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Published on: June 27, 2020
Functional Genomic Screening Reveals Splicing of the EWS-FLI1 Fusion Transcript as a Vulnerability in Ewing Sarcoma
Patrick J Grohar1, Suntae Kim2, Guillermo O Rangel Rivera3
1Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
Ewing sarcoma cells rely on the EWS-FLI1 fusion. Researchers found that targeting RNA processing proteins like HNRNPH1 and SF3B1 disrupts EWS-FLI1, offering a new therapeutic vulnerability for Ewing sarcoma.
Area of Science:
- Oncology
- Molecular Biology
- RNA Biology
Background:
- Ewing sarcoma is a pediatric bone cancer driven by the EWS-FLI1 fusion oncogene.
- The EWS-FLI1 fusion protein is essential for the survival and proliferation of Ewing sarcoma cells.
- Understanding the regulatory mechanisms of EWS-FLI1 expression is crucial for developing targeted therapies.
Purpose of the Study:
- To identify proteins involved in the processing of the EWS-FLI1 pre-mRNA.
- To investigate the role of specific RNA-binding proteins and splicing factors in EWS-FLI1 expression.
- To explore the therapeutic potential of targeting EWS-FLI1 RNA processing in Ewing sarcoma.
Main Methods:
- Development of an assay to measure EWS-FLI1 activity.
- Genome-wide RNA interference (RNAi) screening to identify essential genes.
- Analysis of specific RNA-binding proteins (HNRNPH1) and splicing factors (SF3B1) in Ewing sarcoma cell lines.
- Assessment of the impact of gene knockdown on EWS-FLI1 transcript and protein levels.
Main Results:
- Proteins essential for EWS-FLI1 pre-mRNA processing were identified.
- Ewing sarcoma cells with a specific EWSR1 genomic breakpoint require HNRNPH1 for in-frame EWS-FLI1 expression.
- Loss of function of SF3B1, a U2 snRNP component, significantly impacts EWS-FLI1 fusion transcript levels.
- Disruption of EWS-FLI1 splicing alters oncogenic protein expression and downstream gene activity.
Conclusions:
- The processing of the EWS-FLI1 fusion RNA represents a critical vulnerability in Ewing sarcoma.
- Targeting RNA processing machinery, including HNRNPH1 and SF3B1, could be a viable therapeutic strategy.
- Further research into splicing factor dependencies may lead to novel treatments for Ewing sarcoma.
