Mesothelial cell-derived EVs promote angiogenesis by transferring Angiopoietin-2, activating PI3K/Akt/ERK1/2 pathways.

Peritoneal metastasis is a critical factor in the progression and recurrence of epithelial ovarian cancer (EOC) and advanced gastrointestinal cancers, significantly remodeling the peritoneal tumor microenvironment (TME). Current treatments often fall short due to the complex interplay between tumor and stromal cells, which fosters a pre-metastatic niche. While tumor-derived extracellular vesicles (EVs) are well-studied in cancer progression, the specific role of mesothelial cells-derived EVs in regulating angiogenesis and endothelial function, a key process for tumor growth and metastasis, remains largely unexplored.

Extracellular vesicles (EVs) were isolated from conditioned media of mesothelial cells and thoroughly characterized. Researchers then assessed their impact on endothelial cell behavior using a battery of functional assays, including proliferation, migration, and invasion assays. They also employed Matrigel-based tube formation assays in vitro and in vivo angiogenesis plug models to evaluate angiogenesis. A proteome profiler angiogenesis array was utilized to pinpoint pro-angiogenic mediators within the EVs. Mechanistic studies, including lentiviral knockdown and overexpression strategies, were performed to elucidate specific signaling pathways.

Endothelial cells readily internalized mesothelial cells-derived EVs, leading to significant increases across multiple angiogenic parameters. In vitro, these EVs boosted endothelial cell proliferation, migration, and invasion. Furthermore, they significantly enhanced angiogenesis in both Matrigel-based tube formation assays and in vivo angiogenesis plug models. Proteomic profiling of the mesothelial cell-derived EVs identified 43 distinct angiogenic regulators. >Angiopoietin-2 (ANG2) emerged as a key effector, demonstrating a central role in the observed pro-angiogenic effects. Mechanistic studies confirmed that mesothelial cells-derived EVs-induced angiogenesis was primarily mediated through the ANG2-TIE2 signaling pathway. This activation subsequently led to the downstream activation of PI3K, Akt, and ERK1/2 pathways. Crucially, experimental inhibition of ANG2 markedly reduced these observed angiogenic effects, underscoring its pivotal role.