Induction of apoptosis of β cells of the pancreas by advanced glycation end-products, important mediators of chronic complications of diabetes mellitus

We herein report cytotoxicity of advanced glycation end-products (AGEs) on pancreatic β cells. AGEs stimulated reactive oxygen species (ROS) generation but did not arrest proliferation of the INS-1 cell line. Pancreatic β cell lines or primary cultured islets possess a receptor for AGE (RAGE), and its expression increased after AGE treatment. TUNEL staining and FACS analysis using annexin V/PI antibodies showed that apoptosis increased in INS-1 cells or primary cultured islets when incubated with BSA conjugated with glyceraldehyde (AGE2) or glucoaldehyde (AGE3), compared with those conjugated with glucose (AGE1). Reaction of INS-1 cells to Ki67, which is a cellular marker for proliferation, was also increased after AGE treatment. The ability of primary cultured islets to secrete insulin was retained even after AGE treatment under either low or high glucose conditions. The antiserum against RAGE partially prevented AGE-induced cellular events. Treatment of β cells with the antioxidant metallothionein results in a significant reduction in pathologic changes. AGEs might be able to induce apoptosis as well as proliferation of pancreatic β cell lines or primary cultured islets. Moreover, antibody array showed that RAD51 and RAD52 were significantly decreased in AGE2-treated INS-1 cells. AGEs might inhibit homologous DNA recombination for repairing DNA of INS-1 cells damaged by ROS generation. It might be suggested that treatment of AGEs resulted in ROS production and apoptosis through their receptor on pancreatic β cells. AGEs might deteriorate function of pancreatic β cells in patients with long-term hyperglycemia.