KATP Channel Expression Determines ONC212 Sensitivity via Mitochondrial Dysfunction and PERK/ATF4/CHOP Activation in Glioblastoma.
Glioblastoma (GBM) exhibits profound metabolic plasticity and resistance to conventional therapies, partly driven by mitochondrial adaptability and stress response mechanisms. ONC212, a second-generation imipridone, targets mitochondrial proteostasis, yet determinants of tumour sensitivity remain unclear. This study aimed to investigate whether ATP-sensitive potassium (KATP) channel expression modulates ONC212-induced mitochondrial dysfunction and integrated stress response (ISR) activation in GBM. Human GBM lines (U87, U251, T98G) and non-malignant SVG p12 astrocytes received ONC212 (0.5-80 μM) for 12-48 h. Viability was assessed by CCK-8. KATP subunit expression (Kir6.2, SUR1, CCDC51) was quantified by qRT-PCR and western blot. Mitochondrial ROS quantification, oxygen consumption rate (Seahorse XF), PERK/ATF4/CHOP activation (western blot, immunofluorescence) and apoptosis (caspase-3/7) were evaluated. KATP was modulated pharmacologically (glibenclamide, diazoxide) and via KCNJ11 (Kir6.2) siRNA. ONC212 induced time-dependent and tumour-selective cytotoxicity, with highest sensitivity observed in KATP-high U87 cells. Treatment significantly increased mitochondrial ROS, impaired oxidative phosphorylation and reduced ATP/ADP ratios, indicating bioenergetic collapse. Concurrently, ONC212 robustly activated the PERK/eIF2α/ATF4/CHOP axis and promoted ATF4 nuclear translocation. PERK inhibition attenuated both stress signalling and cytotoxicity, confirming ISR dependency. KATP inhibition enhanced ONC212-induced mitochondrial dysfunction, ISR activation and apoptosis, whereas KATP activation exerted protective effects. Importantly, KCNJ11 silencing markedly potentiated ONC212 sensitivity, amplifying ROS production, mitochondrial impairment and caspase-dependent apoptosis. KATP channel expression may regulate ONC212 responsiveness in GBM by modulating mitochondrial stress and ISR signalling. Targeting KATP channels may enhance imipridone efficacy and represents a promising strategy for metabolically guided GBM therapy.