Glipizide sensitizes lung cancer cells to TRAIL-induced apoptosis via Akt/mTOR/autophagy pathways

The combination of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) with subsidiary agents is a promising anticancer strategy to conquer TRAIL resistance in malignant cells. Glipizide is a second-generation oral hypoglycemic medicine for the cure of type II diabetes because of its capability to selectively stimulate insulin secretion from β-cells. In this study, we revealed that glipizide could trigger TRAIL-mediated apoptotic cell death in human lung adenocarcinoma cells. Pretreatment with glipizide downregulation of p-Akt and p-mTOR in different concentrations. In addition, LC3-II and p-Akt was suppressed in the presence of LY294002, a well-known inhibitor of P13K. Treatment with glipizide commenced in a slight increase in conversion rate of LC3-I to LC3-II and significantly decreased p62 expression levels in a dose-dependent manner. This indicates that glipizide encouraged autophagy flux activation in human lung cancer cells. Inhibition of autophagy flux applying a specific inhibitor and genetically modified ATG5 siRNA enclosed glipizide-mediated enhancing effect of TRAIL. These data demonstrate that inhibition of Akt/mTOR by glipizide sensitizes TRAIL-induced tumor cell death through activating autophagy flux and also suggest that glipizide may be a combination therapeutic target with TRAIL protein in TRAIL-resistant cancer cells.