Dihydroartemisinin enhances gefitinib cytotoxicity against lung adenocarcinoma cells by inducing ROS-dependent apoptosis and ferroptosis.

The application of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), such as gefitinib, has shifted lung cancer treatment from empirical chemotherapy to targeted molecular therapy. However, acquired drug resistance is inevitable in almost all non-small cell lung cancer (NSCLC) patients treated with gefitinib. Combined treatment with dihydroartemisinin (DHA) and gefitinib produced a better inhibitory effect on lung adenocarcinoma than gefitinib treatment alone; however, the specific mechanism remains unclear. In this study, we aimed to assess the underlying mechanism of this combination treatment. We prepared gefitinib-resistant A549 cells and investigated whether apoptosis and ferroptosis were involved in the sensitizing effect of DHA. Treatment with 5 μM gefitinib resulted in rupturing and floatation of A549 cells in the medium, while A549-GR cells were found to be insusceptible to gefitinib. However, treatment with DHA substantially inhibited the proliferation of A549-GR cells in a dose-dependent manner accompanied by increased apoptosis and ferroptosis. The accumulated reactive oxygen species (ROS) was crucial for the inhibitory effect of DHA on A549-GR cells. Moreover, cellular autophagy was significantly upregulated post-DHA treatment. The combined treatment of DHA and gefitinib resulted in inhibition of proliferation of A549, H1975, and HCC827 cells, and ROS accumulation and a remarkable induction of apoptosis was observed in A549-GR cells. DHA significantly induced apoptosis and ferroptosis in a dose-dependent manner and exhibited high cellular toxicity on A549-GR cells when combined with gefitinib.