STEM-11. A GLIOBLASTOMA SINGLE-CELL META-ATLAS IDENTIFIES NOVEL NEUROVASCULAR PROGENITOR IN TUMORS

Abstract

Abstract Glioblastomas (GBM) are defined by cell type heterogeneity that underlies treatment resistance and brain invasion. Recent studies have identified reactivation of neurodevelopmental cells and gene expression programs in GBM. Here, we leverage a neurodevelopmental perspective to identify novel gene signatures in GBM. To do so, we assembled a glioblastoma meta-atlas comprised of 73,376 single-cell transcriptomes from 7 published studies. With these data, we developed a novel module generation strategy to mitigate batch effects, enabled analysis of signatures in each tumors, and emphasized modules observed across multiple tumors. Using this approach, we validated known tumor cell types and axes of variation, and also identified novel stemness programs that were uniquely expressed across distinct progenitor populations. Within progenitor subtypes, we identified a neurovascular progenitor (NVP) of cells expressing a mixed vascular signature including genes characteristic of mural and endothelial identity as well as transcriptional programs reminiscent of neural stem cells. Although tumor associated or glioma stem cell derived vasculature has been described as important for tumor formation and progression, the NVP appears to be stem-like. To our knowledge, this population has not been described in GBM. We validated the existence of this NVP with immunofluorescence and fluorescent activated cell sorting from patient tumors followed by single-cell RNA-sequencing. Using a novel organoid transplantation model, we employed single-cell lineage barcoding to identify the progeny of patient-derived NVP cells, determining that they result in various cell types with diverse morphologies. Exploration of data from more traditional model systems including gliomaspheres and mouse GBM models indicate preservation of this NVP identity across systems. We hypothesize that NVP cells may play important roles in tumor plasticity, and thus may be a valuable therapeutic target to explore.