Abstract
Statins are used extensively for the clinical treatment of cardiovascular diseases. Recent studies suggest that statins increase the risk of new-onset diabetes mellitus (NODM). However, the mechanisms of statin-induced NODM remain unclear. The present study investigated the effects of autophagy on insulin secretion impairment induced by rosuvastatin (RS) in rat insulinoma cells (INS-1E) cells. INS-1E cells were cultured and treated with RS at different concentrations (0.2-20 μM) for 24 h. Insulin secretion in INS-1E cells was detected by enzyme-linked immunosorbent assay, and the co-localization of microtubule-associated protein light chain 3 (LC3) and lysosome-associated membrane protein 2 (LAMP-2) was observed by immunofluorescence staining. Western blotting was used to assess the conversion of LC3 and p62. The results showed that the insulin secretion and cell viability decrease induced by RS treatment for 24 h occurred in a dose-dependent manner in INS-1E cells. RS significantly inhibited the expression of LC3-II but increased the protein expression of p62. Simultaneously, RS diminished the co-localization of LC3-II and LAMP-2 fluorescence signals. These results suggested that RS-inhibited autophagy in INS-1E cells. Rapamycin, an autophagy agonist, reversed the insulin secretion and cell viability suppression induced by RS in INS-1E cells. RS also decreased the phosphorylation of the mammalian target of rapamycin (mTOR). The results indicated that RS impairs insulin secretion in INS-1E cells, which may be partly due to the inhibition of autophagy via an mTOR-dependent pathway.