Epstein-Barr Virus-Induced VEGF and GM-CSF Drive Nasopharyngeal Carcinoma Metastasis via Recruitment and Activation of Macrophages

Distinct Changes of BTLA and HVEM Expressions in Circulating CD4+ and CD8+ T Cells in Hepatocellular Carcinoma Patients

BTLA/HVEM (B and T lymphocyte attenuator/herpes virus entry mediator) pathways play a critical role in T cell suppression in tumor. However, its dynamic changes in different T cell subsets in peripheral blood and their clinical significance are largely unclear in cancer patients. In the current study, we showed distinct changes of BTLA and HVEM expressions on peripheral blood CD4⁺ and CD8⁺ T cells in patients with hepatocellular carcinoma (HCC); BTLA expression were significantly upregulated on circulating CD4⁺ but not CD8⁺ T cells. In sharp contrast, the levels of HVEM expression were significantly downregulated on circulating CD8⁺ but not CD4⁺ T cells. A strong positive correlation between BTLA expression on circulating CD4⁺ T cells and BTLA expression on autologous CD8⁺ counterparts was observed in healthy donors but absent in HCC patients. More importantly, we found that blockade of the BTLA/HVEM pathway increased IFN-γ production in both circulating CD4⁺ and CD8⁺ T cells. Collectively, our data suggested that the BTLA/HVEM pathway contributes to peripheral T cell suppression in HCC patients, and BTLA/HVEM may serve as attractive targets for HCC immunotherapy.

Induction of chemokine (C-C motif) ligand 5 by Epstein-Barr virus infection enhances tumor angiogenesis in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is etiologically associated with Epstein–Barr virus (EBV) infection and is known to be highly vascularized. Previous studies have suggested that EBV oncoproteins contribute to NPC angiogenesis. However, the regulatory network of EBV in angiogenesis still remains elusive. Herein, we reveal a novel mechanism of EBV‐induced angiogenesis in NPC. First, we showed that EBV‐infected NPC cell lines generated larger tumors with more microvessels in mouse xenograft models. Subsequent proteomic analysis revealed that EBV infection increased the expression of a series of angiogenic factors, including chemokine (C‐C motif) ligand 5 (CCL5). We then proved that CCL5 was a target of EBV in inducing tumor angiogenesis and growth. Further investigation through transcriptome analysis indicated that the pro‐angiogenic function of CCL5 might be mediated by the PI3K/AKT pathway. Furthermore, we confirmed that activation of the PI3K/AKT and hypoxia‐inducible factor‐1α pathways was essential for CCL5‐promoted angiogenesis. Finally, the immunohistochemical analysis of human NPC specimens also showed that CCL5 was correlated with angiogenesis. Taken together, our study identifies CCL5 as a key EBV‐regulated molecular driver that promotes NPC angiogenesis, suggesting it as a potential therapeutic target.

Interplay of Viral Infection, Host Cell Factors and Tumor Microenvironment in the Pathogenesis of Nasopharyngeal Carcinoma

Undifferentiated nasopharyngeal carcinoma (NPC) is strongly associated with Epstein-Barr virus (EBV) infection. In addition, heavy infiltration of leukocytes is a common characteristic of EBV-associated NPC. It has long been suggested that substantial and interactive impacts between cancer and stromal cells create a tumor microenvironment (TME) to promote tumorigenesis. The coexistence of tumor-infiltrating lymphocytes with EBV-infected NPC cells represents a distinct TME which supports immune evasion and cancer development from the early phase of EBV infection. Intracellularly, EBV-encoded viral products alter host cell signaling to facilitate tumor development and progression. Intercellularly, EBV-infected cancer cells communicate with stromal cells through secretion of cytokines and chemokines, or via release of tumor exosomes, to repress immune surveillance and enhance metastasis. Although high expression of miR-BARTs has been detected in NPC patients, contributions of these more recently discovered viral products to the establishment of TME are still vaguely defined. Further investigations are needed to delineate the mechanistic linkage of the interplay between viral and host factors, especially in relation to TME, which can be harnessed in future therapeutic strategies.

Rediscovery of NF-κB signaling in nasopharyngeal carcinoma: How genetic defects of NF-κB pathway interplay with EBV in driving oncogenesis?

Nasopharyngeal carcinoma (NPC) is a unique EBV-associated subtype of head and neck cancer, which has the highest incidence in Southern China and eastern South Asia. The interaction between genetic risk factors and environmental challenge, have been considered to contribute to the development of nasopharyngeal carcinogenesis. Constitutive activation of NF-κB signaling has been seen in NPC tissues and is associated with unfavorable prognosis. Recently, several whole exome sequencing study consistently revealed that high frequency mutations of NF-κB pathway negative regulators is common in nasopharyngeal carcinoma, which reinforce the importance of NF-κB driving oncogenesis. This review focuses on the current state of research in role of NF-κB in NPC carcinogenesis. We summarized the newly identified loss of function (LOF) mutations on NF-κB negative regulators leading to it's activation bypass LMP-1 stimulation. We discussed the critical role of NF-κB activation in immortalization and transformation of nasopharygeal epithelium. We also depicted how NF-κB signaling mediated chronic inflammation contribute to persistent EBV infection, immune evasion of EBV infected cells, metabolic reprogramming, and cancer stem cells (CSCs) formation in NPC. Lastly, we discussed the clinical resonance of targeting NF-κB for NPC precise therapy.

Prognostic role of tumour-associated macrophages and regulatory T cells in EBV-positive and EBV-negative nasopharyngeal carcinoma

AIMS

Tumour-associated macrophages (TAMs) and regulatory T cells (Tregs) form a special niche supporting tumour progression, and both correlate with worse survival in head and neck cancers. However, the prognostic role of TAM and Tregs in nasopharyngeal carcinoma (NPC) is still unknown. Therefore, we determined differences in TAMs and Tregs in different NPC subtypes, and their prognostic significance.

METHODS

Tissue of 91 NPCs was assessed for TAMs and Tregs by determination of CD68, CD163, CD206 and FOXP3 expression in the tumour microenvironment. Clinicopathological correlations were assessed using Pearson X² test, Fisher's exact test, analysis of variance and Mann-Whitney U test. Survival was analysed using Kaplan-Meier curves and Cox regression.

RESULTS

CD68 and FOXP3 counts were higher in Epstein-Barr virus (EBV)-positive NPC, while CD68-/FOXP3-, CD163+/FOXP3- and CD206+/FOXP3- infiltrates were more common in EBV-negative NPC. In the whole NPC group, CD68-/FOXP3- correlated with worse overall survival (OS), and after multivariate analysis high FOXP3 count showed better OS (HR 0.352, 95% CI 0.128 to 0.968). No difference in M2 counts existed between EBV-positive and negative NPC.

CONCLUSIONS

FOXP3, a Treg marker, seems to be an independent prognostic factor for better OS in the whole NPC group. Therefore, immune-based therapies targeting Tregs should be carefully evaluated. M2 spectrum macrophages are probably more prominent in EBV-negative NPC with also functional differences compared with EBV-positive NPC.