EWS/FLI1 Characterization, Activation, Repression, Target Genes and Therapeutic Opportunities in Ewing Sarcoma

Sep 24, 2026

Uploaded by Jasmine

Despite their clonal origins, Ewing sarcomas evolve into heterogeneous tumor communities with phenotypically distinct subpopulations shaped by intrinsic programming and dynamic microenvironments. Childhood malignancies often show limited mutational burden yet maintain high cellular heterogeneity largely driven by epigenetic mechanisms. Relapse and metastatic disease remain poorly controlled, and disease biology centers on the EWS/FLI1 fusion, whose distinct fusion protein activities generate transcriptional and cellular variability across tumors. This review characterizes EWS/FLI1 activation and repression mechanisms, links them to tumor heterogeneity, and highlights therapeutic opportunities targeting the aberrant fusion.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages22

Reading Time55 min

AccessFree to download

Abstract

Keywords

Introduction

Characterization of EWS/FLI1

Review EWS/FLI1 Characterization, Activation, Repression, Target Genes and Therapeutic Opportunities in Ewing Sarcoma Muhammad Yasir, Jinyoung Park and Wanjoo Chun * Citation: Yasir, M.; Park, J.; Chun, W. EWS/FLI1 Characterization, Activation, Repression, Target Genes and Therapeutic Opportunities in Ewing Sarcoma. Int. J. Mol. Sci. 2023, 24, 15173. [https://doi.org/10.3390/](https://doi.org/10.3390/)[ ](https://doi.org/10.3390/)ijms242015173 Academic Editor: Valentina De Falco Received: 19 September 2023 Revised: 11 October 2023 Accepted: 12 October 2023 Published: 14 October 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ([https://](https://)[ ](https://)[creativecommons.org/licenses/by/](creativecommons.org/licenses/by/)[ ](creativecommons.org/licenses/by/)[4.0/](4.0/)) . Department of Pharmacology, Kangwon National University School of Medicine, Chuncheon 24341, Republic of Korea; [yasir.khokhar1999@gmail.com](yasir.khokhar1999@gmail.com) (M.Y.); [jinyoung0326@kangwon.ac.kr](jinyoung0326@kangwon.ac.kr) (J.P.) * [Correspondence: wchun@kangwon.ac.kr](Correspondence: wchun@kangwon.ac.kr); Tel.: +82-33-250-8853 Abstract: 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. Keywords: EWS/FLI1; therapeutic opportunities; Ewing sarcoma target genes 1. Introduction Ewing sarcoma is an infrequent tumor that predominantly develops in the bones of children and adolescents [1] . Although there have been notable advancements in treatment over recent decades, survival rates have remained disappointingly low, even among patients with localized Ewing sarcoma. This is due to a signiﬁcant portion of these tumors showing resistance to standard therapies, leading to frequent relapses. Furthermore, approximately a quarter of cases are diagnosed with disseminated disease, which carries an exceedingly grim prognosis [2] . Hence, there is a pressing demand for novel targeted therapies that can provide improved efﬁcacy and minimize adverse effects compared to the conventional chemotherapy and radiotherapy currently in use. In this regard, gaining insights into the molecular mechanisms underlying Ewing sarcoma pathogenesis offers valuable knowledge that could aid in the development of innovative targeted biological treatments. Ewing sarcomas are distinguished by chrom

FAQs

What drives heterogeneity in Ewing sarcoma cells despite a common driver fusion?

Ewing sarcoma cells share the EWS/FLI1 driver but exhibit significant differences in transcriptional activity. Distinct fusion protein activities and epigenetic mediation contribute to heterogeneous cellular phenotypes within and among tumors.

Why do relapsed or metastatic Ewing sarcoma patients face poor outcomes?

The review notes that a substantial portion of tumors show resistance to standard therapies, leading to frequent relapses. About a quarter of cases present with disseminated disease, associated with a grim prognosis.

What is the focus of the review regarding EWS/FLI1?

The review characterizes the role of the EWS/FLI fusion protein by describing its general mechanism of activation. It also considers implications for tumor heterogeneity and discusses therapeutic opportunities to target the aberrant fusion.

Sep 24, 2026

Uploaded by Jasmine