Figure 2.

Colony formation assay upon treatment of HNSCC cell lines with osimertinib, DHA or the double combination. (A) FaDu and CAL27 cells were grown in six-well plates (1,000 cells/well) for 24 hours and then left untreated or treated with osimertinib, DHA and the double combination. After 72 hours, media was replaced with fresh media without drugs. After 7 more days cells were washed and stained with crystal violet and then photographed. The crystal violet was extracted and assayed by spectrophotometry. The absorbance was measured at 570 nm. Osimertinib was used at 0.02 µM and DHA at 20 µM. Images are representative of at least three independent experiments. (B) Quantification of the colonies treated with the indicated concentrations of osimertinib, DHA, and osimertinib plus DHA in A. Values are relative to those of dimethyl sulfoxide-treated (control) cells and represent the mean ± standard deviation from three independent experiments. Statistical significance was assessed by one-tailed t-test. P value was calculated comparing all conditions (control, osimertinib alone, DHA alone) with osimertinib + DHA. DHA, dihydroartemisinin; HNSCC, head and neck squamous cell carcinoma.