Abstract
Ionizing radiation, a standard therapeutic approach for lung cancer, often leads to cellular senescence and the induction of epithelial-mesenchymal transition (EMT), posing significant challenges in treatment efficacy and cancer progression. Overcoming these obstacles is crucial for enhancing therapeutic outcomes in lung cancer management. This study investigates the effects of ionizing radiation and gemcitabine on lung cancer cells, with a focus on induced senescence, EMT, and apoptosis. Human-derived A549, PC-9, and mouse-derived Lewis lung carcinoma cells exposed to 10 Gy X-ray irradiation exhibited senescence, as indicated by morphological changes, β-galactosidase staining, and cell cycle arrest through the p53-p21 pathway. Ionizing radiation also promoted EMT via TGFβ/SMAD signaling, evidenced by increased TGFβ1 levels, altered EMT marker expressions, and enhanced cell migration. Gemcitabine, a first-line lung cancer treatment, was shown to enhance apoptosis in senescent cells caused by radiation. It inhibited cell proliferation, induced mitochondrial damage, and triggered caspase-mediated apoptosis, thus mitigating EMT in vitro. Furthermore, in vivo studies using a lung cancer mouse model revealed that gemcitabine, combined with radiation, significantly reduced tumor volume and weight, extended survival, and suppressed malignancy indices in irradiated tumors. Collectively, these findings demonstrate that gemcitabine enhances the therapeutic efficacy against radiation-resistant lung cancer cells, both by inducing apoptosis in senescent cells and inhibiting EMT, offering potential improvements in lung cancer treatment strategies.