Fig. 2

Hyposensitivity to EGFR-TKI after the treatment of EGFR-sensitive NSCLC cell lines with OA (a) The indicated NSCLC cell lines were exposed to varying concentrations (0, 1 μM, 10 μM, 100 μM, and 1000 μM) of OA with vehicle (DMSO, NT) or Gefitinib (15 μM or 20 μM in H1975 cells) for 2 days, and the relative OD value was assessed to determine cell viability by the CCK-8 assay. Data represent the mean ± SD of three replicate determinations. b Up panel, the cells were stained with Nile red 48 h after vehicle (DMSO, NT), Gefitinib (100 nM or 20 μM in H1975 cells), or Gefitinib (100 nM) + OA (100 μM) treatment. Down panel, lipid accumulation of indicated cell lines was evaluated by measuring Nile red fluorescence by flow cytometry; data are expressed as the percentage of level found in control cells (H1975 DMSO) and are the means ± SD of at least 3 independent experiments. *p < 0.05, **p < 0.01, when compared to control cells. c Up panel, HCC827, PC9 and H1975 cells were stained with BODIPY 493/503 (green) and anti-p-EGFR1086 antibody (red) and counterstained with Hoechst (blue) after 48 h of exposure to vehicle (DMSO, NT), Gefitinib (100 nM or 20 μM in H1975 cells), or Gefitinib (100 nM) + OA (100 μM). Down panel, quantitation of p-EGFR expression of indicated cell lines. d Up panel, Edu staining was used to quantify the inhibition of cell proliferation. The indicated NSCLC cell lines were seeded and exposed to vehicle (DMSO, NT), Gefitinib (100 nM or 20 μM in H1975 cells), or Gefitinib (100 nM) + OA (100 μM) for 48 h and stained for Edu. Down panel, the proliferation rate was determined by counting the proliferating cells using ImageJ software. p values were determined by one-way ANOVA. *p < 0.05, **p < 0.01, ***p < 0.001. Data represent the mean ± SD of three replicate determinations