Latent Membrane Protein Research Articles

Latent Membrane Protein 1 Antibody Inhibited Cell Stemness Growth of Nasopharyngeal Carcinoma by Regulating PI3K/AKT Signaling Pathway

Objective: The aim of the study was to investigate the effects of LMP1-Fab antibody on Nasopharyngeal carcinoma (NPC) cancer stem cells (CSCs). Methods/Results: LMP1 was identified to play an important role in maintaining the stemness characteristics of NPC by sphere formation, as is evidenced by CCK-8 and colony formation assays. Furthermore, CCK8 and TUNEL assays indicated that LMP1-Fab antibody could accelerate cell apoptosis while inhibiting cell proliferation in nasopharyngeal carcinoma stem cell. Notably, LMP1-Fab antibody inhibited NPC xenograft cancer growth in the nude mice. At the molecular level, LMP1-Fab antibody inhibited the phosphorylation of PI3K/AKT signaling pathway both in vitro and in vivo. More importantly, these effects were blocked by PI3K/AKT phosphorylation inhibitor LY294002. Conclusion: These results suggested that the novel antibody-targeting LMP1 is likely to be a promising strategy for the treatment of NPC.

The Clinical Significance of IGF-1R and Relationship with Epstein-Barr Virus Markers: LMP1 and EBERs in Tunisian Patients with Nasopharyngeal Carcinoma.

Tunisia is in the endemic area of nasopharyngeal carcinoma. Epstein-Barr virus (EBV) based assays have been commonly used as standard markers for screening and monitoring the disease. So, it is very important to find novel factors for the early diagnostic and prognostic evaluation of this cancer. The aim of the study was to evaluate the expression of IGF-1R (Insulin Growth Factor Receptor 1), LMP 1 (Latent Membrane Protein 1) and EBERs (EBV encoded RNAs) in order to determine their correlation with clinicopathologic parameters and survival rates in patients with nasopharyngeal carcinoma (NPC). We also looked for the relationship between these biomarkers. IGF-1R and LMP1 expression was performed by means of immunohistochemical method and EBERs were detected using in situ hybridization of paraffin embedded tumor tissues of 94 patients with nasopharyngeal carcinoma and 45 non-cancerous nasopharyngeal mucosa samples. Our findings demonstrated that IGF-1R was over expressed in 47.87% of NPC patients and only in 2.22% of controls. Positive LMP1 expression was detected in 56.38% of NPC patients and all NPC patients were positive for the EBV-encoded RNAs staining. A statistically significant positive correlation was observed between IGF-1R expression and the tumor size (P < .001). Kaplan-Meier survival curves showed that NPC patients with a strong IGF-1R expression level have shorter median and 5-year Overall Survival than those with weak expression rates (100.15 vs 102.68 months, P = .08). In addition, median and 5-year Disease-Free Survival was significantly lower in the LMP1 positive NPC patients than in the LMP1 negative ones (53.38 vs 93.37 months, P = .03). Moreover, LMP1 expression correlated strongly with IGF-1R expression (P = .018). The relationship between these two biomarkers could influence patient survival. IGF1-R and LMP1 could be valuable prognostic markers in Tunisian NPC patients.

The Epstein-Barr virus and osteosarcoma in Iranian children.

e23543 Background: This study was conducted to describe the possible association between EBV infection and OS in Iranian children. Methods: This study carried out at Kermanshah university hospital on 48 OS tissue and ten non-cancerous bone tissue as a control group by three laboratory methods. The real-time polymerase chain reaction (RT-PCR) and Chromogenic in-situ hybridization (CISH) done to detect the Epstein Barr Encoded RNA (EBER1) expression as long as immunohistochemistry staining (IHC) to detect EBV latent membrane protein-1 (LMP-1) in tumor cells and controls. Overall-survival (O-S), prognosis free survival (PFS) and disease-free survival (DFS) provided based on the Kaplan-Meier method. Results: Specimen considered positive when EBER using PCR and CISH associated with LMP-1 using IHC stain were expressed separately in the same sample. Six out of eighty-four (12.5%) of OS cases were simultaneously EBV positive in all three methods within the tumor cells as compared to the control group. (P &lt; 0.22) Association between EBV positivity and histologic characteristics of OS cases such as nodal involvement (P &lt; 0.04), metastasis (P &lt; 0.04), Ki67 reactivity (as proliferation index) (P &lt; 0.03), and tumor stage (P &lt; 0.05) were significant. EBV Positive patients show worse clinical symptoms in older age as well as the worse prognosis compared with negative patients. EBV positive patients presented shorter DFS, PFS, and OS. Conclusions: Our research could not find a statistical association between EBV infection and OS in Iranian children significantly. Meanwhile, we found, EBV infection could interfere in the invasive behavior of tumors. [Table: see text]

Drp1-dependent remodeling of mitochondrial morphology triggered by EBV-LMP1 increases cisplatin resistance

Latent membrane protein 1 (LMP1) is a major Epstein–Barr virus (EBV)-encoded oncoprotein involved in latency infection that regulates mitochondrial functions to facilitate cell survival. Recently, mitochondrial fission has been demonstrated as a crucial mechanism in oncovirus-mediated carcinogenesis. Mitochondrial dynamin-related protein 1 (Drp1)-mediated mitochondrial fission has an impact on the chemoresistance of cancers. However, the mechanism by which oncogenic stress promotes mitochondrial fission, potentially contributing to tumorigenesis, is not entirely understood. The role of Drp1 in the oncogenesis and prognosis of EBV-LMP1-positive nasopharyngeal carcinoma (NPC) was determined in our study. We show that EBV-LMP1 exhibits a new function in remodeling mitochondrial morphology by activating Drp1. A high level of p-Drp1 (Ser616) or a low level of p-Drp1 (Ser637) correlates with poor overall survival and disease-free survival. Furthermore, the protein level of p-Drp1 (Ser616) is related to the clinical stage (TNM stage) of NPC. Targeting Drp1 impairs mitochondrial function and induces cell death in LMP1-positive NPC cells. In addition, EBV-LMP1 regulates Drp1 through two oncogenic signaling axes, AMPK and cyclin B1/Cdk1, which promote cell survival and cisplatin resistance in NPC. Our findings provide novel insight into the role of EBV-LMP1-driven mitochondrial fission in regulating Drp1 phosphorylation at serine 616 and serine 637. Disruption of Drp1 could be a promising therapeutic strategy for LMP1-positive NPC.

Dendritic cell therapy with CD137L-DC-EBV-VAX in locally recurrent or metastatic nasopharyngeal carcinoma (NPC).

6535 Background: Epstein-Barr virus (EBV) is associated with non-keratinising (NK) NPC, a disease prevalent in Southeast Asia, and provides a potential target for dendritic cell (DC) vaccine therapy. CD137 ligand (CD137L) expressed on antigen presenting cells costimulates CD137 expressing T cells upon receptor/ligand interaction. CD137L signalling differentiates monocytes to CD137L-DC, a novel type of DC, which are more potent than classical DC in stimulating autologous T cells. Here, we explore the safety and efficacy of autologous CD137L-DC pulsed with EBV peptides spanning Epstein Barr nuclear antigen 1, latent membrane protein 1 (LMP1) and LMP2 (CD137L-DC-EBV-VAX) in patients with locally recurrent or metastatic NPC. Methods: In this single centre, phase I study, eligible patients (pts) with locally recurrent or metastatic NK-NPC and clinical benefit (CB) from their prior treatment (stable disease [SD], partial [PR] or complete response[CR]), underwent apheresis to isolate monocytes which were differentiated to CD137L-DC through CD137L agonist exposure. CD137L-DC were pulsed with EBV antigens during maturation to obtain CD137L-DC-EBV-VAX which was administered intradermally every 2 weeks (w) for up to 7 injections following site preconditioning with Tetanus and Diphtheria vaccine. Results: 14 pts were enrolled of which 2 progressed rapidly and did not begin treatment. Mean age was 58 years. Median lines of prior treatment for metastatic NPC was 1 (range 1-6), the most common being cisplatin and gemcitabine. 9 pts received 7 vaccine doses (range 2-7) with a mean administered cell count of 23.9x106. CB was seen in 5 cases (42%) with 1 PR and 4 SD beyond 1 year. Median progression free survival (mPFS) was 26w (95% CI, 23-43). The lowest PFS (8w) was in a pt with 6 prior lines of treatment including a checkpoint inhibitor. Mean pretreatment neutrophil: lymphocyte ratio (NLR) was 3.4 and a value of less than 3 was associated with prolonged mPFS (42 vs 14w, p = 0.01). Enzyme linked immune absorbent spot (ELISPOT) analysis in 5 pts with CB showed a rise in interferon-γ secreting peripheral T cells prior to the 3rd vaccine versus baseline. Treatment was well tolerated with only 4 cases of grade 1 related adverse events reported, most commonly injection site reaction (3pts). Conclusions: CD137L-DC-EBV-VAX is safe and exhibits promising efficacy when administered following CB from chemotherapy. A rise in activated peripheral blood mononuclear cells after 2 vaccinations in selected patients showing benefit suggests immunological correlates with efficacy. Clinical trial information: NCT03282617 .

Cancer stem cells in Epstein-Barr virus-associated gastric carcinoma.

Cancer stem cells (CSCs) play a decisive role in the development and progression of cancer. To investigate CSCs in Epstein‐Barr virus (EBV)‐associated carcinoma (EBVaGC), we screened previously reported stem cell markers of gastric cancer in EBV‐infected gastric cancer cell lines (TMK1 and NUGC3) and identified CD44v6v9 double positive cells as candidate CSCs. CD44v6/v9+/+ cells were sorted from EBVaGC cell line (SNU719) cells and EBV‐infected TMK1 cells and these cell populations showed high spheroid‐forming ability and tumor formation in SCID mice compared with the respective CD44v6/v9−/− cells. Sphere‐forming ability was dependent on the nuclear factor‐κB (NF‐κB) signaling pathway, which was confirmed by decrease of sphere formation ability under BAY 11‐7082. Small interfering RNA knockdown of latent membrane protein 2A (LMP2A), one of the latent gene products of EBV infection, decreased spheroid formation in SNU719 cells. Transfection of the LMP2A gene increased the sphere‐forming ability of TMK1 cells, which was mediated through NF‐κB signaling. Together, these results indicate that CD44v6v9+/+ cells are CSCs in EBVaGC that are maintained through the LMP2A/NF‐κB pathway. Future studies should investigate CD44v6/v9+/+ cells in normal and neoplastic gastric epithelium to prevent and treat this specific subtype of gastric cancer infected with EBV.

DNA methylation enzymes and PRC1 restrict B-cell Epstein-Barr virus oncoprotein expression.

To accomplish the remarkable task of lifelong infection, Epstein-Barr virus (EBV) switches between four viral genome latency and lytic programs to navigate the B-cell compartment and evade immune responses. The transforming program, comprised of highly immunogenic EBV nuclear antigen (EBNA) and Latent Membrane Proteins (LMP), is expressed in newly infected B-lymphocytes and in post-transplant lymphomas. Upon memory cell differentiation and in most EBV-associated Burkitt lymphomas (BL), all but one viral antigen are repressed for immunoevasion. To gain insights into epigenetic mechanisms that restrict immunogenic oncoprotein expression, a genome-scale CRISPR/Cas9 screen was performed in EBV+ BL cells. Here we show that the ubiquitin ligase UHRF1 and its DNA methyltransferase partner DNMT1 were critical for restriction of EBNA and LMP expression. All UHRF1 reader and writer domains were necessary for silencing, and DNMT3B was identified as an upstream viral genome CpG methylation initiator. Polycomb repressive complex I exerted a further layer of control over LMP expression, suggesting a second mechanism for latency program switching. UHRF1, DNMT1 and DNMT3B are upregulated in germinal center B-cells, the BL cell of origin, providing a molecular link between B-cell state and EBV latency program. These results suggest rational therapeutic targets to manipulate EBV oncoprotein expression.

Evaluation of the effect of 5-aminolevulinic acid hexyl ester (H-ALA) PDT on EBV LMP1 protein expression in human nasopharyngeal cells.

Nasopharyngeal carcinoma (NPC) is of high prevalence in Hong Kong and southern China. The pathogenesis of NPC is closely associated with Epstein-Barr virus (EBV) infection via regulation of viral oncoprotein latent membrane protein 1 (LMP1). The conventional treatment for NPC is chemo-radiotherapy, but the prognosis remains poor for advanced stage, recurrent and metastatic NPC. Photodynamic therapy (PDT) is a therapeutic approach to combat tumors. PDT effectiveness depends on the interaction of photosensitizers, light and molecular oxygen. 5- aminolevulinic acid hexyl derivative (H-ALA) is one of the photosensitizers derived from 5-ALA. H-ALA with improved lipophilic properties by adding a long lipophilic chain (hexyl group) to 5-ALA, resulted in better penetration into cell cytoplasm. In this study, the effect of H-ALA-PDT on NPC cells (EBV positive C666-1 and EBV negative CNE2) was investigated. The H-ALA mediated cellular uptake and cytotoxicity was revealed via flow cytometry analysis and MTT assay respectively. H-ALA PDT mediated protein modulation was analysed by western blot analysis. Our finding reported that the cellular uptake of H-ALA in C666-1 and CNE2 cells was in a time dependent manner. H-ALA PDT was effective to C666-1 and CNE2 cells. EBV LMP1 proteins was expressed in C666-1 cells only and its expression was responsive to H-ALA PDT in a dose dependent manner. This work revealed the potential of H-ALA PDT as a treatment regiment for EBV positive NPC cells. Understanding the mechanism of H-ALA mediated PDT could develop improved strategies for the treatment of NPC.

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English

Association of Epstein- Barr Virus (EBV) with the Development of Nasopharyngeal Carcinoma (NPC) in Western Region of Iraq: Unmatched Molecular Case-Control Study

Background: Nasopharyngeal Carcinoma (NPC) is uncommon in Iraq, but its incidence is raising due to increased exposure to diverse risk factors. Many of the NPC-related risk factors are becoming more and more apparent in Iraq. The exactly risk factors for nasopharyngeal carcinoma (NPC) in Anbar province, Iraq are not known. Objectives: To determine the association between Epstein- Barr virus (EBV) infections and other risk factors with the development NPC of Iraqi patients. Patients and Method: Sixty-seven paraffin-embedded tissues of NPC cases, 134 normal noncancerous nasopharyngeal biopsy samples, and tonsillectomy specimens from patients with chronic hypertrophic tonsillitis as controls were enrolled in the study that was conducted between 12 January 2012 and 21 January 2019. DNA of EBV was extracted from both controls and neoplastic tissues and analyzed by PCR technique using primers specific to EBV Latent Membrane Protein-1 Oncogene (LAMP-1) for the presence of EBV. A Questioners data form for all patients and controls were filled by the researchers regarding other risk factors of NPC including the patient’s age, sex, residence, radiation exposure, history of chronic rhinitis, family history of NPC, tobacco smoking, alcohol consumption, herbal medicines, tea consumption, exposure to formaldehyde and exposure to different inhalants. Results: The following risk factors were found to be independently associated with illness: EBV (adjusted odds ratio [OR] 7.852, 95% confidence interval [CI] 2.22–27.72), herbal medicine (OR 19.051, CI 7.56– 47.95) and Family history of NPC (OR 63.717, CI 6.67–607.96). Conclusion: Combination of family history of NPC , EBV exposure and herbal medicine was a strong risk factor for NPC.

Epstein–Barr virus LMP1 oncogene polymorphism in tatar and slavic populations in Russian Federation impacting on some malignant tumours

Objective: To compare genetic structure of the main Epstein–Barr virus (EBV) oncogene, latent membrane protein 1 (LMP1), in EBV strains circulating in two genetically distinct ethnic populations in Russian Federation, Tatars and Slavs, as well as assess an impact of diverse LMP1 variants on incidence and mortality rate for some malignant tumors partially associated with EBV infection. Materials and methods. Oral washing samples were collected from 60 ethnic Kazan Tatars and 65 ethnic Moscow Slavics. Carboxy-terminal nucleotide sequences (41 and 40 sequences, respectively) derived from hypervariable LMP1 gene region were amplified from EBV DNA samples. Next, final nucleotide sequences were translated into amino acid sequences and analyzed according to classification by Edwards et al. Results. Analysis of 41 and 40 LMP1 samples obtained from ethnic Kasan Tatars and ethnic Moscow Slavics, respectively, revealed significant difference in relevant amino acid structures. In particular, all LMP1 samples derived from Moscow Slavics were found to belong to the four protein variants: B95.8/A, Med–, China1 and NC. Among them, low-transforming variant B95.8/A was dominant (82.5%). In contrast, solely 21 out of 41 LMP1 samples derived from ethnic Tatars were classified as B95.8/A, Med– and China1 variants. Importantly, the percentage of low-transforming B95.8/A variant among ethnic Tatar samples was significantly lower compared to that one found in Moscow Slavics (29.3% vs. 82.5%). On the other hand, seven (17.1%) out of 20 other samples formed a unique protein mono group characterized by LMP1 amino acid sequence differed from that one available in the GenBank database. Such group of variants was designated as LMP1-TatK. The remaining 13 samples (31.7%) did not match either protein variants, thereby forming the “beyond classification” (LMP1-TatBC) group. Conclusion. The data obtained suggest that various LMP1 variants exist in EBV strains persisting in ethnic Tatrs and ethnic Slavics examined in Russian Federation. It was also found that EBV strains isolated from ethnic Tatars contained a unique LMP1 gene variant encoding protein LMP1-TatK lacked in EBV strains derived from ethnic Moscow Slavics. Taking into account the genealogy of Tatars, it cannot be ruled out that EBV strain bearing LMP1-TatK variant represented ethnically specific EBV strain that might circulate many centuries ago among their historical human predecessors called Mongol-Tatar tribes. In addition, it was shown that the LMP1 variants in EBV strains isolated from ethnic Kazan Tatars and ethnic Moscow Slavics did not affect the incidence and mortality of different forms of cancer consisting of EBV-associated cases.

CD47 Overexpression Is Associated with Epstein-Barr Virus Infection and Poor Prognosis in Patients with Nasopharyngeal Carcinoma.

PurposeLittle is known about the clinical significance of CD47 expression and its association with Epstein–Barr virus (EBV) infection in patients with nasopharyngeal carcinoma (NPC). The aim of this study was to clarify the prognostic value and role of CD47 in EBV-associated NPC.Materials and MethodsSixty-six cases of non-metastatic NPC were retrospectively reviewed. Tissues were collected for immunohistochemical staining of CD47 and the EBV-encoded oncoprotein latent membrane protein 1 (LMP1). Western blotting and quantitative real-time PCR were performed to determine the CD47 and LMP1 levels in common human NPC cell lines. Additionally, CD47 and LMP1 expression in a constructed EBV-positive human NPC cell (CNE-2-EBV+) and a stable cell line transfected with LMP1 plasmid (CNE-2-LMP1) was assessed. Next, we used Western blotting to assess the decrease in CD47 expression on CNE-2-LMP1 cells after transfecting them with small interfering RNA (siRNA)-targeting LMP1.ResultsIn NPC patients, CD47 overexpression was significantly associated with disease recurrence (P=0.010), leading to poorer disease-free survival (DFS; P=0.002) and overall survival (P=0.021). Multivariate Cox proportional hazards models demonstrated that CD47 (HR=5.452, P=0.016) was an independent prognostic factor of DFS. Moreover, CD47 expression was associated with plasma EBV-DNA copy number and LMP1 tissue expression. Among the human NPC cell lines, CD47 and LMP1 expression was notably higher in the EBV-positive C666-1 cell line than in the EBV-negative cell lines. Furthermore, EBV infection upregulated CD47 expression via LMP1-mediated pathways in human NPC cells.ConclusionThis study indicated that CD47 is related to EBV infection in NPC patients, and it is a feasible biomarker.

Assessing the potential association between Epstein-Barr virus and oral squamous cell carcinoma: a systematic review and meta-analysis.

BackgroundThis study aims to qualitatively and quantitatively review the association between Epstein-Barr virus (EBV) and oral squamous cell carcinoma (OSCC).MethodsPubMed, Scopus, and Web of Science databases were searched using the keywords “EBV or Epstein Barr virus and Oral cancer or Oral squamous cell carcinoma” for published case-control studies in the English language upto August 2019.ResultsThe search yielded 985 articles out of which 966 articles were excluded by screening their titles and abstracts as they were irrelevant or duplicates. Based on the full-text assessment of the remaining 19 articles, only 7 satisfied the inclusion criteria and were included in the qualitative analysis, out of which only 4 were compatible to be included in the meta-analysis. The diagnostic modalities used included immunohistochemistry, in situ hybridization and polymerase chain reaction. The diagnostic targets included latent membrane protein (LMP)-1, EBV determined nuclear antigen-1, EBV-encoded small non-polyadenylated RNA-2. The meta-analysis showed that there is an association between the EBV and OSCC.ConclusionsDetermining the association of EBV with OSCC is highly tedious due to the contrasting data obtained from individuals’ studies which in turn is due to the wide variations in the sensitivity and specificity of the diagnostic modalities used and diagnostic targets selected. Although the meta-analysis revealed an association between EBV and OSCC, the number and the quality of the studies included in the meta-analysis are limited, thus the association requires further validation for any conclusive inference.

Generation of novel affibody molecules targeting the EBV LMP2A N-terminal domain with inhibiting effects on the proliferation of nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) induced by latent infection with Epstein-Barr virus (EBV) remains the most common head and neck cancer in Southeast Asia, especially in the southern part of China. It is well known that persistent expression of two EBV latent membrane proteins (LMP1/LMP2A) plays a key role in nasopharyngeal carcinogenesis. Therefore, the therapeutic approach of targeting the LMP1/LMP2A protein and subsequently blocking the LMP1/LMP2A-mediated signalling pathway has been considered for treating patients with NPC. Recently, affibody molecules, a new class of small (~6.5 kDa) affinity proteins, have been confirmed to be powerful generalisable tools for developing imaging or therapeutic agents by targeting specific molecules. In this study, three EBV LMP2A N-terminal domain-binding affibody molecules (ZLMP2A-N85, ZLMP2A-N110 and ZLMP2A-N252) were identified by screening a phage-displayed peptide library, and their high affinity and specificity for the EBV LMP2A N-terminal domain were confirmed by surface plasmon resonance (SPR), indirect immunofluorescence, co-immunoprecipitation and near-infrared small animal fluorescence imaging in vitro and in vivo. Moreover, affibody molecules targeting the EBV LMP2A N-terminal domain significantly reduced the viability of the EBV-positive cell lines C666-1, CNE-2Z and B95-8. Further investigations showed that affibody ZLMP2A-N110 could inhibit the phosphorylation of AKT, GSK-3β and β-catenin signalling proteins, leading to suppression of β-catenin nuclear translocation and subsequent inhibition of c-Myc oncogene expression, which may be responsible for the reduced viability of NPC-derived cell lines. In conclusion, our findings provide a strong evidence that three novel EBV LMP2A N-terminal domain-binding affibody molecules have great potential for utilisation and development as agents for both molecular imaging and targeted therapy of EBV-related NPC.

Latent Membrane Protein-1 Protein Induction toward Vascular Endothelial Growth Factor Expression in the Development of Nasopharyngeal Carcinoma

BACKGROUND: Nasopharyngeal carcinoma (NPC) is associated with Epstein–Barr virus infection as the main factor. Latent membrane protein (LMP)-1 protein and vascular endothelial growth factor (VEGF) have been suggested as the prognostic biomarker for NPC.&#x0D; AIM: This study is conducted to analyze the overexpression of LMP-1 protein and VEGF and the combination of these two in NPC patients. The role of LMP-1 protein in the induction of VEGF is identified by analyzing the association between these two proteins.&#x0D; METHODS: A cross-sectional design study is conducted at Adam Malik General Hospital. Formalin-fixed, paraffin-embedded sections from the NPC tissue samples are submitted for immunohistochemistry staining. Fisher’s exact test is used to analyze variables relation.&#x0D; RESULTS: Among 56 samples, there was a significant correlation between LMP-1 protein overexpression with histopathological type and clinical staging, and VEGF overexpression with lymph node enlargement and clinical staging (p &lt; 0.05). There was no significant correlation between LMP-1 protein with VEGF in NPC patients (p &gt; 0.05).&#x0D; CONCLUSION: Increased expressions of LMP-1 protein, VEGF, and a combination of LMP-1 protein and VEGF are noted in correlation with increasing the clinical stages. In contrast to the previously suggested hypotheses, the correlation between these two proteins is not significant in the present study. It could happen due to the different associations of each protein overexpression toward the clinical parameter. However, these two proteins could be used in evaluating the prognosis and providing a targeted therapy to NPC.

Downregulation of HLA-ABC expression through promoter hypermethylation and downmodulation of MIC-A/B surface expression in LMP2A-positive epithelial carcinoma cell lines

Epstein Barr Virus (EBV) is a human herpesvirus, and has been reported to be associated with nasopharyngeal carcinoma, gastric carcinoma, Burkitt’s lymphoma and Hodgkin’s lymphoma. In most of the associated tumors, the virus remains in a latently infected state. During latency, EBV expresses Latent Membrane Protein 2A (LMP2A) along with few other genes. We previously showed that LMP2A causes downregulation of HLA-ABC surface expression in EBV associated gastric carcinomas. However, the mechanism that leads to this downregulation remain unclear. We therefore analyzed methylation-mediated regulation of HLA-ABC expression by LMP2A. Interestingly, according to the ‘missing self’ hypothesis, when there is a decrease in HLA-ABC surface expression, expression of NKG2D ligands’ must be upregulated to facilitate killing by Natural Killer (NK) cells. Analysis of NKG2D ligands’ expression, revealed downregulation of MIC-A/B surface expression in response to LMP2A. Furthermore, the role of Unfolded Protein Response (UPR) in the regulation of MIC-A/B surface expression in cells expressing LMP2A was also investigated. Protein Disulfide Isomerase (PDI) mediated inhibition of MIC-A/B surface expression was observed in LMP2A expressing cells. Our current findings provide new insights in LMP2A arbitrated dysregulation of host immune response in epithelial cell carcinomas.

Epstein-Barr virus-positive gastric cancer involves enhancer activation through activating transcription factor 3.

Epstein‐Barr virus (EBV) is associated with particular forms of gastric cancer (GC). We previously showed that EBV infection into gastric epithelial cells induced aberrant DNA hypermethylation in promoter regions and silencing of tumor suppressor genes. We here undertook integrated analyses of transcriptome and epigenome alteration during EBV infection in gastric cells, to investigate activation of enhancer regions and related transcription factors (TFs) that could contribute to tumorigenesis. Formaldehyde‐assisted isolation of regulatory elements (FAIRE) sequencing (‐seq) data revealed 19 992 open chromatin regions in putative H3K4me1+ H3K4me3− enhancers in EBV‐infected MKN7 cells (MKN7_EB), with 10 260 regions showing increase of H3K27ac. Motif analysis showed candidate TFs, eg activating transcription factor 3 (ATF3), to possibly bind to these activated enhancers. ATF3 was considerably upregulated in MKN7_EB due to EBV factors including EBV‐determined nuclear antigen 1 (EBNA1), EBV‐encoded RNA 1, and latent membrane protein 2A. Expression of mutant EBNA1 decreased copy number of the EBV genome, resulting in relative downregulation of ATF3 expression. Epstein‐Barr virus was also infected into normal gastric epithelial cells, GES1, confirming upregulation of ATF3. Chromatin immunoprecipitation‐seq analysis on ATF3 binding sites and RNA‐seq analysis on ATF3 knocked‐down MKN7_EB revealed 96 genes targeted by ATF3‐activating enhancers, which are related with cancer hallmarks, eg evading growth suppressors. These 96 ATF3 target genes were significantly upregulated in MKN7_EB compared with MKN7 and significantly downregulated when ATF3 was knocked down in EBV‐positive GC cells SNU719 and NCC24. Knockdown of ATF3 in EBV‐infected MKN7, SNU719, and NCC24 cells all led to significant decrease of cellular growth through an increase of apoptotic cells. These indicate that enhancer activation though ATF3 might contribute to tumorigenesis of EBV‐positive GC.

Silymarin Inhibits Proliferation and Induces Apoptosis in Epstein-Barr Virus-Positive Lymphoma Cells by Suppressing Nuclear Factor-Kappa B�Pathway

Epstein Barr virus-positive lymphoma results from the loss of homeostatic balance between Epstein Barr virus and immune cells. In this study, we investigated the mechanism underlying reduction in Epstein Barr virus-positive lymphoma cell proliferation and apoptosis by silymarin, an anti-inflammatory/antioxidant molecule extracted from Silybum�marianum (milk thistle). We examined the effect of silymarin on Raji cell proliferation, apoptosis, the expression of latent membrane protein�1, the proteins related to apoptosis, and the activation of nuclear factor kappa-B. Results showed that silymarin inhibited the proliferation and promoted apoptosis of Raji cells in a concentration-dependent manner. Also, silymarin reduced phosphorylated inhibitor of nuclear factor kappa-B and p65 levels. Silymarin treatment elevated latent membrane protein 1 expression and knockdown of this protein led to increased proliferation inhibition and apoptosis by silymarin. In conclusion, nuclear factor kappa-B and latent membrane protein 1 knockdown could work in concert with silymarin in suppressing Epstein Barr virus-positive lymphoma cell proliferation and inducing apoptosis.

Overexpression of Semaphorin 3A is a Marker Associated with Poor Prognosis in Patients with Nasopharyngeal Carcinoma.

Semaphorins were discovered as guidance signals that mediate neural development. Recent studies suggest that semaphorin 3A (Sema3A), a member of the semaphorin family, is involved in the development of several cancers. This study aimed to analyze the association of Sema3A with the clinical features of nasopharyngeal carcinoma (NPC), an Epstein–Barr virus-associated carcinoma, and the Epstein–Barr virus primary oncogene latent membrane protein 1 (LMP1). The expression of Sema3A and LMP1 was immunohistochemically examined in the 35 NPC specimens. The mean expression scores for Sema3A and LMP1 were 20.8% ± 14.5% and 13.9% ± 14.8%, respectively. The expression of Sema3A significantly correlated with that of LMP1 (r = 0.41, p = 0.014). In addition, the Sema3A high cohort showed significantly poorer prognosis than the Sema3A low cohort. Sema3A expression was higher in the LMP1-positive KH-1 and KR-4 cell lines compared to the LMP1-negative HeLa cells. Overexpression of LMP1 in the LMP1-negative AdAH cell line upregulated Sema3A expression, both at the transcriptional and translational level. Finally, Sema3A expression was associated with poor prognosis in patients with NPC. Our data suggest that LMP1 induces the expression of Sema3A, which may promote tumor progression in NPC.

Extracellular vesicle packaged LMP1-activated fibroblasts promote tumor progression via autophagy and stroma-tumor metabolism coupling.

Several reports have demonstrated that Epstein-Barr virus (EBV) encoded latent membrane protein 1 (LMP1), which is transferred by extracellular vesicles (EVs) or exosomes, can promote cancer progression. However, its mechanism is still not fully understood. In the present study, we demonstrated that EV packaged LMP1 can activate normal fibroblasts (NFs) into cancer-associated fibroblasts (CAFs). The NF-κB p65 pathway is the key signal that promotes the activation of NFs to CAFs in nasopharyngeal carcinoma (NPC). In activated CAFs, aerobic glycolysis and autophagy were increased. Moreover, glucose uptake and lactate production were decreased, and mitochondrial activity in tumor cells was enhanced, which supported the Reverse Warburg Effect (RWE). During this process, upregulation of MCT4 in CAFs and MCT1 in tumor cells was observed. The NF-κB p65 pathway also plays an important role in the regulation of MCT4. Furthermore, co-culture with CAFs promoted the proliferation, migration and radiation resistance of NPC cells. And EV packaged LMP1 promoted tumor proliferation and pre-metastatic niche formation by activating CAFs in vivo. Our findings indicate that EV packaged LMP1-activated CAFs promote tumor progression via autophagy and stroma-tumor metabolism coupling.