Multimodal Single-Cell Analysis Reveals Two Distinct Radioresistant Stem-like and Progenitor Cell Populations in Murine Glioma

Radiation therapy is part of the standard of care for gliomas and kills a subset of tumor cells, while also altering the tumor microenvironment. Previous work shows that tumor cells with stem-like properties preferentially survive radiation and give rise to glioma recurrence. Various techniques for enriching and quantifying cells with stem-like properties have been used, including the fluorescence activated cell sorting (FACS)-based side population (SP) assay, which is a functional assay that enriches for stem-like tumor cells. In these analyses, mouse models of glioma have been used to understand the biology of this disease and the therapeutic response, including the biology of the radiation response. We present here an analysis of combined SP and single-cell RNA sequencing of genetically-engineered mouse models of glioma to show a time course of cellular response to radiation. We identify and characterize two distinct tumor cell populations that are inherently radioresistant. In addition, we identify and characterize distinct effects of radiation on immune cell populations within the tumor microenvironment. We applied sciRNA-seq to 15 archived, frozen samples, which consisted of normal brain and tumor-containing hemisphere for each of 3 treatment conditions: no IR and 8 ± 2 hours and approximately 72 hours after 10Gy