RESUMO
Alterations in transcriptional regulators can orchestrate oncogenic gene expression programs in cancer. Here, we show that the BRG1/BRM-associated factor (BAF) chromatin remodeling complex, which is mutated in over 20% of human tumors, interacts with EWSR1, a member of a family of proteins with prion-like domains (PrLD) that are frequent partners in oncogenic fusions with transcription factors. In Ewing sarcoma, we find that the BAF complex is recruited by the EWS-FLI1 fusion protein to tumor-specific enhancers and contributes to target gene activation. This process is a neomorphic property of EWS-FLI1 compared to wild-type FLI1 and depends on tyrosine residues that are necessary for phase transitions of the EWSR1 prion-like domain. Furthermore, fusion of short fragments of EWSR1 to FLI1 is sufficient to recapitulate BAF complex retargeting and EWS-FLI1 activities. Our studies thus demonstrate that the physical properties of prion-like domains can retarget critical chromatin regulatory complexes to establish and maintain oncogenic gene expression programs.
Assuntos
Proteínas de Ligação a Calmodulina/química , Proteínas de Ligação a Calmodulina/metabolismo , Proteínas de Fusão Oncogênica/metabolismo , Proteína Proto-Oncogênica c-fli-1/metabolismo , Proteína EWS de Ligação a RNA/metabolismo , Proteínas de Ligação a RNA/química , Proteínas de Ligação a RNA/metabolismo , Sarcoma de Ewing/genética , Linhagem Celular Tumoral , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Humanos , Células-Tronco Mesenquimais/metabolismo , Repetições de Microssatélites , Complexos Multiproteicos/química , Complexos Multiproteicos/metabolismo , Proteínas Nucleares/química , Proteínas Nucleares/metabolismo , Proteínas Priônicas/metabolismo , Domínios Proteicos , Sarcoma de Ewing/patologiaRESUMO
Gene activation by mammalian transcription factors (TFs) requires multivalent interactions of their low-complexity domains (LCDs), but how such interactions regulate transcription remains unclear. It has been proposed that extensive LCD-LCD interactions culminating in liquid-liquid phase separation (LLPS) of TFs is the dominant mechanism underlying transactivation. Here, we investigated how tuning the amount and localization of LCD-LCD interactions in vivo affects transcription of endogenous human genes. Quantitative single-cell and single-molecule imaging reveals that the oncogenic TF EWS::FLI1 requires a narrow optimum of LCD-LCD interactions to activate its target genes associated with GGAA microsatellites. Increasing LCD-LCD interactions toward putative LLPS represses transcription of these genes in patient-derived cells. Likewise, ectopically creating LCD-LCD interactions to sequester EWS::FLI1 into a well-documented LLPS compartment, the nucleolus, inhibits EWS::FLI1-driven transcription and oncogenic transformation. Our findings show how altering the balance of LCD-LCD interactions can influence transcriptional regulation and suggest a potential therapeutic strategy for targeting disease-causing TFs.
Assuntos
Sarcoma de Ewing , Animais , Carcinogênese/genética , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica , Humanos , Mamíferos/metabolismo , Proteínas de Fusão Oncogênica/genética , Proteínas de Fusão Oncogênica/metabolismo , Proteína Proto-Oncogênica c-fli-1/genética , Proteína Proto-Oncogênica c-fli-1/metabolismo , Sarcoma de Ewing/tratamento farmacológico , Sarcoma de Ewing/genética , Ativação Transcricional/genéticaRESUMO
Various types of repetitive sequences are dysregulated in cancer. In Ewing sarcoma, the oncogenic fusion protein EWS-FLI1 induces chromatin features typical of active enhancers at GGAA microsatellite repeats, but the function of these sites has not been directly demonstrated. Here, by combining nascent transcription profiling with epigenome editing, we found that a subset of GGAA microsatellite repeats is transcriptionally active in Ewing sarcoma and that silencing individual repeats abolishes local nascent transcription and leads to markedly reduced expression of putative target genes. Epigenome silencing of these repeat sites does not affect gene expression in unrelated cells, can prevent the induction of gene expression by EWS-FLI1, and, in the case of a GGAA repeat that controls SOX2 expression from a distance of 470 kb, is sufficient to impair the growth of Ewing sarcoma xenografts. Using an experimental approach that is broadly applicable to testing different types of repetitive genomic elements, our study directly demonstrates that specific repeat microsatellites can have critical gene regulation functions in cancer and thus represent tumor-specific vulnerabilities that may be exploited to develop new therapies.
Assuntos
Neoplasias Ósseas/genética , Elementos Facilitadores Genéticos , Regulação Neoplásica da Expressão Gênica , Inativação Gênica , Repetições de Microssatélites , Proteínas de Fusão Oncogênica/metabolismo , Proteína Proto-Oncogênica c-fli-1/metabolismo , Proteína EWS de Ligação a RNA/metabolismo , Sarcoma de Ewing/genética , Animais , Neoplasias Ósseas/metabolismo , Neoplasias Ósseas/patologia , Células Cultivadas , Cromatina/metabolismo , Proteína Homeobox Nkx-2.2 , Proteínas de Homeodomínio/biossíntese , Proteínas de Homeodomínio/genética , Humanos , Células-Tronco Mesenquimais/metabolismo , Camundongos , RNA não Traduzido/biossíntese , Sarcoma de Ewing/metabolismo , Sarcoma de Ewing/patologia , Fatores de Transcrição/biossíntese , Fatores de Transcrição/genética , Transcrição Gênica , Células Tumorais Cultivadas , Proteínas de Peixe-ZebraRESUMO
Dysregulation of repetitive elements has been implicated in many cancers and other human diseases; however, the role of repetitive elements remains largely unexplored. In this issue of Genes & Development, Boulay and colleagues (pp. 1008-1019) explore the ability of GGAA repeats to act as alternative enhancers activated by EWS-FLI1 in Ewing sarcoma and contribute to tumorigenesis. Using CRISPR-mediated epigenome editing, repression of EWS-FLI1 targeted microsatellite enhancers halted aberrant gene expression and impaired the growth of Ewing sarcoma xenografts in vivo. The study reveals the regulatory capacity of repetitive elements in cancer and offers insight into therapeutic targets for Ewing sarcoma.
Assuntos
Regulação Neoplásica da Expressão Gênica , Sarcoma de Ewing/genética , Linhagem Celular Tumoral , Transformação Celular Neoplásica , Humanos , Repetições de Microssatélites , Proteínas de Fusão Oncogênica/genéticaRESUMO
Primary pulmonary Ewing sarcoma (PES) is a rare malignancy with only sporadic cases reported in the scientific literature. We performed a systematic review of the cases published in the last decade on PubMed, with the aim to describe the clinical, pathological, therapeutic, and prognostic data of PES. Forty-two articles reporting on 50 cases have been reviewed. Globally, 60 % of the patients were males, and the mean age at diagnosis was 30.5 years, with only a few cases diagnosed after 50 years of age. The most common clinical manifestations at diagnosis were dyspnea, cough and chest pain. The most common immunohistochemistry findings were staining for CD99 and (less frequently) for vimentin, and no staining for TTF-1, cytokeratin, desmin and S-100. ESWR1-FL1 translocation was tested in less than half of the cases. The disease was often locally advanced, treated generally with multidisciplinary treatment combining surgery, chemotherapy and radiation therapy. Among patients with follow-up data, approximately 40 % were dead at the time of publication, with the median survival being 11.5 months. Among those who were alive, only 8.3 % was free from disease at 48 months from diagnosis.
Assuntos
Neoplasias Ósseas , Sarcoma de Ewing , Masculino , Humanos , Adulto , Feminino , Sarcoma de Ewing/diagnóstico , Sarcoma de Ewing/terapia , Sarcoma de Ewing/patologia , Imuno-Histoquímica , Prognóstico , Proteínas S100 , Pulmão/patologia , Proteína EWS de Ligação a RNARESUMO
Despite their clonal origins, tumors eventually develop into complex communities made up of phenotypically different cell subpopulations, according to mounting evidence. Tumor cell-intrinsic programming and signals from geographically and temporally changing microenvironments both contribute to this variability. Furthermore, the mutational load is typically lacking in childhood malignancies of adult cancers, and they still exhibit high cellular heterogeneity levels largely mediated by epigenetic mechanisms. Ewing sarcomas represent highly aggressive malignancies affecting both bone and soft tissue, primarily afflicting adolescents. Unfortunately, the outlook for patients facing relapsed or metastatic disease is grim. These tumors are primarily fueled by a distinctive fusion event involving an FET protein and an ETS family transcription factor, with the most prevalent fusion being EWS/FLI1. Despite originating from a common driver mutation, Ewing sarcoma cells display significant variations in transcriptional activity, both within and among tumors. Recent research has pinpointed distinct fusion protein activities as a principal source of this heterogeneity, resulting in markedly diverse cellular phenotypes. In this review, we aim to characterize the role of the EWS/FLI fusion protein in Ewing sarcoma by exploring its general mechanism of activation and elucidating its implications for tumor heterogeneity. Additionally, we delve into potential therapeutic opportunities to target this aberrant fusion protein in the context of Ewing sarcoma treatment.
Assuntos
Neoplasias Ósseas , Sarcoma de Ewing , Adolescente , Adulto , Humanos , Neoplasias Ósseas/terapia , Neoplasias Ósseas/tratamento farmacológico , Linhagem Celular Tumoral , Epigênese Genética , Regulação Neoplásica da Expressão Gênica , Proteínas de Fusão Oncogênica/genética , Proteínas de Fusão Oncogênica/metabolismo , Proteínas/metabolismo , Proteína Proto-Oncogênica c-fli-1/genética , Proteína Proto-Oncogênica c-fli-1/metabolismo , Proteína EWS de Ligação a RNA/genética , Proteína EWS de Ligação a RNA/metabolismo , Sarcoma de Ewing/terapia , Sarcoma de Ewing/tratamento farmacológico , Microambiente TumoralRESUMO
The primary oncogenic event in â¼85% of Ewing sarcomas is a chromosomal translocation that generates a fusion oncogene encoding an aberrant transcription factor. The exact genomic breakpoints within the translocated genes, EWSR1 and FLI1, vary; however, in EWSR1, breakpoints typically occur within introns 7 or 8. We previously found that in Ewing sarcoma cells harboring EWSR1 intron 8 breakpoints, the RNA-binding protein HNRNPH1 facilitates a splicing event that excludes EWSR1 exon 8 from the EWS-FLI1 pre-mRNA to generate an in-frame mRNA. Here, we show that the processing of distinct EWS-FLI1 pre-mRNAs by HNRNPH1, but not other homologous family members, resembles alternative splicing of transcript variants of EWSR1 We demonstrate that HNRNPH1 recruitment is driven by guanine-rich sequences within EWSR1 exon 8 that have the potential to fold into RNA G-quadruplex structures. Critically, we demonstrate that an RNA mimetic of one of these G-quadruplexes modulates HNRNPH1 binding and induces a decrease in the growth of an EWSR1 exon 8 fusion-positive Ewing sarcoma cell line. Finally, we show that EWSR1 exon 8 fusion-positive cell lines are more sensitive to treatment with the pan-quadruplex binding molecule, pyridostatin (PDS), than EWSR1 exon 8 fusion-negative lines. Also, the treatment of EWSR1 exon 8 fusion-positive cells with PDS decreases EWS-FLI1 transcriptional activity, reversing the transcriptional deregulation driven by EWS-FLI1. Our findings illustrate that modulation of the alternative splicing of EWS-FLI1 pre-mRNA is a novel strategy for future therapeutics against the EWSR1 exon 8 containing fusion oncogenes present in a third of Ewing sarcoma.
Assuntos
Quadruplex G , Ribonucleoproteínas Nucleares Heterogêneas/metabolismo , Proteínas de Fusão Oncogênica/genética , Proteínas de Fusão Oncogênica/metabolismo , Splicing de RNA , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ligação Proteica , RNA Mensageiro/química , Proteínas de Ligação a RNARESUMO
BACKGROUND: Ewing sarcoma is a malignancy of primitive cells, possibly of mesenchymal origin. It is probable that genetic perturbations other than EWS-FLI1 cooperate with it to produce the tumor. Sequencing studies identified STAG2 mutations in approximately 15% of cases in humans. In the present study, we hypothesize that loss of Stag2 cooperates with EWS-FLI1 in generating sarcomas derived from murine mesenchymal stem cells (MSCs). METHODS: Mice bearing an inducible EWS-FLI1 transgene were crossed to p53-/- mice in pure C57/Bl6 background. MSCs were derived from the bone marrow of the mice. EWS-FLI1 induction and Stag2 knockdown were achieved in vitro by adenovirus-Cre and shRNA-bearing pGIPZ lentiviral infection, respectively. The cells were then treated with ionizing radiation to 10 Gy. Anchorage independent growth in vitro was assessed by soft agar assays. Cellular migration and invasion were evaluated by transwell assays. Cells were injected with Matrigel intramuscularly into C57/Bl6 mice to test for tumor formation. RESULTS: Primary murine MSCs with the genotype EWS-FLI1 p53-/- were resistant to transformation and did not form tumors in syngeneic mice without irradiation. Stag2 inhibition increased the efficiency and speed of sarcoma formation significantly in irradiated EWS-FLI1 p53-/- MSCs. The efficiency of tumor formation was 91% for cells in mice injected with Stag2-repressed cells and 22% for mice receiving cells without Stag2 inhibition (p < .001). Stag2 knockdown reduced survival of mice in Kaplan-Meier analysis (p < .001). It also increased MSC migration and invasion in vitro but did not affect proliferation rate or aneuploidy. CONCLUSION: Loss of Stag2 has a synergistic effect with EWS-FLI1 in the production of sarcomas from murine MSCs, but the mechanism may not relate to increased proliferation or chromosomal instability. Primary murine MSCs are resistant to transformation, and the combination of p53 null mutation, EWS-FLI1, and Stag2 inhibition does not confer immediate conversion of MSCs to sarcomas. Irradiation is necessary in this model, suggesting that perturbations of other genes beside Stag2 and p53 are likely to be essential in the development of EWS-FLI1-driven sarcomas from MSCs.
Assuntos
Proteínas de Ciclo Celular/metabolismo , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Células-Tronco Mesenquimais/metabolismo , Proteínas de Fusão Oncogênica/genética , Proteínas de Fusão Oncogênica/metabolismo , Proteína Proto-Oncogênica c-fli-1/genética , Proteína Proto-Oncogênica c-fli-1/metabolismo , Proteína EWS de Ligação a RNA/genética , Proteína EWS de Ligação a RNA/metabolismo , Animais , Ciclo Celular/genética , Proteínas de Ciclo Celular/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células , Aberrações Cromossômicas , Modelos Animais de Doenças , Expressão Gênica , Genes p53 , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Interferência de RNA , Sarcoma de Ewing/etiologia , Sarcoma de Ewing/metabolismo , Sarcoma de Ewing/patologiaRESUMO
Developmental transcription programs are epigenetically regulated by multi-protein complexes, including the menin- and MLL-containing trithorax (TrxG) complexes, which promote gene transcription by depositing the H3K4me3 activating mark at target gene promoters. We recently reported that in Ewing sarcoma, MLL1 (lysine methyltransferase 2A, KMT2A) and menin are overexpressed and function as oncogenes. Small molecule inhibition of the menin-MLL interaction leads to loss of menin and MLL1 protein expression, and to inhibition of growth and tumorigenicity. Here, we have investigated the mechanistic basis of menin-MLL-mediated oncogenic activity in Ewing sarcoma. Bromouridine sequencing (Bru-seq) was performed to identify changes in nascent gene transcription in Ewing sarcoma cells, following exposure to the menin-MLL interaction inhibitor MI-503. Menin-MLL inhibition resulted in early and widespread reprogramming of metabolic processes. In particular, the serine biosynthetic pathway (SSP) was the pathway most significantly affected by MI-503 treatment. Baseline expression of SSP genes and proteins (PHGDH, PSAT1, and PSPH), and metabolic flux through the SSP were confirmed to be high in Ewing sarcoma. In addition, inhibition of PHGDH resulted in reduced cell proliferation, viability, and tumor growth in vivo, revealing a key dependency of Ewing sarcoma on the SSP. Loss of function studies validated a mechanistic link between menin and the SSP. Specifically, inhibition of menin resulted in diminished expression of SSP genes, reduced H3K4me3 enrichment at the PHGDH promoter, and complete abrogation of de novo serine and glycine biosynthesis, as demonstrated by metabolic tracing studies with 13 C-labeled glucose. These data demonstrate that the SSP is highly active in Ewing sarcoma and that its oncogenic activation is maintained, at least in part, by menin-dependent epigenetic mechanisms involving trithorax complexes. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Assuntos
Neoplasias Ósseas/metabolismo , Metabolismo Energético , Proteínas Proto-Oncogênicas/metabolismo , Sarcoma de Ewing/metabolismo , Serina/biossíntese , Animais , Antineoplásicos/farmacologia , Neoplasias Ósseas/tratamento farmacológico , Neoplasias Ósseas/genética , Neoplasias Ósseas/patologia , Linhagem Celular Tumoral , Proliferação de Células , Metabolismo Energético/efeitos dos fármacos , Metabolismo Energético/genética , Epigênese Genética , Regulação Neoplásica da Expressão Gênica , Histona-Lisina N-Metiltransferase/genética , Histona-Lisina N-Metiltransferase/metabolismo , Humanos , Masculino , Camundongos Nus , Proteína de Leucina Linfoide-Mieloide/genética , Proteína de Leucina Linfoide-Mieloide/metabolismo , Fosfoglicerato Desidrogenase/genética , Fosfoglicerato Desidrogenase/metabolismo , Monoéster Fosfórico Hidrolases/genética , Monoéster Fosfórico Hidrolases/metabolismo , Proteínas Proto-Oncogênicas/genética , Sarcoma de Ewing/tratamento farmacológico , Sarcoma de Ewing/genética , Sarcoma de Ewing/patologia , Transdução de Sinais , Transaminases/genética , Transaminases/metabolismo , Carga Tumoral , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
EWS-FLI1 constitutes an oncogenic transcription factor that plays key roles in Ewing sarcoma development and maintenance. We have recently succeeded in generating an ex vivo mouse model for Ewing sarcoma by introducing EWS-FLI1 into embryonic osteochondrogenic progenitors. The model well recapitulates the biological characteristics, small round cell morphology, and gene expression profiles of human Ewing sarcoma. Here, we clarified the global DNA binding properties of EWS-FLI1 in mouse Ewing sarcoma. GGAA microsatellites were found to serve as binding sites of EWS-FLI1 albeit with less frequency than that in human Ewing sarcoma; moreover, genomic distribution was not conserved between human and mouse. Nevertheless, EWS-FLI1 binding sites within GGAA microsatellites were frequently associated with the histone H3K27Ac enhancer mark, suggesting that EWS-FLI1 could affect global gene expression by binding its target sites. In particular, the Fox transcription factor binding motif was frequently observed within EWS-FLI1 peaks and Foxq1 was identified as the cooperative partner that interacts with the EWS portion of EWS-FLI1. Trib1 and Nrg1 were demonstrated as target genes that are co-regulated by EWS-FLI1 and Foxq1, and are important for cell proliferation and survival of Ewing sarcoma. Collectively, our findings present novel aspects of EWS-FLI1 function as well as the importance of GGAA microsatellites.
Assuntos
Fatores de Transcrição Forkhead/metabolismo , Regulação Neoplásica da Expressão Gênica/genética , Repetições de Microssatélites/genética , Proteínas de Fusão Oncogênica/metabolismo , Proteína Proto-Oncogênica c-fli-1/metabolismo , Proteína EWS de Ligação a RNA/metabolismo , Sarcoma de Ewing/patologia , Animais , Apoptose/genética , Sítios de Ligação/genética , Ciclo Celular/genética , Linhagem Celular Tumoral , Proliferação de Células/genética , Condrogênese/genética , Proteínas de Ligação a DNA/metabolismo , Modelos Animais de Doenças , Células-Tronco Embrionárias/citologia , Transição Epitelial-Mesenquimal/genética , Fatores de Transcrição Forkhead/genética , Histonas/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Camundongos , Neuregulina-1/genética , Proteínas de Fusão Oncogênica/genética , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/genética , Proteína Proto-Oncogênica c-fli-1/genética , Interferência de RNA , RNA Interferente Pequeno/genética , Proteína EWS de Ligação a RNA/genética , Sarcoma de Ewing/genéticaRESUMO
The synthesis and processing of mRNA, from transcription to translation initiation, often requires splicing of intragenic material. The final mRNA composition varies based on proteins that modulate splice site selection. EWS-FLI1 is an Ewing sarcoma (ES) oncoprotein with an interactome that we demonstrate to have multiple partners in spliceosomal complexes. We evaluate the effect of EWS-FLI1 on posttranscriptional gene regulation using both exon array and RNA-seq. Genes that potentially regulate oncogenesis, including CLK1, CASP3, PPFIBP1, and TERT, validate as alternatively spliced by EWS-FLI1. In a CLIP-seq experiment, we find that EWS-FLI1 RNA-binding motifs most frequently occur adjacent to intron-exon boundaries. EWS-FLI1 also alters splicing by directly binding to known splicing factors including DDX5, hnRNP K, and PRPF6. Reduction of EWS-FLI1 produces an isoform of γ-TERT that has increased telomerase activity compared with wild-type (WT) TERT. The small molecule YK-4-279 is an inhibitor of EWS-FLI1 oncogenic function that disrupts specific protein interactions, including helicases DDX5 and RNA helicase A (RHA) that alters RNA-splicing ratios. As such, YK-4-279 validates the splicing mechanism of EWS-FLI1, showing alternatively spliced gene patterns that significantly overlap with EWS-FLI1 reduction and WT human mesenchymal stem cells (hMSC). Exon array analysis of 75 ES patient samples shows similar isoform expression patterns to cell line models expressing EWS-FLI1, supporting the clinical relevance of our findings. These experiments establish systemic alternative splicing as an oncogenic process modulated by EWS-FLI1. EWS-FLI1 modulation of mRNA splicing may provide insight into the contribution of splicing toward oncogenesis, and, reciprocally, EWS-FLI1 interactions with splicing proteins may inform the splicing code.
Assuntos
Processamento Alternativo/genética , Proteínas de Fusão Oncogênica/metabolismo , Proteína Proto-Oncogênica c-fli-1/metabolismo , Proteína EWS de Ligação a RNA/metabolismo , Transdução de Sinais/genética , Processamento Alternativo/efeitos dos fármacos , Sequência de Bases , Linhagem Celular Tumoral , Éxons/genética , Humanos , Indóis , Íntrons/genética , Proteínas de Fusão Oncogênica/genética , Ligação Proteica/efeitos dos fármacos , Isoformas de Proteínas/metabolismo , Proteína Proto-Oncogênica c-fli-1/genética , Processamento Pós-Transcricional do RNA/efeitos dos fármacos , Processamento Pós-Transcricional do RNA/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteína EWS de Ligação a RNA/genética , Sarcoma de Ewing/genética , Sarcoma de Ewing/patologia , Transdução de Sinais/efeitos dos fármacos , Spliceossomos/efeitos dos fármacos , Spliceossomos/metabolismo , Telomerase/metabolismoRESUMO
High-throughput screening of extracts from plants, marine, and micro-organisms led to the identification of the extract from the plant Phyllanthus engleri as the most potent inhibitor of EWS-FLI1 induced luciferase reporter expression. Testing of compounds isolated from this extract in turn led to the identification of Englerin A (EA) as the active constituent of the extract. EA induced both necrosis and apoptosis in Ewing cells subsequent to a G2M accumulation of cells in the cell cycle. It also impacted clonogenic survival and anchorage-independent proliferation while also decreasing the proportion of chemotherapy-resistant cells identified by high ALDH activity. EA also caused a sustained increase in cytosolic calcium levels. EA appears to exert its effect on Ewing cells through a decrease in phosphorylation of EWS-FLI1 and its ability to bind DNA. This effect is mediated, at least in part, through a decrease in the levels of the calcium-dependent protein kinase PKC-ßI after a transient up-regulation.
Assuntos
Apoptose/efeitos dos fármacos , Neoplasias Ósseas/metabolismo , DNA de Neoplasias/metabolismo , Proteínas de Fusão Oncogênica/metabolismo , Proteína Proto-Oncogênica c-fli-1/metabolismo , Proteína EWS de Ligação a RNA/metabolismo , Sarcoma de Ewing/metabolismo , Sesquiterpenos de Guaiano/farmacologia , Aldeído Desidrogenase/genética , Aldeído Desidrogenase/metabolismo , Apoptose/genética , Neoplasias Ósseas/tratamento farmacológico , Neoplasias Ósseas/genética , Neoplasias Ósseas/patologia , Linhagem Celular Tumoral , DNA de Neoplasias/genética , Humanos , Proteínas de Fusão Oncogênica/genética , Fosforilação/efeitos dos fármacos , Fosforilação/genética , Ligação Proteica/efeitos dos fármacos , Proteína Proto-Oncogênica c-fli-1/genética , Proteína EWS de Ligação a RNA/genética , Sarcoma de Ewing/tratamento farmacológico , Sarcoma de Ewing/genética , Sarcoma de Ewing/patologiaRESUMO
BACKGROUND: Even though virtually all patients with Ewing sarcoma achieve a radiographic complete response, up to 30% of patients who present with localized disease and up to 90% of those who present with metastases experience a metastatic disease recurrence, highlighting the inability to identify patients with residual disease at the end of therapy. Up to 95% of Ewing sarcomas carry a driving EWS-ETS translocation that has an intronic breakpoint that is specific to each tumor, and the authors developed a system to quantitatively detect the specific breakpoint DNA fragment in patient plasma. METHODS: The authors used a long-range multiplex polymerase chain reaction (PCR) technique to identify tumor-specific EWS-ETS breakpoints in Ewing sarcoma cell lines, patient-derived xenografts, and patient tumors, and this sequence was used to design tumor-specific primer sets to detect plasma tumor DNA (ptDNA) by droplet digital PCR in xenograft-bearing mice and patients. RESULTS: Tumor-specific breakpoint DNA fragments were detected in the plasma of xenograft-bearing mice, and the signal correlated with tumor burden during primary tumor growth, after surgical resection, and at the time of metastatic disease recurrence. Furthermore, the authors were able to detect the specific breakpoint in plasma DNA obtained from 3 patients with Ewing sarcoma and in 2 patients the authors were able to detect ptDNA when there was radiographically undetectable disease present. CONCLUSIONS: The use of droplet digital PCR to detect tumor-specific EWS-ETS fusion gene breakpoint ptDNA fragments can be developed into a highly personalized biomarker of disease recurrence that can be optimized in animal studies for ultimate use in patients. Cancer 2016;122:3015-3023. © 2016 American Cancer Society.
Assuntos
Biomarcadores Tumorais/genética , Neoplasias Ósseas/diagnóstico , DNA de Neoplasias/genética , Recidiva Local de Neoplasia/diagnóstico , Medicina de Precisão , Sarcoma de Ewing/diagnóstico , Animais , Biomarcadores Tumorais/sangue , Neoplasias Ósseas/sangue , Neoplasias Ósseas/genética , Proteínas de Ligação a Calmodulina/sangue , Proteínas de Ligação a Calmodulina/genética , DNA de Neoplasias/sangue , Regulação Neoplásica da Expressão Gênica , Humanos , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Recidiva Local de Neoplasia/sangue , Recidiva Local de Neoplasia/genética , Estadiamento de Neoplasias , Proteínas de Fusão Oncogênica/genética , Prognóstico , Proto-Oncogene Mas , Proteína Proto-Oncogênica c-fli-1/sangue , Proteína Proto-Oncogênica c-fli-1/genética , Proteína EWS de Ligação a RNA , Proteínas de Ligação a RNA/sangue , Proteínas de Ligação a RNA/genética , Sarcoma de Ewing/sangue , Sarcoma de Ewing/genética , Translocação Genética , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Ewing sarcoma is a cancer of bone and soft tissue in children that is characterized by a chromosomal translocation involving EWS and an Ets family transcription factor, most commonly Fli-1. EWS-Fli-1 fusion accounts for 85% of cases. The growth and survival of Ewing sarcoma cells are critically dependent on EWS-Fli-1. A large body of evidence has established that EWS-Fli-1 functions as a DNA-binding transcription factor that regulates the expression of a number of genes important for cell proliferation and transformation. However, little is known about the biochemical properties of the EWS-Fli-1 protein. We undertook a series of proteomic analyses to dissect the EWS-Fli-1 interactome. Employing a proximity-dependent biotinylation technique, BioID, we identified cation-independent mannose 6-phosphate receptor (CIMPR) as a protein located in the vicinity of EWS-Fli-1 within a cell. CIMPR is a cargo that mediates the delivery of lysosomal hydrolases from the trans-Golgi network to the endosome, which are subsequently transferred to the lysosomes. Further molecular cell biological analyses uncovered a role for lysosomes in the turnover of the EWS-Fli-1 protein. We demonstrate that an mTORC1 active-site inhibitor, torin 1, which stimulates the TFEB-lysosome pathway, can induce the degradation of EWS-Fli-1, suggesting a potential therapeutic approach to target EWS-Fli-1 for degradation.
Assuntos
Lisossomos/metabolismo , Proteínas de Fusão Oncogênica/fisiologia , Proteômica , Proteína Proto-Oncogênica c-fli-1/fisiologia , Proteína EWS de Ligação a RNA/fisiologia , Sarcoma de Ewing/tratamento farmacológico , Biotinilação , Domínio Catalítico , Linhagem Celular Tumoral , Proliferação de Células , Transformação Celular Neoplásica/genética , Regulação Neoplásica da Expressão Gênica , Células HEK293 , Células HeLa , Humanos , Alvo Mecanístico do Complexo 1 de Rapamicina , Complexos Multiproteicos/metabolismo , Proteoma/metabolismo , Sarcoma de Ewing/patologia , Serina-Treonina Quinases TOR/metabolismo , Espectrometria de Massas em Tandem , Fatores de Transcrição/metabolismo , Rede trans-Golgi/metabolismoRESUMO
BACKGROUND: RE1-silencing transcription factor (REST), a neuronal repressor gene, regulates neuronal stem cell differentiation. Ewing sarcoma may originate from neural crest cells. In the current study, the authors investigated whether REST plays a role in the growth of this tumor. METHODS: REST expression was determined by Western blot analysis and reverse transcription-polymerase chain reaction in 3 human Ewing sarcoma cell lines and 7 patient tumor samples. The role of REST in tumor growth and tumor vascular morphology was determined using a Ewing sarcoma xenograft model. Immunofluorescence staining, Hypoxyprobe, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assays were performed to investigate the impact of REST on pericyte marker expression, hypoxia, and apoptosis in vivo. RESULTS: High levels of REST were expressed in all 3 human Ewing sarcoma cell lines and in 6 of the 7 patient tumor samples. Overexpression of EWS-FLI-1 in human mesenchymal stem cells and human neural progenitor cells was found to increase REST expression. Inhibition of EWS-FLI-1 using small interfering RNA decreased REST expression in human Ewing sarcoma cells. Inhibition of REST did not affect EWS-FLI-1, but significantly suppressed tumor growth in vivo, reduced the tumor vessel pericyte markers α- smooth muscle actin (SMA) and desmin, increased hypoxia and apoptosis in tumor tissues, and decreased the expression of delta-like ligand 4 (DLL4) and Hes1. CONCLUSIONS: Inhibition of REST suppressed tumor growth, inhibited pericyte marker expression, and increased tumor hypoxia and apoptosis. Because tumor vessel function has been linked to tumor growth and metastases, REST may be a new therapeutic target in patients with Ewing sarcoma.
Assuntos
Neurônios/metabolismo , Proteínas de Fusão Oncogênica/genética , Proteína Proto-Oncogênica c-fli-1/genética , Proteína EWS de Ligação a RNA/genética , Proteínas Repressoras/biossíntese , Sarcoma de Ewing/genética , Proteínas Adaptadoras de Transdução de Sinal , Animais , Apoptose/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/biossíntese , Proteínas de Ligação ao Cálcio , Diferenciação Celular/genética , Hipóxia Celular/genética , Regulação Neoplásica da Expressão Gênica/genética , Proteínas de Homeodomínio/biossíntese , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/biossíntese , Camundongos , Neurônios/citologia , Proteínas de Fusão Oncogênica/metabolismo , Proteína Proto-Oncogênica c-fli-1/metabolismo , Proteína EWS de Ligação a RNA/metabolismo , Proteínas Repressoras/genética , Sarcoma de Ewing/patologia , Células-Tronco/citologia , Fatores de Transcrição HES-1RESUMO
The neomorphic transcription factor EWS-FLI1 is a key driver of Ewing sarcoma. Ablation of EWS-FLI1 may present a promising therapeutic strategy for this malignancy. Here we found that the deubiquitinase, ubiquitin specific peptidase 9 X-linked (USP9X) stabilizes EWS-FLI1 protein expression in Ewing sarcoma. We show that USP9X binds the ETS domain of EWS-FLI1 in Ewing sarcoma cells and deubiquitinates EWS-FLI1 and that USP9X and EWS-FLI1 protein expression is correlated in clinical Ewing sarcoma specimens. We found that treatment of Ewing sarcoma cells with the USP9X inhibitor WP1130 mediates rapid EWS-FLI1 degradation in vitro and in vivo which coincides with reduced growth of Ewing sarcoma cells and tumors. Our results suggest that USP9X might be a potential therapeutic target to mediate EWS-FLI1 depletion in Ewing sarcoma.
Assuntos
Sarcoma de Ewing , Humanos , Sarcoma de Ewing/tratamento farmacológico , Sarcoma de Ewing/genética , Sarcoma de Ewing/patologia , Linhagem Celular Tumoral , Proteína EWS de Ligação a RNA/genética , Proteína EWS de Ligação a RNA/metabolismo , Proteína Proto-Oncogênica c-fli-1/genética , Proteína Proto-Oncogênica c-fli-1/metabolismo , Proteínas de Fusão Oncogênica/genética , Proteínas de Fusão Oncogênica/metabolismo , Transformação Celular Neoplásica , Regulação Neoplásica da Expressão Gênica , Ubiquitina Tiolesterase/genética , Ubiquitina Tiolesterase/metabolismoRESUMO
OBJECTIVE: EWS-FLI1 is the most common oncogenic fusion protein in Ewing's sarcoma family tumors (ESFTs). DAX1, an orphan member of the nuclear receptor superfamily, is up-regulated by EWS-FLI1 and plays a key role in the transformed phenotype of ESFTs. METHODS: To discover a functional inhibitor of DAX1 and EWS-FLI1, we screened small-molecular inhibitors using a DAX1 reporter assay system. RESULTS: K-234 and its derivatives, which were dihydroorotate dehydrogenase (DHODH) inhibitors, showed inhibitory effects in the reporter assay. K-234 inhibited the growth of Ewing's sarcoma with various fusion types, and K-234 derivatives altered the expression of EWS-FLI1-regulated genes. The DAX1 expression had no effect on the growth inhibitory effect of the K-234 derivatives, while DHODH overexpression or uridine treatment attenuated their inhibitory effects, suggesting that inhibition by K-234 derivatives occurs through DHODH inhibition. An in vivo study showed that a K-234 derivative clearly inhibited tumor growth in an Ewing's sarcoma xenograft mouse model. CONCLUSION: Taken together, the present results suggest that DHODH inhibitors can inhibit the function of DAX1/EWS-FLI1 in ESFTs and might be a therapeutic agent with potent anti-tumor activity for Ewing's sarcoma patients.
Assuntos
Sarcoma de Ewing , Humanos , Animais , Camundongos , Sarcoma de Ewing/tratamento farmacológico , Sarcoma de Ewing/genética , Sarcoma de Ewing/metabolismo , Di-Hidro-Orotato Desidrogenase , Proteína Proto-Oncogênica c-fli-1/genética , Proteína EWS de Ligação a RNA/genética , Proteínas de Fusão Oncogênica/genética , Proteínas de Fusão Oncogênica/metabolismo , Regulação Neoplásica da Expressão GênicaRESUMO
In Europe, with an incidence of 7.5 cases per million, Ewing sarcoma (ES) is the second most common primary malignant bone tumor in children, adolescents and young adults, after osteosarcoma. Since the 1980s, conventional treatment has been based on the use of neoadjuvant and adjuvant chemotherapeutic agents combined with surgical resection of the tumor when possible. These treatments have increased the patient survival rate to 70% for localized forms, which drops drastically to less than 30% when patients are resistant to chemotherapy or when pulmonary metastases are present at diagnosis. However, the lack of improvement in these survival rates over the last decades points to the urgent need for new therapies. Genetically, ES is characterized by a chromosomal translocation between a member of the FET family and a member of the ETS family. In 85% of cases, the chromosomal translocation found is (11; 22) (q24; q12), between the EWS RNA-binding protein and the FLI1 transcription factor, leading to the EWS-FLI1 fusion protein. This chimeric protein acts as an oncogenic factor playing a crucial role in the development of ES. This review provides a non-exhaustive overview of ES from a clinical and biological point of view, describing its main clinical, cellular and molecular aspects.
RESUMO
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.
RESUMO
The FET family proteins, which includes FUS, EWS, and TAF15, are RNA chaperones instrumental in processes such as mRNA maturation, transcriptional regulation, and the DNA damage response. These proteins have clinical significance: chromosomal rearrangements in FET proteins are implicated in Ewing family tumors and related sarcomas. Furthermore, point mutations in FUS and TAF15 are associated with neurodegenerative conditions like amyotrophic lateral sclerosis and frontotemporal lobar dementia. The fusion protein EWS::FLI1, the causative mutation of Ewing sarcoma, arises from a genomic translocation that fuses the low-complexity domain (LCD) of EWS (EWSLCD) with the DNA binding domain of the ETS transcription factor FLI1. This fusion not only alters transcriptional programs but also hinders native EWS functions like splicing. However, the precise function of the intrinsically disordered EWSLCD is still a topic of active investigation. Due to its flexible nature, EWSLCD can form transient interactions with itself and other biomolecules, leading to the formation of biomolecular condensates through phase separation - a mechanism thought to be central to the oncogenicity of EWS::FLI1. In our study, we used paramagnetic relaxation enhancement NMR, analytical ultracentrifugation, light microscopy, and all-atom molecular dynamics (MD) simulations to better understand the self-association and phase separation tendencies of EWSLCD. Our aim was to elucidate the molecular events that underpin EWSLCD-mediated biomolecular condensation. Our NMR data suggest tyrosine residues primarily drive the interactions vital for EWSLCD phase separation. Moreover, a higher density and proximity of tyrosine residues amplify the likelihood of condensate formation. Atomistic MD simulations and hydrodynamic experiments revealed that the tyrosine-rich N and C-termini tend to populate compact conformations, establishing unique contact networks, that are connected by a predominantly extended, tyrosine-depleted, linker region. MD simulations provide critical input on the relationship between contacts formed within a single molecule (intramolecular) and inside the condensed phase (intermolecular), and changes in protein conformations upon condensation. These results offer deeper insights into the condensate-forming abilities of the FET proteins and highlights unique structural and functional nuances between EWS and its counterparts, FUS and TAF15.