14-3-3? Delivered By Hepatocellular Carcinoma-derived Exosomes Impaired Anti-tumor Function Of Tumor-infiltrating T Lymphocytes

Increasing evidence shows that the anti-tumor functions of tumor-infiltrating T lymphocytes?TILs?were inhibited significantly,but the underlying mechanisms remain not fully understood.In this study,we found that 14-3-3?expression was up-regulated in hepatocellular carcinoma?HCC?cells and in TILs.TILs with 14-3-3?high-expression(14-3-3?^high)exhibited impaired activation?CD69?,proliferation?Ki67?and anti-tumor functions compared to 14-3-3?low expression(14-3-3?^low)TILs.Flow cytometry assay showed that compared with 14-3-3?^low CD8⁺T cells,14-3-3?^high ones exhibited higher frequency of exhausted phenotypes as measured by inhibitory receptors such as PD-1,TIM-3,LAG3,and CTLA-4.14-3-3?overexpression inhibited the activity and proliferation of peripheral blood CD3⁺T cells,deviated the differentiation of naive T cells from effector T cells to regulatory T cells.Moreover,we found that 14-3-3?expression levels in TILs correlated positively with those in HCC cells.Naive T cells co-cultured with HCC cells or the visible components of culture medium of HCC cells exhibited increased 14-3-3?expression.Stochastic optical reconstruction microscopy?STORM?and confocal assay showed that14-3-3?-containing exosomes derived from HCC cells could be swallowed by T cells,suggesting that 14-3-3?might be transmitted from HCC cells to TILs at least partially through exosomes.In conclusion,our study for the first time demonstrated that 14-3-3?is up-regulated in and inhibited the anti-tumor functions of tumor-infiltrating T cells in HCC microenvironment and that 14-3-3?might be transmitted from HCC cells to T cells at least partially through exosomes.For the first time,we have elucidated the function of 14-3-3?in T cells and the potential mechanism of up-regulation of the expression of 14-3-3?in TILs.Our research provides a new perspective for exploring T cell dysfunction in patients with hepatocellular carcinoma and opens a new way for the development of a new immunotherapy target for liver cancer.