The regulatory role of miR-182 in breast cancer malignancy and macrophage reprogramming is well-established. However, the mechanisms through which miR-182 overexpression in tumor cells influences macrophage polarization remain elusive.

Material and methods:
After transfection with miR-182-5p mimics, inhibitors, and controls for 24 hours, exosomes were extracted by differential centrifugation from transfected MDA-MB-231. Macrophages co-cultured with these exosomes to illustrate the regulative effects of exo-miR-182-5p reprogram macrophage. Furthermore, breast cancer cells co-cultured with exo-miR-182-5p reprogrammed M2 macrophages to demonstrate the effects of reprogrammed M2 macrophages to influence breast cancer progression. After all, these findings were validated in cell derived xenograft (CDX) BALB/C nude-mice model.

In this study, we demonstrate that exosome-derived miR-182-5p from TNBC cells reprograms M2 macrophage polarization through direct combined with Notch1, thereby enhancing breast cancer progression in vitro and in vivo. When co-cultured with exosomes from TNBC cells transfected with miR-182-5p mimics or inhibitors, macrophages showed altered Notch1/Hes1 pathway expression, leading to M2 polarization and subsequent changes in reactive oxygen species (ROS), inflammation, and other biochemical markers. Furthermore, breast cancer cells co-cultured with exosomes reprogrammed macrophages exhibited increased colony formation, migration, and invasion, as well as reduced apoptosis. These findings were validated in a BALB/C nude-mice model.

This study pioneers the elucidation of the feedback loop mechanism between breast cancer cells and macrophages mediated by the exosome-derived miR-182-5p/Notch1 pathway, highlighting its role in macrophage reprogramming. Although the therapeutic application of miR-182-5p inhibitors as anticancer agents remains in the early stages, targeting macrophage polarization represents a promising avenue for breast cancer therapy.

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