Exosomes derived from itaconate-treated macrophages promote epithelial-mesenchymal transition, migration, and invasion in MCF-7 breast cancer cells.

Itaconic acid is an immunometabolite that regulates macrophage polarization within the tumor microenvironment and influences tumor progression and invasion. Although its anti-cancer and tumor-promoting effects remain controversial, its role in modulating macrophage-derived exosomes and their impact on breast cancer cells is not well understood. This study investigated the effects of exosomes derived from dimethyl itaconate (DMI)-treated macrophages on epithelial-mesenchymal transition (EMT), apoptosis, migration, and EMT-related miRNAs in MCF7 breast cancer cells. U937 macrophages were treated with 250 µM DMI for 48 h. Exosomes (DMI-EXO) were subsequently isolated, characterized, and used to treat MCF7 cells. The expression of EMT-related proteins (E-cadherin, N-cadherin, ZEB1/2, Slug, and Vimentin) and EMT-associated miRNAs (miR200C-5p, miR30C-5p, miR-638, and miR-137) was evaluated by Western blotting and quantitative real-time PCR, respectively. Apoptosis, cell migration, and invasion were assessed using Annexin V/PI staining, the scratch wound-healing assay, and the Transwell invasion assay, respectively. DMI-EXO treatment significantly increased the expression of the mesenchymal markers N-cadherin, ZEB1/2, Slug, and Vimentin while reducing the epithelial marker E-cadherin. In addition, the expression of EMT-suppressive miRNAs, including miR200C-5p and miR30C-5p, was significantly decreased, whereas no significant change was observed in miR-137 expression following DMI-EXO treatment. DMI-EXO treatment did not significantly alter apoptosis in MCF-7 cells but enhanced cell migration and invasion, as demonstrated by accelerated wound closure in the scratch assay and increased invaded area in the Transwell invasion assay. These findings indicate that DMI-induced macrophage-derived exosomes promote EMT and migration in breast cancer cells by modulating EMT-related proteins and miRNAs. This study provides new evidence that itaconic acid may facilitate breast tumor progression through exosome-mediated communication between macrophages and cancer cells.