Olig1/2 Drive Astrocytic Glioblastoma Proliferation Through Transcriptional Co-Regulation of Various Cyclins.

As the most aggressive primary brain tumor, glioblastoma (GBM) is considered incurable due to its molecular heterogeneity and therapy resistance. Identifying key regulatory factors in GBM is critical for developing effective therapeutic strategies. Based on the analysis of TCGA data, we confirmed a robust co-expression and correlation of OLIG1 and OLIG2 in human GBM. However, their roles in the astrocytic GBM subtype remain unclear. In this study, we first establish an astrocytic-featured GBM mouse model by introducing PiggyBac-driven hEGFRvIII plasmids and demonstrate that both OLIG1 and OLIG2 are highly expressed within this context. Next, using CRISPR/Cas9 technology to knockout Olig1/2, we found that astrocyte differentiation markers such as GFAP, SOX9, and HOPX were preserved, but tumor cell proliferation was significantly diminished. Mechanistically, CUT&Tag-seq revealed that OLIG1/2 directly binds to the promoter region of various cyclins (Cdk4, Ccne2, Ccnd3, and Ccnd1), where an enrichment of the active histone marker H3K4me3 was observed, indicating transcriptional activation of the genes. Notably, Olig1/2 knockout did not suppress tumor initiation or migration, suggesting that their primary role is to amplify proliferation rather than to drive tumorigenesis. This study defines Olig1 and Olig2 as master regulators of GBM proliferation through various cyclins, thereby offering a novel therapeutic target.