Klibi, J. et al. Blood diffusion and Th1-suppressive effects of galectin-9-containing exosomes released by Epstein-Barr virus-infected nasopharyngeal carcinoma cells. Blood 113, 1957-1966

Université Paris-Sud, Centre National de la Recherche Scientifique-Unité Mixte de Recherche 8126, Paris, France.
Blood (Impact Factor: 10.45). 12/2008; 113(9):1957-66. DOI: 10.1182/blood-2008-02-142596
Source: PubMed


Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC) is the third most frequent virus-associated human malignancy. How this tumor escapes immune recognition despite the expression of several viral antigens has remained poorly understood. Our previous in vitro studies have shown that NPC cells release exosomes containing high amounts of galectin-9, a ligand of the membrane receptor Tim-3, which is able to induce apoptosis in mature Th1 lymphocytes. Here, we sought to determine whether galectin-9-carrying exosomes were produced in NPC patients and whether such exosomes might play a role in the immune evasion of NPC cells. We report that galectin-9-containing exosomes are selectively detected in plasma samples from NPC patients and mice xenografted with NPC tumors. The incorporation into exosomes protects galectin-9 against proteolytic cleavage but retains its Tim-3-binding capacity. Importantly, NPC exosomes induce massive apoptosis in EBV-specific CD4(+) cells used as a model of target T cells. This effect is inhibited by both anti-Tim-3 and antigalectin-9 blocking antibodies. These results indicate that blocking galectin-9/Tim-3 interaction in vivo might alleviate the Th1-suppressive effect of NPC exosomes and sustain antitumoral T-cell responses and thereby improve clinical efficacy of immunotherapeutic approaches against NPC.

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    • "This could promote tumor metastasis especially if loss of galectin-9 in tumor cells results in loss of tissue integrity [45]. Finally, it has been reported that in animal models and cancer patients, tumor cells can release galectin-9 containing exosomes that can induce T-cell apoptosis [48], [49]. Whether tumor endothelial cells also secrete galectin-9 containing exosomes needs to be further investigated, but such a mechanism could contribute to tumor progression by providing a way to escape immune surveillance. "
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    ABSTRACT: Approximately 30-40% of the patients with early stage non-small cell lung cancer (NSCLC) will present with recurrent disease within two years of resection. Here, we performed extensive galectin expression profiling in a retrospective study using frozen and paraffin embedded tumor tissues from 87 stage I/II NSCLC patients. Our data show that galectin mRNA expression in NSCLC is confined to galectin-1, -3, -4, -7, -8, and -9. Next to stage, univariable Cox regression analysis identified galectin-1, galectin-9FL and galectin-9Δ5 as possible prognostic markers. Kaplan-Meier survival estimates revealed that overall survival was significantly shorter in patients that express galectin-1 above median levels, i.e., 23.0 (2.9-43.1) vs. 59.9 (47.7-72.1) months (p = 0.020) as well as in patients that express galectin-9Δ5 or galectin-9FL below the median, resp. 59.9 (41.9-75.9) vs. 32.8 (8.7-56.9) months (p = 0.014) or 23.2 (-0.4-46.8) vs. 58.9 (42.9-74.9) months (p = 0.042). All three galectins were also prognostic for disease free survival. Multivariable Cox regression analysis showed that for OS, the most significant prognostic model included stage, age, gal-1 and gal-9Δ5 while the model for DFS included stage, age and gal-9Δ5. In conclusion, the current study confirms the prognostic value of galectin-1 and identifies galectin-9Δ5 as novel potential prognostic markers in early stage NSCLC. These findings could help to identify early stage NSCLC patients that might benefit most from adjuvant chemotherapy.
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    • "The presence of a Gly-Ala repeat domain in its sequence allows EBNA1 to escape the recognition of CD8 T-cells by preventing it from proteasomal degradation and presentation to major histocompatibility complex (MHC) class I.102–104 The detection of BARF1- and LMP1-containing exosomes in the circulation of NPC cases indicates that EBV continuously intervenes with the immune system during malignant development. Secreted exosomes have been observed to associate with LMP1 to silence local T-cells or cell regulatory molecules such as galectin-9.69,70,105,106 In addition, exosomes carry viral miRNAs that can modulate host immune cells.68 "
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    ABSTRACT: Nasopharyngeal carcinoma (NPC) is highly endemic in certain regions including the People's Republic of China and Southeast Asia. Its etiology is unique and multifactorial, involving genetic background, epigenetic, and environment factors, including Epstein-Barr virus (EBV) infection. The presence of EBV in all tumor cells, aberrant pattern of antibodies against EBV antigens in patient sera, and elevated viral DNA in patient circulation as well as nasopharyngeal site underline the role of EBV during NPC development. In NPC tumors, EBV expresses latency type II, where three EBV-encoded proteins, Epstein-Barr nuclear antigen 1, latent membrane protein 1 and 2 (LMP1, 2), are expressed along with BamH1-A rightward reading frame 1, Epstein-Barr virus-encoded small nuclear RNAs, and BamH1-A rightward transcripts. Among all encoded proteins, LMP1 plays a central role in the propagation of NPC. Standard treatment of NPC consists of radiotherapy with or without chemotherapy for early stage, concurrent chemoradiotherapy in locally advanced tumors, and palliative systemic chemotherapy in metastatic disease. However, this standard care has limitations, allowing recurrences and disease progression in a certain proportion of cases. Although the pathophysiological link and molecular process of EBV-induced oncogenesis are not fully understood, therapeutic approaches targeting the virus may increase the cure rate and add clinical benefit. The promising results of early phase clinical trials on EBV-specific immunotherapy, epigenetic therapy, and treatment with viral lytic induction offer new options for treating NPC.
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