Lymphocyte deficiency limits Epstein-Barr virus latent membrane protein 1 induced chronic inflammation and carcinogenic pathology in vivo

The Role of EBV-Encoded LMP1 in the NPC Tumor Microenvironment: From Function to Therapy

Nasopharyngeal carcinoma (NPC) is closely associated with Epstein-Barr virus (EBV) infection. It is also characterized by heavy infiltration with non-malignant leucocytes. The EBV-encoded latent membrane protein 1 (LMP1) is believed to play an important role in NPC pathogenesis by virtue of its ability to activate multiple cell signaling pathways which collectively promote cell proliferation and survival, angiogenesis, invasiveness, and aerobic glycolysis. LMP1 also affects cell-cell interactions, antigen presentation, and cytokine and chemokine production. Here, we discuss how LMP1 modulates local immune responses that contribute to the establishment of the NPC tumor microenvironment. We also discuss strategies for targeting the LMP1 protein as a novel therapy for EBV-driven malignancies.

A central role of IKK2 and TPL2 in JNK activation and viral B-cell transformation

IκB kinase 2 (IKK2) is well known for its pivotal role as a mediator of the canonical NF-κB pathway, which has important functions in inflammation and immunity, but also in cancer. Here we identify a novel and critical function of IKK2 and its co-factor NEMO in the activation of oncogenic c-Jun N-terminal kinase (JNK) signaling, induced by the latent membrane protein 1 (LMP1) of Epstein-Barr virus (EBV). Independent of its kinase activity, the TGFβ-activated kinase 1 (TAK1) mediates LMP1 signaling complex formation, NEMO ubiquitination and subsequent IKK2 activation. The tumor progression locus 2 (TPL2) kinase is induced by LMP1 via IKK2 and transmits JNK activation signals downstream of IKK2. The IKK2-TPL2-JNK axis is specific for LMP1 and differs from TNFα, Interleukin-1 and CD40 signaling. This pathway mediates essential LMP1 survival signals in EBV-transformed human B cells and post-transplant lymphoma, and thus qualifies as a target for treatment of EBV-induced cancer.

Pathogenesis and Immune Response Caused by Vector-Borne and Other Viral Infections in a Tupaia Model

The Tupaia or tree shrew (Tupaia belangeri), a small mammal of the Tupaiidae family, is an increasingly used and promising infection model for virological and immunological research. Recently, sequencing of the Tupaia whole genome revealed that it is more homologous to the genome of humans than of rodents. Viral infections are a global threat to human health, and a complex series of events are involved in the interactions between a virus and the host immune system, which play important roles in the activation of an immune response and the outcome of an infection. Majority of immune response data in viral infections are obtained from studies using animal models that enhance the understanding of host-virus interactions; a proper understanding of these interactions is very important for the development of effective antivirals and prophylactics. Therefore, animal models that are permissive to infection and that recapitulate human disease pathogenesis and immune responses to viral infections are essential. Several studies have shown the permissiveness of Tupaia to a number of important human viral infections in vitro and in vivo without prior adaptation of the viruses; the immune responses and clinical manifestations were comparable to those observed in human infections. Thus, the Tupaia is being utilized and developed as a promising immunocompetent small animal model for viral infection studies. In this review, we focused on the immune responses, mostly innate, during viral infection and pathogenesis in the Tupaia model; we evaluated the interaction between the virus and the components of host resistance, the usefulness of this model for immunopathogenesis studies, and the vaccines and antivirals available.

TCR repertoire profiling of tumors, adjacent normal tissues, and peripheral blood predicts survival in nasopharyngeal carcinoma

The T-cell immune responses in nasopharyngeal carcinoma patients have been extensively investigated recently for designing adoptive immunotherapy or immune checkpoint blockade therapy. However, the distribution characteristics of T cells associated with NPC pathogenesis are largely unknown. We performed deep sequencing for TCR repertoire profiling on matched tumor/adjacent normal tissue from 15 NPC patients and peripheral blood from 39 NPC patients, 39 patients with other nasopharyngeal diseases, and 33 healthy controls. We found that a lower diversity of TCR repertoire in tumors than paired tissues or a low similarity between the paired tissues was associated with a poor prognosis in NPC. A more diverse TCR repertoire was identified in the peripheral blood of NPC patients relative to the controls; this was related to a significant decrease in the proportion of high-frequency TCR clones in NPC. Higher diversity in peripheral blood of NPC patients was associated with a worse prognosis. Due to the peculiarity of the Vβ gene usage patterns in the peripheral blood of NPC patients, 15 Vβ genes were selected to distinguish NPC patients from controls by the least absolute shrinkage and selection operator analysis. We identified 11 clonotypes shared by tumors and peripheral blood samples from different NPC patients, defined as "NPC-associated" that might have value in adoptive immunotherapy. In conclusion, we here report the systematic and overall characteristics of the TCR repertoire in tumors, adjacent normal tissues, and peripheral blood of NPC patients. The data obtained may be relevant to future clinical studies in the setting of immunotherapy for NPC patients.

Modulation of the tumor microenvironment by Epstein-Barr virus latent membrane protein 1 in nasopharyngeal carcinoma

Latent membrane protein 1 (LMP1) is a primary oncogene encoded by the Epstein‐Barr virus, and various portions of LMP1 are detected in nasopharyngeal carcinoma (NPC) tumor cells. LMP1 has been extensively studied since the discovery of its transforming property in 1985. LMP1 promotes cancer cell growth during NPC development and facilitates the interaction of cancer cells with surrounding stromal cells for invasion, angiogenesis, and immune modulation. LMP1 is detected in 100% of pre‐invasive NPC tumors and in approximately 50% of advanced NPC tumors. Moreover, a small population of LMP1‐expressing cells in advanced NPC tumor tissue is proposed to orchestrate NPC tumor tissue maintenance and development through cancer stem cells and progenitor cells. Recent studies suggest that LMP1 activity shifts according to tumor development stage, but it still has a pivotal role during all stages of NPC development.

N-acetylcysteine (NAC) ameliorates Epstein-Barr virus latent membrane protein 1 induced chronic inflammation

Chronic inflammation results when the immune system responds to trauma, injury or infection and the response is not resolved. It can lead to tissue damage and dysfunction and in some cases predispose to cancer. Some viruses (including Epstein-Barr virus (EBV)) can induce inflammation, which may persist even after the infection has been controlled or cleared. The damage caused by inflammation, can itself act to perpetuate the inflammatory response. The latent membrane protein 1 (LMP1) of EBV is a pro-inflammatory factor and in the skin of transgenic mice causes a phenotype of hyperplasia with chronic inflammation of increasing severity, which can progress to pre-malignant and malignant lesions. LMP1 signalling leads to persistent deregulated expression of multiple proteins throughout the mouse life span, including TGFα S100A9 and chitinase-like proteins. Additionally, as the inflammation increases, numerous chemokines and cytokines are produced which promulgate the inflammation. Deposition of IgM, IgG, IgA and IgE and complement activation form part of this process and through genetic deletion of CD40, we show that this contributes to the more tissue-destructive aspects of the phenotype. Treatment of the mice with N-acetylcysteine (NAC), an antioxidant which feeds into the body’s natural redox regulatory system through glutathione synthesis, resulted in a significantly reduced leukocyte infiltrate in the inflamed tissue, amelioration of the pathological features and delay in the inflammatory signature measured by in vivo imaging. Reducing the degree of inflammation achieved through NAC treatment, had the knock on effect of reducing leukocyte recruitment to the inflamed site, thereby slowing the progression of the pathology. These data support the idea that NAC could be considered as a treatment to alleviate chronic inflammatory pathologies, including post-viral disease. Additionally, the model described can be used to effectively monitor and accurately measure therapies for chronic inflammation.

A study of Epstein-Barr virus infection in the Chinese tree shrew(Tupaia belangeri chinensis)

Background

Epstein–Barr virus (EBV) is closely associated with many human diseases, including a variety of deadly human malignant tumours. However, due to the lack of ideal animal models,the biological characteristics of EBV, particularly its function in tumourigenesis, have not been determined. Chinese tree shrews (Tupaia belangeri chinensis), which are similar to primates, have been used to establish a variety of animal models and have recently received much attention. Here, we established tree shrews as a model for EBV infection by intravenous injection.

Methods

Ten tree shrews were inoculated with EBV by intravenous injection,and blood was collected at regular intervals thereafter from the femoral artery or vein to detect EBV markers.

Results

Eight of 10 tree shrews showed evidence of EBV infection. In the 8 EBV-infected tree shrews, EBV copy number increased intermittently or transiently, EBV-related gene expression was detected, and anti-EBV antibodies increased to varying degrees. Macroscopic hepatomegaly was observed in 1 tree shrew, splenomegaly was observed in 4 tree shrews, and enlarged mesenteric lymph nodes were observed in 3 tree shrews. Haematoxylin and eosin (HE) staining showed splenic corpuscle hyperplasia in the spleens of 4 tree shrews and inflammatory cell infiltration of the liver of 1 tree shrew and of the mesenteric lymph nodes of 3 tree shrews. EBER in situ hybridization(ISH) and immunohistochemical (IHC) staining showed that EBER-, LMP1- and EBNA2- positive cells were present in the spleens and mesenteric lymph nodes of some tree shrews. Western blotting (WB) revealed EBNA1-positive cells in the spleens of 4 tree shrews. EBV markers were not detected by HE, EBER-ISH or IHC in the lung or nasopharynx.

Conclusions

These findings suggest that EBV can infect tree shrews via intravenous injection. The presented model offers some advantages for exploring the pathophysiology of EBV infection in humans.

Prognostic significance of tumour infiltrating B lymphocytes in breast ductal carcinoma in situ

AIMS

Tumour-infiltrating lymphocytes (TILs) are an important component of the immune response to cancer and have a prognostic value in breast cancer. Although several studies have investigated the role of T lymphocytes in breast cancer, the role of B lymphocytes (TIL-Bs) in ductal carcinoma in situ (DCIS) remains uncertain. This study aimed to assess the role of TIL-Bs in DCIS.

METHODS AND RESULTS

Eighty DCIS cases (36 pure DCIS and 44 mixed with invasive cancer) were stained immunohistochemically for B lineage markers CD19, CD20 and the plasma cell marker CD138. TIL-Bs density and localization were assessed, including relation to the in-situ and invasive components. An association with clinicopathological data and patient outcome was performed. Pure DCIS showed a higher number of TIL-Bs and lymphoid aggregates than DCIS associated with invasion. In pure DCIS, a higher number of peri- and paratumoral TIL-Bs was associated significantly with large tumour size (P = 0.016), hormone receptor (ER/PR) negative (P = 0.008) and HER2⁺ status (P = 0.010). In tumours with mixed DCIS and invasive components, cases with high-density B lymphocytes, irrespective of their location or topographic distribution, were associated significantly with variables of poor prognosis, including larger size, high grade, lymphovascular invasion, lymph node metastases, ER/PR-negative and HER2⁺ status. Outcome analysis showed that pure DCIS associated with higher numbers of B lymphocytes had shorter recurrence-free interval (P = 0.04); however, the association was not significant with the CD138⁺ plasma cell count (P = 0.07).

CONCLUSION

Assessment of TIL-B cells based on location and topographic distribution can provide prognostic information. Validation in a larger cohort is warranted.

The Latent Membrane Protein 1 (LMP1)

Almost exactly twenty years after the discovery of Epstein-Barr virus (EBV), the latent membrane protein 1 (LMP1) entered the EBV stage, and soon thereafter, it was recognized as the primary transforming gene product of the virus. LMP1 is expressed in most EBV-associated lymphoproliferative diseases and malignancies, and it critically contributes to pathogenesis and disease phenotypes. Thirty years of LMP1 research revealed its high potential as a deregulator of cellular signal transduction pathways leading to target cell proliferation and the simultaneous subversion of cell death programs. However, LMP1 has multiple roles beyond cell transformation and immortalization, ranging from cytokine and chemokine induction, immune modulation, the global alteration of gene and microRNA expression patterns to the regulation of tumor angiogenesis, cell-cell contact, cell migration, and invasive growth of tumor cells. By acting like a constitutively active receptor, LMP1 recruits cellular signaling molecules associated with tumor necrosis factor receptors such as tumor necrosis factor receptor-associated factor (TRAF) proteins and TRADD to mimic signals of the costimulatory CD40 receptor in the EBV-infected B lymphocyte. LMP1 activates NF-κB, mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3-K), IRF7, and STAT pathways. Here, we review LMP1's molecular and biological functions, highlighting the interface between LMP1 and the cellular signal transduction network as an important factor of virus-host interaction and a potential therapeutic target.

Differential immune cell densities in ductal carcinoma In-Situ and invasive breast cancer: Possible role of leukocytes in early stages of carcinogenesis

Objectives:

To investigate immune cell densities in pre-neoplastic (DCIS), cancer (IDC) and control breast tissues.

Methods:

A total of four preneoplastic, 104 cancer and 104 control samples were analyzed. Morphological classification and prognostic scoring along with quantification of immune cells/mm² was performed. Data were entered and analyzed using SPSS version 16. Correlation of immune cell densities with various tumour sub-types was investigated using paired t-test and ANOVA. A p-value of <0.05 was considered as significant.

Results:

Our data show increased infiltration of lymphocytes (mean lymphocytes = 287.6cells/mm²) as well as myelocytes (mean lymphocytes = 117.1cells/mm²) in pre-neoplastic tissues. This infiltration was significantly high compared to cancer (p-value<0.001) as well as control tissues (p-value <0.001). Moreover, we report increased infiltration of lymphocytes in cancer tissues compared to controls (p-value<0.001). There was no difference in lymphocyte densities within various tumour sub-types (all p-values >0.05).

Conclusion:

Leukocytes may play a role in early stages of breast carcinogenesis.

Histone demethylase RBP2 induced by Helicobactor Pylori CagA participates in the malignant transformation of gastric epithelial cells

Gastric epithelial cell malignant transformation induced by Helicobactor Pylori contributes to tumor development, but the underlying mechanisms for this remain unclear. Here we demonstrate that RBP2, a newly identified histone demethylase, can be induced by CagA via PI3K/AKT-Sp1 pathway depending on AKT phosphorylation. Sp1 directly binds to RBP2 promoter and enhances its expression then the upregulated RBP2 significantly increases Cyclin D1 transcription, which contributes to gastric epithelial cell malignant transformation. Further data indicate that knockdown of endogenous RBP2 dominantly inhibits gastric cancer (GC) development both in vitro and in vivo. In conclusion, this CagA- PI3K/AKT-Sp1-RBP2-Cyclin D1 pathway may serve as a novel mechanism for gastric epithelial cell malignant transformation and then gastric cancer (GC). Therefore, RBP2 may link chronic inflammation to tumor development and its inhibition may have potential therapeutic advantages.

EBV oncogene N-LMP1 induces CD4 T cell-mediated angiogenic blockade in the murine tumor model

Antivascular immunity may provide long-term protection by preventing neovascularization that precedes tumor progression. Although the tumorigenesis promoted by EBV-encoded oncogene latent membrane protein 1 derived from Taiwanese nasopharyngeal carcinoma (N-LMP1) has been demonstrated, the potential of N-LMP1 for inducing immune surveillance remains elusive. In this article, we describe the immunogenicity of N-LMP1 (1510) and its induction of antivascular immunity in a transplantable tumor model in immunocompetent BALB/c mice. The immunogenicity of N-LMP1 was evaluated on the basis of tumor rejection following immunization. The impact of the immunization on the dynamics of tumor angiogenesis was assessed by temporal noninvasive dynamic contrast-enhanced magnetic resonance imaging and was further confirmed by histologic study and vascular count. Through the experiments of in vivo depletion and adoptive transfer, CD4 T cells were identified as effectors that depend on IFN-γ for tumor prevention. The response was further verified by the identification of an MHC H-2 I-E(d)-restricted peptide derived from N-LMP1 and by the immunization of mice with N-LMP1 peptide-loaded dendritic cells. These studies provide insight into N-LMP1-specific immunity in vivo, which suggests that CD4 T cells may play an important role in angiogenic surveillance against LMP1-associated cancer via tumor stroma targeting.

Phosphatidylinositol 3-kinase (PI3K) inhibitors as cancer therapeutics

Phosphatidylinositol 3-kinases (PI3Ks) are lipid kinases that regulate diverse cellular processes including proliferation, adhesion, survival, and motility. Dysregulated PI3K pathway signaling occurs in one-third of human tumors. Aberrantly activated PI3K signaling also confers sensitivity and resistance to conventional therapies. PI3K has been recognized as an attractive molecular target for novel anti-cancer molecules. In the last few years, several classes of potent and selective small molecule PI3K inhibitors have been developed, and at least fifteen compounds have progressed into clinical trials as new anticancer drugs. Among these, idelalisib has advanced to phase III trials in patients with advanced indolent non-Hodgkin's lymphoma and mantle cell lymphoma. In this review, we summarized the major molecules of PI3K signaling pathway, and discussed the preclinical models and clinical trials of potent small-molecule PI3K inhibitors.

Identification of transmembrane protein 134 as a novel LMP1-binding protein by using bimolecular fluorescence complementation and an enhanced retroviral mutagen

Latent membrane protein 1 (LMP1) of Epstein-Barr virus induces constitutive signaling in infected cells. LMP1 signaling requires oligomerization of LMP1 via its transmembrane domain, localization to lipid rafts in the membrane, and association of the LMP1 cytoplasmic domain to adaptor proteins, such as the tumor necrosis factor receptor-associated factors (TRAFs). Protein complementation is a novel technique to examine protein-protein interaction through the assembly of functional fluorescent proteins or enzymes from inactive fragments. A previous study in our lab demonstrated the use of bimolecular fluorescence complementation (BiFC) to study the assembly of the LMP1 signaling complexes within the plasma membrane of mammalian cells. In the present study, LMP1 was used as bait in a genome-wide BiFC screen with an enhanced retroviral mutagen to identify new LMP1-binding proteins. Our screen identified a novel LMP1-binding protein, transmembrane protein 134 (Tmem134). Tmem134 is a candidate oncogene that is amplified in breast cancer cell lines. Binding, colocalization, and cofractionation between LMP1 and Tmem134 were confirmed. Finally, Tmem134 affected LMP1-induced NF-κB induction. Together, these data suggest that BiFC is a unique and novel platform to identify proteins recruited to the LMP1-signaling complex.

Chitinase-like proteins are autoantigens in a model of inflammation-promoted incipient neoplasia

An important role for B cells and immunoglobulin deposition in the inflammatory tumor cell environment has been recognized in several cancers, and this is recapitulated in our murine model of inflammation-associated carcinogenesis: transgenic mice expressing the Epstein-Barr virus oncogene LMP1 in epithelia. Similarly in several autoimmune disorders, immunoglobulin deposition represents a key underlying event in the disease process. However, the autoantigens in most cases are not known. In other studies, overexpression of the enzymatically inactive mammalian chitinase-like proteins (CLPs) has been observed in a number of autoimmune disorders and numerous cancers, with expression correlated with poor prognosis, although the function of these proteins is largely unknown. We have now linked these observations demonstrating that overexpression of the CLPs renders them the targets for autoantigenicity during carcinogenic progression. We show that the CLPs, Chi3L1, Chi3L3 /YM1, and Chi3L4/YM2, are abundantly overexpressed in the transgenic epidermis at an early, preneoplastic stage and secreted into the serum. Immunoglobulin G reactive to the CLPs is detected in the serum and deposited in the hyperplastic tissue, which goes on to become inflamed and progressively displastic. The CLPs are also upregulated in chemical carcinogen-promoted lesions in both transgenic and wild-type mice. Expression of the related, active chitinases, Chit1 and AMCase, increases following infiltration of inflammatory cells. In this model, the 3 CLPs are autoantigens for the tissue-deposited immunoglobulin, which we propose plays a causative role in promoting the inflammation-associated carcinogenesis. This may reflect their normal, benign function to promote tissue remodeling and to amplify immune responses. Their induction during carcinogenesis and consequent autoantigenicity provides a missing link between the oncogenic event and subsequent inflammation. This study identifies the CLPs as important and novel therapeutic targets to limit inflammation in cancer and potentially also autoimmune disorders.

Localization of Epstein-Barr virus to infiltrating lymphocytes in breast carcinomas and not malignant cells

The pathogenesis of breast cancer is unknown. In recent years, a number of studies have implicated a role for Epstein-Barr virus (EBV) in a subset of cases. However, these findings are controversial and others have failed to find any link between the virus and this malignancy. We hypothesized that technical differences and the different type and ethnic origin of the cases may be the cause of the disparities reported. Using a highly sensitive EBER-in situ hybridization and immunohistochemistry, we examined 219 samples (158 malignant and 61 non-malignant) from 61 Emirati breast cancer cases to determine if EBV was etiologically associated with Emirati cases and if there was any correlation with other established prognostic factors such as age, histological type, lymph node metastasis, estrogen, progesterone and HER2 expression. We found 47.5% of the cases to be EBV positive, but the virus was localized to occasional infiltrating lymphocytes and not in the malignant cells. EBV lymphocytes were more commonly observed in lymph nodes than in breast tissues, but there was no correlation with malignancy or hormone status. The mean age of our patients was 48years and hormone receptor staining revealed 20% of the cases to be triple negative (ER-/PR-/HER2-). We conclude that although EBV can be detected in breast cancer cases, it is not directly associated with the disease. Thus, a PCR-based approach cannot be used to link this ubiquitous virus to the pathogenesis of breast cancer. Furthermore, we do not find any correlation between the presence of EBV in infiltrating lymphocytes and ER, PR, HER2 expression. We believe our findings will help explain some of the controversies relating to the role of EBV in the pathogenesis of breast cancer.