Exosome-mediated miR-200a delivery into TGF-β-treated AGS cells abolished epithelial-mesenchymal transition with normalization of ZEB1, vimentin and Snail1 expression

Abstract

Exosomes are small extracellular vesicles that can be derived from human cells such as mesenchymal stem cells (MSCs). The size of exosomes is at nano-scale range and owing to their biocompatibility and other characteristics, they have been promising candidates for delivery of bioactive compounds and genetic materials in disease therapy, especially cancer therapy. Gastric cancer (GC) is a leading cause of death among patients and this malignant disease affects gastrointestinal tract that its invasiveness and abnormal migration mediate poor prognosis of patients. Metastasis is an increasing challenge in GC and microRNAs (miRNAs) are potential regulators of metastasis and related molecular pathways, especially epithelial-to-mesenchymal transition (EMT). In the present study, our aim was to explore role of exosomes in miR-200a delivery for suppressing EMT-mediated GC metastasis. Exosomes were isolated from MSCs via size exclusion chromatography. The synthetic miR-200a mimics were transfected into exosomes via electroporation. AGS cell line exposed to TGF-β for EMT induction and then, these cells cultured with miR-200a-loaded exosomes. The transwell assays performed to evaluate GC migration and expression levels of ZEB1, Snail1 and vimentin measured. Exosomes demonstrated loading efficiency of 5.92 ± 4.6%. The TGF-β treatment transformed AGS cells into fibroblast-like cells expressing two stemness markers, CD44 (45.28%) and CD133 (50.79%) and stimulated EMT. Exosomes induced a 14.89-fold increase in miR-200a expression in AGS cells. Mechanistically, miR-200a enhances E-cadherin levels (P < 0.01), while it decreases expression levels of β-catenin (P < 0.05), vimentin (P < 0.01), ZEB1 (P < 0.0001) and Snail1 (P < 0.01), leading to EMT inhibition in GC cells. This pre-clinical experiment introduces a new strategy for miR-200a delivery that is of importance for preventing migration and invasion of GC cells.