Ketone pretreatment reduces superoxide production in human U87 glioblastoma cells exposed to normoxia and hyperoxia

Abstract

Unlike normal brain cells, cancer cells lack the metabolic flexibility to use ketones as fuel. Brain cancer cells have defective mitochondria and derive energy primarily through aerobic glycolysis (the Warburg effect). Cancer growth is intimately linked to glucose‐stimulated reactive oxygen species (ROS) production. We hypothesized that ketones would reduce mitochondrial ROS production in cultured human U87 glioblastoma cells. Fluorescence microscopy and confocal spectral imaging were used to detect real‐time intracellular superoxide production with dihydroethidium (DHE). Cultured U87 cells were maintained in media containing 1mM glucose in the presence or absence of 2‐10mM D‐beta‐hydroxybutyrate (BHB) for 4‐6 days. Results demonstrate that superoxide production (measured as DHE fluorescence intensity units; FIU) was approximately 300% higher in untreated cells versus BHB‐treated cells (2 mM). Measurement of superoxide production during normoxia (60 minutes) increased FIUs 49 ± 3, 14 ± 2 and 38 ± 2 in untreated, 2mM and 10mM BHB, respectively. Hyperoxia‐induced mitochondrial superoxide production was abolished in U87 cells pretreated with 2mM BHB. We conclude that supplemental ketones significantly reduce superoxide production in U87 cells. These results suggest that supplemental ketones may confer protection against malignant brain cancer.