A syngeneic spontaneous zebrafish model oftp53-deficient, EGFRviii, and PI3KCAH1047R-driven glioblastoma reveals inhibitory roles for inflammation during tumor initiation and relapsein vivo

Abstract

AbstractTo build a patient-relevantin vivomodel of human glioblastoma, we expressed common oncogenic variants including activated human EGFRviiiand PI3KCAH1047Runder the control of the radial glial-specific promoterher4.1in syngeneictp53loss-of-function mutant zebrafish. Robust tumor formation was observed prior to 45 days of life, with a gene expression signature similar to human glioblastoma of the mesenchymal subtype, along with a strong inflammatory component. Within early stage tumor lesions, and in an intact and endogenous tumor microenvironment, we visualized infiltration of phagocytic cells, as well as internalization of tumor cells bympeg1.1:GFP+ microglia/macrophages, suggesting negative regulatory pressure by pro-inflammatory cell types on tumor growth at early stages of glioblastoma initiationin vivo. Furthermore, CRISPR/Cas9-mediated gene targeting of master inflammatory transcription factorsirf7andirf8led to increased tumor formation in the primary context, while suppression of microglial/macrophage activity led to enhanced tumor cell engraftment following transplantation into otherwise immune competent zebrafish hosts. Altogether, we developed a genetically-relevant model of aggressive human glioblastoma and harnessed the unique advantages of zebrafish including live imaging, high-throughput genetic and chemical manipulations to highlight important tumor suppressive roles for the innate immune system on glioblastoma initiation, with important future significance for therapeutic discovery and optimizations.