Induction of tumor-initiating cells and glioma-initiating cells from fetal neural stem cells through p53 genome editing

The elucidation of the properties of malignant glioma and development of therapeutic methods require model cells with characteristics such as invasiveness, multinuclearity, and ability for mitosis. A previous study has shown that overexpression of active HRas (HRasL61) in neural stem/progenitor cells isolated from fetal telencephalic neuroepithelial cells with homozygous deletion of the p53 locus forms glioma-initiating cells (GICs). The orthotopically transplantation of 10 cells into the forebrain of immunodeficient mice, resulted in the development of glioblastoma multiforme-like malignant brain tumors. In this study, GICs were induced from wild-type fetal neural stem/progenitor cells. Through forced expression of CRISPR-associated protein 9 together with a guide RNA that recognizes the p53 gene, neural stem/progenitor cells containing p53 knockout cells were obtained. Furthermore, HRasL61 was forced-expressed and transplanted into the immunodeficient mice. These cells were tumor-initiating cells (TICs) with tumorigenicity in the brain. However, no invasiveness to the brain was observed. The p53 homozygous-deleted cells obtained through single-cell cloning from TICs were GICs, forming glioblastoma multiforme-like tumors. The induced GICs strongly expressed the GIC marker. These results indicate that GICs can be induced through genetic recombination using genome editing. This study suggests that the use of genome editing may lead to the elucidation of the oncogenic mechanisms of human cells that cannot delete genes.