ANGI-06. BIOLOGY OF GLIOBLASTOMA INVASION: A SINGLE-CELL LEVEL ANALYSIS OF TUMOR CORE VS. INFILTRATING EDGE

Abstract

Abstract Glioblastoma (GBM) is a highly proliferative and diffusely infiltrating tumor, consisting of a necrotic core showing extensive microvascular proliferation and an infiltrating edge that extends beyond the surgical resection margin. The aggressiveness of GBM can be attributed to the existence of glioma stem-like cell populations (GSC) at this infiltrating edge. Although many studies have characterized GSC biology in culture, their contributions to invasion in vivo, and in the context of their microenvironment, remains poorly understood. In this study, we used macro-dissected biopsies of the tumor core and the infiltrative edge from six genetically-distinct glioblastoma tumors, to generate a spatiotemporal map of tumor invasion at a single-cell level. Unbiased clustering of ~40,000 nuclei and integrated analysis identified various cell types composing the tumor microenvironment, with predominance of tumor cells at the core and non-neoplastic cells at the edge, as expected. Inferred copy number alterations based on gene expression confirmed tumor cell identity in the core and the edge datasets. Differential expression analysis of core vs. edge tumor clusters revealed distinct transcriptomic signatures including several genes previously implicated in GBM invasion, such as EGFR, matrix metalloproteinases, and MAPK signaling pathway members. Several genes from this newly defined “GBM invasion signature” were further validated in a PDX invasion model, in which the transcriptome within the tumor core and infiltrative edge were similarly sequenced and analyzed at the single cell level. We are currently employing 10X-visium combined with immunohistochemistry to spatially deconvolute and corroborate the defined GBM invasion/infiltration signature at the tissue level in tumor biopsies. Overall, our study aims to provide high resolution map of glioma tumor invasion that can prioritize new and unique targetable pathways.