Abstract 3525: VGLL2-NCOA2 leverages developmental programs for pediatric sarcomagenesis

Abstract

Abstract Clinical sequencing efforts are rapidly identifying sarcoma gene fusions that have not been functionally validated for their transformation capacity and biological activity. An example is the new fusion of transcriptional coactivators, VGLL2-NCOA2, found in infantile rhabdomyosarcoma. To delineate VGLL2-NCOA2 tumorigenic mechanisms and identify therapeutic vulnerabilities, we implemented a cross-species comparative oncology approach with zebrafish, mouse allograft, and patient samples. We found that in our transgenic zebrafish and mouse allograft models, VGLL2-NCOA2 is sufficient to generate mesenchymal tumors that display features of immature skeletal muscle. Zebrafish and mouse VGLL2-NCOA2 tumors are consistent with the human disease histologically and transcriptionally, and express diagnostic rhabdomyosarcoma markers. We found a shared molecular feature of these tumors was a suppression of myogenic differentiation pathways and reactivation of developmental programs. To identify impacted developmental programs, we transcriptionally clustered zebrafish VGLL2-NCOA2 tumors with the trajectory of early zebrafish development. A subset of VGLL2-NCOA2 zebrafish tumors cluster with embryonic somitogenesis and pinpoint VGLL2-NCOA2 developmental targets, including a RAS family GTPase, ARF6. In VGLL2-NCOA2 zebrafish, mouse allograft, and patient tumors, ARF6 is highly expressed and is absent from mature skeletal muscle. ARF6 knockout in our C2C12-VGLL2-NCOA2 cell culture model suppresses VGLL2-NCOA2 soft agar colony formation capacity, suggesting a genetic cooperating event in the disease. Our data indicate that VGLL2-NCOA2 is an oncogene which leverages developmental programs for tumorigenesis, and that the reactivation or persistence of ARF6 could represent a therapeutic opportunity. Citation Format: Sarah Watson, Collette A. LaVigne, Lin Xu, Didier Surdez, Joanna Cyrta, Delia Calderon, Matthew V. Cannon, Matthew R. Kent, Katherine M. Silvius, Jack P. Kucinski, Emma N. Harrison, Whitney Murchison, Dinesh Rakheja, Franck Tirode, Olivier Delattre, James F. Amatruda, Genevieve C. Kendall. VGLL2-NCOA2 leverages developmental programs for pediatric sarcomagenesis. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3525.