Canagliflozin, a SGLT-2 inhibitor, relieves ER stress, modulates autophagy and induces apoptosis in irradiated HepG2 cells: Signal transduction between PI3K/AKT/GSK-3β/mTOR and Wnt/β-catenin pathways; in vitro

Background and Objectives: Metabolic shifting from mitochondrial respiration to glycolysis characterizes malignant cells from its normal counterparts and is attributed to overactivation of oncogenic signaling pathways. Hence, this study intended to investigate the influence of canagliflozin (CAN) and/or gamma-irradiation (gamma-IR) on HepG2 cell proliferation, crosstalk between phosphatidylinositol 3-kinases (PI3K)/AKT/glycogen synthase kinase-3-beta (GSK3-beta)/mTOR and Wnt/beta-catenin signaling pathways, and their regulation of diverse processes, such as endoplasmic reticulum (ER) stress, autophagy, and apoptosis. Materials and Methods: HepG2 cells were treated with different doses of CAN and then exposed to different doses of gamma-IR to achieve optimization that was based on cytotoxicity and clonogenic assays, respectively. The effects of CAN and/or gamma-IR on glycolytic metabolism, cellular bioenergetics, oxidative stress, ER stress and autophagy biomarkers, expression of PI3K/AKT/GSK3-beta/mTOR and Wnt/beta-Catenin signaling pathways, and apoptotic markers were monitored. Results: CAN enhanced the antitumor potential of gamma-IR as displayed by a significant inhibition of clonogenic survival in HepG2 cells via inhibition of glucose uptake, lactate release, and modulation of ER stress-mediated autophagy; switched it to apoptosis; as well as disabled signaling pathways which contribute to metabolic reprogramming and tumor progression induced by gamma-IR that confer radioresistance and treatment failure. Conclusion: Our study sheds light on the effective combination of CAN and gamma-IR in hepatocellular carcinoma treatment and necessitates CAN treatment prior to gamma-IR to overcome metabolic reprogramming-associated radioresistance and improve curative outcomes.