EBV-associated gastric carcinoma in high- and low-incidence areas for nasopharyngeal carcinoma

Background:

Approximately 10% of gastric carcinomas are associated with Epstein–Barr virus (EBV). The Inuit in Greenland have a high incidence of EBV-associated nasopharyngeal carcinoma.

Methods:

We conducted a population-based case–control study comparing gastric carcinomas in Greenland and in Denmark.

Results:

The prevalence rate of EBV-associated gastric carcinomas was 8.5% in both populations.

Conclusion:

The findings of this study argue against a general susceptibility to EBV-associated carcinomas among the Inuit.     

The protective role of polymorphism MKK4-1304 T>G in nasopharyngeal carcinoma is modulated by Epstein-Barr virus' infection status

MKK4 is a candidate tumor suppressor, which acts as a critical mediator of Epstein-Barr Virus (EBV)-induced c-Jun N-terminal kinase (JNK) activation. Functional polymorphism MKK4 -1304T>G has been showed to be protective in colorectal cancer or lung cancer. We hypothesized that genetic variants in the MKK4 promoter were associated with the risk of nasopharyngeal carcinoma (NPC). Two common polymorphisms in MKK4, -1304T>G and -1044A>T were genotyped in two independent case-control panels of Eastern and Southern Chinese populations, totally containing 1237 NPC and 1328 controls. We found that compared to the most common -1304TT genotype, carriers of variant genotypes (-1304TG+GG) were associated with a significantly reduced risk for NPC in total subjects (adjusted OR = 0.78; 95%CI = 0.67-0.94). Further stratification analysis showed that the protective effect was more pronounced in EBV negative status (adjusted OR = 0.51; 95%CI = 0.41-0.68) but restrained in those with EBV infection (adjusted OR = 1.05; 95%CI = 0.88-1.26), and that the -1304GG variant genotypes interacted with EBV negative status on reducing cancer risk (p = 0.011). However, no significant association was observed between the -1044A>T polymorphism and risk of NPC. Our data suggest that the protective role of genetic variant MKK4 -1304T>G is restrained in NPC with EBV infection. These findings implicate the role of EBV and MKK4 -1304 T>G interaction as a causative factor for the NPC.     

Role of the MDM2 SNP309 polymorphism in the initiation and early age of onset of nasopharyngeal carcinoma

Recent studies refer that amplification/overexpression of the principal negative regulator of p53 (Mdm2) is frequently found in several malignancies. Several studies have associated a polymorphism (SNP309 T/G) in the promoter region of MDM2 with higher levels of this protein, which will favor p53‐pathway abolishment, cell‐cycle escape, and development of cancer. We aimed to study if MDM2 SNP309 T/G polymorphism contributes to the development of nasopharyngeal carcinoma (NPC). We have developed a case–control study with 124 patients with NPC and 509 healthy individuals from the north of Portugal to determine the genetic distribution of the MDM2 SNP309 polymorphism in DNA extracted from peripheral blood samples. Statistical analysis was performed to compare categorical variables adjusted for age and gender by multivariate logistic regression. Genotype‐specific distributions according to age of onset were tested by Kaplan–Meier method and analyzed by Cox‐regression proportional hazard model adjusted for gender. This study revealed that MDM2 SNP309 GG homozygous represent an increased risk adjusted for age and gender to develop NPC (OR = 2.15), with particular effect in undifferentiated types (OR = 2.46) and early clinical stages (OR = 3.32). We also found that median age of onset of NPC was significantly different (55.2 vs. 61.6) with increased effect in undifferentiated types (55.2 vs. 61.9) and early clinical stages (55.3 vs. 65.3). Our study suggests that MDM2 SNP309 can be considered a risk marker for the development of NPC mainly in early ages probably as an initiation marker for potential cancer development. © 2010 Wiley‐Liss, Inc.     

Correlates of anti-EBV EBNA1 IgA positivity among unaffected relatives from nasopharyngeal carcinoma multiplex families

Background:

To determine whether non-viral nasopharyngeal carcinoma (NPC) risk factors might be associated with (and mediated through) Epstein–Barr virus (EBV) serological responses linked to NPC risk, we evaluated predictors of risk of anti-EBNA1 IgA seropositivity and other markers among unaffected relatives from a large NPC family study in Taiwan.

Methods:

Multivariate logistic regression conditioned on family was used to examine the associations between sociodemographic, dietary, lifestyle, and occupational variables and risk of anti-EBV EBNA1 IgA positivity, anti-VCA IgA, and anti-DNase positivity.

Results:

Among 2393 unaffected relatives from 319 multiplex families, 1180 (49.3%) were anti-EBV EBNA1 IgA seropositive. None of the associations with anti-EBNA1 IgA were statistically significant, except for being 31–50 years of age (vs <30, adjusted ORs 0.51–0.57). For one or more EBV serological markers, there were suggestive associations for older age, GuangDong firm salted fish, betel use, current alcohol use, and male gender.

Conclusion:

Overall, we found little evidence to suggest that non-viral NPC risk factors significantly alter EBV serological patterns, suggesting that non-viral NPC risk factors act through pathways independent of EBV serological responses.     

Cancer patterns in nasopharyngeal carcinoma multiplex families in Taiwan

Genetic and environmental factors have been implicated in the etiology of nasopharyngeal carcinoma (NPC), a tumor known to be closely associated with Epstein‐Barr virus (EBV) infection. Studies have reported familial aggregation of NPC and have suggested the possible aggregation of NPC and other cancers. We evaluated familial aggregation of cancer in 358 high‐risk families with two or more NPC cases enrolled in a NPC genetics study in Taiwan. Participants were linked to the Taiwan National Cancer Registry to identify incident cancers diagnosed after study enrollment (started in 1996) and before December 31, 2005, or death. In total, 2,870 individuals from the NPC Multiplex Family Study contributed 15,151 person‐years over an average of 5.3 years of follow‐up. One hundred ten incident cancers were identified. Multiple‐primary standardized incidence ratios (MP‐SIRs) were computed to evaluate overall cancer risk associated with infectious agents and with other tumors. The overall MP‐SIR was 1.3 (95% CI: 1.1–1.6), which was largely explained by an excess in NPC (MP‐SIR = 15; 95% CI: 10–23). Exclusion of incident NPC diagnoses led to an overall MP‐SIR of 1.0 (95% CI: 0.83–1.3). Similarly, the observed excess risk of cancers associated with infectious agents (MP‐SIR = 2.0; 95% CI: 1.5–2.6) was driven by the excess in NPC; exclusion of NPC cases led to a reduced MP‐SIR that did not differ from 1.0. Analysis of the largest NPC multiplex family study to date confirms the presence of coaggregation of NPC within families in Taiwan but does not provide evidence for a broader familial syndrome involving NPC and other tumors. © 2008 Wiley‐Liss, Inc.     

Epstein-Barr virus seroreactivity among unaffected individuals within high-risk nasopharyngeal carcinoma families in Taiwan

Most adults have been infected with EBV. Many studies have indicated that antibodies against specific EBV antigens, particularly IgA antibodies, can be predictive or prognostic of EBV-associated malignancies, such as NPC. We hypothesized that healthy individuals from families with a history of multiple members affected with NPC (who therefore might be genetically susceptible to NPC themselves) might have an EBV antibody profile that is distinct from that seen in healthy individuals from the community at large. To explore this possibility and examine determinants of anti-EBV antibody levels in healthy, high-risk individuals, we evaluated data from 2 parallel studies of NPC in Taiwan, which included 1,229 healthy members of families in which 2 or more individuals were affected with NPC and 320 controls from the community at large. Blood collected from participants was tested for IgA antibodies against EBV VCA and EBNA-1 and for neutralizing antibodies against EBV DNase using standard assays. We observed evidence of familial aggregation of EBV seroreactivity among individuals from high-risk, multiplex NPC families. Anti-VCA IgA and anti-EBNA-1 IgA antibody seroprevalence in unaffected family members of NPC cases was 5-6 times higher than in members of the community (p < 0.01). This elevated seroprevalence among unaffected individuals from high-risk families was observed regardless of the relationship of the unaffected individual to the closest affected relative (siblings, parents, children or spouses). No sociodemographic or environmental factors examined were found to strongly and consistently correlate with elevated seroprevalence, but patterns emerged of increasing seroprevalence among older individuals and among females. Unaffected individuals from high-risk NPC families have elevated anti-EBV IgA antibody titers. The etiologic and clinical implications of this finding remain to be established.     

鼻咽癌组织中DAPK基因启动子甲基化的研究

目的:分析鼻咽癌组织中DAPK基因启动子的甲基化状态,探讨DAPK基因启动子甲基化与鼻咽癌的关系。方法:应用甲基化特异性PCR技术检测48例鼻咽癌组织、26例慢性鼻咽黏膜炎症组织的DAPK基因启动子甲基化状态,比较鼻咽癌和慢性鼻咽黏膜炎症组织的DAPK基因启动子甲基化率。结果:鼻咽癌组织的DAPK基因启动子甲基化率为75%,而慢性鼻咽黏膜炎症组织中未检测到DAPK基因启动子甲基化。结论:鼻咽癌组织中DAPK基因启动子存在高甲基化水平,检测DAPK基因启动子甲基化或许能为鼻咽癌的诊断提供依据。     

Quantification of Epstein–Barr virus DNA load in nasopharyngeal brushing samples in the diagnosis of nasopharyngeal carcinoma in southern China

Nasopharyngeal carcinoma (NPC) is highly incident in southern China, where 40% of world's new cases arise each year. Detection of Epstein–Barr virus (EBV) DNA load in nasopharyngeal (NP) brush/swab samples has gradually been established as a method for diagnosis of NPC. However, its applicable value in NPC diagnosis has never been investigated in southern China. It is important to explore whether such a test could be applicable to our local population. A total of 245 consecutive participants undergoing NP brushing examination were recruited to obtain the NP brushing samples in this study. Quantitative PCR assays were used to obtain the EBV DNA load. Mann–Whitney, ANOVA and receiver operating characteristic tests were used to analyze its diagnostic value. NP brushing samples from NPC patients showed extremely high levels of EBV DNA load (mean = 46360 copy/ng DNA) compared to its expression from non‐NPC control (mean = 28 copy/ng DNA) and high‐risk control (mean = 50 copy/ng DNA) groups. It produced 96% sensitivity and 97% specificity, at the COV = 225 copy/ng DNA. Furthermore, EBV DNA load could reflect disease progress. Our data showed a better performance of EBV DNA load in NP brushing samples compared with an initial biopsy, immunoglobulin A (IgA) antibody titers to viral capsid antigen in serum and EBV DNA load in plasma. Detection of EBV DNA load in NP brushing samples could be an effective supplement for NPC diagnosis. Being minimally invasive and low cost, NP brush sampling combined with EBV DNA detection demonstrates great potential for screening high‐risk populations for NPC.     

亚砷酸诱导人鼻咽癌细胞中p16基因表达的研究

目的 研究亚砷酸( As2O3)诱导鼻咽癌(nasopharyngeal carcinoma,NPC)CNE- 2Z细胞株中抑癌基因p16的表达.方法 体外培养的CNE-2Z细胞分别加入不同浓度的亚砷酸,并作用于不同时间.用终浓度为2μmol/L、1 μmol/L、0.5μmol/L的As2O3加入鼻咽癌CNE-2...     

Inhibiting tumorigenic potential by restoration of p16 in nasopharyngeal carcinoma

The p16 gene, encodes a key checkpoint protein p16 in the cell cycle, has been reported inactivation in a wide variety of human cancers. We have previously demonstrated high frequency of p16 alterations in primary nasopharyngeal carcinoma (NPC), xenografts and cell lines. The finding implied that inactivation of the p16 gene may play an important role in the NPC development. To investigate the tumour suppressor function of p16 in NPC, we transfected p16-deficient NPC cell line, NPC/HK-1, with a wild-type p16 expression construct, and evaluated growth and tumorigenic properties of the clones stably expressing exogenous p16. Expression of the exogenous wild-type p16 significantly inhibited cell growth by more than 70% when compared to that of the parental and empty vector-transfected cells. This growth inhibition was attributable to a significant proportion of p16-expressing cells arrested at G1 phase in the cell cycle as revealed by flow cytometric analysis. By anchorage-independent colony forming assay, we found that the ability to form colonies in soft agar was highly reduced in cells expressing p16. NPC/HK1 cells expressing functional p16 also showed suppressed tumorigenicity in athymic nude mice. Taken together, our results provide strong evidence for a tumour suppressor role of p16 in NPC.     

Tumor suppressor genes on frequently deleted chromosome 3p in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is among the most common malignancies in southern China.Deletion of genomic DNA,which occurs during the complex pathogenesis process for NPC,represents a pivotal mechanism in the inactivation of tumor suppressor genes (TSGs).In many circumstances,loss of TSGs can be detected as diagnostic and prognostic markers in cancer.The short arm of chromosome 3 (3p) is a frequently deleted chromosomal region in NPC,with 3p21.1-21.2 and 3p25.2-26.1 being the most frequently deleted minimal regions.In recent years,our research group and others have focused on the identification and characterization of novel target TSGs at 3p,such as RASSF1A,BLU,RBMS3,and CHL1,in the development and progression of NPC.In this review,we summarize recent findings of TSGs at 3p and discuss some of these genes in detail.A better understanding of TSGs at 3p will significantly improve our understanding of NPC pathogenesis,diagnosis,and treatment.     

Viral hit and run-oncogenesis: Genetic and epigenetic scenarios

It is well documented that viral genomes either inserted into the cellular DNA or coreplicating with it in episomal form can be lost from neoplastic cells. Therefore, “hit and run”-mechanisms have been a topic of longstanding interest in tumor virology. The basic idea is that the transient acquisition of a complete or incomplete viral genome may be sufficient to induce malignant conversion of host cells in vivo, resulting in neoplastic development. After eliciting a heritable change in the gene expression pattern of the host cell (initiation), the genomes of tumor viruses may be completely lost, i.e. in a hit and run-scenario they are not necessary for the maintenance of the malignant state. The expression of viral oncoproteins and RNAs may interfere not only with regulators of cell proliferation, but also with DNA repair mechanisms. DNA recombinogenic activities induced by tumor viruses or activated by other mechanisms may contribute to the secondary loss of viral genomes from neoplastic cells. Viral oncoproteins can also cause epigenetic dysregulation, thereby reprogramming cellular gene expression in a heritable manner. Thus, we expect that epigenetic scenarios of viral hit and run-tumorigenesis may facilitate new, innovative experiments and clinical studies in spite of the fact that the regular presence of a suspected human tumor virus in an early phase of neoplastic development and its subsequent regular loss have not been demonstrated yet. We propose that virus-specific “epigenetic signatures”, i.e. alterations of the host cell epigenome, especially altered DNA methylation patterns, may help to identify viral hit and run-oncogenic events, even after the complete loss of tumor viruses from neoplastic cells.     

Birth order and risk of nasopharyngeal carcinoma in multiplex families from Taiwan

A small proportion of individuals infected with Epstein–Barr virus (EBV) develop nasopharyngeal carcinoma (NPC). Timing of initial exposure could alter immunological responses to primary EBV infection and explain variation in cancer risk later in life. We measured early life family structure as a proxy for the timing of primary EBV infection to examine whether earlier age at infection alters NPC risk. We utilized data from 480 NPC cases and 1,291 unaffected siblings from Taiwanese NPC multiplex families (≥ 2 family members with NPC, N = 2,921). Information on birth order within the family was derived from questionnaires. We utilized logistic regression models to examine the association between birth order and NPC, accounting for correlations between relatives. Within these high‐risk families, older siblings had an elevated risk of NPC. Compared with being a first‐born child, the risk (95% CIs) of NPC associated with a birth order of two, three, four and five or more was 1.00 (0.71, 1.40), 0.88 (0.62, 1.24), 0.74 (0.53, 1.05) and 0.60 (0.43, 0.82), respectively (P for trend = 0.002). We observed no associations between NPC risk and the number of younger siblings or cumulative infant‐years exposure. These associations were not modified by underlying genetic predisposition or family size. We observed that early life family structure was important for NPC risk in NPC multiplex families, with older siblings having a greater risk of disease. Future studies focusing on more direct measures of the immune response to EBV in early childhood could elucidate the underlying mechanisms.     

皮肌炎合并鼻咽癌的研究进展

皮肌炎患者合并鼻咽癌的发病率高,可达10.8%-21.4%,两者伴发的机制可能有EB病毒感染、p53基因突变、免疫因素等,其高危因素包括恶性红斑、间质性肺炎、雷诺现象、肿瘤标志物水平增高、血沉加快、对糖皮质激素反应差等,其治疗以治疗鼻咽癌为主,皮肌炎症状会随着鼻咽癌的治疗而缓解。     

皮肌炎合并鼻咽癌的研究进展

皮肌炎患者合并鼻咽癌的发病率高,可达10.8%-21.4%,两者伴发的机制可能有EB病毒感染、p53基因突变、免疫因素等,其高危因素包括恶性红斑、间质性肺炎、雷诺现象、肿瘤标志物水平增高、血沉加快、对糖皮质激素反应差等,其治疗以治疗鼻咽癌为主,皮肌炎症状会随着鼻咽癌的治疗而缓解。     

EB病毒基因BARF1在鼻咽癌细胞中的表达及意义

目的：探讨EB(Epstein—Barr)病毒新基因BARF1(BamHI A rightward open reading frame1)在人鼻咽癌组织中的表达及意义，为深入阐明EB病毒致癌机制提供实验依据。方法：提取RNA后，采用RT—PCR方法扩增标本中的EBNA1(EB virus associated nuclear antigen 1)和BARF1 mRNA，PCR产物经2％琼脂糖凝胶电泳观察并照相。结果：11例RNA合格的标本均表达EBNA1，提示病例均为EB病毒阳性病例；其中9例表达BARF1，占82％：而且9例中的7例为强阳性。结论：EB病毒新基因BARF1 mRNA在鼻咽癌细胞中高表达，这提示除了已经明确的潜伏性膜蛋白1(LMP1)以外，BARF1可能在鼻咽癌细胞恶性增殖中发挥重要作用，具体机制有待深入研究。