MiR-124-3p impedes the metastasis of non-small cell lung cancer via extracellular exosome transport and intracellular PI3K/AKT signaling

Abstract

Background: Metastasis is a significant factor that affects the survival of patients with non-small cell lung cancer (NSCLC). Nevertheless, the molecular regulatory mechanism underlying the metastasis is currently not fully understood. This study aims to identify the important role of miR-124-3p in metastasis of NSCLC, thereby providing a potential therapeutic intervention. Methods: Exosome secretion was determined by Nanoparticle Tracking Analysis (NTA) and the uptake was measured by fluorescence inverted microscope. The binding mechanism between miR-124-3p and its upstream or downstream target genes was validated experimentally by Luciferase reporter. Cells migration was evaluated by transwell assays. Transcriptome sequencing on A549 was carried out to verify the potential signaling pathway underlying miR-124-3p regulation. Western blotting analysis was used to assess the level of AKT, p-AKT, PI3K, and p-PI3K protein expression in NSCLC cell lines. The role of miR-124-3p to suppress the tumor metastasis was verified in NSCLC xenograft model. Results: Exosomes were more abundant in serum from patients with advanced lung cancer (n = 24 patients) than in these from patients with early-stage lung cancer (n = 30 patients), which suggested the potential correlation between amount of exosome secretion and the metastasis of NSCLC. Interestingly, the exosome release, uptake and the migration of NSCLC cells were notably inhibited by miR-124-3p. LINC00511 suppressed the expression of miR-124-3p to facilitate exosome transport due to its role as the competitive endogenous RNA for miR-124-3p. The miR-124-3p could directly target the 3′-UTR of Rab27a in NSCLC cells to inhibit exosome secretion and thereby prevent cell migration and invasion. Aside from the inhibition of exosome transport, miR-124-3p inhibited the activation of PI3K/AKT signaling in the intracellular environment. Finally, by measuring subcutaneous tumor weight and volume and lung metastasis, we also demonstrated that miR-124-3p inhibited tumor growth in vivo. Conclusion: In NSCLC, miR-124-3p significantly suppressed metastasis through extracellular exosome transport and intracellular PI3K/AKT signaling. These findings provide new insights toward a better understanding of the NSCLC metastasis and suggest a potential treatment biomarker for NSCLC.