Tumor extracellular vesicles (EVs), as endocytic vesicles able to transport
nucleic acids,
proteins, and metabolites in recipient cells, have been recognized fundamental mediators of cell-to-cell communication in
breast cancer. The biogenesis and release of EVs are highly regulated processes and both the quantity of EVs and their molecular cargo might reflect the metabolic state of the producing cells. We recently demonstrated that the
adipokine leptin, whose circulating levels correlate with adipose tissue expansion, is an inducer of EV release from
breast cancer cells. Here, we show a specific proteomic signature of EVs released by MCF-7
breast cancer cells grown in the presence of
leptin (Lep-EVs), in attempt to find additional molecular effectors linking
obesity to
breast cancer biology. An analysis of the proteomic profile of Lep-EVs by LC-MS/MS revealed a significant enrichment in biological processes, molecular functions, and cellular components mainly related to mitochondrial machineries and activity, compared to
protein content of EVs from untreated
breast cancer cells. Metabolic investigations, carried out to assess the autocrine effects of these vesicles on
breast cancer cells, revealed that Lep-EVs were able to increase
ATP levels in
breast cancer cells. This result is associated with increased mitochondrial respiration evaluated by Seahorse analyzer, supporting the concept that Lep-EVs can modulate MCF-7
breast cancer cell oxidative metabolism. Moreover, taking into account the relevance of
tumor immune cell crosstalk in the tumor microenvironment (TME), we analyzed the impact of these vesicles on macrophage polarization, the most abundant immune component in the breast TME. We found that
tumor-derived Lep-EVs sustain the polarization of M0 macrophages, derived from the human THP-1 monocytic cells, into M2-like tumor-associated macrophages, in terms of metabolic features, phagocytic activity, and increased expression of CD206-positive population. Overall, our results indicate that
leptin by inducing the release of EV-enriched in
mitochondrial proteins may control the metabolism of MCF-7
breast cancer cells as well as that of macrophages. Characterization of
tumor-derived EV
protein cargo in an
obesity-associated milieu, such as in the presence of elevated
leptin levels, might allow identifying unique features and specific metabolic mechanisms useful to develop novel therapeutic approaches for treatment of
breast cancer, especially in obese patients.