Abstract
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.