Abstract P5-12-07: Proteomic profiling of extracellular vesicles released from leptin-treated breast cancer cells: A potential role in cancer metabolism

Abstract

Abstract Extracellular vesicles (EVs), nanosized particles enclosed within a phospholipid bilayer membrane, are recognized key determinants of cell-to-cell communication in breast cancer, able to modulate phenotypic behavior of recipient cells by transferring their molecular cargo. Recently, we identified the adipokine leptin, whose circulating levels are elevated in obesity, as an important regulator of EV biogenesis and release in mammary carcinoma cells. Here, we focused on the identification of a specific leptin-induced EV proteomic signature in attempt to find molecular effectors associated with breast cancer progression. To this end, we analyzed protein content of EVs, isolated by ultracentrifugation method from conditioned media of ER-α positive MCF-7 breast cancer cells grown in the presence of leptin. EVs were fully characterized using Transmission Electron Microscopy (TEM), Nanoparticle Tracking Analysis (NTA) and Immunoblotting. Proteomic analysis of EV cargo, obtained by liquid chromatography-tandem mass spectrometry analysis (LC-MS/MS), revealed an altered protein profile, identifying 274 up-regulated proteins (FC>1.5) in EVs from leptin-treated cells compared to EV from untreated ones. Gene set enrichment analysis (GSEA) was used to explore Gene Ontology categories enriched in the entire list of up-regulated proteins. We identified a number of significantly enriched biologic processes mainly involved in energy production and mitochondrial metabolism, including “generation of precursor metabolites and energy” (GO:0006091), “fatty acid metabolic process” (GO:0006631), “mitochondrial respiratory chain” (GO:0033108), “mitochondrial gene expression” (GO:0140053) and “mitochondrial transport” (GO:0006839). Expression of up-regulated proteins, in both cell and EV lysates, was validated by immunoblotting. Protein-protein interaction network analysis revealed CYC1 (Cytochrome c-1), NDUFV2 (NADH:ubiquinone oxidoreductase core subunit V2), and NDUFAB1 (NADH:ubiquinone oxidoreductase subunit AB1), important subunits of mitochondrial complexes and enhancer of mitochondrial metabolism, as the most interactive proteins among that up-regulated in EVs released by leptin-treated breast cancer cells. This suggests a role for leptin-treated EVs in enhancing oxidative phosphorylation in both epithelial breast cancer cells and their surrounding microenvironment. Collectively, our data indicate that the adipokine leptin could induce in breast cancer cells the release of EVs enriched in specific proteins mainly involved in mitochondrial metabolism. Since, mitochondrial function is essential for supplying energy to support breast cancer cell growth and progression, understanding the metabolic mechanisms mediated by EV released by breast cancer cells may provide important clues to develop novel therapeutic approaches for treatment of breast cancer especially in obesity setting. Citation Format: Luca Gelsomino, Giusi La Camera, Ines Barone, Salvatore Panza, Giovanna Morello, Amanda Caruso, Chiara Chiodo, Daniela Bonofiglio, Cinzia Giordano, Sebastiano Andò, Stefania Catalano. Proteomic profiling of extracellular vesicles released from leptin-treated breast cancer cells: A potential role in cancer metabolism [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-12-07.