M2 macrophage-secreted exosomes promote metastasis and increase vascular permeability in hepatocellular carcinoma

Abstract

Background: Metastasis is a key feature of malignant tumors and significantly contributes to their high mortality, particularly in hepatocellular carcinoma (HCC). Therefore, it is imperative to explore the mechanism of tumor metastasis. Recently, tumor-associated macrophages (TAMs) have been demonstrated to promote tumor progression, while TAM-derived molecules involved in HCC metastasis warrant further investigation. Methods: THP-1 was treated with IL-4 (Interleukin-4) and IL-13 (Interleukin-13) for M2 polarized macrophages. Exosomes derived from M2 macrophages were characterized. Then, HCC cells or human umbilical vein endothelial cells (HUVECs) were co-cultured with M2 macrophages or treated with M2 macrophage-secreted exosomes. Next, Transwell®, Scratch assay, tube formation, and endothelial permeability assays were performed. Moreover, RT-PCR, western blotting, immunofluorescence, and ELISA were used to assess mRNA and protein expression levels. Finally, the miRNA expression profiles of exosomes derived from M2 and M0 macrophages were analyzed. Results: M2 macrophage infiltration was correlated with metastasis and a poor prognosis in HCC patients. M2-derived exosomes were absorbed by HCC and HUVEC cells and promoted the epithelial-mesenchymal transition (EMT), vascular permeability, and angiogenesis. Notably, MiR-23a-3p levels were significantly higher in M2-derived exosomes and hnRNPA1 mediated miR-23a-3p packaging into exosomes. Phosphatase and tensin homolog (PTEN) and tight junction protein 1 (TJP1) were the targets of miR-23a-3p, as confirmed by luciferase reporter assays. Lastly, HCC cells co-cultured with M2-derived exosomes secreted more GM-CSF, VEGF, G-CSF, MCP-1, and IL-4, which in turn further recruited M2 macrophages. Conclusions: Our findings suggest that M2 macrophage-derived miR-23a-3p enhances HCC metastasis by promoting EMT and angiogenesis, as well as increasing vascular permeability. [MediaObject not available: see fulltext.]