P53 overexpression and Epstein-Barr virus infection in undifferentiated and squamous cell nasopharyngeal carcinomas

LMP1 Induces p53 Protein Expression via the H19/miR-675-5p Axis

Epstein-Barr virus (EBV), a ubiquitous oncogenic herpesvirus, infects more than 90% of the adult population worldwide. The long noncoding RNA H19 is downregulated in EBV-positive gastric cancer (EBVaGC) and nasopharyngeal cancer (NPC). In this study, we found that loss of H19 is caused by hypermethylation status of the H19 promoter in EBV-positive GC and NPC cell lines. Furthermore, latent membrane protein 1 (LMP1), encoded by EBV, induced H19 promoter hypermethylation and deregulated the expression of H19 by upregulating DNMT1 expression. Transwell assays showed that H19 promoted cell migration. Furthermore, H19 promoted cell proliferation and inhibited apoptosis in CCK-8 and flow cytometry assays, respectively. p53, a well-known tumor suppressor, was upregulated in EBVaGC and NPC cell lines. miR-675-5p derived from H19 inhibited p53 protein expression by targeting the 3' untranslated region of the gene. Overall, we found that LMP1 induced p53 protein expression via the H19/miR-675-5p axis in EBVaGC and NPC. LMP1 induced H19 promoter hypermethylation, which repressed the expression of H19 and miR-675-5p and caused p53 protein overexpression in EBVaGC and NPC cells. IMPORTANCE Epstein-Barr virus (EBV) is the first virus to be known to have direct association with human cancer and to be considered as an important DNA tumor virus. The EBV life cycle consists of both latent and lytic modes of infection in B lymphocytes and epithelial cells. The persistence of EBV genomes in malignant cells promoted cell growth. p53, acting as a critical gatekeeper tumor suppressor, is involved in multiple virus-mediated tumorigeneses. Overexpression of p53 inhibits the ability of BZLF1 (EBV-encoded immediate early gene) to disrupt viral latency. In our study, we found LMP1 induces H19 promoter hypermethylation, which represses the expression of H19 and miR-675-5p and results in p53 protein overexpression in EBVaGC and NPC cells. These observations suggest a new mechanism of aberrant expression of p53 by LMP1, which facilitates EBV latency.

Emerging therapeutic targets for nasopharyngeal carcinoma: opportunities and challenges

Introduction: Nasopharyngeal carcinoma (NPC) is a major public health problem in several countries, especially those in Southeast Asia and North Africa. In its typical poorly differentiated form, the Epstein-Barr virus (EBV) genome is present in the nuclei of all malignant cells with restricted expression of a few viral genes. The malignant phenotype of NPC cells results from the influence of these viral products in combination with cellular genetic, epigenetic and functional alterations. With regard to host/tumor interactions, NPC is a remarkable example of immune escape in the context of a hot tumor.Areas covered: This article has an emphasis on emerging therapeutic targets that are considered upstream or at an early stage of clinical application. It examines targets related to cellular oncogenic alterations, latent EBV infection and tumor interactions with the immune system.Expert opinion: There is a remarkable emergence of new agents that target EBV products. The clinical application of these agents would benefit from a systematic and comprehensive molecular classification of NPCs and from easy access to pre-clinical models in public repositories. There is a strong rationale for more investigations on the potential of immune modulators, especially those related to NK cells.

Nasopharyngeal Carcinoma and Epstein-Barr Virus Infection in Japanese Patients

Of 38 Japanese patients with nasopharyngeal malignancies, Epstein-Barr virus (EBV) infection and neck metastasis were investigated. Thirty-three patients had nasopharyngeal carcinoma: moderately differentiated squamous cell carcinoma, poorly differentiated squamous cell carcinoma, and undifferentiated carcinoma. Formalin-fixed and paraffin-embedded surgical specimens were studied by in situ hybridization technique detecting EBER 1, which is EBV-encoded, small molecular nonpolyadenylated RNA. “EBER 1 positive” rates of moderately differentiated squamous cell carcinoma, poorly differentiated squamous cell carcinoma, and undifferentiated carcinoma were 29%, 80%, and 88%, respectively. On the other hand, neck metastasis in each group was found 71%, 70%, and 75%, respectively. The possible role of EBV in nasopharyngeal carcinoma was discussed.

p53 Protein and Proliferating Cell Nuclear Antigen (PCNA) Expression in Small Round Cell Tumors of Bone and Adjacent Soft Tissue

Sixty small cell tumors of bone and adjacent soft tissue were studied in an attempt to define the incidence of immunohistochemically detectable p53 protein and cor relate these findings with the results of proliferating cell nuclear antigen (PCNA) immunohistochemical staining and mitotic counts. All of the lesions had been for malin-fixed and paraffin-embedded; half were subjected to decalcification prior to processing. The study population included 12 Ewing's sarcomas of bone, 3 atypical Ewing's sarcomas of bone, 3 primitive neuroectodermal tumors of bone, 11 Askin tumors of the thoracopulmonary region, 11 small cell osteosarcomas of bone, 10 mesenchymal chondrosarcomas of bone, and 10 malignant lymphomas involving bone. The patients ranged in age at the time of presentation from 17 to 67 years. Overall, the incidence of p53 positivity was extremely low in these lesions, irre spective of tumor type. Positive nuclear staining with an antibody to p53 was found in none of the 12 Ewing's sarcomas, none of the 3 atypical Ewing's sarcomas, none of the 3 primitive neuroectodermal tumors of bone, 1 of the 11 Askin tumors of the thoracopulmonary region (1.5% of tumor cells positive), 1 of the 11 small cell osteosarcomas (2% of tumor cells positive), 1 of the 10 mesenchymal chondrosar comas of bone (7% of tumor cells positive), and 2 of the 10 malignant lymphomas involving bone (0.5% and 1% of tumor cells positive, respectively). The majority of tumors showed PCNA positivity within the tumor cells, although the incidence of PCNA positivity within the histologic types varied greatly; in general, the higher PCNA counts corresponded to higher mitotic counts within the individual lesions. The present study did not demonstrate any correlation between mutant p53 accu mulation detected by immunohistochemistry and tumor type, and so it is unlikely that p53 positivity will prove to be of great use in the differential diagnosis of these lesions. A correlation between p53 positivity and PCNA staining or mitotic activity was not apparent. Int J Surg Pathol 2(4):259-268, 1995

The Role of Gammaherpesviruses in Cancer Pathogenesis

Worldwide, one fifth of cancers in the population are associated with viral infections. Among them, gammaherpesvirus, specifically HHV4 (EBV) and HHV8 (KSHV), are two oncogenic viral agents associated with a large number of human malignancies. In this review, we summarize the current understanding of the molecular mechanisms related to EBV and KSHV infection and their ability to induce cellular transformation. We describe their strategies for manipulating major cellular systems through the utilization of cell cycle, apoptosis, immune modulation, epigenetic modification, and altered signal transduction pathways, including NF-kB, Notch, Wnt, MAPK, TLR, etc. We also discuss the important EBV latent antigens, namely EBNA1, EBNA2, EBNA3’s and LMP’s, which are important for targeting these major cellular pathways. KSHV infection progresses through the engagement of the activities of the major latent proteins LANA, v-FLIP and v-Cyclin, and the lytic replication and transcription activator (RTA). This review is a current, comprehensive approach that describes an in-depth understanding of gammaherpes viral encoded gene manipulation of the host system through targeting important biological processes in viral-associated cancers.

A Review: Proteomics in Nasopharyngeal Carcinoma

Although radiotherapy is generally effective in the treatment of major nasopharyngeal carcinoma (NPC), this treatment still makes approximately 20% of patients radioresistant. Therefore, the identification of blood or biopsy biomarkers that can predict the treatment response to radioresistance and that can diagnosis early stages of NPC would be highly useful to improve this situation. Proteomics is widely used in NPC for searching biomarkers and comparing differentially expressed proteins. In this review, an overview of proteomics with different samples related to NPC and common proteomics methods was made. In conclusion, identical proteins are sorted as follows: Keratin is ranked the highest followed by such proteins as annexin, heat shock protein, 14-3-3σ, nm-23 protein, cathepsin, heterogeneous nuclear ribonucleoproteins, enolase, triosephosphate isomerase, stathmin, prohibitin, and vimentin. This ranking indicates that these proteins may be NPC-related proteins and have potential value for further studies.

Molecular characterization and clinical implications of spindle cells in nasopharyngeal carcinoma: a novel molecule-morphology model of tumor progression proposed

Up to now, the precise molecular and morphological changes underlying the invasive and metastatic properties of nasopharyngeal carcinoma (NPC) remain largely unresolved. We speculate that neoplastic spindle cells, which are prominently found in the invasive tumor front and the surrounding stroma, might be responsible for the aggressive patterns. Expression profiling of various biomarkers relevant to cancer stem cells (CSCs) and epithelial-mesenchymal transition (EMT) was performed by tissue microarray-based immunohistochemistry in NPC samples. The expression of EBER and LMP1 was detected by in situ hybridization and immunohistochemistry, respectively. We found that overexpression of CSCs-related markers (ALDH1, Nanog and ABCG2) and up-regulation of EMT markers (Fibronectin, MMP-2, Periostin, SPARC, Snail and Slug), together with E- to N-cadherin switching, occurred preferentially in tumors containing a large proportion of spindle-shaped malignant cells. Furthermore, CSCs-like properties were highly present in spindle cells compared with non-spindle cells of tumors, and correlated strongly with EMT features. In addition, EBV-related factors EBER and LMP1 were highly expressed and correlated strongly with CSCs and EMT characteristics in neoplastic spindle cells. Importantly, high proportion of spindle cells (≥20%) correlated significantly with various aggressive aspects including lymph node metastasis (P = 0.031) and local recurrence (P = 0.014). Patients with high proportion of spindle cells had poor survival (P = 0.004), though it was not an independent value. In conclusion, we demonstrate that spindle cells could be valuable morphological indicators of tumor progression and unfavorable prognosis of NPC. An integrated molecule-morphology model of NPC firstly constructed may shed significant light on the metastatic cascade and clinical relevance of patients.

The pathological roles of BART miRNAs in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a distinct type of head and neck cancer prevalent in south-east Asia and southern China, where it constitutes a significant health burden. Although the close association of NPC with Epstein-Barr virus (EBV) infection has been known for more than four decades, the exact role that EBV plays in the pathogenesis of this malignancy is still unclear. While NPC tumours are known to express a number of EBV-encoded proteins, they also express a large number of virus-encoded microRNAs (miRNAs), the most abundant of which are those encoded from the BamHI-A region of the viral genome: the so-called BART miRNAs. miRNAs are small non-coding mRNAs that negatively regulate the expression of various genes at the post-transcriptional level. Accumulating evidence suggests that miRNAs play important roles in tumourigenesis. Here, we review the role of EBV-encoded BART miRNAs in modulating apoptosis and host innate defence mechanisms and their contribution to NPC pathogenesis. The rationale and strategies for therapeutic targeting of BART miRNAs in EBV-infected NPC are also discussed.

Expression of bcl-2 and p53 proteins in nasopharyngeal carcinoma. Absence of correlation with the presence of EBV encoded EBER1-2 transcripts and latent membrane protein-1

Aims-To investigate the immunohistochemical expression of bcl-2 and p53 proteins in nasopharyngeal carcinomas in relation to the expression of the Epstein-Barr virus (EBV) encoded EBER messenger RNAs (mRNAs) and latent membrane protein-1 (LMP-1).Methods-Formalin fixed, paraffin wax embedded tissue from 44 nasopharyngeal carcinomas (NPCs) was stained by immunohistochemistry for p53, bcl-2 and LMP-1 proteins and by RNA in situ hybridisation for EBER mRNAs.Results-The tumours were divided histologically into 13 cases of keratinising squamous cell NPC (KNPC), 15 cases of non-keratinising squamous cell NPC (NKNPC) and 16 cases of undifferentiated NPC (UNPC). Bcl-2 expression was observed in five of 15 NKNPC cases and in six of 16 UNPC cases; p53 expression was observed in one of 13 KNPC, two of 15 NKNPC and four of 16 UNPC cases. EBER 1-2 transcripts were detected in five of 15 NKNPC and nine of 16 UNPC cases, while LMP-1 expression was observed in one of 16 UNPC cases. All 13 KNPCs were EBV and bcl-2 negative. No correlation was found between the presence of EBER 1-2 transcripts and the detection of bcl-2 or p53 proteins, or both, in NPC cells.Conclusions-The expression of bcl-2 and p53 proteins may be associated with the level of the tumour cell differentiation in NPC. In addition, in view of the important role of the bcl-2 protein in the inhibition of apoptosis, the expression of bcl-2 protein may contribute to tumour cell survival in a proportion of NPCs. Furthermore, in the light of previous findings that the p53 gene in most UNPCs is in the wild-type configuration, mechanisms other than mutation may be responsible for stabilisation of the p53 protein in UNPCs.

Critical role of p53 in histone deacetylase inhibitor-induced Epstein-Barr virus Zta expression

The tumor suppressor gene p53 plays a central role in the maintenance of normal cell growth and genetic integrity, while its impact on the Epstein-Barr virus (EBV) life cycle remains elusive. We found that p53 is important for histone deacetylase inhibitor-induced EBV lytic gene expression in nasopharyngeal carcinoma cells. Restoration of p53 in p53-null, EBV-infected H1299 cells augments the potential for viral lytic cycle initiation. Evidence from reporter assays demonstrated that p53 contributes to the expression of the immediate-early viral Zta gene. Further analysis indicated that the DNA-binding ability of p53 and phosphorylation of Ser392 may be critical. This study provides the first evidence that p53 is involved in the regulation of EBV lytic cycle initiation.

Epstein-Barr virus-associated epithelial and mesenchymal neoplasms

Epstein-Barr virus (EBV) is a ubiquitous human pathogen that usually maintains a harmonious relationship with its host. Rarely, this host-virus balance is perturbed, causing a diverse group of malignancies in both immunocompetent and immunosuppressed patients. In addition to its role in hematologic malignancies (Burkitt lymphoma, subsets of Hodgkin and T-cell lymphomas, posttransplant lymphomas), EBV has been implicated in both epithelial (undifferentiated nasopharyngeal carcinoma, a subset of gastric adenocarcinomas) and mesenchymal (EBV-associated smooth muscle tumor, inflammatory pseudotumor-like follicular dendritic cell tumor) neoplasms. This review will focus on EBV-associated epithelial and mesenchymal neoplasms.

The activation of p53 mediated by Epstein-Barr virus latent membrane protein 1 in SV40 large T-antigen transformed cells

The Epstein-Barr virus (EBV) encoded latent membrane protein 1 (LMP1) plays an important role in the carcinogenesis of nasopharyngeal carcinoma (NPC). The tumor suppressor p53 is an important transcription factor. The mutation of the p53 gene is the frequent alteration in most of tumors, but nearly 100% wild-type p53 gene is found in NPC biopsy. Here, our study testified that SV40 T-antigen transformed nasopharyngeal epithelial cells contained free, wild-type p53. Moreover, LMP1 regulated p53 both at transcriptional and translational level. Furthermore, the mechanism of p53 accumulation mediated by LMP1 from post-translational level-phosphorylation and ubiquitination were determined. Therefore, the effects of EBV LMP1 on p53 may potentially contribute to EBV-associated pathogenesis.

Latent membrane protein 1 of Epstein-Barr virus regulates p53 phosphorylation through MAP kinases

The Epstein-Barr virus (EBV) encoded latent membrane protein 1 (LMP1), an oncogenic protein, plays an important role in the carcinogenesis of nasopharyngeal carcinoma (NPC). Phosphorylation of p53 protein is likely to play the key role in regulating its activity. p53 protein accumulates but mutation of p53 gene is not common in NPC. The molecular mechanisms of p53 augmentation have not been completely elucidated. Here, the role of MAP kinases in the phosphorylation of p53 modulated by LMP1 was determined. p53 could be activated and phosphorylated clearly at Ser15, Ser20, Ser392, and Thr81 modulated by LMP1. Furthermore, LMP1-induced phosphorylation of p53 at Ser15 was directly by ERKs; at Ser20 and Thr81 by JNK, at Ser 15 and Ser392 by p38 kinase. The phosphorylation of p53 was associated with its transcriptional activity and stability modulated by LMP1. These results strongly suggest that MAP kinases have a direct role in LMP1-induced phosphorylation of p53 at multiple sites, which provide a novel view for us to understand the mechanism of the activation of p53 in the carcinogenesis of nasopharyngeal carcinoma.

Hepcidin, a key regulator of iron metabolism, is transcriptionally activated by p53

Hepcidin is an iron-regulatory protein that is upregulated in response to increased iron or inflammatory stimuli. Hepcidin reduces serum iron and induces iron sequestration in the reticuloendothelial macrophages - the hallmark of anaemia of inflammation. Iron deprivation is used as a defense mechanism against infection, and it also has a beneficial effect on the control of cancer. The tumour-suppressor p53 transcriptionally regulates genes involved in growth arrest, apoptosis and DNA repair, and perturbation of p53 pathways is a hallmark of the majority of human cancers. This study inspected a role of p53 in the transcriptional regulation of hepcidin. Based on preliminary bioinformatics analysis, we identified a putative p53 response-element (p53RE) contained in the hepcidin gene (HAMP) promoter. Chromatin immunoprecipitation (ChIP), reporter assays and a temperature sensitive p53 cell-line system were used to demonstrate p53 binding and activation of the hepcidin promoter. p53 bound to hepcidin p53RE in vivo, andthis p53RE could confer p53-dependent transcriptional activation. Activation of p53 increased hepcidin expression, while silencing of p53 resulted in decreased hepcidin expression in human hepatoma cells. Taken together, these results define HAMP as a novel transcriptional target of p53. We hypothesise that hepcidin upregulation by p53 is part of a defence mechanism against cancer, through iron deprivation. Hepcidin induction by p53 might be involved in the pathogenesis of anaemia accompanying cancer.

Linkage of TP53 codon 72 pro/pro genotype as predictive factor for nasopharyngeal carcinoma development

Genetic predisposition has been suggested as a cofactor for cancer aetiology and a polymorphism in TP53 codon 72 has been associated as a susceptibility factor for several cancers. Nasopharyngeal carcinoma is a rare neoplasia in western civilizations and genetic predisposition might play an important role in its development. We evaluated the linkage of the polymorphic variants (Arg/Pro) on TP53 codon 72 with nasopharyngeal cancer development in a case-control study with 392 individuals from a northern Portuguese population, including 107 patients with nasopharyngeal carcinoma and 285 healthy controls. This study revealed a three-fold risk for carriers of Pro/Pro genotype either against carriers of Arg/Arg (OR=2.62; 95% CI=1.10-6.30; P=0.016) or total Arg carriers (OR=2.67; 95% CI=1.21-5.90; P=0.012). Moreover, step-wise logistic regression analysis identified Pro/Pro genotype (OR=3.1; 95% CI=1.3-7.3; P=0.009), age >49 at diagnosis (OR=2.5; 95% CI=1.6-4.0; P<0.001) and male gender (OR=2.7; 95% CI=1.6-4.4; P<0.001) as predictive factors for the development of nasopharyngeal carcinoma. These results confirm the data from Asiatic populations suggesting that Pro/Pro genotype represents a stable risk factor for nasopharyngeal carcinoma development in Portugal and that TP53 codon 72 polymorphism can contribute as a genetic susceptibility marker, providing additional information to improve the knowledge about nasopharyngeal carcinoma aetiology.

Identification of differential proteins in nasopharyngeal carcinoma cells with p53 silence by proteome analysis

Although mutation of p53 tumor-suppressor gene is rare in nasopharyngeal carcinoma (NPC), NPC has a high frequency of overexpression of p53 protein. There seem to be complex mechanisms of inactivation and stabilization of p53 in NPC. To detect proteins associated with the function of p53 in high throughout screening, we succeeded in establishing p53 knockdown human NPC CNE2 cell line (CNE2sip53) using stable RNA interference, and compared the proteomic changes between CNE2sip53 and control cell line CNE2/pSUPER using two-dimensional gel electrophoresis. Twenty-two differentially expressed proteins between the two cell lines were identified by both matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and electrospray ionization tandem mass spectrometry, some of which are known to be associated with the p53 function (HSP27, hnRNP K, 14-3-3sigma, etc.), and others may be novel proteins associated with p53 function (eIF4B, TPT1, hnRNP H3, SFRS1 etc.). Furthermore, several differential proteins including HSP27, HSP70, GRP75 and GRP78 were verified as p53 interacting proteins in NPC by immunoprecipitation and Western blot analysis, and the suppression of HSP27 expression by HSP27 antisense oligonucleotides could decrease the p53 protein level. Our data suggest that these differential proteins may be associated with the function of p53 in NPC, and provide new clues to elucidate the mechanisms of inactivation and stabilization of p53 in NPC.

Prognostic Significance of the Epstein-Barr Virus, p53, Bcl-2, and Survivin in Nasopharyngeal Cancer

PURPOSE

Nasopharyngeal cancer (NPC) is a malignant epithelial carcinoma which is intimately associated with EBV. The latent presence of EBV affects the function of p53, Bcl-2, and survivin. We thus investigated the relationship between EBV status, p53, Bcl-2, and survivin in biopsy specimens from patients with primary NPC.

EXPERIMENTAL DESIGN

Archival formalin-fixed, paraffin-embedded NPC biopsies were evaluated in 80 patients treated with curative radiation from a single institution. The presence of EBV was determined using EBER in situ hybridization, whereas p53, Bcl-2, and survivin were assessed using immunohistochemistry.

RESULTS

The majority of NPC specimens in this patient cohort were EBER-positive (64 of 78, or 82%), which in turn, was significantly associated with ethnicity (P = 0.0007), and WHO subtype 2A/2B (P = 0.04). EBER-positive tumors were also associated with p53 (P = 0.002), Bcl-2 (P = 0.04), and nuclear survivin (P = 0.03) expression. Patients with EBER-positive NPC fared better, with a 10-year overall survival of 68% versus 48% for EBER-negative patients (P = 0.03). For nuclear survivin, patients with either low or high nuclear survivin fared worse than patients with intermediate survivin expression (P = 0.05), suggesting that there is an optimal proportion of survivin-expressing cells for best function and clinical outcome.

CONCLUSIONS

With an extended median follow-up time of 11.4 years, EBV status remains a strong predictor for overall survival in NPC. EBV-positive NPC has strong molecular associations with p53, Bcl-2, and survivin expression. Furthermore, we provide clinical data revealing the potentially dual nature of survivin in predicting clinical outcome.

Analysis of prognostic factors of nasopharyngeal carcinoma: impact of in situ hybridization for Epstein-Barr virus encoded small RNA 1

OBJECTIVES

To evaluate the impact of clinical, histopathological, and molecular biological parameters on the prognosis of nasopharyngeal carcinoma (NPC).

STUDY DESIGN AND SETTING

The clinical records of 48 patients with a diagnosis of NPC were retrospectively reviewed. In situ hybridization for Epstein-Barr virus encoded small RNA 1 (EBER-ISH) was applied for 30 paraffin-embedded specimens available. Prognostic factors of NPC were meticulously analyzed.

RESULTS

The EBER-ISH signal was shown to be highly significant as a favorable prognostic factor (P = 0.007). Although EBV was more commonly associated with Type III NPC, EBER-ISH-positive Type I-II NPC had also significantly better survival rate than EBER-ISH-negative Type I-II NPC (P = 0.036).

CONCLUSIONS

In addition to the WHO histopathological grade, the 1997 UICC staging, nodal status, and distant metastasis at presentation, the EBER-ISH signal was shown to be significant as a prognostic factor.

SIGNIFICANCE

This is the first report to describe the EBER-ISH as an independent prognostic factor of NPC regardless of histopathology.

EBM RATING

B-2b.

LMP1 signaling and activation of NF-kappaB in LMP1 transgenic mice

Transgenic mice expressing Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) under the control of an immunoglobulin heavy-chain promoter and enhancer develop lymphoma at a threefold higher incidence than LMP1-negative mice. In vitro, LMP1 activates numerous signaling pathways including p38, c-Jun N terminal kinase (JNK), phosphatidylinositol 3 kinase (PI3K)/Akt, and NF-kappaB through interactions with tumor necrosis receptor-associated factors (TRAFs). These pathways are frequently activated in EBV-associated malignancies, although their activation cannot be definitively linked to LMP1 expression in vivo. In this study, interactions between LMP1 and TRAFs and the activation of PI3K/Akt, JNK, p38, and NF-kappaB were examined in LMP1 transgenic mice. LMP1 co-immunoprecipitated with TRAFs 1, 2, and 3. Akt, JNK, and p38 were activated in LMP1-positive and -negative splenocytes as well as LMP1-positive and -negative lymphomas. Multiple forms of NF-kappaB were activated in healthy splenocytes from LMP1 transgenic mice, in contrast to healthy splenocytes from LMP1-negative mice. However, in both LMP1-positive and -negative lymphomas, only the oncogenic NF-kappaB c-Rel, was specifically activated. Similarly to EBV-associated malignancies, p53 protein was detected at high levels in the transgenic lymphomas, although mutations were not detected in the p53 gene. These data indicate that NF-kappaB is activated in LMP1-positive healthy splenocytes; however, NF-kappaB c-Rel is specifically activated in both the transgenic lymphomas and in the rare lymphomas that develop in negative mice. The LMP1-mediated activation of NF-kappaB may contribute to the specific activation of c-Rel and lead to the increased development of lymphoma in the LMP1 transgenic mice.

Epstein-Barr virus and cancer

EBV was the first human virus to be directly implicated in carcinogenesis. It infects >90% of the world's population. Although most humans coexist with the virus without serious sequelae, a small proportion will develop tumors. Normal host populations can have vastly different susceptibility to EBV-related tumors as demonstrated by geographical and immunological variations in the prevalence of these cancers. EBV has been implicated in the pathogenesis of Burkitt's lymphoma, Hodgkin's disease, non-Hodgkin's lymphoma, nasopharyngeal carcinoma, and lymphomas, as well as leiomyosarcomas arising in immunocompromised individuals. The presence of this virus has also been associated with epithelial malignancies arising in the gastric region and the breast, although some of this work remains in dispute. EBV uses its viral proteins, the actions of which mimic several growth factors, transcription factors, and antiapoptotic factors, to usurp control of the cellular pathways that regulate diverse homeostatic cellular functions. Recent advances in antiviral therapeutics, application of monoclonal antibodies, and generation of EBV-specific CTLs are beginning to show promise in the treatment of EBV-related disorders.

Absence of p53 alterations in nasopharyngeal carcinoma Spanish patients with Epstein-Barr virus infection

The objective of this study was to analyse the relationships between the Epstein-Barr virus (EBV) infection and the molecular abnormalities of the p53 oncoprotein in the nasopharyngeal carcinoma (NPC). Fifty-five NPC paraffin samples from a group of Spanish patients with EBV demonstrated presence by nested-PCR and non-isotopic in situ hybridisation, were analysed for p53 expression using immunohistochemistry. The positive samples by immunohistochemistry were studied for p53 gene alterations in the exon 5 by single strand conformation polymorphism (SSCP). Among the 55 specimens, 14 (25.5%) showed expression of p53 protein. All these positive samples corresponded to the late stage of the tumour. Of the 14 samples, p53 gene alterations were found only in three cases using SSCP. These results indicate that the p53 mutations are an infrequent event in NPC in Spanish patients needing exogenous factors as the EBV infection for the development of this malignancy.

Epstein-Barr virus-associated carcinomas: facts and fiction

The Epstein-Barr virus (EBV) is associated with several human tumours including lymphoid and epithelial malignancies. Most EBV-associated tumours are rare or occur at higher incidence only in certain geographical regions. The recently reported detection of EBV in gastric, breast, and hepatocellular carcinomas raises the possibility of involvement of the virus in the pathogenesis of common cancers. This article reviews the evidence linking EBV infection to epithelial tumours. It is concluded that at present, there is no convincing evidence to suggest that breast carcinoma and hepatocellular carcinoma are EBV-associated tumours.

Molecular pathology parameters in human nasopharyngeal carcinoma

BACKGROUND

To derive a better understanding of the biologic behavior of nasopharyngeal carcinoma (NPC), the authors evaluated a number of molecular variables to address the hypothesis that p53 dysfunction in NPC is associated with Epstein-Barr virus (EBV), increased tumor angiogenesis, lower likelihood of apoptosis, and poorer clinical outcome.

MATERIALS

The biopsy samples from 87 NPC patients were obtained and sections were made to detect EBV, using in-situ hybridization; the authors used immunohistochemistry to assess p53, p21(WAF1/CIP1) expression, and microvessel density count (MVD). In situ end labelling was used to evaluate apoptosis and necrosis. Analyses were conducted on the association between each of these variables as well as clinical outcome, including survival and local control.

RESULTS

There was a highly significant association between EBV-encoded RNA (EBER) positivity with p53 over-expression in that only 1 out of 32 p53 over-expressing tumors was EBER negative, as opposed to 19 out of 48 p53 negative tumors being EBER negative (P = 0.001). In addition, EBER positivity was highly associated with World Health Organization (WHO) type 3 NPC, Asian/Chinese ethnicity, a lower apoptotic index, and p21 over-expression. p53 over-expression was associated with a higher MVD count. Controlling for age and nodal status, EBER positivity was associated with both improved overall survival (P = 0.02), and disease-free survival (P = 0.04). In contrast, the presence of tumor necrosis was associated with an inferior local control (P = 0.03).

CONCLUSION

p53 protein was over-expressed in approximately one third of NPC samples in the current study, and this correlated significantly with the presence of EBER. Epstein-Barr virus status was also associated with WHO type 3 NPC, Asian/Chinese ethnicity, and induction of p21. The presence of EBV appeared to predict for improved survival, the mechanism of which remains to be elucidated in this biologically complex disease.

Association of p53 and BCL-2 expression with Epstein-Barr virus infection in the cancers of head and neck

BACKGROUND

Reports that have both evaluated the site-specific Epstein-Barr virus (EBV) infection and compared it with the expression of the EBV-related proto-oncogenes and tumor suppressor genes in the various cancers of head and neck are scarce.

METHODS

Thirty-eight nasopharyngeal carcinoma (NPC) cases, 32 oropharyngeal or hypopharyngeal carcinoma (OPC/HPC) cases, and 93 laryngeal carcinoma (LC) cases were evaluated with in situ hybridization on EBV-encoded small RNA (EBER) and immunohistochemical assessments of the p53, bcl-2, and epidermal growth factor receptor (EGFR) by use of formalin-fixed paraffin-embedded tissue array slides.

RESULTS

The expression of viral EBERs was observed in more than two thirds (71.1%) of the NPC cases. In contrast, only 1 case of OPC and none of the HPC or LC cases exhibited EBV positivity. In the nonkeratinizing NPC, the EBV positivity was significantly associated with both frequent p53 overexpression (p =.033) and bcl-2 expression (p =.001). In the EBV-positive nonkeratinizing NPC, a correlation between p53 overexpression and the tumor infiltration lymphocyte (TIL) density was noted (p =.012).

CONCLUSIONS

A site-specific expression of viral EBER was demonstrated in the head and neck cancers, which suggests an important role for both p53 and bcl-2 in the carcinogenesis of an EBV-infected NPC. The correlation between p53 overexpression and the TIL density in the EBV-infected NPC suggests that the product of a lymphoepithelial interaction, such as A20, can induce a dysfunctional p53 protein.

Expression of p53 tumor suppressor gene in adenoid cystic and mucoepidermoid carcinomas of the salivary glands

Seventeen adenoid cystic carcinomas (ACCs) and 27 mucoepidermoid carcinomas (MECs) occurring in the salivary glands were analyzed for p53 tumor suppressor gene alteration (exons 5-8) and protein expression. The cell proliferation activity was also examined by Ki-67 immunohistochemistry. The p53 alterations were detected in three samples (17.6%) of ACC and in four samples (14.8%) of MEC, and were only found in carcinomas arising in the minor salivary glands. The occurrence of the p53 gene alteration is less frequent in ACC and MEC than that in other kinds of tumors, and therefore does not seem to play a critical role in the course of the tumorigenesis in ACC and MEC. All ACC samples arising from the minor salivary glands exhibiting p53 gene alterations showed recurrence/metastasis, thus suggesting a poor outcome of these patients. All ACCs and three out of four MECs samples with p53 gene alterations showed the lowest degree of p53 immunostaining ratio, thus suggesting that no correlation exists between the p53 gene alterations and the p53 immunostaining in these salivary gland carcinomas. No significant relationship was demonstrated between the immunostaining ratio of either p53 or Ki-67 and the morphological growth pattern or patient clinical course in the ACC samples. The p53 immunopositivity in MEC correlated to the histological grade. The Ki-67 immunostaining ratio was also significantly related to the histological grade and the clinical course in MEC.

Epstein-Barr virus infection in the pathogenesis of nasopharyngeal carcinoma

The association of nasopharyngeal carcinoma (NPC) with the Epstein-Barr virus (EBV) was firmly established as early as 1973. Nevertheless, the role for the virus in the pathogenesis of NPC is still controversial. In this article, the evidence implicating EBV in the development of NPC is reviewed, focusing on the cellular site of EBV persistence, the association of the virus with different NPC histotypes, the tumour cell phenotype in the context of viral latent gene expression, and the possible role of the lymphoid stroma.

Epstein-Barr virus in gastric carcinomas with lymphoid stroma

AIMS

To clarify the relationship between the Epstein-Barr virus (EBV) and gastric carcinoma with lymphoid stroma (GCLS) in Koreans, and to characterize the EBV-positive GCLS.

METHODS AND RESULTS

EBV infection was examined using EBER in-situ hybridization and polymerase chain reaction in 45 cases of GCLS among Koreans, and in 292 consecutive cases of gastric carcinomas without lymphoid stroma (non-GCLS) as controls. EBV infection was found in 30 tumours (67%) of GCLS and 10 tumours (3.4%) of non-GCLS (P < 0.05). EBV-positive GCLS was more prevalent in males, poorly differentiated histological type and diffuse type in Lauren's classification, and tended to be located more in the middle third of the stomach than EBV-negative GCLS (P < 0.05). p53 overexpression was observed in 22% of GCLS (17% of EBV-positive GCLS and 33% of EBV-negative GCLS), and 34% of non-GCLS (EBV-positive GCLS vs. non-GCLS: P = 0.056). The survival of the patient with GCLS was not correlated with EBV infection or p53 immunoexpression (follow-up period: 11-97 months).

CONCLUSIONS

GCLS in Koreans is strongly associated with EBV infection. The prognosis in GCLS is not dependent upon either the status of EBV infection or the status of p53 immunoexpression.

Epstein-Barr Virus-Associated Cholangiocarcinoma with Lymphoepithelioma-Like Component

We report the case of a 19-year-old woman who presented with a hepatic mass without cirrhosis. Light microscopy revealed a cholangiocarcinoma having both well-differentiated adenocarcinoma and lymphoepithelioma-like undifferentiated carcinoma components. By immunohistochemistry, the tumor showed strong and diffuse expression for cytokeratin AE1, 5D3, and CK22. The tumor cells were positive for p53 protein (more than 75% of the cells) but negative for bcl-2 and LMP1. Abundant Epstein-Barr virus EBER (1/2) oligonucleotides were detected in both tumor components, but not in the lymphoid stroma or the nontumor liver. To the best of our knowledge, this is the third report of an Epstein-Barr virus-associated primary hepatobiliary adenocarcinoma with lymphoepithelioma-like component. Int J Surg Pathol 8(4):347-351, 2000

High level expression of deltaN-p63: a mechanism for the inactivation of p53 in undifferentiated nasopharyngeal carcinoma (NPC)?

Undifferentiated nasopharyngeal carcinoma (NPC) is an epithelial malignancy that is consistently associated with Epstein-Barr virus (EBV) but which very rarely has p53 gene mutations in primary tumours. Since the tumour suppressor p53 is mutated in most human cancers or the wild type protein is inactivated in a significant number of the remainder, here we have investigated cellular factors that could compromise p53 function in primary NPC. Twenty-five primary tumours were judged to carry only wild type p53 by SSCP analysis of all exons and sequence determination of exons 4-9. Only one tumour was found to express significant levels of hMdm2 and in 24/25 there were no detectable mutations or deletions in exons 1beta and 2 of the p14(ARF) gene. However, immunohistochemistry consistently revealed that all the tumour cells express substantial amounts of the p53-related protein p63. Semi-quantitative RT-PCR analysis of mRNA from tumour biopsies showed that the dominant species expressed was invariably the truncated deltaN-isotype. Since this can block p53-mediated transactivation, it is potentially a dominant-negative isoform. In normal nasopharyngeal epithelium the distribution of p63 was restricted to the proliferating basal and suprabasal layers. We suggest that deltaN-p63 is a good candidate as a suppressor of wild type p53 function in these tumours and also that it may prove to be a valuable diagnostic marker for undifferentiated NPC.

Epstein-Barr virus-associated gastric carcinomas: relation to H. pylori infection and genetic alterations

BACKGROUND & AIMS

The association of Epstein-Barr virus (EBV) and gastric carcinomas (GCs) has been shown to vary among different populations and certain histological subtypes. Few studies have addressed the status of Helicobacter pylori infection and genetic alterations in these EBV-positive or -negative GCs.

METHODS

Eleven gastric lymphoepithelioma-like carcinomas (LELCs) and 139 cases of common non-LELCs were evaluated for the presence of EBV DNA using polymerase chain reaction (PCR) and RNA in situ hybridization. H. pylori infection was determined by anti-H. pylori immunoglobulin G in preoperative sera. Immunostaining for p53, c-erbB-2, and E-cadherin was performed. Microsatellite instability was analyzed by PCR using 10 primers.

RESULTS

EBV was detected in 11 (100%) LELCs and in 19 (13.7%) of 139 common GCs. Compared with EBV-negative GCs, gastric LELCs tended to have a relatively higher frequency of proximal location, diffuse histological subtype, p53 overexpression, and reduced E-cadherin expression but a lower frequency of lymph node metastasis, previous H. pylori infection, and c-erbB-2 overexpression. In contrast, no significant difference of clinicopathologic and genetic profiles was observed between EBV-positive non-LELC GCs and EBV-negative GCs. No correlation of microsatellite instability was found among these 3 subsets of GCs.

CONCLUSIONS

Dissecting clinicopathologic characteristics and infection status of EBV and H. pylori provide additional evidence of etiological and genetic heterogeneity for GC. Distinct clinicopathologic and genetic pathways exist in gastric LELCs, in which EBV may play a more important role than H. pylori infection.

A functional investigation of tumor suppressor gene activities in a nasopharyngeal carcinoma cell line HONE1 using a monochromosome transfer approach

Monochromosome transfers of selected chromosomes into a nasopharyngeal carcinoma (NPC) cell line were performed to determine if tumor suppressing activity for NPC mapped to chromosomes 9, 11, and 17. Current information from cytogenetic and molecular allelotyping studies indicate that these chromosomes may harbor potential tumor suppressor genes vital to NPC. The present results show the importance of CDKN2A on chromosome 9 in NPC development. There was no functional suppression of tumor development in nude mice with microcell hybrids harboring the newly transferred chromosome 9 containing an interstitial deletion at 9p21, whereas transfection of CDKN2A into the NPC HONE1 cells resulted in obvious growth suppression. Whereas intact chromosome 17 transfers into HONE1 cells showed no functional suppression of tumor formation, chromosome 11 was able to do so. Molecular analysis of chromosome 11 tumor segregants indicated that at least two tumor suppressive regions mapping to 11q13 and 11q22-23 may be critical for the development of NPC.

Epstein-Barr virus and gastric carcinoma in Western patients: comparison of pathological parameters and p53 expression in EBV-positive and negative tumours

AIMS

The presence of Epstein-Barr virus (EBV) was studied in 56 gastric carcinomas from Western patients by in-situ hybridization for EBV-encoded RNAs (EBER). EBV-positive and negative carcinomas were compared for various pathological parameters including p53 overexpression.

METHODS AND RESULTS

EBERs transcripts were detected in seven cases overall: four cases of 52 conventional carcinomas (7. 7%) and three cases of four gastric carcinomas with lymphoid stroma (75%). EBER positivity was diffuse in five cases and restricted to a localized area of the tumour in two cases of conventional carcinoma. A monoclonal EBV genomic pattern was demonstrated in the case tested by Southern blot analysis. By immunohistochemical analysis, neither EBV latent or lytic cycle proteins nor C3d/EBV receptor were expressed by neoplastic cells. EBER positivity was significantly correlated with prominent lymphoid reaction (P = 0.0002) which was associated with numerous PS100-positive dendritic cells and with HLA-DR expression by tumour cells (P = 0.03). p53 immunoreactivity in more than 30% of tumour cells was detected in 25 out 49 EBV-negative cases and was absent in EBV-positive cases except in one case with focal EBER-positivity.

CONCLUSIONS

Focal staining for EBER is an unusual finding in the setting of gastric carcinoma and these results suggest that there might be two types of EBV-associated gastric carcinoma in which the viral infection will play a different role. The presence of a stromal lymphoid reaction which is strongly correlated with EBV positivity, is associated with antigen-presenting ability by HLA-DR-positive tumour cells or abundant dendritic cells. The function of p53 appears preserved in all EBV-associated carcinomas except in one case with focal EBER expression whereas the immunohistochemical pattern of p53 is suggestive of a mutational phenomenon in 51% of EBV-negative cases.

Epidemiological research into nasopharyngeal carcinoma in the Chubu region of Japan

Although patient death due to nasopharyngeal carcinoma (NPC) is increasing, few epidemiological analyses of NPC in Japan have been conducted since Sawaki's report in 1979. To determine the current incidence of NPC in Japan we examined NPC case in the Chubu area from 1986 to 1995. The leaders and reporting representatives of all otorhinolaryngological groups in the area were asked for their support of this epidemiological research. A total of 607 cases (445 male and 162 female NPC patients) were analyzed epidemiologically, histologically, serologically and clinically in this study. The incidence of NPC gradually increased with age. The mean age of the patients was 54.1 years. The age-standardized annual incidence in the Chubu region was 0.28 per 10(5) persons per year. The incidence in prefectures bordering Japan Sea (0.36) was significantly higher than that of prefectures facing the Pacific Ocean (0.21, P<0.05). On the basis of World Health Organization (WHO) histological criteria, 12%) of the cases were classified as WHO I, 54% as WHO II and 34% as WHO III. As for tumor origin, in 58% of the cases it originated posterosuperiorly, in 32% laterally and in 1% inferiorly. Tumor staging showed 4% to belong to stage I, 9% to stage II, 15% to stage III and 72% to stage IV. The positive rates of serum titers of the antibodies to Epstein Barr virus

Association of Epstein-Barr virus infection with p53 protein accumulation but not bcl-2 protein in nasopharyngeal carcinoma

AIMS

The aim of this study was to investigate the association of Epstein-Barr virus (EBV) infection with status of p53 protein expression in nasopharyngeal carcinoma (NPC). The expression of EBV gene and gene product, p53 protein and bcl-2 protein in NPC was histopathologically studied.

METHODS AND RESULTS

In-situ hybridization using oligonucleotide probe to EBV-encoded small RNAs (EBERs) and immunohistochemistry using monoclonal antibodies against EBV latent membrane protein 1 (LMP1), p53 protein and bcl-2 proteins were performed in 56 primary NPCs. EBERs were detected in 46 (82%) cases and LMP1 in 17 (30%) cases. While 30 of 32 (94%) cases in differentiated nonkeratinizing carcinoma (NKC, WHO type 2) and 16 of 17 (94%) cases in undifferentiated carcinoma (UC, WHO type 3) showed EBERs expression, neither five cases of keratinizing squamous cell carcinoma (KSCC, WHO type 1) nor two cases of adenocarcinoma showed EBERs. bcl-2 protein was detected in 50 (89%) cases, but its expression did not depend on expression of LMP1. p53 protein was detected in 31 (55%) cases, and there was a correlation between expression of EBERs and p53 protein (P < 0.05) but not between LMP1 and p53 protein.

CONCLUSION

In this study, close association of NKC and UC but not KSCC with the latent infection with EBV was demonstrated. The induction of bcl-2 protein by LMP1, as shown in vitro, was not demonstrated. The association between overexpression of p53 protein and the presence of EBV suggests that some EBV-encoded protein, which may be different from LMP1, may play a role for nuclear accumulation of p53 protein.

p53 inactivating mutations in Chinese nasopharyngeal carcinomas

Previously a low frequency of p53 mutations was detected in nasopharyngeal carcinoma (NPC) using molecular techniques to screen for mutations, yet immunohistochemical staining revealed a high frequency of p53 aberrant proteins. These findings might be attributed to the occurrence of p53 mutations outside the common hot spots and/or the inactivation of the protein through interactions with cellular or viral proteins. Using a previously established simple and sensitive p53 yeast functional assay, we blindly screened 25 nasopharyngeal biopsies for p53 mutations from exons 4 to 11. p53 was mutated in 27.3% of NPC specimens and in 0% of the nasopharyngeal biopsies from patients with non-malignant diseases. Two p53 mutations were detected in exon 7 and two were detected in exon 8. Interestingly, the exon 8 mutations observed in NPC lie in codons which appear to be hot spots for mutations in other head and neck cancers.

Epstein-Barr virus expression within keratinizing nasopharyngeal carcinoma

Three stages of maturation can be seen in keratinizing nasopharyngeal carcinomas. These stages are similar morphologically to basal cells, intermediate and superficial squamous cells seen in normal squamous epithelium. Taking advantage of such a diverse tumour cell population, 10 keratinizing nasopharyngeal carcinoma (NPC) were examined by in situ hybridization for the presence of latent Epstein-Barr Virus (EBV) using EBV encoded RNAs (EBERs) and by immunohistology for the presence of EBV early antigen-diffuse (EA-D) and the 350/220 kd membrane glycoprotein of the EBV. The basal cell-like tumour cells are mainly infected latently with the virus; viral replication was found in isolated intermediate squamous cells, whilst superficial squamous cells are largely depleted of all the viral markers. We used a control series of nonkeratinizing nasopharyngeal carcinomas composed of undifferentiated and poorly differentiated tumour cells and EBV latency was present in these tumours. Viral replication was detected by RT-PCR, in the undifferentiated tumours but viral replication was not seen by immunohistology. The possible relationship between EBV life cycle in these tumours and tumour cell differentiation is discussed in the light of these findings.

Regulation of IL-6 Signaling by p53: STAT3- and STAT5-Masking in p53-Val135-Containing Human Hepatoma Hep3B Cell Lines

The influence of p53 on cytokine-triggered Janus kinase-STAT signaling was investigated in human hepatoma Hep3B cell lines engineered to constitutively express the temperature-sensitive Val135 mutant of p53. In comparison to the parental p53-free Hep3B cells, these p53-Val135-containing Hep3B cell lines displayed a reduced response to IL-6 at the wild-type-like p53 temperature (32.5°C). In these cells, IL-6 induced a marked reduction in the immunologic accessibility of cytoplasmic and nuclear STAT3 and STAT5 within 20 to 30 min that lasted 2 to 4 h (STAT-masking) provided that the cells had been previously cultured at 32.5°C for at least 18 to 20 h. The onset of IL-6-induced STAT-masking required protein tyrosine kinase, protein tyrosine phosphatase, proteasomal, phospholipase C, and mitogen-activated protein kinase kinase 1 activities. The maintenance of IL-6-induced STAT-masking was dependent on continued signaling through the phosphatidylinositol-dependent phospholipase C pathway. Despite a reduction in IL-6-induced STAT3 DNA binding activity in the nuclear compartment during STAT-masking, there was increased and prolonged accumulation of tyrosine-phosphorylated STAT3 in both the cytoplasmic and nuclear compartments, indicating that the capacity of tyrosine-phosphorylated STAT3 to bind DNA was reduced during STAT-masking. Thus, IL-6-induced STAT-masking, as dramatically evident on immunomicroscopy, is a visible consequence of a novel cellular process by which a p53-Val135-induced gene product(s) regulates the association of masking protein(s) with and the DNA-binding capacity of STAT3.

Comparative analysis of Epstein-Barr virus (EBV) detection by nested-PCR and non-isotopic in situ hybridization in nasopharyngeal carcinoma (NPC)

The aims of this study were two-fold: first, to assess the relative diagnostic performance of non-isotopic in situ hybridization (ISH) and the nested polymerase chain reaction (nested-PCR) applied to Epstein-Barr virus (EBV) detection in a series of 55 unselected nasopharyngeal carcinoma (NPC) cases and, secondly, to correlate these data with histopathological classification. Our study shows that in 76.36% of NPC cases positive nuclear signals were observed using EBV-ISH. Overall, EBV-ISH positivity varied according to histological type, in that undifferentiated carcinomas showed a higher proportion of positive cases than differentiated cell carcinomas, although ISH results do not show significant differences in relation to histological types when employing two different schemes (WHO and Micheau). However, in adequate quality DNA samples (54 NPC cases), EBV-DNA was detected in 100% of cases using a nested-PCR, supporting the previous view that all histological types of NPC are in reality variants of EBV-infected neoplasia. ISH-negative cases probably reflect a lower sensitivity than PCR, particularly when a small number of viral copies are present, as well as a variable technical effectiveness for detected EBV, independent of the NPC histological type.

Epstein-Barr virus infection is associated with p53 accumulation in nasopharyngeal carcinoma

Eighty-three cases of nasopharyngeal carcinoma were evaluated for the presence of Epstein-Barr virus (EBV) infection in tumor cells by in situ hybridization to EBER1 transcripts, and for p53 expression by immunostains using the D07 antibody which detects native and mutant forms of the p53 protein. A highly significant association was found between EBV infection and p53 overexpression (P = .0004), with 77% of cases coexpressing both markers. This newly discovered association suggests that EBV is not an innocent bystander with respect to p53 accumulation. One possible mediator of the interaction between EBV and p53, viral BZLF1, was not colocalized with p53 in these tumors, suggesting that BZLF1 is not the factor responsible for p53 accumulation. From an epidemiological standpoint, this series of cancers represents an international cohort in which cases from an endemic part of the world (Hong Kong) were examined alongside cases from the United States, where the disease is 50-fold less prevalent. The cancers from Hong Kong tended to be less differentiated and more frequently associated with EBV, suggesting that biological differences might underlie epidemiological variations in tumor prevalence. Finally, we examined 18 potential premalignant lesions of the surface epithelium of the nasopharynx. Although our numbers are small, our data suggest that p53 accumulation might precede EBV infection in the transition from metaplasia to carcinoma in situ. Further studies are needed to dissect the stepwise progression of nasopharyngeal carcinogenesis.

Detection of Epstein-Barr virus transcripts in anaplastic large-cell lymphomas by mRNA in situ hybridization

Anaplastic large-cell lymphoma (ALCL) is a recently proposed subset of non-Hodgkin's lymphoma. To determine whether Epstein-Barr virus (EBV) is associated with this lymphoma, we performed mRNA in situ hybridization on seven cases of ALCL using a probe consisting of an RNA sequence complementary to the transcripts of BamHIW fragment of the EBV genome. We detected BamHIW transcripts of EBV in the majority of atypical large cells of all cases of ALCL, but in none of three cases of lymphoblastic and small lymphocytic lymphomas. Furthermore, we detected latent membrane protein-1 (LMP1) in two cases of ALCL by means of immunofluorescence and immunoperoxidase stainings. These findings suggest that EBV is involved in the neoplastic transformation for ALCL as in the case of Hodgkin's disease, which shares several clinicopathologic features with ALCL.

The association of squamous cell carcinomas of the nasopharynx with Epstein-Barr virus shows geographical variation reminiscent of Burkitt's lymphoma

Nasopharyngeal carcinoma (NPC) is rare in most parts of the world but occurs with high incidence in certain regions, such as South-East Asia. Two major histological types of NPC are recognized, non-keratinizing carcinoma and squamous cell carcinoma. Non-keratinizing NPCs, which include undifferentiated NPC, are invariably associated with Epstein-Barr virus (EBV) infection, regardless of the geographical or ethnic origin of the patients. By contrast, conflicting results have been published concerning a possible association of squamous cell NPC with the virus. To address this question, squamous cell NPCs have been collated from an area where NPC is endemic, Hong Kong, and from two regions where NPC occurs with a lower incidence, Chengdu, PR China, and Birmingham, United Kingdom. In situ hybridization for the detection of the small EBV-encoded nuclear RNAs (EBERs) demonstrated that all 22 cases from Hong Kong were EBV-positive. By contrast, EBV was detectable in 7 of 19 cases from central China, and in 3 of 7 cases from the U.K. Expression of the virus-encoded latent membrane protein 1 (LMP1) was detected in 3 of 32 EBV-positive squamous cell NPCs. These results indicate that the association of squamous cell NPCs with EBV shows geographical variability in a manner which is reminiscent of the situation encountered in Burkitt's lymphoma. This suggests that squamous cell NPCs are a pathogenetically heterogeneous group of tumours distinct from non-keratinizing NPCs.

Analysis of bcl-2 expression in normal, inflamed, dysplastic nasopharyngeal epithelia, and nasopharyngeal carcinoma: association with p53 expression

To further characterize bcl-2 expression in nasopharyngeal carcinoma (NPC), the authors analyzed bcl-2 expression immunohistochemically in biopsy specimens from 101 cases of NPC, of which 65 had the component of normal nasopharyngeal epithelium (NPE), 24 with dysplastic lesions adjacent to carcinoma, and 14 with both primary and metastatic lesions. An additional 25 nasopharyngeal biopsies of NPE from patients with chronic inflammation of nasopharynx were also included. The percentage of detectable bcl-2 expression shown in NPC (80%) and adjacent dysplastic lesions (71%) was significantly higher than in adjacent NPE (37%) and NPE from patients with chronic inflammation of the nasopharynx (30%) (P < .05). In both normal and inflamed NPE, the detectable bcl-2 expression was restricted to the basal cells; however, in dysplastic lesions, the bcl-2 staining distribution was increased with the dysplastic cell layers, and in entire layers of epithelium in severe dysplasia or carcinoma in situ. In addition, the staining intensity of bcl-2 in carcinomas and adjacent dysplastic lesions was generally stronger than that of adjacent NPE. These observations suggest that the expression of bcl-2 in dysplasia and carcinoma is enhanced relative to that of adjacent NPE. Enhanced bcl-2 expression to prevent apoptosis seems to occur from the early stages and may play an important role in the carcinogenesis of NPC. Furthermore, up to 77% of NPC with the coexpression of bcl-2 and p53 was observed and suggested that the association of bcl-2 and p53 expression seems to occur from the early stages of the development of NPC. The overexpression of p53 protein in NPC suggests that the mutation of p53 gene or altered function of wild-type p53 protein may contribute to the pathogenesis. It is conceivable that the presence of both enhanced bcl-2 expression and altered p53 functions may play a crucial synergistic effect in the carcinogenesis of NPC.

Nasopharyngeal carcinoma, with emphasis on its relationship to Epstein-Barr virus

Nasopharyngeal carcinoma (NPC) is an epithelial tumor with a distinct geographic distribution and characteristic histologic appearance. It is rare in Europe and North America, but it is among the most common cancers in southern China. Genetic predisposition, environmental factors, and Epstein-Barr virus (EBV) all have been associated with the pathogenesis of this tumor. There is an increasing body of evidence that among all these factors, EBV appears to be the strongest and most consistently related factor. According to the current sensitive in situ hybridization methods for the detection of EBV-encoded small RNAs (EBER), almost 100% of cases of NPC, irrespective of their histologic subtypes, have demonstrable EBERs in the nuclei of the tumor cells. In this review paper, we discuss the predisposing genetic and environmental factors and the role of EBV in the pathogenesis of this tumor with particular emphasis on the role of EBV.

Detection of Epstein-Barr virus in nasopharyngeal carcinoma by in situ hybridization and polymerase chain reaction

The association of Epstein-Barr virus (EBV) with nasopharyngeal carcinoma (NPC) has been shown by various methods. The purpose of this study is to identify the most useful method to detect EBV in NPC. Both polymerase chain reaction (PCR) for EBV-DNA and in situ hybridization for EBV-encoded small RNAs (EBERs) were examined in formalin-fixed, paraffin-embedded NPC specimens. In situ hybridization was performed in 56 cases, and PCR for EBV-DNA was performed in 42 cases. EBV-DNA was detected in 0 of 3 keratinizing squamous cell carcinomas (KSCC), 22 of 24 nonkeratinizing carcinomas (NKC), all 13 undifferentiated carcinomas (UNPC), and 0 of 2 adenocarcinomas (AC). EBERs were detected in 0 of 5 KSCC, 30 of 32 NKC, 16 of 17 UNPC, and 0 of 2 AC. Among them, EBERs was detected in 35 of 42 cases in which PCR was also performed, 0 of 3 KSCC, 22 of 24 NKC, all 13 UNPC, and 0 of 2 AC, respectively. Both results were consistent in 40 of 42 cases. We conclude that both PCR and in situ hybridization are useful to detect EBV in NPC. In situ hybridization has a particular advantage because it can demonstrate the localization of EBV in neoplastic cells. In addition, close association of NKC and UNPC but not KSCC and AC with EBV is suggested.

Spontaneous human squamous cell carcinomas are killed by a human cytotoxic T lymphocyte clone recognizing a wild-type p53-derived peptide

A cytotoxic T lymphocyte (CTL) clone generated in vitro from the peripheral blood of a healthy HLA-A2-positive individual against a synthetic p53 protein-derived wild-type peptide (L9V) was shown to kill squamous carcinoma cell lines derived from two head and neck carcinomas, which expressed mutant p53 genes, in a L9V/HLA-A2 specific and restricted fashion. Thus, the normal tolerance against endogenously processed p53 protein-derived self-epitopes can be broken by peptide-specific in vitro priming. p53 protein-derived wild-type peptides might thus represent tumor associated target molecules for immunotherapeutical approaches.