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Circulating IGF2BP3 enables risk stratification and predicts treatment response in Ewing sarcoma.

Ewing sarcoma (EWS), the second most common pediatric bone tumor, presents with a markedly heterogeneous clinical spectrum and optimal risk stratification is therefore crucial for improving treatment outcomes. The RNA-binding protein IGF2BP3 is a critical oncogenic driver of EWS malignancy. This study evaluates the clinical utility of circulating IGF2BP3 as a biomarker to predict treatment response and risk of disease progression in patients with EWS. Plasma samples from 60 patients with EWS diagnosed and treated at the IRCCS Rizzoli Orthopedic Institute (Bologna, Italy) were collected at diagnosis before treatment initiation and/or after induction chemotherapy. For 51 of these patients, blood was collected at diagnosis, prior to any treatments. For 25 patients, blood samples were available at diagnosis and before surgical intervention, allowing longitudinal analysis in the same patient. For 9 patients, blood was collected only after preoperative chemotherapy, before surgical intervention. Circulating IGF2BP3 levels were quantified using a highly specific and sensitive ELISA assay. Plasma samples from healthy donors served as controls. IGF2BP3 plasma levels were correlated with IGF2BP3 tumor tissue expression, established clinical risk factors, and cumulative incidence of relapse using univariable and multivariable analyses. Plasma IGF2BP3 levels were significantly elevated in patients with EWS compared with healthy controls, with a subset of patients (22/51, 43.2%) exhibiting clinically relevant concentrations. Circulating IGF2BP3 levels reflected tumor expression of the molecule and provided additional prognostic information beyond standard clinicopathologic features. The prognostic impact of circulating IGF2BP3 was primarily observed in patients with localized disease, in whom elevated levels were identified as a significant adverse prognostic factor for disease-specific survival (hazard ratio, 10.63; 95% CI, 1.27-88.62; P = 0.029). Longitudinal monitoring demonstrated that persistence of IGF2BP3 in plasma after induction chemotherapy was a strong predictor of poor clinical outcomes. Circulating IGF2BP3 represents a valuable biomarker for early risk stratification in EWS, particularly in patients with localized disease. Although this is single-marker assay, the expression of the molecule may impact on the fate of many mRNAs. We present an accurate, simple, cost-effective and easy clinical applicable tool to support risk-adapted therapeutic interventions. The limited number of employed patients warrants the need of larger cohorts for validation.

Humans

Disruption of Microhomology-mediated End-joining in Ewing Sarcoma.

Ewing sarcoma (EwS) is a group of bone and soft tissue cancers in children and young adults. Since EwS cells have pronounced sensitivity to radiation and chemotherapy-induced DNA damage, the role of the oncoprotein, EWS-FLI1, in DNA repair is likely. Here, we demonstrate that EWS-FLI1 causes a defect in microhomology-mediated end-joining (MMEJ) repair. EWSR1 is a splicing factor that promotes the faithful splicing of the POLQ pre-mRNA, required for the expression of POLΘ, a critical protein in the MMEJ pathway. Expression of EWS-FLI1, or loss of EWSR1, causes exon 25 skipping of the POLQ transcript, decreased POLΘ expression, impaired MMEJ, and cellular sensitivity to inhibitors of the Fanconi Anemia (FA), NHEJ, or HR pathways, through the mechanism of synthetic lethality. Knockdown of EWS-FLI1 expression restores POLΘ mitotic foci and increases MMEJ activity. Inhibitors of the FA, NHEJ, or HR therefore may provide a targeted therapy for patients with EwS.

Alternative end-joining

Integrated Immunotherapy Target Atlas for Ewing Sarcoma.

BACKGROUND/AIM: Ewing sarcoma is a fusion-driven malignancy with low tumor mutational burden, making recurrent tumor-associated antigens with favorable tumor-to-normal contrast central to immunotherapy development. We converted the Deng et al.-defined 32-gene Ewing Sarcoma Specific Signature (ESS32) into a practical target atlas by integrating tumor RNA expression with normal-tissue context, protein evidence, subcellular localization, and therapeutic accessibility. MATERIALS AND METHODS: A 38-gene set was analyzed, including ESS32 and six comparator antigens (STEAP1, LINGO1, PRAME, CD99, CD276/B7-H3, and ENPP1). Eight Gene Expression Omnibus datasets (n=854 samples) were assigned predefined roles spanning tumor-versus-skeletal-muscle comparison, broad normal-organ context, EWSR1::FLI1 perturbation, tumor-only support cohorts, cell-line models, and cross-sarcoma comparison. Results were overlaid with Human Protein Atlas and published proteomic/surfaceome evidence. RESULTS: In GSE17674, the strongest tumor-enriched transcripts included NKX2-2, NPY1R, STEAP1, RBM11, RNF182, LIPI, CD99, STEAP2, LOXHD1, and DCDC2. Normal-tissue and compartment data substantially reordered RNA-only ranking. NKX2-2 showed the strongest Ewing-associated signal but encodes a nuclear transcription factor, favoring peptide-HLA/T-cell receptor (TCR) or vaccine development. RBM11 and LIPI emerged as high-interest intracellular/secretome-associated candidates, with an explicit epididymal/male reproductive caveat for LIPI. CD99 and NPY1R illustrated normal-cell reservoir and receptor-distribution constraints. CONCLUSION: ESS32 should be interpreted as an EWSR1::FLI1-associated RNA discovery set, not as a pre-validated target panel. Practical nomination requires integration of RNA enrichment, normal-tissue distribution, protein evidence, cellular compartment, and modality compatibility before nomination of TCR, vaccine, antibody-drug conjugate (ADC), chimeric antigen receptor (CAR), radioligand, or validation-first candidates.

Humans

EWS-RNA Binding Protein 1: Structural Insights into Ewing Sarcoma by Conformational Dynamics Investigations.

BACKGROUND: Prior research has demonstrated that proteins play a significant role in the prognosis and treatments of various sarcomas, including Ewing sarcoma through the interplay of downstream signaling cascades. However, there is limited understanding about the strcucture conformation of EWSR1 and its structural implication in the prognosis of Ewsing Sarcoma by interaction with RNA molecules. AIMS: The primary goal of ongoing research is to determine how EWSR1 contributes to Ewing sarcoma. OBJECTIVE: The current study explores the complexity of EWSR1 structure and its conformational interactions with RNA in relation to Ewing sarcoma. METHODS: Here, we employed a comparative modeling approach to predict EWSR1 domains separately and assembled them into one structural unit using a DEMO server. Additionally, the RNA motifs interacting with EWSR1 were predicted, and the 3D model was built using RNAComposer. Protein-RNA docking and MD simulation studies were carried out to check the intermolecular interactions and stability behavior of docked EWSR1-RNA complexes. RESULTS: The overall results explore the structural insights into EWSR1 and their interactions with RNA, which may play a momentous role in co- and post-transcriptional regulation to control gene expression. CONCLUSION: Taken togather, our findings suggest that EWSR1 may be a useful therapeutic target for the diagnosis and management of Ewing sarcoma.

Sarcoma, Ewing

Extraskeletal Ewing sarcoma. An ultrastructural study.

Soft tissue tumors with the characteristics of Ewing sarcoma of bone have thus far only been studied by light microscopy. A pelvic tumor of this type in a 13-year-old girl was examined by electron microscopy. Comparison of its ultrastructural features with those of reported cases of bony Ewing sarcoma reveal much similarity. It is believed that they are probably identical and that the tumor cells are of immature mesenchymal type. However, their site of origin and the direction of their potential differentiation remain obscure.

Adolescent

p300/CBP is an essential driver of pathogenic enhancer activity and gene expression in Ewing sarcoma.

The t(11;22) translocation encodes the EWS::FLI1 fusion oncoprotein which is the primary driver of Ewing sarcoma. EWS::FLI1 creates unique, de novo pathogenic enhancers that drive gene expression and are a central mechanism of oncogenesis. Which chromatin regulatory proteins are critical to this mechanism is understudied. Here, we perform a comparative analysis of the function of the chromatin complexes MLL3/4 and p300/CBP in EWS::FLI1-mediated gene regulation. Using EWS::FLI1 degradation models, we define a subset of EWS::FLI1-sensitive enhancers whose activity correlates with p300/CBP function. We perturb both chromatin complexes to establish that in contrast to MLL3/4, p300/CBP is a critical regulator of EWS::FLI1-driven enhancer activity and downstream gene expression. We also show that p300/CBP small-molecule inhibition decelerates tumor growth in vivo. Our work highlights the context-dependent nature of chromatin protein activity at oncogenic enhancers and reveals p300/CBP as an important regulator of Ewing sarcoma.

Sarcoma, Ewing

Ewing sarcoma of the mandible: report of case.

A case of Ewing sarcoma, primarily localized in the mandible in a 19-year-old woman, is reported. The case report covers the initial symptoms, which are often misleading, the history, clinical, radiographic, and histologic features; and the treatment by surgery complemented with radiotherapy and chemotherapy.

Adult

Metastatic Ewing sarcoma to the heart simulating adriamycin cardiotoxicity.

A 20-year-old man with metastatic Ewing Sarcoma developed severe congestive heart failure. Because he had been treated with a large amount of Adriamycin, the diagnosis was initially thought to be Adriamycin cardiotoxicity. However, ante- and post-mortem studies revealed the presence of massive cardiac metastases. At post-mortem, there was no evidence of Adriamycin cardiotoxicity. This case emphasizes that cardiac metastases must be considered in the differential diagnosis of heart failure in patients treated with Adriamycin.

Adult

STAG2 loss in Ewing sarcoma alters enhancer-promoter contacts dependent and independent of EWS::FLI1.

Cohesin complexes carrying STAG1 or STAG2 organize the genome into chromatin loops. STAG2 loss-of-function mutations promote metastasis in Ewing sarcoma, a pediatric cancer driven by the fusion transcription factor EWS::FLI1. We integrated transcriptomic data from patients and cellular models to identify a STAG2-dependent gene signature associated with worse prognosis. Subsequent genomic profiling and high-resolution chromatin interaction data from Capture Hi-C indicated that cohesin-STAG2 facilitates communication between EWS::FLI1-bound long GGAA repeats, presumably acting as neoenhancers, and their target promoters. Changes in CTCF-dependent chromatin contacts involving signature genes, unrelated to EWS::FLI1 binding, were also identified. STAG1 is unable to compensate for STAG2 loss and chromatin-bound cohesin is severely decreased, while levels of the processivity factor NIPBL remain unchanged, likely affecting DNA looping dynamics. These results illuminate how STAG2 loss modifies the chromatin interactome of Ewing sarcoma cells and provide a list of potential biomarkers and therapeutic targets.

Sarcoma, Ewing

[Contribution to combined therapy of the Ewing-sarcoma (author's transl)].

The techniques and results from the treatment of 15 own cases with Ewing-sarcoma having undergone different therapeutic schemes are reviewed with the help of universal literature. These tumors are shown to need individual treatment which has to be adapted to the present data in each case.

Adolescent

Ewing sarcoma: phalangeal primary with fatal cardiac metastases.

A 39-year-old man had pain and swelling of the terminal phalanx of a finger. Radiograph was interpreted as osteomyelitis, and amputation through the mid-phalanx was performed. Histology revealed Ewing sarcoma. Lung metastases rapidly developed. Right lung irradiation and systemic chemotherapy, including doxorubicin, were instituted. He developed progressive severe right ventricular failure which was attributed to effects of large pulmonary metastases. Autopsy showed massive right ventricular metastases, the primary pathological cause of the heart failure, without evidence of doxorubicin cardiomyopathy.

Adult

Ewing sarcoma: treatment with high dose radiation and adjuvant chemotherapy.

Twenty-one patients with pathologically proven Ewing sarcoma without overt metastases at diagnosis were treated with a protocol designed by the Royal Marsden/St. Bartholomew's Hospitals Children's Solid Tumour Group (CSTG). They received megavoltage radiotherapy to the involved bone and adjuvant chemotherapy with a combination of four cytotoxic drugs. Seven patients have so far relapsed, four at the original site and three in other bones. The other 14 are clinically free of disease a median of 36 months from diagnosis. Comparison with a historical control group of 19 patients treated with surgery or radiotherapy, but without initial chemotherapy, shows a significant improvement in survival for the study group (P = 0.03). Seventeen of the controls have died. The treatment regime was moderately toxic, but there were no treatment-related deaths. These results confirm that an improved survival time and hopefully cure rate can be expected from treating Ewing tumour with high doses of megavoltage radiation and combination chemotherapy. Future goals must be the better control of large primary lesions and the eradication of micrometastases in other bones. The place of surgery should be re-evaluated in the treatment of the primary tumour, and better adjuvant chemotherapy regimes are needed.

Adolescent

[Improved prognosis of Ewing-sarcoma by combined irradiation and chemotherapy (author's transl)].

Until recently Ewing's sarcoma has been considered the most lethal malignant bone tumor with the poorest prognosis. An 8-year-old girl with Ewing's sarcoma is described who survived without recurrent disease for nearly 5 years now. 5-year-survival rates among large groups in the literature are reported, and different kinds of therapy compared. There are indications for a tendency that combined radio- and chemotherapy probably have the best results, since in most cases at the time of diagnosis the tumor already has metastasized or, like Lichtenstein believes, Ewing's sarcoma, primarily is of multicentric origin.

Bone Neoplasms

Targeting of the oncogenic fusion EWSR1-FLI1 in Ewing sarcoma by CRISPR/dCas9 silencers.

Despite the revolutionary impact of genome engineering tools in medicine, the safe and effective intracellular delivery of CRISPR remains a major obstacle to clinical applications. Here, we utilize precision molecular targeting and delivery strategies based on CRISPR-nuclease-dead Cas9 (dCas9) systems adapted for epigenetic repression (dCas9-Krüppel-associated box [KRAB]) to silence oncogenic drivers with high selectivity. As proof of principle, we target the EWSR1-FLI1 translocation, which encodes a chimeric and hard-to-drug oncogenic transcription factor driving approximately 85% of the cases of Ewing sarcoma (EWS)-an aggressive childhood malignancy. We describe the development of a programmable, non-viral polymeric system for the delivery of dCas9-KRAB as ribonucleoprotein (RNP) payloads for EWSR1-FLI1 repression. We demonstrate highly efficient intracellular delivery of RNPs loaded in polyamide-amine (PAMAM) polymers functionalized by guanidino groups, resulting in robust silencing of EWSR1-FLI1 both in established cell line xenografts and in EWS-related patient-derived xenografts (PDXs) of EWS. We show that silencing of EWSR1-FLI1 is accompanied by potent anti-tumor effects. Collectively, we characterize an effective non-viral platform for in vivo delivery of dCas9-KRAB/RNPs, which could be adapted for the repression of any oncogene. We further outline dCas9/RNP formulations for future therapeutic applications to treat poor-prognosis cancers driven by hard-to-drug oncogenes.

CRISPR-dCas9