Sodium arsenite induces ROS-dependent autophagic cell death in pancreatic β-cells

Inorganic arsenic is a worldwide environmental pollutant. Inorganic arsenic's positive relationship with the incidence of type 2 diabetes mellitus arouses concerns associated with its etiology in diabetes among the general human population. In this study, the inhibitor of autophagosome formation, 3-methyladenine, protected the cells against sodium arsenite cytotoxicity, and the autophagy stimulator rapamycin further decreased the cell viability of sodium arsenite-treated INS-1 cells. These finding suggested the hypothesis that autophagic cell death contributed to sodium arsenite-induced cytotoxicity in INS-1 cells. Sodium arsenite increased the autophagosome-positive puncta in INS-1 cells observed under a fluorescence microscope, and this effect was confirmed by the elevated LC3-II levels detected through Western blot. The LC3 turnover assay indicated that the accumulation of autophagosomes in the arsenite-treated INS-1 cells was due to increased formation rather than impaired degradation. The pretreatment of INS-1 cells with the ROS inhibitor MAC reduced autophagosome formation and reversed the sodium arsenite cytotoxicity, indicating that sodium arsenite-induced autophagic cell death was ROS-dependent. In summary, the precise molecular mechanisms through which arsenic is related to diabetes have not been completely elucidated, but the ROS-dependent autophagic cell death of pancreatic beta-cells described in this study may help to elucidate the underlying mechanism. (C) 2014 Elsevier Ltd. All rights reserved.