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The mechanisms underlying ETS -driven prostate cancer initiation and progression remain poorly understood due to a lack of model systems that recapitulate this phenotype. We generated a genetically engineered mouse with prostate-specific expression of the ETS factor, ETV4, at lower and higher protein dosage through mutation of its degron. Lower-level expression of ETV4 caused mild luminal cell expansion without histologic abnormalities, and higher-level expression of stabilized ETV4 caused prostatic intraepithelial neoplasia (mPIN) with 100% penetrance within 1 week. Tumor progression was limited by p53-mediated senescence and Trp53 deletion cooperated with stabilized ETV4. The neoplastic cells expressed differentiation markers such as Nkx3.1 recapitulating luminal gene expression features of untreated human prostate cancer. Single-cell and bulk RNA sequencing showed that stabilized ETV4 induced a previously unidentified luminal-derived expression cluster with signatures of cell cycle, senescence, and epithelial-to-mesenchymal transition. These data suggest that ETS overexpression alone, at sufficient dosage, can initiate prostate neoplasia.

Supplemental Figure Legends

Direct comparison of various BET inhibitors in prostate cancer cells.

De-recruitment of BRD2/3/4 from the SRSF1 and U2AF1 promoter by JQ1.

Supplemental Materials and Methods

Antibodies and PCR Primers

AR- and ERG-positive PDX model displays sensitivity to JQ1.

Enzalutamide resistant VCaP prostate cancer cells.

No curative therapy is currently available for metastatic prostate cancer (PCa). The diverse mechanisms of progression include fibroblast growth factor (FGF) axis activation.To investigate the molecular and clinical implications of fibroblast growth factor receptor 1 (FGFR1) and its isoforms (α/β) in the pathogenesis of PCa bone metastases.In silico, in vitro, and in vivo preclinical approaches were used. RNA-sequencing and immunohistochemical (IHC) studies in human samples were conducted.In mice, bone metastases (chi-square/Fisher's test) and survival (Mantel-Cox) were assessed. In human samples, FGFR1 and ladinin 1 (LAD1) analysis associated with PCa progression were evaluated (IHC studies, Fisher's test).FGFR1 isoform expression varied among PCa subtypes. Intracardiac injection of mice with FGFR1-expressing PC3 cells reduced mouse survival (α, p 0.0001; β, p = 0.032) and increased the incidence of bone metastases (α, p 0.0001; β, p = 0.02). Accordingly, IHC studies of human castration-resistant PCa (CRPC) bone metastases revealed significant enrichment of FGFR1 expression compared with treatment-naïve, nonmetastatic primary tumors (p = 0.0007). Expression of anchoring filament protein LAD1 increased in FGFR1-expressing PC3 cells and was enriched in human CRPC bone metastases (p = 0.005).FGFR1 expression induces bone metastases experimentally and is significantly enriched in human CRPC bone metastases, supporting its prometastatic effect in PCa. LAD1 expression, found in the prometastatic PCa cells expressing FGFR1, was also enriched in CRPC bone metastases. Our studies support and provide a roadmap for the development of FGFR blockade for advanced PCa.We studied the role of fibroblast growth factor receptor 1 (FGFR1) in prostate cancer (PCa) progression. We found that PCa cells with high FGFR1 expression increase metastases and that FGFR1 expression is increased in human PCa bone metastases, and identified genes that could participate in the metastases induced by FGFR1. These studies will help pinpoint PCa patients who use fibroblast growth factor to progress and will benefit by the inhibition of this pathway.

PDF file - 1.1MB, A, Chromosomal regions commonly amplified (red) and deleted (blue) in the SCPC/LCNEC (left panel) and adenocarcinoma (AdCa, right panel) xenografts. B, AR, cyclin D1, and RB1 promoter methylation of the AR-positive LNCaP prostate cancer cell line, the AR-negative PC-3 and DU145 prostate cancer cell lines, and the SCPC/LCNEC MDA PCa 144-4, 144-13, 146-10, and 155-2 xenografts. SCPC, small-cell prostate carcinoma; LCNEC, large-cell neuroendocrine carcinoma; AR, androgen receptor; RB, retinoblastoma.

Purpose: To study Wnt/β-catenin in castrate-resistant prostate cancer (CRPC) and understand its function independently of the β-catenin–androgen receptor (AR) interaction.Experimental Design: We carried out β-catenin immunocytochemical analysis, evaluated TOP-flash reporter activity (a reporter of β-catenin–mediated transcription), and sequenced the β-catenin gene in MDA prostate cancer 118a, MDA prostate cancer 118b, MDA prostate cancer 2b, and PC-3 prostate cancer cells. We knocked down β-catenin in AR-negative MDA prostate cancer 118b cells and carried out comparative gene-array analysis. We also immunohistochemically analyzed β-catenin and AR in 27 bone metastases of human CRPCs.Results: β-Catenin nuclear accumulation and TOP-flash reporter activity were high in MDA prostate cancer 118b but not in MDA prostate cancer 2b or PC-3 cells. MDA prostate cancer 118a and MDA prostate cancer 118b cells carry a mutated β-catenin at codon 32 (D32G). Ten genes were expressed differently (false discovery rate, 0.05) in MDA prostate cancer 118b cells with downregulated β-catenin. One such gene, hyaluronan synthase 2 (HAS2), synthesizes hyaluronan, a core component of the extracellular matrix. We confirmed HAS2 upregulation in PC-3 cells transfected with D32G-mutant β-catenin. Finally, we found nuclear localization of β-catenin in 10 of 27 human tissue specimens; this localization was inversely associated with AR expression (P = 0.056, Fisher's exact test), suggesting that reduced AR expression enables Wnt/β-catenin signaling.Conclusion: We identified a previously unknown downstream target of β-catenin, HAS2, in prostate cancer, and found that high β-catenin nuclear localization and low or no AR expression may define a subpopulation of men with bone metastatic prostate cancer. These findings may guide physicians in managing these patients. Clin Cancer Res; 18(3); 726–36. ©2011 AACR.

Purpose: A hallmark of prostate cancer (PCa) progression is the development of osteoblastic bone metastases, which respond poorly to available therapies. We previously reported that VEGF121/rGel targets osteoclast precursors and tumor neovasculature. Here we tested the hypothesis that targeting nontumor cells expressing these receptors can inhibit tumor progression in a clinically relevant model of osteoblastic PCa.Experimental Design: Cells from MDA PCa 118b, a PCa xenograft obtained from a bone metastasis in a patient with castrate-resistant PCa, were injected into the femurs of mice. Osteoblastic progression was monitored following systemic administration of VEGF121/rGel.Results: VEGF121/rGel was cytotoxic in vitro to osteoblast precursor cells. This cytotoxicity was specific as VEGF121/rGel internalization into osteoblasts was VEGF121 receptor driven. Furthermore, VEGF121/rGel significantly inhibited PCa-induced bone formation in a mouse calvaria culture assay. In vivo, VEGF121/rGel significantly inhibited the osteoblastic progression of PCa cells in the femurs of nude mice. Microcomputed tomographic analysis revealed that VEGF121/rGel restored the bone volume fraction of tumor-bearing femurs to values similar to those of the contralateral (non–tumor-bearing) femurs. VEGF121/rGel significantly reduced the number of tumor-associated osteoclasts but did not change the numbers of peritumoral osteoblasts. Importantly, VEGF121/rGel-treated mice had significantly less tumor burden than control mice. Our results thus indicate that VEGF121/rGel inhibits osteoblastic tumor progression by targeting angiogenesis, osteoclastogenesis, and bone formation.Conclusions: Targeting VEGF receptor (VEGFR)-1- or VEGFR-2–expressing cells is effective in controlling the osteoblastic progression of PCa in bone. These findings provide the basis for an effective multitargeted approach for metastatic PCa. Clin Cancer Res; 17(8); 2328–38. ©2011 AACR.

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Comparison of copy number changes in MDA PCa 150 PDXs

Ranked expression of genes in MDA PCa 146-10 vs MDA PCa 146-12

Supplementary Figure S1.

PDF file - 150K, A: Mitotic figures in the xenografts; left panel: graphical presentation of the number of mitotic figures in SCPC/LCNEC xenografts (mean 11 mitoses per high power field) and adenocarcinoma xenografts (mean 2 per high power field); right panel: pictures from H&E stained slides of a SCPC and an adenocarcinoma (AdCa) xenograft. Arrows point to the mitotic figures. B: Higher expression levels of ki67 are noted in the SCPC/LCNEC xenografts and clinical samples compared to adenocarcinomas C:Flow cytometry of SCPC xenograft 146-10 and adenocarcinoma xenograft 180-30. (SCPC, small-cell prostate carcinoma; LCNEC, large-cell neuroendocrine carcinoma).

Purpose:Advances in prostate cancer lag behind other tumor types partly due to the paucity of models reflecting key milestones in prostate cancer progression. Therefore, we develop clinically relevant prostate cancer models.Experimental Design:Since 1996, we have generated clinically annotated patient-derived xenografts (PDXs; the MDA PCa PDX series) linked to specific phenotypes reflecting all aspects of clinical prostate cancer.Results:We studied two cell line–derived xenografts and the first 80 PDXs derived from 47 human prostate cancer donors. Of these, 47 PDXs derived from 22 donors are working models and can be expanded either as cell lines (MDA PCa 2a and 2b) or PDXs. The histopathologic, genomic, and molecular characteristics (androgen receptor, ERG, and PTEN loss) maintain fidelity with the human tumor and correlate with published findings. PDX growth response to mouse castration and targeted therapy illustrate their clinical utility. Comparative genomic hybridization and sequencing show significant differences in oncogenic pathways in pairs of PDXs derived from different areas of the same tumor. We also identified a recurrent focal deletion in an area that includes the speckle-type POZ protein-like (SPOPL) gene in PDXs derived from seven human donors of 28 studied (25%). SPOPL is a SPOP paralog, and SPOP mutations define a molecular subclass of prostate cancer. SPOPLdeletions are found in 7% of The Cancer Genome Atlas prostate cancers, which suggests that our cohort is a reliable platform for targeted drug development.Conclusions:The MDA PCa PDX series is a dynamic resource that captures the molecular landscape of prostate cancers progressing under novel treatments and enables optimization of prostate cancer–specific, marker-driven therapy.

PDF file - 270K, mRNA levels of A, CDC20 and B, FZR1/CDH1 in SCPC/LCNEC (MDA PCa 144-4, 144-13, 146-10, and 155-2) and adenocarcinoma (MDA PCa 170-4 and 180-30) xenografts, normalized to GAPDH. SCPC, small-cell prostate carcinoma; LCNEC, large-cell neuroendocrine carcinoma.

Supplementary Methods

Purpose:Cabozantinib, an oral inhibitor of c-MET/VEGFR2 signaling, improved progression-free survival (mPFS) but not overall survival (OS) in metastatic castrate-resistant prostate cancer. We evaluated cabozantinib plus androgen deprivation therapy (ADT) in hormone-naïve metastatic prostate cancer (HNMPCa).Patients and Methods:Patients received ADT plus cabozantinib starting at 60 mg daily. The primary endpoint was castrate-resistant PFS by radiographic criteria, clinical progression, or receipt of additional therapy. Secondary endpoints included OS, safety, radiographic responses, and biomarker modulation.Results:Sixty-two patients received treatment. With a median follow-up of 31.2 months, the mPFS was 16.1 months (95% CI, 14.6–22.7 months), and mOS was not reached. Reductions in PSA ≥ 90%, bone-specific alkaline phosphatase ≥ 50%, and urine N-telopeptides ≥ 50% occurred in 83%, 87%, and 86% of evaluable patients, respectively. Responses in bone scan and measurable disease were observed in 81% of and 90% of evaluable patients, respectively. Most common grade 3 adverse events were hypertension (19%), diarrhea (6%), and thromboembolic events (6%), and dose reductions occurred in 85% of patients. Analysis of baseline cytokine and angiogenic factors (CAFs) revealed that higher plasma concentrations of Lumican, CXCL5, CD25, and CD30 were associated with shorter PFS as was high tumor expression of pFGFR1.Conclusions:Cabozantinib plus ADT has promising clinical activity in HNMPCa. CAF profiles and tissue markers suggest candidate prognostic and predictive markers of cabozantinib benefit and provide insights for rational therapy combinations.

PDF file - 180K, A, Growth rate of MDA PCA 144-13, 146-10, 155-2, 170-4 and 180-30 xenografts. Note that the MDA PCA 144-13 xenograft line displays a large amount of necrosis. B. Diagram illustrates unsupervised hierarchal clustering using complete linkage and Pearson's correlation coefficient analysis of the raw expression profiles of androgen receptor-positive adenocarcinoma (MDA PCA 130, 117-9, 79) and androgen receptor-negative SCPC/LCNEC (MDA PCA 146-10, 155-2, 155-12, 144-13, 144-4) xenografts obtained with Affymetrix HGU133Plus2 array. In red are samples assessed on 1 day and in blue, those assessed on a different day. B, diagram illustrates Gene Ontology analysis results showing enrichment in biologic-process subtrees related to mitosis among the differently expressed genes. The biological processes that reached statistical significance are highlighted in red. SCPC, small-cell prostate carcinoma; LCNEC, large-cell neuroendocrine carcinoma.

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Purpose: Small-cell prostate carcinoma (SCPC) morphology predicts for a distinct clinical behavior, resistance to androgen ablation, and frequent but short responses to chemotherapy. We sought to develop model systems that reflect human SCPC and can improve our understanding of its biology.Experimental Design: We developed a set of castration-resistant prostate carcinomas xenografts and examined their fidelity to their human tumors of origin. We compared the expression and genomic profiles of SCPC and large-cell neuroendocrine carcinoma (LCNEC) xenografts to those of typical prostate adenocarcinoma xenografts. Results were validated immunohistochemically in a panel of 60 human tumors.Results: The reported SCPC and LCNEC xenografts retain high fidelity to their human tumors of origin and are characterized by a marked upregulation of UBE2C and other mitotic genes in the absence of androgen receptor (AR), retinoblastoma (RB1), and cyclin D1 (CCND1) expression. We confirmed these findings in a panel of samples of CRPC patients. In addition, array comparative genomic hybridization of the xenografts showed that the SCPC/LCNEC tumors display more copy number variations than the adenocarcinoma counterparts. Amplification of the UBE2C locus and microdeletions of RB1 were present in a subset, but none displayed AR nor CCND1 deletions. The AR, RB1, and CCND1 promoters showed no CpG methylation in the SCPC xenografts.Conclusion: Modeling human prostate carcinoma with xenografts allows in-depth and detailed studies of its underlying biology. The detailed clinical annotation of the donor tumors enables associations of anticipated relevance to be made. Future studies in the xenografts will address the functional significance of the findings. Clin Cancer Res; 18(3); 666–77. ©2011 AACR.

Additional Figures and Tables

Legend of Supplementary Figures

Supplementary Results

The pathophysiology of tumor growth following skeletal metastases and the poor response of this type of lesion to therapeutic intervention remains incompletely understood. Vascular endothelial growth factor (VEGF)-A and its receptors play a role in both osteoclastogenesis and tumor growth. Systemic (i.v.) treatment of nude mice bearing intrafemoral prostate (PC-3) tumors with the vascular ablative agent VEGF121/recombinant gelonin (rGel) strongly inhibited tumor growth. Fifty percent of treated animals had complete regression of bone tumors with no development of lytic bone lesions. Immunohistochemical analysis showed that VEGF121/rGel treatment suppressed tumor-mediated osteoclastogenesis in vivo. In vitro treatment of murine osteoclast precursors, both cell line (RAW264.7) and bone marrow–derived monocytes (BMM), revealed that VEGF121/rGel was selectively cytotoxic to osteoclast precursor cells rather than mature osteoclasts. VEGF121/rGel cytotoxicity was mediated by Flt-1, which was down-regulated during osteoclast differentiation. Analysis by flow cytometry and reverse transcription-PCR showed that both BMM and RAW264.7 cells display high levels of Flt-1 but low levels of Flk-1. Internalization of VEGF121/rGel into osteoclast precursor cells was suppressed by pretreatment with an Flt-1 neutralizing antibody or by placenta growth factor but not with an Flk-1 neutralizing antibody. Thus, VEGF121/rGel inhibits osteoclast maturation in vivo and it seems that this process is important in the resulting suppression of skeletal osteolytic lesions. This is a novel and unique mechanism of action for this class of agents and suggests a potentially new approach for treatment or prevention of tumor growth in bone. (Cancer Res 2006; 66(22): 10919-28)

Supplementary Figure 2 from Inhibition of Prostate Tumor Growth and Bone Remodeling by the Vascular Targeting Agent VEGF121/rGel

Supplementary Figure 1 from Inhibition of Prostate Tumor Growth and Bone Remodeling by the Vascular Targeting Agent VEGF121/rGel

Supplementary Figure 3 from Inhibition of Prostate Tumor Growth and Bone Remodeling by the Vascular Targeting Agent VEGF121/rGel

Item does not contain fulltext Patient-derived xenografts (PDXs) are generated by engrafting human tumours into mice. Serially transplantable PDXs are used to study tumour biology and test therapeutics, linking the laboratory to the clinic. Although few prostate cancer PDXs are available in large repositories, over 330 prostate cancer PDXs have been established, spanning broad clinical stages, genotypes and phenotypes. Nevertheless, more PDXs are needed to reflect patient diversity, and to study new treatments and emerging mechanisms of resistance. We can maximize the use of PDXs by exchanging models and datasets, and by depositing PDXs into biorepositories, but we must address the impediments to accessing PDXs, such as institutional, ethical and legal agreements. Through collaboration, researchers will gain greater access to PDXs representing diverse features of prostate cancer. 01 juni 2023

The switch/sucrose non-fermentable (SWI/SNF) complex has a crucial role in chromatin remodelling1 and is altered in over 20% of cancers2,3. Here we developed a proteolysis-targeting chimera (PROTAC) degrader of the SWI/SNF ATPase subunits, SMARCA2 and SMARCA4, called AU-15330. Androgen receptor (AR)+ forkhead box A1 (FOXA1)+ prostate cancer cells are exquisitely sensitive to dual SMARCA2 and SMARCA4 degradation relative to normal and other cancer cell lines. SWI/SNF ATPase degradation rapidly compacts cis-regulatory elements bound by transcription factors that drive prostate cancer cell proliferation, namely AR, FOXA1, ERG and MYC, which dislodges them from chromatin, disables their core enhancer circuitry, and abolishes the downstream oncogenic gene programs. SWI/SNF ATPase degradation also disrupts super-enhancer and promoter looping interactions that wire supra-physiologic expression of the AR, FOXA1 and MYC oncogenes themselves. AU-15330 induces potent inhibition of tumour growth in xenograft models of prostate cancer and synergizes with the AR antagonist enzalutamide, even inducing disease remission in castration-resistant prostate cancer (CRPC) models without toxicity. Thus, impeding SWI/SNF-mediated enhancer accessibility represents a promising therapeutic approach for enhancer-addicted cancers., PROTAC degrader–induced SWI/SNF inactivation abolishes DNA accessibility at enhancer elements of oncogenes and also tempers supra-physiologic expression of driver transcription factors, resulting in potent inhibition of tumour growth in mouse models.

Many advanced cancer models, such as patient-derived xenografts (PDXs), offer significant benefits in their preservation of the native tumor's heterogeneity and susceptibility to treatments, but face significant barriers to use in their reliance on a rodent host for propagation and screening. PDXs remain difficult to implement in vitro, particularly in configurations that enable both detailed cellular analysis and high-throughput screening (HTS). Complex multilineage co-cultures with stromal fibroblasts, endothelium, and other cellular and structural components of the tumor microenvironment (TME) further complicate ex vivo implementation. Herein, the culture of multiple prostate cancer (PCa)-derived PDX models as 3D clusters within engineered biomimetic hydrogel matrices, in a HTS-compatible multiwell microfluidic format, alongside bone marrow-derived stromal cells and a perfused endothelial channel. Polymeric hydrogel matrices are customized for each cell type, enabling cell survival in vitro and facile imaging across all conditions. PCa PDXs demonstrate unique morphologies and reliance on TME partners, retention of known phenotype, and expected sensitivity or resistance to standard PCa therapeutics. This novel integration of technologies provides a fully human model, and expands the information to be gathered from each specimen, while avoiding the time and labor involved with animal-based testing.

Prostate cancer (PCa) that progresses after androgen deprivation therapy (ADT) remains incurable. The underlying mechanisms that account for the ultimate emergence of resistance to ADT, progressing to castrate-resistant prostate cancer (CRPC), include those that reactivate androgen receptor (AR), or those that are entirely independent or cooperate with androgen signaling to underlie PCa progression. The intricacy of metabolic pathways associated with PCa progression spurred us to develop a metabolism-centric analysis to assess the metabolic shift occurring in PCa that progresses with low AR expression. We used PCa patient-derived xenografts (PDXs) to assess the metabolic changes after castration of tumor-bearing mice and subsequently confirmed main findings in human donor tumor that progressed after ADT. We found that relapsed tumors had a significant increase in fatty acids and ketone body (KB) content compared with baseline. We confirmed that critical ketolytic enzymes (ACAT1, OXCT1, BDH1) were dysregulated after castrate-resistant progression. Further, these enzymes are increased in the human donor tissue after progressing to ADT. In an in silico approach, increased ACAT1, OXCT1, BDH1 expression was also observed for a subset of PCa patients that relapsed with low AR and ERG (ETS-related gene) expression. Further, expression of these factors was also associated with decreased time to biochemical relapse and decreased progression-free survival. Our studies reveal the key metabolites fueling castration resistant progression in the context of a partial or complete loss of AR dependence.

Progress in understanding prostate cancer (PCa) metastasis and therapy resistance has been hampered by the lack of models, representative of the clinical spectrum and biologic complexity of the disease. Our laboratory is home to one of the largest worldwide repositories of PCa patient-derived xenografts (PDXs), the MDA PCa PDX series, a collection of clinically annotated PDXs reflecting the full spectrum of potentially lethal disease, that includes tumors that are not end stage and not castration-resistant PCa. We performed whole genome sequencing, targeted sequencing and RNA sequencing of 46 MDA PCa PDX models derived from biopsy and surgical specimens from 39 patients, selected in order to reflect the clinicopathological PCa subtypes (data available in cBioPortal). MDA PCa PDXs genomic characterization shows that the cohort recapitulates the mutational landscape found in PCa, highlighting the clinical relevance of these models. Interestingly and consistently with the clinic, certain models lack the typical PCa driver alterations, thus providing a suitable tool for discovery of novel drivers. Our cohort also includes PDXs derived from different areas of the same tumor and longitudinal samples, allowing to study disease heterogeneity and progression. Finally, we have developed a procedure to grow organoids from PDXs, thus providing a powerful in vitro platform that supports hypothesis generation, and testing of clinically relevant observations. Genomic and transcriptomic characterization of MDA PCa PDXs together with the ability to grow them as organoids for in vitro experimentation, provides a unique resource to address the existing clinical gap in PCa, helping to better understand mechanisms of response and resistance.One Sentence SummaryMDA PCa PDX series is a dynamic resource capturing the molecular landscape of prostate cancer; a platform for discovery and personalized medicine

Ductal adenocarcinoma (DAC) is the most common variant histological subtype of prostate carcinoma and has an aggressive clinical course. DAC is usually characterized and treated as high-risk prostatic acinar adenocarcinoma (PAC). However, DAC has a different biology to that of acinar disease, which often poses a challenge for both diagnosis and management. DAC can be difficult to identify using conventional diagnostic modalities such as serum PSA levels and multiparametric MRI, and the optimal management for localized DAC is unknown owing to the rarity of the disease. Following definitive therapy for localized disease with radical prostatectomy or radiotherapy, the majority of DACs recur with visceral metastases at low PSA levels. Various systemic therapies that have been shown to be effective in high-risk PAC have limited use in treating DAC. Although current understanding of the biology of DAC is limited, genomic analyses have provided insights into the pathology behind its aggressive behaviour and potential future therapeutic targets.

Purpose: Radium-223 prolongs survival in a fraction of men with bone metastatic prostate cancer (PCa). However, there are no markers for monitoring response and resistance to Radium-223 treatment. Exosomes are mediators of intercellular communication and may reflect response of the bone microenvironment to Radium-223 treatment. We performed molecular profiling of exosomes and compared the molecular profile in patients with favorable and unfavorable overall survival. Experimental Design: We performed exosomal transcriptome analysis in plasma derived from our preclinical models (MDA-PCa 118b tumors, TRAMP-C2/BMP4 PCa) and from the plasma of 25 patients (paired baseline and end of treatment) treated with Radium-223. All samples were run in duplicate, and array data analyzed with fold changes +2 to −2 and P < 0.05. Results: We utilized the preclinical models to establish that genes derived from the tumor and the tumor-associated bone microenvironment (bTME) are differentially enriched in plasma exosomes upon Radium-223 treatment. The mouse transcriptome analysis revealed changes in bone-related and DNA damage repair–related pathways. Similar findings were observed in plasma-derived exosomes from patients treated with Radium-223 detected changes. In addition, exosomal transcripts detected immune-suppressors (e.g., PD-L1) that were associated with shorter survival to Radium-223. Treatment of the Myc-CaP mouse model with a combination of Radium-223 and immune checkpoint therapy (ICT) resulted in greater efficacy than monotherapy. Conclusions: These clinical and coclinical analyses showed that RNA profiling of plasma exosomes may be used for monitoring the bTME in response to treatment and that ICT may be used to increase the efficacy of Radium-223.

Some prostate cancers (PCas) are histo-pathologically grouped within the same Gleason Grade (GG), but can differ significantly in outcome. Herein, we aimed at identifying molecular biomarkers that could improve risk prediction in PCa. LC ESI–MS/MS was performed on human PCa and benign prostatic hyperplasia (BPH) tissues and peptide data was integrated with omic analyses. We identified high YWHAZ and NDRG1 expression to be associated with poor PCa prognosis considering all Gleason scores (GS). YWHAZ and NDRG1 defined two subpopulations of PCa patients with high and intermediate risk of death. Multivariable analyses confirmed their independence from GS. ROC analysis unveiled that YWHAZ outperformed GS beyond 60 months post-diagnosis. The genomic analysis of PCa patients with YWHAZ amplification, or increased mRNA or protein levels, revealed significant alterations in key DNA repair genes. We hereby state the relevance of YWHAZ in PCa, showcasing its role as an independent strong predictor of aggressiveness., Using integrative tissue-omics, Lage-Vickers, Bizzotto et al. classify prostate cancer patients into high YWHAZ and NDRG1 expression subgroups that correlate with a high and intermediate risk of disease progression. This study identifies molecular biomarkers associated with aggressive prostate cancer.

Prostate cancer cells that survive clinical androgen receptor (AR) blockade mediate disease progression and lethality. Reprogrammed metabolic signaling is one mechanism by which tumor cells can survive treatment. However, how AR inhibition reprograms metabolism, and whether altered metabolism can be exploited to eradicate cells that survive AR blockade, remains unclear. Here, we comprehensively characterized the effect of AR blockade on prostate cancer metabolism using transcriptomics, metabolomics, and bioenergetics approaches. AR inhibition maintains oxidative mitochondrial metabolism and reduces glycolytic signaling, through hexokinase II downregulation and decreased MYC activity. Robust elongation of mitochondria via reduced DRP1 activity supports cell fitness after AR blockade. In addition, AR inhibition enhances sensitivity to complex I inhibitors in several models, suggesting that AR blockade increases reliance on oxidative mitochondrial metabolism. Our study provides an enhanced understanding of how AR inhibition alters metabolic signaling and highlights the potential of therapies that target metabolic vulnerabilities in AR-inhibited cells.

Many solid tumors metastasize to bone, but only prostate cancer has bone as a single, dominant metastatic site. Recently, the FGF axis has been implicated in cancer progression in some tumors and mounting evidence indicate that it mediates prostate cancer bone metastases. The FGF axis has an important role in bone biology and mediates cell-to-cell communication. Therefore, we discuss here basic concepts of bone biology, FGF signaling axis, and FGF axis function in adult bone, to integrate these concepts in our current understanding of the role of FGF axis in bone metastases.

Purpose: Cabozantinib, an oral inhibitor of c-MET/VEGFR2 signaling, improved progression-free survival (mPFS) but not overall survival (OS) in metastatic castrate-resistant prostate cancer. We evaluated cabozantinib plus androgen deprivation therapy (ADT) in hormone-naïve metastatic prostate cancer (HNMPCa). Patients and Methods: Patients received ADT plus cabozantinib starting at 60 mg daily. The primary endpoint was castrate-resistant PFS by radiographic criteria, clinical progression, or receipt of additional therapy. Secondary endpoints included OS, safety, radiographic responses, and biomarker modulation. Results: Sixty-two patients received treatment. With a median follow-up of 31.2 months, the mPFS was 16.1 months (95% CI, 14.6–22.7 months), and mOS was not reached. Reductions in PSA ≥ 90%, bone-specific alkaline phosphatase ≥ 50%, and urine N-telopeptides ≥ 50% occurred in 83%, 87%, and 86% of evaluable patients, respectively. Responses in bone scan and measurable disease were observed in 81% of and 90% of evaluable patients, respectively. Most common grade 3 adverse events were hypertension (19%), diarrhea (6%), and thromboembolic events (6%), and dose reductions occurred in 85% of patients. Analysis of baseline cytokine and angiogenic factors (CAFs) revealed that higher plasma concentrations of Lumican, CXCL5, CD25, and CD30 were associated with shorter PFS as was high tumor expression of pFGFR1. Conclusions: Cabozantinib plus ADT has promising clinical activity in HNMPCa. CAF profiles and tissue markers suggest candidate prognostic and predictive markers of cabozantinib benefit and provide insights for rational therapy combinations.

Multi-tyrosine kinase inhibitors (MTKIs) have thus far had limited success in the treatment of castration-resistant prostate cancer (CRPC). Here, we report a phase I-cleared orally bioavailable MTKI, ESK981, with a novel autophagy inhibitory property that decreased tumor growth in diverse preclinical models of CRPC. The anti-tumor activity of ESK981 was maximized in immunocompetent tumor environments where it upregulated CXCL10 expression through the interferon gamma pathway and promoted functional T cell infiltration, which resulted in enhanced therapeutic response to immune checkpoint blockade. Mechanistically, we identify the lipid kinase PIKfyve as the direct target of ESK981. PIKfyve-knockdown recapitulated ESK981's anti-tumor activity and enhanced the therapeutic benefit of immune checkpoint blockade. Our study reveals that targeting PIKfyve via ESK981 turns tumors from cold into hot through inhibition of autophagy, which may prime the tumor immune microenvironment in advanced prostate cancer patients and be an effective treatment strategy alone or in combination with immunotherapies.

Background African American (AA) patients have higher cancer mortality rates and shorter survival times compared to European American (EA) patients. Despite a significant focus on socioeconomic factors, recent findings strongly argue the existence of biological factors driving this disparity. Most of these factors have been described in a cancer-type specific context rather than a pan-cancer setting. Methods A novel in silico approach based on Gene Set Enrichment Analysis (GSEA) coupled to Transcription Factor enrichment was carried out to identify common biological drivers of pan-cancer racial disparity using The Cancer Genome Atlas (TCGA) dataset. Mitochondrial content in patient tissues was examined using a multi-cancer tissue microarray approach (TMA). Results Mitochondrial oxidative phosphorylation was uniquely enriched in AA tumors compared to EA tumors across various cancer types. AA tumors also showed strong enrichment for the ERR1-PGC1α-mediated transcriptional program, which has been implicated in mitochondrial biogenesis. TMA analysis revealed that AA cancers harbor significantly more mitochondria compared to their EA counterparts. Conclusions These findings highlight changes in mitochondria as a common distinguishing feature between AA and EA tumors in a pan-cancer setting, and provide the rationale for the repurposing of mitochondrial inhibitors to treat AA cancers.

Epigenetic changes that cause dysregulated gene expression during progression of androgen-independent prostate cancer (PCa) and metastatic skeletal lesions remain elusive. Here, we explored the role of histone demethylase NO66 in the pathogenesis of PCa and bone metastasis-related skeletal lesions. Tissue and cDNA microarrays of PCa were analyzed for NO66 mRNA and protein levels. We examined the effects of gain and loss of NO66 function on cell viability, colony formation, migration, invasion, and tumor-induced skeletal lesions in femoral bone. RNAseq and ChIPseq were performed to elucidate NO66-target genes in PCa. We report that NO66 levels were upregulated in advanced primary prostate tumors compared to normal tissue or tumors with low Gleason scores. Forced expression of NO66 promoted cell survival and invasion of PCa cells; whereas, knockdown of NO66 resulted in decreased cell survival and increased sensitivity to docetaxel. NO66-overexpressing PC3 cells implanted into the femoral bone of male SCID mice caused massive bone loss and stimulation of mouse osteoclast-promoting genes, including Dickkopf1, Cathepsin K, Nf-kβ,; and Calcr, suggesting a role for NO66 in tumor growth in bone and osteoclast activity. Combined RNAseq and ChIP-seq revealed that NO66 activates the survival gene MCL1, the invasion-associated genes IGFBP5 and MMP3, the pro-oncogenic genes CTNNB1 and CCND1, and the epigenetic modifier gene KMT2A in androgen-independent PCa. Our findings uncover the role of NO66 as a key oncogenic driver in PCa, causing osteolytic lesions through upstream epigenetic regulation of key genes for survival, invasion and metastasis, and pro-osteoclastic factors.

Unsupervised clustering and deconvolution analysis identifies three intrinsic subtypes of Metastatic Castration-Resistant Prostate Cancer (M-CRPC): AR pathway-positive Prostate Cancer (ARPC), Neuro Endocrine Prostate Cancer (NEPC), and a novel subtype endowed with hybrid epithelial/mesenchymal (E/M) and luminal progenitor-like traits (Mesenchymal and Stem-like PC, MSPC). Analysis of large patient datasets and in vitro studies support the notion that MSPC originates from ARPC as a consequence of therapy-induced lineage plasticity. Intriguingly, AR blockade instigates two separate and complementary processes: 1) transcriptional silencing of TP53 and hence acquisition of hybrid E/M and stem-like traits; and 2) inhibition of the BMP-SMAD pathway, which promotes resistance to the pro-apoptotic and anti-proliferative effects of AR inhibition. MSPC cell lines and prostate adenocarcinoma cells reprogrammed in vitro to MSPC exhibit a marked dependency on HER2/3 signaling. Moreover, combinations of the panHER inhibitor neratinib with enzalutamide or the mTORC1 inhibitor MLN0128 exhibit efficacy in preclinical models of mixed ARPC/MSPC or MSPC, respectively. Collectively, these results identify a novel subtype of M-CRPC, trace its origin to therapy induced lineage plasticity, and reveal its dependency on HER2/3 signaling.