Abstract
In the tumor microenvironment, macrophages polarize into the M2 phenotype to facilitate tumorigenesis. Tumor-derived exosomes can act as mediators between the tumor microenvironment and stromal cells by transporting proteins, mRNAs, and miRNAs. Exosomal miRNAs play a pivotal role in modulating tumor microenvironment and macrophage polarization. Here, we overexpressed miR-130 and miR-33 in exosomes of MDA-MB-231 cells and investigated their effect on macrophage polarization and tumor progression. For this purpose, exosomes were extracted from MDA-MB-231 cells and characterized using dynamic light scattering, electron microscopy, and western blotting of exosomal markers. Then, miR-130 or miR-33 containing exosomes were used to treat IL4-induced M2 or tumor-associated macrophages (TAMs). After treatment, the polarization status of macrophages, including the expression of M1 specific genes, and the secretion of cytokines were evaluated. Finally, the conditioned medium from exosome-treated macrophages was incubated with cancer cells to evaluate its effect on the migration and invasion ability of cancer cells and, in vivo experiments investigated the effect of exosome-treated macrophages on breast cancer progression. Exosomes characterization results approved the range of size and homogeneity of extracted exosomes. Overexpression of miR-130 and miR-33 in exosomes increased the expression of M1 signature genes (IRF5, MCP1, CD80) and secretion of cytokines (IL-1β and TNF-α) as well as yeast phagocytic activity of macrophages. Besides, the conditioned medium of macrophages treated with miRNA containing exosomes declined the migration and invasion ability of cancer cells. The in vivo results indicated the inhibitory effect of exosome-treated macrophages on tumor growth. Furthermore, the results showed that in response to exosome-treated macrophages, the production of TNF-α by spleen cells increased, while the production of IL-10 and TGF-β by these cells decreased. These findings suggest that overexpression of miR-130 and miR-33 in exosomes can decrease tumor progression by shifting macrophage polarization from M2 to M1 phenotype and can be a potential therapeutic strategy for tumor interventions.