Upregulation to Facilitate Androgen Biosynthesis and Hormone Therapy Resistance in Prostate Cancer.

Hypoxia followed by reoxygenation in prostate cancer drives androgen deprivation therapy resistance via increasing the rate-limiting enzyme and cofactors for androgen synthesis, revealing HIF2α as a therapeutic target to subvert resistance.

Androgen receptor splice variant-7 in breast cancer: clinical and pathologic correlations

Androgen receptor (AR) inhibitor therapy is a developing treatment for AR-positive breast cancer (BC) with ongoing clinical trials. AR splice variant-7 (AR-V7) is a truncated variant of AR that leads to AR inhibitor therapy resistance in prostate cancer; recent studies have identified AR-V7 in BC and theorized that AR-V7 can have a similar impact. This study assessed the prevalence and clinicopathologic features associated with AR-V7 in a large BC cohort. BC samples were evaluated by MSK-Fusion targeted RNAseq for AR-V7 detection and MSK-IMPACT targeted DNAseq, including triple-negative tumors with no driver alteration and estrogen receptor-positive/ESR1 wildtype tumors progressing on therapy. Among 196 primary and metastatic/recurrent cases (196 RNAseq, 194DNAseq), 9.7% (19/196) were AR-V7 positive and 90.3% (177/196) AR-V7 negative. All AR-V7 positive BC were AR-positive by immunohistochemistry (19/19). The prevalence of AR-V7 by receptor subtype (N = 189) was: 18% (12/67) in ER-/PgR-/HER2-negative BC, 3.7% (4/109) in ER-positive/HER2-negative BC, and 15.4% (2/13) in HER2-positive BC; AR-V7 was detected in one ER-positive/HER2-unknown BC. Apocrine morphology was observed in 42.1% (8/19) of AR-V7 positive BC and 3.4% (6/177) AR-V7 negative BC (P < 0.00001). Notably, AR-V7 was detected in 2 primary BC and 7 metastatic/recurrent BC patients with no prior endocrine therapy. We conclude that positive AR IHC and apocrine morphology are pathologic features that may indicate testing for AR-V7 is warranted in both primary and metastatic BC in the appropriate clinical context. The study findings further encourage the assessment of AR-V7 as a predictive biomarker for AR antagonist benefit in ongoing clinical BC trials.

SOX2 mediates metabolic reprogramming of prostate cancer cells.

New strategies are needed to predict and overcome metastatic progression and therapy resistance in prostate cancer. One potential clinical target is the stem cell transcription factor SOX2, which has a critical role in prostate development and cancer. We thus investigated the impact of SOX2 expression on patient outcomes and its function within prostate cancer cells. Analyses of SOX2 expression among a case-control cohort of 1028 annotated tumor specimens demonstrated that SOX2 expression confers a more rapid time to metastasis and decreased patient survival after biochemical recurrence. SOX2 ChIP-Seq analyses revealed SOX2 binding sites within prostate cancer cells which differ significantly from canonical embryonic SOX2 gene targets, and prostate-specific SOX2 gene targets are associated with multiple oncogenic pathways. Interestingly, phenotypic and gene expression analyses after CRISPR-mediated deletion of SOX2 in castration-resistant prostate cancer cells, as well as ectopic SOX2 expression in androgen-sensitive prostate cancer cells, demonstrated that SOX2 promotes changes in multiple metabolic pathways and metabolites. SOX2 expression in prostate cancer cell lines confers increased glycolysis and glycolytic capacity, as well as increased basal and maximal oxidative respiration and increased spare respiratory capacity. Further, SOX2 expression was associated with increased quantities of mitochondria, and metabolomic analyses revealed SOX2-associated changes in the metabolism of purines, pyrimidines, amino acids and sugars, and the pentose phosphate pathway. Analyses of SOX2 gene targets with central functions metabolism (CERK, ECHS1, HS6SDT1, LPCAT4, PFKP, SLC16A3, SLC46A1, and TST) document significant expression correlation with SOX2 among RNA-Seq datasets derived from patient tumors and metastases. These data support a key role for SOX2 in metabolic reprogramming of prostate cancer cells and reveal new mechanisms to understand how SOX2 enables metastatic progression, lineage plasticity, and therapy resistance. Further, our data suggest clinical opportunities to exploit SOX2 as a biomarker for staging and imaging, as well as a potential pharmacologic target.

Targeting glutamine metabolism network for the treatment of therapy-resistant prostate cancer.

Advanced and aggressive prostate cancer (PCa) depends on glutamine for survival and proliferation. We have previously shown that inhibition of glutaminase 1, which catalyzes the rate-limiting step of glutamine catabolism, achieves significant therapeutic effect; however, therapy resistance is inevitable. Here we report that while the glutamine carbon is critical to PCa survival, a parallel pathway of glutamine nitrogen catabolism that actively contributes to pyrimidine assembly is equally important for PCa cells. Importantly, we demonstrate a reciprocal feedback mechanism between glutamine carbon and nitrogen pathways which leads to therapy resistance when one of the two pathways is inhibited. Combination treatment to inhibit both pathways simultaneously yields better clinical outcome for advanced PCa patients.

THEM6‐mediated reprogramming of lipid metabolism supports treatment resistance in prostate cancer

Despite the clinical benefit of androgen‐deprivation therapy (ADT), the majority of patients with advanced prostate cancer (PCa) ultimately develop lethal castration‐resistant prostate cancer (CRPC). In this study, we identified thioesterase superfamily member 6 (THEM6) as a marker of ADT resistance in PCa. THEM6 deletion reduces in vivo tumour growth and restores castration sensitivity in orthograft models of CRPC. Mechanistically, we show that the ER membrane‐associated protein THEM6 regulates intracellular levels of ether lipids and is essential to trigger the induction of the ER stress response (UPR). Consequently, THEM6 loss in CRPC cells significantly alters ER function, reducing de novo sterol biosynthesis and preventing lipid‐mediated activation of ATF4. Finally, we demonstrate that high THEM6 expression is associated with poor survival and correlates with high levels of UPR activation in PCa patients. Altogether, our results highlight THEM6 as a novel driver of therapy resistance in PCa as well as a promising target for the treatment of CRPC.

PDZRN4 suppresses tumorigenesis and androgen therapy-resistance in prostate cancer.

Background: PDZRN4 (PDZ domain-containing RING finger 4), a member of the LNX (ligand of numb protein-X) family that regulates the levels of NUMB, plays a critical role in suppressing the proliferation and invasion of hormone-related malignant tumours. There are few studies on the role of PDZRN4 in the pathogenesis of prostate cancer (PCa). We aimed to examine whether PDZRN4 regulates the growth and development of PCa.Methods: Cell transduction and Western blotting were used to establish and confirm PDZRN4 knock down in PC cells. Using the MTT, wound healing, transwell migration, and animal experiments, we explored the biological function of PDZRN4 knockdown (PDZRN4-kd) cells. Via PCR and immunohistochemistry, the mRNA and protein expression of PDZRN4 was examined in PC cells and tissues.Results: Hormone-dependent (LNCap) and hormone-independent (DU145, PC3, and C4-2) PC lines were transfected with lentivirus carrying PDZRN4 shRNA. The Western blotting results showed that the expression of PDZRN4 was stably downregulated in PDZRN4 knockdown (PDZRN4-kd) cells. The proliferation, invasion and migration of PDZRN4-kd cells were dramatically increased in vivo. To explore the expression of PDZRN4 in prostate cancer samples, we analysed TCGA data and found that PDZRN4 was negatively correlated with the development of PC. PDZRN4 levels were downregulated by androgen deprivation in hormone-sensitive cells. Moreover, PDZRN4 failed to induce proliferation in DU145 cells with androgen deprivation.Conclusions: PDZRN4 is a functional suppressor of prostate cancer growth and development and is a potential target of biochemical therapy in hormone-resistant PC.

Alterations in BRCA2 as Determinants of Therapy Response in Prostate Cancer.

Prostate cancer (PCa) is one of the leading causes of cancer diagnoses and cancer-related deaths in the United States. Mutations or deletions in the genes involved in the DNA damage response (DDR) are common in aggressive primary PCa (germline alterations) and further enriched in advanced therapy-resistant PCa (somatic alterations). Among the DDR genes, BRCA2 is the most commonly altered (~ 13%) in advanced therapy-resistant PCa. Patients with BRCA2-altered PCas are exquisitely sensitive to poly (ADP-ribose) polymerase (PARP) inhibitors (PARPis). Indeed, two PARPis-olaparib and rucaparib have recently gained U.S. Food & Drug Administration approval for the treatment of advanced PCas harboring a BRCA2 mutation. This review seeks to explore the role of BRCA2 in DNA damage repair, the pathogenesis and progression of BRCA2 mutant PCa, and the utility of radiation therapy, targeted therapies, and platinum-based chemotherapies for patients with BRCA2 alterations.

MP33-17 A GLUTAMINASE ISOFORM SWITCH DRIVES THERAPEUTIC RESISTANCE AND DISEASE PROGRESSION OF PROSTATE CANCER

You have accessJournal of UrologyProstate Cancer: Basic Research & Pathophysiology I (MP33)1 Sep 2021MP33-17 A GLUTAMINASE ISOFORM SWITCH DRIVES THERAPEUTIC RESISTANCE AND DISEASE PROGRESSION OF PROSTATE CANCER Lingfan Xu Lingfan XuLingfan Xu More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002042.17AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Prostate cancer is one of the most common cancer type in men. Although hormonal therapy, which targets the androgen receptor (AR) signaling, is efficacious initially, tumor recurrence will eventually recur. Better understanding the mechanism of therapy resistance and disease progression and therefore exploiting new therapeutic target is a pressing unmet issue. METHODS: We employed mass spectrometry and isotopomer tracing technology to determine metabolic flux and reprogramming in different stage of prostate cancer (primary, castration-resistant and neuroendocrine- transdifferentiated). Immunohistochemical staining on human tissue microarrays was used to determine the expression of the two isoforms of glutaminase (GLS1) across a panel of tissues diagnosed with different histology results. Genetic (e.g short hairpin RNA, crispr/cas9) and pharmacological (GLS1 inhibitor, CB-839) inhibition were employed to assess the biological function of GLS1 as well as its two splicing variants in prostate cancer. Animal models were established to longitudinally simulate the nature history of disease progression and drug therapeutic outcomes were also evaluated in vivo. RESULTS: We observe that hormonal therapy-resistant prostate cancer (including castration-resistant prostate cancer, CRPC and neuroendocrine prostate cancer, NEPC) is extremely addicted to glutamine instead of androgen, which results in the failure of AR-directed therapies. Furthermore, GLS1, the key enzyme for the glutamine metabolism, has two functionally different splicing variants (KGA and GAC), which are differentially expressed primary and recurrent stage of prostate cancer. KGA is the dominant isoform in hormone-sensitive prostate cancer whereas GAC, the much more enzymatically potent isoform, predominates in CRPC and NEPC. Furthermore, this isoform switch of GLS1 is evidently observed longitudinally in animal models along with tumor recurrence after being castrated. GLS1 selective inhibitor, CB-839, shows great inhibitory effect preferentially on GAC-dominant prostate cancer variants. CONCLUSIONS: An isoform switch of GLS1, from KGA to GAC, drives prostate cancer to be resistant to hormonal therapy, but dependent on glutamine due to the hyper capability of GAC for glutamine utilization. Therefore, GAC would be an ideal target independently of AR for those androgen/AR-indifferent prostate cancer patients. Source of Funding: None © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e613-e613 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Lingfan Xu More articles by this author Expand All Advertisement Loading ...