Epstein-Barr virus latent membrane protein 2A promotes invasion of nasopharyngeal carcinoma cells through ERK/Fra-1-mediated induction of matrix metalloproteinase 9

War or peace: Viruses and metastasis

Metastasis, the dissemination of malignant cells from a primary tumor to secondary sites, poses a catastrophic burden to cancer treatment and is the predominant cause of mortality in cancer patients. Metastasis as one of the main aspects of cancer progression could be strongly under the influence of viral infections. In fact, viruses have been central to modern cancer research and are associated with a great number of cancer cases. Viral-encoded elements are involved in modulating essential pathways or specific targets that are implicated in different stages of metastasis. Considering the continuous emergence of new viruses and the establishment of their contribution to cancer progression, the warfare between viruses and cancer appears to be endless. Here we aimed to review the critical mechanism and pathways involved in cancer metastasis and the influence of viral machinery and various routes that viruses adopt to manipulate those pathways for their benefit.

Nasopharyngeal carcinoma ecology theory: cancer as multidimensional spatiotemporal "unity of ecology and evolution" pathological ecosystem

Nasopharyngeal carcinoma (NPC) is a particular entity of head neck cancer that is generally regarded as a genetic disease with diverse intertumor and intratumor heterogeneity. This perspective review mainly outlines the up-to-date knowledge of cancer ecology and NPC progression, and presents a number of conceptual stepping-stones. At the beginning, I explicitly advocate that the nature of NPC (cancer) is not a genetic disease but an ecological disease: a multidimensional spatiotemporal "unity of ecology and evolution" pathological ecosystem. The hallmarks of cancer is proposed to act as ecological factors of population fitness. Subsequently, NPC cells are described as invasive species and its metastasis as a multidirectional ecological dispersal. The foundational ecological principles include intraspecific relationship (e.g. communication) and interspecific relationship (e.g. competition, predation, parasitism and mutualism) are interpreted to understand NPC progression. "Mulberry-fish-ponds" model can well illustrate the dynamic reciprocity of cancer ecosystem. Tumor-host interface is the ecological transition zone of cancer, and tumor buddings should be recognized as ecological islands separated from the mainland. It should be noted that tumor-host interface has a significantly molecular and functional edge effect because of its curvature and irregularity. Selection driving factors and ecological therapy including hyperthermia for NPC patients, and future perspectives in such field as "ecological pathology", "multidimensional tumoriecology" are also discussed. I advance that "nothing in cancer evolution or ecology makes sense except in the light of the other". The cancer ecology tree is constructed to comprehensively point out the future research direction. Taken together, the establishment of NPC ecology theory and cancer ecology tree might provide a novel conceptual framework and paradigm for our understanding of cancer complex causal process and potential preventive and therapeutic applications for patients.

When AHR signaling pathways meet viral infections

Aryl hydrocarbon receptor (AHR) is a ligand-dependent transcriptional factor widely expressed among immune, epithelial, endothelial and stromal cells in barrier tissues. It can be activated by small molecules provided by pollutants, microorganisms, food, and metabolism. It has been demonstrated that AHR plays an important role in modulating the response to many microbial pathogens, and the abnormal expression of AHR signaling pathways may disrupt endocrine, cause immunotoxicity, and even lead to the occurrence of cancer. Most humans are infected with at least one known human cancer virus. While the initial infection with these viruses does not cause major disease, the metabolic activity of infected cells changes, thus affecting the activation of oncogenic signaling pathways. In the past few years, lots of studies have shown that viral infections can affect disease progression by regulating the transmission of multiple signaling pathways. This review aims to discuss the potential effects of virus infections on AHR signaling pathways so that we may find a new strategy to minimize the adverse effects of the AHR pathway on diseases. Video Abstract.

The role of Epstein-Barr virus in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a metastasis-prone malignancy closely associated with the Epstein-Barr virus (EBV). Despite ubiquitous infection of EBV worldwide, NPC incidences displayed predominance in certain ethnic groups and endemic regions. The majority of NPC patients are diagnosed with advanced-stage disease, as a result of anatomical isolation and non-specific clinical manifestation. Over the decades, researchers have gained insights into the molecular mechanisms underlying NPC pathogenesis as a result of the interplay of EBV infection with several environmental and genetic factors. EBV-associated biomarkers were also used for mass population screening for the early detection of NPC. EBV and its encoded products also serve as potential targets for the development of therapeutic strategies and tumour-specific drug delivery. This review will discuss the pathogenic role of EBV in NPC and efforts in exploiting the potential of EBV-associated molecules as biomarkers and therapeutic targets. The current knowledge on the role of EBV and its associated products in NPC tumorigenesis, development and progression will offer a new outlook and potential intervention strategy against this EBV-associated malignancy.

EBV promotes vascular mimicry of dormant cancer cells by potentiating stemness and EMT

Vascular mimicry (VM) is defined as a vascular channel-like structure composed of tumor cells that correlates with the growth of cancer cells by providing blood circulation. However, whether VM can be formed in dormant cancer cells remains unclear. Our previous research revealed that polyploid giant cancer cells (PGCCs) are specific dormant cells related to the poor prognosis of head and neck cancer. Here, we demonstrated that EBV could promote VM formation by PGCCs in vivo and in vitro. Furthermore, we revealed that the activation of the ERK pathway partly mediated by LMP2A is responsible for stemness, and the acquisition of the stemness phenotype is crucial to the malignant biological behavior of PGCCs. The epithelial-to-mesenchymal transition (EMT) process plays a considerable role in PGCCs, and EMT progression is vital for EBV-positive PGCCs to form VM. This is the first study to reveal that EBV creates plasticity in PGCC-VM and provide a new strategy for targeted anti-tumor therapy.

Circulating microRNAs as the Potential Diagnostic and Prognostic Biomarkers for Nasopharyngeal Carcinoma

microRNAs are endogenous non-coding miRNAs, 19–25 nucleotides in length, that can be detected in the extracellular environment in stable forms, named circulating miRNAs (CIR-miRNAs). Since the first discovery of CIR-miRNAs, a large number of studies have demonstrated that the abnormal changes in its expression could be used to significantly distinguish nasopharyngeal carcinoma (NPC) from healthy cells. We herein reviewed and highlighted recent advances in the study of CIR-miRNAs in NPC, which pointed out the main components serving as promising and effective biomarkers for NPC diagnosis and prognosis. Furthermore, brief descriptions of its origin and unique characteristics are provided.

The role of Exosomes in the Pathogenesis of Nasopharyngeal Carcinoma and the involved Clinical Application

Exosomes are nanoscale membrane vesicles, which carry biologically active substances of their cell of origin and play an important role in signal transduction and intercellular communication. At present, exosomes have been identified as a promising non-invasive liquid biopsy biomarker in the tissues and circulating blood of nasopharyngeal carcinoma (NPC) and found to participate in regulating pathophysiological process of the tumor. We here review recent insights gained into the molecular mechanisms of exosome-induced cell growth, angiogenesis, metastasis, immunosuppression, radiation resistance and chemotherapy resistance in the development and progression of NPC, as well as the clinical application of exosomes as diagnostic biomarkers and therapeutic agents. We also discuss the limitations and challenges in exosome application. We hope this review may provide some references for the use of exosomes in clinical intervention.

LMP2A suppresses the role of AHR pathway through ERK signal pathway in EBV-associated gastric cancer

OBJECTIVE

To investigate the function of the aryl hydrocarbon receptor (AHR) pathway in Epstein-Barr Virus (EBV)-associated gastric cancer (EBVaGC) and to explore the relationship between EBV and AHR expression.

METHODS

The expression of AHR in EBVaGC and EBV negative GC (EBVnGC) tissues was detected by immunohistochemistry (IHC). Real-time qPCR (RT-qPCR) and Western blot analysis were used to examine the expression of AHR, cytochrome P450 1A1 (CYP1A1), and cytochrome P450 1B1 (CYP1B1) in gastric cancer cells. The cell proliferation and migration assay were tested by CCK8 and transwell analysis. EBV-encoded latent membrane protein 2A (LMP2A) was over-expressed in SGC7901 cells and silenced in AGS-EBV cells to further identify its role in EBV positive GC cells.

RESULTS

It was found that EBV infection inhibited the expression of AHR in gastric cancer tissues and cell lines. We also found that the activation of AHR pathway can promote cell proliferation and migration. However, the function was restricted in EBVaGC cell lines compared with EBVnGC. LMP2A can suppress AHR expression and pathway activation by activating phosphorylation of extracellular signal-regulated kinase (ERK) in EBV positive GC cell lines.

CONCLUSION

EBV-encoded LMP2A regulated the function of the AHR pathway by activating the ERK signal pathway in EBV positive GC cell lines.

Epstein-Barr Virus Facilitates Expression of KLF14 by Regulating the Cooperative Binding of the E2F-Rb-HDAC Complex in Latent Infection

Epstein-Barr virus (EBV) was discovered as the first human tumor virus more than 50 years ago. EBV infects more than 90% of the human population worldwide and is associated with numerous hematologic malignancies and epithelial malignancies. EBV establishes latent infection in B cells, which is the typical program seen in lymphomagenesis. Understanding EBV-mediated transcription regulatory networks is one of the current challenges that will uncover new insights into the mechanism of viral-mediated lymphomagenesis. Here, we describe the regulatory profiles of several cellular factors (E2F6, E2F1, Rb, HDAC1, and HDAC2) together with EBV latent nuclear antigens using next-generation sequencing (NGS) analysis. Our results show that the E2F-Rb-HDAC complex exhibits similar distributions in genomic regions of EBV-positive cells and is associated with oncogenic super-enhancers involving long-range regulatory regions. Furthermore, EBV latent antigens cooperatively hijack this complex to bind at KLFs gene loci and facilitate KLF14 gene expression in lymphoblastoid cell lines (LCLs). These results demonstrate that EBV latent antigens can function as master regulators of this multisubunit repressor complex (E2F-Rb-HDAC) to reverse its suppressive activities and facilitate downstream gene expression that can contribute to viral-induced lymphomagenesis. These results provide novel insights into targets for the development of new therapeutic interventions for treating EBV-associated lymphomas.IMPORTANCE Epstein-Barr virus (EBV), as the first human tumor virus, infects more than 90% of the human population worldwide and is associated with numerous human cancers. Exploring EBV-mediated transcription regulatory networks is critical to understand viral-associated lymphomagenesis. However, the detailed mechanism is not fully explored. Now we describe the regulatory profiles of the E2F-Rb-HDAC complex together with EBV latent antigens, and we found that EBV latent antigens cooperatively facilitate KLF14 expression by antagonizing this multisubunit repressor complex in EBV-positive cells. This provides potential therapeutic targets for the treatment of EBV-associated cancers.

Epstein-Barr Virus Mediated Signaling in Nasopharyngeal Carcinoma Carcinogenesis

Simple Summary

Epstein-Barr virus (EBV) infection is known to contribute in nasopharyngeal carcinoma (NPC) carcinogenesis. The oncogenic roles of the EBV proteins and non-coding RNAs in NPC are becoming evident with the aid of current advances in genome-wide and in-depth molecular analyses. This current work provides a comprehensive overview, which covers recent understandings of the pathogenic role of EBV infection in NPC. Perspectives on molecular mechanisms, which are involved in the pathogenesis of NPC, focusing on the connection between EBV and NPC cells and the corresponding signaling pathways are highlighted. Cancer hallmarks associated with EBV in NPC development are also discussed herein.

Abstract

Nasopharyngeal carcinoma (NPC) is one of the most common tumors occurring in China and Southeast Asia. Etiology of NPC seems to be complex and involves many determinants, one of which is Epstein-Barr virus (EBV) infection. Although evidence demonstrates that EBV infection plays a key role in NPC carcinogenesis, the exact relationship between EBV and dysregulation of signaling pathways in NPC needs to be clarified. This review focuses on the interplay between EBV and NPC cells and the corresponding signaling pathways, which are modulated by EBV oncoproteins and non-coding RNAs. These altered signaling pathways could be critical for the initiation and progression of NPC.

Comparative study of FosPeg® photodynamic effect on nasopharyngeal carcinoma cells in 2D and 3D models

Photodynamic Therapy (PDT) offers an alternative option for the treatment of nasopharyngeal carcinoma (NPC). The utilization of 3-dimensional (3D) culture model might provide better understanding of PDT effects on NPC cells. The aim of this in vitro study was to compare PDT effect on NPC cells using 2D and 3D models. Two 3D culture models were established using liquid overlay method with agarose base (MCL) and hanging drop method (MCS). PDT was carried out using the combination of FosPeg® and 652 nm laser in 3D and conventional 2D models. The effects of 3D culture size and morphology on the uptake and distribution of sensitizer and gene expression were examined. Photocytotoxity, mode of cell death, and protein expression were compared for 2D and 3D models. Regular and irregular NPC spheroids were obtained from MCL and MCS methods, respectively. A significantly down-regulation of LMP1 mRNA were observed in MCL spheroid. The sensitizer uptake in 3D spheroids was half of 2D culture. More sensitizers were required to obtain IC₅₀ in 3D spheroids. Apoptosis, necrosis and autophagosomes were detected in PDT treated 2D and 3D cells. Different protein expression patterns were observed in 2D and 3D models. FosPeg® PDT is effective in killing NPC cells. MCL-derived 3D spheroid model is more suitable for the evaluation of PDT killing mechanisms.

Epstein-Barr Virus-Encoded Products Promote Circulating Tumor Cell Generation: A Novel Mechanism of Nasopharyngeal Carcinoma Metastasis

Epstein–Barr virus (EBV) is a specific tumorigenic factor in the pathogenesis of nasopharyngeal carcinoma (NPC). Viral products encoded by EBV (LMP1, LMP2A, EBNA1, and miRNAs) have been shown to promote NPC metastasis. EBV-encoded oncoproteins and miRNAs have been shown to induce epithelial–mesenchymal transition (EMT) indirectly by inducing EMT transcription factors (EMT-TFs). These EBV-encoded products also promote the expression of EMT-TFs through post-transcriptional regulation. EMT contributes to generation of circulating tumor cells (CTCs) in epithelial cancers. CTCs exhibit stem cell characteristics, including increased invasiveness, enhanced cell intravasation, and improved cell survival in the peripheral system. EBV may contribute NPC metastasis through promoting generation of CTCs. Furthermore, CTC karyotypes are associated with NPC staging, therapeutic sensitivity, and resistance. We summarized studies showing that EBV-encoded virus-proteins and miRNAs promote generation of NPC CTCs, and highlighted the associated mechanism. This synthesis indicated that EBV mediates NPC metastasis through generation of CTCs.

The AP-1 pathway; A key regulator of cellular transformation modulated by oncogenic viruses

Cancer progression is critically associated with modulation of host cell signaling pathways. Activator protein-1 (AP-1) signaling is one such pathway whose deregulation renders the host more susceptible to cancer development. Oncogenic viruses, including hepatitis B virus, hepatitis C virus, human papilloma virus, Epstein-Barr virus, human T-cell lymphotropic virus type 1, and Kaposi's sarcoma-associated herpes virus, are common causes of cancer. This review discusses how these oncoviruses by acting through various aspects of the host cell signaling machinery such as the AP-1 pathway might affect oncoviral tumorigenesis, replication, and pathogenesis. The review also briefly considers how the pathway might be targeted during infections with these oncogenic viruses.

Expression and function of FRA1 protein in tumors

AP-1 is a dimeric complex that is composed of JUN, FOS, ATF and MAF protein families. FOS-related antigen 1 (FRA1) which encoded by FOSL1 gene, belongs to the FOS protein family, and mainly forms an AP-1 complex with the protein of the JUN family to exert an effect. Regulation of FRA1 occurs at levels of transcription and post-translational modification, and phosphorylation is the major post-translational modification. FRA1 is mainly regulated by the mitogen-activated protein kinases signaling pathway and is degraded by ubiquitin-independent proteasomes. FRA1 can affect biological functions, such as tumor proliferation, differentiation, invasion and apoptosis. Studies have demonstrated that FRA1 is abnormally expressed in many tumors and plays a relevant role, but the specific condition varies from the target organs. FRA1 is overexpressed in breast cancer, lung cancer, colorectal cancer, prostate cancer, nasopharyngeal cancer, thyroid cancer and other tumors. However, the expression of FRA1 is decreased in cervical cancer, and the expression of FRA1 in ovarian cancer and oral squamous cell carcinoma is still controversial. In this review, we present a detailed description of the regulatory factors and functions of FRA1, also, the expression of FRA1 in various tumors and its function in relative tumor.

Modulation of Angiogenic Processes by the Human Gammaherpesviruses, Epstein-Barr Virus and Kaposi's Sarcoma-Associated Herpesvirus

Angiogenesis is the biological process by which new blood vessels are formed from pre-existing vessels. It is considered one of the classic hallmarks of cancer, as pathological angiogenesis provides oxygen and essential nutrients to growing tumors. Two of the seven known human oncoviruses, Epstein–Barr virus (EBV) and Kaposi’s sarcoma-associated herpesvirus (KSHV), belong to the Gammaherpesvirinae subfamily. Both viruses are associated with several malignancies including lymphomas, nasopharyngeal carcinomas, and Kaposi’s sarcoma. The viral genomes code for a plethora of viral factors, including proteins and non-coding RNAs, some of which have been shown to deregulate angiogenic pathways and promote tumor growth. In this review, we discuss the ability of both viruses to modulate the pro-angiogenic process.

The regulatory network of nasopharyngeal carcinoma metastasis with a focus on EBV, lncRNAs and miRNAs

Metastasis of nasopharyngeal carcinoma (NPC) remains a main cause of death for NPC patients even though great advances have been made in therapeutic approaches. An in-depth study into the molecular mechanisms of NPC metastasis will help us combat NPC. Epstein-Barr virus (EBV) infection is an evident feature of nonkeratinizing NPC and is strongly associated with tumor metastasis. Recently, long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) have become a hot topic of research due to their epigenetic regulatory roles in NPC metastasis. The EBV products, lncRNAs and miRNAs can target each other and share several common signaling pathways, which form an interconnected, complex molecular regulatory network. In this review, we discuss the features of this regulatory network and summarize the molecular mechanisms of NPC metastasis, focusing on EBV, lncRNAs and miRNAs with updated knowledge.

Methylation status of ORMDL3 regulates cytokine production and p-ERK/MMP9 pathway expression

Orosomucoid like-3 (ORMDL3) has been identified to be associated with the development of asthma according to previous studies. However, the definite role of ORMDL3 in the pathogenesis of asthma remains unclear. In this study, we found ORMDL3 was highly expressed in PBMC specimens from childhood asthma patients. Cytokines production and p-ERK/MMP-9 pathway expression was also increased in childhood asthma patients compared with controls. In addition, ORMDL3 overexpression induced IL-6 and IL-8 release and activated p-ERK/MMP-9 pathway in vitro. Increased ORMDL3 expression was observed after treated with 5-Aza-CdR. 5-Aza-CdR decreased the percentage of the CpG island in the ORMDL3 promoter region and increased its promoter activity. In addition, 5-Aza-CdR significantly increased IL-6 and IL-8 levels in NHBE cells while there was no obvious alteration after knocking down ORMDL3. Knockdown of ORMDL3 also significantly decreased the expression of p-ERK/MMP-9 pathway in the presence or absence of 5-Aza-CdR. In conclusion, our study provided novel evidence for the association between ORMDL3 and asthma-associated cytokines. Moreover, DNA methylation plays an important role in ORMDL3-mediated increased IL-6 and IL-8 levels and p-ERK/MMP-9 pathway expression.

Epstein-Barr virus Rta promotes invasion of bystander tumor cells through paracrine of matrix metalloproteinase 9

Clinical studies suggest a positive association between malignant progression of nasopharyngeal carcinoma (NPC) and Rta, a transcription factor of Epstein-Barr virus (EBV). However, Rta induces cellular senescence in vitro. To provide an underlying mechanism integrating these clues, we adapted a concept of senescence-associated secretory phenotype (SASP), based on which senescent cells facilitate tumor progression through paracrine. First, Rta-expressing NPC cells themselves show reduced invasiveness but promote invasion of Rta-negative tumor cells through secreted factors. Secretion of matrix metalloproteinase 9 (MMP9), an SASP protein, is increased by Rta, which requires the C-terminus of Rta and Rta-induced activation of E2F. Furthermore, the Rta-induced, paracrine-mediated pro-invasive effect is blocked upon knockdown of MMP9 expression or treatment with an MMP9 inhibitor. This study not only indicates that Rta can contribute to NPC progression through paracrine but also supports that MMP9 is a potential therapeutic target to prevent NPC metastasis.

Role of Epstein-Barr Virus in the Pathogenesis of Head and Neck Cancers and Its Potential as an Immunotherapeutic Target

The role of Epstein-Barr virus (EBV) infection in the development and progression of tumor cells has been described in various cancers. Etiologically, EBV is a causative agent in certain variants of head and neck cancers such as nasopharyngeal cancer. Proteins expressed by the EVB genome are involved in invoking and perpetuating the oncogenic properties of the virus. However, these protein products were also identified as important targets for therapeutic research in the past decades, particularly within the context of immunotherapy. The adoptive transfer of EBV-targeted T-cells as well as the development of EBV vaccines has opened newer lines of research to conceptualize novel therapeutic approaches toward the disease. This review addresses the most important aspects of the association of EBV with head and neck cancers from an immunological perspective. It also aims to highlight the current and future prospects of enhanced EBV-targeted immunotherapies.

Activation of c-Jun/JNK signaling predicts poor prognosis in nasopharyngeal carcinoma

A significant proportion of patients with nasopharyngeal carcinoma (NPC) will develop regional relapse or distant metastasis after treatment. This present study evaluated the role of c-Jun/JNK signaling pathways in NPC and its relationship with prognosis. Our study enrolled 122 patients diagnosed with NPC and 136 chronic nasosinusitis patients. Immunohistochemistry was applied to detect positive expression of c-Jun, JNK, p-c-Jun, and p-JNK proteins. Receiver operating characteristic (ROC) curve was then adopted to assess the diagnostic value of c-Jun/JNK signaling pathways for NPC. Activated c-Jun/JNK signaling pathways were observed in NPC patients. Activation of c-Jun/JNK signaling was associated with TNM staging of NPC, as NPC patients with stage III-IV had higher positive expression rates of c-Jun, JNK, p-c-Jun, and p-JNK proteins compared to NPC patients with stage I-II. According to ROC curve results, areas under the curve of c-Jun, JNK, p-c-Jun, and p-JNK protein expression were 0.943, 0.968, 0.963, and 0.938, respectively. The 1-, 3-, and 5-year survival rates and mean survival times of dead patients were lower and shorter in patients with positive expressions of c-Jun, JNK, p-c-Jun, and p-JNK than those with negative expression (all P < 0.05). Overexpression of c-Jun/JNK is associated with development and progression of NPC, indicating that c-Jun/JNK serves as a predictive indicator for early diagnosis and prognosis of NPC.

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.

Caveolin-1 promotes Ewing sarcoma metastasis regulating MMP-9 expression through MAPK/ERK pathway

Ewing sarcoma (ES) is a bone and soft tissue sarcoma affecting mostly children and young adults. Caveolin-1 (CAV1) is a well-known target of EWS/FLI1, the main driver of ES, with an oncogenic role in ES. We have previously described how CAV1 is able to induce metastasis in ES via matrix metalloproteinase-9 (MMP-9). In the present study we showed how CAV1 silencing in ES reduced MEK1/2 and ERK1/2 phosphorylation. Accordingly, chemical inhibition of MEK1/2 resulted in reduction in MMP-9 expression and activity that correlated with reduced migration and invasion. IQ Motif Containing GTPase Activating Protein 1 (IQGAP1) silencing reduced MEK1/2 and ERK1/2 phosphorylation and MMP-9 expression. Furthermore, IQGAP1 silenced cells showed a marked decrease in their migratory and invasive capacity. We demonstrated that CAV1 and IQGAP1 localize in close proximity at the cellular edge, thus IQGAP1 could be the connecting node between CAV1 and MEK/ERK in ES metastatic phenotype. Analysis of the phosphorylation profile of CAV1-silenced cells showed a decrease of p-ribosomal protein S6 (RPS6). RPS6 can be phosphorylated by p90 ribosomal S6 kinases (RSK) proteins. CAV1-silenced cells showed reduced levels of p-RSK1 and treatment with U0126 provoked the same effect. Despite not affecting ERK1/2 and RPS6 phosphorylation status neither MMP-9 expression nor activity, RSK1 silencing resulted in a reduced migratory and invasive capacity in vitro and reduced incidence of metastases in vivo in a novel orthotopic model. The present work provides new insights into CAV1-driven metastatic process in ES unveiling novel key nodes.

Monocyte-derived factors including PLA2G7 induced by macrophage-nasopharyngeal carcinoma cell interaction promote tumor cell invasiveness

The non-keratinizing undifferentiated subtype of nasopharyngeal carcinoma (NPC) is a malignancy characterized by an intimate relationship between neoplastic cells and a non-neoplastic lymphoid component. Tumor-associated macrophages (TAMs) foster tumor progression through production of soluble mediators that support proliferation, angiogenesis, survival and invasion of malignant cells. However, the role of macrophages in the progression of NPC remains poorly understood. This study aims to investigate the functional and phenotypic changes that occur to macrophages in macrophage-NPC cell co-culture systems, and how these changes influence tumor cells. We found that monocytes, including THP-1 cells and primary human monocytes, co-cultured with C666-1 NPC cells upregulate expression of pro-inflammatory cytokines at the early stages, followed by the induction of metastasis-related genes and interferon-stimulated genes at the later stage of coculture, indicating that TAMs are “educated” by NPC cells for cancer progression. Importantly, the induction of these factors from the TAMs was also found to enhance the migratory capabilities of the NPC cells. We have also identified one of these macrophage-derived factor, phospholipase A2 Group 7 (PLA2G7), to be important in regulating tumor cell migration and a novel tumor-promoting factor in NPC. Further studies to characterize the role of PLA2G7 in tumor metastasis may help determine its potential as a therapeutic target in NPC.

Positive associations between upregulated levels of stress-induced phosphoprotein 1 and matrix metalloproteinase-9 in endometriosis/adenomyosis

Stress-induced phosphoprotein-1 (STIP1), an adaptor protein that coordinates the functions of HSP70 and HSP90 in protein folding, has been implicated in the development of human gynecologic malignancies. This case-control study investigates STIP1 serum levels and tissue expression in relation to endometriosis/adenomyosis in Taiwanese population. Female patients with surgically confirmed endometriosis/adenomyosis were compared with women free of endometriosis/adenomyosis. Serum STIP1 levels were measured using an enzyme-linked immunosorbent assay and surgical tissues were analyzed by immunohistochemistry. Both epithelial and stromal cells in surgical tissues of endometriosis and adenomyosis expressed STIP1 and MMP-9. Notably, MMP-9 expression was significantly decreased when STIP1 expression was knocked-down. In vitro experiments revealed that STIP1 was capable of binding to the MMP-9 promoter and enhanced its transcriptional expression. The preoperative serum STIP1 levels of patients with endometriosis/adenomyosis were significantly higher than those of the controls. In brief, our data suggest an association between STIP1 levels and endometriosis/adenomyosis.

Epstein-Barr virus stably confers an invasive phenotype to epithelial cells through reprogramming of the WNT pathway

Epstein-Barr virus (EBV)-associated carcinomas, such as nasopharyngeal carcinoma (NPC), exhibit an undifferentiated and metastatic phenotype. To determine viral contributions involved in the invasive phenotype of EBV-associated carcinomas, EBV-infected human telomerase-immortalized normal oral keratinocytes (NOK) were investigated. EBV-infected NOK were previously shown to undergo epigenetic reprogramming involving CpG island hypermethylation and delayed responsiveness to differentiation. Here, we show that EBV-infected NOK acquired an invasive phenotype that was epigenetically retained after viral loss. The transcription factor lymphoid enhancer factor 1 (LEF1) and the secreted ligand WNT5A, expressed in NPC, were increased in EBV-infected NOK with sustained expression for more than 20 passages after viral loss. Increased LEF1 levels involved four LEF1 variants, and EBV-infected NOK showed a lack of responsiveness to β-catenin activation. Although forced expression of WNT5A and LEF1 enhanced the invasiveness of parental NOK, LEF1 knockdown reversed the invasive phenotype of EBV-infected NOK in the presence of WNT5A. Viral reprogramming of LEF1 and WNT5A was observed several passages after EBV infection, suggesting that LEF1 and WNT5A may provide a selective advantage to virally-infected cells. Our findings suggest that EBV epigenetically reprogrammed epithelial cells with features of basal, wound healing keratinocytes, with LEF1 contributing to the metastatic phenotype of EBV-associated carcinomas.

Epstein-Barr Virus as a Promising Immunotherapeutic Target for Nasopharyngeal Carcinoma Treatment

Epstein-Barr virus (EBV) is a pathogen that infects more than 90% of global human population. EBV primarily targets B-lymphocytes and epithelial cells while some of them infect monocyte/macrophage, T-lymphocytes, and dendritic cells (DCs). EBV infection does not cause death by itself but the infection has been persistently associated with certain type of cancers such as nasopharyngeal carcinoma (NPC), Burkitt's lymphoma (BL), and Hodgkin's lymphoma (HL). Recent findings have shown promise on targeting EBV proteins for cancer therapy by immunotherapeutic approach. Some studies have also shown the success of adopting EBV-based therapeutic vaccines for the prevention of EBV-associated cancer particularly on NPC. In-depth investigations are in progress to refine the current therapeutic and vaccination strategies. In present review, we discuss the highly potential EBV targets for NPC immunotherapy and therapeutic vaccine development as well as addressing the underlying challenges in the process of bringing the therapy and vaccination from the bench to bedside.

ORMDL3 is associated with airway remodeling in asthma via the ERK/MMP-9 pathway

ORMDL sphingolipid biosynthesis regulator 3 (ORMDL3) has been previously implicated in asthma pathogenesis, its effect on airway remodeling remains to be elucidated. The present study examined the expression levels of ORMDL3 in a mouse model of asthma. Mice were divided into three groups: Asthmatic model (n=10), budesonide‑treated (n=10) and a control group (n=8). Asthma was induced by sensitization with ovalbumin (OVA) and aluminum hydroxide on day 1, 7 and 14. Subsequently mice were exposed to OVA three times per week from day 28. In order to investigate the mechanism of airway remodeling 100 µg/kg aerosol budesonide was administered to 6 animals prior to exposure to OVA. The condition of lung tissues was assessed through histology, and the expression levels of ORMDL3, phosphorylated‑extracellular‑signal regulated kinase (p‑ERK) and matrix metallopeptidase‑9 (MMP‑9) were quantified using immunohistochemistry, reverse transcription‑quantitative polymerase chain reaction and western blotting. A severe inflammatory response and airway remodeling were pretreatment with budesonide. Expression levels of ORMDL3, phosphorylated (p)‑ERK and MMP‑9 were significantly greater in the asthma‑model group; however, in the group pretreated with budesonide their expression was reduced. Expression levels of ORMDL3, p‑ERK and MMP‑9 were significantly positively correlated with bronchial wall thickness. ORMDL3 expression was significantly positively correlated with p‑ERK and MMP‑9. Therefore, increased ORMDL3 expression may induce the p‑ERK/MMP‑9 pathway to promote pathological airway remodeling in patients with asthma.

Lentivirus-mediated RNAi knockdown of LMP2A inhibits the growth of the Epstein-Barr-associated gastric carcinoma cell line GT38 in vitro

In this study, lentivirus-mediated RNA interference (RNAi) was applied to inhibit latent membrane protein 2A (LMP2A) gene expression, in order to explore the effects of LMP2A silencing on the growth of an Epstein-Barr virus-associated gastric carcinoma (EBVaGC) cell line in vitro. Lentivirus-mediated RNAi technology was employed to specifically knock down the LMP2A gene in the EBV-positive gastric carcinoma cell line GT38. After infection, reverse transcription-quantitative polymerase chain reaction, western blotting, flow cytometry and colony formation assays were conducted to evaluate the expression of LMP2A and the biological behavior of the GT38 cell line in vitro. The results showed that the expression of the LMP2A gene was clearly downregulated in the infected cells, which indicated that a highly efficient and stable lentivirus vector was successfully constructed. In the GT38 cells in which the expression of LMP2A was downregulated, the proliferation and colony formation of the cells was significantly inhibited. In addition, it was found that the cell cycle of the GT38 cells was arrested in the G0/G1 phase and the apoptosis rate was increased. These results indicate that lentivirus-mediated RNAi knockdown of LMP2A inhibits the growth of the EBVaGC cell line GT38 in vitro, and suggests that LMP2A is a potential target for gene therapy in the treatment of EBVaGC.

Grifolin inhibits tumor cells adhesion and migration via suppressing interplay between PGC1α and Fra-1 / LSF- MMP2 / CD44 axes

Grifolin, a farnesyl phenolic compound isolated from the fresh fruiting bodies of the mushroom Albatrellus confluens, exhibits effective antitumor bioactivity in previous study of our group and other lab. In this study, we observed that grifolin inhibited tumor cells adhesion and migration. Moreover, grifolin reduced reactive oxygen species (ROS) production and caused cellular ATP depletion in high-metastatic tumor cells. PGC1α (Peroxisome proliferator-activated receptor γ, coactivator 1α) encodes a transcriptional co-activator involved in mitochondrial biogenesis and respiration and play a critical role in the maintenance of energy homeostasis. Interestingly, grifolin suppressed the mRNA as well as protein level of PGC1α. We further identified that MMP2 and CD44 expressions were PGC1α inducible. PGC1α can bind with metastatic-associated transcription factors: Fra-1 and LSF and the protein-protein interaction was attenuated by grifolin treatment. Overall, these findings suggest that grifolin decreased ROS generation and intracellular ATP to suppress tumor cell adhesion/migration via impeding the interplay between PGC1α and Fra-1 /LSF-MMP2/CD44 axes. Grifolin may develop as a promising lead compound for antitumor therapies by targeting energy metabolism regulator PGC1α signaling.

Viral Carcinogenesis Beyond Malignant Transformation: EBV in the Progression of Human Cancers

Cancer progression begins when malignant cells colonize adjacent sites, and it is characterized by increasing tumor heterogeneity, invasion and dissemination of cancer cells. Clinically, progression is the most relevant stage in the natural history of cancers. A given virus is usually regarded as oncogenic because of its ability to induce malignant transformation of cells. Nonetheless, oncogenic viruses may also be important for the progression of infection-associated cancers. Recently this hypothesis has been addressed because of studies on the contribution of the Epstein-Barr virus (EBV) to the aggressiveness of nasopharyngeal carcinoma (NPC). Several EBV products modulate cancer progression phenomena, such as the epithelial-mesenchymal transition, cell motility, invasiveness, angiogenesis, and metastasis. In this regard, there are compelling data about the effects of EBV latent membrane proteins (LMPs) and EBV nuclear antigens (EBNAs), as well as nontranslated viral RNAs, such as the EBV-encoded small nonpolyadenylated RNAs (EBERs) and viral microRNAs, notably EBV miR-BARTs. The available data on the mechanisms and players involved in the contribution of EBV infection to the aggressiveness of NPC are discussed in this review. Overall, this conceptual framework may be valuable for the understanding of the contribution of some infectious agents in the progression of cancers.

A Genome Wide Study of Copy Number Variation Associated with Nasopharyngeal Carcinoma in Malaysian Chinese Identifies CNVs at 11q14.3 and 6p21.3 as Candidate Loci

Background

Nasopharyngeal carcinoma (NPC) is a neoplasm of the epithelial lining of the nasopharynx. Despite various reports linking genomic variants to NPC predisposition, very few reports were done on copy number variations (CNV). CNV is an inherent structural variation that has been found to be involved in cancer predisposition.

Methods

A discovery cohort of Malaysian Chinese descent (NPC patients, n = 140; Healthy controls, n = 256) were genotyped using Illumina^® HumanOmniExpress BeadChip. PennCNV and cnvPartition calling algorithms were applied for CNV calling. Taqman CNV assays and digital PCR were used to validate CNV calls and replicate candidate copy number variant region (CNVR) associations in a follow-up Malaysian Chinese (NPC cases, n = 465; and Healthy controls, n = 677) and Malay cohort (NPC cases, n = 114; Healthy controls, n = 124).

Results

Six putative CNVRs overlapping GRM5, MICA/HCP5/HCG26, LILRB3/LILRA6, DPY19L2, RNase3/RNase2 and GOLPH3 genes were jointly identified by PennCNV and cnvPartition. CNVs overlapping GRM5 and MICA/HCP5/HCG26 were subjected to further validation by Taqman CNV assays and digital PCR. Combined analysis in Malaysian Chinese cohort revealed a strong association at CNVR on chromosome 11q14.3 (P_combined = 1.54x10^-5; odds ratio (OR) = 7.27; 95% CI = 2.96–17.88) overlapping GRM5 and a suggestive association at CNVR on chromosome 6p21.3 (P_combined = 1.29x10^-3; OR = 4.21; 95% CI = 1.75–10.11) overlapping MICA/HCP5/HCG26 genes.

Conclusion

Our results demonstrated the association of CNVs towards NPC susceptibility, implicating a possible role of CNVs in NPC development.

Papillomavirus-Associated Tumor Formation Critically Depends on c-Fos Expression Induced by Viral Protein E2 and Bromodomain Protein Brd4

We investigated the mechanism of how the papillomavirus E2 transcription factor can activate promoters through activator protein (AP)1 binding sites. Using an unbiased approach with an inducible cell line expressing the viral transcription factor E2 and transcriptome analysis, we found that E2 induces the expression of the two AP1 components c-Fos and FosB in a Brd4-dependent manner. In vitro RNA interference confirmed that c-Fos is one of the AP1 members driving the expression of viral oncogenes E6/E7. Mutation analysis and in vivo RNA interference identified an essential role for c-Fos/AP1 and also for the bromodomain protein Brd4 for papillomavirus-induced tumorigenesis. Lastly, chromatin immunoprecipitation analysis demonstrated that E2 binds together with Brd4 to a canonical E2 binding site (E2BS) in the promoter of c-Fos, thus activating c-Fos expression. Thus, we identified a novel way how E2 activates the viral oncogene promoter and show that E2 may act as a viral oncogene by direct activation of c-Fos involved in skin tumorigenesis.

Human Papillomaviruses (HPV) are the etiological agents of cervical cancer and of skin cancer in individuals with the inherited disease epidermodysplasia verruciformis (EV). While the role of the viral oncogenes E6/E7 as drivers of tumorigenesis in cervical cancer has been firmly established, the contribution of the early viral genes in skin cancer is less clear. For EV-associated HPV8 and for the skin cancer model system using cottontail rabbit PV, an important role of the viral E2 protein in tumorigenesis was suggested earlier and regulation of cellular genes by E2 through different mechanisms was demonstrated. We show now that the viral E2 and cellular Brd4 act together to induce the cellular gene c-Fos, which as a member of the AP-1 complex, is involved in the regulation of cellular genes and the viral promoter driving the expression of viral oncogenes. As c-Fos has also been shown to be essential for skin cancer, E2 contributes to tumorigenesis via expression of E6/E7 as well as by increasing c-Fos.

IL-6/NOS2 inflammatory signals regulate MMP-9 and MMP-2 activity and disease outcome in nasopharyngeal carcinoma patients

The role of nitric oxide (NO)(·) in the development of the metastatic properties of nasopharyngeal carcinoma (NPC) is not fully understood. Previous studies proposed that interleukin-6 (IL-6) would act as regulator of matrix metalloprotease activation in NPC. Recently, we showed that (NO)(·) was a critical mediator of tumor growth in patients. The aim of this study was to determine the implication of IL-6 in the progression of NPC pathology via metalloprotease (MMP) activation and their possible correlation with (NO)(·) production. We observed a significant increase in IL-6 and nitrite (NO2 (-)) synthesis in patients (n = 17) as well as a strong expression of IL-6 and nitric oxide synthase 2 (NOS2) in the analyzed tumors (n = 8). In patients' plasma, a negative correlation associated IL-6 with circulating nitrites (r = -0.33). A negative correlation associated the H-scores of these signals in the tumors (r = -0.47). In patients' plasma, nitrite synthesis was positively associated with MMP-9 activation (r = 0.45), pro-MMP-2 expression (r = 0.37), and negatively correlated with MMP-2 activation (r = -0.51). High nitrite levels was associated with better recurrence-free survival (RFS) (p = 0.02). Overall, our results suggest that the IL-6/NOS2 inflammatory signals are involved in the regulation of MMP-9- and MMP-2-dependent metastatic activity and that high circulating nitrite levels in NPC patients may constitute a prognostic predictor for survival.

Differential regulation of matrix metalloproteinases in varicella zoster virus-infected human brain vascular adventitial fibroblasts

Upon reactivation, varicella zoster virus (VZV) spreads transaxonally, infects cerebral arteries and causes ischemic or hemorrhagic stroke, as well as aneurysms. The mechanism(s) of VZV-induced aneurysm formation is unknown. However, matrix metalloproteinases (MMPs), which digest extracellular structural proteins in the artery wall, play a role in cerebral and aortic artery aneurysm formation and rupture. Here, we examined the effect of VZV infection on expression of MMP-1, -2, -3, and -9 in primary human brain vascular adventitial fibroblasts (BRAFS). At 6 days post-infection, VZV- and mock-infected BRAFs were analyzed for mRNA levels of MMP-1, -2, -3 and -9 by RT-PCR and for corresponding total intra- and extracellular protein levels by multiplex ELISA. The activity of MMP-1 was also measured in a substrate cleavage assay. Compared to mock-infected BRAFs, MMP-1, MMP-3 and MMP-9 transcripts, cell lysate protein and conditioned supernatant protein were all increased in VZV-infected BRAFs, whereas MMP-2 transcripts, cell lysate protein and conditioned supernatant protein were decreased. MMP-1 from the conditioned supernatant of VZV-infected BRAFs showed increased cleavage activity on an MMP-1-specific substrate compared to mock-infected BRAFs. Differential regulation of MMPs in VZV-infected BRAFs may contribute to aneurysm formation in VZV vasculopathy.

Epstein-Barr virus latent membrane protein 2A mediated activation of Sonic Hedgehog pathway induces HLA class Ia downregulation in gastric cancer cells

One of the immune evasion strategies manifested by malignant cells is the downregulation of the Human Leukocyte Antigen (HLA). HLA Class I (HLA- A, -B, -C) present endogenous peptides including viral and tumor antigens to cytotoxic T lymphocytes for immune mediated destruction. We have found the Epstein Barr Virus (EBV) Latent Membrane Protein 2A (LMP2A) to be responsible for this HLA downregulation in gastric cancer cells. Our results further indicate the Sonic Hedgehog pathway; primarily Gli1 to bring about the LMP2A mediated decrease in HLA expression.

Mitogen- and stress-activated Kinase 1 mediates Epstein-Barr virus latent membrane protein 1-promoted cell transformation in nasopharyngeal carcinoma through its induction of Fra-1 and c-Jun genes

Background

Mitogen- and Stress-Activated Kinase 1 (MSK1) is a nuclear kinase that serves as active link between extracellular signals and the primary response of gene expression. However, the involvement of MSK1 in malignant transformation and cancer development is not well understood. In this study, we aimed to explore the role of MSK1 in Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1)-promoted carcinogenesis of nasopharyngeal carcinoma (NPC).

Methods

The level of MSK1 phosphorylation at Thr581 was detected by the immunohistochemical analysis in NPC tissues and normal nasopharynx tissues, and its correlation with LMP1 was analyzed in NPC tissues and cell lines. Using MSK1 inhibitor H89 or small interfering RNA (siRNA)-MSK1, the effects of MSK1 on LMP1-promoted CNE1 cell proliferation and transformation were evaluated by CCK-8 assay, flow cytometry and focus-forming assay respectively. Furthermore, the regulatory role of MSK1-mediated histone H3 phosphorylation at Ser10 on the promoter activity and expression of Fra-1 or c-Jun was determined by reporter gene assay and western blotting analysis.

Results

Immunohistochemical analysis revealed that the level of MSK1 phosphorylation at Thr581 was significantly higher in the poorly differentiated NPC tissues than that in normal nasopharynx tissues (P < 0.001). Moreover, high level of phosphorylated MSK1 was positively correlated with the expression of LMP1 in NPC tissues (r = 0.393, P = 0.002) and cell lines. MSK1 inhibitor H89 or knockdown of MSK1 by siRNA dramatically suppressed LMP1-promoted CNE1 cell proliferation, which was associated with the induction of cell cycle arrest at G₀/G₁ phase. In addition, the anchorage-independent growth promoted by LMP1 was blocked in MSK1 knockdown cells. When the activity or expression of MSK1 was inhibited, LMP1-induced promoter activities of Fra-1 and c-Jun as well as their protein levels were greatly reduced. It was found that only H3 WT, but not mutant H3 S10A, dramatically increased LMP1 induction of Fra-1 and c-Jun genes compared with mock cells.

Conclusion

Increased MSK1 activity is critically important for LMP1-promoted cell proliferation and transformation in NPC, which may be correlated with its induction of Fra-1 and c-Jun through phosphorylation of histone H3 at Ser10.

Epstein-Barr virus latent membrane protein 2 induces autophagy to promote abnormal acinus formation

Epstein-Barr virus latent membrane protein 2A (LMP2A) induces many characteristics of carcinoma, including transformation, migration, invasion, and impaired differentiation. The MCF10A cell line differentiates to form hollow acini when grown in Matrigel, and expression of LMP2A inhibited differentiation and anoikis induced by loss of matrix attachment. LMP2A-infected cells formed large, lobular structures rather than hollow acini. Autophagy inhibitors impaired this abnormal growth and induced caspase 3 activation and acinus formation. LMP2A also increased autophagosome formation and expression of proteins in the autophagosome pathway. These findings suggest that LMP2A may inhibit anoikis and luminal clearance in acini through induction of autophagy.

Understanding the interplay between host immunity and Epstein-Barr virus in NPC patients

Epstein-Barr virus (EBV) has been used as a paradigm for studying host-virus interactions, not only because of its importance as a human oncogenic virus associated with several malignancies including nasopharyngeal carcinoma (NPC) but also owing to its sophisticated strategies to subvert the host antiviral responses. An understanding of the interplay between EBV and NPC is critical for the development of EBV-targeted immunotherapy. Here, we summarize the current knowledge regarding the host immune responses and EBV immune evasion mechanisms in the context of NPC.

Prognostic Value of Molecular Markers and Implication for Molecular Targeted Therapies in Nasopharyngeal Carcinoma: An Update in an Era of New Targeted Molecules Development

The aim of the study was to evaluate the prognostic significance of molecular biomarkers which could provide information for more accurate prognostication and development of novel therapeutic strategies for nasopharyngeal carcinoma (NPC). NPC is a unique malignant epithelial carcinoma of head and neck region, with an intimate association with the Epstein-Barr virus (EBV). Currently, the prediction of NPC prognosis is mainly based on the clinical TNM staging; however, NPC patients with the same clinical stage often present different clinical outcomes, suggesting that the TNM stage is insufficient to precisely predict the prognosis of this disease. In this review, we give an overview of the prognostic value of molecular markers in NPC and discuss potential strategies of targeted therapies for treatment of NPC. Molecular biomarkers, which play roles in abnormal proliferation signaling pathways (such as Wnt/β-catenin pathway), intracellular mitogenic signal aberration (such as hypoxia-inducible factor (HIF)-1α), receptor-mediated aberrations (such as vascular endothelial growth factor (VEGF)), tumor suppressors (such as p16 and p27 activity), cell cycle aberrations (such as cyclin D1 and cyclin E), cell adhesion aberrations (such as E-cadherin), apoptosis dysregualtion (such as survivin) and centromere aberration (centromere protein H), are prognostic markers for NPC. Plasma EBV DNA concentrations and EBV-encoded latent membrane proteins are also prognostic markers for NPC. Implication of molecular targeted therapies in NPC was discussed. Such therapies could have potential in combination with different cytotoxic agents to combat and eradicate tumor cells. In order to further improve overall survival for patients with loco-regionally advanced NPC, the development of innovative strategies, including prognostic molecular markers and molecular targeted agents is needed.

Epstein-Barr virus LMP2A suppresses MHC class II expression by regulating the B-cell transcription factors E47 and PU.1

Oncogenic Epstein-Barr virus (EBV) uses various approaches to escape host immune responses and persist in B cells. Such persistent infections may provide the opportunity for this virus to initiate tumor formation. Using EBV-immortalized lymphoblastoid cell lines (LCLs) as a model, we found that the expression of major histocompatibility complex (MHC) class II and CD74 in B cells is repressed after EBV infection. Class II transactivator (CIITA) is the master regulator of MHC class II-related genes. As expected, CIITA was downregulated in LCLs. We showed that downregulation of CIITA is caused by EBV latent membrane protein 2A (LMP2A) and driven by the CIITA-PIII promoter. Furthermore, we demonstrated that LMP2A-mediated E47 and PU.1 reduction resulted in CIITA suppression. Mechanistically, the LMP2A immunoreceptor tyrosine-based activation motif was critical for the repression of E47 and PU.1 promoter activity via Syk, Src, and the phosphatidylinositol 3-kinase/Akt pathway. Elimination of LMP2A in LCLs using a shLMP2A approach showed that the expression levels of E47, PU.1, CIITA, MHC class II, and CD74 are reversed. These data indicated that the LMP2A may reduce MHC class II expression through interference with the E47/PU.1-CIITA pathway. Finally, we demonstrated that MHC class II may be detected in tonsils and EBV-negative Hodgkin disease but not in EBV-associated posttransplant lymphoproliferative disease and Hodgkin disease.

Strategies of oncogenic microbes to deal with WW domain-containing oxidoreductase

WW domain-containing oxidoreductase (WWOX) is a well-documented tumor suppressor protein that controls growth, survival, and metastasis of malignant cells. To counteract WWOX's suppressive effects, cancer cells have developed many strategies either to downregulate WWOX expression or to functionally inactivate WWOX. Relatively unknown is, in the context of those cancers associated with certain viruses or bacteria, how the oncogenic pathogens deal with WWOX. Here we review recent studies showing different strategies utilized by three cancer-associated pathogens. Helicobactor pylori reduces WWOX expression through promoter hypermethylation, an epigenetic mechanism also occurring in many other cancer cells. WWOX has a potential to block canonical NF-κB activation and tumorigenesis induced by Tax, an oncoprotein of human T-cell leukemia virus. Tax successfully overcomes the blockage by inhibiting WWOX expression through activation of the non-canonical NF-κB pathway. On the other hand, latent membrane protein 2A of Epstein-Barr virus physically interacts with WWOX and redirects its function to trigger a signaling pathway that upregulates matrix metalloproteinase 9 and cancer cell invasion. These reports may be just "the tip of the iceberg" regarding multiple interactions between WWOX and oncogenic microbes. Further studies in this direction should expand our understanding of infection-driven oncogenesis.

T cells expressing a LMP1-specific chimeric antigen receptor mediate antitumor effects against LMP1-positive nasopharyngeal carcinoma cells in vitro and in vivo

T cells modified with chimeric antigen receptor are an attractive strategy to treat Epstein-Barr virus (EBV) associated malignancies. The EBV latent membrane protein 1 (LMP1) is a 66-KD integral membrane protein encoded by EBV that consists of transmembrane-spanning loops. Previously, we have identified a functional signal chain variable fragment (scFv) that specifically recognizes LMP1 through phage library screening. Here, we constructed a LMP1 specific chimeric antigen receptor containing anti-LMP1 scFv, the CD28 signalling domain, and the CD3ζ chain (HELA/CAR). We tested its functional ability to target LMP1 positive nasopharyngeal carcinoma cells. HELA/CAR cells were efficiently generated using lentivirus vector encoding the LMP1-specific chimeric antigen receptor to infect activated human CD3+ T cells. The HELA/CAR T cells displayed LMP1 specific cytolytic action and produced IFN-γ and IL-2 in response to nasopharyngeal carcinoma cells overexpressing LMP1. To demonstrate in vivo anti-tumor activity, we tested the HELA/CAR T cells in a xenograft model using an LMP1 overexpressing tumor. Intratumoral injection of anti-LMP1 HELA/CAR-T cells significantly reduced tumor growth in vivo. These results show that targeting LMP1 using HELA/CAR cells could represent an alternative therapeutic approach for patients with EBV-positive cancers.

Dinitrosopiperazine-mediated phosphorylated-proteins are involved in nasopharyngeal carcinoma metastasis

N,N'-dinitrosopiperazine (DNP) with organ specificity for nasopharyngeal epithelium, is involved in nasopharyngeal carcinoma (NPC) metastasis, though its mechanism is unclear. To reveal the pathogenesis of DNP-induced metastasis, immunoprecipitation was used to identify DNP-mediated phosphoproteins. DNP-mediated NPC cell line (6-10B) motility and invasion was confirmed. Twenty-six phosphoproteins were increased at least 1.5-fold following DNP exposure. Changes in the expression levels of selected phosphoproteins were verified by Western-blotting analysis. DNP treatment altered the phosphorylation of ezrin (threonine 567), vimentin (serine 55), stathmin (serine 25) and STAT3 (serine 727). Furthermore, it was shown that DNP-dependent metastasis is mediated in part through ezrin at threonine 567, as DNP-mediated metastasis was decreased when threonine 567 of ezrin was mutated. Strikingly, NPC metastatic tumors exhibited a higher expression of phosphorylated-ezrin at threonine 567 than the primary tumors. These findings provide novel insight into DNP-induced NPC metastasis and may contribute to a better understanding of the metastatic mechanisms of NPC tumors.

Matrix metalloproteinase 12 is induced by heterogeneous nuclear ribonucleoprotein K and promotes migration and invasion in nasopharyngeal carcinoma

Background

Overexpression of heterogeneous nuclear ribonucleoprotein K (hnRNP K), a DNA/RNA binding protein, is associated with metastasis in nasopharyngeal carcinoma (NPC). However, the mechanisms underlying hnRNP K-mediated metastasis is unclear. The aim of the present study was to determine the role of matrix metalloproteinase (MMP) in hnRNP K-mediated metastasis in NPC.

Methods

We studied hnRNP K-regulated MMPs by analyzing the expression profiles of MMP family genes in NPC tissues and hnRNP K-knockdown NPC cells using Affymetrix microarray analysis and quantitative RT-PCR. The association of hnRNP K and MMP12 expression in 82 clinically proven NPC cases was determined by immunohistochemical analysis. The hnRNP K-mediated MMP12 regulation was determined by zymography and Western blot, as well as by promoter, DNA pull-down and chromatin immunoprecipitation (ChIP) assays. The functional role of MMP12 in cell migration and invasion was demonstrated by MMP12-knockdown and the treatment of MMP12-specific inhibitor, PF-356231.

Results

MMP12 was overexpressed in NPC tissues, and this high level of expression was significantly correlated with high-level expression of hnRNP K (P = 0.026). The levels of mRNA, protein and enzyme activity of MMP12 were reduced in hnRNP K-knockdown NPC cells. HnRNP K interacting with the region spanning −42 to −33 bp of the transcription start site triggered transcriptional activation of the MMP12 promoter. Furthermore, inhibiting MMP12 by MMP12 knockdown and MMP12-specific inhibitor, PF-356231, significantly reduced the migration and invasion of NPC cells.

Conclusions

Overexpression of MMP12 was significantly correlated with hnRNP K in NPC tissues. HnRNP K can induce MMP12 expression and enzyme activity through activating MMP12 promoter, which promotes cell migration and invasion in NPC cells. In vitro experiments suggest that NPC metastasis with high MMP12 expression may be treated with PF-356231. HnRNP K and MMP12 may be potential therapeutic markers for NPC, but additional validation studies are warranted.

Lentivirus-mediated RNAi knockdown of LMP2A inhibits the growth of nasopharyngeal carcinoma cell line C666-1 in vitro

Latent membrane protein 2A (LMP2A) is found to play a key role in the development of nasopharyngeal carcinoma (NPC). However, the role of LMP2A silencing in the inhibition of cell growth of NPC has not been clarified. In this study, we inhibited LMP2A gene expression by lentivirus-mediated RNAi, to explore the effects of LMP2A silencing on the growth of NPC cell line in vitro. A lentivirus-mediated RNAi technology was employed to specifically knock down the LMP2A gene in NPC cell line C666-1. Quantitative real-time polymerase chain reaction, Western blot, flow cytometry and colony formation assays were performed to evaluate the expression of LMP2A and biological behavior of cell line C666-1 in vitro. We successfully construct a highly efficient and stable lentivirus vector, which efficiently downregulate the expression of LMP2A gene in infected cell line C666-1. Down-regulation of the expression of LMP2A significantly inhibits the proliferation and colony formation of C666-1 cells. In addition, the specific down-regulation of LMP2A arrests cells in G0/G1 phase of cell cycle and increases apoptosis rate. Our findings suggest that lentivirus-mediated RNAi knockdown of LMP2A inhibits the growth of NPC cell line C666-1 in vitro, and LMP2A may be a potential target for gene therapy in treatment of NPC.

The Epstein-Barr virus-encoded microRNA MiR-BART9 promotes tumor metastasis by targeting E-cadherin in nasopharyngeal carcinoma

MicroRNAs (miRNAs) are a family of small RNA molecules that negatively regulate the expression of protein-coding genes and play critical roles in orchestrating diverse cellular processes. This regulatory mechanism is also exploited by viruses to direct their life cycle and evade the host immune system. Epstein-Barr virus (EBV) is an oncogenic virus that is closely associated with multiple human diseases, including nasopharyngeal carcinoma (NPC), which is a highly metastatic type of tumor and is frequently reported in South Asia. Several viral proteins have been found to promote the migration and invasiveness of NPC cells. However, not all tumor tissues express these viral oncoproteins, suggesting that other mechanisms may contribute to the aggressive behavior of NPC tumor cells. A previous sequencing study by our group revealed that the EBV miRNA miR-BART9 was expressed at high levels in all EBV-positive NPC tissues. In the present study, we used gain- and loss-of-function approaches to investigate the effect of miR-BART9 in EBV-negative and EBV-positive NPC cells. We discovered that miR-BART9 promotes the migration and invasiveness of cultured NPC cells. The promigratory activity observed in vitro was manifested as an enhanced metastatic ability in vivo. Computational analysis revealed that miR-BART9 may target E-cadherin, a membrane protein that is pivotal in preserving cell-cell junctions and the epithelial phenotype. Through biochemical assays and functional rescue analysis, we confirmed that miR-BART9 specifically inhibits E-cadherin to induce a mesenchymal-like phenotype and promote the migration of NPC cells. These results indicated that miR-BART9 is a prometastatic viral miRNA and suggested that high levels of miR-BART9 in EBV-positive NPC cells may contribute to the aggressiveness of tumor cells.

MicroRNAs (miRNAs) are a family of small RNA molecules that negatively regulate the expression of protein-coding genes and orchestrate diverse cellular processes. This regulatory mechanism is also exploited by viruses to manage their life cycle and to evade the host immune system. Epstein-Barr virus (EBV) is closely associated with nasopharyngeal carcinoma (NPC), which is a highly metastatic type of tumor. A previous by our group study discovered that the EBV miRNA miR-BART9 is expressed at high levels in all EBV-positive NPC tissues. In the present study, we used gain- and loss-of-function approaches to investigate the function of miR-BART9 in EBV-negative and EBV-positive NPC cells. We showed that miR-BART9 promotes the migration and invasiveness of cultured NPC cells and enhances the metastatic ability of NPC tumors in vivo. Through computational analysis, we discovered that E-cadherin, a membrane protein that is critical for maintaining cell-cell contact and suppressing tumor metastasis, is a potential target for miR-BART9. Through biochemical assays and a functional rescue analysis, we confirmed that miR-BART9 specifically inhibits E-cadherin to enhance the motility of NPC cells. Our results show that miR-BART9 is a prometastatic viral miRNA and suggest that miR-BART9 may contribute to the aggressiveness of EBV-positive NPC tumors.

Ikappa B kinase alpha involvement in the development of nasopharyngeal carcinoma through a NF-κB-independent and ERK-dependent pathway

OBJECTIVES

Ikappa B kinase alpha (IKKα) plays an inhibitory role in the development of epithelial-derived tumors. However, its specific function in the development of nasopharyngeal carcinoma (NPC) remains unknown. In this study we identify the role and mechanism of IKKα in IKKα-mediated NPC development.

MATERIAL AND METHODS

The effect of IKKα on migration, invasion and tumorigenesis of NPC cell lines was determined using in vitro and in vivo studies. SUNE-1-5-8F cells transfected to overexpress IKKα, SUNE-1-6-10B cells with shRNA-mediated knockdown of IKKα, and three NPC cell lines were studied using Western blotting techniques to compare the major molecules in NF-κB pathways. Additionally, the extracellular signal-regulated kinase (ERK) pathway and matrix metalloproteinases (MMPs) in IKKα-regulated NPC and the effect of Epstein-Barr Nuclear Antigen 1 (EBNA1) on IKKα were examined.

RESULTS

IKKα was underexpressed in highly invasive SUNE-1-5-8F cells compared with non-invasive cells (SUNE-1 and SUNE-6-10B). Overexpression of IKKα in SUNE-1-5-8F cells was achieved through transfection and resulted in inhibited migration and invasion in vitro. Furthermore, IKKα inhibited tumorigenesis in mice inoculated with IKKα-transfected NPC cells in vivo. These processes were independent of the conventional effect of IKKα on Nuclear factor κB (NF-κB) pathways. The ERK pathway was involved in IKKα-related NPC inhibition. Phosphorylation of ERK1/2 and subsequent secretion of MMP-9 were inhibited by the ERK inhibitor U0126 and not regulated by overexpressed IKKα. EBNA1 knockdown using small interfering RNA (siRNA) did not alter the expression of IKKα.

CONCLUSION

Increase in IKKα expression suppresses the progression of NPC through a NF-κB-independent and ERK-dependent pathway.

WW domain-containing oxidoreductase is involved in upregulation of matrix metalloproteinase 9 by Epstein-Barr virus latent membrane protein 2A

WW domain-containing oxidoreductase (WOX1) participates in tumor suppression and many other biologic functions, but its molecular and functional interactions with viral proteins remain largely unknown. This study reveals that WOX1 is physically associated with latent membrane protein 2A (LMP2A), an oncoprotein of Epstein-Barr virus. The molecular interaction involves the tyrosine residue 33 of WOX1 and the proline-rich motifs of LMP2A. Interestingly, endogenous WOX1 is required for some LMP2A-triggered, cancer-promoting effects, including activation of extracellular signal-regulated kinase-1/2, upregulation of matrix metalloproteinase 9 (MMP9) and promotion of cell invasion. Upon knockdown of endogenous WOX1, LMP2A-triggered MMP9 induction is restored by exogenous wild-type WOX1, but not by a WOX1 mutant defective in LMP2A binding. These results indicate that, through interaction with LMP2A, WOX1 is involved in MMP9 induction, suggesting a novel role of WOX1 in Epstein-Barr virus-associated cancer progression.