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Numerous cancers, including prostate cancer (PCa), are addicted to transcription programs driven by specific genomic regions known as super-enhancers (SEs). The robust transcription of genes at such SEs is enabled by the formation of phase-separated condensates by transcription factors and coactivators with intrinsically disordered regions. The androgen receptor (AR), the main oncogenic driver in PCa, contains large disordered regions and is co-recruited with the transcriptional coactivator mediator complex subunit 1 (MED1) to SEs in androgen-dependent PCa cells, thereby promoting oncogenic transcriptional programs. In this work, we reveal that full-length AR forms foci with liquid-like properties in different PCa models. We demonstrate that foci formation correlates with AR transcriptional activity, as this activity can be modulated by changing cellular foci content chemically or by silencing MED1. AR ability to phase separate was also validated in vitro by using recombinant full-length AR protein. We also demonstrate that AR antagonists, which suppress transcriptional activity by targeting key regions for homotypic or heterotypic interactions of this receptor, hinder foci formation in PCa cells and phase separation in vitro. Our results suggest that enhanced compartmentalization of AR and coactivators may play an important role in the activation of oncogenic transcription programs in androgen-dependent PCa.

S1. The relative expression of KLK3/PSA. S2. Kaplan-Meier analysis of prostate cancer outcome was obtained from GEPIA tool. S3. LNCaP cells with the indicated treatments were seeded in the upper chamber of the Boyden's transwell chamber. S4. LNCaP cells with the indicated treatments were seeded in the upper chamber of the Boyden's transwell chamber which were coated with 1:20 diluted Matrigel. S5. LNCaP cells with the indicated treatments were seeded in the upper chamber of the Boyden's transwell chamber. S6. Snapshots form the AR ChIP-seq showing AR binding to the ARBS. S7. Screenshot from the AR ChIP-seq shows marked reduction in AR binding to the ARBS located at ~ 30kb from the NDRG1 after LINC00844 knock-down in LNCaP cells. S8. LNCaP cells with the indicated treatments were seeded in the upper chamber of the Boyden's transwell chamber. S9. LNCaP cells we co-transfected with the with the indicated siRNA and plasmids and seeded in the upper chamber of the Boyden's transwell chamber. S10. LNCaP cells we co-transfected with the with the indicated siRNA and plasmids cells were harvested and the required amount of cells were used for the migration and invasion assay and rest were lysed for western blot analysis.

The human genome is mostly transcribed, yielding a rich repository of noncoding transcripts that are involved in a myriad of biological processes including cancer. However, how many noncoding transcripts such as long noncoding RNAs (lncRNA) function in cancer is still unclear. This study identified a novel set of clinically relevant androgen-regulated lncRNAs in prostate cancer. Among this group, LINC00844 was demonstrated to be a direct androgen-regulated target that is actively transcribed in androgen receptor (AR)–dependent prostate cancer cells. The expression of LINC00844 is higher in normal prostate compared with malignant and metastatic prostate cancer clinical specimens, and patients with low expression had a poor prognosis and significantly increased biochemical recurrence, suggesting LINC00844 functions in suppressing tumor progression and metastasis. Indeed, in vitro loss-of-function studies revealed that LINC00844 prevents prostate cancer cell migration and invasion. Moreover, findings from gene expression profiling analysis indicated that LINC00844 functions in trans, affecting global androgen-regulated gene transcription. Mechanistic evidence reveals that LINC00844 is important in facilitating AR binding to the chromatin. Finally, LINC00844 mediates its phenotypic effects in part by activating the expression of NDRG1, a crucial cancer metastasis suppressor. Collectively, LINC00844 is a novel coregulator of AR that plays a central role in the androgen transcriptional network and the development and progression of prostate cancer.Implications:This study highlights the function of the lncRNA, LINC00844, in regulating global AR-regulated genes in prostate cancer by modulating AR binding to chromatin.

S1. Differentially regulated lncRNAs FDR

Prostate cancer (PCa) patients undergoing androgen deprivation therapy almost invariably develop castration-resistant prostate cancer (CRPC). Targeting the androgen receptor (AR) Binding Function-3 (BF3) site offers a promising option to treat CRPC. However, BF3 inhibitors have been limited by poor potency or inadequate metabolic stability. Through extensive medicinal chemistry, molecular modeling, and biochemistry, we identified 2-(5,6,7-trifluoro-1H-Indol-3-yl)-quinoline-5-carboxamide (VPC-13789), a potent AR BF3 antagonist with markedly improved pharmacokinetic properties. We demonstrate that VPC-13789 suppresses AR-mediated transcription, chromatin binding, and recruitment of coregulatory proteins. This novel AR antagonist selectively reduces the growth of both androgen-dependent and enzalutamide-resistant PCa cell lines. Having demonstrated in vitro efficacy, we developed an orally bioavailable prodrug that reduced PSA production and tumor volume in animal models of CRPC with no observed toxicity. VPC-13789 is a potent, selective, and orally bioavailable antiandrogen with a distinct mode of action that has a potential as novel CRPC therapeutics.

Androgen receptor (AR) is a master transcription factor that drives prostate cancer (PCa) development and progression. Alterations in the expression or activity of AR coregulators significantly impact the outcome of the disease. Using a proteomics approach, we identified the tripartite motif‐containing 33 (TRIM33) as a novel transcriptional coactivator of AR. We demonstrate that TRIM33 facilitates AR chromatin binding to directly regulate a transcription program that promotes PCa progression. TRIM33 further stabilizes AR by protecting it from Skp2‐mediated ubiquitination and proteasomal degradation. We also show that TRIM33 is essential for PCa tumor growth by avoiding cell‐cycle arrest and apoptosis, and TRIM33 knockdown sensitizes PCa cells to AR antagonists. In clinical analyses, we find TRIM33 upregulated in multiple PCa patient cohorts. Finally, we uncover an AR‐TRIM33‐coactivated gene signature highly expressed in PCa tumors and predict disease recurrence. Overall, our results reveal that TRIM33 is an oncogenic AR coactivator in PCa and a potential therapeutic target for PCa treatment.

Prostate cancer (PCa) patients undergoing androgen deprivation therapy almost invariably develop castration-resistant prostate cancer (CRPC). Targeting the androgen receptor (AR) Binding Function-3 (BF3) site offers a promising option to treat CRPC. However, BF3 inhibitors have been limited by poor potency or inadequate metabolic stability. Through extensive medicinal chemistry, molecular modeling, and biochemistry, we identified 2-(5,6,7-trifluoro-1

Summary Pyruvate is a key metabolite in glycolysis and the tricarboxylic acid (TCA) cycle. Exogenous pyruvate modulates metabolism, provides cellular protection, and is essential for the maintenance of human preimplantation embryos and human embryonic stem cells (hESCs). However, little is known about how pyruvate contributes to cell-fate determination during epiblast stage. In this study, we used hESCs as a model to demonstrate that elevated exogenous pyruvate shifts metabolic balance toward oxidative phosphorylation in both maintenance and differentiation conditions. During differentiation, pyruvate potentiates mesoderm and endoderm lineage specification. Pyruvate production and its mitochondrial metabolism are required in BMP4-induced mesoderm differentiation. However, the TCA-cycle metabolites do not have the same effect as pyruvate on differentiation. Further study shows that pyruvate increases AMP/ATP ratio, activates AMPK, and modulates the mTOR pathway to enhance mesoderm differentiation. This study reveals that exogenous pyruvate not only controls metabolism but also modulates signaling pathways in hESC differentiation., Graphical Abstract, Highlights • Exogenous pyruvate enhances TCA-cycle metabolism in hESCs • Exogenous pyruvate promotes BMP4-induced mesoderm differentiation • Exogenous pyruvate influences differentiation through AMPK/mTOR pathways, In this report, Chen and colleagues demonstrate that pyruvate promotes mesoderm differentiation in human embryonic stem cells. Pyruvate elevates TCA-cycle metabolism and modulates AMPK and mTOR pathways to promote BMP4-induced mesoderm differentiation. This discovery highlights that pyruvate as a common metabolite can regulate signaling pathways in cell-fate determination.

Numerous cancers, including prostate cancer (PCa), are addicted to transcription programs driven by superenhancers (SEs). The transcription of genes at SEs is enabled by the formation of phase-separated condensates by transcription factors and co-activators with intrinsically disordered regions. The androgen receptor (AR), main oncogenic driver in PCa, contains large disordered regions and is co-recruited with the co-activator MED1 to SEs to promote oncogenic programs. In this work, we show that dynamic AR-rich, liquid-like foci form in PCa models upon androgen stimulation and correlate with AR transcriptional activity. The co-activator MED1 plays an essential role in the formation of AR foci while AR antagonists hinder their formation. These results suggest that enhanced compartmentalization of AR and co-activators at SEs may play an important role in the activation of oncogenic transcription programs in PCa. A better understanding of the assembly and the regulation of these AR-rich compartments may provide novel therapeutic options.

Numerous cancers, including prostate cancer (PCa), have been shown to be addicted to transcription programs driven by specific genomic sites known as superenhancers (SEs). Recently, it has been proposed that the robust transcription of genes at such SEs is enabled by the formation of phase-separated condensates by transcription factors and coactivators with intrinsically disordered regions. The androgen receptor (AR), the main oncogenic driver in PCa, contains large disordered regions and is co-recruited with the transcriptional coactivator MED1 to SEs in androgen-dependent prostate cancer cells, thereby promoting oncogenic transcriptional programs. In this work, we show that AR-rich, liquid-like foci form in prostate cancer models upon androgen stimulation. We reveal that foci formation correlates with AR transcriptional activity, which can be modulated by changing cellular foci content genetically or chemically. We also demonstrate that the transcriptional coactivator MED1 plays an essential role in the formation of transcriptionally active AR-rich foci and that AR antagonists that block cofactor recruitment or DNA binding hinder foci formation and thus AR transcriptional activity. The liquid like properties of the condensates were also validated in-vitro by using recombinant AR protein. Using clinical specimens, we detected the interaction between AR and MED1 in advanced forms of prostate cancer and not in benign tissues. These results suggest that enhanced compartmentalization of AR and coactivators at SEs may play an important role in the activation of oncogenic transcription programs in androgen-dependent PCa. A better understanding of the assembly and the regulation of these AR-rich compartments may provide novel therapeutic options for PCa by targeting downstream events of androgen activation and DNA binding of AR. Citation Format: Fan Zhang, Maitree Biswas, Joseph Lee, Shreyas Lingadahalli, Samantha Wong, Christopher Wells, Neetu Saxena, Bei Sun, Ana K. Parra-Nuñez, Christophe Sanchez, Jane Foo, Novia Chan, Lauren Ung, Nabeel Khan, Umut Berkay Altıntaş, Jennifer M. Bui, Yuzhuo Wang, Ladan Fazli, Paul S. Rennie, Nathan Lack, Artem Cherkasov, Martin E. Gleave, Joerg Gsponer, Nada Lallous. Dynamic phase separation of the androgen receptor and its coactivators to regulate gene expression [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 5729.

Additional file 4. Review history.

Additional file 1: Fig.S1- S14. Supplementary figures.

Additional file 2. All the publicly available data used.

Androgen receptor (AR) is critical to the initiation, growth and progression of almost all prostate cancers. Once activated, the AR binds to cis-regulatory enhancer elements on DNA that drive gene expression. Yet, there are 10-100x more binding sites than differentially expressed genes. It still remains unclear how individual sites contribute to AR-mediated transcription. While descriptive functional genomic approaches broadly correlate with enhancer activity, they do not provide the locus-specific resolution needed to delineate the underlying regulatory logic of AR-mediated transcription. Therefore, we functionally tested all commonly occuring clinical AR binding sites with Self-Transcribing Active Regulatory Regions sequencing (STARRseq) to generate the first map of intrinsic AR enhancer activity. This approach is not significantly affected by endogenous chromatin modifications and measures the potential enhancer activity at each cis-regulatory element. Interestingly we found that only 7% of AR binding sites displayed increased enhancer activity upon hormonal stimulation. Instead, the vast majority of AR binding sites were either inactive (81%) or constitutively active enhancers (11%). These annotations strongly correlated with enhancer-associated features in both cell line and clinical prostate cancer. With these validated annotations we next investigated the effect of each enhancer class on transcription and found that AR-driven inducible enhancers frequently interacted with promoters, forming central chromosomal loops critical for gene transcription. We demonstrated that these inducible enhancers act as regulatory hubs that increase contacts with both other AR binding sites and gene promoters. This functional map was used to identify a somatic mutation that significantly reduces the expression of a commonly mutated AR-regulated tumour suppressor. Together, our data reveal a complex interplay between different AR binding sites that work in a highly coordinated manner to drive gene transcription.

The human genome is mostly transcribed, yielding a rich repository of noncoding transcripts that are involved in a myriad of biological processes including cancer. However, how many noncoding transcripts such as long noncoding RNAs (lncRNA) function in cancer is still unclear. This study identified a novel set of clinically relevant androgen-regulated lncRNAs in prostate cancer. Among this group, LINC00844 was demonstrated to be a direct androgen-regulated target that is actively transcribed in androgen receptor (AR)–dependent prostate cancer cells. The expression of LINC00844 is higher in normal prostate compared with malignant and metastatic prostate cancer clinical specimens, and patients with low expression had a poor prognosis and significantly increased biochemical recurrence, suggesting LINC00844 functions in suppressing tumor progression and metastasis. Indeed, in vitro loss-of-function studies revealed that LINC00844 prevents prostate cancer cell migration and invasion. Moreover, findings from gene expression profiling analysis indicated that LINC00844 functions in trans, affecting global androgen-regulated gene transcription. Mechanistic evidence reveals that LINC00844 is important in facilitating AR binding to the chromatin. Finally, LINC00844 mediates its phenotypic effects in part by activating the expression of NDRG1, a crucial cancer metastasis suppressor. Collectively, LINC00844 is a novel coregulator of AR that plays a central role in the androgen transcriptional network and the development and progression of prostate cancer. Implications: This study highlights the function of the lncRNA, LINC00844, in regulating global AR-regulated genes in prostate cancer by modulating AR binding to chromatin.

The aberrant activities of transcription factors such as the androgen receptor (AR) underpin prostate cancer development. While the AR cis-regulation has been extensively studied in prostate cancer, information pertaining to the spatial architecture of the AR transcriptional circuitry remains limited. In this paper, we propose a novel framework to profile long-range chromatin interactions associated with AR and its collaborative transcription factor, erythroblast transformation-specific related gene (ERG), using chromatin interaction analysis by paired-end tag (ChIA-PET). We identified ERG-associated long-range chromatin interactions as a cooperative component in the AR-associated chromatin interactome, acting in concert to achieve coordinated regulation of a subset of AR target genes. Through multifaceted functional data analysis, we found that AR-ERG interaction hub regions are characterized by distinct functional signatures, including bidirectional transcription and cotranscription factor binding. In addition, cancer-associated long noncoding RNAs were found to be connected near protein-coding genes through AR-ERG looping. Finally, we found strong enrichment of prostate cancer genome-wide association study (GWAS) single nucleotide polymorphisms (SNPs) at AR-ERG co-binding sites participating in chromatin interactions and gene regulation, suggesting GWAS target genes identified from chromatin looping data provide more biologically relevant findings than using the nearest gene approach. Taken together, our results revealed an AR-ERG-centric higher-order chromatin structure that drives coordinated gene expression in prostate cancer progression and the identification of potential target genes for therapeutic intervention.

The human genome is mostly transcribed, yielding a rich repository of noncoding transcripts that are involved in a myriad of biological processes including cancer. However, how many noncoding transcripts such as long noncoding RNAs (lncRNA) function in cancer is still unclear. This study identified a novel set of clinically relevant androgen-regulated lncRNAs in prostate cancer. Among this group

The majority of the human genome is transcribed, yielding a rich repository of non-coding transcripts that are involved in a myriad of biological processes including cancer. However, how non-coding transcripts such as long non-coding RNAs (lncRNAs) function in prostate cancer is still unclear. In this study, we have identified a novel set of clinically relevant androgen-regulated lncRNAs in prostate cancer. Among this group, we showed LINC00844 is a direct androgen-regulated target that is actively transcribed in androgen receptor (AR)-dependent prostate cancer cells. The expression of LINC00844 is higher in normal prostate compared to malignant and metastatic prostate cancer samples and patients with low expression demonstrate poor prognosis and significantly increased biochemical recurrence, suggesting LINC00844 may function in suppressing tumor progression and metastasis. Indeed,in-vitroloss-of-function studies revealed that LINC00844 prevents prostate cancer cell migration and invasion. Moreover, findings from gene expression analysis indicated that LINC00844 functions intrans, affecting global androgen-regulated gene transcription. Mechanistically, we provide evidence to show LINC00844 is important in facilitating AR binding to the chromatin. Finally, we demonstrated LINC00844 mediates its phenotypic effects in part by activating the expression of NDRG1, a crucial cancer metastasis suppressor. Collectively, our findings suggest LINC00844 is a novel coregulator of AR that plays a central role in the androgen transcriptional network and the development and progression of prostate cancer.