Here we report that pharmacological inhibition of Enhancer of Zeste Homolog 2 (EZH2) at doses reducing H3K27 trimethylation, but not cell viability, selectively and reversibly induces G<sub>D2</sub> surface expression in Ewing sarcoma cells.
The polycomb proteins BMI-1 and EZH2 are highly overexpressed by Ewing sarcoma (ES), a tumor of stem cell origin that is driven by EWS-ETS fusion oncogenes, most commonly EWS-FLI1.
Inhibition of β-catenin, poly (ADP-ribose) polymerase 1 (PARP1), or enhancer of zeste homolog 2 (EZH2) suppressed cell growth in a murine model of Ewing's sarcoma, suggesting the utility of the current system as a preclinical model.
These results clearly identify the ET-derived antigens, EZH2(666) and CHM1(319), as suitable targets for protective allo-restricted human CD8(+) T-cell responses against non-immunogenic ET and may benefit new therapeutic strategies in ET patients treated with allogeneic stem cell transplantation.
Downregulation of EZH2 by RNA interference suppressed tumor development and metastasis in vivo and microarray analysis of EZH2 knock down revealed an EZH2-maintained, undifferentiated, reversible phenotype in ET.
Among relevant candidate transcripts induced by EWS-FLI-1 in hMSCs, we found the polycomb group gene EZH2, which we show to play a critical role in Ewing's sarcoma growth.