Genome-Wide CRISPR-Cas9 Screens Expose Genetic Vulnerabilities and Mechanisms of Temozolomide Sensitivity in Glioblastoma Stem Cells

Summary: Glioblastoma therapies have remained elusive due to limitations in understanding mechanisms of growth and survival of the tumorigenic population. Using CRISPR-Cas9 approaches in patient-derived GBM stem cells (GSCs) to interrogate function of the coding genome, we identify actionable pathways responsible for growth, which reveal the gene-essential circuitry of GBM stemness and proliferation. In particular, we characterize members of the SOX transcription factor family, SOCS3, USP8, and DOT1L, and protein ufmylation as important for GSC growth. Additionally, we reveal mechanisms of temozolomide resistance that could lead to combination strategies. By reaching beyond static genome analysis of bulk tumors, with a genome-wide functional approach, we reveal genetic dependencies within a broad range of biological processes to provide increased understanding of GBM growth and treatment resistance. : MacLeod et al. describe genome-wide CRISPR-Cas9 screens identifying genetic vulnerabilities across a panel of patient-derived glioblastoma stem cell cultures. Regulators of stemness (SOX2, SOX9, DOT1L, and SOCS3) and stress response (ufmylation and ERAD pathways) govern the growth of glioblastoma stem cells. Chemogenomic screens using temozolomide identify modulators of sensitivity to chemotherapy. Keywords: glioblastoma, glioblastoma stem cells, CRISPR-Cas9, fitness genes, functional genomic