STEM-12. DISCOVERY THE ORIGIN-CELLS FOR HUMAN GLIOBLASTOMA GENESIS IN SUBVENTRICULAR ZONE

Human glioblastoma (GBM), originating from the subventricular zone (SVZ), occurs due to molecular disruptions in chromosomes. Most GBM tissues exhibit definitive chromosomal patterns: copy-number-variations (CNV) in chromosome 7 (gain) and 10 (loss), known as the earliest molecular events. Herein, we hypothesised that the origin-cells in SVZ of GBM patients can provide clues regarding these chromosomal alterations. We compared bulk RNA sequencing (RNAseq) data of GBM tumor tissue (n=126), tumour free GBM SVZ (n=40), and tumor-free control SVZ of non-glial tumor (n=9). Paired single-cell-level RNAseq samples of tumor free GBM SVZ (n=7) and GBM tumor tissue (n=10), were done to see cell specific CNVs. Using human SVZ and GBM samples as a background, we generated origin-cell and origin-cell-derived tumour cell using CRISPR/Cas9. In this work, we identified two GBM-origin-cell types with stem-cell signatures during single-cell level analyses of 60 SVZ tissue samples obtained from tumor-free regions of GBM patients. Furthermore, single-cell level analysis revealed that two origin-cell types in SVZ harbor ongoing patterns of CNV alterations. Among the origin-cells found in the SVZ of GBM patients, NO-like cells showed neural progenitor plus oligodendrocyte progenitor (NO) signature, while AN-like cells showed astrocyte plus neural stem cell (AN) signature. For the interconnectedness, we subjected single-cell-level RNA-seq data to ligand-receptor connection analysis. In the stem cell mode, NO-like cells was connected to AN-like cells in SVZ samples and while in the tumor samples, cycling cell was connected to AN-like cells. NO-like cells was common in TERT promoter wildtype GBM and AN-like cells was more common in TERT promoter mutant GBM. CRISPR/Cas9 models revealed accumulation copy-number alterations from non-tumorigenic origin-cells to tumor cells. These two origin-cells (NO-like cells and AN-like cells) derived from the SVZ of the adult human brain will facilitate the understanding of GBM genesis and development of potential novel therapeutic targets.