Secreted phospholipase A<sub>2</sub> modifies extracellular vesicles and accelerates B cell lymphoma.

Kudo, Kai; Miki, Yoshimi; Carreras, Joaquim; Nakayama, Shunya; Nakamoto, Yasushi; Ito, Masatoshi; Nagashima, Etsuko; Yamamoto, Kei et al. · Cell Metab · 2022

basic_science · Level V

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Abstract

Extracellular vesicles (EVs) including exosomes act as intercellular communicators by transferring protein and microRNA cargoes, yet the role of EV lipids remains unclear. Here, we show that the pro-tumorigenic action of lymphoma-derived EVs is augmented via secreted phospholipase A<sub>2</sub> (sPLA<sub>2</sub>)-driven lipid metabolism. Hydrolysis of EV phospholipids by group X sPLA<sub>2</sub>, which was induced in macrophages of Epstein-Barr virus (EBV) lymphoma, increased the production of fatty acids, lysophospholipids, and their metabolites. sPLA<sub>2</sub>-treated EVs were smaller and self-aggregated, showed better uptake, and increased cytokine expression and lipid mediator signaling in tumor-associated macrophages. Pharmacological inhibition of endogenous sPLA<sub>2</sub> suppressed lymphoma growth in EBV-infected humanized mice, while treatment with sPLA<sub>2</sub>-modified EVs reversed this phenotype. Furthermore, sPLA<sub>2</sub> expression in human large B cell lymphomas inversely correlated with patient survival. Overall, the sPLA<sub>2</sub>-mediated EV modification promotes tumor development, highlighting a non-canonical mechanistic action of EVs as an extracellular hydrolytic platform of sPLA<sub>2</sub>.

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