Ovarian Cancer Cell-Derived Exosomal miR-205 Promotes M2 Macrophage Polarization and Ovarian Cancer Cell Metastasis By Activating The AKT/mTOR Signalling Pathway

Background: Tumour-associated macrophages (TAMs) are the most abundant immune cells in the tumour environment and are considered to be similar to M2 macrophages, which facilitate cancer progression. Exosomes, as important mediators of cell-to-cell communication, can alter the phenotype of TAMs by transferring microRNAs (miRNAs) that influence targets and signalling pathways. However, the exact mechanisms by which cancer-derived exosomal miRNAs facilitate the development and metastasis of ovarian cancer (OC) remain unclear. Methods: : In situ hybridization and immunohistochemistry were performed to examine the relationship between miR-205 and CD163 in OC. Exosome labelling experiments and qRT-PCR were used to detect the transfer of miR-205 from OC cells to macrophages. The effects of exosomal miR-205-induced macrophages on OC cell migration, invasion and EMT were assessed by in vitro assays in a co-culture model. Western blotting and qRT-PCR experiments were performed to investigate the role of the PI3K/AKT/mTOR axis in M2 macrophage polarization induced by exosomal miR-205. An in vivo mouse tumour model was used to evaluate the effects of M2 macrophages induced by exosomal miR-205. Results: : We found that miR-205 expression levels were associated with M2 macrophage infiltration in patients with OC. miR-205 could be transported from OC cells to macrophages via exosomes and altered the macrophage phenotype. Moreover, macrophages that received exosomal miR-205 further enhanced the invasion, migration and EMT of OC cells. Decreased PTEN levels caused by exosomal miR-205 could increase the activation of AKT and mTOR as well as the expression of several immunosuppressive factors. In contrast, inhibition of miR-205 or restoration of PTEN effectively decreased cancer-mediated M2-type polarization, improving the infiltration of inflammatory factors in the tumour environment. Exosomal miR-205 derived from OC cells was found to induce M2-type polarization of macrophages and promote cancer progression in vivo. Conclusions: : These results suggest a novel mechanism by which exosomal miR-205 induces M2 macrophage polarization and facilitates OC progression by targeting the PI3K/AKT/mTOR axis. Targeting exosomal miR-205 may offer a potential diagnosis and treatment strategy for OC.