Class I histone deacetylases (HDAC) critically contribute to Ewing sarcoma pathogenesis.

Area of Science:

• Oncology
• Molecular Biology
• Cancer Genetics

Background:

• Histone acetylation and deacetylation are implicated in Ewing sarcoma (EwS) pathogenesis.
• Class I histone deacetylases (HDACs) were investigated for their role in EwS.

Purpose of the Study:

• To investigate the role of class I HDACs in EwS pathogenesis.
• To evaluate the therapeutic potential of class I HDAC inhibitors in EwS.

Main Methods:

• Utilized various class I HDAC inhibitors (TSA, Romidepsin, Entinostat, PCI-34051).
• Employed CRISPR/Cas9 knockouts and RNA interference for class I HDACs.
• Analyzed effects using microarray, qRT-PCR, western blotting, Co-IP, proliferation, apoptosis, differentiation, invasion assays, and xenograft models.

Main Results:

• Class I HDACs are constitutively expressed in EwS, with high expression correlating with decreased survival.
• Knockout of HDAC1 and HDAC2 inhibited invasiveness and tumor growth in vivo.
• HDAC inhibitors blocked EWS-FLI1 specific gene expression and suppressed metastasis-associated genes.
• HDAC inhibitors enhanced sensitivity to chemotherapy and promoted endothelial/neuronal differentiation.
• HDAC inhibitors synergized with EED inhibitors, inhibiting tumor growth in xenografts and forming complexes with PRC2.

Conclusions:

• Class I HDACs are key mediators of the EWS-ETS transcriptional program in EwS.
• Combination therapy involving HDAC inhibitors offers a novel treatment strategy for EwS.