Background: Exosomes, emerging mediators of intercellular communication, are reported to transfer certain non-coding RNAs, such as microRNAs (miRNAs), which play a crucial role in cancer progression. The objective of this study was to determine the function of exosomal miR-126 and provide a novel mechanism of miR-126 action in NSCLC.
Methods: The morphology of exosomes was identified by transmission electron microscope (TEM), and the exosomal surface markers were quantified by western blot. The expression of miR-126 and integrin alpha-6 (ITGA6) mRNA was measured by quantitative real-time polymerase chain reaction (qRT-PCR), and ITGA6 protein expression was determined by western blot. For functional analyses, cell proliferation was assessed by colony formation assay and MTT assay. Cell cycle and cell apoptosis were monitored using flow cytometry assay. Cell migration and invasion were determined by transwell assay. ITGA6 was predicted as a target of miR-126 by bioinformatics analysis, which was verified by dual-luciferase reporter assay. The role of exosomal miR-126 in vivo was determined by Xenograft tumor models.
Results: NSCLC serum-derived exosomes harbored low expression of miR-126 and promoted NSCLC cell proliferation, cell cycle progression, cell migration and invasion. NSCLC serum-derived exosomes loaded with miR-126 mimic inhibits NSCLC cell proliferation, colony formation, migration and invasion but induced cell cycle arrest and apoptosis. Besides, exosomal miR-126 also blocked tumor growth in vivo. In mechanism, ITGA6 was a target of miR-126, and exosomal miR-126 weakened these NSCLC cell malignant behaviors and inhibited tumor growth by degrading the expression of ITGA6.
Conclusion: Exosomal miR-126 blocked the progression of NSCLC through the mediation of its target gene ITGA6, and exosomal miR-126 might be used as a promising biomarker for NSCLC therapy.
Keywords: Exosomes; ITGA6; NSCLC; miR-126.