Molecular Profiling and Functional Analysis of Macrophage-Derived Tumor Extracellular Vesicles

Abstract

Summary: Extracellular vesicles (EVs), including exosomes, modulate multiple aspects of cancer biology. Tumor-associated macrophages (TAMs) secrete EVs, but their molecular features and functions are poorly characterized. Here, we report methodology for the enrichment, quantification, and proteomic and lipidomic analysis of EVs released from mouse TAMs (TAM-EVs). Compared to source TAMs, TAM-EVs present molecular profiles associated with a Th1/M1 polarization signature, enhanced inflammation and immune response, and a more favorable patient prognosis. Accordingly, enriched TAM-EV preparations promote T cell proliferation and activation ex vivo. TAM-EVs also contain bioactive lipids and biosynthetic enzymes, which may alter pro-inflammatory signaling in the cancer cells. Thus, whereas TAMs are largely immunosuppressive, their EVs may have the potential to stimulate, rather than limit, anti-tumor immunity. : Cianciaruso et al. develop methods for the analysis of extracellular vesicles secreted by macrophages in mouse tumors (TAM-EVs). Proteomic and lipidomic profiling indicates that TAM-EVs carry modulators of inflammation and lipid metabolism that could influence the properties of the tumor immune microenvironment. Keywords: extracellular vesicle, exosome, tumor microenvironment, tumor-associated macrophage, proteomics, lipidomics, lipid metabolism, inflammation, T cell response