RÉSUMÉ
Exosomes are involved in invasion, migration and angiogenesis of tumor cells, and invasion is the main cause of death in glioma patients. Studies have shown that the exosomes secreted by tumor cells can carry miRNA into the receptor cells and regulate the biological functions of the receptor cells, such as proliferation, migration and invasion. miR-574-5p plays a key role in the occurrence and development of a variety of tumors. However, whether the exosomes derived from glioma cells express miR-574-5p and its role in the growth, invasion and migration of glioma cells have not been reported. This study investigated the mechanism of the exosomal miR-574-5p secreted from glioma cells in the process of cell proliferation, migration and invasion. The exosomes were characterized by electron microscopy, nanoparticle size tracking and Western blot. The results displayed that the extracted exosomes were round particles with a diameter of 30 ~ 100 nm. The internalization of exosomes was detected by immunofluorescence assay. The results showed that exosomes were internalized into LN229 cells; Bioinformatics and online data were used to screen the differentially secreted miRNA between LN229 and H4 glioma cells. The results showed that the differentially secreted miRNA was miR-574-5p, and large tumor suppressor 2 (LATS2) was predicted to be the target gene of miR-574-5p; Duel luciferase reporter assay confirmed that miR-574-5p was complementary to the 3'UTR region of LATS2; The transfection assay, qRT-PCR and Western blot was conducted to measure the relationship between miR-574-5p and LATS2. The results demonstrated that there was no significant difference in LATS2 mRNA levels between the control group and the group with miR-574-5P overexpression (P > 0.05), suggesting the regulatory effect of miR-574-5P on LATS2 was achieved by inhibiting its translation (P < 0.05). CCK-8, Transwell migration and invasion assays were conducted to explore the effect of miR-574-5p on proliferation, migration and invasion of LN229 cells. The results showed that overexpression of miR-574-5p could significantly promote the ability of proliferation, migration and invasion of LN229 cells (P < 0.05). In addition, Western blot was performed to measure the expression of kinase proteins involved in the LATS2/YAP signaling pathway, and the influence of the exosomes on this signaling pathway. The results revealed that the exosomes down-regulated the protein expression level of LATS2 and reduced p-YAP phosphorylation. In conclusion, the exosomal miR-574-5p can promote the proliferation, migration and invasion of glioma cells by down-regulating LATS2 and activating LATS2/YAP signaling pathway, which may provide a potential biomarker for the diagnosis and target for the treatment of glioma.