Gefitinib inhibits glycolysis and induces programmed cell death in non-small cell lung cancer cells

Abstract

To observe the cell death pattern induced by gefitinib in non-small cell lung cancer A549 and H1975 cells and explore the possible mechanism in light of glycolysis. The inhibitory effects of gefitinib at 20, 30, or 40 μmol/L in A549 cells and at 20, 40, or 80 μmol/L in H1975 cells were examined using MTT assay. The changes of lactic acid level in the cells were determined with a lactic acid kit, and the expression levels of glycolysis-related proteins (PKM2 and HK2) and the proteins in PI3K-Akt-mTOR signaling pathway were detected using Western blotting. 2-NBDG was used for detecting glucose uptake capacity of the cells, and ATP kit was used to detect the intracellular ATP level. The mitochondrial membrane potential of the cells was examined with the JC-1 kit, and cell apoptosis was analyzed with Annexin V-FITC/PI double staining. The relative expression levels of the apoptotic proteins Bax and Bcl-2 and the autophagy marker protein LC3B were detected with Western blotting. MTT assay showed that gefitinib inhibited the proliferation of A549 and H1975 cells in a time- and dose-dependent manner (P < 0.05). The IC50 of gefitinib at 24, 48 and 72 h was 48.6, 28.6 and 19.7 μmol/L in A549 cells and was 321.6, 49.1 and 14.6 μmol/L in H1975 cells, respectively. Gefitinib significantly lowered intracellular lactic acid level of the cells (P < 0.05) and down-regulated the expressions of PKM2 and HK2 proteins (P < 0.05) and PI3K-Akt-mTOR signaling pathway-associated proteins (P < 0.05). Gefitinib obviously inhibited glucose uptake and ATP levels in both A549 and H1975 cells (P < 0.05). Treatment with gefitinib induced obviously enhanced apoptosis in the cells, resulting in apoptosis rates of (10.77± 1.0)%, (14.5±0.4)%, (17.4±0.2)% and (32.1±0.6)% at 0, 20, 30 and 40 μmol/L in A549 cells (P < 0.05) and of (10.5±0.6)%, (13.2± 0.92)%, (18.9±0.98)% and (35.1±1.4)% at 0, 20, 40 and 80 μmol/L in H1975 cells, respectively (P < 0.05). The protein expression of Bax increased and that of Bcl-2 decreased following gefitinib treatment in the cells (P < 0.05). Gefitinib significantly increased autophagy in A549 and H1975 cells as shown by increased LC3B expressions following the treatment (P < 0.05). Gefitinib can inhibit the proliferation, induce apoptosis and increase autophagy in A549 and H1975 cells. Gefitinib induces apoptosis of the cells possibly by affecting glycolysis and PI3K-Akt-mTOR signaling pathway.