Alpha-lipoic acid inhibits sodium arsenite-mediated autophagic death of rat insulinoma cells

Abstract

Aim To investigate the protective effect of α-lipoic acid on sodium arsenite (NaAsO2) induced INS-1 cells injury and its mechanism. Methods The cell viability was measured by CCK-8 assay. The autophagosomes was observed under transmission electron microscopy. The autophagosomes in cells transfected with green fluorescent protein microtubule-associated protein light chain 3 (GFP-LC3) plasmids were observed under a laser scanning con-focal microscope. The expression of LC3-II, P62, PI3K, and mTOR proteins in INS-1 cells treated with a combination of chloroquine (CQ, autophagy inhibitor) and NaAsO2 were detected by Western blot assay. The expression of LC3-II, P62, PI3K, and mTOR proteins were detected in INS-1 cells treated with a combination of rapamycin (autophagy inducer, mTOR inhibitor) and α-LA. Results The cytotoxicity induced by NaAsO2 was reversed by α-LA, and the viability of NaAsO2-treated INS-1 cells increased. α-LA pretreatment decreased the autophagosome accumulation induced by NaAsO2. α-LA also reduced the fluorescence spot aggregation of GFP-LC3 in INS-1 cells exposed to NaAsO2 as observed under a laser scanning con-focal microscope. α-LA inhibited NaAsO2 induced autophagy by up-regulating PI3K and mTOR and down-regulating LC3-II and P62. CQ inhibited NaAsO2 induced autophagy by up-regulating PI3K, mTOR, P62 and down-regulating LC3-II. α-LA inhibited rapamycin-induced autophagy by up-regulating PI3K, mTOR and P62 and down-regulating LC3-II. The results showed that NaAsO2 could induce autophagy activation in INS-1 cells. The α-LA may inhibit autophagy activation by regulating the PI3K/mTOR pathway. Conclusion The data indicated that α-LA might inhibit the NaAsO2-induced autophagic death of INS-1 cells by regulating the PI3K/mTOR pathway.