Radiosensitizing effect of gold nanoparticle loaded with small interfering RNA-SP1 on lung cancer

•siRNA-SP1-loaded AuNPs (AuNPs-si-SP1) inhibits SP1 expression in lung cancer cells.•GZMB expression is elevated by silencing SP1 in lung cancer cells.•AuNPs-si-SP1 combined with radiotherapy inhibits lung cancer growth effectively.•AuNPs-si-SP1 enhances radiosensitivity of lung cancer via SP1/GZMB axis.•AuNPs-si-SP1 provides a novel target for radiotherapy of lung cancer.