Integrative clinical genomics of advanced prostate cancer.

Toward development of a precision medicine framework for metastatic, castration-resistant prostate cancer (mCRPC), we established a multi-institutional clinical sequencing infrastructure to conduct prospective whole-exome and transcriptome sequencing of bone or soft tissue tumor biopsies from a cohort of 150 mCRPC affected individuals. Aberrations of AR, ETS genes, TP53, and PTEN were frequent (40%-60% of cases), with TP53 and AR alterations enriched in mCRPC compared to primary prostate cancer. We identified new genomic alterations in PIK3CA/B, R-spondin, BRAF/RAF1, APC, ß-catenin, and ZBTB16/PLZF. Moreover, aberrations of BRCA2, BRCA1, and ATM were observed at substantially higher frequencies (19.3% overall) compared to those in primary prostate cancers. 89% of affected individuals harbored a clinically actionable aberration, including 62.7% with aberrations in AR, 65% in other cancer-related genes, and 8% with actionable pathogenic germline alterations. This cohort study provides clinically actionable information that could impact treatment decisions for these affected individuals.

PKCλ/ι inhibition activates an ULK2-mediated interferon response to repress tumorigenesis.

The interferon (IFN) pathway is critical for cytotoxic T cell activation, which is central to tumor immunosurveillance and successful immunotherapy. We demonstrate here that PKCλ/ι inactivation results in the hyper-stimulation of the IFN cascade and the enhanced recruitment of CD8+ T cells that impaired the growth of intestinal tumors. PKCλ/ι directly phosphorylates and represses the activity of ULK2, promoting its degradation through an endosomal microautophagy-driven ubiquitin-dependent mechanism. Loss of PKCλ/ι results in increased levels of enzymatically active ULK2, which, by direct phosphorylation, activates TBK1 to foster the activation of the STING-mediated IFN response. PKCλ/ι inactivation also triggers autophagy, which prevents STING degradation by chaperone-mediated autophagy. Thus, PKCλ/ι is a hub regulating the IFN pathway and three autophagic mechanisms that serve to maintain its homeostatic control. Importantly, single-cell multiplex imaging and bioinformatics analysis demonstrated that low PKCλ/ι levels correlate with enhanced IFN signaling and good prognosis in colorectal cancer patients.

A MIR17HG-derived long noncoding RNA provides an essential chromatin scaffold for protein interaction and myeloma growth.

Long noncoding RNAs (lncRNAs) can drive tumorigenesis and are susceptible to therapeutic intervention. Here, we used a large-scale CRISPR interference viability screen to interrogate cell-growth dependency to lncRNA genes in multiple myeloma (MM) and identified a prominent role for the miR-17-92 cluster host gene (MIR17HG). We show that an MIR17HG-derived lncRNA, named lnc-17-92, is the main mediator of cell-growth dependency acting in a microRNA- and DROSHA-independent manner. Lnc-17-92 provides a chromatin scaffold for the functional interaction between c-MYC and WDR82, thus promoting the expression of ACACA, which encodes the rate-limiting enzyme of de novo lipogenesis acetyl-coA carboxylase 1. Targeting MIR17HG pre-RNA with clinically applicable antisense molecules disrupts the transcriptional and functional activities of lnc-17-92, causing potent antitumor effects both in vitro and in vivo in 3 preclinical animal models, including a clinically relevant patient-derived xenograft NSG mouse model. This study establishes a novel oncogenic function of MIR17HG and provides potent inhibitors for translation to clinical trials.

Intra-epithelial non-canonical Activin A signaling safeguards prostate progenitor quiescence.

The healthy prostate is a relatively quiescent tissue. Yet, prostate epithelium overgrowth is a common condition during aging, associated with urinary dysfunction and tumorigenesis. For over thirty years, TGF-ß ligands have been known to induce cytostasis in a variety of epithelia, but the intracellular pathway mediating this signal in the prostate, and its relevance for quiescence, have remained elusive. Here, using mouse prostate organoids to model epithelial progenitors, we find that intra-epithelial non-canonical Activin A signaling inhibits cell proliferation in a Smad-independent manner. Mechanistically, Activin A triggers Tak1 and p38 ΜAPK activity, leading to p16 and p21 nuclear import. Spontaneous evasion from this quiescent state occurs upon prolonged culture, due to reduced Activin A secretion, a condition associated with DNA replication stress and aneuploidy. Organoids capable to escape quiescence in vitro are also able to implant with increased frequency into immunocompetent mice. This study demonstrates that non-canonical Activin A signaling safeguards epithelial quiescence in the healthy prostate, with potential implications for the understanding of cancer initiation, and the development of therapies targeting quiescent tumor progenitors.

Androgen receptor regulates a distinct transcription program in androgen-independent prostate cancer.

The evolution of prostate cancer from an androgen-dependent state to one that is androgen-independent marks its lethal progression. The androgen receptor (AR) is essential in both, though its function in androgen-independent cancers is poorly understood. We have defined the direct AR-dependent target genes in both androgen-dependent and -independent cancer cells by generating AR-dependent gene expression profiles and AR cistromes. In contrast to what is found in androgen-dependent cells, AR selectively upregulates M-phase cell-cycle genes in androgen-independent cells, including UBE2C, a gene that inactivates the M-phase checkpoint. We find that epigenetic marks at the UBE2C enhancer, notably histone H3K4 methylation and FoxA1 transcription factor binding, are present in androgen-independent cells and direct AR-enhancer binding and UBE2C activation. Thus, the role of AR in androgen-independent cancer cells is not to direct the androgen-dependent gene expression program without androgen, but rather to execute a distinct program resulting in androgen-independent growth.

Spatial transcriptomic analysis of virtual prostate biopsy reveals confounding effect of tissue heterogeneity on genomic signatures.

Genetic signatures have added a molecular dimension to prognostics and therapeutic decision-making. However, tumour heterogeneity in prostate cancer and current sampling methods could confound accurate assessment. Based on previously published spatial transcriptomic data from multifocal prostate cancer, we created virtual biopsy models that mimic conventional biopsy placement and core size. We then analysed the gene expression of different prognostic signatures (OncotypeDx®, Decipher®, Prostadiag®) using a step-wise approach with increasing resolution from pseudo-bulk analysis of the whole biopsy, to differentiation by tissue subtype (benign, stroma, tumour), followed by distinct tumour grade and finally clonal resolution. The gene expression profile of virtual tumour biopsies revealed clear differences between grade groups and tumour clones, compared to a benign control, which were not reflected in bulk analyses. This suggests that bulk analyses of whole biopsies or tumour-only areas, as used in clinical practice, may provide an inaccurate assessment of gene profiles. The type of tissue, the grade of the tumour and the clonal composition all influence the gene expression in a biopsy. Clinical decision making based on biopsy genomics should be made with caution while we await more precise targeting and cost-effective spatial analyses.

"Stromal cells in prostate cancer pathobiology: friends or foes?"

The genomic, epigenetic and metabolic determinants of prostate cancer pathobiology have been extensively studied in epithelial cancer cells. However, malignant cells constantly interact with the surrounding environment-the so-called tumour microenvironment (TME)-which may influence tumour cells to proliferate and invade or to starve and die. In that regard, stromal cells-including fibroblasts, smooth muscle cells and vasculature-associated cells-constitute an essential fraction of the prostate cancer TME. However, they have been largely overlooked compared to other cell types (i.e. immune cells). Indeed, their importance in prostate physiology starts at organogenesis, as the soon-to-be prostate stroma determines embryonal epithelial cells to commit toward prostatic differentiation. Later in life, the appearance of a reactive stroma is linked to the malignant transformation of epithelial cells and cancer progression. In this Review, we discuss the main mesenchymal cell populations of the prostate stroma, highlighting their dynamic role in the transition of the healthy prostate epithelium to cancer. A thorough understanding of those populations, their phenotypes and their transcriptional programs may improve our understanding of prostate cancer pathobiology and may help to exploit prostate stroma as a biomarker of patient stratification and as a therapeutic target.

Implementation of a prostate cancer-specific targeted sequencing panel for credentialing of patient-derived cell lines and genomic characterization of patient samples.

BACKGROUND: Primary and metastatic prostate cancers have low mutation rates and recurrent alterations in a small set of genes, enabling targeted sequencing of prostate cancer-associated genes as an efficient approach to characterizing patient samples (compared to whole-exome and whole-genome sequencing). For example, targeted sequencing provides a flexible, rapid, and cost-effective method for genomic assessment of patient-derived cell lines to evaluate fidelity to initial patient tumor samples. METHODS: We developed a prostate cancer-specific targeted next-generation sequencing (NGS) panel to detect alterations in 62 prostate cancer-associated genes as well as recurring gene fusions with ETS family members, representing the majority of common alterations in prostate cancer. We tested this panel on primary prostate cancer tissues and blood biopsies from patients with metastatic prostate cancer. We generated patient-derived cell lines from primary prostate cancers using conditional reprogramming methods and applied targeted sequencing to evaluate the fidelity of these cell lines to the original patient tumors. RESULTS: The prostate cancer-specific panel identified biologically and clinically relevant alterations, including point mutations in driver oncogenes and ETS family fusion genes, in tumor tissues from 29 radical prostatectomy samples. The targeted panel also identified genomic alterations in cell-free DNA and circulating tumor cells (CTCs) from patients with metastatic prostate cancer, and in standard prostate cancer cell lines. We used the targeted panel to sequence our set of patient-derived cell lines; however, no prostate cancer-specific mutations were identified in the tumor-derived cell lines, suggesting preferential outgrowth of normal prostate epithelial cells. CONCLUSIONS: We evaluated a prostate cancer-specific targeted NGS panel to detect common and clinically relevant alterations (including ETS family gene fusions) in prostate cancer. The panel detected driver mutations in a diverse set of clinical samples of prostate cancer, including fresh-frozen tumors, cell-free DNA, CTCs, and cell lines. Targeted sequencing of patient-derived cell lines highlights the challenge of deriving cell lines from primary prostate cancers and the importance of genomic characterization to credential candidate cell lines. Our study supports that a prostate cancer-specific targeted sequencing panel provides an efficient, clinically feasible approach to identify genetic alterations across a spectrum of prostate cancer samples and cell lines.

Neutrophil extracellular traps contribute to immunothrombosis in COVID-19 acute respiratory distress syndrome.

COVID-19 affects millions of patients worldwide, with clinical presentation ranging from isolated thrombosis to acute respiratory distress syndrome (ARDS) requiring ventilator support. Neutrophil extracellular traps (NETs) originate from decondensed chromatin released to immobilize pathogens, and they can trigger immunothrombosis. We studied the connection between NETs and COVID-19 severity and progression. We conducted a prospective cohort study of COVID-19 patients (n = 33) and age- and sex-matched controls (n = 17). We measured plasma myeloperoxidase (MPO)-DNA complexes (NETs), platelet factor 4, RANTES, and selected cytokines. Three COVID-19 lung autopsies were examined for NETs and platelet involvement. We assessed NET formation ex vivo in COVID-19 neutrophils and in healthy neutrophils incubated with COVID-19 plasma. We also tested the ability of neonatal NET-inhibitory factor (nNIF) to block NET formation induced by COVID-19 plasma. Plasma MPO-DNA complexes increased in COVID-19, with intubation (P < .0001) and death (P < .0005) as outcome. Illness severity correlated directly with plasma MPO-DNA complexes (P = .0360), whereas Pao2/fraction of inspired oxygen correlated inversely (P = .0340). Soluble and cellular factors triggering NETs were significantly increased in COVID-19, and pulmonary autopsies confirmed NET-containing microthrombi with neutrophil-platelet infiltration. Finally, COVID-19 neutrophils ex vivo displayed excessive NETs at baseline, and COVID-19 plasma triggered NET formation, which was blocked by nNIF. Thus, NETs triggering immunothrombosis may, in part, explain the prothrombotic clinical presentations in COVID-19, and NETs may represent targets for therapeutic intervention.

O-GlcNAc transferase couples MRE11 to transcriptionally active chromatin to suppress DNA damage.

BACKGROUND: Transcription, metabolism and DNA damage response are tightly regulated to preserve the genomic integrity, and O-GlcNAc transferase (OGT) is positioned to connect the three. Prostate cancer is the most common cancer in men, and androgen-ablation therapy halts disease progression. However, a significant number of prostate cancer patients develop resistance against anti-androgens, and this incurable disease is termed castration-resistant prostate cancer (CRPC). We have shown that combined inhibition of OGT and the transcription elongation kinase CDK9 induce CRPC-selective anti-proliferative effects. Here, we explain the functional basis for these combinatorial effects. METHODS: We used comprehensive mass spectrometry profiling of short-term CDK9 inhibitor effects on O-GlcNAcylated proteins in an isogenic cell line system that models transition from PC to CRPC. In addition, we used both ChIP-seq and RNA-seq profiling, and pulldown experiments in multiple CRPC models. Finally, we validated our findings in prostate cancer patient samples. RESULTS: Inhibition of CDK9 results in an OGT-dependent remodeling of the proteome in prostate cancer cells. More specifically, the activity of the DNA damage repair protein MRE11 is regulated in response to CDK9 inhibition in an OGT-dependent manner. MRE11 is enriched at the O-GlcNAc-marked loci. CDK9 inhibition does not decrease the expression of mRNAs whose genes are bound by both O-GlcNAc and MRE11. Combined inhibition of CDK9 and OGT or MRE11 further decreases RNA polymerase II activity, induces DNA damage signaling, and blocks the survival of prostate cancer cells. These effects are seen in CRPC cells but not in normal prostate cells. Mechanistically, OGT activity is required for MRE11 chromatin-loading in cells treated with CDK9 inhibitor. Finally, we show that MRE11 and O-GlcNAc are enriched at the prostate cancer-specific small nucleotide polymorphic sites, and the loss of MRE11 activity results in a hyper-mutator phenotype in patient tumors. CONCLUSIONS: Both OGT and MRE11 are essential for the repair of CDK9 inhibitor-induced DNA damage. Our study raises the possibility of targeting CDK9 to elicit DNA damage in CRPC setting as an adjuvant to other treatments.

Genetic ablation of FASN attenuates the invasive potential of prostate cancer driven by Pten loss.

Loss of the tumor suppressor gene Pten in murine prostate recapitulates human carcinogenesis and causes stromal proliferation surrounding murine prostate intraepithelial neoplasia (mPIN), which is reactive to microinvasion. In turn, invasion has been shown to be regulated in part by de novo fatty acid synthesis in prostate cancer. We therefore investigated the effects of genetic ablation of Fasn on invasive potential in prostate-specific Pten knockout mice. Combined genetic ablation of Fasn and Pten reduced the weight and volume of all the prostate lobes when compared to single knockouts. The stromal reaction to microinvasion and the cell proliferation that typically occurs in Pten knockout were largely abolished by Fasn knockout. To verify that Fasn knockout indeed results in decreased invasive potential, we show that genetic ablation and pharmacologic inhibition of FASN in prostate cancer cells significantly inhibit cellular motility and invasion. Finally, combined loss of PTEN with FASN overexpression was associated with lethality as assessed in 660 prostate cancer patients with 14.2 years of median follow-up. Taken together, these findings show that de novo lipogenesis contributes to the aggressive phenotype induced by Pten loss in murine prostate and targeting Fasn may reduce the invasive potential of prostate cancer driven by Pten loss. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Aneuploidy drives lethal progression in prostate cancer.

Aneuploidy, defined as chromosome gains and losses, is a hallmark of cancer. However, compared with other tumor types, extensive aneuploidy is relatively rare in prostate cancer. Thus, whether numerical chromosome aberrations dictate disease progression in prostate cancer patients is not known. Here, we report the development of a method based on whole-transcriptome profiling that allowed us to identify chromosome-arm gains and losses in 333 primary prostate tumors. In two independent cohorts (n = 404) followed prospectively for metastases and prostate cancer-specific death for a median of 15 years, increasing extent of tumor aneuploidy as predicted from the tumor transcriptome was strongly associated with higher risk of lethal disease. The 23% of patients whose tumors had five or more predicted chromosome-arm alterations had 5.3 times higher odds of lethal cancer (95% confidence interval, 2.2 to 13.1) than those with the same Gleason score and no predicted aneuploidy. Aneuploidy was associated with lethality even among men with high-risk Gleason score 8-to-10 tumors. These results point to a key role of aneuploidy in driving aggressive disease in primary prostate cancer.

Inhibition of de novo lipogenesis targets androgen receptor signaling in castration-resistant prostate cancer.

A hallmark of prostate cancer progression is dysregulation of lipid metabolism via overexpression of fatty acid synthase (FASN), a key enzyme in de novo fatty acid synthesis. Metastatic castration-resistant prostate cancer (mCRPC) develops resistance to inhibitors of androgen receptor (AR) signaling through a variety of mechanisms, including the emergence of the constitutively active AR variant V7 (AR-V7). Here, we developed an FASN inhibitor (IPI-9119) and demonstrated that selective FASN inhibition antagonizes CRPC growth through metabolic reprogramming and results in reduced protein expression and transcriptional activity of both full-length AR (AR-FL) and AR-V7. Activation of the reticulum endoplasmic stress response resulting in reduced protein synthesis was involved in IPI-9119-mediated inhibition of the AR pathway. In vivo, IPI-9119 reduced growth of AR-V7-driven CRPC xenografts and human mCRPC-derived organoids and enhanced the efficacy of enzalutamide in CRPC cells. In human mCRPC, both FASN and AR-FL were detected in 87% of metastases. AR-V7 was found in 39% of bone metastases and consistently coexpressed with FASN. In patients treated with enzalutamide and/or abiraterone FASN/AR-V7 double-positive metastases were found in 77% of cases. These findings provide a compelling rationale for the use of FASN inhibitors in mCRPCs, including those overexpressing AR-V7.

Genomic correlates of clinical outcome in advanced prostate cancer.

Heterogeneity in the genomic landscape of metastatic prostate cancer has become apparent through several comprehensive profiling efforts, but little is known about the impact of this heterogeneity on clinical outcome. Here, we report comprehensive genomic and transcriptomic analysis of 429 patients with metastatic castration-resistant prostate cancer (mCRPC) linked with longitudinal clinical outcomes, integrating findings from whole-exome, transcriptome, and histologic analysis. For 128 patients treated with a first-line next-generation androgen receptor signaling inhibitor (ARSI; abiraterone or enzalutamide), we examined the association of 18 recurrent DNA- and RNA-based genomic alterations, including androgen receptor (AR) variant expression, AR transcriptional output, and neuroendocrine expression signatures, with clinical outcomes. Of these, only RB1 alteration was significantly associated with poor survival, whereas alterations in RB1, AR, and TP53 were associated with shorter time on treatment with an ARSI. This large analysis integrating mCRPC genomics with histology and clinical outcomes identifies RB1 genomic alteration as a potent predictor of poor outcome, and is a community resource for further interrogation of clinical and molecular associations.

Fatty acid synthase as a potential new therapeutic target for cervical cancer.

Fatty acid synthase (FASN) is the rate-limiting enzyme for the de novo synthesis of fatty acids in the cytoplasm of tumour cells. Many tumour cells express high levels of FASN, and its expression is associated with a poorer prognosis. Cervical cancer is a major public health problem, representing the fourth most common cancer affecting women worldwide. To date, only a few in silico studies have correlated FASN expression with cervical cancer. This study aimed to investigate in vitro FASN expression in premalignant lesions and cervical cancer samples and the effects of a FASN inhibitor on cervical cancer cells. FASN expression was observed in all cervical cancer samples with increased expression at more advanced cervical cancer stages. The FASN inhibitor (orlistat) reduced the in vitro cell viability of cervical cancer cells (C-33A, ME-180, HeLa and SiHa) in a time-dependent manner and triggered apoptosis. FASN inhibitor also led to cell cycle arrest and autophagy. FASN may be a potential therapeutic target for cervical cancer, and medicinal chemists, pharmaceutical researchers and formulators should consider this finding in the development of new treatment approaches for this cancer type.

Association between CD8 and PD-L1 expression and outcomes after radical prostatectomy for localized prostate cancer.

BACKGROUND: Characterization of markers of both immune suppression and activation may provide more prognostic information than assessment of single markers in localized prostate cancer. We therefore sought to determine the association between CD8 and PD-L1 expression in localized prostate tumors and biochemical recurrence (BCR) and metastasis-free survival (MFS). METHODS: Tissue microarrays were constructed on 109 men undergoing radical prostatectomy (RP) for localized prostate cancer at Dana-Farber Cancer Institute between 1991 and 2008. Fluorescence immunohistochemistry was used to evaluate the expression of six immune markers (CD3, CD4, CD8, PD-1, PD-L1, FOXP3). Quantitative multispectral imaging analysis was used to calculate the density of each marker, which was dichotomized by the median as "high" or "low." Cox proportional hazards regression models and Kaplan-Meier analyses were used to analyze associations between immune marker densities and time to BCR and MFS. RESULTS: Over a median follow-up of 8.1 years, 55 (51%) and 39 (36%) men developed BCR and metastases, respectively. Median time to BCR was shorter in men with low CD8 (hazard ratio [HR] = 2.27 [1.27-4.08]) and high PD-L1 expression (HR = 2.03 [1.17-3.53]). While neither low CD8 or high PD-L1 alone were independent predictors of BCR or MFS on multivariable analysis, men with low CD8 and/or high PD-L1 had a significantly shorter time to BCR (median 3.5 years vs. NR) and MFS (median 10.8 vs. 18.4 years) compared to those with high CD8 and low PD-L1 expression. The main limitation is the retrospective and singe-center nature of the study. CONCLUSION: The presence of higher CD8 and lower PD-L1 expression in prostatectomy specimens was associated a low risk of biochemical relapse and metastatic disease. These findings are hypothesis-generating and further study is needed.

Transcriptional landscape of PTEN loss in primary prostate cancer.

BACKGROUND: PTEN is the most frequently lost tumor suppressor in primary prostate cancer (PCa) and its loss is associated with aggressive disease. However, the transcriptional changes associated with PTEN loss in PCa have not been described in detail. In this study, we highlight the transcriptional changes associated with PTEN loss in PCa. METHODS: Using a meta-analysis approach, we leveraged two large PCa cohorts with experimentally validated PTEN and ERG status by Immunohistochemistry (IHC), to derive a transcriptomic signature of PTEN loss, while also accounting for potential confounders due to ERG rearrangements. This signature was expanded to lncRNAs using the TCGA quantifications from the FC-R2 expression atlas. RESULTS: The signatures indicate a strong activation of both innate and adaptive immune systems upon PTEN loss, as well as an expected activation of cell-cycle genes. Moreover, we made use of our recently developed FC-R2 expression atlas to expand this signature to include many non-coding RNAs recently annotated by the FANTOM consortium. Highlighting potential novel lncRNAs associated with PTEN loss and PCa progression. CONCLUSION: We created a PCa specific signature of the transcriptional landscape of PTEN loss that comprises both the coding and an extensive non-coding counterpart, highlighting potential new players in PCa progression. We also show that contrary to what is observed in other cancers, PTEN loss in PCa leads to increased activation of the immune system. These findings can help the development of new biomarkers and help guide therapy choices.

Inhibition of CDK9 activity compromises global splicing in prostate cancer cells.

Cyclin-dependent kinase 9 (CDK9) phosphorylates RNA polymerase II to promote productive transcription elongation. Here we show that short-term CDK9 inhibition affects the splicing of thousands of mRNAs. CDK9 inhibition impairs global splicing and there is no evidence for a coordinated response between the alternative splicing and the overall transcriptome. Alternative splicing is a feature of aggressive prostate cancer (CRPC) and enables the generation of the anti-androgen resistant version of the ligand-independent androgen receptor, AR-v7. We show that CDK9 inhibition results in the loss of AR and AR-v7 expression due to the defects in splicing, which sensitizes CRPC cells to androgen deprivation. Finally, we demonstrate that CDK9 expression increases as PC cells develop CRPC-phenotype both in vitro and also in patient samples. To conclude, here we show that CDK9 inhibition compromises splicing in PC cells, which can be capitalized on by targeting the PC-specific addiction androgen receptor.

ETV1 directs androgen metabolism and confers aggressive prostate cancer in targeted mice and patients.

Distinguishing aggressive from indolent disease and developing effective therapy for advanced disease are the major challenges in prostate cancer research. Chromosomal rearrangements involving ETS transcription factors, such as ERG and ETV1, occur frequently in prostate cancer. How they contribute to tumorigenesis and whether they play similar or distinct in vivo roles remain elusive. Here we show that in mice with ERG or ETV1 targeted to the endogenous Tmprss2 locus, either factor cooperated with loss of a single copy of Pten, leading to localized cancer, but only ETV1 appeared to support development of invasive adenocarcinoma under the background of full Pten loss. Mechanistic studies demonstrated that ERG and ETV1 control a common transcriptional network but largely in an opposing fashion. In particular, while ERG negatively regulates the androgen receptor (AR) transcriptional program, ETV1 cooperates with AR signaling by favoring activation of the AR transcriptional program. Furthermore, we found that ETV1 expression, but not that of ERG, promotes autonomous testosterone production. Last, we confirmed the association of an ETV1 expression signature with aggressive disease and poorer outcome in patient data. The distinct biology of ETV1-associated prostate cancer suggests that this disease class may require new therapies directed to underlying programs controlled by ETV1.