Substrate selectivity and inhibition of the human lysyl hydroxylase JMJD7.

Jumonji-C (JmjC) domain-containing protein 7 (JMJD7) is a human Fe(II) and 2-oxoglutarate dependent oxygenase that catalyzes stereospecific C3-hydroxylation of lysyl-residues in developmentally regulated GTP binding proteins 1 and 2 (DRG1/2). We report studies exploring a diverse set of lysine derivatives incorporated into the DRG1 peptides as potential human JMJD7 substrates and inhibitors. The results indicate that human JMJD7 has a relatively narrow substrate scope beyond lysine compared to some other JmjC hydroxylases and lysine-modifying enzymes. The geometrically constrained (E)-dehydrolysine is an efficient alternative to lysine for JMJD7-catalyzed C3-hydroxylation. γ-Thialysine and γ-azalysine undergo C3-hydroxylation, followed by degradation to formylglycine. JMJD7 also catalyzes the S-oxidation of DRG1-derived peptides possessing methionine and homomethionine residues in place of lysine. Inhibition assays show that DRG1 variants possessing cysteine/selenocysteine instead of the lysine residue efficiently inhibit JMJD7 via cross-linking. The overall results inform on the substrate selectivity and inhibition of human JMJD7, which will help enable the rational design of selective small-molecule and peptidomimetic inhibitors of JMJD7.

Jumonji histone demethylases are therapeutic targets in small cell lung cancer.

Small cell lung cancer (SCLC) is a recalcitrant cancer of neuroendocrine (NE) origin. Changes in therapeutic approaches against SCLC have been lacking over the decades. Here, we use preclinical models to identify a new therapeutic vulnerability in SCLC consisting of the targetable Jumonji lysine demethylase (KDM) family. We show that Jumonji demethylase inhibitors block malignant growth and that etoposide-resistant SCLC cell lines are particularly sensitive to Jumonji inhibition. Mechanistically, small molecule-mediated inhibition of Jumonji KDMs activates endoplasmic reticulum (ER) stress genes, upregulates ER stress signaling, and triggers apoptotic cell death. Furthermore, Jumonji inhibitors decrease protein levels of SCLC NE markers INSM1 and Secretogranin-3 and of driver transcription factors ASCL1 and NEUROD1. Genetic knockdown of KDM4A, a Jumonji demethylase highly expressed in SCLC and a known regulator of ER stress genes, induces ER stress response genes, decreases INSM1, Secretogranin-3, and NEUROD1 and inhibits proliferation of SCLC in vitro and in vivo. Lastly, we demonstrate that two different small molecule Jumonji KDM inhibitors (pan-inhibitor JIB-04 and KDM4 inhibitor SD70) block the growth of SCLC tumor xenografts in vivo. Our study highlights the translational potential of Jumonji KDM inhibitors against SCLC, a clinically feasible approach in light of recently opened clinical trials evaluating this drug class, and establishes KDM4A as a relevant target across SCLC subtypes.

Structure-based mapping of the histone-binding pocket of KDM4D using functionalized tetrazole and pyridine core compounds.

KDM4 histone demethylases became an exciting target for inhibitor development as the evidence linking them directly to tumorigenesis mounts. In this study, we set out to better understand the binding cavity using an X-ray crystallographic approach to provide a detailed landscape of possible interactions within the under-investigated region of KDM4. Our design strategy was based on utilizing known KDM binding motifs, such as nicotinic acid and tetrazolylhydrazides, as core motifs that we decided to enrich with flexible tails to map the distal histone binding site. The resulting X-ray structures of the novel compounds bound to KDM4D, a representative of the KDM4 family, revealed the interaction pattern with distal residues in the histone-binding site. The most prominent protein rearrangement detected upon ligand binding is the loop movement that blocks the accessibility to the histone binding site. Apart from providing new sites that potential inhibitors can target, the novel compounds may prove helpful in exploring the capacity of ligands to bind in sites distal to the cofactor-binding site of other KDMs or 2-oxoglutarate (2OG)-dependent oxygenases. The case study proves that combining a strong small binding motif with flexible tails to probe the binding pocket will facilitate lead discovery in classical drug-discovery campaigns, given the ease of accessing X-ray quality crystals.

Discovery of an efficacious KDM5B PROTAC degrader GT-653 up-regulating IFN response genes in prostate cancer.

Epigenetic alterations promote cancer development by regulating the expression of various oncogenes and anti-oncogenes. Histone methylation modification represents a pivotal area in epigenetic research and numerous publications have demonstrated that aberrant histone methylation is highly correlated with tumorigenesis and development. As a key histone demethylase, lysine-specific demethylase 5B (KDM5B) demethylates lysine 4 of histone 3 (H3K4) and serves as a transcriptional repressor of certain tumor suppressor genes. Meanwhile, KDM5B inhibits STING-induced intrinsic immune response of tumor cells or recruits SETDB1 through non-enzymatic function to silence reverse transcription elements to promote immune escape. The conventional small molecule inhibitors can only inhibit the enzymatic function of KDM5B with no effect on the non-enzymatic function. In the article, we present the development of the first series of KDM5B degraders based on CPI-455 to inhibit the non-enzymatic function. Among them, GT-653 showed optimal KDM5B degradation efficiency in a ubiquitin proteasome-dependent manner. GT-653 efficiently reduced KDM5B protein levels without affecting KDM5B transcription. Interestingly, GT-653 increased H3K4me3 levels and activated the type-I interferon signaling pathway in 22RV1 cells without significant phenotypic response on cell proliferation.

KDM5 family as therapeutic targets in breast cancer: Pathogenesis and therapeutic opportunities and challenges.

Breast cancer (BC) is the most frequent malignant cancer diagnosis and is a primary factor for cancer deaths in women. The clinical subtypes of BC include estrogen receptor (ER) positive, progesterone receptor (PR) positive, human epidermal growth factor receptor 2 (HER2) positive, and triple-negative BC (TNBC). Based on the stages and subtypes of BC, various treatment methods are available with variations in the rates of progression-free disease and overall survival of patients. However, the treatment of BC still faces challenges, particularly in terms of drug resistance and recurrence. The study of epigenetics has provided new ideas for treating BC. Targeting aberrant epigenetic factors with inhibitors represents a promising anticancer strategy. The KDM5 family includes four members, KDM5A, KDM5B, KDM5C, and KDMD, all of which are Jumonji C domain-containing histone H3K4me2/3 demethylases. KDM5 proteins have been extensively studied in BC, where they are involved in suppressing or promoting BC depending on their specific upstream and downstream pathways. Several KDM5 inhibitors have shown potent BC inhibitory activity in vitro and in vivo, but challenges still exist in developing KDM5 inhibitors. In this review, we introduce the subtypes of BC and their current therapeutic options, summarize KDM5 family context-specific functions in the pathobiology of BC, and discuss the outlook and pitfalls of KDM5 inhibitors in this disease.

Co-targeting SKP2 and KDM5B inhibits prostate cancer progression by abrogating AKT signaling with induction of senescence and apoptosis.

BACKGROUND: Prostate cancer (PCa) is the second-leading cause of cancer mortalities in the United States and is the most commonly diagnosed malignancy in men. While androgen deprivation therapy (ADT) is the first-line treatment option to initial responses, most PCa patients invariably develop castration-resistant PCa (CRPC). Therefore, novel and effective treatment strategies are needed. The goal of this study was to evaluate the anticancer effects of the combination of two small molecule inhibitors, SZL-P1-41 (SKP2 inhibitor) and PBIT (KDM5B inhibitor), on PCa suppression and to delineate the underlying molecular mechanisms. METHODS: Human CRPC cell lines, C4-2B and PC3 cells, were treated with small molecular inhibitors alone or in combination, to assess effects on cell proliferation, migration, senescence, and apoptosis. RESULTS: SKP2 and KDM5B showed an inverse regulation at the translational level in PCa cells. Cells deficient in SKP2 showed an increase in KDM5B protein level, compared to that in cells expressing SKP2. By contrast, cells deficient in KDM5B showed an increase in SKP2 protein level, compared to that in cells with KDM5B intact. The stability of SKP2 protein was prolonged in KDM5B depleted cells as measured by cycloheximide chase assay. Cells deficient in KDM5B were more vulnerable to SKP2 inhibition, showing a twofold greater reduction in proliferation compared to cells with KDM5B intact (p < 0.05). More importantly, combined inhibition of KDM5B and SKP2 significantly decreased proliferation and migration of PCa cells as compared to untreated controls (p < 0.005). Mechanistically, combined inhibition of KDM5B and SKP2 in PCa cells abrogated AKT activation, resulting in an induction of both cellular senescence and apoptosis, which was measured via Western blot analysis and senescence-associated ß-galactosidase (SA-ß-Gal) staining. CONCLUSIONS: Combined inhibition of KDM5B and SKP2 was more effective at inhibiting proliferation and migration of CRPC cells, and this regimen would be an ideal therapeutic approach of controlling CRPC malignancy.

Structural simulation and selective inhibitor discovery study for histone demethylases KDM4E/6B from a computational perspective.

The methylation and demethylation of lysine and arginine side chains are fundamental processes in gene regulation and disease development. Histone lysine methylation, controlled by histone lysine methyltransferases (KMTs) and histone lysine demethylases (KDMs), plays a vital role in maintaining cellular homeostasis and has been implicated in diseases such as cancer and aging. This study focuses on two members of the lysine demethylase (KDM) family, KDM4E and KDM6B, which are significant in gene regulation and disease pathogenesis. KDM4E demonstrates selectivity for gene regulation, particularly concerning cancer, while KDM6B is implicated in inflammation and cancer. The study utilizes specific inhibitors, DA-24905 and GSK-J1, showcasing their exceptional selectivity for KDM4E and KDM6B, respectively. Employing an array of computational simulations, including sequence alignment, molecular docking, dynamics simulations, and free energy calculations, we conclude that although the binding cavities of KDM4E and KDM6B has high similarity, there are still some different crucial amino acid residues, indicating diverse binding forms between protein and ligands. Various interaction predominates when proteins are bound to different ligands, which also has significant effect on selective inhibition. These findings provide insights into potential therapeutic strategies for diseases by selectively targeting these KDM members.

Design, synthesis and biological evaluation of pyrimidine base hydroxamic acid derivatives as dual JMJD3 and HDAC inhibitors.

The Jumonji domain-containing protein demethylase 3 (JMJD3) and histone deacetylase (HADC) are related to various cancers and regard as antitumor targets for drug discovery. In this study, based on rational drug design strategy, we designed and synthesized a series of pyrimidine derivatives with hydroxamic acid as novel dual JMJD3 and HDAC inhibitors for synergistic cancer treatment. Compound A5b exhibited inhibitory potency against JMJD3 and HDAC1/6 simultaneously and favorable cytotoxicity against human cancer cells such as A549 and U937. Furthermore, mechanistic studies showed that A5b treatment in A549 cells increased the hypermethylation of histone H3K27 and hyperacetylation of H3K9, suppressed clonogenicity, migration and invasion of cancer cells. Besides, A5b induced apoptosis via the cleavage of caspase-7 and PARP, and G1 cell cycle arrest via upregulated p21 expression. All these results suggested that A5b was the first dual inhibitor against JMJD3 and HDAC and can be a potential compound for cancer therapy.

A specific JMJD6 inhibitor potently suppresses multiple types of cancers both in vitro and in vivo.

Jumonji C-domain-containing protein 6 (JMJD6), an iron (Fe2+) and α-ketoglutarate (α-KG)-dependent oxygenase, is expressed at high levels, correlated with poor prognosis, and considered as a therapeutic target in multiple cancer types. However, specific JMJD6 inhibitors that are potent in suppressing tumorigenesis have not been reported so far. We herein report that iJMJD6, a specific small-molecule inhibitor of JMJD6 with favorable physiochemical properties, inhibits the enzymatic activity of JMJD6 protein both in vitro and in cultured cells. iJMJD6 is effective in suppressing cell proliferation, migration, and invasion in multiple types of cancer cells in a JMJD6-dependent manner, while it exhibits minimal toxicity in normal cells. Mechanistically, iJMJD6 represses the expression of oncogenes, including Myc and CCND1, in accordance with JMJD6 function in promoting the transcription of these genes. iJMJD6 exhibits suitable pharmacokinetic properties and suppresses tumor growth in multiple cancer cell line- and patient-derived xenograft models safely. Furthermore, combination therapy with iJMJD6 and BET protein inhibitor (BETi) JQ1 or estrogen receptor antagonist fulvestrant exhibits synergistic effects in suppressing tumor growth. Taken together, we demonstrate that inhibition of JMJD6 enzymatic activity by using iJMJD6 is effective in suppressing oncogene expression and cancer development, providing a therapeutic avenue for treating cancers that are dependent on JMJD6 in the clinic.

Novel pharmacological inhibition of JMJD3 improves necrotizing enterocolitis by attenuating the inflammatory response and ameliorating intestinal injury.

Necrotizing enterocolitis (NEC), an acute intestinal inflammatory disease of premature infants, is one of the leading causes of death in neonates. Effective measures for clinical treatment are limited and there is a pressing need in searching for new therapeutic strategies. Jumonji domain-containing protein D3 (JMJD3), a histone H3 lysine 27 (H3K27) demethylase plays a proinflammatory role in sepsis and neuroinflammation. However, whether JMJD3 is involved in the pathogenesis of NEC has not been elucidated. Here we report that overexpressed JMJD3 was revealed in the intestine of NEC patients by bioinformatic analysis. Moreover, upregulated JMJD3 and suppressed H3K27me3 were detected in both NEC patients and neonatal mice subjected to experimental NEC. Importantly, administration of GSK-J4, a specific JMJD3 inhibitor, rescued neonatal mice from NEC-associated lethality by suppressing proinflammatory response with attenuated IL-6, TNF-α, and MCP-1 levels and ameliorating intestinal injury with reversed claudin-1, occludin, and E-cadherin expression. Remarkably, administration of GSK-J4 attenuated intestinal injury by inhibiting activation of intestinal necroptosis in NEC mice. Administration of GSK-J4 regulated intestinal inflammation via NF-κB and JAK2/STAT3 pathway. These results indicate that JMJD3 is involved in the development of NEC and inhibition of JMJD3 overexpression by mean of GSK-J4 could be a potential therapeutic approach in the prevention and treatment of NEC.

The JMJD3 histone demethylase inhibitor GSK-J1 ameliorates lipopolysaccharide-induced inflammation in a mastitis model.

Jumonji domain-containing 3 (JMJD3/KDM6B) is a histone demethylase that plays an important role in regulating development, differentiation, immunity, and tumorigenesis. However, the mechanisms responsible for the epigenetic regulation of inflammation during mastitis remain incompletely understood. Here, we aimed to investigate the role of JMJD3 in the lipopolysaccharide (LPS)-induced mastitis model. GSK-J1, a small molecule inhibitor of JMJD3, was applied to treat LPS-induced mastitis in mice and in mouse mammary epithelial cells in vivo and in vitro. Breast tissues were then collected for histopathology and protein/gene expression examination, and mouse mammary epithelial cells were used to investigate the mechanism of regulation of the inflammatory response. We found that the JMJD3 gene and protein expression were upregulated in injured mammary glands during mastitis. Unexpectedly, we also found JMJD3 inhibition by GSK-J1 significantly alleviated the severity of inflammation in LPS-induced mastitis. These results are in agreement with the finding that GSK-J1 treatment led to the recruitment of histone 3 lysine 27 trimethylation (H3K27me3), an inhibitory chromatin mark, in vitro. Furthermore, mechanistic investigation suggested that GSK-J1 treatment directly interfered with the transcription of inflammatory-related genes by H3K27me3 modification of their promoters. Meanwhile, we also demonstrated that JMJD3 depletion or inhibition by GSK-J1 decreased the expression of toll-like receptor 4 and negated downstream NF-κB proinflammatory signaling and subsequently reduced LPS-stimulated upregulation of Tnfa, Il1b, and Il6. Together, we propose that targeting JMJD3 has therapeutic potential for the treatment of inflammatory diseases.

Effects of GSK-J4 on JMJD3 Histone Demethylase in Mouse Prostate Cancer Xenografts.

BACKGROUND/AIM: Histone methylation status is required to control gene expression. H3K27me3 is an epigenetic tri-methylation modification to histone H3 controlled by the demethylase JMJD3. JMJD3 is dysregulated in a wide range of cancers and has been shown to control the expression of a specific growth-modulatory gene signature, making it an interesting candidate to better understand prostate tumor progression in vivo. This study aimed to identify the impact of JMJD3 inhibition by its inhibitor, GSK4, on prostate tumor growth in vivo. MATERIALS AND METHODS: Prostate cancer cell lines were implanted into Balb/c nude male mice. The effects of the selective JMJD3 inhibitor GSK-J4 on tumor growth were analyzed by bioluminescence assays and H3K27me3-regulated changes in gene expression were analyzed by ChIP-qPCR and RT-qPCR. RESULTS: JMJD3 inhibition contributed to an increase in tumor growth in androgen-independent (AR-) xenografts and a decrease in androgen-dependent (AR+). GSK-J4 treatment modulated H3K27me3 enrichment on the gene panel in DU-145-luc xenografts while it had little effect on PC3-luc and no effect on LNCaP-luc. Effects of JMJD3 inhibition affected the panel gene expression. CONCLUSION: JMJD3 has a differential effect in prostate tumor progression according to AR status. Our results suggest that JMJD3 is able to play a role independently of its demethylase function in androgen-independent prostate cancer. The effects of GSK-J4 on AR+ prostate xenografts led to a decrease in tumor growth.

Inhibition of histone demethylase KDM4 by ML324 induces apoptosis through the unfolded protein response and Bim upregulation in hepatocellular carcinoma cells.

Hepatocellular carcinoma (HCC) is an extremely aggressive malignancy that ranks as the sixth-leading cause of cancer-associated death worldwide. Recently, various epigenetic mechanisms including gene methylation were reported to be potential next era HCC therapeutics and biomarkers. Although inhibition of epigenetic enzymes including histone lysine demethylase 4 (KDM4) enhanced cell death in HCC cells, the detailed mechanism of cell death machinery is poorly understood. In this study, we found that ML324, a small molecule KDM4-specific inhibitor, induced the death of HCC cells in a general cell culture system and 3D spheroid culture with increased cleavage of caspase-3. Mechanistically, we identified that unfolded protein responses (UPR) were involved in ML324-induced HCC cell death. Incubation of HCC cells with ML324 upregulated death receptor 5 (DR5) expression through the activation transcription factor 3 (ATF3)-C/EBP homologous protein (CHOP)-dependent pathway. Moreover, we identified BIM protein as a mediator of ML324-induced apoptosis using CRISPR/Cas9 knockout analysis. We showed that the loss of Bim suppressed ML324-induced apoptosis by flow cytometry analysis, colony formation assay, and caspase-3 activation assay. Interestingly, BIM protein expression by ML324 was regulated by ATF3, CHOP, and DR5 which are factors involved in UPR. Specifically, we confirmed the regulating roles of KDM4E in Bim and CHOP expression using a chromatin immune precipitation (ChIP) assay. Physical binding of KDM4E to Bim and CHOP promoters decreased the response to ML324. Our findings suggest that KDM4 inhibition is a potent anti-tumor therapeutic strategy for human HCC, and further studies of UPR-induced apoptosis and the associated epigenetic functional mechanisms may lead to the discovery of novel target for future cancer therapy.

Inhibition of JMJD6 by 2-Oxoglutarate Mimics.

Studies on the inhibition of the human 2-oxoglutarate dependent oxygenase JMJD6, which is a cancer target, by 2-oxoglutarate mimics / competitors, including human drugs, drug candidates, and metabolites relevant to cancer are described. JMJD6 assays employed NMR to monitor inhibitor binding and use of mass spectrometry to monitor JMJD6-catalysed lysine hydroxylation. Notably, some clinically applied prolyl hydroxylase inhibitors also inhibit JMJD6. The results will help enable the development of inhibitors selective for human oxygenases, including JMJD6.

Inhibition of Jumonji demethylases reprograms severe dilated cardiomyopathy and prolongs survival.

Hypertrophic/dilated cardiomyopathy, often a prequel to heart failure, is accompanied by maladaptive transcriptional changes that contribute to arrythmias and contractile misfunction. Transgenic mice constitutively expressing high levels of calcineurin are known to develop extreme heart hypertrophy, which progresses to dilated cardiomyopathy, and to die several weeks after birth. Here, we characterized aberrant transcriptional and epigenetic pathways in this mouse model and established a pharmacological approach to treat established cardiomyopathy. We found that H3K4me3 (trimethyl histone 3 lysine 4) and H3K9me3 (trimethyl histone 3 lysine 9) Jumonji histone demethylases are markedly increased at the protein level and show enhanced enzymatic activity in diseased hearts. These epigenetic regulators continued to increase with time, further affecting cardiac gene expression. Our findings parallel the lower H3K4me3 and H3K9me3 levels seen in human patients. Inhibition of Jumonji demethylase activities in vivo results in lower histone demethylase enzymatic function in the heart and higher histone methylation levels and leads to partial reduction of heart size, reversal of maladaptive transcriptional programs, improved heart function, and prolonged survival. At the molecular level, target genes of transcription factor myocyte enhancer factor 2 are specifically regulated in response to pharmacological or genetic inhibition of Jumonji demethylases. Similar transcriptional reversal of disease-associated genes is seen in a second disease model based on cardiac mechanical overload. Our findings validate pharmacological inhibitors of Jumonji demethylases as potential therapeutics for the treatment of cardiomyopathies across disease models and provide evidence of the reversal of maladaptive transcriptional reprogramming leading to partial restoration of cardiac function. In addition, this study defines pathways of therapeutic resistance upregulated with disease progression.

A protocol for high-throughput screening of histone lysine demethylase 4 inhibitors using TR-FRET assay.

Identification of diverse chemotypes of selective KDM4 inhibitors is important for exploring and validating the roles of KDM4s in the pathogenesis of human disease and for developing therapies. Here, we report a protocol for high-throughput screening of KDM4 inhibitors using TR-FRET demethylation functional assay. We describe this protocol for screen of KDM4B inhibitors, which can be modified to screen inhibitors of other JmjC-domain-containing KDMs. For complete details on the use and execution of this protocol, please refer to Singh et al. (2021).

Enhanced Properties of a Benzimidazole Benzylpyrazole Lysine Demethylase Inhibitor: Mechanism-of-Action, Binding Site Analysis, and Activity in Cellular Models of Prostate Cancer.

Jumonji domain-containing lysine demethylase (KDM) enzymes are encoded by genes of the KDM superfamily. Activities of the KDM4 subfamily promote aggressive phenotypes associated with prostate cancer (PCa). Previously, we discovered a benzimidazole pyrazole molecule that inhibited KDM4 isoforms with properties tractable for development. Here, we demonstrate that a benzyl-substituted variant of this inhibitor exhibits improved potency in biochemical assays, is cell-permeable, and kills PCa cells at low micromolar concentrations. By X-ray crystallography and kinetics-based assays, we demonstrate that the mechanism of inhibition is complex, proceeding via competition with the enzyme for binding of active-site Fe2+ and by populating a distal site on the enzyme surface. Furthermore, we provide evidence that the inhibitor's cytostatic properties arise from direct intracellular inhibition of KDM4 enzymes. PCa cells treated with the inhibitor exhibit reduced expression of genes regulated by the androgen receptor, an outcome accompanied by epigenetic maintenance of a heterochromatic state.

Histone modification of pain-related gene expression in spinal cord neurons under a persistent postsurgical pain-like state by electrocautery.

Chronic postsurgical pain (CPSP) is a serious problem. We developed a mouse model of CPSP induced by electrocautery and examined the mechanism of CPSP. In this mouse model, while both incision and electrocautery each produced acute allodynia, persistent allodynia was only observed after electrocautery. Under these conditions, we found that the mRNA levels of Small proline rich protein 1A (Sprr1a) and Annexin A10 (Anxa10), which are the key modulators of neuropathic pain, in the spinal cord were more potently and persistently increased by electrocautery than by incision. Furthermore, these genes were overexpressed almost exclusively in chronic postsurgical pain-activated neurons. This event was associated with decreased levels of tri-methylated histone H3 at Lys27 and increased levels of acetylated histone H3 at Lys27 at their promoter regions. On the other hand, persistent allodynia and overexpression of Sprr1a and Anxa10 after electrocautery were dramatically suppressed by systemic administration of GSK-J4, which is a selective H3K27 demethylase inhibitor. These results suggest that the effects of electrocautery contribute to CPSP along with synaptic plasticity and epigenetic modification.

Pharmacological Inhibition of Core Regulatory Circuitry Liquid-liquid Phase Separation Suppresses Metastasis and Chemoresistance in Osteosarcoma.

Liquid-liquid phase-separated (LLPS) transcriptional factor assemblies at super-enhancers (SEs) provide a conceptual framework for underlying transcriptional control in mammal cells. However, the mechanistic understanding of LLPS in aberrant transcription driven by dysregulation of SEs in human malignancies is still elusive. By integrating SE profiling and core regulatory circuitry (CRC) calling algorithm, the CRC of metastatic and chemo-resistant osteosarcoma is delineated. CRC components, HOXB8 and FOSL1, produce dense and dynamic phase-separated droplets in vitro and liquid-like puncta in cell nuclei. Disruption of CRC phase separation decreases the chromatin accessibility in SE regions and inhibits the release of RNA polymerase II from the promoter of SE-driven genes. Importantly, absence of CRC key component causes a reduction in osteosarcoma tumor growth and metastasis. Moreover, it is shown that CRC condensates can be specifically attenuated by the H3K27 demethylase inhibitor, GSK-J4. Pharmacological inhibition of the CRC phase separation results in metastasis suppression and re-sensitivity to chemotherapy drugs in patient-derived xenograft model. Taken together, this study reveals a previously unknown mechanism that CRC factors formed LLPS condensates, and provides a phase separation-based pharmacological strategy to target undruggable CRC components for the treatment of metastatic and chemo-resistant osteosarcoma.

SMARCA4 deficient tumours are vulnerable to KDM6A/UTX and KDM6B/JMJD3 blockade.

Despite the genetic inactivation of SMARCA4, a core component of the SWI/SNF-complex commonly found in cancer, there are no therapies that effectively target SMARCA4-deficient tumours. Here, we show that, unlike the cells with activated MYC oncogene, cells with SMARCA4 inactivation are refractory to the histone deacetylase inhibitor, SAHA, leading to the aberrant accumulation of H3K27me3. SMARCA4-mutant cells also show an impaired transactivation and significantly reduced levels of the histone demethylases KDM6A/UTX and KDM6B/JMJD3, and a strong dependency on these histone demethylases, so that its inhibition compromises cell viability. Administering the KDM6 inhibitor GSK-J4 to mice orthotopically implanted with SMARCA4-mutant lung cancer cells or primary small cell carcinoma of the ovary, hypercalcaemic type (SCCOHT), had strong anti-tumour effects. In this work we highlight the vulnerability of KDM6 inhibitors as a characteristic that could be exploited for treating SMARCA4-mutant cancer patients.