Thr3/Ser90 phosphorylation-stabilized S100A8 regulates cholesterol metabolism in glioblastoma stem cells.

Glioblastoma (GBM) exhibits profound therapy resistance and inevitable recurrence, driven predominantly by glioblastoma stem cells (GSCs). S100A8 is positively associated with glioblastoma malignancy, but its expression and molecular mechanism in GSCs are poorly understood. Here, we demonstrated that S100A8 was highly expressed in GSCs and closely associated with shorter overall survival in GBM patients. The results showed that S100A8 maintained GSCs stemness by promoting cholesterol synthesis. Mechanistically, S100A8 bound to plasma membrane-localized RAGE, triggering ROS generation. Elevated ROS oxidized intracellular S100A8 at the Cys42 residue, thereby enhancing its affinity for mTORC1, subsequently inducing SREBP2-driven cholesterol synthesis. Furthermore, ROCK1-mediated phosphorylation of S100A8 at Thr3/Ser90, which stabilized S100A8 by impairing its binding to Fbxo10 and inhibiting the subsequent ubiquitination-mediated degradation. Our study reveals the S100A8-ROS-mTORC1 axis as a cholesterol metabolic vulnerability in GSCs, providing new insights into cholesterol metabolism and highlighting novel metabolism therapeutic strategies in GBM.