Epstein-barr virus-positive gastric carcinoma has a distinct protein expression profile in comparison with epstein-barr virus-negative carcinoma

Improved survival of gastric cancer with tumour Epstein-Barr virus positivity: an international pooled analysis

BACKGROUND AND OBJECTIVE

About 9% of gastric carcinomas have Epstein-Barr virus (EBV) in the tumour cells, but it is unclear whether viral presence influences clinical progression. We therefore examined a large multicentre case series for the association of tumour EBV status with survival after gastric cancer diagnosis, accounting for surgical stage and other prognostic factors.

METHODS

We combined individual-level data on 4599 gastric cancer patients diagnosed between 1976 and 2010 from 13 studies in Asia (n=8), Europe (n=3), and Latin America (n=2). EBV positivity of tumours was assessed by in situ hybridisation. Mortality HRs for EBV positivity were estimated by Cox regression models stratified by study, adjusted for distributions of sex (71% male), age (mean 58 years), stage (52% tumour-node-metastasis stages III or IV), tumour histology (49% poorly differentiated, 57% Lauren intestinal-type), anatomic subsite (70% non-cardia) and year of diagnosis. Variations by study and continent were assessed using study-specific HRs for EBV positivity.

RESULTS

During median 3.0 years follow-up, 49% of patients died. Stage was strongly predictive of mortality, with unadjusted HRs (vs stage I) of 3.1 for stage II, 8.1 for stage III and 13.2 for stage IV. Tumour EBV positivity was 8.2% overall and inversely associated with stage (adjusted OR: 0.79 per unit change). Adjusted for stage and other confounders, EBV positivity was associated with lower mortality (HR, 0.72; 95% CI 0.61 to 0.86), with low heterogeneity among the study populations (p=0.2). The association did not significantly vary across patient or tumour characteristics. There was no significant variation among the three continent-specific HRs (p=0.4).

CONCLUSIONS

Our findings suggest that tumour EBV positivity is an additional prognostic indicator in gastric cancer. Further studies are warranted to identify the mechanisms underlying this protective association.

Epstein-Barr virus-encoded BARF1 promotes proliferation of gastric carcinoma cells through regulation of NF-κB

In Epstein-Barr virus (EBV)-infected gastric carcinoma, EBV-encoded BARF1 has been hypothesized to function as an oncogene. To evaluate cellular changes induced by BARF1, we isolated the full-length BARF1 gene from gastric carcinoma cells that were naturally infected with EBV and transfected BARF1 into EBV-negative gastric carcinoma cells. BARF1 protein was primarily secreted into culture supernatant and only marginally detectable within cells. Compared with gastric carcinoma cells containing empty vector, BARF1-expressing gastric carcinoma cells exhibited increased cell proliferation (P < 0.05). There were no significant differences in apoptosis, invasion, or migration between BARF1-expressing gastric carcinoma cells and empty vector-transfected cells. BARF1-expressing gastric carcinoma cells demonstrated increased nuclear expression of nuclear factor kappa B (NF-κB) RelA protein and increased NF-κB-dependent cyclin D1. The expression of p21(WAF1) was diminished by BARF1 transfection and increased by NF-κB inhibition. Proliferation of naturally EBV-infected gastric carcinoma cells was suppressed by BARF1 small interfering RNA (siRNA) (P < 0.05). Immunohistochemical analysis of 120 human gastric carcinoma tissues demonstrated increased expression of cyclin D1 and reduced expression of p21(WAF1) in EBV-positive samples versus EBV-negative gastric carcinomas (P < 0.05). In conclusion, the secreted BARF1 may stimulate proliferation of EBV-infected gastric carcinoma cells via upregulation of NF-κB/cyclin D1 and reduction of the cell cycle inhibitor p21(WAF1), thereby facilitating EBV-induced cancer progression.

Loss of P16 Protein Expression and Its Association with Epstein-Barr Virus LMP-1 Expression in Hodgkin's Lymphoma

Background

Expression of Epstein-Barr virus Latent Member Protein-1 (EBV LMP-1) and loss of P16 protein expression are documented in lymphoma, indicating a relationship between them, but this relationship is not clear and sometimes contradictory. Thus, this study was conducted to examine the relationship between the loss of P16 and EBV LMP-1 expression in Jordanian patients diagnosed with lymphoma.

Methods

Sections were made from archival formalin-fixed and paraffin-embedded blocks from 55 patients diagnosed with lymphoma. P16 expression and LMP-1 expression were detected by immunohistochemistry using monoclonal antibodies.

Results

In Hodgkin's Lymphoma (HL), the loss of P16 was higher in LMP-1 positive cases (61%) than LMP-1 negative cases (25%; P = 0.072). Conversely, in Non-Hodgkin's Lymphoma (NHL), none of LMP-1 positive samples showed loss of P16. Furthermore, among LMP-1 HL positive cases, the loss of P16 was more frequent in male (75%) than female (33%). Also, there was a significantly higher proportion of LMP-1 positive cases showing loss of P16 in HL (11:18), compared to those in NHL (0:8, P < 0.001), confirming a difference between HL and NHL, concerning the LMP-1/P16 relationship.

Conclusion

A trend for an association between loss of P16 and LMP-1 expression was observed in HL but not NHL patients. These findings suggest that there are molecular and clinical differences in the pathogenesis and development of different subtypes of lymphoma.

Epstein-barr virus infected gastric adenocarcinoma expresses latent and lytic viral transcripts and has a distinct human gene expression profile

BACKGROUND

EBV DNA is found within the malignant cells of 10% of gastric cancers. Modern molecular technology facilitates identification of virus-related biochemical effects that could assist in early diagnosis and disease management.

METHODS

In this study, RNA expression profiling was performed on 326 macrodissected paraffin-embedded tissues including 204 cancers and, when available, adjacent non-malignant mucosa. Nanostring nCounter probes targeted 96 RNAs (20 viral, 73 human, and 3 spiked RNAs).

RESULTS

In 182 tissues with adequate housekeeper RNAs, distinct profiles were found in infected versus uninfected cancers, and in malignant versus adjacent benign mucosa. EBV-infected gastric cancers expressed nearly all of the 18 latent and lytic EBV RNAs in the test panel. Levels of EBER1 and EBER2 RNA were highest and were proportional to the quantity of EBV genomes as measured by Q-PCR. Among protein coding EBV RNAs, EBNA1 from the Q promoter and BRLF1 were highly expressed while EBNA2 levels were low positive in only 6/14 infected cancers. Concomitant upregulation of cellular factors implies that virus is not an innocent bystander but rather is linked to NFKB signaling (FCER2, TRAF1) and immune response (TNFSF9, CXCL11, IFITM1, FCRL3, MS4A1 and PLUNC), with PPARG expression implicating altered cellular metabolism. Compared to adjacent non-malignant mucosa, gastric cancers consistently expressed INHBA, SPP1, THY1, SERPINH1, CXCL1, FSCN1, PTGS2 (COX2), BBC3, ICAM1, TNFSF9, SULF1, SLC2A1, TYMS, three collagens, the cell proliferation markers MYC and PCNA, and EBV BLLF1 while they lacked CDH1 (E-cadherin), CLDN18, PTEN, SDC1 (CD138), GAST (gastrin) and its downstream effector CHGA (chromogranin). Compared to lymphoepithelioma-like carcinoma of the uterine cervix, gastric cancers expressed CLDN18, EPCAM, REG4, BBC3, OLFM4, PPARG, and CDH17 while they had diminished levels of IFITM1 and HIF1A. The druggable targets ERBB2 (Her2), MET, and the HIF pathway, as well as several other potential pharmacogenetic indicators (including EBV infection itself, as well as SPARC, TYMS, FCGR2B and REG4) were identified in some tumor specimens.

CONCLUSION

This study shows how modern molecular technology applied to archival fixed tissues yields novel insights into viral oncogenesis that could be useful in managing affected patients.

Epstein-Barr virus-associated gastric carcinoma in Brazil: comparison between in situ hybridization and polymerase chain reaction detection

Epstein-Barr virus (EBV) has been associated with 10% of gastric carcinomas. The aim of this study was to determine the frequency of EBV in gastric carcinomas in Brazil assessed by in situ hybridization (ISH) and PCR, which would contribute to the characterization of the clinical and pathological aspects of EBV-associated gastric carcinomas. One hundred and ninety-two gastric carcinoma cases were collected at hospitals in two Brazilian states. Seventy-three out of 151 cases were PCR(+), while 11/160 cases were ISH(+). Nine out of eleven ISH(+) cases displayed a diffuse staining pattern and 2 out of 11 a focal pattern. Both techniques showed that the EBV(+) cases were characterized by their association with males, older patients, lower gastric region, intestinal type, advanced stage and poorly to moderately differentiated tumors. The concordance between the two techniques was 55.8% (Cohen's kappa index = 0.034). Four cases were ISH(+)/PCR(-), while 49 cases were PCR(+)/ISH(-). Only two cases showed stained lymphocytes by ISH and one of them was PCR(-). The observed discrepancy between the two techniques could not be explained just by the elevated accuracy of PCR. ISH(+)/PCR(-) carcinomas may be encountered if EBV is not present in the whole tumor tissue or if there are polymorphisms in the sequences of the viral genome amplified. On the other hand, the high frequency of PCR(+) results associated with the absence of ISH staining in lymphocytes and/or tumors cells suggests that the virus may be present in tumor cells or other cell types without expressing EBER1, the target of the ISH technique.

Infection of Epstein-Barr virus in a gastric carcinoma cell line induces anchorage independence and global changes in gene expression

Latent infection of EBV is linked to the development of multiple cancers that have distinct patterns of expression of viral proteins and microRNAs (miRNAs). In this study, we show that in vitro infection of a gastric epithelial cell line with EBV alters growth properties and induces growth in soft agar. The infected cells have high levels of expression of a large cluster of viral miRNAs, [the BamHI A rightward transcript (BART) miRNAs] and limited viral protein expression. Expression profile microarray analysis of this cell line revealed a large number of changes in cellular expression, with decreased expression of many genes. Inhibition of the trace-expressed levels of the viral oncoprotein, latent membrane protein 1, did not affect growth or alter the pattern of cellular expression. The expression changes are highly enriched for genes involved in cell motility and transformation pathways, suggesting these changes are important for the altered growth phenotype. Importantly, the transcripts decreased by microarray are significantly enriched in both experimentally and bioinformatically predicted BART miRNA targets. The absence of viral protein expression and the enrichment for viral miRNA targets in the modulated cell genes suggest that the BART miRNAs are major contributors to the transformed growth properties of the EBV-infected cells. The ability to affect cell growth through miRNA expression without viral protein expression would be a major factor in the development of cancer in individuals with functional immune systems.

Epstein-Barr virus-associated gastric carcinoma: a newly defined entity

Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVaGC) is a recently recognized entity, which is defined by the presence of EBV in the gastric carcinoma cells. EBVaGC represents about 10% of gastric carcinoma worldwide, and >80,000 patients are estimated to develop EBVaGC annually. EBVaGC shows some distinct clinicopathologic characteristics, such as male predominance, predisposition to the proximal stomach, and a high proportion in diffuse-type gastric carcinomas. Besides, EBVaGC also shows characteristic molecular abnormality, that is, global and nonrandom CpG-island methylation of the promoter region of many cancer-related genes, which causes downregulation of their expression. Moreover, EBVaGC has a relative favorable prognosis. The uniform presence of EBV-encoded small RNA in tumor cells but not in the surrounding normal epithelial cells, and the detection of monoclonal EBV episomes in EBVaGC, strongly suggests that EBV play an etiological role in gastric carcinogenesis. Therefore, EBVaGC should be regarded as a distinct entity of gastric carcinoma, although it only accounts for a relatively small fraction of total gastric carcinomas. In this review, the epidemiological and clinicopathologic features of EBVaGC and the genetic abnormalities of EBVaGC cell including chromosomal and epigenetic abnormalities are described. The roles of EBV in gastric carcinogenesis are discussed. We make an emphasis on the EBV latency pattern and genome polymorphisms as well as local immunity in EBVaGC. In addition, the treatment of EBVaGC is also briefly discussed. Taken together, this review aims to give the reader a full understanding of a newly defined entity of gastric carcinoma, EBVaGC.

Correlation between Epstein-Barr virus infection and tumor angiogenesis in patients with gastric carcinoma

AIM: To evaluate the characteristics of Epstein-Barr virus (EBV)-associated gastric cancer and to explore the correlation between EBV infection and tumor angiogenesis in patients with gastric carcinoma.

METHODS: EBV infection was examined by localizing EBV-encoded small RNAs (EBERs) using in situ hybridization. Tumor angiogenesis was evaluated by examining the expression of VEGF protein using immunohistochemistry and tissue microarray technique. The association of EBV infection with clinicopathological parameters, including age, gender, tumor type, lymph node metastasis, and tumor stage, was analyzed. The correlation of VEGF expression with lymph node metastasis and Lauren's classification was also analyzed.

RESULTS: Among 486 patients, 18 showed nuclear expression of EBV. EBV staining was seen only in tumor cells. 14 of 18 patients with EBV-associated gastric cancer had regional lymph node metastasis. Of note, metastatic tumor cells in all of the involved lymph nodes contained EBV. EBER-positive gastric carcinomas tended to have lymphoid stroma (17/18) and were mostly poorly differentiated type (P<0.05). There was no significant difference in TNM stage between EBV-positive and -negative carcinomas (P>0.05). The positive rate of VEGF protein expression was 28.2% (137/486). Angiogenesis was significantly associated with lymph node metastasis and TNM stage (both P<0.05). EBV infection was closely correlated with angiogenesis (r = 0.119, P = 0.009).

CONCLUSION: EBV is present exclusively in gastric cancer cells and tumor cells in all of the lymph nodes involved. EBV-positive gastric cancer has distinct clinicopathological features. Angiogenesis may be a good predictor of metastasis and prognosis of gastric carcinoma in patients with EBV-associated gastric cancer.

Association between Epstein-Barr virus infection and chemoresistance to docetaxel in gastric carcinoma

Epstein-Barr virus (EBV) is associated with human cancers such as nasopharyngeal carcinoma, Burkitt's lymphoma, Hodgkin's disease, and gastric carcinoma (GC). EBV is associated with about 10% of all GC cases globally. EBV-associated GC has distinct features from EBV-negative GC. However, it is still unclear if EBV infection has any effect on GC chemoresistance. Cell proliferation assay, cell cycle analysis, and active caspase Western blot revealed that the EBV-positive GC cell line (AGS-EBV) showed chemoresistance to docetaxel compared to the EBV-negative GC cell line (AGS). Docetaxel treatment increased expression of Bax similarly in AGS and AGS-EBV cell lines. However, Bcl-2 induction was markedly higher in AGS-EBV cells, after docetaxel treatment. Although docetaxel increased the expression of p53 to a similar extent in both cell lines, induction of p21 in AGS-EBV cells was lower than in AGS cells. Furthermore, expression of survivin was higher in AGS-EBV cells than in AGS cells following docetaxel treatment as well as at basal state. EBVlytic gene expression was induced by docetaxel treatment in AGS-EBV cells. The results suggest that EBV infection and lytic induction confers chemoresistance to GC, possibly by regulating cellular and EBV latent and lytic gene expression.

Determinants of Epstein-Barr virus-positive gastric cancer: an international pooled analysis

BACKGROUND

Meta-analyses of the published literature indicate that about 9% of gastric cancers contain Epstein-Barr virus (EBV), with consistent and significant differences by sex and anatomic subsite. This study aimed to identify additional determinants of EBV positivity and their joint effects.

METHODS

From 15 international populations with consistent laboratory testing for EBV, we pooled individual-level data for 5081 gastric cancer cases including information on age, sex, subsite, histologic type, diagnostic stage, geographic region, and period of diagnosis. First, we combined population-specific EBV prevalence estimates using random effects meta-analysis. We then aggregated individual-level data to estimate odds ratios of EBV positivity in relation to all variables, accounting for within-population clustering.

RESULTS

In unadjusted analyses, EBV positivity was significantly higher in males, young subjects, non-antral subsites, diffuse-type histology, and in studies from the Americas. Multivariable analyses confirmed significant associations with histology and region. Sex interacted with age (P=0.003) and subsite (P=0.002) such that male predominance decreased with age for both subsites. The positivity of EBV was not significantly associated with either stage or time period.

CONCLUSION

Aggregating individual-level data provides additional information over meta-analyses. Distinguishing histologic and geographic features as well as interactions among age, sex, and subsite further support classification of EBV-associated gastric cancer as a distinct aetiologic entity.

EBV-infection in cardiac and non-cardiac gastric adenocarcinomas is associated with promoter methylation of p16, p14 and APC, but not hMLH1

BACKGROUND

Epstein-Barr virus (EBV)-associated gastric carcinomas (GC) constitute a distinct clinicopathological entity of gastric cancer. In order to determine underlying distinct aberrant promoter methylation we tested cardiac and non-cardiac GC with regard to the presence of EBV.

METHODS

One hundred GC were tested by RNA-in situ hybridization for the presence of EBV by EBV-encoded small RNA (EBER). Aberrant promoter methylation was investigated by methylation-specific real-time PCR for p16, p14, APC and hMLH1. P16 protein expression was assessed by immunohistochemistry.

RESULTS

In our selected study cohort, EBER-transcripts were detected in 19.6% (18/92) of GC. EBV-positive GC revealed significantly more often gene hypermethylation of p16, p14 and APC (p<0.0001, p<0.0001 and p=0.02, respectively) than EBV-negative GC. The majority of GC with p16 hypermethylation showed a p16 protein loss (22/28). In contrast, no correlation between the presence of EBV and hMLH1 hypermethylation was found (p=0.7). EBV-positive GC showed a trend towards non-cardiac location (p=0.06) and lower stages (I/II) according to the WHO (p=0.05).

CONCLUSIONS

Hypermethylation of tumor suppressor genes is significantly more frequent in EBV-associated GC compared to EBV-negative GC. Our data add new insights to the role of EBV in gastric carcinogenesis and underline that EBV-associated GC comprise a distinct molecular-pathologic as well as a distinct clinicopathological entity of GC.

Epstein-Barr virus-specific methylation of human genes in gastric cancer cells

Background

Epstein-Barr Virus (EBV) is found in 10% of all gastric adenocarcinomas but its role in tumor development and maintenance remains unclear. The objective of this study was to examine EBV-mediated dysregulation of cellular factors implicated in gastric carcinogenesis.

Methods

Gene expression patterns were examined in EBV-negative and EBV-positive AGS gastric epithelial cells using a low density microarray, reverse transcription PCR, histochemical stains, and methylation-specific DNA sequencing. Expression of PTGS2 (COX2) was measured in AGS cells and in primary gastric adenocarcinoma tissues.

Results

In array studies, nearly half of the 96 human genes tested, representing 15 different cancer-related signal transduction pathways, were dysregulated after EBV infection. Reverse transcription PCR confirmed significant impact on factors having diverse functions such as cell cycle regulation (IGFBP3, CDKN2A, CCND1, HSP70, ID2, ID4), DNA repair (BRCA1, TFF1), cell adhesion (ICAM1), inflammation (COX2), and angiogenesis (HIF1A). Demethylation using 5-aza-2'-deoxycytidine reversed the EBV-mediated dysregulation for all 11 genes listed here. For some promoter sequences, CpG island methylation and demethylation occurred in an EBV-specific pattern as shown by bisulfite DNA sequencing. Immunohistochemistry was less sensitive than was western blot for detecting downregulation of COX2 upon EBV infection. Virus-related dysregulation of COX2 levels in vitro was not recapitulated in vivo among naturally infected gastric cancer tissues.

Conclusions

EBV alters human gene expression in ways that could contribute to the unique pathobiology of virus-associated cancer. Furthermore, the frequency and reversability of methylation-related transcriptional alterations suggest that demethylating agents have therapeutic potential for managing EBV-related carcinoma.

Epstein-Barr virus and gastric carcinoma

Epstein-Barr virus (EBV) has been accepted as an infective agent causing gastric carcinoma (GC). Epstein-Barr virus-associated GC, comprising nearly 10% of all cases of GC, is the monoclonal growth of EBV-infected epithelial cells, which express several EBV-latent genes (latency I program). Sequential events in the gastric mucosa could be traced from EBV infection of the pit cells to fully developed carcinomas by EBV encoded small RNA (EBER)-in situ hybridization. The histological features of the carcinoma consist of a lace pattern of carcinoma cells within the mucosa and the dense infiltration of lymphocytes and macrophages at the invasive site, which might be due to cytokines produced by neoplastic cells. The primary molecular abnormality in EBV-associated GC is global and non-random CpG island methylation in the promoter region of many cancer-related genes. The experimental system of recombinant EBV infection using GC cell lines demonstrated that viral latent membrane protein 2A (LMP2A) is responsible for the promotion of DNA methylation. LMP2A up-regulates cellular DNMT1 through the phosphorylation of STAT3, causing CpG methylation of a tumor suppressor gene, PTEN. DNA methylation in EBV-infected stomach cells may be due to overdrive of the cellular defense against foreign DNA, which eventually leads to the development of EBV-associated GC.

Host inflammatory response predicts survival of patients with Epstein-Barr virus-associated gastric carcinoma

BACKGROUND & AIMS

Lymphoepithelioma-like carcinoma (LELC) is a rare subtype of gastric carcinoma (GC) with a better survival rate than other GCs; most cases of LELC are associated with Epstein-Barr virus (EBV) infection. We investigated whether the survival advantage of LELC is related to the EBV infection itself or to associated inflammatory immune responses.

METHODS

From 1994 to 2008, 123 EBV-associated GCs were identified and compared with 405 EBV-negative GCs. EBV-associated GCs were subclassified, based on the pattern of host inflammatory immune responses, into 3 histologic subtypes: typical LELC (n = 53, 43.1%), Crohn's disease-like lymphocytic reaction (CLR) (n = 52, 42.3%), and conventional adenocarcinoma (n = 18, 14.6%). Patients with curatively resected EBV-negative GC were controls. Univariate and multivariate analyses were used, with Bonferroni correction.

RESULTS

Patients with EBV-associated GC had tumors of proximal location, lower N stage (P < .0001), and lower T stage (P = .02) and were older than controls (P = .0003). Upon univariate analysis, patients with EBV-associated GC had longer survival times than controls (P < .004); this difference was not significant in a multivariate analysis with Cox proportional hazards. Stratification of EBV-associated GCs by host cellular immune responses showed that patients with LELC and LELC+CLR have significantly longer overall survival time (hazard ratio, 0.09 and 0.42, respectively) and disease-free survival (hazard ratio, 0.05 and 0.46, respectively; P < .02).

CONCLUSIONS

Prognosis of EBV-associated GCs depends on the patient's inflammatory response. The definition of LELC should be expanded to include EBV-associated GCs with CLR because these have a prognosis similar to LELC.

Meta-analysis of the relationship between Epstein-Barr virus infection and clinicopathological features of patients with gastric carcinoma

Epstein-Barr virus (EBV) infection has been causally associated with occurrence of many malignant neoplasms. EBV-encoded small RNAs (EBERs) have been detected from about 10% of gastric carcinoma tissue cells, suggesting that EBV infection is associated with the development of gastric carcinoma. The present study pooled the data from the papers concerning EBV-related gastric cancers and performed a meta-analysis of 22 research papers. Among these papers, a total of 5475 cases with gastric cancer were enrolled, of whom 411 cases were found EBV-positive, with the EBV-positive rate being 7.5%. Among the EBV-positive gastric cancer cases, the detection rate was 11.1% in males and 3.0% in females. Compared with EBV-negative gastric cancer, EBV-positive gastric cancer had less lymph node metastasis. Based on the histological typing, of the EBV-positive gastric cancers, the diffuse type was 8.1%, and intestinal type was 8.0%. The examined specimen types included stored paraffin blocks and fresh surgically removed specimens, their EBV positive rates were 7.9% and 6.5% respectively. In terms of geographical distribution, the detection rate of EBV-positive gastric cancer was 9.4% in America, 6.1% in Asia and 9.1% in Europe. Meta-analysis showed that EBV infection occurred only in gastric cancer tissue cells and was significantly associated with the patients' gender, lymph node metastases, and the location where tumor tissue generated and geographical distribution (P<0.05), but was not significantly associated with the patients' histological types of tumor and the types of specimens (P>0.05). These results suggested that EBV-positive gastric cancer has distinct clinicopathological features.

Cell cycle regulators, APC/beta-catenin, NF-kappaB and Epstein-Barr virus in gastric carcinomas

AIMS

To evaluate the clinicopathological value of cell cycle regulators, the Wnt pathway, the NF-betaB pathway and Epstein-Barr virus (EBV) and to assess their relationships in gastric carcinoma.

METHODS

We investigated cell cycle regulators (p53, p21, Rb), APC, beta-catenin and NF-kappaB using immunohistochemistry and EBV using in situ hybridisation for EBV encoded small RNAs in 117 cases of gastric carcinoma.

RESULTS

p53 overexpression was more frequently observed in advanced gastric carcinoma and lymph node metastasis than in early carcinoma or in the absence of metastasis (p < 0.05). p21 loss was positively correlated with APC loss, but inversely correlated with beta-catenin nuclear accumulation and NF-kappaB positivity (p < 0.05). EBV positive gastric carcinomas were located in the upper third of the stomach, and more were of the diffuse or mixed types than the EBV negative group (p < 0.05). EBV infection was positively correlated with p21 loss and APC loss and inversely correlated with beta-catenin alteration (p < 0.05). In multivariate analysis, patient age, TNM stage and p53 were independent prognostic factors for gastric carcinoma.

CONCLUSIONS

p53 status is a prognostic marker for gastric carcinoma. p21, APC, beta-catenin and NF-kappaB may be functionally interrelated in gastric carcinogenesis. Loss of p21 and APC may be involved in the carcinogenesis of EBV positive gastric carcinomas.

Nuclear factor-kappa B inhibition reduces markedly cell proliferation in Epstein-Barr virus-infected stomach cancer, but affects variably in Epstein-Barr virus-negative stomach cancer

Nuclear factor-kappa B (NF-kappaB) inhibition by NF-kappaB p65-specific siRNA induced a near-cessation of cell proliferation in EBV-positive stomach cancer cell, and notably diminished cell proliferation in EBV- positive Raji lymphoma cell. In EBV-negative stomach cancer cells, NF-kappaB inhibition affected variably cell proliferation. Regardless of cell type, NF-kappaB inhibition suppressed antiapoptotic function of NF-kappaB, and tended to promote the nuclear accumulation of beta-catenin. This inverse relationship between NF-kappaB and beta-catenin was evident in 120 resected gastric carcinomas. Conclusively, NF-kappaB inhibition may be beneficial in the therapy of EBV-positive stomach cancer, but influence variously EBV-negative stomach cancer.

Variations of Epstein-Barr virus nuclear antigen 1 gene in gastric carcinomas and nasopharyngeal carcinomas from Northern China

The Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1), the only viral protein consistently expressed in all EBV-associated tumors, is classified into five distinct subtypes: P-ala, P-thr, V-leu, V-val and V-pro based on the signature changes at amino acid residue 487. By now, whether the EBNA1 subtypes preferentially associate with particular malignancies or represent geographical polymorphism remains controversial. In China, most studies of the EBNA1 variations focused on nasopharyngeal carcinoma (NPC) in endemic area, among which some suggested the V-val subtype is preferentially associated with NPC. To characterize the variations of EBNA1 in NPC non-endemic area in China and to explore the association of EBNA1 variations with EBV-associated gastric carcinoma (EBVaGC) and NPC, the C-terminal sequences of EBNA1 were analyzed for 41 EBVaGC, 41 NPC biopsies and 55 throat washing (TW) samples from healthy donors in Northern China. Three major patterns of the EBNA1 variations, V-val, P-thrV and V-leuV, were observed, and V-val was the most common subtype in all the three groups, followed by P-thrV and V-leuV. The distribution of the EBNA1 subtypes among EBVaGC, NPC and healthy donors was not significantly different (P>0.05). In addition, preferential linkages between EBNA1 subtypes and EBNA3C variants were found to exist. There was no evidence that particular EBNA1 subtypes are preferentially associated with EBVaGC or NPC in Northern China, suggesting that EBNA1 gene variations are geographically restricted rather than tumor-specific polymorphisms.

Prevalence and characteristics of Epstein-Barr virus-associated gastric carcinomas in Tunisia

OBJECTIVE

Epstein-Barr virus (EBV) has been linked to gastric carcinoma (GC) with worldwide geographical variations of prevalence ranging from 1 to 18% of cases. Investigations carried out in north Africa have shown that some EBV-associated types of cancers are common in this area. This study was taken to determine the prevalence of EBV-associated GC in Tunisia.

METHODS

Ninety-six nonselected GC cases (male/female ratio 1.7/1, mean age 60.9 years, range: 20-88 years) were evaluated for the presence of EBV by polymerase chain reaction as well as by in-situ hybridization for EBV-encoded small RNAs (EBERs) and immunohistochemistry for LMP-1 and EBNA-2 expression.

RESULTS

EBV was detected by polymerase chain reaction in 36% of cases, whereas EBERs were detected in the tumor cells in only four cases (4.1%). Immunohistochemistry for LMP-1 and EBNA-2 was negative in all cases. The mean age for patients harboring EBERs-positive GC was 55.7 years (range: 52-59 years). All EBERs-positive GC cases were males of advanced clinical stage (pT3-pT4). According to Lauren's classification, two cases were of diffuse histological type and two cases were of intestinal type. In three cases, the tumors have a proximal location and in the remaining case the tumor arises in the antrum. All EBV strains detected from EBV-associated GC were exclusively of type A and D, prototype F, and XhoI-maintained variant.

CONCLUSION

We conclude that the prevalence of EBV-associated GC in Tunisia is low (4.1%), suggesting that this virus is not an important etiological factor in GC arising in north African populations. The clinicopathological profile of EBV-associated GC in Tunisia did not differ markedly from that found elsewhere.

Differential protein immunoexpression profiles in appendiceal mucinous neoplasms: a special reference to classification and predictive factors

Appendiceal mucinous neoplasms have been the focus of considerable debate in recent years. We histologically classified 70 appendiceal mucinous neoplasms into three categories: 32 mucinous adenoma, 23 mucinous neoplasm of uncertain malignant potential, and 15 mucinous adenocarcinomas. Immunohistochemistry was performed for 24 proteins in different functional categories, specifically, oncogenic proteins (bcl-2, beta-catenin, CEA, C-erbB2, c-kit, Cox-2, Cyclin D1, EGFR, Ki-67, NF-kappaB, VEGF), tumor suppressors (E-cadherin, FHIT, hMLH1, p53, p63, smad4), cell-cycle regulators (p21, p27, p16), and mucin proteins (MUC1, MUC2, MUC5AC, MUC6). Our data showed that 9 out of the 24 proteins were more frequently altered in the mucinous adenocarcinoma group than in the mucinous adenoma group (P<0.05), including beta-catenin (13% in mucinous adenoma vs 60% in mucinous adenocarcinoma), CyclinD1 (44 vs 87%), Ki-67 (high labeling index: 31 vs 67%), NF-kappaB (19 vs 60%), VEGF (16 vs 87%), E-cadherin (0 vs 47%), p53 (6 vs 40%), MUC2 (9 vs 67%), and MUC5AC (3 vs 40%). The distinct immunoexpression profile of mucinous neoplasm of uncertain malignant potential was placed between those of mucinous adenoma and mucinous adenocarcinoma (P<0.05). Moreover, the mucinous adenoma, mucinous neoplasm of uncertain malignant potential, and mucinous adenocarcinoma categories displayed differences in terms of the number of altered markers among the nine proteins (P<0.05; mean 1.4 vs 2.6 vs 5.5, respectively). In mucinous adenocarcinoma, the p53 status was related to disease-free survival and overall survival of patients (P<0.05, both). NF-kappaB status and the number of altered protein markers made statistically marginal impacts on disease-free survival; also beta-catenin loss, on overall survival of patients. In conclusion, protein immunoexpression profiles may facilitate the classification of appendiceal mucinous neoplasms. In our study, the three tumor categories of mucinous adenoma, mucinous neoplasm of uncertain malignant potential, and mucinous adenocarcinoma exhibited distinct immunoexpression profiles. Five and more altered protein markers, p53 overexpression, NF-kappaB positivity, and beta-catenin loss were predictive factors of adverse clinical outcomes in appendiceal mucinous adenocarcinomas.

Expression of DBC1 and SIRT1 is associated with poor prognosis of gastric carcinoma

PURPOSE

SIRT1 (silent mating-type information regulation 2 homologue 1) expression has been reported to predict poor survival in some cancers. We therefore investigated the expression levels of SIRT1 and its negative regulator, DBC1 (deleted in breast cancer 1), in gastric cancer patients.

EXPERIMENTAL DESIGN

We evaluated immunohistochemical expression of DBC1, SIRT1, and p53 using 3-mm tumor cores from 177 gastric cancer patients for tissue microarray.

RESULTS

Positive expressions of DBC1 and SIRT1 were seen in 62% (109 of 177) and in 73% (130 of 177) of patients, respectively. Expression of DBC1 was significantly correlated with tumor stage (P = 0.007), lymph node metastasis (P < 0.001), tumor invasion (P = 0.001), venous invasion (P = 0.001), histologic types (P < 0.001), p53 expression (P < 0.001), and SIRT1 expression (P < 0.001). SIRT1 expression was also significantly correlated with tumor stage (P < 0.001), lymph node metastasis (P < 0.001), tumor invasion (P < 0.001), histologic types (P < 0.001), and p53 expression (P = 0.001). In addition, expression of DBC1 was significantly associated with shorter overall survival and relapse-free survival by univariate analysis (P < 0.001 and P < 0.001, respectively). SIRT1 expression was also significantly associated with shorter overall survival and relapse-free survival by univariate analysis (P = 0.001 and P = 0.001, respectively). Multivariate analysis showed that tumor stage and expression of DBC1 were independent prognostic factors significantly associated with overall survival and relapse-free survival.

CONCLUSION

This study shows that expression of DBC1 and SIRT1 is a significant prognostic indicator for gastric carcinoma patients.

Epigenetic dysregulation of the host cell genome in Epstein-Barr virus-associated neoplasia

Epstein-Barr virus (EBV), a human herpesvirus, is associated with a wide variety of malignant tumors. The expression of the latent viral RNAs is under strict, host-cell dependent transcriptional control. This results in an almost complete transcriptional silencing of the EBV genome in memory B-cells. In tumor cells, germinal center B-cells and lymphoblastoid cells, distinct viral latency promoters are active. Epigenetic mechanisms contribute to this strict control. In EBV-infected cells, epigenetic mechanisms also alter the expression of cellular genes, including tumor suppressor genes. In Nasopharyngeal Carcinoma, the hypermethylation of certain cellular promoters is attributed to the upregulation of DNA methyltransferases by the viral oncoprotein LMP1 (latent membrane protein 1) via JNK/AP1-signaling. The role of other viral latency products in the epigenetic dysregulation of the cellular genome remains to be established. Analysis of epigenetic alterations in EBV-associated neoplasms may result in a better understanding of their pathogenesis and may facilitate the development of new therapies.

Primary bilateral adrenal B-cell lymphoma associated with EBV and JCV infection

Primary lymphoma of the adrenal gland is a rare and highly aggressive disease, with only a few reports in the literature. The pathogenesis is unknown, but detection of Epstein Barr virus (EBV) genome sequences and gene expression in some cases of primary adrenal lymphomas suggested the virus might be a causative agent of the malignancy. While investigating the presence of genome sequences of oncogenic viruses in a large series of adrenal tumors, both EBV and JC polyomavirus (JCV) DNA sequences were detected in a diffuse large primary bilateral B-cell non-Hodgkin lymphoma of the adrenal gland, which was diagnosed only at postmortem examination in a 77 year-old woman with incidentally discovered adrenal masses and primary adrenal insufficiency. The presence of both EBV and JCV genome sequences suggests the relevance of EBV and JCV coinfection in the pathogenesis of this rare form of B-cell lymphoma.

High levels of Epstein-Barr virus DNA in latently infected gastric adenocarcinoma

Gastric adenocarcinoma is the second leading cause of cancer death worldwide. Epstein-Barr virus (EBV) is present in the malignant cells of approximately 10% of cases. It is unclear whether EBV is being missed in some gastric adenocarcinomas due to insensitive test methods or partial EBV genome loss. In this study, we screened 113 gastric adenocarcinomas from low- and high-incidence regions (United States and Central America) for the presence of EBV using a battery quantitative real-time PCR (Q-PCR) assays targeting disparate segments of the EBV genome (BamH1W, EBNA1, LMP1, LMP2, BZLF1, EBER1) and histochemical stains targeting EBV-encoded RNA (EBER), the latent proteins LMP1 and LMP2, and the lytic proteins BMRF1 and BZLF1. EBV DNA was detected by Q-PCR in 48/75 United States cancers (64%) and in 38/38 Central American cancers (100%), which was a significant difference. EBER was localized to malignant epithelial cells in 8/48 (17%) United States and 3/38 (8%) Central American cancers. Viral loads were considerably higher for EBER-positive vs EBER-negative cancers (mean 162 986 vs 62 EBV DNA copies per 100,000 cells). A viral load of 2000 copies per 100,000 cells is recommended as the threshold distinguishing EBER-positive from EBER-negative tumors. One infected cancer selectively failed to amplify the LMP2 gene because of a point mutation, whereas another cancer had an atypical pattern of Q-PCR positivity suggesting deletion of large segments of the EBV genome. Three different viral latency profiles were observed in the cancers based on constant expression of EBER and focal or variable expression of LMP1 or LMP2, without lytic protein expression. We conclude that EBV DNA levels generally reflect EBER status, and a panel of at least two Q-PCR assays is recommended for sensitive identification of infected cancers.

Epstein-Barr virus and gastric carcinoma: virus-host interactions leading to carcinoma

Epstein-Barr virus (EBV)-associated gastric carcinoma (GC) is a distinct subgroup of GC, comprising 10% of all cases of GC. EBV-associated carcinoma is the monoclonal growth of EBV-infected epithelial cells, and it represents a model of virus-host interactions leading to carcinoma. EBV-infected cells express several latent proteins (latency I program of viral latent gene expression) in EBV-associated GC. However, latent membrane protein 2A (LMP2A) up-regulates the cellular survivin gene through the NFkB pathway, conferring resistance to apoptotic stimuli on the neoplastic cells. EBV-associated GC also shows characteristic abnormality, that is, global and non-random CpG island methylation of the promoter region of many cancer-related genes. Since the viral genes are also regulated by promoter methylation in the infected cells, the DNA methylation mechanism specific to EBV-associated GC may be an exaggeration of the cellular mechanism, which is primarily for defense against foreign DNA. Production of several immunomodulator molecules, inducing tumor-infiltrating lymphocyte and macrophages, serves to form the characteristic histologic pattern in EBV-associated GC. The proposed sequence of events within the mucosa is as follows: EBV infection of certain gastric stem cells; expression of viral latent genes; abnormality of signal pathways caused by viral gene products; DNA methylation-mediated repression of tumor suppressor genes; and monoclonal growth of EBV-infected cells through interaction with other etiologic factors. Potentially useful therapeutic approaches to EBV-associated GC are those that utilize the virus-host interactions, such as bortezomib-induced and viral enzyme-targeted radiotherapy.

Metastasis-associated protein S100A4 and p53 predict relapse in curatively resected stage III and IV (M0) gastric cancer

PURPOSE

Pathologic stage is the most important predictive factor of relapse in gastric cancer after curative resection. However, patients with the same stage often have different risks of relapse. Here, we investigated whether the expressions of molecular markers can supplement the current staging system in terms of relapse prediction.

PATIENTS AND METHODS

One hundred and nine stage III or IV (M0) patients who had received curative gastrectomy followed by adjuvant 5-fluorouracil and cisplatin chemotherapy were included in this study. The expressions of molecular markers including p53, p27, COX-2, HER-2, EGFR, maspin, S100A4, E-cadherin, Sp1, and p97 were analyzed by immunohistochemistry in cancer and paired normal tissues.

RESULTS

The overall relapse rate was 58.7%, and pathologic stage was a significant predictive factor of relapse (42% in stage IIIA, 48% in IIIB, 76% in IV, p = 0.005). Of the 10 markers examined, p53 and S100A4 were expressed only in tumor tissues, and S100A4 expression was significantly associated with a higher relapse rate (85% vs. 53%, p = 0.008). In multivariate analysis including tumor stage, S100A4 and p53 expression were independent predictive factors of relapse (relative risk, 6.98; 95% confidence interval [CI], 1.608-30.342, 3.49; 95% CI, 1.328-9.186, respectively). On comparing patients who expressed S100A4 or p53 with those who expressed neither, relapse rates were 58% vs. 25% in stage III (p = 0.011) and 95% vs. 59% in stage IV (M0) (p = 0.003).

CONCLUSION

In addition to staging system, the expressions of S100A4 and p53 were significant predictive factors of relapse in gastric cancer after curative resection and adjuvant chemotherapy.

H pylori (CagA) and Epstein-Barr virus infection in gastric carcinomas: Correlation with p53 mutation and c-Myc, Bcl-2 and Bax expression

AIM: To investigate the interrelationship between H pylori and Epstein-Barr virus (EBV) infection in the gastric carcinogenesis having in focus the p53 mutation and the c-Myc, Bcl-2 and Bax expression.

METHODS: seventy-one gastric carcinoma tissues were assessed by polymerase chain reaction (PCR) for H pylori and in situ hybridization for EBV. c-Myc, Bcl-2 and Bax expression were detected by immunohistochemistry and single-stranded conformational polymorphism (SSCP) for p53 mutation.

RESULTS: The positivity rates for H pylori and EBV were 94.4% and 8.45%, respectively. The majority of the cases displayed only the H pylori presence. All EBV positive cases were also H pylori positive. None infectious agent was observed in 5.55% of the cases. The intestinal type tumor was more frequent in the co-infected and non-infected groups. The female predominated in the non-infected group showing statistical significance (70.4% vs 29.6%, P = 0.039). The Bcl-2 was only detected in the group exclusively infected by H pylori. However, c-Myc and Bax were detected in the three groups but with a low frequency in the co-infected group. Mutation of p53 was present in all groups, with the highest frequencies in the H pylori positive groups.

CONCLUSION: The frequency of H pylori infection in gastric carcinomas was high. The presented data indicated that gastric carcinogenesis has different pathways depending of the presence of the two investigated infectious agents, suggesting a possible involvement of H pylori with apoptotic process. The low expression of c-Myc and Bax in the EBV-positive groups suggests that EBV may inhibit the expression of these proteins. Nevertheless, p53 mutation shows to be a relevant alteration, independent of both infectious agents.

Epstein-Barr virus associated gastric carcinoma: epidemiological and clinicopathological features

In this paper, the roles of Epstein-Barr virus (EBV) in gastric carcinogenesis are discussed, reviewing mainly epidemiological and clinicopathological studies. About 10% of gastric carcinomas harbor clonal EBV. LMP1, an important EBV oncoprotein, is only rarely expressed in EBV-associated gastric carcinoma (EBV-GC) while EBV-encoded small RNA is expressed in almost every EBV-GC cell, suggesting its importance for developing and maintaining this carcinoma. In addition, the hypermethylation-driven suppressor gene downregulation, frequently observed in EBV-GC, appears to give a selective advantage for carcinoma cells. EBV reactivation is suspected to precede EBV-GC development since antibodies against EBV-related antigens, including EBV capsid antigen (VCA), are elevated in prediagnostic sera. Interestingly, the average anti-VCA immunoglobulin G antibody titer in EBV-GC patients was significantly higher among men than among women, whereas EBV-negative GC cases did not show such a sex difference. A higher frequency of human leucocyte antigen-DR11 in EBV-GCs suggests that major histocompatibility complex-restricted EBV nuclear antigen 1 epitope recognition may enhance EBV reactivation. EBV infection of gastric cells by lymphocytes with reactivated EBV is suspected to be the first step of EBV-GC development. Male predominance of EBV-GC suggests the involvement of lifestyles and occupational factors common among men. The predominance of EBV with XhoI+ and BamHI type i polymorphisms in EBV-GC in Latin America suggests a possibility of some EBV oncogene expressions being affected by EBV polymorphism. The lack of such predominance in Asian countries, however, indicates an interaction between EBV polymorphism and the host response. In conclusion, further studies are necessary to examine the interaction between EBV infection, its polymorphisms, environmental factors, and genetic backgrounds.

Immunohistochemical biomarkers of value in distinguishing primary ovarian carcinoma from gastric carcinoma: a systematic review with statistical meta-analysis

AIMS

To compare the relative risk of antigen expression being detected immunohistochemically in ovarian and gastric carcinoma aggregated from studies performed for diagnostic purposes, with the relative risks of their expression in all patients in the English literature.

METHODS AND RESULTS

Both types of series indicated that cytokeratin (CK) 7 expression was greater and that of CK20 and carcinoembryonic antigen less in ovarian than in gastric carcinoma (P < 0.05). Synthesis of all data available for MUC-2 suggested it was more commonly expressed in ovarian carcinoma, whereas the relative risk in papers that directly compared its expression suggested that it was more common in the gastric carcinoma (P = 0.2, NS). Aggregating all possible data suggested villin was more likely to be expressed in ovarian cancers, whereas studies in which its expression was compared directly in both tumours suggested the opposite. Although statistically significant, patient numbers were small.

CONCLUSION

Provided sufficient numbers of cases are studied, analysis of studies comparing antigen expression for diagnostic purposes in tumours from two body sites is likely to be supported in the wider literature. The design of such comparative studies is informed by aggregating data from single tumour studies.

Epstein-Barr virus serology and gastric cancer incidence and survival

Among 185 cases of gastric cancer and 200 controls in Linxian, China, Epstein–Barr virus (EBV) seropositivity was not associated with increased risk of gastric cancer. High EBV nuclear antigen titres were associated with longer survival in cardia cancer cases, possibly due to chance.

Detection of polyomaviruses and herpesviruses in human adrenal tumors

The presence of polyomaviruses and herpesviruses in adrenal tumors and their role in adrenal tumorigenesis has never been investigated, even though the adrenal gland seems to be a preferential site of infection by these viruses and adrenal steroid hormones have been shown to activate their replication. We examined in a large series of normal adrenal gland tissues (n=20) and adrenal tumors (n=107) the presence of herpesviruses and polyomaviruses sequences and gene expression, which were detected in a high proportion of both normal and neoplastic adrenal samples (overall, viruses were found in 15% normal adrenals, 27.8% benign adrenal tumors and 35.3% malignant tumors). The polyomaviruses SV40 and BK virus were more frequently found in malignant adrenal tumors, whereas herpesviruses, especially Epstein-Barr virus and human cytomegalovirus, were more frequently detected in functioning benign adrenocortical tumors, often as coinfection. Moreover, tumors from patients with severe hypercortisolism frequently showed herpesvirus coinfections at high viral genome copy number. Our study suggests that the adrenal gland could be a reservoir of infection for these viruses and that hormone overproduction by the adrenal gland could represent a trigger for virus reactivation. On the other hand, these viruses could also contribute to adrenal cell proliferation and tumorigenesis.

Differential expression of apoptosis related proteins and nitric oxide synthases in Epstein Barr associated gastric carcinomas

AIM: To determine the incidence of Epstein Barr virus associated gastric carcinoma (GC) in Brazil and compare the expressions of apoptosis related proteins and nitric oxide synthases between EBV positive and negative gastric carcinoma.

METHODS: In situ hybridization of EBV-encoded small RNA-1 (EBER-1) and PCR was performed to identify the presence of EBV in GCs. Immunohistochemistry was used to identify expressions of bcl-2, bcl-xl, bak, bax, p53, NOS-1, NOS-2, and NOS-3 proteins in 25 EBV positive GCs and in 103 EBV negative GCS.

RESULTS: 12% of the cases of GC (25/208) showed EBER-1 and EBNA-1 expression. The cases were preferentially of diffuse type with intense lymphoid infiltrate in the stroma. EBV associated GCs showed higher expression of bcl-2 protein and lower expression of bak protein than in EBV negative GCs. Indeed, expressions of NOS-1 and NOS-3 were frequently observed in EBV associated GCs.

CONCLUSION: Our data suggest that EBV infection may protect tumor cells from apoptosis, giving them the capacity for permanent cell cycling and proliferation. In addition, EBV positive GCs show high expression of constitutive NOS that could influence tumor progression and aggressiveness.

No association of primary adenocarcinomas of the small bowel with Epstein-Barr virus infection

Epstein-Barr Virus (EBV) infection is considered to play an etiologic role in human malignancies, including a subset of gastric and cardiac cancers. Adenocarcinomas of the small bowel comprise a very rare entity, with little knowledge about molecular properties and etiological aspects. We have investigated the prevalence of EBER expression (EBV-encoded small RNAs) in a series of small bowel adenocarcinomas (n=56) utilizing RNA in situ hybridization (EBER-RISH). The patients had undergone primary surgical resection at either the Technical University of Munich or at the University of Graz. A surgical series of 82 primary resected gastric (n=36) or cardiac (n=46) adenocarcinomas (TU Munich) was used as control group. None of the 56 small bowel carcinomas exhibited EBER expression whereas in the control group the rate of EBER expression accounted for 4.4% in the group of cardia carcinomas and 8.6% in the group of gastric cancers. These results indicate that EBV infection plays no etiologic role in primary small bowel adenocarcinomas.

Genetic, epigenetic, and clinicopathologic features of gastric carcinomas with the CpG island methylator phenotype and an association with Epstein-Barr virus

BACKGROUND

The CpG island methylator phenotype (CIMP), which is characterized by simultaneous methylation of the CpG islands of multiple genes, has been recognized as one of the important mechanisms in gastrointestinal carcinogenesis.

METHODS

Methylation of the 5 methylated-in-tumors (MINT) loci and 12 tumor-related genes in 78 primary gastric carcinomas was examined using combined bisulfite-restriction analysis. Epstein-Barr virus (EBV)-associated gastric tumors were detected using real-time polymerase chain reaction analysis followed by an evaluation of the correlations between CIMP status, EBV-association, and genetic alteration of p53 and K-ras. The authors compared the clinicopathologic features of gastric carcinomas that had high CIMP methylation (CIMP-H) with tumors that had low CIMP methylation (CIMP-L) or negative CIMP methylation (CIMP-N).

RESULTS

The methylation profiles of 12 genes showed nonrandom methylation, supporting the presence of CIMP in gastric carcinoma. No p53 mutations were detected among CIMP-H tumors, and no EBV association was detected in tumors that showed mutation of p53 and K-ras. In a multiple logistic regression model with CIMP-H as the dependent variable, proximal location (P = .011), diffuse type (P = .019), and less advanced pathologic TNM status (P = .043) contributed significantly to CIMP-H. Patients who had CIMP-N gastric tumors had a significantly worse survival than patients who had CIMP-H tumors (P = .004) or CIMP-L tumors (P = .012). EBV-associated tumors were associated strongly with CIMP-H, hypermethylation of tumor-related genes, and no p53 or K-ras mutation.

CONCLUSIONS

CIMP status appeared to be associated with distinct genetic, epigenetic, and clinicopathologic features in gastric carcinomas. The finding that gastric carcinomas arose through different molecular pathways may affect not only tumor characteristics but also patient prognosis.

Tissue array methods for high-throughput clinicopathologic research

Recent research in molecular biology has identified a significant number of novel markers, which may have diagnostic, prognostic and therapeutic significance. High-throughput tissue array method facilitates the validation of novel markers by enabling the simultaneous analysis of hundreds or thousands of tissue specimens. Tissue array slides can be analyzed using techniques such as immunohistochemistry and in situ hybridization. In this review, we give a brief overview of tissue array method and its application to high throughput clinicopathologic research.

Morphological Evidence of an Activated Cytotoxic T-Cell Infiltrate in EBV-Positive Gastric Carcinoma Preventing Lymph Node Metastases

Recently, we showed that Epstein-Barr virus (EBV)-positive gastric carcinoma (GC) forms a distinct clinicopathologic entity with a better prognosis due to lower incidence of lymph node metastases (LN+). Here we investigated whether in EBV-positive GC more pronounced activation of cellular immune responses is associated with absence of (micro)metastases. Twenty EBV-positive primary tumors (PT) (9 LN+) were matched with 28 EBV-negative GC (11 LN+) for T- and N-stage, gender, and age. The PT (n = 28) and its LNs were analyzed by EBER RNA in situ hybridization and by immunohistochemistry for MHC class I and II expression, for CD3, CD8, CD4, CD20, CD56, CD83, and Granzyme B (GzB) expression. In LN metastases of EBV-positive GC, the EBV genome is maintained, excluding tumor escape by virus deletion. All GC express MHC class I independently of EBV status. In comparison with EBV-negative GC, EBV-positive GC have higher expression of MHC class II on the tumor cells (P = 0.029) and a more extensive infiltrate (P < 0.0001) of activated GzB+ CD8+ T cells (P = 0.028), which is most abundant in those EBV-positive tumors that do not metastasize (P < 0.0001). In addition, in EBV-positive GC without metastases, the infiltrate contains higher numbers of mature dendritic cells (DC) (P = 0.018). At present, the antigenic target has to be determined. These data support the notion that local triggering of cellular immune responses in EBV-positive GC prevents lymph node metastasis formation.

Epstein-Barr virus in human malignancy: a special reference to Epstein-Barr virus associated gastric carcinoma

Epstein-Bar virus (EBV), a human herpesvirus, establishes a life-long persistent infection in 90 approximately 95% of human adult population worldwide. EBV is the etiologic agent of infectious mononucleosis, and EBV is associated with a variety of human malignancy including lymphoma and gastric carcinoma. Recently, EBV has been classified as group 1 carcinogen by the WHO International Agency for Research on Cancer. Evidence is presented which suggests that failures of the EBV-specific immunity may play a role in the pathogenesis of EBV-associated malignancy. At present, the precise mechanisms by which EBV transforms B lymphocytes have been disclosed. Encouragingly, they have had enough success so far to keep them enthusiastic about novel therapeutic trial in the field of EBV-associated lymphoma. However, information on EBV-associated gastric carcinoma is still at dawn. This article reviews EBV biology, immunological response of EBV infection, unique oncogenic property of EBV, peculiarity of EBV-associated gastric carcinoma, and lastly, EBV-targeted therapy and vaccination.

Gene deregulation in gastric cancer

Despite its decreasing frequency in the Western world during recent decades, gastric cancer is still one of the leading causes of cancer-related deaths worldwide. Due to the oligosymptomatic course of early gastric cancer, most cases are diagnosed in the advanced stages of the disease. The curative potential of current standard treatment continues to be unsatisfactory, despite multimodal approaches involving surgery, chemotherapy and radiotherapy. Novel therapeutics including small molecules and monoclonal antibodies are being developed and have been partially introduced into clinical use in connection with neoplastic diseases such as chronic myeloid leukemia, non-Hodgkin's lymphoma and colorectal cancer. Thorough understanding of the changes in gene expression occurring during gastric carcinogenesis may help to develop targeted therapies and improve the treatment of this disease. Novel molecular biology techniques have generated a wealth of data on up- and down-regulation, activation and inhibition of specific pathways in gastric cancer. Here, we provide an overview of the different aspects of aberrant gene expression patterns in gastric cancer.

MUC1, MUC2, MUC4, and MUC5AC expression in salivary gland mucoepidermoid carcinoma: diagnostic and prognostic implications

We determined whether immunostaining for mucins could provide a better characterization of salivary gland mucoepidermoid carcinoma (MEC). We investigated 63 MECs by immunohistochemistry for MUC1, MUC2, MUC4, and MUC5AC. Mucin expressing cell types and labeling patterns were recorded. The results were compared with microscopic grade, tumor-associated lymphoid infiltrate, mucin expression in surrounding salivary glands, clinical features, and outcome. MUC1 and MUC4 labeled the apical membrane of glandular tumor cells and the entire membrane of intermediate, clear, and epidermoid tumor cells. MUC2 and MUC5AC were expressed in the cytoplasm of glandular, mucous, and intermediate tumor cells. In contrast to MUC1, MUC4 expression decreased with tumor grade (P < 0.01). Unlike MUC2, MUC5AC was expressed in more than 50% of high-grade tumors, including 2 cases that were not stained with Alcian blue. MUC1 and MUC5AC were associated with tumor-associated lymphoid infiltrates (P < 0.05), but not with tumor-associated lymphoid follicles. The proportions of tumors expressing mucins were 71% for MUC1, 21% for MUC2, 79% for MUC4, and 68% for MUC5AC. MUC1 and MUC5AC were more frequently expressed in tumors than in surrounding glands (P < 0.0001). MUC1 expression correlated with shorter progression-free survival (P < 0.05). In conclusion, mucin expression in MEC differs from that in salivary glands. Intermediate cells express MUC1 and MUC4 all along their cell surface and MUC2 and MUC5AC in their cytoplasm. Staining for MUC5AC in high-grade tumors can be helpful for distinguishing high-grade MEC from squamous cell carcinoma. While MUC4 is related to tumor differentiation, MUC1 expression indicates a worse prognosis.

Relationship between abnormality of FHIT gene and EBV infection in gastric cancer

AIM: To examine the aberrant expression of fragile histidine triad (FHIT) gene and protein in gastric cancer, and to evaluate the role of FHIT gene and the relationship between FHIT gene and EBV infection in gastric carcinogenesis.

METHODS: FHIT transcripts were detected by nested RT-PCR in 30 cases of gastric cancer and their products were sequenced. FHIT protein was detected by Western blot. EBV infection was detected by PCR method in 50 cases of gastric cancer.

RESULTS: The wild type transcripts were detected in all 30 matched normal tissues of gastric cancer. Aberrant transcripts were found in 11/30 (36.7%) gastric cancerous tissues. Sequencing analysis of the aberrant fragments found an RT-PCR product missing exons 5-7 in one case of gastric cancer, and another product missing exons 4-7. Four of ten (40.0%) cases of primary gastric cancer showed absent or decreased expression of FHIT protein as compared with their matched normal tissues. EBV was detected in 5/50 (10%) gastric cancers, among which 4/5 (80%) had aberrant transcripts of FHIT gene.

CONCLUSION: Loss of FHIT gene or FHIT protein plays an important role in carcinogenesis, development and progression of gastric cancer. EBV infection might influence carcinogenesis of gastric cancer by inducing the abnormality of FHIT gene.

Clinicopathologic and protein expression differences between cardia carcinoma and noncardia carcinoma of the stomach

BACKGROUND

Although the incidence of adenocarcinoma of the stomach has decreased over the past several decades, gastric cardia carcinoma has increased over the same period.

METHODS

The clinicopathologic characteristics and immunohistochemical staining results of 21 proteins were investigated in 165 patients with cardia carcinoma, including 74 patients with true cardia carcinoma and 91 patients with subcardia carcinoma, and the results were compared with the results from 564 patients with noncardia carcinoma.

RESULTS

In the clinicopathologic analysis, patients who had cardia carcinoma tended to have tumors with poorly differentiated histology according to the World Health Organization classification system (P = 0.012), diffuse type according to the Lauren classification system (P = 0.049), and advanced pathologic TNM stage (P < 0.001). On immunohistochemical staining, loss of the p16 (P = 0.038) and smad4 (P < 0.001) tumor suppressor genes was more frequent in cardia carcinoma than in noncardia carcinoma. Carcinoembryonic antigen and CD44 overexpression were more frequent in patients with cardia carcinoma (P < 0.05). Conversely, patients who had cardia carcinoma exhibited less frequent expression of MUC1 (P = 0.008) and MUC5AC (P = 0.006) compared with patients who had noncardia carcinoma. Epstein-Barr virus infection was more common in patients with cardia carcinoma (P < 0.001). In the survival analysis, the patients with cardia carcinoma had a poorer prognosis. In the multivariate analysis, tumor location in the cardia was confirmed as an independent, poor prognostic factor in patients with gastric carcinoma.

CONCLUSION

Cardia carcinoma and noncardia carcinoma differed in their clinicopathologic characteristics and in their alterations of gene expression, as evaluated by immunohistochemistry. The current results support the hypothesis that cardia carcinoma forms a specific category of gastric carcinoma that is distinct from noncardia carcinoma.

Epstein-Barr virus and aberrant expression of mdm2 and p53 in pathogenesis and development of gastric carcinoma

AIM: To investigate the role of p53 and mdm2 gene abnormality in oncogenesis and development of Epstein-Barr virus (EBV) -associated gastric carcinoma (EBVaGC) and to explore the relationship between EBV infection and p53 and mdm2 protein expression.

METHODS: p53 gene mutation in exon 5-8 was detected by polymerase chain reaction and single strand conformation polymorphism analysis (PCR-SSCP), and DNA sequencing. p53 and mdm2 protein expression was tested by immunohistochemistry in EBVaGCs (n = 13), EBVnGCs (EBV negative gastric carcinomas, n = 45) with matched clinicopathological parameters and corresponding adjacent tissues of gastric carcinoma (n = 58).

RESULTS: The positive rates of p53 and mdm2 protein in gastric carcinomas were significantly higher than those in corresponding adjacent normal tissues (86.2%, 29.3% vs 0%, 0% respectively; P < 0.01). There were no significant difference between the positive rates of p53 and mdm2 protein in EBVnGCs and EBVaGCs. The overexpression rate of p53 protein was 15.4% (2/13) in EBVaGCs. This was in marked contrast to the rate of 57.8% (26/45) in EBVnGCs (χ² = 7.2593, P = 0.0 085 < 0.01). There was significant positive correlation between mdm2 expression and p53 overexpression (χ² = 11.1 839, P = 0.0 008 < 0.01, r = 0.4 391). p53 gene mutation was found in only 2 cases of EBVnGCs and both occurred at exon 5. No p53 gene mutation was detected in 13 cases of EBVaGCs and 58 corresponding adjacent tissues.

CONCLUSION: Abnormal accumulation of p53 protein might not result from p53 gene mutation. mdm2 protein may play an important role in the pathogenesis of gastric carcinoma through suppressing the function of wild type p53 protein. The infection of EBV relates to the abnomal expression of p53 protein, but not to the abnomal expression of mdm2 protein and p53 gene mutation in gastric carcinoma

Epstein-Barr virus: 40 years on

Epstein-Barr virus (EBV) was discovered 40 years ago from examining electron micrographs of cells cultured from Burkitt's lymphoma, a childhood tumour that is common in sub-Saharan Africa, where its unusual geographical distribution - which matches that of holoendemic malaria -indicated a viral aetiology. However, far from showing a restricted distribution, EBV - a gamma-herpesvirus - was found to be widespread in all human populations and to persist in the vast majority of individuals as a lifelong, asymptomatic infection of the B-lymphocyte pool. Despite such ubiquity, the link between EBV and 'endemic' Burkitt's lymphoma proved consistent and became the first of an unexpectedly wide range of associations discovered between this virus and tumours.