Aim
Exosomal miRNAs derived from glioblastoma stem cells (GSCs) are important mediators of immunosuppressive microenvironment formation in glioblastoma multiform (GBM), especially in M2-like polarization of tumor-associated macrophages (TAMs). However, the exact mechanisms by which GSCs-derived exosomes (GSCs-exo) facilitate the remodeling of the immunosuppressive microenvironment of GBM have not been elucidated.
Conclusion
GSCs secrete miR-6733-5p-rich exosomes to induce M2-like polarization of macrophages, as well as enhance GSCs stemness and promote malignant behaviors of GBM through IGF2BP3 activated AKT pathway. Targeting GSCs exosomal miR-6733-5p may provide a potential new strategy against GBM.
Methods
Transmission electron microscopy (TME) and nanoparticle tracking analysis (NTA) were applied to verify the existence of GSCs-derived exosomes. Sphere formation assays, flow cytometry, and tumor xenograft transplantation assays were performed to identify the exact roles of exosomal miR-6733-5p. Then, the mechanisms of miR-6733-5p and its downstream target gene regulating crosstalk between GSCs cells and M2 macrophages were further investigated.
Results
GSCs-derived exosomal miR-6733-5p induce macrophage M2 polarization of TAMs by positively targeting IGF2BP3 to activate the AKT signaling pathway, which further facilitates the self-renewal and stemness of GSCs.