Upregulation of special AT-rich-binding protein 1 by Epstein-Barr virus latent membrane protein 1 in human nasopharyngeal cells and nasopharyngeal cancer

It Takes Two to Tango: A Review of Oncogenic Virus and Host Microbiome Associated Inflammation in Head and Neck Cancer

Simple Summary

Certain viruses, specifically, human papillomavirus (HPV) and Epstein–Barr virus (EBV), have been linked with the development of head and neck cancer. In this study, we review the mechanisms by which (these) viruses lead to cellular transformation and a chronic inflammatory state. Given that the head and neck host a rich microbiome (which itself is intrinsically linked to inflammation), we scrutinize the literature to highlight the interplay between viruses, cellular transformation, inflammation, and the local host microbiome in head and neck cancer.

Abstract

While the two primary risk factors for head and neck squamous cell carcinoma (HNSCC) are alcohol and tobacco, viruses account for an important and significant upward trend in HNSCC incidence. Human papillomavirus (HPV) is the causative agent for a subset of oropharyngeal squamous cell carcinoma (OPSCC)—a cancer that is impacting a rapidly growing group of typically middle-aged non-smoking white males. While HPV is a ubiquitously present (with about 1% of the population having high-risk oral HPV infection at any one time), less than 1% of those infected with high-risk strains develop OPSCC—suggesting that additional cofactors or coinfections may be required. Epstein–Barr virus (EBV) is a similarly ubiquitous virus that is strongly linked to nasopharyngeal carcinoma (NPC). Both of these viruses cause cellular transformation and chronic inflammation. While dysbiosis of the human microbiome has been associated with similar chronic inflammation and the pathogenesis of mucosal diseases (including OPSCC and NPC), a significant knowledge gap remains in understanding the role of bacterial-viral interactions in the initiation, development, and progression of head and neck cancers. In this review, we utilize the known associations of HPV with OPSCC and EBV with NPC to investigate these interactions. We thoroughly review the literature and highlight how perturbations of the pharyngeal microbiome may impact host-microbiome-tumor-viral interactions—leading to tumor growth.

SATB1 as oncogenic driver and potential therapeutic target in head & neck squamous cell carcinoma (HNSCC)

The Special AT-rich sequence binding protein 1 (SATB1) is a genome organizer protein that controls gene expression of numerous genes by regulating chromatin architecture and targeting chromatin-remodeling/-modifying enzymes onto specific chromatin regions. SATB1 is overexpressed in various tumors. In head and neck squamous cell carcinoma (HNSCC), SATB1 upregulation is correlated with TNM classification, metastasis, poor prognosis and reduced overall survival. In this paper, we comprehensively analyze cellular and molecular effects of SATB1 in a large set of primary cell lines from primary HNSCC or metastases, using RNAi-mediated knockdown in vitro and, therapeutically, in tumor xenograft mouse models in vivo. In a series of 15 cell lines, major differences in SATB1 levels are observed. In various 2-D and 3-D assays, growth inhibition upon efficient siRNA-mediated SATB1 knockdown depends on the cell line rather than initial SATB1 levels. Inhibitory effects are found to be based on cell cycle deceleration, apoptosis induction, decreased HER3 and Heregulin A&B expression, and effects on EMT genes. In vivo, systemic treatment of tumor xenograft-bearing mice with siRNAs formulated in polymeric nanoparticles inhibits tumor growth of two HNSCC xenograft models, resulting from therapeutic SATB1 reduction and concomitant decrease of proliferation and induction of apoptosis. In conclusion, SATB1 represents a promising target in HNSCC, affecting crucial cellular processes and molecular pathways.

Cyclin-dependent kinase 1 and survivin as potential therapeutic targets against nasal natural killer/T-cell lymphoma

Nasal natural killer/T-cell lymphoma (NNKTL) is closely associated with Epstein-Barr virus (EBV) and is characterized by poor prognosis, resulting from rapid progression of lesions in the affected organs. Recent data have shown that NNKTL is associated with the aberrant expression of cyclin-dependent kinase 1 (CDK1) and its downstream target survivin, but little is known about the functional roles of CDK1 and survivin in NNKTL. In the current study, we show that knockdown of the EBV-encoded oncoprotein latent membrane protein 1 (LMP1) induces downregulation of CDK1 and survivin in NNKTL cells. Immunohistochemistry detected CDK1 and survivin expression in LMP1-positive cells of NNKTL biopsy specimens. Inhibition of CDK1 and survivin in NNKTL cells with several inhibitors led to a dose-dependent decrease in cell proliferation. In addition, the Sp1 inhibitor mithramycin, which can downregulate both CDK1 and survivin, significantly suppressed the growth of established NNKTL in a murine xenograft model. Our results suggest that LMP1 upregulation of CDK1 and survivin may be essential for NNKTL progression. Furthermore, targeting CDK1 and survivin with Sp1 inhibitors such as mithramycin may be an effective approach to treat NNKTL, which is considered to be a treatment-refractory lymphoma.

C-Terminal Farnesylation of UCH-L1 Plays a Role in Transport of Epstein-Barr Virus Primary Oncoprotein LMP1 to Exosomes

Exosomes are small vesicles that cells secrete into the extracellular space, and there is increasing evidence that they have pivotal roles in cell-to-cell communication in malignancy. It is reported also that EBV-associated malignant cells, including those derived from nasopharyngeal carcinoma (NPC) and B-cell lymphoma, secrete exosomes. These EBV-related exosomes may contain viral products such as latent membrane protein 1 (LMP1) and may contribute to cancer progression. The aim of this study was to investigate the mechanism by which those viral products are loaded in exosomes. In this study, we show for the first time that ubiquitin C-terminal hydrolase-L1 (UCH-L1) and its C-terminal farnesylation, a posttranslational lipid modification, contribute to this mechanism. Our results also suggest that inhibition of UCH-L1 farnesylation is a potential therapeutic target against cancer metastasis and invasion.

Increasing evidence shows that exosomes are key regulators in cancer cell-to-cell communication. Several reports on Epstein-Barr virus (EBV)-related malignancies demonstrate that latent membrane protein 1 (LMP1) secreted by exosomes derived from EBV- or LMP1-positive cells can promote cancer progression and metastasis. However, the mechanism by which LMP1 is loaded into exosomes is still poorly understood. Here, we examined whether the process of LMP1 loading into exosomes is linked to the multifunctional molecule of the ubiquitin system—ubiquitin C-terminal hydrolase-L1 (UCH-L1). For the first time, we demonstrate that LMP1 is physically associated with UCH-L1 and that directing of LMP1 to exosomes is mediated by C-terminal farnesylation of UCH-L1. Additionally, we found that the FTI-277 farnesyltransferase inhibitor reduces motility- and anchorage-independent growth of EBV-positive cells in functional assays. On the basis of our results, we conclude that C-terminal farnesylation of UCH-L1 is one of the key mechanisms by which LMP1 is sorted to exosomes. We hypothesize that inhibition of farnesylation with specific small-molecule inhibitors blocks exosome-mediated transfer of prometastatic molecules such as LMP1 during cancer cell-to-cell communications and thereby impedes the process of cancer invasion.

IMPORTANCE Exosomes are small vesicles that cells secrete into the extracellular space, and there is increasing evidence that they have pivotal roles in cell-to-cell communication in malignancy. It is reported also that EBV-associated malignant cells, including those derived from nasopharyngeal carcinoma (NPC) and B-cell lymphoma, secrete exosomes. These EBV-related exosomes may contain viral products such as latent membrane protein 1 (LMP1) and may contribute to cancer progression. The aim of this study was to investigate the mechanism by which those viral products are loaded in exosomes. In this study, we show for the first time that ubiquitin C-terminal hydrolase-L1 (UCH-L1) and its C-terminal farnesylation, a posttranslational lipid modification, contribute to this mechanism. Our results also suggest that inhibition of UCH-L1 farnesylation is a potential therapeutic target against cancer metastasis and invasion.

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.

The interplay of host genetic factors and Epstein-Barr virus in the development of nasopharyngeal carcinoma

The interplay between host cell genetics and Epstein-Barr virus (EBV) infection contributes to the development of nasopharyngeal carcinoma (NPC). Understanding the host genetic and epigenetic alterations and the influence of EBV on cell signaling and host gene regulation will aid in understanding the molecular pathogenesis of NPC and provide useful biomarkers and targets for diagnosis and therapy. In this review, we provide an update of the oncogenes and tumor suppressor genes associated with NPC, as well as genes associated with NPC risk including those involved in carcinogen detoxification and DNA repair. We also describe the importance of host genetics that govern the human leukocyte antigen (HLA) complex and immune responses, and we describe the impact of EBV infection on host cell signaling changes and epigenetic regulation of gene expression. High-power genomic sequencing approaches are needed to elucidate the genetic basis for inherited susceptibility to NPC and to identify the genes and pathways driving its molecular pathogenesis.

Nicotinamide induces apoptosis of F9 mouse teratocarcinoma stem cells by downregulation of SATB1 expression

The aim of this study was to decide whether nicotinamide (NA) could induce apoptosis of F9 mouse teratocarcinoma stem cells (MF9) by downregulation of special AT-rich sequence binding protein 1 (SATB1) expression. We used different concentrations of NA (0, 1.5, 2, and 2.5 mmol/L) to treat MF9 cells and analyze SATB1 expression by RT-qPCR and Western blotting; in addition, the cell proliferation was detected in a microplate reader with Cell Counting Kit-8 (CCK-8), and the cell cycle and apoptosis were analyzed using flow cytometry. We found that the expression of SATB1 was decreased significantly in NA-treated groups than in the control group, and its expression level was inversely related to the NA concentration. In addition, CCK-8 analysis showed that NA significantly inhibited the proliferation of MF9 cells, and flow cytometry showed that NA blocked MF9 cells to G1 phase and significantly promoted apoptosis in any treated groups. To confirm the results, we constructed small interference RNA (siRNA) targeting at mouse SATB1 and transferred into MF9 cells. The results indicated that the expression of SATB1 in both mRNA and protein levels was significantly decreased after cells transferred with siRNA sequence for 48 h, the proliferation of MF9 cells was significantly inhibited, and most of MF9 cells were blocked at G1 phase, and the apoptosis rate was increased obviously. The results showed that NA could inhibit the proliferation and induce apoptosis of MF9 cells. These findings might be used as an efficient candidate for teratocarcinoma therapy.

SATB1 and 2 in colorectal cancer

The special AT-rich sequence-binding proteins 1 and 2 (SATB1/2) are nuclear matrix associated proteins that are transcription factors involved in chromatin remodeling and gene regulation. Expression of the SATB2 gene is tissue-specific, and the only epithelial cells expressing SATB2 are the glandular cells of the lower gastrointestinal tract where its expression is regulated by microRNA-31 (miR-31) and miR-182. SATB2, along with its homolog SATB1, are thought to be involved in various cancers with their roles in this disease being specific to the type of cancer. Colorectal cancer (CRC) provides the largest association of SATB2 with cancer and the roles of SATB2 are better defined and more studied in CRC than in any other cancer type. SATB1 displays a negative association with SATB2 in CRC. The various studies that have investigated the involvement of SATB1 and 2 in CRC have produced consistent findings. Here, we form four major conclusions regarding the role of these proteins in CRC and their potential clinical value: (i) SATB2 is a sensitive marker to distinguish CRC from other cancer types, (ii) Reduced expression of SATB2 in CRC is associated with poor prognosis, (iii) High levels of SATB1 expression facilitate CRC and are associated with poor prognosis and (iv) Overexpression of miR-31 and -182 in CRC leads to more aggressive cancer. This review will describe several of the key investigations that established these conclusions and highlight results that offer opportunities for future research in the treatment and diagnosis of CRC.

Cancer stem-like cells in Epstein-Barr virus-associated nasopharyngeal carcinoma

Although the Epstein-Barr virus (EBV) has spread to all populations in the world, EBV-associated nasopharyngeal carcinoma (NPC) is prevalent only in South China and Southeast Asia. The role of EBV in the malignant transformation of nasopharyngeal epithelium is the main focus of current researches. Radiotherapy and chemoradiotherapy have been successful in treating early stage NPC, but the recurrence rates remain high. Unfortunately, local relapse and metastasis are commonly unresponsive to conventional treatments. These recurrent and metastatic lesions are believed to arise from residual or surviving cells that have the properties of cancer stem cells. These cancer stem-like cells (CSCs) have the ability to self-renew, differentiate, and sustain propagation. They are also chemo-resistant and can form spheres in anchorage-independent environments. This review summarizes recent researches on the CSCs in EBV-associated NPC, including the findings regarding cell surface markers, stem cell-related transcription factors, and various signaling pathways. In particular, the review focuses on the roles of EBV latent genes [latent membrane protein 1 (LMP1) and latent membrane protein 2A (LMP2A)], cellular microRNAs, and adenosine triphosphate (ATP)-binding cassette chemodrug transporters in contributing to the properties of CSCs, including the epithelial-mesenchymal transition, stem-like transition, and chemo-resistance. Novel therapeutics that enhance the efficacy of radiotherapy and chemoradiotherapy and inhibitors that suppress the properties of CSCs are also discussed.

Multiple effects of the special AT-rich binding protein 1 (SATB1) in colon carcinoma

SATB1 (special AT-rich binding protein 1) is a global chromatin organizer regulating the expression of a large number of genes. Overexpression has been found in various solid tumors and positively correlated with prognostic and clinicopathological properties. In colorectal cancer (CRC), SATB1 overexpression and its correlation with poor differentiation, invasive depth, TNM (tumor, nodes, metastases) stage and prognosis have been demonstrated. However, more detailed studies on the SATB1 functions in CRC are warranted. In this article, we comprehensively analyze the cellular and molecular role of SATB1 in CRC cell lines with different SATB1 expression levels by using RNAi-mediated knockdown. Using siRNAs with different knockdown efficacies, we demonstrate antiproliferative, cell cycle-inhibitory and proapoptotic effects of SATB1 knockdown in a SATB1 gene dose-dependent manner. Tumor growth inhibition is confirmed in vivo in a subcutaneous tumor xenograft mouse model using stable knockdown cells. The in-depth analysis of cellular effects reveals increased activities of caspases-3, -7, -8, -9 and other mediators of apoptotic pathways. Similarly, the analysis of E- and N-cadherin, slug, twist, β-catenin and MMP7 indicates SATB1 effects on epithelial-mesenchymal transition (EMT) and matrix breakdown. Our results also establish SATB1 effects on receptor tyrosine kinases and (proto-)oncogenes such as HER receptors and Pim-1. Taken together, this suggests a more complex molecular interplay between tumor-promoting and possible inhibitory effects in CRC by affecting multiple pathways and molecules involved in proliferation, cell cycle, EMT, invasion and cell survival.

SATB1 overexpression promotes malignant T-cell proliferation in cutaneous CD30+ lymphoproliferative disease by repressing p21

Cutaneous CD30(+) lymphoproliferative disease (CD30(+)LPD), characterized by the presence of CD30(+) anaplastic large T cells, comprises the second most common group of cutaneous T-cell lymphoma (CTCL). However, little is known about the pathobiology of the CD30(+) lymphoma cells, as well as the mechanisms of disease progression. Here we report that Special AT-rich region binding protein 1 (SATB1), a thymocyte specific chromatin organizer, is over-expressed in CD30(+) lymphoma cells in most CD30(+)LPDs, and its expression is upregulated during disease progression. Our findings show that SATB1 silencing in CD30(+)LPD cells leads to G1 cell cycle arrest mediated by p21 activation. Using chromatin immunoprecipitation, luciferase assays, and mutational analysis, we demonstrate that SATB1 directly regulates the transcription of p21 in a p53-independent manner. Moreover, DNA demethylation on a specific CpG-rich region of the SATB1 promoter is associated with the upregulation of SATB1 during disease progression. These experiments define a novel SATB1-p21 pathway in malignant CD30(+) T lymphocytes, which provides novel molecular insights into the pathogenesis of CD30(+)LPDs and possibly leads to new therapies.

Aberrant SATB1 expression is associated with Epstein-Barr virus infection, metastasis and survival in human nasopharyngeal cells and endemic nasopharyngeal carcinoma

Special AT-rich sequence-binding protein 1 (SATB1) has been identified as a key factor in the progression of some cancers, functioning as a global genome organizer and chromatin regulator. We examined the levels of SATB1 mRNA expression in NPC cell lines 5-8F (high metastasis) and 6-10B (low metastasis) and immortalized human nasopharyngeal epithelial cells NP69-SV40T by quantitative real-time PCR. We also examined the protein expression levels of SATB1 in 72 cases of nasopharyngeal carcinoma (NPC) tissues and 30 cases of normal nasopharyngeal (NNP) tissues by immunohistochemistry, and then assessed the correlations between SATB1 expression and clinicopathological factors. The expression level of SATB1 mRNA in 5-8F was much higher than those in 6-10B and NP69-SV40T (P<0.05). The expression level of SATB1 mRNA in 6-10B was higher than in NP69-SV40T, but the difference was not statistically significant (P>0.05). The positive expression rates of SATB1 protein in NPC (38/72, 52.8%) were significantly higher than in NNP (4/30, 13.3%) (P<0.05). SATB1 protein levels in NPC were not associated with gender, age, and T stage (P>0.05), but positively correlated with the titers of EBVCA-IgA, metastasis (N and M stage), recurrence, and survival (P<0.05). Multivariate analysis showed that the overexpression of SATB1 protein is an independent prognostic factor for NPC. The expression levels of SATB1 were obviously upregulated in primary NPC tissues and human NPC cell lines. Therefore, SATB1 may be a valuable predictor in assessing the metastasis, recurrence, and prognosis of NPC.

Silencing SATB1 influences cell invasion, migration, proliferation, and drug resistance in nasopharyngeal carcinoma

Special AT rich sequence binding protein 1 (SATB1) play an important role in many cancers, but the role of SATB1 in nasopharyngeal carcinoma (NPC) is still not full understand. Immunofluorescence staining showed that SATB1 was mainly localized in the nuclei in CNE-2 cell. After successful down-regulation of SABT1 in NPC cell line CNE-2 by shRNA, compared to parental CNE-2 and control shRNA group, the capacity of the proliferation, migration, invasion and drug resistance of CNE-2 cell was reduced, which indicated that SATB1 may be involved in NPC development and progression. SATB1 may be a promising therapeutic target for nasopharyngeal carcinoma.

Silencing SATB1 inhibits the malignant phenotype and increases sensitivity of human osteosarcoma U2OS cells to arsenic trioxide

In a previous study, we found that the global genome organizer Special AT-rich binding protein 1 (SATB1) is highly expressed in mesenchymal-derived human osteosarcoma U2OS cells and that the knock-down of SATB1 results in the inhibition of cell proliferation. The present study was aimed at investigating the effect of silencing SATB1 on cell migration, invasion, apoptosis and resistance to the chemotherapeutic drug arsenic trioxide. Cell migration and invasion were detected by wound-healing assays and trans-well invasion assays, respectively. Cell apoptosis was analyzed by an in situ Cell Death Detection POD Kit, based on terminal deoxynucleotydyl transferase mediated dUTP nick-end labeling (TUNEL) staining and mRNAs were analyzed by real time qRT-PCR. We found that cell migration and invasion were inhibited and that the proportion of apoptotic cells and sensitivities to the chemotherapeutic drug arsenic trioxide were enhanced by knockdown of SATB1 in U2OS cells. Furthermore, mRNA of ABCC1 and ABCG2 were decreased strikingly after SATB1 silencing. It was concluded that the elevated expression of SATB1 in U2OS cells contributes to maintenance of the malignant phenotype and resistance to chemotherapeutic drugs ATO, suggesting that silencing SATB1 in the cells might improve the effects of arsenic trioxides in the treatment of osteosarcoma in which SATB1 is over-expressed and that ABCC1 and ABCG2 were involved in SATB1 mediated resistance of U2OS cells to ATO.

Over-expression of the special AT rich sequence binding protein 1 (SATB1) promotes the progression of nasopharyngeal carcinoma: association with EBV LMP-1 expression

BACKGROUND

Special AT rich sequence binding protein 1 (SATB1) plays a crucial role in the biology of various types of human cancer. However, the role of SATB1 in human nasopharyngeal carcinoma (NPC) remains unknown. In the present study, we sought to investigate the contribution of aberrant SATB1 expression in the progression of NPC and its association with the Epstein Barr virus (EBV)-encoded latent membrane protein 1 (LMP-1).

METHODS

Immunohistochemical analysis was performed to detect SATB1 and LMP-1 protein in clinical samples, and the association of SATB1 protein expression with patient clinicopathological characteristics and LMP-1 expression were analyzed. SATB1 expression profiles were evaluated in well-differentiated NPC cell line CNE1, poorly-differentiated CNE2Z, undifferentiated C666-1 and immortalized nasopharyngeal epithelia NP-69 cells using quantitative RT-PCR, western blotting and fluorescent staining. After inhibition the SATB1 expression by using SATB1 specific small interfering RNA in these cell lines, the change of cell proliferation was investigated by western blotting analysis of PCNA (proliferating cell nuclear antigen) expression and CCK-8 assay, and the cell migration was assessed by Transwell migration assay. Finally, the expressions of SATB1 and PCNA were examined in CNE1 cells that forced LMP-1 expression by fluorescent staining and RT-PCR.

RESULTS

Immunohistochemical analysis revealed that SATB1 protein expression was elevated in NPC tissues compared to benign nasopharyngeal tissues (P = 0.005). Moreover, high levels of SATB1 protein expression were positively correlated with clinical stage (P = 0.025), the status of lymph node metastasis (N classification) (P = 0.018), distant metastasis (M classification) (P = 0.041) and LMP-1 expression status (r = 2.35, P < 0.01) in NPC patients. In vitro experiments demonstrated that an inverse relationship between SATB1 expression and NPC differentiation status, with SATB1 weakly expressed in NP-69 cells and CNE1 cells, and significant increasingly expressed in CNE-2Z and C666-1 cells. Targeted knockdown of SATB1 expression obviously attenuated the proliferation and migration of highly SATB1-expressing CNE2Z and C666-1 cells, but not NP-69 and CNE1 cells. Interestingly, forced LMP-1 expression in CNE1 cells led to a surprisingly increasing SATB1 expression and nuclear location, companying with an up-regulated PCNA expression.

CONCLUSIONS

Our results reveal that EBV LMP-1-mediated over-expression of SATB1 is associated with NPC progression, suggesting SATB1 may represent a promising biomarker and therapeutic target for NPC.

Pathogenic role of Epstein-Barr virus latent membrane protein-1 in the development of nasopharyngeal carcinoma

Undifferentiated nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus-associated malignant tumor. A consistent elevation in EBV antibody titers is a well-established risk factor for the development of NPC. The pathophysiological relationship and molecular mechanisms of EBV-mediated carcinogenesis have not been fully elucidated. While NPC tumors are known to express three EBV-encoded proteins, EBNA1, LMP1, and LMP2, they also express a large number of virus-encoded small RNAs (EBERs) and microRNAs (miRNAs). Among them, LMP1 may be a central player in the development of NPC. LMP1, an EBV-encoded primary oncogene, functions as a viral mimic of the TNFR family member, CD40, and engages in a number of signaling pathways that induce morphological and phenotypic alterations in epithelial cells. LMP1 upregulates EMT, and contributes to the highly metastatic features of NPC. Moreover, LMP1-associated EMT is accompanied by the expression of cancer stem cell (CSC)/cancer progenitor cell (CPC) markers (CD44high/CD24low) and the acquisition of stem cell/progenitor cell-like properties. BART miRNAs, encoded from the BamHI-A region of the viral genome, are the most abundant transcripts. They modulate apoptosis and host innate immune defense mechanisms. Some BART1 miRNAs are considered to negatively regulate LMP1 protein expression. LMP1 is secreted via exosomes, is incorporated into EBV-uninfected cells by endocytosis, and affects the environment surrounding the tumor. Here we reviewed the contribution of EBV gene products to NPC pathogenesis in relation with LMP1.