Elevated expression of ICAM1 (CD54) and minimal expression of LFA3 (CD58) in epstein-barr-virus-positive nasopharyngeal carcinoma cells

Integration of Human and Viral miRNAs in Epstein-Barr Virus-Associated Tumors and Implications for Drug Repurposing

Epstein-Barr virus (EBV) is associated with several tumors, and has substantial relevance for public health. Therapeutics innovation for EBV-related disorders is much needed. In this context, miRNAs are noncoding RNA molecules that play vital roles in EBV infection. miRNA-Seq and RNA-Seq data for EBV-associated clinical samples and cell lines have been generated, but their detailed integrative analyses, and exploitation for drug repurposing against EBV are lacking. Hence, we identified and analyzed the differentially expressed miRNAs (DEmiRs) in EBV-infected cell lines (28) and infected (28) and uninfected human tissue (20) samples using an in-house pipeline. We found significantly enriched host miRNAs like hsa-mir-3651, hsa-mir-1248, and hsa-mir-29c-3p in EBV-infected samples from EBV-associated nasopharyngeal carcinoma and Hodgkin's lymphoma, among others. Furthermore, we also identified significantly enriched novel miRNAs such as hsa-mir-29c-3p, hsa-mir-3651, and hsa-mir-98-3p, which were not previously reported in EBV-related tumors. Differentially expressed mRNAs (DEMs) were identified in EBV-infected cell lines (21) and uninfected human tissue (14) samples. We predicted and selected 1572 DEMs (upregulated) that are targeted by 547 DEmiRs (downregulated). These were further classified into essential (870) and nonessential (702) genes. Moreover, a miRNA-mRNA network was developed for the hub miRNAs. Importantly, we used the DEMs during EBV latent infection types I, II, and III to identify the candidate drugs for repurposing: Glyburide, Levodopa, Nateglinide, and Stiripentol, among others. To the best of our knowledge, this is the first integrative analyses that identified DEmiRs and DEMs as potential therapeutic targets and predicted drugs as potential candidates for repurposing against EBV-related tumors.

Key genes affecting the progression of nasopharyngeal carcinoma identified by RNA-sequencing and bioinformatic analysis

Background: The present work was conducted to screen the potential biomarkers affecting nasopharyngeal carcinoma (NPC) progression through RNA-sequencing (RNA-seq), bioinformatic analysis and functional experiments.

Materials and Methods: Six normal samples and five NPC clinical samples were collected for RNA-seq analysis. The expression levels in both groups were determined through student’s t-test. We identified genes of P < 0.01 as the differentially expressed genes (DEGs). In addition, gene set enrichment analysis (GSEA) was conducted. Afterwards, STRING V10 database was employed to extract protein interactions among the DEGs. Later, we established a protein-protein interaction (PPI) network, and used the Cytoscape software for network visualization. qRT-PCR was conducted to verify hub genes from clinical samples. Then, the function of CXCL10 in cell proliferation, apoptosis, invasion and migration was evaluated.

Results: A total of 2024 DEGs were identified, among which, 1449 were down-regulated and 575 were up-regulated. The PPI was constructed, and the hub genes including Insulin Like Growth Factor 1 (IGF1), C-X-C Motif Chemokine Ligand 10 (CXCL10), Interleukin 13 (IL13), Intercellular Adhesion Molecule 1 (ICAM1), G Protein Subunit Gamma Transducin 1 (GNGT1), Matrix Metallopeptidase 1 (MMP1), Neurexin 1 (NRXN1) and Matrix Metallopeptidase 3 (MMP3) were obtained. The expression levels of CXCL10, IGF1, MMP3, MMP1, ICAM1, and IL-13 were significantly up-regulated in tumor tissues. High expression levels of CXCL10, MMP3 and ICAM1 predicted poor prognosis of NPC patients. CXCL10 silencing suppressed NPC cell proliferation and migration.

Conclusions: CXCL10 may serve as a potential key gene affecting NPC genesis and progression.

Regulation of Epstein-Barr Virus Life Cycle and Cell Proliferation by Histone H3K27 Methyltransferase EZH2 in Akata Cells

Epigenetic modifications play a pivotal role in the expression of the genes of Epstein-Barr virus (EBV). We found that de novo EBV infection of primary B cells caused moderate induction of enhancer of zeste homolog 2 (EZH2), the major histone H3 lysine 27 (K27) methyltransferase. To investigate the role of EZH2, we knocked out the EZH2 gene in EBV-negative Akata cells by the CRISPR/Cas9 system and infected the cells with EBV, followed by selection of EBV-positive cells. During the latent state, growth of EZH2-knockout (KO) cells was significantly slower after infection compared to wild-type controls, despite similar levels of viral gene expression between cell lines. After induction of the lytic cycle by anti-IgG, KO of EZH2 caused notable induction of expression of both latent and lytic viral genes, as well as increases in both viral DNA replication and progeny production. These results demonstrate that EZH2 is crucial for the intricate epigenetic regulation of not only lytic but also latent gene expression in Akata cells.IMPORTANCE The life cycle of EBV is regulated by epigenetic modifications, such as CpG methylation and histone modifications. Here, we found that the expression of EZH2, which encodes a histone H3K27 methyltransferase, was induced by EBV infection; therefore, we generated EZH2-KO cells to investigate the role of EZH2 in EBV-infected Akata B cells. Disruption of EZH2 resulted in increased expression of EBV genes during the lytic phase and, therefore, efficient viral replication and progeny production. Our results shed light on the mechanisms underlying reactivation from an epigenetic point of view and further suggest a role for EZH2 as a form of innate immunity that restricts viral replication in infected cells.

Pathogenic Role of Exosomes in Epstein-Barr Virus (EBV)-Associated Cancers

Exosomes are 40- to 100-nm membrane-bound small vesicles that carry a great variety of cellular cargoes including proteins, DNA, messenger RNAs (mRNAs), and microRNAs (miRNAs). These nanovesicles are detected in various biological fluids such as serum, urine, saliva, and seminal fluids. Exosomes serve as key mediators in intercellular communication by facilitating the transfer and exchange of cellular components from cells to cells. They contain various pathogenic factors whereby their adverse effects have been implicated in multiple viral infections and cancers. Interestingly, accumulating evidences showed that exosomes derived from tumour viruses or oncoviruses, exacerbate virus-associated cancers by remodelling the tumour microenvironment. In this review, we summarize the contributing factors of Epstein-Barr virus (EBV) products-containing exosomes in viral pathogenesis and their potential implications in EBV-driven malignancies. Understanding the biological role of these exosomes in the disease would undoubtedly boost the development of a more comprehensive strategy to combat EBV-associated cancers and to better predict the therapeutic outcomes. Furthermore, we also highlight the potentials and challenges of EBV products-containing exosomes being employed as diagnostic markers and therapeutic targets for EBV-related cancers. Since these aspects are rather underexplored, we attempt to underline interesting areas that warrant further investigations in the future.

Proteomic analysis of exosomes from nasopharyngeal carcinoma cell identifies intercellular transfer of angiogenic proteins

Exosomes, a group of secreted extracellular nanovesicles containing genetic materials and signaling molecules, play a critical role in intercellular communication. During tumorigenesis, exosomes have been demonstrated to promote tumor angiogenesis and metastasis while their biological functions in nasopharyngeal carcinoma (NPC) are poorly understood. In this study, we focused on the role of NPC-derived exosomes on angiogenesis. Exosomes derived from the NPC C666-1 cells and immortalized nasopharyngeal epithelial cells (NP69 and NP460) were isolated using ultracentrifugation. The molecular profile and biophysical characteristics of exosomes were verified by Western blotting, sucrose density gradient and electron microscopy. We showed that the C666-1 exosomes (10 and 20 μg/ml) could significantly increase the tubulogenesis, migration and invasion of human umbilical vein endothelial cells (HUVECs) in a dose-dependent manner. Subsequently, an iTRAQ-based quantitative proteomics was used to identify the differentially expressed proteins in C666-1 exosomes. Among the 640 identified proteins, 51 and 89 proteins were considered as up- and down-regulated (≥ 1.5-fold variations) in C666-1 exosomes compared to the normal counterparts, respectively. As expected, pro-angiogenic proteins including intercellular adhesion molecule-1 (ICAM-1) and CD44 variant isoform 5 (CD44v5) are among the up-regulated proteins, whereas angio-suppressive protein, thrombospondin-1 (TSP-1) was down-regulated in C666-1 exosomes. Further confocal microscopic study and Western blotting clearly demonstrated that the alteration of ICAM-1 and TSP-1 expressions in recipient HUVECs are due to internalization of exosomes. Taken together, these data strongly indicated the critical roles of identified angiogenic proteins in the involvement of exosomes-induced angiogenesis, which could potentially be developed as therapeutic targets in future.

Exosomes derived from Epstein-Barr virus-infected cells are internalized via caveola-dependent endocytosis and promote phenotypic modulation in target cells

Epstein-Barr virus (EBV), a human gammaherpesvirus, establishes a lifelong latent infection in B lymphocytes and epithelial cells following primary infection. Several lines of evidence suggest that exosomes derived from EBV-infected cells are internalized and transfer viral factors, including EBV-encoded latent membrane protein and microRNAs, to the recipient cells. However, the detailed mechanism by which exosomes are internalized and their physiological impact on the recipient cells are still poorly understood. In this study, we visualized the internalization of fluorescently labeled exosomes derived from EBV-uninfected and EBV-infected B cells of type I and type III latency into EBV-negative epithelial cells. In this way, we demonstrated that exosomes derived from all three cell types were internalized into the target cells in a similar fashion. Internalization of exosomes was significantly suppressed by treatment with an inhibitor of dynamin and also by the knockdown of caveolin-1. Labeled exosomes were colocalized with caveolae and subsequently trafficked through endocytic pathways. Moreover, we observed that exosomes derived from type III latency cells upregulated proliferation and expression of intercellular adhesion molecule 1 (ICAM-1) in the recipient cells more significantly than did those derived from EBV-negative and type I latency cells. We also identified the EBV latent membrane protein 1 (LMP1) gene as responsible for induction of ICAM-1 expression. Taken together, our data indicate that exosomes released from EBV-infected B cells are internalized via caveola-dependent endocytosis, which, in turn, contributes to phenotypic changes in the recipient cells through transferring one or more viral factors.

Features distinguishing Epstein-Barr virus infections of epithelial cells and B cells: viral genome expression, genome maintenance, and genome amplification

Epstein-Barr virus (EBV) is associated with malignant diseases of lymphoid and epithelial cell origin. The tropism of EBV is due to B-cell-restricted expression of CD21, the major receptor molecule for the virus. However, efficient infection of CD21- epithelial cells can be achieved via transfer from EBV-coated B cells. We compare and contrast here the early events following in vitro infection of primary B cells and epithelial cells. Using sensitive, quantitative reverse transcription-PCR assays for several latent and lytic transcripts and two-color immunofluorescence staining to analyze expression at the single cell level, we confirmed and extended previous reports indicating that the two cell types support different patterns of transcription. Furthermore, whereas infection of B cells with one or two copies of EBV resulted in rapid amplification of the viral genome to >20 copies per cell, such amplification was not normally observed after infection of primary epithelial cells or undifferentiated epithelial lines. In epithelial cells, EBNA1 expression was detected in only ca. 40% of EBER+ cells, and the EBV genome was subsequently lost during prolonged culture. One exception was that infection of AGS, a gastric carcinoma line, resulted in maintenance of EBNA1 expression and amplification of the EBV episome. In contrast to B cells, where amplification of the EBV episome occurred even with a replication-defective BZLF1-knockout virus, amplification in AGS cells was dependent upon early lytic cycle gene expression. These data highlight the influence of the host cell on the outcome of EBV infection with regard to genome expression, amplification, and maintenance.

Recurrent overexpression of c-IAP2 in EBV-associated nasopharyngeal carcinomas: critical role in resistance to Toll-like receptor 3-mediated apoptosis

The oncogenic process leading to nasopharyngeal carcinoma (NPC) requires the combination of genetic and epigenetic alterations, latent infection by the Epstein-Barr virus and local inflammation. A transcriptome analysis of NPC xenografts identified the gene encoding the cellular inhibitor of apoptosis protein 2 (c-IAP2) among the top five most intensely expressed. Consistently, the very high levels of the c-IAP2 protein were detected in 11 of 13 NPC biopsies. RMT 5265, a structural analog of second mitochondria-derived activator of caspase (SMAC), induced the rapid degradation of c-IAP2 in nasopharyngeal epithelial cells, whether malignant or not, but blocked clonal cell growth in NPC cells only. In short-term experiments, RMT 5265 induced apoptosis in a fraction of NPC cells, and this apoptosis was dramatically enhanced when RMT 5265 was combined with Toll-like receptor 3 (TLR3) stimulation. By contrast, the cooperative effect with tumor necrosis factor alpha was only marginal. The apoptosis induced by the combination of RMT 5265 and TLR3 stimulation was mediated by caspase-8 and associated with a decrease in the cellular content of the long isoform of FLICE-like inhibitory protein. Similar caspase-8 activation was obtained when siRNA knockdown of c-IAP2 was combined with TLR3 stimulation. In conclusion, c-IAP2 has a specific protective function in NPC cells challenged by TLR3 agonists. This protective function is probably important to make NPC cells tolerant to their own production of small viral RNAs, which are potential agonists of TLR3. Our data will help to design a rational use of IAP inhibitors in NPC patients.

The role of Epstein-Barr virus in cancer

Epstein-Barr virus (EBV), discovered > 40 years ago from a Burkitt's lymphoma biopsy, was the first virus to be directly associated with human cancer. EBV has two distinct life cycles in the human host; a lytic form of infection that produces new infectious virions, and a latent form of infection that allows the virus to persist in a dormant state for the lifetime of the host. EBV has evolved a life cycle that mimics the natural differentiation pathway of antigen-activated B cells, giving the virus access to its site of latent infection, the resting memory B cell. By steering infected cells through the various stages of lymphocyte differentiation, EBV is able to enter a cell type suitable for long-term latent persistence and periodic reactivation. However, its presence in various stages of B-cell development, and its ability to infect certain epithelial cells, can have pathogenic consequences, and can contribute to the development of a diverse group of lymphomas and carcinomas. The presence of EBV in the tumour cells of EBV-associated cancers might provide a basis for specific therapy. This article focuses on the contributions that the virus may play in different types of human cancer, particularly Burkitt's lymphoma, Hodgkin's lymphoma, lymphomas and lymphoproliferative diseases in the immunocompromised, and nasopharyngeal and gastric carcinoma.

Hypericin-mediated photodynamic therapy elicits differential interleukin-6 response in nasopharyngeal cancer

Cytokines induce inflammatory and immune responses in tumors after photodynamic therapy (PDT). Since there are no reports of IL-6 in nasopharyngeal cancer (NPC) cells following PDT, we evaluated IL-6 expression in two different NPC tumors after hypericin mediated PDT. Interleukin-6 transcription was significantly upregulated in PDT-treated CNE-2 poorly differentiated cells but not in HK1 well differentiated cells. In vivo, IL-6 mRNA expression was elevated in PDT-treated CNE-2 tumors but not in HK1 tumors. In conclusion, the study elucidated that the cell type, degree of histological differentiation and the basal expression of the cytokine influence the cytokine response following PDT.

Nasopharyngeal carcinoma-susceptibility locus is localized to a 132 kb segment containing HLA-A using high-resolution microsatellite mapping

Nasopharyngeal carcinoma (NPC) is an epithelial tumor uniquely prevalent in southern Chinese. HLA-A2 is associated with NPC. In a previous study, we showed that the genes associated with susceptibility to NPC are primarily located within the HLA-A locus in Taiwanese NPC patients. However, the pathogenic genes causing NPC susceptibility remain unknown. Here, 8 polymorphic microsatellite markers distributed over a 1 megabase region surrounding the HLA-A locus were subjected to genetic analysis for the NPC-susceptibility locus. Statistical studies of associated alleles detected on each microsatellite locus showed that the NPC- susceptibility genes are most likely located between the D6S510 and D6S211 markers within a 132 kb segment containing the HLA-A locus. These results undoubtedly would facilitate the further positional cloning of the NPC-susceptibility locus, which has been elusive for the past 30 years.

Genetic susceptibility to nasopharyngeal carcinoma within the HLA-A locus in Taiwanese

NPC is an epithelial tumor that is highly prevalent among the southern Chinese. Numerous studies have indicated that specific HLA haplotypes and genes within the HLA complex are associated with NPC. As a first effort to localize the gene responsible for susceptibility, the HLA-A, -B, and -A2 subtypes were examined for their association to NPC. Consistent with previous reports, frequencies of HLA-A2 [OR = 2.50, pc = 0.020 (study population); OR = 3.73, pc = 0.0030 (> or =40 years old)] were significantly higher in patients with NPC than in healthy controls. Two-locus analysis indicated that A2(+)B46(+) individuals are at greater risk for NPC than A2(-)B46(-) individuals in both the population studied and the > or =40-year-old group. This, however, may be due to the close linkage of these 2 genes. Moreover, A2(+)B38(+) individuals were at higher risk than A2(-)B38(-) individuals in both the population studied and the > or =40-year-old group; A2 and B38 are not genetically linked. These findings suggest that B38 or B46 alone cannot confer a high risk of NPC but that, in conjunction with A2, B38 or B46 positivity greatly increases risk. None of 5 A2 subtypes identified from studied populations was significantly associated with NPC. Microsatellite marker D6S211, located 97 kb telomeric to HLA-A, was analyzed for its association with NPC. Allele 4 of D6S211 was significantly associated with NPC (OR = 3.97, pc = 0.0042). These results strongly support the hypothesis that genes associated with susceptibility to NPC in the HLA region are within the HLA-A locus.

Nasopharyngeal carcinoma and the EBV-specific T cell response: prospects for immunotherapy

T cells specific for Epstein-Barr virus (EBV) can effectively target the virus-transformed B lymphoproliferative lesions that arise in immunosuppressed transplant patients. This review explores the possibility of developing similar T cell-based strategies to treat an EBV-positive epithelial tumour, nasopharyngeal carcinoma (NPC), which arises in relatively immunocompetent individuals and where EBV antigen expression in the tumour is more limited.

Hypomethylation and hypermethylation of DNA in Wilms tumors

We quantitatively analysed hypermethylation at CpG islands in the 5' ends of 12 genes and one non-CpG island 5' region (MTHFR) in 31 Wilms tumors. We also determined their global genomic 5-methylcytosine content. Compared with various normal postnatal tissues, approximately 40-90% of these pediatric kidney cancers were hypermethylated in four of the genes, MCJ, RASSF1A, TNFRSF12 and CALCA as determined by a quantitative bisulfite-based assay (MethyLight). Interestingly, the non-CpG island 5' region of MTHFR was less methylated in most tumors relative to the normal tissues. By chromatographic analysis of DNA digested to deoxynucleosides, about 60% of the Wilms tumors were found to be deficient in their overall levels of DNA methylation. We also analysed expression of the three known functional DNA methyltransferase genes. No relationship was observed between global genomic 5-methylcytosine levels and relative amounts of RNA for DNA methyltransferases DNMT1, DNMT3A, and DNMT3B. Importantly, no association was seen between CpG island hypermethylation and global DNA hypomethylation in these cancers. Therefore, the overall genomic hypomethylation frequently observed in cancers is probably not just a response or a prelude to hypermethylation elsewhere in the genome. This suggests that the DNA hypomethylation contributes independently to oncogenesis or tumor progression.

Lymphoid cell infiltration into Epstein-Barr virus-positive nasopharyngeal carcinomas

OBJECTIVES

A pilot study was designed to analyze lymphoid cell infiltration in Epstein-Barr virus-positive (EBV+) nasopharyngeal carcinomas (NPCs) and to determine whether this pattern of infiltration is consistent with non-EBV+ head and neck carcinomas or with solid EBV+ tumors in other locations.

STUDY DESIGN

We performed a retrospective analysis of archived NPCs and oral cavity carcinomas.

METHODS

Immunohistochemical staining of the archive material for various markers (CD3, CD8, UCHL-1, S-100, and intercellular adhesion molecule) was performed. Polymerase chain reaction techniques to establish the presence of the EBV genome were used. Cells in different locations were counted under a light microscope by 2 of the authors.

RESULTS

The infiltration pattern of NPCs was different from that of oral cavity carcinomas. Stromal infiltration was significantly denser in oral cavity carcinomas. Tumor nest infiltration was more pronounced in NPCs. The pattern of infiltration was comparable with what has been described for other solid EBV+ tumors.

CONCLUSIONS

The immune response to NPCs is likely to be strongly influenced by the presence of the EBV genome. The pattern of infiltration is similar to that of other non-head and neck EBV+ solid tumors and different from that of EBV- head and neck carcinomas.

Hairy leukoplakia: an unusual combination of transforming and permissive Epstein-Barr virus infections

Human herpesviruses are characterized by distinct states of infection. Typically in permissive herpesvirus infection, abundant virus production results in cell lysis. In latent transforming Epstein-Barr virus (EBV) infection, viral proteins that induce cell growth are expressed. The immunodeficiency-associated hairy leukoplakia (HLP) lesion is the only pathologic manifestation of permissive EBV infection; however, within HLP, viral proteins characteristic of latent infection have also been detected. In this study, we further analyzed expression of EBV latent genes and investigated their contribution to the unique histologic phenotype of HLP. Coexpression of lytic and transforming viral proteins was detected simultaneously within individual HLP keratinocytes. LMP1 has now been shown to be uniformly expressed in the affected tissue, and it is associated and colocalizes with tumor necrosis factor receptor-associated factor (TRAF) signaling molecules. Effects induced by activated TRAF signaling that were detected in HLP included activation of NF-kappaB and c-Jun terminal kinase 1 (JNK1) and upregulated expression of epidermal growth factor receptor (EGFR), CD40, A20, and TRAFs. This study identifies a novel state of EBV infection with concurrent expression of replicative and transforming proteins. It is probable that both replicative and latent proteins contribute to HLP development and induce many of the histologic features of HLP, such as acanthosis and hyperproliferation. In contrast to other permissive herpesvirus infections, expression of EBV transforming proteins within the permissively infected HLP tissue enables epithelial cell survival and may enhance viral replication.

Expression of Epstein-Barr virus latent membrane proteins leads to changes in keratinocyte cell adhesion

Epstein-Barr virus (EBV) has 3 latent membrane proteins (LMPs)--LMP1, LMP2a, and LMP2b--which are expressed in nasopharyngeal carcinoma. Using keratinocyte cell lines expressing LMP2a and LMP2b and coexpressing LMP1/LMP2a, we grew organotypic raft cultures to analyze changes in morphology and expression of the cell adhesion molecule ICAM-1; alpha2, alpha3, alpha5, beta1, and alpha6beta4 integrins; laminin 5; E-cadherin; and desmoplakin. Cells expressing LMP2a or LMP2b were defective in their ability to mature and progress through normal squamous stratification when compared to the parental cell lines. Cells coexpressing LMP1/LMP2a additionally demonstrated "pseudoinvasion" into the raft dermal equivalent. There was a consistent and dramatic up-regulation in the suprabasal expression of laminin 5 and alpha6beta4 and beta1 integrins in the LMP-expressing cell lines. ICAM-1, not expressed in the control cell lines, was up-regulated in the LMP-expressing cell lines. Expression of alpha3 and alpha5 integrins was also up-regulated in the LMP-expressing cell lines, while alpha2 demonstrated a loss of the normal basal layer expression. E-cadherin and desmoplakin expression patterns were essentially unchanged. We conclude that LMP2a and LMP2b singly, and LMP1/LMP2a coexpressed, are capable of altering keratinocyte cell adhesion molecule expression consistent with nasopharyngeal carcinoma.

Gene Structure, Promoter Characterization, and Basis for Alternative mRNA Splicing of the Human CD58 Gene

The 60-kDa lymphocyte function-associated Ag-3 (LFA-3/CD58), a highly glycosylated adhesion molecule that serves as ligand for the T cell-restricted glycoprotein CD2, is encoded by a gene at the human chromosome locus 1p13. We have elucidated the exon-intron organization of the entire human CD58 gene, including ∼2.5 kilobases (kb) of 5′-flanking DNA. Four overlapping genomic clones, spanning ∼65 kb, contained the entire ∼1-kb coding sequence of CD58 and consisted of six separate exons, which varied from 72 to 294 bp in size. At least two different CD58 mRNA precursors can be generated from the human gene as a result of alternative choice of one of the two acceptor splice sites located within exon 5. DNA sequence analysis of about 2.5 kb of 5′-flanking sequence of the CD58 gene indicated the absence of a CAAT box. However, potential binding sites for the transcriptional activators AP-2, GATA, PU.1, and Sp-1 are present. Two consensus TATAA elements, located ∼2.4 kb upstream of the transcriptional start site, have been identified. The 2.5-kb CD58 promoter sequence displayed functional activity in transient transfection assays in the hepatocellular carcinoma cell line HepG2. Comparing the response of CD58 promoter-driven luciferase plasmids to several cytokines and other agents suggests that the CD58 promoter is regulated by up-regulatory, enhancer-like and down-regulatory, silencer-like elements. Further analysis of this region should allow researchers to gain insight into the molecular mechanisms by which this gene is regulated, e.g., during inflammatory responses.

Spontaneous establishment of an Epstein-Barr virus-infected fibroblast line from the synovial tissue of a rheumatoid arthritis patient

An Epstein-Barr virus (EBV)-infected fibroblast line, designated DSEK, was spontaneously established from synovial tissue of a patient with rheumatoid arthritis (RA). DSEK cells expressed EBV nuclear antigens EBNA-1 and EBNA-2 and latent membrane protein LMP-1. Cell surface markers of DSEK cells were similar to those of EBV-negative fibroblast clones derived from synoviocytes and were negative for lymphocyte and macrophage markers. DSEK cells expressed CD44, CD58, and HLA-DR antigens and spontaneously produced interleukin-10 basic fibroblast growth factor and transforming growth factor beta1. These results indicate that rheumatoid synoviocytes can be a target for EBV infection and suggest that EBV may play a role in the pathogenesis of RA.

Molecular regulation of intercellular adhesion molecule 1 (ICAM-1) expression in renal cell carcinoma

Intercellular adhesion molecule-1 (ICAM-1) mediates two important functional aspects of tumor biology, namely enhancement of tumor metastasis and mediation of host defense mechanisms such as lymphocyte-mediated tumor cytotoxicity. Since ICAM-1 is expressed by most renal cell carcinomas (RCC), the regulation of ICAM-1 expression is important in understanding the biological behavior of RCC. We report an investigation on ICAM-1 expression and molecular regulation by cytokines and protein kinase C activator on RCC cell lines. Of the various cytokines, tumor necrosis factor alpha (TNF alpha), interferon-gamma (IFN gamma), and phorbol myristate acetate (PMA) strongly upregulated ICAM-1 protein expression on RCC. The kinetics of ICAM-1 message induction was studied by Northern analysis of total RNA extracted from RCC and normal kidney proximal tubular (NKPT) cells. Time course studies showed that ICAM-1 mRNA was upregulated by INF gamma, TNF alpha, and PMA, plateaued after 2 h, and remained increased for up to 24 h. Although ICAM-1 mRNA in NKPT cells was upregulated by these cytokines, their messages returned to basal levels after 24 h. ICAM-1 mRNA stability assays showed that both unstimulated and stimulated RCC cells had very stable ICAM-1 mRNA up to 24 h. In order to investigate whether increased gene transcription contributes to ICAM-1 upregulation, RCC cells were treated with TNF alpha, IFN gamma, or PMA with or without simultaneous addition of actinomycin D. ICAM-1 message induction-blocking studies suggested that primary upregulation of ICAM-1 mRNA may be caused by transcriptional upregulation. These results suggest that long-lasting ICAM-1 message upregulation in response to cytokines or PMA may be due to transcriptional upregulation in the early phase and stabilization of ICAM-1 message in the later phase (after 4 h). These observations suggest that RCC may lack the normal downregulatory mechanisms which control ICAM-1 expression and may explain the high frequency of ICAM-1 expression observed on primary human RCC.

Human cytotoxic T lymphocyte responses to Epstein-Barr virus infection

Epstein-Barr virus (EBV) provides one of the most informative systems with which to study cytotoxic T lymphocyte (CTL) responses in humans. The virus establishes a highly immunogenic growth-transforming infection of B lymphocytes, associated with the coordinate expression of six virus-coded nuclear antigens (EBNAs 1, 2, 3A, 3B, 3C, -LP) and two latent membrane proteins (LMPs 1 and 2). This elicits both primary and memory CT8+ CTL responses that are markedly skewed toward HLA allele-specific epitopes drawn from the EBNA3A, 3B, 3C subset of latent proteins, with reactivities to other antigens being generally much less frequent. This hierarchy of immunodominance among the different latent proteins may at least partly reflect their differential accessibility to the HLA class I-processing pathway. Furthermore, CTLs to some of the immunodominant epitopes involve highly conserved T cell receptor (TCR) usage, a level of focusing which evidence suggests could have immunopathological consequences from cross-reactive recognition of other target structures. EBV is associated with a range of human tumors, and there is increasing interest in the possibility of targeting such malignancies using virus-specific CTLs. The dramatic reversal of EBV-driven lymphoproliferations in bone marrow transplant patients following CTL infusion demonstrates the potential of this approach, and here we discuss prospects for its extension to other EBV-positive tumors in which the immunodominant EBNA3A, 3B, 3C proteins are not expressed.

Circulating intercellular adhesion molecule-1 and its cellular expression in head and neck non-Hodgkin's lymphomas, including lethal midline granuloma

Extranodal non-Hodgkin's lymphoma in the head and neck, especially T-cell lymphoma of the lethal midline granuloma (LMG) type, has unique clinical and histologic features differentiating it from other lymphomas. The authors measured soluble intercellular adhesion molecule-1 (ICAM-1) in sera from 12 patients with T-cell lymphoma of the LMG type and from 52 patients with other head and neck non-Hodgkin's lymphomas, by double-determinant immunoassay. The expression of ICAM-1 in lymphoma tissue was examined in 26 patients by the avidin-biotin immunoperoxidase method. The serum ICAM-1 levels were significantly higher in T-cell lymphoma of the LMG type than in other head and neck lymphomas or in healthy adult controls. Elevated levels of serum ICAM-1 were associated with increased levels of serum lactate dehydrogenase, poor prognosis, and impaired T-cell-dependent immune functions, both in T-cell lymphoma of the LMG type and in other head and neck lymphomas. When we monitored serum ICAM-1 levels in individual patients, the level decreased in the complete remission interval compared to before treatment and went up again when the lymphoma relapsed. Although the staining intensities of ICAM-1 in lymphoma cells were not related to serum ICAM-1 levels, a markedly intense expression of ICAM-1 was found on the angiocentric or angiodestructive lymphoreticular infiltrate region in the tissues from T-cell lymphoma of the LMG type. A higher serum ICAM-1 level and its tissue expression in T-cell lymphoma of the LMG type may be one of the clues to understanding this particular lymphoma. The serum ICAM-1 level could be an efficient parameter for monitoring the clinical course of head and neck non-Hodgkin's lymphomas.

Immune regulation in Epstein-Barr virus-associated diseases

Epstein-Barr virus (EBV) is a member of the human herpesvirus family and, like many other herpesviruses, maintains a lifelong latent association with B lymphocytes and a permissive association with stratified epithelium in the oropharynx. Clinical manifestations of primary EBV infection range from acute infectious mononucleosis to an asymptomatic persistent infection. EBV is also associated with a number of malignancies in humans. This review discusses features of the biology of the virus, both in cell culture systems and in the natural host, before turning to the role of the immune system in controlling EBV infection in healthy individuals and in individuals with EBV-associated diseases. Cytotoxic T cells that recognize virally determined epitopes on infected cells make up the major effector arm and control the persistent infection. In contrast, the options for immune control of EBV-associated malignancies are more restricted. Not only is antigen expression restricted to a single nuclear antigen, EBNA1, but also these tumor cells are unable to process EBV latent antigens, presumably because of a transcriptional defect in antigen-processing genes (such as TAP1 and TAP2). The likelihood of producing a vaccine capable of controlling the acute viral infection and EBV-associated malignancies is also discussed.

Intercellular adhesion molecule-1 expression by macrophages in human gastrointestinal carcinoma: possible roles as host immune/inflammatory reaction

Tumor-associated macrophages (TAM) are one of the factors which modulate the carcinoma progression. The present study described immunohistochemical expression of intercellular adhesion molecule-1 (ICAM-1) in stromal cells in human gastrointestinal carcinoma identifying the cell types by immunoelectron microscopy. In colon and gastric carcinomas, ICAM-1-positive cells were mostly stromal cells, and major cell types were identified as macrophages and fibroblasts by immunoelectron microscopy. Macrophages were characterized by their ovoid shape, cytoplasmic projections, abundant vacuoles, phagocytosis, and paucity of rough endoplasmic reticulum. Fibroblasts contained stacks of rough endoplasmic reticulum. Macrophages were major cells among ICAM-1-positive cells along the invasive margin, while fibroblasts were predominant in the stroma within carcinoma in colon and intestinal-type gastric carcinomas. Lymphocytes positive for lymphocyte function associated antigen (LFA-1), a counter-receptor of ICAM-1, were densely distributed along the invasive margin, and sparsely in the stroma within carcinoma. In diffuse-type gastric carcinoma, most macrophages were dendritic-shaped and negative for ICAM-1. Our study suggests that the invasive margin is an area similar to active inflammation, where the antigen presenting cells (macrophages) and lymphocytes may interact via the ICAM-1/LFA-1 adhesion.

Novel tumor-associated accessory molecules involved in the gamma/delta cytotoxic T-lymphocyte-Burkitt's lymphoma interaction

BACKGROUND

Tumor specific cytotoxic T lymphocytes (CTL) recognize antigen via the T-cell receptor (TCR). In addition, recognition requires accessory molecules involved in adhesion and signal transduction. The authors previously have characterized an autologous, Burkitt's lymphoma specific CTL line that uses the gamma-delta TCR to recognize antigen in a nonclassical context. The current study was undertaken to identify novel accessory molecules involved in this unusual TCR-tumor cell interaction.

METHODS

A panel of monoclonal antibodies was generated against a Burkitt's lymphoma cell line and was screened for inhibition of autologous, tumor specific, cytolysis by a gamma-delta CTL line. Proteins identified by these monoclonal antibodies were further characterized by fluorescent-activated cell sorter analysis, Western blot and immunoprecipitation.

RESULTS

Three known (CD5, CD43, and CD11a/CD18) and three novel (BAM-1, BAM-2, and BAM-3) cell surface molecules involved in the gamma-delta CTL-Burkitt's lymphoma interaction were identified and characterized.

CONCLUSIONS

This study identifies and provides a preliminary characterization of three novel Burkitt's lymphoma-associated molecules involved in the gamma-delta CTL-tumor cell interaction and demonstrates that CD5, CD43, and CD11a/CD18 are involved in this interaction. It is likely that other unidentified accessory molecules are also involved in this and other effector cell-tumor interactions. Identification of such molecules may be useful in the design of new immunotherapeutic approaches.

Expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in undifferentiated nasopharyngeal carcinoma (lymphoepithelioma) and in malignant epithelial tumors

Immunoreactivity for intercellular adhesion molecule-1 (ICAM-1) and for vascular cell adhesion molecule-1 (VCAM-1), two adhesion molecules of the immunoglobulin (Ig) superfamily, was tested and measured on tissue sections from 16 undifferentiated nasopharyngeal carcinomas (U-NPC), 12 keratinizing squamous cell carcinomas (SCCs) of the head and neck region, and 54 malignant epithelial tumors of various origin. Neoplastic cells of all cases of U-NPC were diffusely and intensely stained for ICAM-1 and VCAM-1. Moreover, ICAM-1 messenger RNA (mRNA) and VCAM-1 mRNA were detected by Northern blot analysis of RNA extracts from two tumors. In the other epithelial tumors focal or diffuse staining for ICAM-1 was observed in 40 cases (66%), whereas reactivity for VCAM-1 was detected in a single case of metastatic undifferentiated carcinoma of unknown origin. The biopsy specimens of U-NPC showed variable infiltration by leukocytes, which were positive for the integrins lymphocyte function antigen-1 (LFA-1) and alpha-4/beta-1, the corresponding ligands for ICAM-1 and VCAM-1. The possibility that ICAM-1 and VCAM-1 on neoplastic cells may favor the intratumoral recruitment of leukocytes in a way similar to that occurring in crypt epithelium of the palatine tonsil is discussed.

Characteristic clinicopathologic features of Epstein-Barr virus-associated peripheral T-cell lymphoma

BACKGROUND

The authors previously reported the existence of a unique subtype of peripheral T-cell lymphoma (PTCL) characterized by a clonotypical proliferation of Epstein-Barr virus (EBV) in the tumor cells (Blood 1991; 77:799). Detailed clinicopathologic features of this newly recognized entity remain to be clarified.

METHODS

A retrospective study was done in 23 patients receiving consecutive diagnoses at National Taiwan University Hospital by methods previously described.

RESULTS

There were 13 male and 10 female patients, with a median age of 40 years. Seventeen patients had Stage III/IV disease, and 15 patients had fever as a presenting B symptom. Initial extranodal involvement occurred in skin (10 patients), lung (4 patients), bone marrow (4 patients), brain (3 patients), and nasal cavity (1 patient) and was evidenced by hepatosplenomegaly (6 patients). Sixteen patients had specific histopathologic features including characteristics similar to angioimmunoblastic lymphadenopathy with dysproteinemia (3 patients), angioinvasive-type features (6 patients), Hodgkin disease-like features (2 patients), hepatosinusoidal-type features (2 patients), Lennert lymphoma (2 patients), and malignant histiocytosis-like features (1 patient). Six (37.5%) of the 16 patients who received a standard regimen with cyclophosphamide, doxorubicin, vincristine, and prednisone or an equivalent regimen as induction chemotherapy achieved complete remission. The median survival time was only 8 months. Six (42.8%) of the 14 patients who have died at this report ended up with a terminal hemophagocytosis syndrome. All five relapsed tumors were found to have a strong expression of P-glycoprotein (P-gp).

CONCLUSIONS

The authors suggest that EBV-associated PTCL should be regarded as a separate entity of non-Hodgkin lymphoma showing characteristic histopathologic features, frequent expression of P-gp in relapsed tumor, a terminal hemophagocytosis syndrome, and a generally ominous outcome.