title: Metformin inhibits advanced glycation end products (AGEs)-induced renal tubular cell injury by suppressing reactive oxygen species generation via reducing receptor for AGEs (RAGE) expression.
abstract: Advanced glycation end products (AGEs) and their receptor (RAGE) play a role in tubulointerstitial damage in diabetic nephropathy. Recently, metformin has been shown to ameliorate tubular injury both in cell culture and diabetic animal model. However, effects of metformin on AGEs-induced tubular cell apoptosis and damage remain unknown. We examined here whether and how metformin could block the AGEs-RAGE-elicited tubular cell injury in vitro. Gene expression level was evaluated by real-time reverse-transcription polymerase chain reactions. Reactive oxygen species (ROS) generation was measured with dihydroethidium staining. Apoptosis was evaluated by DNA fragmentation and annexin V expression level. AGEs upregulated RAGE mRNA levels and subsequently increased ROS generation and intercellular adhesion molecule-1, monocyte chemoattractant protein-1 and transforming growth factor-β gene expression in human renal proximal tubular cells, all of which were significantly blocked by the treatment of 0.01 and 0.1 mM metformin. Compound C, an inhibitor of AMP-activated protein kinase significantly blocked the effects of metformin on RAGE gene expression and ROS generation in AGEs-exposed tubular cells. Furthermore, metformin dose-dependently inhibited the AGEs-induced apoptotic cell death of tubular cells; 1 mM metformin completely suppressed the pro-apoptotic effects of AGEs in 2 different assay systems. Our present study suggests that metformin could inhibit the AGEs-induced apoptosis and inflammatory and fibrotic reactions in tubular cells probably by reducing ROS generation via suppression of RAGE expression through AMP-activated protein kinase activation. Metformin may protect against tubular cell injury in diabetic nephropathy by blocking the AGEs-RAGE-ROS axis.
authors.affiliation: Department of Pathophysiology and Therapeutics of Diabetic Vascular Complications, Kurume University School of Medicine, Kurume, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ishibashi
authors.forename: T
authors.initials: T
authors.lastname: Matsui
authors.forename: M
authors.initials: M
authors.lastname: Takeuchi
authors.forename: S
authors.initials: S
authors.lastname: Yamagishi
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D003928:Diabetic Nephropathies / Q000517:prevention & control; D017127:Glycation End Products, Advanced / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D007004:Hypoglycemic Agents / Q000037:antagonists & inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008687:Metformin / Q000037:antagonists & inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D058990:Molecular Targeted Therapy; D009994:Osmolar Concentration; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: C111835:CCL2 protein, human; D018932:Chemokine CCL2; D017127:Glycation End Products, Advanced; D007004:Hypoglycemic Agents; C573420:ICAM1 protein, human; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; D016212:Transforming Growth Factor beta; D018799:Intercellular Adhesion Molecule-1; D008687:Metformin; D055372:AMP-Activated Protein Kinases