Figure 3.

GPX2 overexpression facilitates malignant progression and cisplatin resistance of KRAS-mutated NSCLC cells. (A) SW1573 and NCIH1792 cells were introduced with GPX2 or EV lentivirus, and then lysates were collected for western blotting. (B) SW1573 and NCIH1792 cells (2,500/well) introduced with GPX2 or EV lentivirus were seeded in 96-well plates, and then cell viability was evaluated at days 0, 2, 4, and 6. (C-F) SW1573 and NCIH1792 cells introduced with GPX2 or EV lentivirus were used for (C and D) BrdU incorporation assays and (E and F) Transwell migration and invasion assays. Scale bar, 50 µm for C and E. (G-I) SW1573 cells (2×10⁶) introduced with GPX2 or EV lentivirus were subcutaneously injected into nude mice, and then tumor xenografts were allowed to grow for 4 weeks. (G) Tumor growth curves, (H) representative images and (I) tumor weight are presented. (J) SW1573 and NCIH1792 cells (2,500/well) introduced with GPX2 or EV lentivirus were seeded in 96-well plates and treated with 0, 0.63, 1.25, 2.5, 5, 10, 20, 40, 80 and 160 µM cisplatin for 6 days, and then the relative cell viability was evaluated by CCK-8 assay. (K, L) SW1573 and NCIH1792 cells introduced with GPX2 or EV lentivirus were treated with 2.5 or 10 µM cisplatin for 3 days, and then (K) the cells were stained with Annexin V-FITC for flow cytometry. (L) The percentages of apoptotic cells are presented. (M and N) ROS levels were evaluated by flow cytometry. (M) Oxidative DCF-positive cells and (N) relative FACS values are presented. (O) NADPH/NADP⁺ ratio of SW1573 and NCIH1792 cells introduced with GPX2 or EV lentivirus are shown. ^*P<0.05. GPX2, glutathione peroxidase 2; KRAS, Kirsten rat sarcoma viral oncogene homolog; NSCLC, non-small cell lung cancer; EV, empty vector; BrdU, bromodeoxyuridine; CCK-8, Cell Counting Kit-8; ROS, reactive oxygen species; DCF, dichlorofluorescein; PI, propidium iodide.