Canagliflozin ameliorates high glucose-induced apoptosis in NRK-52E cells via inhibiting oxidative stress and activating AMPK/mTOR-mediated autophagy

Background Sodium-glucose cotransporter-2 (SGLT-2) inhibitors, as a new type of hypoglycemic drug, can prevent proximal renal tubule injury related to glucose toxicity and play a renoprotective role. Canagliflozin, a recognized SGLT-2 inhibitor, has been proved to have potential protection in diabetic nephropathy (DN), but its mechanism has not been fully elucidated. In this study, the protective effect of canagliflozin against high glucose (HG)-induced renal tubular epithelial cell (NRK-52E) injury in vitro was assessed. Methods The viability and apoptosis of NRK-52E cells were detected using cell counting kit-8 (CCK-8) assay and flow cytometry analysis, respectively. The expression levels of cleaved caspase-3, oxidative stress-related proteins (NOX4 and Nrf2), autophagy marker light chain 3 (LC3) I/II, and adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signaling pathway-related proteins were evaluated by Western blot. Reactive oxygen species (ROS) level was evaluated by dihydroethidium (DHE) reactive oxygen species assay, the activities of SOD, CAT, GSH-Px and MDA were analyzed using kits. The changes of morphology and red fluorescent protein (RFP)-LC3 fluorescence were observed under microscopy. Results Canagliflozin significantly ameliorated HG-induced NRK-52E cell apoptosis and caspase-3 cleavage. Furthermore, canagliflozin markedly ameliorated HG-induced NRK-52E cell oxidative stress. Moreover, canagliflozin significantly increased LC3-II levels and induced RFP-LC3-containing punctate structures in NRK-52E cells. Finally, canagliflozin increased the phosphorylation of AMPK and suppressed the phosphorylation of mTOR. The AMPK inhibitor compound C abolished canagliflozin-induced autophagy activation, as well as the anti-apoptotic effect of canagliflozin. Conclusion Canagliflozin effectively ameliorate HG-induced apoptosis of NRK-52E cells in vitro that involved its antioxidant effect and induction of autophagy through the AMPK/mTOR pathway.