Mitochondrial reverse electron transport regulates glioma stemness through Sirt3-HIF1α-SOX2 signaling

Glioblastoma multiforme (GBM) is an aggressive primary brain tumor characterized by high recurrence and resistance to current therapies, largely driven by glioma stem cells (GSCs). While mitochondrial dysfunction has been implicated in GBM, the specific mitochondrial mechanisms that sustain GSC maintenance remain poorly defined. Here, we identify mitochondrial reverse electron transport (RET) as a key metabolic program enriched in GSCs relative to differentiated glioma cells. Pharmacological inhibition of RET markedly suppresses GSC sphere formation by downregulating the stemness-associated transcription factor SOX2. Mechanistically, RET inhibition increases the NAD⁺/NADH ratio, leading to activation of the NAD⁺-dependent mitochondrial deacetylase SIRT3. Elevated SIRT3 promotes proteasomal degradation of HIF-1α, resulting in transcriptional repression of SOX2. Importantly, RET inhibition significantly prolongs survival in an orthotopic GBM mouse model and suppresses tumor phenotypes in a Notch-driven Drosophila brain tumor model, demonstrating conserved in vivo relevance. Together, these findings establish mitochondrial RET as a critical regulator of GSC maintenance and identify RET targeting as a promising therapeutic strategy for GBM.