Background: In conditions of diabetes, exosomes have been suggested to play the roles in the pathological processes in both type 1 and type 2 diabetes. Exosomes released from both high-concentration glucose- and cytokine-treated β-cells induced β-cell apoptosis. Pancreatic cancer-derived exosomes have also been found to cause paraneoplastic β-cell dysfunction. Here, we further investigated the effects and mechanisms of insulinoma β-cell-derived exosomes on glucose-stimulated insulin secretion.
Methods: Exosomes from insulinoma β-cell lines RIN-m5f or NIT-1 were prepared by ExoQuick-TC™, and identified its characteristics by Western blotting and nanoparticle tracking analysis. For in vitro study, exosomes at the concentrations of 1-30 μg/mL were used. For in vivo study, ICR mice were treated with PBS or exosomes (30 μg/100 μL) for 4 weeks by tail vein intravenous injection twice a week. The miRNA profile was determined by Next Generation Sequencing (NGS) analysis.
Results: Exosomes from insulinoma β-cells did not affect the cell viability, but significantly inhibited the glucose-stimulated insulin secretion of naïve β-cells. Exogenously administration of exosomes derived from insulinoma β-cells to mice also showed the dysregulation of glucose tolerance and serum insulin levels. Moreover, the results of NGS showed that exosomes may transfer miR-1224, -122-5p, -133a-3p, -10b-5p, -423-5p, -409a-3p to affect insulin secretion-related genes/proteins in β-cells. Exosomes also significantly reduced the protein expressions of phosphorylated Akt, Ca2+/calmodulin-dependent protein kinase-II, and glucose transporter-2 in β-cells, which could be reversed by inhibition of exosome uptake.
Conclusion: Exosomes released from insulinoma β-cells are capable of upregulating exosomal miRNAs-associated signals to dysregulate glucose-stimulated insulin secretion in naïve β-cells.
S. Liu: None. C. Wu: None.
Ministry of Science and Technology of Taiwan (107-2314-B-002-031-MY3)