Figure 1.

Concurrent use of metformin sensitized TKI-resistant cells to EGFR-TKIs. (A) PC9R and PC9R/OR cells were incubated with indicate concentration gradient of osimertinib for 72 h. (B) PC9R and PC9R/OR cells were incubated with 5 mM metformin alone for 72 h. (C) PC9R cells were treated with indicate concentration gradient of gefitinib with or without 5 mM metformin for 72 h. (D) PC9R/OR cells were treated with indicate concentration gradient of osimertinib with or without 5 mM metformin for 72 h. Cell proliferation was measured by CCK8 assay. The bar graph reveals the IC₅₀ values of TKI for the cells. Each data point represents the average value of six samples and is expressed as a percentage of the surviving cells relative to the untreated controls.