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EZH2 is a mediator of EWS/FLI1 driven tumor growth and metastasis blocking endothelial and neuro-ectodermal differentiation.

ABSTRACT: Ewing tumors (ET) are highly malignant, localized in bone or soft tissue, and are molecularly defined by ews/ets translocations. DNA microarray analysis revealed a relationship of ET to both endothelium and fetal neural crest. We identified expression of histone methyltransferase enhancer of Zeste, Drosophila, Homolog 2 (EZH2) to be increased in ET. Suppressive activity of EZH2 maintains stemness in normal and malignant cells. Here, we found EWS/FLI1 bound to the EZH2 promoter in vivo, and induced EZH2 expression in ET and mesenchymal stem cells. Down-regulation of EZH2 by RNA interference in ET suppressed oncogenic transformation by inhibiting clonogenicity in vitro. Similarly, tumor development and metastasis was suppressed in immunodeficient Rag2(-/-)gamma(C)(-/-) mice. EZH2-mediated gene silencing was shown to be dependent on histone deacetylase (HDAC) activity. Subsequent microarray analysis of EZH2 knock down, HDAC-inhibitor treatment and confirmation in independent assays revealed an undifferentiated phenotype maintained by EZH2 in ET. EZH2 regulated stemness genes such as nerve growth factor receptor (NGFR), as well as genes involved in neuroectodermal and endothelial differentiation (EMP1, EPHB2, GFAP, and GAP43). These data suggest that EZH2 might have a central role in ET pathology by shaping the oncogenicity and stem cell phenotype of this tumor.

SUBMITTER: Richter GH

PROVIDER: S-EPMC2656557 | biostudies-literature |

REPOSITORIES: biostudies-literature

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EZH2 is a mediator of EWS-FLI1 driven tumor growth blocking endothelial and neuro-ectodermal differentiation

Project description:Ewing Tumors (ET) are highly malignant tumors, localized in bone or soft tissue and are molecularly defined by ews/ets translocations. We identified histone methyl-transferase Enhancer of Zeste, Drosophila, Homolog 2 (EZH2) to be increased in ET. EZH2’s suppressive activity maintains stemness in normal and malignant cells. Here we found EZH2 to be upregulated by the pathognomonic fusion oncogene EWS-FLI1 in ET and mesenchymal stem cells. Downregulation of EZH2 by RNA interference in ET suppressed oncogenic transformation by inhibiting clonogenicity in vitro. Similarly, tumor development and metastasis in immunodeficient Rag2-/-γC-/- mice was suppressed. EZH2-mediated gene silencing was shown to be dependent on histone deacetylase (HDAC) activity. Subsequent microarray analysis of EZH2 knock down, HDAC-inhibitor treatment and confirmation in independent assays revealed an undifferentiated phenotype maintained by EZH2 in ET. Downregulation of EZH2 decreased histone H3 lysine 27 trimethylation (H3K27me3) at target loci. EZH2 regulated stemness genes such as nerve growth factor receptor (NGFR) as well as genes involved in neuroectodermal differentiation (EMP1, EPHB2, GFAP, GAP43). These data suggest that EZH2 might play a central role in Ewing Tumor pathology shaping the oncogenicity and stem cell phenotype of this tumor presumably by epigenetic regulation.

2008-10-01 | GSE12692 | GEO

RNAi profiling of human ezh2 specific siRNA A673 treated cells reveals EZh2 is a mediator of EWS-FLI1 driven tumor growth blocking endothelial and neuro-ectodermal differentiation

Project description:Ewing Tumors (ET) are highly malignant tumors, localized in bone or soft tissue and are molecularly defined by ews/ets translocations. We identified histone methyl-transferase Enhancer of Zeste, Drosophila, Homolog 2 (EZH2) to be increased in ET. EZH2âs suppressive activity maintains stemness in normal and malignant cells. Here we found EZH2 to be upregulated by the pathognomonic fusion oncogene EWS-FLI1 in ET and mesenchymal stem cells. Downregulation of EZH2 by RNA interference in ET suppressed oncogenic transformation by inhibiting clonogenicity in vitro. Similarly, tumor development and metastasis in immunodeficient Rag2-/-Î³C-/- mice was suppressed. EZH2-mediated gene silencing was shown to be dependent on histone deacetylase (HDAC) activity. Subsequent microarray analysis of EZH2 knock down, HDAC-inhibitor treatment and confirmation in independent assays revealed an undifferentiated phenotype maintained by EZH2 in ET. Downregulation of EZH2 decreased histone H3 lysine 27 trimethylation (H3K27me3) at target loci. EZH2 regulated stemness genes such as nerve growth factor receptor (NGFR) as well as genes involved in neuroectodermal differentiation (EMP1, EPHB2, GFAP, GAP43). These data suggest that EZH2 might play a central role in Ewing Tumor pathology shaping the oncogenicity and stem cell phenotype of this tumor presumably by epigenetic regulation. Experiment Overall Design: A673 cells were treated for 24 hours either with 100 nM Trichostatin A (TSA) or 0.01% DMSO. In siRNA experiments with ezh2 specific siRNA A673 cells were resuspended in medium containing 5 nM siRNA and transfection reagent and incubated for 48 hours. RNA from cells under such treatment was isolated with Trizol and subjected to microarray analysis onto human U133A microarray following the Affymetrix protocol.

2008-10-26 | E-GEOD-12692 | biostudies-arrayexpress

GLI1 is a central mediator of EWS/FLI1 signaling in Ewing tumors.

Project description:The Ewing Sarcoma Family Tumors (ESFT) consist of the classical pathologic entities of Ewing Sarcoma and peripheral Primitive Neuroectodermal Tumor. Occurring largely in the childhood through young adult years, these tumors have an unsurpassed propensity for metastasis and have no defined cell of origin. The biology of these aggressive malignancies centers around EWS/FLI1 and related EWS/ETS chimeric transcription factors, which are largely limited to this tumor class. Much progress has been made in the identification of a network of loci whose expression is modulated by EWS/FLI1 and its congeners. To date, little progress has been made in reconstructing the sequence of direct and indirect events that produce this network of modulated loci. The recent identification of GLI1 as an upregulated target of EWS/ETS transcription factors suggests a target which may be a more central mediator in the ESFT signaling network. In this paper, we further define the relationship of EWS/FLI1 expression and GLI1 upregulation in ESFT. This relationship is supported with data from primary tumor specimens. It is consistently observed across multiple ESFT cell lines and with multiple means of EWS/FLI1 inhibition. GLI1 inhibition affects tumor cell line phenotype whether shRNA or endogenous or pharmacologic inhibitors are employed. As is seen in model transformation systems, GLI1 upregulation by EWS/FLI1 appears to be independent of Hedgehog stimulation. Consistent with a more central role in ESFT pathogenesis, several known EWS/FLI1 targets appear to be targeted through GLI1. These findings further establish a central role for GLI1 in the pathogenesis of Ewing Tumors.

| S-EPMC2763206 | biostudies-literature

EWS-FLI1 impairs aryl hydrocarbon receptor activation by blocking tryptophan breakdown via the kynurenine pathway.

Project description:Ewing sarcoma (ES) is an aggressive pediatric tumor driven by the fusion protein EWS-FLI1. We report that EWS-FLI1 suppresses TDO2-mediated tryptophan (TRP) breakdown in ES cells. Gene expression and metabolite analyses reveal an EWS-FLI1-dependent regulation of TRP metabolism. TRP consumption increased in the absence of EWS-FLI1, resulting in kynurenine and kynurenic acid accumulation, both aryl hydrocarbon receptor (AHR) ligands. Activated AHR binds to the promoter region of target genes. We demonstrate that EWS-FLI1 knockdown results in AHR nuclear translocation and activation. Our data suggest that EWS-FLI1 suppresses autocrine AHR signaling by inhibiting TDO2-catalyzed TRP breakdown.

| S-EPMC4988508 | biostudies-literature

A small molecule blocking oncogenic protein EWS-FLI1 interaction with RNA helicase A inhibits growth of Ewing's sarcoma.

Project description:Many sarcomas and leukemias carry nonrandom chromosomal translocations encoding tumor-specific mutant fusion transcription factors that are essential to their molecular pathogenesis. Ewing's sarcoma family tumors (ESFTs) contain a characteristic t(11;22) translocation leading to expression of the oncogenic fusion protein EWS-FLI1. EWS-FLI1 is a disordered protein that precludes standard structure-based small-molecule inhibitor design. EWS-FLI1 binding to RNA helicase A (RHA) is important for its oncogenic function. We therefore used surface plasmon resonance screening to identify compounds that bind EWS-FLI1 and might block its interaction with RHA. YK-4-279, a derivative of the lead compound from the screen, blocks RHA binding to EWS-FLI1, induces apoptosis in ESFT cells and reduces the growth of ESFT orthotopic xenografts. These findings provide proof of principle that inhibiting the interaction of mutant cancer-specific transcription factors with the normal cellular binding partners required for their oncogenic activity provides a promising strategy for the development of uniquely effective, tumor-specific anticancer agents.

| S-EPMC2777681 | biostudies-literature

Blocking immunosuppressive neutrophils deters pY696-EZH2-driven brain metastases.

Project description:The functions of immune cells in brain metastases are unclear because the brain has traditionally been considered "immune privileged." However, we found that a subgroup of immunosuppressive neutrophils is recruited into the brain, enabling brain metastasis development. In brain metastatic cells, enhancer of zeste homolog 2 (EZH2) is highly expressed and phosphorylated at tyrosine-696 (pY696)-EZH2 by nuclear-localized Src tyrosine kinase. Phosphorylation of EZH2 at Y696 changes its binding preference from histone H3 to RNA polymerase II, which consequently switches EZH2's function from a methyltransferase to a transcription factor that increases c-JUN expression. c-Jun up-regulates protumorigenic inflammatory cytokines, including granulocyte colony-stimulating factor (G-CSF), which recruits Arg1+- and PD-L1+ immunosuppressive neutrophils into the brain to drive metastasis outgrowth. G-CSF-blocking antibodies or immune checkpoint blockade therapies combined with Src inhibitors impeded brain metastasis in multiple mouse models. These findings indicate that pY696-EZH2 can function as a methyltransferase-independent transcription factor to facilitate the brain infiltration of immunosuppressive neutrophils, which could be clinically targeted for brain metastasis treatment.

| S-EPMC7948522 | biostudies-literature

Targeted Therapy for EWS-FLI1 in Ewing Sarcoma.

Project description:Ewing sarcoma (EwS) is a rare and predominantly pediatric malignancy of bone and soft tissue in children and adolescents. Although international collaborations have greatly improved the prognosis of most EwS, the occurrence of macrometastases or relapse remains challenging. The prototypic oncogene EWS-FLI1 acts as an aberrant transcription factor that drives the cellular transformation of EwS. In addition to its involvement in RNA splicing and the DNA damage response, this chimeric protein directly binds to GGAA repeats, thereby modifying the transcriptional profile of EwS. Direct pharmacological targeting of EWS-FLI1 is difficult because of its intrinsically disordered structure. However, targeting the EWS-FLI1 protein complex or downstream pathways provides additional therapeutic options. This review describes the EWS-FLI1 protein partners and downstream pathways, as well as the related target therapies for the treatment of EwS.

| S-EPMC10452796 | biostudies-literature

EWS-FLI1-targeting peptide identifies Ewing sarcoma tumor boundaries and lymph node metastasis via near-infrared imaging.

Project description:Ewing sarcoma (ES) is one of the most aggressive types of pediatric tumors. The lack of tools for the identification of ES has largely hindered clinical diagnosis and the improvement of treatment. To address this challenge, we synthesized a near-infrared (NIR) fluorescent probe (CS2-N-E9R) that targets the ES-specific fusion protein EWS-FLI1 (E/F). This probe exhibited specific and high binding affinity to E/F. Further studies in animal models showed that CS2-N-E9R can be used to identify the boundaries of ES and lymph node metastases under a complex biological environment. These results demonstrate that CS2-N-E9R is a promising probe for early diagnosis and surgical guidance of ES through molecularly targeted NIR imaging.

| S-EPMC8637573 | biostudies-literature

A polypeptide from the junction region sequence of EWS-FLI1 inhibits Ewing's sarcoma cells, interacts with the EWS-FLI1 and partner proteins.

Project description:The EWS-FLI1 chimeric protein uniquely expressed in Ewing's sarcoma has an obligate role in its aetiology. In our previous report we showed that ectopic expression of the DNA sequences form the junction region (a.a 251-280) can inhibit Ewing's sarcoma cell growth. In the present report, we introduced a peptide (TAT/NLS/EWS-PEP) comprising of thirty amino acids spanning the junction in conjunction with HIV-1-trans-activating (TAT) and nuclear localization signal sequence (NLS). Peptide uptake and localization studies revealed presence of peptide in ~99% of transduced cells and in the nucleus. Peptide transfection induced cytotoxicity relative to untreated and TAT-NLS peptide treated Ewing's sarcoma cells. The peptide inhibited clonogenicity, cell cycle, bromo-deoxy uridine (BrdU) uptake and invasion capacity of treated cells. The treatment also affected epithelial to mesenchymal transition (EMT) markers and EWS-FLI1 target gene expression levels. Co-immunoprecipitation experiments involving ectopically expressed full-length EWS-FLI1 protein and the peptide revealed an interaction. Additionally, we found that peptide interaction also occurs with the protein-GGAA microsatellite sequences complex known to contain EWS-FLI1. Further, in the pull-down assay, the peptide was found to interact with proteins known to potentially interact with EWS-FLI1. Based on these results we conclude that peptide could be applied in targeting EWS-FLI1 protein.

| S-EPMC5543137 | biostudies-literature

USP19 deubiquitinates EWS-FLI1 to regulate Ewing sarcoma growth.

Project description:Ewing sarcoma is the second most common pediatric bone and soft tissue tumor presenting with an aggressive behavior and prevalence to metastasize. The diagnostic translocation t(22;11)(q24;12) leads to expression of the chimeric oncoprotein EWS-FLI1 which is uniquely expressed in all tumor cells and maintains their survival. Constant EWS-FLI1 protein turnover is regulated by the ubiquitin proteasome system. Here, we now identified ubiquitin specific protease 19 (USP19) as a regulator of EWS-FLI1 stability using an siRNA based screening approach. Depletion of USP19 resulted in diminished EWS-FLI1 protein levels and, vice versa, upregulation of active USP19 stabilized the fusion protein. Importantly, stabilization appears to be specific for the fusion protein as it could not be observed neither for EWSR1 nor for FLI1 wild type proteins even though USP19 binds to the N-terminal EWS region to regulate deubiquitination of both EWS-FLI1 and EWSR1. Further, stable shUSP19 depletion resulted in decreased cell growth and diminished colony forming capacity in vitro, and significantly delayed tumor growth in vivo. Our findings not only provide novel insights into the importance of the N-terminal EWSR1 domain for regulation of fusion protein stability, but also indicate that inhibition of deubiquitinating enzyme(s) might constitute a novel therapeutic strategy in treatment of Ewing sarcoma.

| S-EPMC6353870 | biostudies-literature

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