MDA-MB-231-derived extracellular vesicles induce a distinct phenotypic and functional state in human monocytes

The tumor microenvironment (TME) is a critical driver of cancer progression, in which monocytes contribute to tumor development through their phenotypic and functional plasticity. Tumor-derived extracellular vesicles (EVs) are key mediators of intercellular communication within the TME, particularly shaping the immune landscape. Herein, we investigated the effects of MDA-MB-231-derived EVs (MDA-EVs) on the phenotype, molecular profile, and function of human monocytes. MDA-EVs induced a marked expansion of the classical CD14 + + CD16⁻ monocyte subset, accompanied by a reduction in intermediate and non-classical subsets. MDA-EVs also increased CX3CR1 expression across monocyte subsets in a TLR4-dependent manner, while reducing CCR2 expression in classical monocytes, suggesting a shift in migratory signaling. Monocytes exposed to MDA-EVs increased CD206 and arginase-1 expression, HO-1 and TNF-α mRNA levels, and enhanced monocyte migration and invasion. These changes were accompanied by reduced PKM2 Tyr105 phosphorylation, NF-κB activity, and intracellular reactive oxygen species (ROS) levels. Importantly, EV-educated monocytes enhanced the migratory capacity of MDA-MB-231 cells, indicating a tumor-supportive functional effect. Together, these changes support the acquisition of a distinct activation state.