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The Epstein-Barr Virus (EBV) is involved in the etiology of multiple hematologic and epithelial human cancers. EBV+ tumors employ multiple immune escape mechanisms, including the recruitment of immunosuppressive regulatory T cells (Treg). Here, we show some EBV+ tumor cells express high levels of the chemokines CCL17 and CCL22 both in vitro and in vivo and that this expression mirrors the expression levels of expression of the EBV LMP1 gene in vitro. Patient samples from lymphoblastic (Hodgkin lymphoma) and epithelial (nasopharyngeal carcinoma; NPC) EBV+ tumors revealed CCL17 and CCL22 expression of both tumor cell-intrinsic and -extrinsic origin, depending on tumor type. NPCs grown as mouse xenografts likewise showed both mechanisms of chemokine production. Single cell RNA-sequencing revealed in vivo tumor cell-intrinsic CCL17 and CCL22 expression combined with expression from infiltrating classical resident and migratory dendritic cells in a CT26 colon cancer mouse tumor engineered to express LMP1. These data suggest that EBV-driven tumors employ dual mechanisms for CCL17 and CCL22 production. Importantly, both in vitro and in vivo Treg migration was effectively blocked by a novel, small molecule antagonist of CCR4, CCR4-351. Antagonism of the CCR4 receptor may thus be an effective means of activating the immune response against a wide spectrum of EBV+ tumors. Author summary: The Epstein-Barr Virus (EBV) is associated with many cancers worldwide, including both lymphomas and solid tumors. EBV+ tumors have been reported to have increased numbers of infiltrating regulatory T cells (Treg), a cell type that counteracts the body's natural antitumor response. Here we show that EBV+ tumors actually have amongst the highest levels of Treg of all human tumors, as well as having very high levels of the chemokines CCL17 and CCL22, signaling molecules that promote the migration of Treg. We found that CCL17 and CCL22 production in different EBV+ tumor cell lines mirrored the levels of production of the EBV protein LMP1, and that the LMP1 gene on its own was sufficient to trigger chemokine expression and Treg migration into a mouse tumor model. Depending on the particular EBV+ tumor type, this CCL17 and CCL22 expression could be coming from the tumor cells themselves, infiltrating host immune cells, or a combination of the two. A recently developed drug that blocks the activity of CCL17 and CCL22 blocked Treg migration into EBV+ and LMP1+ tumors, suggesting that this may be part of an effective treatment for EBV+ tumors in the clinic, helping to reduce the over 140,000 annual deaths from this group of cancers. [ABSTRACT FROM AUTHOR]

Around 30–50% of classical Hodgkin lymphoma (cHL) cases in immunocompetent individuals from industrialized countries are associated with the B-lymphotropic Epstein-Barr virus (EBV). Although natural killer (NK) cells exhibit anti-viral and anti-tumoral functions, virtually nothing is known about quantitative and qualitative differences in NK cells in patients with EBV+ cHL vs. EBV- cHL. Here, we prospectively investigated 36 cHL patients without known immune suppression or overt immunodeficiency at diagnosis. All 10 EBV+ cHL patients and 25 out 26 EBV- cHL were seropositive for EBV antibodies, and EBV+ cHL patients presented with higher plasma EBV DNA levels compared to EBV- cHL patients. We show that the CD56dim CD16+ NK cell subset was decreased in frequency in EBV+ cHL patients compared to EBV- cHL patients. This quantitative deficiency translates into an impaired CD56dim NK cell mediated degranulation toward rituximab-coated HLA class 1 negative lymphoblastoid cells in EBV+ compared to EBV- cHL patients. We finally observed a trend to a decrease in the rituximab-associated degranulation and ADCC of in vitro expanded NK cells of EBV+ cHL compared to healthy controls. Our findings may impact on the design of adjunctive treatment targeting antibody-dependent cellular cytotoxicity in EBV+ cHL. [ABSTRACT FROM AUTHOR]

Abstract: Nasopharyngeal carcinoma (NPC) is a highly invasive epithelial malignancy that is prevalent in southern China and Southeast Asia. It is consistently associated with latent Epstein–Barr virus (EBV) infection. In NPC, miR‐BARTs, the EBV‐encoded miRNAs derived from BamH1‐A rightward transcripts, are abundantly expressed and contribute to cancer development by targeting various cellular and viral genes. In this study, we establish a comprehensive transcriptional profile of EBV‐encoded miRNAs in a panel of NPC patient‐derived xenografts and an EBV‐positive NPC cell line by small RNA sequencing. Among the 40 miR‐BARTs, predominant expression of 22 miRNAs was consistently detected in these tumors. Among the abundantly expressed EBV‐miRNAs, BART5‐5p, BART7‐3p, BART9‐3p, and BART14‐3p could negatively regulate the expression of a key DNA double‐strand break (DSB) repair gene, ataxia telangiectasia mutated (ATM), by binding to multiple sites on its 3'‐UTR. Notably, the expression of these four miR‐BARTs represented more than 10% of all EBV‐encoded miRNAs in tumor cells, while downregulation of ATM expression was commonly detected in all of our tested sequenced samples. In addition, downregulation of ATM was also observed in primary NPC tissues in both qRT‐PCR (16 NP and 45 NPC cases) and immunohistochemical staining (35 NP and 46 NPC cases) analysis. Modulation of ATM expression by BART5‐5p, BART7‐3p, BART9‐3p, and BART14‐3p was demonstrated in the transient transfection assays. These findings suggest that EBV uses miRNA machinery as a key mechanism to control the ATM signaling pathway in NPC cells. By suppressing these endogenous miR‐BARTs in EBV‐positive NPC cells, we further demonstrated the novel function of miR‐BARTs in inhibiting Zta‐induced lytic reactivation. These findings imply that the four viral miRNAs work co‐operatively to modulate ATM activity in response to DNA damage and to maintain viral latency, contributing to the tumorigenesis of NPC. © 2017 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

Nasopharyngeal carcinoma (NPC) most frequently occurs in southern China and southeast Asia. Epidemiology studies link NPC to genetic predisposition, Epstein--Barr virus (EBV) infection, and environmental factors. Genetic studies indicate that mutations in chromatin-modifying enzymes are the most frequent genetic alterations in NPC. Here, we used H3K27ac chromatin immune precipitation followed by deep sequencing (ChIP-seq) to define the NPC epigenome in primary NPC biopsies, NPC xenografts, and an NPC cell line, and compared them to immortalized normal nasopharyngeal or oral epithelial cells. We identified NPC-specific enhancers and found these enhancers were enriched with nuclear factor κB (NF-κB), IFN-responsive factor 1 (IRF1) and IRF2, and ETS family members ETS1 motifs. Normal cell-specific enhancers were enriched with basic leucine zipper family members and TP53 motifs. NPC super-enhancers with extraordinarily broad and high H3K27ac signals were also identified, and they were linked to genes important for oncogenesis including ETV6. ETV6 was also highly expressed in NPC biopsies by immunohistochemistry. High ETV6 expression correlated with a poor prognosis. Furthermore, we defined the EBV episome epigenetic landscapes in primary NPC tissue. [ABSTRACT FROM AUTHOR]

As a distinct type of head and neck cancer, non-keratinizing nasopharyngeal carcinoma ( NPC) is closely associated with EBV infection and massive lymphoid infiltration. The unique histological features suggest that local inflammation plays an important role in NPC tumourigenesis. We comprehensively characterized NF-κB signalling, a key inflammatory pathway which might contribute to the tumourigenesis of this EBV-associated cancer. By EMSA, western blotting, and immunohistochemical staining, constitutive activation of distinct NF-κB complexes, either p50/p50/Bcl3 or p50/ RelB, was found in almost all EBV-positive NPC tumours. siRNA or chemical inhibition of NF-κB signalling significantly inhibited the growth of EBV-positive NPC cells C666-1. Gene expression profiling identified a number of NF-κB target genes involved in cell proliferation, apoptosis, immune response, and transcription. We further confirmed that p50 signals modulate the expression of multiple oncogenes ( MYB, BCL2), chemokines, and chemokine receptors ( CXCL9, CXCL10, CX3CL1, and CCL20). The findings support a crucial role of these constitutively activated NF-κB signals in NPC tumourigenesis and local inflammation. In addition to expression of the viral oncoprotein LMP1, genetic alteration of several NF-κB regulators (eg TRAF3, TRAF2, NFKBIA, A20) also contributes to the aberrant NF-κB activation in EBV-associated NPC. Except for LMP1-expressing C15 cells, all NPC tumour lines harbour at least one of these genetic alterations. Importantly, missense mutations of TRAF3, TRAF2, and A20 were also detected in 3/33 (9.1%) primary tumours. Taken together with the reported LTBR amplification in 7.3% of primary NPCs, genetic alterations in NF-κB pathways occurred in at least 16% of cases of this cancer. The findings indicate that distinct NF-κB signals are constitutively activated in EBV-positive NPC cells by either multiple genetic changes or EBV latent genes. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Nasopharyngeal carcinoma ( NPC) is a distinct type of head and neck cancer which is prevalent in southern China, south-east Asia and northern Africa. The development and stepwise progression of NPC involves accumulation of multiple gross genetic changes during the clonal expansion of Epstein-Barr virus ( EBV)-infected nasopharyngeal epithelial cell population. Here, using paired-end whole-transcriptome sequencing, we discovered a number of chimeric fusion transcripts in a panel of EBV-positive tumour lines. Among these transcripts, a novel fusion of ubiquitin protein ligase E3 component n-recognin 5 ( UBR5) on 8q22.3 and zinc finger protein 423 ( ZNF423) on 16q12.1, identified from the NPC cell line C666-1, was recurrently detected in 12/144 (8.3%) of primary tumours. The fusion gene contains exon 1 of UBR5 and exons 7-9 of ZNF423 and produces a 94 amino acid chimeric protein including the original C-terminal EBF binding domain ( ZF29-30) of ZNF423. Notably, the growth of NPC cells with UBR5-ZNF423 rearrangement is dependent on expression of this fusion protein. Knock-down of UBR5-ZNF423 by fusion-specific siRNA significantly inhibited the cell proliferation and colony-forming ability of C666-1 cells. The transforming ability of UBR5-ZNF423 fusion was also confirmed in NIH3T3 fibroblasts. Constitutive expression of UBR5-ZNF423 in NIH3T3 fibroblasts significantly enhanced its anchorage-independent growth in soft agar and induced tumour formation in a nude mouse model. These findings suggest that expression of UBR5-ZNF423 protein might contribute to the transformation of a subset of NPCs, possibly by altering the activity of EBFs (early B cell factors). Identification of the oncogenic UBR5-ZNF423 provides new potential opportunities for therapeutic intervention in NPC. © 2013 The Authors. Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

Background: Because latent Epstein Barr (EBV)-infection is a specific characteristic of malignant nasopharyngeal carcinoma (NPC), various molecules of viral origin are obvious candidate biomarkers in this disease. In a previous study, we could show in a few clinical samples that it was possible to detect a category of EBV microRNAs called miR-BARTs in the plasma of at least a fraction of NPC patients. The first aim of the present study was to investigate the status of circulating miR-BART17-5p (one of the miR-BARTs hereafter called miR-BART17) and EBV DNA in a larger series of NPC plasma samples. The second aim was to determine whether or not circulating miR-BART17 was carried by plasma exosomes. Patients and methods: Plasma samples were collected from 26 NPC patients and 10 control donors, including 9 patients with non-NPC Head and Neck squamous cell carcinoma and one healthy EBV carrier. Concentrations of miR-BART17 and two cellular microRNAs (hsa-miR-16 and -146a) were assessed by real-time quantitative PCR with spike-in normalization and absolute quantification. In addition, for 2 patients, exosome distributions of miR-BART17 and miR-16 were investigated following plasma lipoprotein fractionation by isopycnic density gradient ultrcentrifugation. Results: The miR-BART17 was significantly more abundant in plasma samples from NPC patients compared to non-NPC donors. Above a threshold of 506 copies/mL, detection of miR-BART17 was highly specific for NPC patients (ROC curve analysis: AUC=0.87 with true positive rate = 0.77, false positive rate = 0.10). In this relatively small series, the concentration of plasma miR-BART17 and the plasma EBV DNA load were not correlated. When plasma samples were fractionated, miR-BART17 co-purified with a protein-rich fraction but not with exosomes. Conclusions: Detection of high concentrations of plasma miR-BART17 is consistent in NPC patients. This parameter is, at least in part, independent of the viral DNA load. Circulating miR-BART17 does not co-purify with exosomes. [ABSTRACT FROM AUTHOR]

Background: Nasopharyngeal carcinomas (NPC) are consistently associated with the Epstein-Barr virus (EBV). Though NPCs are more radiosensitive and chemosensitive than other tumors of the upper aero-digestive tract, many therapeutic challenges remain. In a previous report, we have presented data supporting a possible therapeutic strategy based on artificial TLR3 stimulation combined to the inhibition of the IAP protein family (Inhibitor of Apoptosis Proteins). The present study was designed to progress towards practical applications of this strategy pursuing 2 main objectives: 1) to formally demonstrate expression of the TLR3 protein by malignant NPC cells; 2) to investigate the effect of poly(A:U) as a novel TLR3-agonist more specific than poly(I:C) which was used in our previous study. Methods: TLR3 expression was investigated in a series of NPC cell lines and clinical specimens by Western blot analysis and immunohistochemistry, respectively. The effects on NPC cells growth of the TLR3 ligand poly(A:U) used either alone or in combination with RMT5265, an IAP inhibitor based on Smac-mimicry, were assessed using MTT assays and clonogenic assays. Results: TLR3 was detected at a high level in all NPC cell lines and clinical specimens. Low concentrations of poly(A: U) were applied to several types of NPC cells including cells from the C17 xenograft which for the first time have been adapted to permanent propagation in vitro. As a single agent, poly(A:U) had no significant effects on cell growth and cell survival. In contrast, dramatic effects were obtained when it was combined with the IAP inhibitor RMT5265. These effects were obtained using concentrations as low as 0.5 μg/ml (poly(A:U)) and 50 nM (RMT5265). Conclusion: These data confirm that TLR3 expression is a factor of vulnerability for NPC cells. They suggest that in some specific pathological and pharmacological contexts, it might be worth to use Smac-mimetics at very low doses, allowing a better management of secondary effects. In light of our observations, combined use of both types of compounds should be considered for treatment of nasopharyngeal carcinomas. [ABSTRACT FROM AUTHOR]

Background: Nasopharyngeal carcinoma (NPC) is a human epithelial malignancy consistently associated with the Epstein-Barr virus. The viral genome is contained in the nuclei of all malignant cells with abundant transcription of a family of viral microRNAs called BART miRNAs. MicroRNAs are well known intra-cellular regulatory elements of gene expression. In addition, they are often exported in the extra-cellular space and sometimes transferred in recipient cells distinct from the producer cells. Extra-cellular transport of the microRNAs is facilitated by various processes including association with protective proteins and packaging in secreted nanovesicles called exosomes. Presence of microRNAS produced by malignant cells has been reported in the blood and saliva of tumor-bearing patients, especially patients diagnosed with glioblastoma or ovarian carcinoma. In this context, it was decided to investigate extra-cellular release of BART miRNAs by NPC cells and their possible detection in the blood of NPC patients. To address this question, we investigated by quantitative RT-PCR the status of 5 microRNAs from the BART family in exosomes released by NPC cells in vitro as well as in plasma samples from NPC xenografted nude mice and NPC patients. Results: We report that the BART miRNAs are released in the extra-cellular space by NPC cells being associated, at least to a large extent, with secreted exosomes. They are detected with a good selectivity in plasma samples from NPC xenografted nude mice as well as NPC patients. Conclusions: Viral BART miRNAs are secreted by NPC cells in vitro and in vivo. They have enough stability to diffuse from the tumor site to the peripheral blood. This study provides a basis to explore their potential as a source of novel tumor biomarkers and their possible role in communications between malignant and nonmalignant cells. [ABSTRACT FROM AUTHOR]

Undifferentiated nasopharyngeal carcinoma (NPC) is tightly associated with the Epstein-Barr virus (EBV) and very heavily infiltrated with T lymphocytes. We demonstrated recently that NPC epithelial cells produce immuno-regulatory molecules, including the Blast-2/CD23 antigen, which is induced in B lymphocytes upon infection by EBV. We demonstrate here that CD23 expression is a non-constant but highly specific feature of epithelial cells from NPC. The C15 and C17 NPC tumor cells express mainly the b form of CD23, which is known to be non-lineage-specific and IL-4-inducible. C17 cells were found also to weakly express the a form of CD23, which has been described as B cell-specific. In addition, several factors potentially released by tumor infiltrating lymphocytes (TILs) are able to regulate CD23 expression in NPC cells. In particular, we found that IL-4 was a potent inducer of CD23 expression in C15 cells, as shown at both the protein and the mRNA levels. These results, together with the already reported expression of class II MHC antigens and the release of IL-1 by NPC cells, suggest that the interactions between TILs and malignant cells are a key factor in NPC pathogenesis and development. [ABSTRACT FROM PUBLISHER]

A letter to the editor is presented in response to the article "Profiling of Epstein-BarrVirus-Encoded MicroRNAs inNasopharyngeal CarcinomaReveals Potential Biomarkersand Oncomirs," by Wong AM, Kong KL and colleagues is presented and also includes the reply from the author.

BALF0/1 is a putative Epstein-Barr virus (EBV) protein that has been described as a modulator of apoptosis. So far, the lack of specific immunological reagents impaired the detection of native BALF0/1 in EBV-infected cells. This study describes the expression and purification of a truncated form of BALF0/1 (tBALF0) using a heterologous bacterial expression system. tBALF0 was further used as an antigen in an indirect Enzyme-linked Immunosorbent Assay (ELISA) that unraveled the presence of low titer IgGs to BALF0/1 during primary (10.0%) and past (13.3%) EBV infection. Conversely high-titer IgGs to BALF0/1 were detected in 33.3% of nasopharyngeal carcinoma (NPC) patients suggesting that BALF0/1 and/or humoral response against it may contribute to NPC pathogenesis. • A truncated form of BALF0/1 (tBALF0) could be expressed and purified in E. coli. • IgGs against BALF0/1 were detected in various physiopathological situations. • 33.3% of NPC patients secreted high titer IgG against BALF0/1. [ABSTRACT FROM AUTHOR]

Nasopharyngeal carcinomas (NPC) are etiologically related to the Epstein-Barr virus (EBV), and malignant NPC cells have consistent although heterogeneous expression of the EBV latent membrane protein 1 (LMP1). LMP1 trafficking and signaling require its incorporation into membrane rafts. Conversely, raft environment is likely to modulate LMP1 activity. In order to investigate NPC-specific raft partners of LMP1, rafts derived from the C15 NPC xenograft were submitted to preparative immunoprecipitation of LMP1 combined with mass spectrometry analysis of coimmunoprecipitated proteins. Through this procedure, galectin 9, a beta-galactoside binding lectin and Hodgkin tumor antigen, was identified as a novel LMP1 partner. LMP1 interaction with galectin 9 was confirmed by coimmunoprecipitation and Western blotting in whole-cell extracts of NPC and EBV-transformed B cells (lymphoblastoid cell lines [LCLs]). Using mutant proteins expressed in HeLa cells, LMP1 was shown to bind galectin 9 in a TRAF3-independent manner. Galectin 9 is abundant in NPC biopsies as well as in LCLs, whereas it is absent in Burkitt lymphoma cells. In subsequent experiments, NPC cells were treated with Simvastatin, a drug reported to dissociate LMP1 from membrane rafts in EBV-transformed B cells. We found no significant effects of Simvastatin on the distribution of LMP1 and galectin 9 in NPC cell rafts. However, Simvastatin was highly cytotoxic for NPC cells, regardless of the presence or absence of LMP 1. This suggests that Simvastatin is a potentially useful agent for the treatment of NPCs although it has distinct mechanisms of action in NPC and LCL cells. [ABSTRACT FROM AUTHOR]

Successful attainment of tumor-specific gene expression was achieved in nasopharyngeal carcinoma (NPC) by exploiting the exclusive presence of the Epstein–Barr virus (EBV) genome in the cancer cells. In the current study, we have utilized an EBV-dependent transcriptional targeting strategy to construct a novel conditionally replicating adenovirus, adv.oriP.E1A. After treatment with adv.oriP.E1A, we observed extensive cell death in the EBV-positive NPC cell line C666-1. In contrast, no cytotoxicity was observed in a panel of other human EBV-negative cell lines, including fibroblasts from the nasopharynx. In vitro adenoviral replication was confirmed by the time-dependent increase in the expression of adenoviral capsid fiber protein and adenoviral DNA after C666-1 cells were infected with adv.oriP.E1A. Tumor formation was inhibited for more than 100 days after ex vivo infection of C666-1 cells with adv.oriP.E1A. Combination of local tumor radiation and adv.oriP.E1A caused complete disappearance of established tumors for at least 2 weeks in two distinct EBV-positive NPC xenograft models. Safety of this treatment was determined through the systemic delivery of adv.oriP.E1A in vivo, whereby minimal temporary perturbation of liver function was observed. We have successfully established a conditionally replicating adenovirus for EBV-positive NPC, which is both safe and efficacious, indicating a strategy that may be therapeutically applicable. [Copyright &y& Elsevier]

We have successfully achieved selective gene expression in human nasopharyngeal carcinoma (NPC) by exploiting the presence of the Epstein–Barr virus (EBV), utilizing a transcriptional targeting strategy (J. H. Li et al., 2002, Cancer Res. 62: 171). Building on this platform, we have generated a novel ΔE1 adenoviral vector mediating the expression of a mutant noncleavable form of the FasL gene (HUGO-approved symbol TNFSF6) (ad5oriP.ncFasL). We observe that this therapy induces significant cytotoxicity in the EBV-positive NPC cell line C666-1, mediated by the induction of caspase-dependent apoptosis. The addition of ionizing radiation therapy (RT) causes additional cytotoxicity. Ex vivo infection of C666-1 cells with adv.oriP.ncFasL completely prevents tumor formation in SCID mice followed for up to 100 days. The combination of intratumoral adv.oriP.ncFasL with RT causes regression of established nasopharyngeal xenograft tumors for 2 weeks'' duration. Systemic delivery of this targeted strategy achieves 50-fold higher gene expression in nasopharyngeal tumors than in normal organs. Intravenously injected adv.oriP.ncFasL results in mild perturbation of liver function that returns to normal 2 weeks after initial therapy. These results demonstrate the efficacy of our EBV-specific targeting strategy, which allows the potentially safe and effective utilization of a highly potent membrane-based apoptotic gene. [Copyright &y& Elsevier]

Nasopharyngeal carcinomas (NPCs) are consistently associated with the Epstein–Barr virus (EBV). As Bcl-2 and Bcl-X are co-expressed in EBV-transformed B-lymphocytes, we attempted to determine their status in malignant NPC cells. A retrospective series of 100 NPC specimens from untreated Tunisian patients was investigated by immuno-histochemistry. Twenty seven of the patients were below 30 years old and therefore classified in the “juvenile” form of north African NPCs. Bcl-2 and Bcl-X expression was assessed semi-quantitatively using a score based on the percentage of positive cells and staining intensity. Intense Bcl-X expression was detected in malignant cells of 100% biopsy samples with similar scores for patients below 30 years or those aged 30 or over. Bcl-2 was detected in 89% biopsies but its expression differed considerably between the samples. The average Bcl-2 score was much lower for patients under 30 years (4.4±1.5 compared to 6.5±2 for older patients; P<10−6). Multivariate analysis demonstrated that no other clinical parameter, except the primary tumor size, was correlated to the Bcl-2 score. Bcl-X and Bcl-2 are co-expressed in 89% of NPCs whereas their expression is mutually exclusive in other head and neck carcinomas (particularly squamous cell carcinomas, SCC). The constantly high expression of Bcl-X is consistent with it being induced by the EBV protein Epstein–Barr nuclear antigen 1 (EBNA1), as recently reported in a murine model. The contrasted levels of Bcl-2 expression in the two age groups strengthen the hypothesis that these clinical forms result from distinct oncogenic mechanisms. [Copyright &y& Elsevier]

Epstein-Barr virus (EBV)-associated nasopharyngeal carcinomas (NPC) are much more sensitive to chemotherapy than other head and neck carcinomas. Spectacular regressions are frequently observed after induction chemotherapy. However, these favorable responses are difficult to predict and often of short duration. So far there have been only few experiments to investigate the mechanisms which underline the cytotoxic effects of anti-neoplastic drugs against NPC cells. In addition, these studies were performed almost entirely on EBV-negative cell lines therefore not truly representative of NPC cells. For the first time, we have used two EBV-positive NPC tumor lines derived from a North African (C15) and a Chinese (C666-1) patient as in vitro targets for a panel of anti-neoplastic agents. Doxorubicin, taxol and in a lesser extent cis-platinum efficiently inhibited NPC cell proliferation at clinically relevant concentrations, but all three agents failed to induce apoptosis. However, massive apoptosis of C15 cells was achieved when doxorubicin (1 μM) was combined with a farnesyl-transferase inhibitor, BIM 2001 (5 μM). Moreover, this apoptotic process was associated with a caspase-dependent early cleavage of the TNF-receptor associated factor 1 (TRAF-1) molecule, a signaling adaptor which is specifically expressed in latently EBV-infected cells. TRAF-1 cleavage might become a useful indicator of chemo-induced apoptosis in EBV-associated NPCs. [Copyright &y& Elsevier]