# Characterizing ETV6 as a regulator of EWS-FLI oncoprotein in Ewing Sarcoma

> **NIH NIH F30** · HARVARD MEDICAL SCHOOL · 2021 · $51,036

## Abstract

PROJECT SUMMARY/ABSTRACT
Ewing sarcoma (ES) is the second most common pediatric tumor involving bone. Survival rates for patients with
metastatic disease remain dismal at 20-30%, presenting an unmet clinical need. Pediatric cancers, on average,
exhibit lower mutational burdens compared to adult cancers, concealing disease biology and potential targets
for treatment, posing a major barrier to novel drug discovery. Indeed, ES tumors exhibit extremely few oncogenic
mutations, with the exception of the characteristic 11;22 chromosomal translocation, which creates the
oncogenic EWS-FLI fusion transcription factor in 85-90% of cases. The EWS-FLI oncoprotein closes and opens
chromatin at specific motifs in the genome, inducing profound epigenetic dysregulation. To investigate ES
biology, a genome-scale CRISPR-Cas9 screen was performed, which identified the transcription factor, ETV6,
as a gene essential for ES cell survival. ETV6 is a repressive transcription factor that has previously been shown
to mediate gene repression through the direct recruitment of the histone deacetylating (HDAC) enzyme, HDAC3.
Preliminary experiments have demonstrated that ETV6 shares thousands of genomic binding sites with EWS-
FLI in ES cells, including binding at EWS-FLI-up-regulated genes. Furthermore, ETV6 over-expression reduces
abundance of the promotive histone mark, H3K27ac, consistent with its previously described repressive function.
Thus, this proposal will address the hypothesis that ETV6 is essential for ES cell survival by repressing a subset
of EWS-FLI-induced target genes via the recruitment of HDAC3. Aim 1 will assess the essentiality of this gene
in models of ES in vitro and in vivo and elucidate the molecular mechanism of decreased survival of ES cells
when ETV6 is suppressed. Aim 2 will define the transcriptional programs of ETV6 and EWS-FLI to determine
whether ETV6 represses a subset of EWS-FLI target genes that are deleterious for cell survival and growth.
Finally, Aim 3 will investigate whether ETV6 represses EWS-FLI target genes by recruiting HDAC3 and whether
ES cells are sensitive to the selective HDAC3 inhibitor, RGFP966. Altogether, this work will characterize a novel
essential gene in ES and highlight a potential novel therapeutic approach for ES.

## Key facts

- **NIH application ID:** 10088329
- **Project number:** 5F30CA246925-02
- **Recipient organization:** HARVARD MEDICAL SCHOOL
- **Principal Investigator:** Diana Ye Lu
- **Activity code:** F30 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $51,036
- **Award type:** 5
- **Project period:** 2020-06-01 → 2022-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10088329

## Citation

> US National Institutes of Health, RePORTER application 10088329, Characterizing ETV6 as a regulator of EWS-FLI oncoprotein in Ewing Sarcoma (5F30CA246925-02). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10088329. Licensed CC0.

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