Abstract LB-197: Transposon mutagenesis and CRISPR/Cas9 screening reveal pathways driving peripheral nerve sheath tumor development and maintenance

Malignant Peripheral Nerve Sheath tumors(MPNSTs) are highly aggressive soft tissue sarcomas derived Schwann cell tumors. Half of these tumors occur sporadically, while the rest occur in the context of Neurofibromatosis Type 1 Syndrome (NF1) developing from pre-existing plexiform neurofibromas. NF1 is characterized by loss-of-function mutations in the gene encoding neurofibromin, a negative regulator of the oncogenic Ras pathway. To better understand genetic factors that give rise to MPNSTs, we performed a Sleeping Beauty (SB) transposon screen in mice. The results implicated Wnt/β-catenin, PI3K-AKT-mTOR, growth factor receptor signaling, and other pathways. It is our goal to understand the role of these pathways in human Schwann cell transformation, tumorigenesis, and tumor maintenance. We next sought to validate SB screen gene hits in a human cellular model using CRISPR/Cas9 technology as a tool to induce loss-of-function mutations in tumor suppressor gene (TSG) and oncogene candidates. A total 103 genes were independently targeted with multiple guideRNAs in immortalized human Schwann and MPNST cell lines and effects on transformation assessed. Transformation was assessed by anchorage-independent colony formation in soft agar, transwell migration, and tumor formation in NRG mice. In these assays, more than 30 genes scored as TSG candidates. Our results revealed a role for the Wnt/β-catenin, Hippo/Yap, PI3K-AKT-mTOR, Rho, and growth factor receptor signaling pathways in human neurofibroma and MPNST development and maintenance. These are generating hypothesis driven pre-clinical treatment studies we9re pursuing now. Citation Format: German L. Velez Reyes, Nicholas Koes, Gabriel Kaufmann, Esther Ryu, David A. Largaespada. Transposon mutagenesis and CRISPR/Cas9 screening reveal pathways driving peripheral nerve sheath tumor development and maintenance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-197.