Genetic Screen in a Pre-Clinical Model of Sarcoma Development Defines Drivers and Therapeutic Vulnerabilities

High-grade complex karyotype sarcomas are a heterogeneous group of more than seventy tumors that vary in histology, clinical course, and patient demographics. Despite these differences, these high-grade sarcomas are treated similarly with varying outcomes. Pre-clinical models of distinct human sarcoma subtypes would advance insights into the relationships between sarcomas and inform therapeutic decisions. We describe the transformation of human mesenchymal stem cells into multiple subtypes of high-grade sarcoma. Using a pooled genetic screening approach, we identified key drivers and potential modifiers of transformation. YAP1, KRAS, CDK4, and PIK3CA were validated as drivers of four distinct sarcoma subtypes, undifferentiated pleomorphic sarcoma (UPS), myxofibrosarcoma (MFS), leiomyosarcoma (LMS), and osteosarcoma (OS). Histologically and phenotypically these tumors reflect human sarcomas including the pathognomonic complex karyotype and YAP1 amplification. Transcriptome analysis confirmed that these tumors accurately recapitulate human disease. This model is a tool that can be used to begin to understand pathways and mechanisms driving human sarcoma development, the relationship between sarcoma subtypes and to identify and test new therapeutic targets for this aggressive and heterogeneous disease.