Everolimus regulates the activity of gemcitabine-resistant pancreatic cancer cells by targeting the Warburg effect via PI3K/AKT/mTOR signaling

Abstract

Background Gemcitabine (GEM) resistance remains a significant clinical challenge in pancreatic cancer treatment. Here, we investigated the therapeutic utility of everolimus (Evr), an inhibitor of mammalian target of rapamycin (mTOR), in targeting the Warburg effect to overcome GEM resistance in pancreatic cancer. Methods The effect of Evr and/or mTOR overexpression or GEM on cell viability, migration, apoptosis, and glucose metabolism (Warburg effect) was evaluated in GEM-sensitive (GEM sen ) and GEM-resistant (GEM res ) pancreatic cancer cells. Results We demonstrated that the upregulation of mTOR enhanced cell viability and favored the Warburg effect in pancreatic cancer cells via the\xa0regulation of PI3K/AKT/mTOR\xa0signaling. However, this effect was counteracted by Evr, which inhibited aerobic glycolysis by reducing the levels of glucose, lactic acid, and adenosine triphosphate and suppressing the expression of glucose transporter 1, lactate dehydrogenase-B, hexokinase 2, and pyruvate kinase M2 in GEM sen and GEM res cells. Evr also promoted apoptosis by upregulating the pro-apoptotic proteins Bax and cytochrome-c and downregulating the anti-apoptotic protein Bcl-2. GEM was minimally effective in suppressing GEM res cell activity, but the therapeutic effectiveness of Evr against pancreatic cancer growth was greater in GEM res cells than that in GEM sen cells. In vivo studies confirmed that while GEM failed to inhibit the progression of GEM res tumors, Evr significantly decreased the volume of GEM res tumors while suppressing tumor cell proliferation and enhancing tumor apoptosis in the presence of GEM. Conclusions Evr treatment may be a promising strategy to target the growth and activity of GEM-resistant pancreatic cancer cells by regulating glucose metabolism via inactivation of PI3K/AKT/mTOR signaling.