Abstract 5109: Somatic CRISPR/Cas9-mediated gene editing enables versatile brain tumor modeling

Abstract

Abstract Despite substantial advances in the molecular classification of pediatric brain tumors over the last decade, many tumors are still incurable, have a poor prognosis or therapy-related detrimental long term effects. To develop innovative and modern therapy approaches, sophisticated mouse models, faithfully reflecting the human disease are urgently needed. However, the development of transgenic mouse lines is a time consuming process that is confronted with an increasing number of candidate genes resulting from next generation sequencing of tumor specimens. To cope with this discrepancy, more adaptable animal models are needed. Using somatic gene transfer to manipulate cells in situ holds great advantages in terms of speed and flexibility. We therefore established a system in which we are using the CRISPR/Cas9 system for somatic disruption of candidate tumor suppressor genes (TSGs) in combination with transposon-mediated overexpression of candidate oncogenes to induce murine brain tumors. By deleting Ptch1 in murine cerebella, we induced Sonic Hedgehog (SHH) subgroup medulloblastoma with high penetrance and short latency. We characterized the induced mutations in depth and did not detect recurrent off-targets using unsupervised whole genome sequencing. We further demonstrated that this method is suited to induce other brain tumor entities by targeting multiple TSGs at the same time or by combining TSG targeting with overexpression of certain oncogenes. To date we established five novel mouse models using this system. Two of these resulted from simultaneous deletion of Nf1, Pten and Trp53 or from combining overexpression of a MET fusion with a loss of Trp53, respectively. Both of these combinations led to efficient glioblastoma induction in the murine forebrain. Our results demonstrate a fast and flexible system for validating novel candidate genes and for generating faithful animal models of human cancer. Citation Format: Marc Zuckermann, Britta Ismer, Volker Hovestadt, Christiane B. Knobbe-Thomsen, Marc Zapatka, Paul A. Northcott, Martine F. Roussel, Guido Reifenberger, Peter Lichter, Stefan M. Pfister, Daisuke Kawauchi, Jan Gronych, David T. Jones. Somatic CRISPR/Cas9-mediated gene editing enables versatile brain tumor modeling [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 5109.