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Updated: Aug 19, 2026
Mapping the Structure-Function Relationships of Disordered Oncogenic Transcription Factors Using Transcriptomic Analysis
Published on: June 27, 2020
EWS-FLI1 target genes recovered from Ewing's sarcoma chromatin
Christine Siligan1, Jozef Ban, Radostina Bachmaier
1Children's Cancer Research Institute (CCRI), St Anna Kinderspital, Kinderspitalgasse 6, Vienna A1090, Austria.
Abstract:
In all, 85% of Ewing's sarcoma family tumors (ESFT), a neoplasm of unknown histogenesis, express EWS-FLI1 transcription factor gene fusions. To characterize direct target genes avoiding artificial model systems, we cloned genomic DNA from ESFT chromatin precipitating with EWS-FLI1. We now present a comprehensive list of 99 putative transcription factor targets identified, for the first time, by a hypothesis-free approach based on physical interaction. Gene-derived chromatin fragments co-precipitating with EWS-FLI1 were nonrandomly distributed over the human genome and localized predominantly to the upstream region and the first two introns of the genes. At least 20% of putative direct EWS-FLI1 targets were neural genes. One-third of genes recovered showed a significant ESFT-specific expression pattern and were found to be altered upon RNAi-mediated knockdown of EWS-FLI1. Among them, MK-STYX, encoding a MAP kinase phosphatase-like protein, was consistently expressed in ESFT. EWS-FLI1 was found to drive MK-STYX expression by binding to a single ETS binding motif within the first gene intron. MK-STYX serves as precedence for successful recovery of direct EWS-FLI1 targets from the authentic ESFT cellular context, the most relevant system to study oncogenic mechanisms for the discovery of new therapeutic targets in this disease.
Insights
Researchers identified 99 direct target genes of the EWS-FLI1 fusion protein in Ewing
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Ewing's sarcoma family of tumors (ESFT) are aggressive neoplasms characterized by the expression of EWS-FLI1 fusion proteins in 85% of cases.
- Understanding the direct transcriptional targets of EWS-FLI1 is crucial for elucidating ESFT pathogenesis and identifying therapeutic strategies.
- Previous studies often relied on artificial model systems, limiting the characterization of EWS-FLI1 targets in the authentic tumor context.
Purpose of the Study:
- To identify direct transcriptional targets of EWS-FLI1 using a hypothesis-free, physical interaction-based approach in ESFT.
- To characterize the genomic localization and functional relevance of these direct targets within the ESFT cellular environment.
- To identify novel therapeutic targets by understanding EWS-FLI1-driven gene expression.
Main Methods:
- Chromatin immunoprecipitation followed by cloning of co-precipitated genomic DNA fragments associated with EWS-FLI1 in ESFT.
- Bioinformatic analysis to identify putative transcription factor binding sites and gene localization.
- RNA interference (RNAi)-mediated knockdown of EWS-FLI1 to assess gene expression changes.
- Analysis of gene expression patterns and functional annotation of identified targets.
Main Results:
- A comprehensive list of 99 putative direct EWS-FLI1 target genes was identified through a hypothesis-free method.
- These targets were predominantly located in upstream regions and introns of genes, with approximately 20% being neural genes.
- One-third of the identified genes exhibited ESFT-specific expression and were regulated by EWS-FLI1, as confirmed by RNAi knockdown.
- The MAP kinase phosphatase-like gene MK-STYX was identified as a direct EWS-FLI1 target, driven by EWS-FLI1 binding to an intronic ETS motif.
Conclusions:
- This study presents the first comprehensive list of direct EWS-FLI1 targets identified from authentic ESFT, bypassing artificial models.
- The findings highlight the significant role of EWS-FLI1 in driving oncogenic gene expression programs, including neural-related genes.
- MK-STYX represents a validated direct target and serves as a precedent for discovering new therapeutic targets in Ewing's sarcoma.
