Hyperbaric Oxygen Reverses High-Glucose-Induced Stemness and Radioresistance in Non-Small Cell Lung Cancer Cells

Hyperglycemia may promote aggressive phenotypes and treatment resistance in non-small cell lung cancer (NSCLC). We investigated whether chronic high glucose (HG) exposure induces stem cell-like properties and radioresistance and whether hyperbaric oxygen (HBO) reverses these effects.

H1299 and A549 cells were maintained under normal glucose (NG; 5.5 mM D-glucose) or high glucose (HG; 25 mM D-glucose) conditions. Acute effects were evaluated by switching NG-grown cells to NG or HG and performing MTT assays. For all other experiments, cells were conditioned in HG for 3 months. Protein expression of glucose transporter-1 (Glut1), hypoxia-inducible factor-1α (HIF-1α), CD133, SOX2, and OCT4 was assessed by immunoblotting. Stem-like behavior and radiosensitivity were evaluated by tumorsphere formation and clonogenic survival assays following irradiation. HBO (100% O₂, 1.5 ATA, 90 min/session, once daily) was applied as indicated.

Acute HG increased cell viability, whereas long-term HG conditioning did not significantly alter short-term viability but increased tumorsphere formation and clonogenic survival after irradiation. HG upregulated Glut1 and HIF-1α and increased SOX2 and OCT4 expression. Additional analyses showed that 4 weeks, but not 1 week, of continuous HBO exposure reduced HIF-1α, SOX2, and OCT4 expression under HG conditions, whereas Glut1 expression was not markedly altered. HBO suppressed HG-enhanced tumorsphere formation and reversed HG-associated radioresistance.

Chronic HG promoted stem-like and radioresistant phenotypes in NSCLC cells. Prolonged HBO exposure for 4 weeks attenuated these effects and was associated with reduced HIF-1α, SOX2, and OCT4 expression, supporting HBO as a potential preclinical adjunct strategy for mitigating HG-associated therapeutic resistance.