14-3-3ζ delivered by hepatocellular carcinoma-derived exosomes impaired anti-tumor function of tumor-infiltrating T lymphocytes

Abstract

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 14-3-3ζ expression was up-regulated in hepatocellular carcinoma (HCC) cells and in TILs. TILs with 14-3-3ζ high-expression (14-3-3ζhigh) exhibited impaired activation (CD69), proliferation (Ki67) and anti-tumor functions compared to 14-3-3ζ low expression (14-3-3ζlow) TILs. Flow cytometry assay showed that compared with 14-3-3ζlow CD8+T cells, 14-3-3ζhigh ones exhibited higher frequency of exhausted phenotypes as measured by inhibitory receptors such as PD-1, TIM-3, LAG3, and CTLA-4. 14-3-3ζ 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 14-3-3ζ 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 14-3-3ζ expression. Stochastic optical reconstruction microscopy (STORM) and confocal assay showed that 14-3-3ζ-containing exosomes derived from HCC cells could be swallowed by T cells, suggesting that 14-3-3ζ might be transmitted from HCC cells to TILs at least partially through exosomes. In conclusion, our study for the first time demonstrated that 14-3-3ζ is up-regulated in and inhibited the anti-tumor functions of tumor-infiltrating T cells in HCC microenvironment and that 14-3-3ζ might be transmitted from HCC cells to T cells at least partially through exosomes.

Circulating exosome‐derived bona fide long non‐coding RNAs predicting the occurrence and metastasis of hepatocellular carcinoma

“…10,11 It has been proved that ncRNA extracted from exosome could present a stable form to avoid the degradation induced by RNase, indicating they might be mediators for communications in different cells. 13 Various researches have proved that exosome-derived ncRNAs could act as markers for the diagnosis and prognosis prediction in various kinds of human cancers. 13 Various researches have proved that exosome-derived ncRNAs could act as markers for the diagnosis and prognosis prediction in various kinds of human cancers.…”

Extracellular vesicles, news about their role in immune cells: physiology, pathology and diseases

“…In this case, the EVs, mostly of tumour origin, play a role in the targeting of non-malignant or other cancer cells [56]. A mechanism of these EV effects is immune suppression of lymphocytes, such as CD8 + T, or macrophages [55][56][57][58][59], possibly dependent on the protein 14-3-3ζ over-expressed at the surface of the vesicles [60]. In addition to angiogenesis and metastasis [45][46][47], targeting occurs during cell migration and invasion [53,54].…”

“…Among biomarkers, some correspond to whole EVs, known to be released from particular cancer cells [45][46][47]; others are based on EV surface proteins, such as tetraspanins and 14-3-3ζ [3,60] or on miRNAs, such as miR-301a-3p and many others, abundant in the lumen of cancer EVs [46,48]. Important for these studies is the identification of biomarkers, useful for the strategy of medical action.…”

Exosome-based liquid biopsy in the management of hepatocellular carcinoma

“…However, depending on the starting material and downstream applications, other methods for the purification and enrichment of HCC-derived exosomes have also been used such as ultrafiltration, size exclusion chromatography (SEC) or the ExoQuick TC method [19,29] . Majority of HCC-derived exosomes have been identified by a combination of different methods including, round or cup shaped morphology by transmission electron microscopy, size of 50-100 nm in diameter by nanoparticle tracking analysis and exosomal surface profiling for markers such the tetraspanins (CD9, CD63, and CD81), heat shock proteins (HSP90 and HSP60), Alix and Tsg101 by immunoblot and flow cytometry [19,20,[29][30][31][32] . Studies have demonstrated high expression of glypican-3 (GPC-3) and AFP, traditional markers of HCC, within the HCC-derived exosomes, thereby confirming the hepatoma-based origin of these exosomes [31] .…”

“…For instance, Wang et al [32] demonstrated that 14-3-3ζ, also called 14-3-3 protein zeta was transmitted from HCC cells to T cells via exosomes and resulted in the inhibition of anti-tumour functions of tumour-infiltrating T cells in the HCC microenvironment. HCC-derived exosomes have been shown to be enriched in HCC antigens, which in turn can prime cytotoxic T lymphocytes and elicit a stronger immune response in vitro and in vivo compared with cell lysates [4] .…”