Generation of an iPSC-derived alveolar rhabdomyosarcoma cell line during directed endothelial differentiation.

Alveolar rhabdomyosarcoma (ARMS) is an aggressive soft tissue sarcoma typically driven by the oncofusion protein PAX3::FOXO1 (P3F). Despite ARMS tumor histology and transcriptome resembling skeletal muscle, these tumors arise in areas devoid of skeletal muscle, indicating that non-myogenic cells can give rise to ARMS. Our lab demonstrated that endothelial progenitors are a cell of origin for rhabdomyosarcoma. Here we provide a protocol for generating iPSC-derived alveolar rhabdomyosarcoma cells (iARMS) during endothelial directed differentiation through enforced expression of P3F. This model allows for dissection of how P3F mediates transformation of endothelial progenitors into aggressive myogenic tumors.