Effects of tumor-derived extracellular vesicles on T cell fate and function

Abstract

Abstract Immunosuppressive microenvironments created by malignant tumors represent a major obstacle for effective anti-tumor immunity. There are multiple immunosuppressive mechanisms operative in the tumor microenvironment (TME) that interfere with T cell function. Extracellular vesicle (EV) in tumor microenvironment is an important way employed by tumor cells to control T cell fate and function. However, the mechanisms responsible for EV-mediated T cell suppression and dysfunction are still largely unknown. Here, we purified EVs from human melanoma A375 and breast cancer MCF7 cell lines and then explored EV impacts on T cell function and fate in anti-tumor immunity. We found that tumor derived EVs can suppress T cell proliferation and induce T cell senescence, which is a novel and fundamentally important phenomenon that contributes to tumor-induced immunosuppression in the TME. Mechanistically, tumor derived EVs promoted DNA damage responses and cell cycle arrest of T cell that induces T cell senescence. Blockage of DNA damage signaling in T cells via the specific inhibitor KU55933 can prevent T cell senescence and recover T cell impaired effector functions. Importantly, we further performed in vivo studies to investigate that tumor-derived EVs can induce T cell suppression and senescence, which can also be reversed by specific signaling inhibitors or/and targeting signaling molecules via the CRISPR knockdown strategy. These studies facilitate a better understanding of the novel suppressive mechanism utilized by the TME and provide insights relevant to the development of effective strategies to reverse immune suppression for enhanced anti-tumor immunity. Supported by the grants from the Melanoma Research Alliance and National Institutes of Health.