IGF2 supports glioblastoma growth and immune evasion through a combination of tumor cell-intrinsic and -extrinsic mechanisms.

ABSTRACT: BackgroundGIntratumoral and intertumoral heterogeneity combined with immunosuppressive tumor microenvironments (TME) contribute to the poor outcomes associated with glioblastoma (GBM). Well-characterized immunocompetent models that recapitulate human GBM features are urgently needed to identify targets in the TME and develop novel therapeutics. Here, we used multiomic approaches to characterize syngeneic mouse brain tumor stem cell lines in vitro and in orthotopically engrafted tumors. METHODS: Whole-genome sequencing, transcriptomics, ATAC-sequencing, and imaging mass cytometry were used to characterize syngeneic brain tumor stem cell lines derived from Trp53(+/-)/Nf1(+/-) C57Bl6 mice. Mouse and human bulk, single-cell, and spatial sequencing datasets were analyzed for validation. CRISPR/Cas9 and shRNA were used for gene knockdowns. Tumor growth was investigated using orthotopic engraftment in syngeneic C57Bl6 mice. RESULTS: One of the syngeneic lines, mBT0309, generated tumors with histopathological characteristics of GBM. mBT0309 displayed amplification and high expression of Igf2. Copy number gains at the IGF2 locus were observed in human GBM tumors and stem cell lines. Furthermore, we determined that high IGF2 RNA expression is associated with poor survival in GBM patients. Imaging mass cytometry on mBT0309 tumors showed early infiltration of monocyte-derived macrophages, vascularization, and cell states characteristic of human GBM. Genetic targeting of Igf2 decreased in vitro cell growth, improved survival of engrafted mice, and decreased the percentage of Arginase-1+ macrophages in mBT0309 tumors. CONCLUSIONS: mBT0309 is a valuable syngeneic model for studying immunosuppression and therapeutic resistance in GBM. IGF2 offers promise as a valuable therapeutic target to combat tumor growth and immunosuppression in GBM patients.