The O-glycosyltransferase C1GALT1 promotes EWSR1::FLI1 expression and is a therapeutic target for Ewing sarcoma

  • Nat Commun. 2025 Feb 2;16(1):1267. doi: 10.1038/s41467-025-56632-0.
Shahid Banday  1 ,  Alok K Mishra  2 ,  Romana Rashid  3 ,  Tianyi Ye  2 ,  Amjad Ali  2 ,  Junhui Li  2 ,  Jason T Yustein  4 ,  Michelle A Kelliher  2 ,  Lihua Julie Zhu  2  5 ,  Sara K Deibler  2 ,  Sunil K Malonia  6 ,  Michael R Green  2
Affiliations
  • 1. Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA. [email protected].
  • 2. Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA.
  • 3. Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA.
  • 4. Winship Cancer Institute and Aflac Cancer and Blood Disorders Center, Emory University, Atlanta, GA, 30322, USA.
  • 5. Program in Molecular Medicine and Department of Genomics and Computational Biology, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA.
  • 6. Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA. [email protected].
PMID: 39894896 DOI: 10.1038/s41467-025-56632-0
Abstract

Ewing sarcoma (ES) is an aggressive bone Cancer driven by the oncogenic fusion-protein EWSR1::FLI1, which is not present in normal cells and is therefore an attractive therapeutic target. However, as a transcription factor, EWSR1::FLI1 is considered undruggable. Factors that promote EWSR1::FLI1 expression, and thus whose inhibition would reduce EWSR1::FLI1 protein levels and function, are potential drug targets. Here, using genome-scale CRISPR/Cas9 knockout screening, we identify C1GALT1, a galactosyltransferase required for the biosynthesis of many O-glycoproteins, as a factor that promotes EWSR1::FLI1 expression. We show that C1GALT1 acts by O-glycosylating the pivotal Hedgehog (Hh) signaling component Smoothened (Smo), thereby stabilizing Smo and stimulating the Hh pathway, which we find directly activates EWSR1::FLI1 transcription. Itraconazole, an FDA-approved anti-fungal agent that is known to inhibit C1GALT1, reduces EWSR1::FLI1 levels in ES cell lines and suppresses growth of ES xenografts in mice. Our study reveals a therapeutically targetable mechanism that promotes EWSR1::FLI1 expression and ES tumor growth.

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