STEM-24. INTERFERON SIGNALING REGULATES THE PROLIFERATION AND MESENCHYMAL PHENOTYPE OF GLIOBLASTOMA STEM CELLS

Abstract

Abstract Interferon (IFN) signaling contributes to stemness, cell proliferation, cell death, and cytokine signaling in cancer and immune cells; however, the role of IFN signaling in glioblastoma (GBM) and GBM stem-like cells (GSCs) is unclear. This study aimed to investigate the cancer cell-intrinsic IFN signaling in tumorigenesis and malignant phenotype of GBM. We characterized cell-intrinsic IFN signaling in The Cancer Genome Atlas, patient-derived cohorts of GSCs, and published single-cell RNA sequencing datasets by in-silico analyses. The in-silico findings were further validated by evaluating the cytokine secretion and using pharmacological activators and blockers of IFN/transducer and activator of transcription 1 (STAT1) signaling. We found that GSCs and GBM tumors exhibited differential cell-intrinsic IFN signaling, and high IFN/STAT1 signaling is associated with mesenchymal phenotype and poor survival outcomes. Ruxolitinib, a pharmacological inhibitor of IFN/STAT1, abolished the IFN/STAT1 signaling in GSCs with intrinsically high IFN signaling. IFN-γ treatment for 1 week promotes the mesenchymal phenotype in GSCs with low IFN signature. In addition, chronic inhibition of IFN/STAT1 signaling with ruxolitinib decreased cell proliferation and mesenchymal signatures (CD44, YKL40, and TIMP1) in GSCs with intrinsically active IFN/STAT1 signaling. Publicly available human glioma single-cell RNA-seq (scRNA-seq) datasets analyses showed that both tumor and nontumor cells expressed IFN signaling genes, and the mesenchymal signature was highly expressed in the same cluster where IFN signaling genes were upregulated. We demonstrated that cell-intrinsic IFN signaling in GSCs and GBM tumors is associated with mesenchymal signatures and cell proliferation. Our study provides evidence for the possibility of targeting IFN signaling in a specific group of GBM patients.