Exosome-mediated hepatocellular carcinoma progression by modulating macrophage metabolic reprogramming and macrophage M2 polarization via exosome-derived hsa_circ_0057320-miR-28-5p/E2F6 axis.
BACKGROUND Hepatocellular carcinoma is an aggressive malignancy with poor outcomes. Emerging studies highlight the importance of the tumor microenvironment in HCC progression, where exosomes serve as critical messengers linking tumor cells with surrounding stromal components. Although circRNAs are abundantly present in tumor-derived exosomes, their precise roles and mechanisms in HCC remain poorly defined. METHODS Exosomes were characterized using transmission electron microscopy and flow cytometry. Differentially expressed circRNAs were identified by RNA sequencing. Macrophage polarization and metabolic reprogramming were evaluated by western blotting, immunofluorescence and metabolomics. The role of hsa_circ_0057320, miR-28-5p, and E2F6 in HCC progression was examined through transwell, tube formation, and spheroid-sprouting assays. Xenograft mouse models were constructed to verify the role of them in metastasis and angiogenesis, exosomes in progression of HCC. Interactions among hsa_circ_0057320, miR-28-5p, and E2F6 were explored using RIP and dual-luciferase reporter assays. RESULTS In this study, we found that exosomes derived from HOXD3-treated HCCs induced macrophage polarization toward the M2 phenotype via metabolic reprogramming. In addition, HOXD3-stimulated HCC cells secreted exosomes enriched in hsa_circ_0057320, which induce the alternatively activated (M2) macrophage phenotype and enhanced angiogenesis and metastatic capability in vivo and vitro. The role of hsa_circ_0057320 in the metastasis and invasion of HCC was reversed after the enhance of miR-28-5p. E2F6, a target of miR-28-5p, was markedly upregulated in HCC tissues and cells. Additionally, a positive relationship was established between hsa_circ_0057320 and E2F6, contrasting with a negative association with miR-28-5p. CONCLUSIONS Exosomes derived from HOXD3-induced HCC cells promotes M2 macrophage polarization via metabolic reprogramming. In addition, HOXD3-induced exosomal hsa_circ_0057320 promotes macrophage M2 polarization via the miR-28-5p/E2F6 axis, thereby accelerating HCC malignancy. These findings reveal the interactive communication mechanism between HCCs and TME, and highlight hsa_circ_0057320 as a potential exosomal indicator and therapeutic target for metastatic HCC.