Enhanced Sensitivity of Nonsmall Cell Lung Cancer with Acquired Resistance to Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitors to Phenformin: The Roles of a Metabolic Shift to Oxidative Phosphorylation and Redox Balance

Figure 5

Reversal of antiproliferation effect of phenformin by glycolysis reactivation. (a) Establishment of hexokinase2 overexpressing H292 ER cells (H292 ER-HK2). H292 ER cells were transfected with pCAG-Flag-HK2-IRES-Blas or pCAG-Flag-IRES-Blas and protein expression was confirmed by immunoblotting. (b) ECAR values in H292 ER-MOCK and H292 ER-HK2 cells. Glycolysis stress test was performed by XFp analyzer, and ECAR was measured and normalized with basal ECAR level. Data represent (, , vs. H292 ER-MOCK). (c) Relative contribution of glycolysis and OXPHOS to ATP production in H292 ER-MOCK and H292 ER-HK2 cells. Using XFp real-time ATP rate assay kit, ATP production rate from glycolysis and OXPHOS was measured in H292 ER-MOCK and H292 ER-HK2 cells. Data represent means (, vs. mito ATP production rate in H292 ER-MOCK). (d) Alleviated antiproliferative effect of phenformin by HK2 overexpression. H292 ER-MOCK and H292 ER-HK2 cells were treated with vehicle or phenformin and cell proliferation rate was monitored for 72 h by IncuCyte ZOOM. Data represent (, vs. H292 ER-MOCK). (e) Schematic illustration for metabolic shift to OXPHOS and the enhanced biguanide responsiveness in acquired EGFR-TKI resistant lung cancer.

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