Mitochondria-targeted Antioxidant MitoQ Inhibits Cellular Metabolism in Diffuse Midline Glioma

Diffuse midline glioma (DMG) is a malignant pediatric brain tumor with a median survival of <12 months. Radiotherapy is the mainstay of treatment, and there is no effective chemotherapy for DMG. New therapies are needed for the treatment of this deadly disease. Mitoquinone mesylate (MitoQ), a mitochondria-targeting antioxidant has shown some anti-cancer properties. In our preliminary studies, MitoQ inhibited migration and clonogenicity of DMG cells. In the current study, we investigated the effect of MitoQ on cellular metabolism in DMG cells. Patient-derived H3.3K27M mutant DMG (SF8628) cells were grown in DMEM media, supplemented with 10% FBS and L-glutamine, under humidified air with 5% CO2 at 37 °C. When confluent, cells in the test group were treated with MitoQ (2.5 μM). After overnight incubation, cells were harvested and extracted in perchloric acid (PCA). 1H NMR spectroscopic data were collected on cell extracts and metabolomic analysis was performed. We observed a >2-fold decrease (p-value, <0.03) in the levels of branch-chain amino acids (leucine/isoleucine/valine), lactate, glutamate, aspartate, creatine, phosphocreatine, phosphocholine, taurine, and glycine in MitoQ-treated DMG cells compared to the control group. About 74% and 80% decrease were observed in glutamate and aspartate levels in MitoQ-treated cells compared to the untreated group, suggesting that MitoQ almost completely inhibited mitochondrial metabolism of DMG cells. Moreover, lactate also decreased by 55%, suggesting that MitoQ also inhibits glycolysis indirectly. A decrease in creatine and phosphocreatine in MitoQ-treated group suggests that there is a decrease in ATP production by DMG cells. Glycine, taurine and phosphocholine are generally elevated in aggressive cancer cells, a significant decrease in the levels of these metabolites suggests anti-cancer effect of MitoQ on DMG cells. In conclusion, MitoQ inhibits cellular energy metabolism in DMG cells and it may have potential in metabolic therapy for the treatment of DMG tumors.