Abstract 5443: Identifying key regulators of glioblastoma cancer stem cells

Abstract Glioblastoma multiforme (GBM) has a dire prognosis that has had little progress over the past three decades. The existence of a unique population of stem-like gene signature baring quiescent cells (GSCs) within GBM are important for GBM tumorigenesis, therapy-resistance and recurrence. Our lab has developed one of the most faithful genetically engineered mouse models, encompassing a Nestin promoter-enhancer driven CreERT2-H2BeGFP-hDTR cassette (hereafter as CGD), that allows us to accurately capture and isolate GSCs in mouse GBM. The next logical step is to leverage these tools to uncover therapeutic vulnerabilities of GSCs and make a meaningful impact on GBM patient outcomes. To our knowledge, very few studies have explored the functional regulators of GSCs using a CRISPR/Cas9 screening approach. Our GSC signature provides a strong foundation for performing targeted in vitro or in vivo screens. In this study, to identify functionally important genes that may regulate GSC self-renewal and tumorigenic properties, an in vitro CRISPR knockout screens using a gene library derived from the GSC signature. The viral library was applied to low passage primary cultures of FACS sorted CGDGFP+ and CGDGFP- GBM cells developed from CGD; Nf1f/+;Trp53f/f;Ptenf/+ mice, respectively. The result of our in vitro CRISPR knock-out screen demonstrated guide depletion of Atp1b2-sgRNA in CGDGFP+ but not in CGDGFP- cells. The main objective of this study is to utilize in vitro and in vivo functional assays to test the difference between Atp1b2 WT and Atp1b2 KO GSCs and Atp1b2 WT vs KO GSC-derived tumors. Having a targeted candidate gene list is also particularly helpful for designing an in vivo CRISPR knockout screen, which is more physiological relevant. Therefore, I propose to use the candidate gene list derived from the in vitro screen as a starting point. The in vivo screen can provide valuable insights for the selection of the most optimal candidates for anti-GSC therapies. Citation Format: Tao Wang, Xuanhua Xie, Luis F. Parada. Identifying key regulators of glioblastoma cancer stem cells abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 5443.