Ferroptosis-dependent extracellular vesicles from macrophage contribute to asbestos-induced mesothelial carcinogenesis through loading ferritin.

Asbestos-associated diseases remain a social burden worldwide. Our previous studies identified asbestos-induced iron-rich milieu for mesothelial cells with ceaseless macrophage ferroptosis. However, molecular mechanisms how this mutagenic milieu influences mesothelial cells have not been elucidated yet. Here, we propose a novel mechanism that extracellular vesicles (EVs) mediate asbestos-associated mutagenic factors to mesothelial cells. In a mice model of intraperitoneal crocidolite injection, mutagenic milieu highly expressed CD63, an exosomal marker. We then used a GFP-CD63 labeled THP-1 macrophage model exposed to crocidolite/iron, which generated EVs under ferroptotic process. We observed that MeT-5A mesothelial cells can receive and internalize these EVs. Furthermore, we comprehensively analyzed the ferroptosis-dependent EVs (FedEVs) for transported proteins and identified ferritin heavy/light chains as major components. Therefore, we inferred that FedEVs transport iron from ferroptotic macrophages to mesothelial cells. RNA sequencing revealed that the mesothelial cells receiving higher amounts of the FedEVs were mitotic, especially at the S and G2/M phases, by the use of Fucci mesothelial cells. Nuclear 8-hydroxy-2'-deoxyguanosine and γ-H2AX were significantly increased in the recipient mesothelial cells after exposure to FedEVs. Collectively, we here demonstrate a novel mechanism that FedEVs act as a key mutagenic mediator by transporting iron, which contribute to asbestos-induced mesothelial carcinogenesis.