Linkage of a nasopharyngeal carcinoma susceptibility locus to the HLA region

Molecular Diagnosis of Nasopharyngeal Carcinoma: Past and Future

Nasopharyngeal carcinoma (NPC) is a malignant tumor originated from the nasopharynx epithelial cells and has been linked with Epstein-Barr virus (EBV) infection, dietary habits, environmental and genetic factors. It is a common malignancy in Southeast Asia, especially with gender preference among men. Due to its non-specific symptoms, NPC is often diagnosed at a late stage. Thus, the molecular diagnosis of NPC plays a crucial role in early detection, treatment selection, disease monitoring, and prognosis prediction. This review aims to provide a summary of the current state and the latest emerging molecular diagnostic techniques for NPC, including EBV-related biomarkers, gene mutations, liquid biopsy, and DNA methylation. Challenges and potential future directions of NPC molecular diagnosis will be discussed.

Precision medicine in nasopharyngeal carcinoma: comprehensive review of past, present, and future prospect

Nasopharyngeal carcinoma (NPC) is an aggressive malignancy with high propensity for lymphatic spread and distant metastasis. It is prominent as an endemic malignancy in Southern China and Southeast Asia regions. Studies on NPC pathogenesis mechanism in the past decades such as through Epstein Barr Virus (EBV) infection and oncogenic molecular aberrations have explored several potential targets for therapy and diagnosis. The EBV infection introduces oncoviral proteins that consequently hyperactivate many promitotic pathways and block cell-death inducers. EBV infection is so prevalent in NPC patients such that EBV serological tests were used to diagnose and screen NPC patients. On the other hand, as the downstream effectors of oncogenic mechanisms, the promitotic pathways can potentially be exploited therapeutically. With the apparent heterogeneity and distinct molecular aberrations of NPC tumor, the focus has turned into a more personalized treatment in NPC. Herein in this comprehensive review, we depict the current status of screening, diagnosis, treatment, and prevention in NPC. Subsequently, based on the limitations on those aspects, we look at their potential improvements in moving towards the path of precision medicine. The importance of recent advances on the key molecular aberration involved in pathogenesis of NPC for precision medicine progression has also been reported in the present review. Besides, the challenge and future outlook of NPC management will also be highlighted.

EBV-induced T-cell responses in EBV-specific and nonspecific cancers

Epstein-Barr virus (EBV) is a ubiquitous human tumor virus associated with various malignancies, including B-lymphoma, NK and T-lymphoma, and epithelial carcinoma. It infects B lymphocytes and epithelial cells within the oropharynx and establishes persistent infection in memory B cells. With a balanced virus-host interaction, most individuals carry EBV asymptomatically because of the lifelong surveillance by T cell immunity against EBV. A stable anti-EBV T cell repertoire is maintained in memory at high frequency in the blood throughout persistent EBV infection. Patients with impaired T cell immunity are more likely to develop life-threatening lymphoproliferative disorders, highlighting the critical role of T cells in achieving the EBV-host balance. Recent studies reveal that the EBV protein, LMP1, triggers robust T-cell responses against multiple tumor-associated antigens (TAAs) in B cells. Additionally, EBV-specific T cells have been identified in EBV-unrelated cancers, raising questions about their role in antitumor immunity. Herein, we summarize T-cell responses in EBV-related cancers, considering latency patterns, host immune status, and factors like human leukocyte antigen (HLA) susceptibility, which may affect immune outcomes. We discuss EBV-induced TAA-specific T cell responses and explore the potential roles of EBV-specific T cell subsets in tumor microenvironments. We also describe T-cell immunotherapy strategies that harness EBV antigens, ranging from EBV-specific T cells to T cell receptor-engineered T cells. Lastly, we discuss the involvement of γδ T-cells in EBV infection and associated diseases, aiming to elucidate the comprehensive interplay between EBV and T-cell immunity.

The impact of HLA polymorphism on herpesvirus infection and disease

Human Leukocyte Antigens (HLA) are cell surface molecules, central in coordinating innate and adaptive immune responses, that are targets of strong diversifying natural selection by pathogens. Of these pathogens, human herpesviruses have a uniquely ancient relationship with our species, where coevolution likely has reciprocating impact on HLA and viral genomic diversity. Consistent with this notion, genetic variation at multiple HLA loci is strongly associated with modulating immunity to herpesvirus infection. Here, we synthesize published genetic associations of HLA with herpesvirus infection and disease, both from case/control and genome-wide association studies. We analyze genetic associations across the eight human herpesviruses and identify HLA alleles that are associated with diverse herpesvirus-related phenotypes. We find that whereas most HLA genetic associations are virus- or disease-specific, HLA-A*01 and HLA-A*02 allotypes may be more generally associated with immune susceptibility and control, respectively, across multiple herpesviruses. Connecting genetic association data with functional corroboration, we discuss mechanisms by which diverse HLA and cognate receptor allotypes direct variable immune responses during herpesvirus infection and pathogenesis. Together, this review examines the complexity of HLA-herpesvirus interactions driven by differential T cell and Natural Killer cell immune responses.

The Association between Infectious Mononucleosis and Cancer: A Cohort Study of 24,190 Outpatients in Germany

Background: Cancer represents one of the leading causes of death worldwide. Besides genetic risk factors and non-communicable diseases, chronic infections including Epstein−Barr virus (EBV) infection have been identified as promotors of cancer. In the present manuscript, we evaluated the association between infectious mononucleosis, the clinical manifestation of EBV infection, and cancer development in a real-word cohort of outpatients in Germany. Methods: We used the Disease Analyzer database (IQVIA) and matched a total of 12,095 patients with infectious mononucleosis to a cohort of individuals without infectious mononucleosis based on age, sex, index year, and annual patient consultation frequency between 2000 and 2018. Results: Patients diagnosed with infectious mononucleosis had a cancer incidence of 5.3 cases per 1000 person years versus 4.4 cases per 1000 person years for patients without infectious mononucleosis. In multivariable regression models, infectious mononucleosis showed a trend towards a higher incidence of cancer in general in the age group > 50 years (incidence rate ratio (IRR): 1.32; 95% CI: 1.04−1.67) and among men (IRR: 1.36; 95% CI: 1.07−1.72). Infectious mononucleosis was significantly associated with an increased incidence of tumors of the hematopoietic and lymphoid tissues (IRR: 1.75; 95% CI: 1.22−2.50) and showed a strong trend towards an association with prostate cancer (IRR: 3.09; 95% CI: 1.23−7.76). Conclusion: Infectious mononucleosis is associated with an increased incidence of certain cancer types. The present data from a large real-world cohort support the evidence on a role of EBV in the development of different malignancies and could trigger research efforts to further elucidate its precise involvement in the carcinogenic process.

Rare POLN mutations confer risk for familial nasopharyngeal carcinoma through weakened Epstein-Barr virus lytic replication

BACKGROUND

Nasopharyngeal carcinoma (NPC) exhibits significant familial aggregation; however, its susceptibility genes are largely unknown. Thus, this study aimed to identify germline mutations that might contribute to the risk of familial NPC, and explore their biological functions.

METHODS

Whole-exome sequencing was performed in 13 NPC pedigrees with multiple cases. Mutations co-segregated with disease status were further validated in a cohort composed of 563 probands from independent families, 2,953 sporadic cases, and 3,175 healthy controls. Experimental studies were used to explore the functions of susceptibility genes and their disease-related mutations.

FINDINGS

The three rare missense mutations in POLN (DNA polymerase nu) gene, P577L, R303Q, and F545C, were associated with familial NPC risk (5/576 [0·87%] in cases vs. 2/3374 [0·059%] in healthy controls with an adjusted OR of 44·84 [95% CI:3·91-514·34, p = 2·25 × 10^-3]). POLN was involved in Epstein-Barr virus (EBV) lytic replication in NPC cells in vitro. POLN promoted viral DNA replication, immediate-early and late lytic gene expression, and progeny viral particle production, ultimately affecting the proliferation of host cells. The three mutations were located in two pivotal functional domains and were predicted to alter the protein stability of POLN in silico. Further assays demonstrated that POLN carrying any of the three mutations displayed reduced protein stability and decreased expression levels, thereby impairing its ability to promote complete EBV lytic replication and facilitate cell survival.

INTERPRETATION

We identified a susceptibility gene POLN for familial NPC and elucidated its function.

FUNDING

This study was funded by the National Key Research and Development Program of China (2021YFC2500400); the National Key Research and Development Program of China (2020YFC1316902); the Basic and Applied Basic Research Foundation of Guangdong Province, China (2021B1515420007); the National Natural Science Foundation of China (81973131); the National Natural Science Foundation of China (82003520); the National Natural Science Foundation of China (81903395).

Nasopharyngeal carcinoma: an evolving paradigm

The past three decades have borne witness to many advances in the understanding of the molecular biology and treatment of nasopharyngeal carcinoma (NPC), an Epstein-Barr virus (EBV)-associated cancer endemic to southern China, southeast Asia and north Africa. In this Review, we provide a comprehensive, interdisciplinary overview of key research findings regarding NPC pathogenesis, treatment, screening and biomarker development. We describe how technological advances have led to the advent of proton therapy and other contemporary radiotherapy approaches, and emphasize the relentless efforts to identify the optimal sequencing of chemotherapy with radiotherapy through decades of clinical trials. Basic research into the pathogenic role of EBV and the genomic, epigenomic and immune landscape of NPC has laid the foundations of translational research. The latter, in turn, has led to the development of new biomarkers and therapeutic targets and of improved approaches for individualizing immunotherapy and targeted therapies for patients with NPC. We provide historical context to illustrate the effect of these advances on treatment outcomes at present. We describe current preclinical and clinical challenges and controversies in the hope of providing insights for future investigation.

Current Status and Future Perspectives about Molecular Biomarkers of Nasopharyngeal Carcinoma

Simple Summary

Nasopharyngeal carcinoma is a serious major public health problem in its endemic countries. Up to 80% of NPC patients with locally advanced disease or distant metastasis at diagnosis were associated with poor prognosis and with median survival less than 4 months. The mortality rate of NPC metastasis is up to 91%. To date, there is no available curative treatment or reliable early diagnosis or prognosis for NPC. Discovery and development of reliable early diagnosis and prognosis biomarkers for nasopharyngeal carcinoma are urgent needed. Hence, we have here listed the potential early diagnosis and prognosis biomarker candidates for nasopharyngeal carcinoma. This review will give an insight to readers on the progress of NPC biomarker discovery to date, as well as future prospective biomarker development and their translation to clinical use.

Abstract

Nasopharyngeal carcinoma (NPC) is an epithelial malignancy that shows a remarkable ethnic and geographical distribution. It is one of the major public health problems in some countries, especially Southern China and Southeast Asia, but rare in most Western countries. Multifactorial interactions such as Epstein–Barr virus infection, individual’s genetic susceptibility, as well as environmental and dietary factors may facilitate the pathogenesis of this malignancy. Late presentation and the complex nature of the disease have led it to become a major cause of mortality. Therefore, an effective, sensitive, and specific molecular biomarker is urgently needed for early disease diagnosis, prognosis, and prediction of metastasis and recurrence after treatment. In this review, we discuss the recent research status of potential biomarker discovery and the problems that need to be explored further for better NPC management. By studying the aberrant pattern of these candidate biomarkers that promote NPC development and progression, we are able to understand the complexity of this malignancy better, hence positing our stands better towards strategies that may provide a way forward to the discovery of more reliable and specific biomarkers for diagnosis and targeted therapeutic development.

Association between HLA alleles and Epstein-Barr virus Zta-IgA serological status in healthy males from southern China

Background

Nasopharyngeal carcinoma (NPC), an Epstein–Barr virus (EBV) associated cancer, exhibits an extremely high incidence in southern Chinese. Given that human leukocyte antigen (HLA) plays critical roles in antigen presentation and relates to NPC susceptibility, it is speculated that certain HLA variants may affect EBV reactivation, which is a key pathogenic factor of NPC. Therefore, we attempted to identify HLA alleles associated with the indicator of EBV reactivation, Zta‐IgA, in healthy males from NPC endemic area.

Methods

HLA alleles of 1078 healthy males in southern China from the 21‐RCCP study were imputed using genome‐wide single nucleotide polymorphism data. EBV Zta‐IgA in blood samples were measured using an enzyme‐linked immunosorbent assay. Multiple logistic regression analysis was used to evaluate the effect of HLA allele on Zta‐IgA serological status and its potential joint association with smoking. The binding affinity for Zta‐peptide was predicted using NetMHCIIpan 4.0.

Results

HLA‐DRB1*09:01 was found to be associated with a higher risk of Zta‐IgA seropositivity (odds ratio = 1.80, 95% confidence interval = 1.32–2.45; p = 1.82 × 10⁻⁴). Compared with non‐smokers without HLA‐DRB1*09:01, the effect size increased to 2.19‐ and 3.70‐fold for the light and heavy smokers carrying HLA‐DRB1*09:01, respectively. Furthermore, HLA‐DRB1*09:01 showed a stronger binding affinity to Zta peptide than other HLA‐DRB1 alleles.

Conclusions

Our study highlighted the pivotal role of genetic HLA variants in EBV reactivation and the etiology of NPC. Smokers with HLA‐DRB1*09:01 have a significantly higher risk of being Zta‐IgA seropositive, which indicates the necessity of smoking cessation in certain high‐risk populations and also provide clues for further research on the etiology of NPC.

The Evolving Epidemiology of Nasopharyngeal Carcinoma

BACKGROUND

The epidemiology of nasopharyngeal carcinoma (NPC) has long been a source of fascination due to the malignancy's striking geographic distribution, the involvement of the oncogenic Epstein-Barr virus (EBV), the unique association with intake of Chinese-style salt-preserved fish, and etiologic heterogeneity by histologic subtype.

METHODS

This review summarizes the current epidemiologic literature on NPC, highlighting recent results from our population-based case-control study in southern China.

RESULTS

Findings from our case-control study provide new insight into the epidemiology of NPC, including a diminished role of Chinese-style salt-preserved fish, a profound impact of EBV genetic sequence variation, modest positive associations with passive smoking and household air pollution, and possible effects of oral health and the oral microbiome. Recent findings from other studies include a protective association with infectious mononucleosis, suggesting a causal role of early EBV infection; familial risk conferred by shared genetic variation in the host antibody-mediated immune response to EBV infection; and an unclear association with occupational exposure to formaldehyde.

CONCLUSIONS

To shed further light on the interplay of environmental, genetic, and viral causes of NPC, large pooled studies must accumulate sufficient cases with detailed exposure data.

IMPACT

New epidemiologic findings have reshaped the causal model for NPC.

Nasopharyngeal Epstein-Barr virus DNA loads in high-risk nasopharyngeal carcinoma families: Familial aggregation and host heritability

Nasopharyngeal carcinoma (NPC), the most common head and neck cancer, is characterized by distinct geographic distribution and familial aggregation. Multiple risk factors, including host genetics, environmental factor, and EBV infection, have been linked to the development of NPC, particularly in the familial clustering cases. However, the cause of NPC endemicity remains enigmatic due possibly to the complicated interplay between these risk factors. Recently, positive Epstein-Barr virus (EBV) DNA loads at nasopharyngeal (NP) cavity has been found to reflect NPC development and applied in NPC screening. To examine whether the increased NP EBV loads could aggregate in the families and be affected by host genetics and environmental factor, EBV loads were obtained by 510 NP brushing samples from eligible unaffected individuals, who have two or more relatives affected with NPC, in 116 high-risk NPC families. The correlation of relative pairs was estimated using S.A.G.E. (version 6.4, 2016), and host heritability of NP EBV loads was calculated with variance component models using SOLAR (version 8.4.2, 2019). In result, significant correlations of EBV loads were observed between parent-offspring pairs and sibling-sibling pairs (P < .001), but not in distant kin relationship pairs. Interestingly, after excluding the shared environmental factor within families, host genetics contributes significantly to NP EBV loads with a heritability of 56.41% (P = 1.00 × 10-7 ), and its effect was slightly elevated (68.86%, P = 3.40 × 10-6 ) in families with more NPC cases (≥3). These findings indicate that additional host-genetic variants involved in the EBV local NP mucosal behavior may be especially important for the development of NPC.

The head and neck cancer genome in the era of immunotherapy

The recent success of immunotherapy in head and neck squamous cell carcinoma (HNSCC) has necessitated a new perspective on the cancer genome. Here we review recent advances in the carcinogenesis and molecular genetics of HNSCC with an eye on their implications for cancer immunity. Newer sequencing technologies have recently facilitated dissection of the complex interaction between the HPV virus, tumor, host factors, and the tumor microenvironment (TME) that help shed light on how the immune system interacts with head and neck malignancies.

Novel Therapies Boosting T Cell Immunity in Epstein Barr Virus-Associated Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is a malignant tumour of the head and neck affecting localised regions of the world, with the highest rates described in Southeast Asia, Northern Africa, and Greenland. Its high morbidity rate is linked to both late-stage diagnosis and unresponsiveness to conventional anti-cancer treatments. Multiple aetiological factors have been described including environmental factors, genetics, and viral factors (Epstein Barr Virus, EBV), making NPC treatment that much more complex. The most common forms of NPCs are those that originate from the epithelial tissue lining the nasopharynx and are often linked to EBV infection. Indeed, they represent 75–95% of NPCs in the low-risk populations and almost 100% of NPCs in high-risk populations. Although conventional surgery has been improved with nasopharyngectomy’s being carried out using more sophisticated surgical equipment for better tumour resection, recent findings in the tumour microenvironment have led to novel treatment options including immunotherapies and photodynamic therapy, able to target the tumour and improve the immune system. This review provides an update on the disease’s aetiology and the future of NPC treatments with a focus on therapies activating T cell immunity.

Prognostic significance of human papillomavirus and Epstein-Bar virus in nasopharyngeal carcinoma

BACKGROUND

The clinical significance of Epstein-Barr virus (EBV) and human papillomavirus (HPV) infection in nasopharyngeal carcinoma (NPC) is unclear.

METHODS

Three hundred and forty three patients with NPC diagnosed between 1998 and 2017 and treated at our institution were included. Chi-square was used to identify characteristics associated with viral status. Kaplan-Meier methods were used to estimate overall survival (OS) and Cox proportional regression was used to identify prognostic factors.

RESULTS

Patients with HPV-associated NPC were more likely to have a positive smoking history and to present at a higher T classification. At a median follow-up time of 59.9 months (range: 0.1-222.4 months), there were no differences in OS (P = .198), time to local failure (LF, P = .403), or time to distant metastasis (DM, P = .849) between the viral subgroups. Older age (hazard ratio [HR]: 2.242, 95% confidence interval [CI] 1.374-3.659, P = .001) and higher overall stage (HR: 2.047, 95% CI 1.235-3.391, P = .005) were prognostic for worse OS.

CONCLUSION

In our population, viral status was not prognostic for OS, LF, or DM.

Epstein-Barr Virus and the Human Leukocyte Antigen Complex

Purpose

While most adults are infected Epstein-Barr virus (EBV), 3-5% remain uninfected. The human leukocyte antigen (HLA) complex, which controls many pathogens, may influence infection and disease associated with EBV.

Recent Findings

Numerous EBV proteins and miRNAs down-regulate HLA class I and II expression on the cell surface. HLA class II functions as a receptor for EBV entry into B cells. Specific HLA class II alleles correlate with the susceptibility of B cells to EBV infection in vitro and with EBV seropositivity or seronegativity of humans. HLA class I polymorphisms correlate with development and severity of EBV infectious mononucleosis and with the risk of several virus-associated malignancies including nasopharyngeal carcinoma, Hodgkin lymphoma, and post-transplant lymphoproliferative disease.

Significance

These findings indicate that while EBV has evolved to use MHC class II as a receptor for virus entry, polymorphisms in MHC class II and class I influence virus infection and disease.

Does East meet West? Towards a unified vision of the management of Nasopharyngeal carcinoma

Nasopharyngeal cancer (NPC) is notable for its wide geographic variation, with incidences as high as 30 in 100,000 in endemic regions but < 1 in 100,000 worldwide. This review aims to identify areas where there could be differences in prognosis, management or outcomes among countries with high or low incidence of NPC. The incidence has generally declined both in endemic and non-endemic regions throughout the years, which may be attributed to the decrease in exposure to risk factors such as early exposure to salted fish and smoking. Ethnicity has an impact both on incidence and prognosis, with Southeast Asians having the highest incidence but also better survival. Concurrent chemoradiotherapy, with or without adjuvant and/or induction chemotherapy, is the standard of care for locoregionally advanced disease, as reflected in clinical practice guidelines. Despite improvements in management, a proportion of patients relapse. Salvage treatment is associated with significant morbidity due to the critical location of the nasopharynx and the toxicities of initial therapy. Clinical expertise is paramount, but is easier to attain in endemic regions and high volume centers where enrollment of patients in clinical trials is more feasible. Collaboration between low and high incidence countries and between low and high volume facilities is key to improving NPC prognosis worldwide.

Systematic Review and Meta-analysis of SNPs from Genome-Wide Association Studies of Head and Neck Cancer

Objective Various genome-wide association studies (GWASs) identified new head and neck cancer (HNC) susceptibility loci, although the evidence has not been systematically summarized. We performed a systematic review and meta-analyses of the GWASs to identify the most commonly reported genetic loci associated with a risk of HNC. Data Sources We searched the PubMed, ISI Web of Science, SCOPUS, and GWAS databases to retrieve eligible studies, in English or Italian, published until June 1, 2017. Review Methods Only GWASs reporting data on the association between single-nucleotide polymorphisms (SNPs) and HNC were included. The quality of included studies was evaluated using the Q-Genie tool. Random-effect meta-analyses were performed considering only SNPs with at least 1 significant result from the included articles, and pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Results Seven studies of case-control design were included in the review. Five studies on nasopharyngeal cancer (NPC) in Chinese, reporting on 27 different SNPs, were included in meta-analyses. Results show that 6 SNPs ( rs2076483, rs2975042, rs9258122, rs29232, and rs9510787) had an increased pooled estimates for A risk alleles (OR [95% CI]: 1.55 [1.36-1.77], 1.90 [1.69-2.14], 1.47 [1.31-1.65], 1.52 [1.32-1.76], and 1.22 [1.13-1.31], respectively) while G risk allele of rs3129055 reported an OR of 1.49 (95% CI, 1.33-1.67). Conclusion Our systematic review identified 5 SNPs located on chromosome 6 ( rs2076483, rs2975042, rs3129055, rs9258122, and rs29232) and 1 ( rs9510787) on chromosome 13 as significantly associated with an increased risk of NPC in Chinese.

What has GWAS done for HLA and disease associations?

The major histocompatibility complex (MHC) is located in chromosome 6p21 and contains crucial regulators of immune response, including human leucocyte antigen (HLA) genes, alongside other genes with nonimmunological roles. More recently, a repertoire of noncoding RNA genes, including expressed pseudogenes, has also been identified. The MHC is the most gene dense and most polymorphic part of the human genome. The region exhibits haplotype-specific linkage disequilibrium patterns, contains the strongest cis- and trans-eQTLs/meQTLs in the genome and is known as a hot spot for disease associations. Another layer of complexity is provided to the region by the extreme structural variation and copy number variations. While the HLA-B gene has the highest number of alleles, the HLA-DR/DQ subregion is structurally most variable and shows the highest number of disease associations. Reliance on a single reference sequence has complicated the design, execution and analysis of GWAS for the MHC region and not infrequently, the MHC region has even been excluded from the analysis of GWAS data. Here, we contrast features of the MHC region with the rest of the genome and highlight its complexities, including its functional polymorphisms beyond those determined by single nucleotide polymorphisms or single amino acid residues. One of the several issues with customary GWAS analysis is that it does not address this additional layer of polymorphisms unique to the MHC region. We highlight alternative approaches that may assist with the analysis of GWAS data from the MHC region and unravel associations with all functional polymorphisms beyond single SNPs. We suggest that despite already showing the highest number of disease associations, the true extent of the involvement of the MHC region in disease genetics may not have been uncovered.

The Microenvironment in Epstein-Barr Virus-Associated Malignancies

The Epstein–Barr virus (EBV) can cause a wide variety of cancers upon infection of different cell types and induces a highly variable composition of the tumor microenvironment (TME). This TME consists of both innate and adaptive immune cells and is not merely an aspecific reaction to the tumor cells. In fact, latent EBV-infected tumor cells utilize several specific mechanisms to form and shape the TME to their own benefit. These mechanisms have been studied largely in the context of EBV+ Hodgkin lymphoma, undifferentiated nasopharyngeal carcinoma, and EBV+ gastric cancer. This review describes the composition, immune escape mechanisms, and tumor cell promoting properties of the TME in these three malignancies. Mechanisms of susceptibility which regularly involve genes related to immune system function are also discussed, as only a small proportion of EBV-infected individuals develops an EBV-associated malignancy.

The biological properties of different Epstein-Barr virus strains explain their association with various types of cancers

The Epstein-Barr virus (EBV) is etiologically associated with the development of multiple types of tumors, but it is unclear whether this diversity is due to infection with different EBV strains. We report a comparative characterization of SNU719, GP202, and YCCEL1, three EBV strains that were isolated from gastric carcinomas, M81, a virus isolated in a nasopharyngeal carcinoma and several well-characterized laboratory type A strains. We found that B95-8, Akata and GP202 induced cell growth more efficiently than YCCEL1, SNU719 and M81 and this correlated positively with the expression levels of the viral BHRF1 miRNAs. In infected B cells, all strains except Akata and B95-8 induced lytic replication, a risk factor for carcinoma development, although less efficiently than M81. The panel of viruses induced tumors in immunocompromised mice with variable speed and efficacy that did not strictly mirror their in vitro characteristics, suggesting that additional parameters play an important role. We found that YCCEL1 and M81 infected primary epithelial cells, gastric carcinoma cells and gastric spheroids more efficiently than Akata or B95-8. Reciprocally, Akata and B95-8 had a stronger tropism for B cells than YCCEL1 or M81. These data suggest that different EBV strains will induce the development of lymphoid tumors with variable efficacy in immunocompromised patients and that there is a parallel between the cell tropism of the viral strains and the lineage of the tumors they induce. Thus, EBV strains can be endowed with properties that will influence their transforming abilities and the type of tumor they induce.

Monocyte-derived factors including PLA2G7 induced by macrophage-nasopharyngeal carcinoma cell interaction promote tumor cell invasiveness

The non-keratinizing undifferentiated subtype of nasopharyngeal carcinoma (NPC) is a malignancy characterized by an intimate relationship between neoplastic cells and a non-neoplastic lymphoid component. Tumor-associated macrophages (TAMs) foster tumor progression through production of soluble mediators that support proliferation, angiogenesis, survival and invasion of malignant cells. However, the role of macrophages in the progression of NPC remains poorly understood. This study aims to investigate the functional and phenotypic changes that occur to macrophages in macrophage-NPC cell co-culture systems, and how these changes influence tumor cells. We found that monocytes, including THP-1 cells and primary human monocytes, co-cultured with C666-1 NPC cells upregulate expression of pro-inflammatory cytokines at the early stages, followed by the induction of metastasis-related genes and interferon-stimulated genes at the later stage of coculture, indicating that TAMs are “educated” by NPC cells for cancer progression. Importantly, the induction of these factors from the TAMs was also found to enhance the migratory capabilities of the NPC cells. We have also identified one of these macrophage-derived factor, phospholipase A2 Group 7 (PLA2G7), to be important in regulating tumor cell migration and a novel tumor-promoting factor in NPC. Further studies to characterize the role of PLA2G7 in tumor metastasis may help determine its potential as a therapeutic target in NPC.

Nasopharyngeal carcinoma super-enhancer-driven ETV6 correlates with prognosis

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

Familial aggregation of nasopharyngeal carcinoma in Taiwan

BACKGROUND

The incidence of nasopharyngeal carcinoma (NPC) is higher in Chinese than in Caucasian populations. Genetic, viral, and lifestyle factors may explain these ethnic differences in the incidence of NPC. In the present study, we examined the familial aggregation, heritability, and relative risks (RRs) of NPC using a nationwide database in Taiwan.

METHODS

A population-based family study was conducted using the Taiwan National Health Insurance Research Database. Participants included all individuals (N=23,422,955) registered with that database in 2013; of these, 17,653 had NPC. Among them, 47.45%, 57.45%, 47.29%, and 1.51% had a parent, child, sibling, and twin, respectively, with NPC.

RESULTS

Among the approximately 23 million Taiwan NHI beneficiaries in 2013, the relative risks (RRs) (95% confidence intervals) for NPC were 34.46 (5.12-231.77) for twins of the patients, 9.23 (6.34-13.43) for siblings, 3.80 (2.97-4.86) for parents, 3.74 (2.60-5.37) for offspring, and 1.78 (1.16-2.74) for spouses without genetic similarity. The mean age of onset in first-degree relative-affected NPC patients was 35.5years compared to 39.0years for NPC patients without affected first-degree relatives (p≤0.0001). Using a threshold liability model, the accountability for phenotypic variance of NPC was estimated to be 61.3% for genetic factors (heritability), 13.9% for shared environmental factors, and 24.8% for non-shared environmental factors. The probability of a patient with NPC to be sporadic was 82.8%.

CONCLUSION

This population-based analysis suggested a strong familial tendency in the development of NPC. Screening of first-degree relatives of NPC patients is recommended, particularly in endemic regions.

The interplay of host genetic factors and Epstein-Barr virus in the development of nasopharyngeal carcinoma

The interplay between host cell genetics and Epstein-Barr virus (EBV) infection contributes to the development of nasopharyngeal carcinoma (NPC). Understanding the host genetic and epigenetic alterations and the influence of EBV on cell signaling and host gene regulation will aid in understanding the molecular pathogenesis of NPC and provide useful biomarkers and targets for diagnosis and therapy. In this review, we provide an update of the oncogenes and tumor suppressor genes associated with NPC, as well as genes associated with NPC risk including those involved in carcinogen detoxification and DNA repair. We also describe the importance of host genetics that govern the human leukocyte antigen (HLA) complex and immune responses, and we describe the impact of EBV infection on host cell signaling changes and epigenetic regulation of gene expression. High-power genomic sequencing approaches are needed to elucidate the genetic basis for inherited susceptibility to NPC and to identify the genes and pathways driving its molecular pathogenesis.

Sequence analysis of EBV immune evasion gene BNLF2a in EBV associated tumors and healthy individuals from nasopharyngeal carcinoma endemic and non-endemic regions of China

BNLF2a is an Epstein-Barr virus (EBV) immune evasion gene. Its protein is located in the endoplasmic reticulum (ER) membrane, and can inhibit the antigen transporting function of TAP, thereby perturbing the immune response to EBV in lytic and prelatent phase. In order to explore whether the polymorphism of BNLF2a gene has a role in different types of EBV associated tumors, we conducted complete sequencing of the gene BNLF2a in 408 cases of EBV positive tumors (76 lymphomas, 45 gastric carcinomas, and 85 nasopharyngeal carcinomas in northern China and 27 lymphomas, 30 gastric carcinomas, and 57 nasopharyngeal carcinomas in southern China) and throat washings from healthy individuals (39 in northern China and 49 in southern China). Two main variant types of BNLF2a were identified. Type BNLF2a-A, which was similar to B95-8, was dominant in all sub-populations (66.7-100%) in this study. Type BNLF2a-B was characterized by the mutations at position 8 and 40. The variation patterns of BNLF2a were significantly different between samples from northern and southern China (P < 0.05), and between the tumors and healthy donor samples from the northern China (P < 0.0167). Type BNLF2a-B was more frequent in healthy donors of northern China (33.3%), and the proportion of this type was higher in the northern than in the southern NPCs. These data demonstrate that the BNLF2a gene is highly conserved, and its polymorphism is geographically restricted. Type BNLF2a-B is more prevalent in northern China and may be less tumor transformative.

Effect of nasopharyngeal carcinoma-derived exosomes on human regulatory T cells

BACKGROUND

Regulatory T cells (Treg) and tumor-exosomes are thought to play a role in preventing the rejection of malignant cells in patients bearing nasopharyngeal carcinoma (NPC).

METHODS

Treg recruitment by exosomes derived from NPC cell lines (C15/C17-Exo), exosomes isolated from NPC patients' plasma (Patient-Exo), and CCL20 were tested in vitro using Boyden chamber assays and in vivo using a xenograft SCID mouse model (n = 5), both in the presence and absence of anti-CCL20 monoclonal antibodies (mAb). Impact of these NPC exosomes (NPC-Exo) on Treg phenotype and function was determined using adapted assays (FACS, Q-PCR, ELISA, and MLR). Experiments were performed in comparison with exosomes derived from plasma of healthy donors (HD-Exo). The Student's t test was used for group comparisons. All statistical tests were two-sided.

RESULTS

CCL20 allowed the intratumoral recruitment of human Treg. NPC-Exo also facilitated Treg recruitment (3.30 ± 0.34 fold increase, P < .001), which was statistically significantly inhibited (P < .001) by an anti-CCL20 blocking mAb. NPC-Exo also recruited conventional CD4(+)CD25(-) T cells and mediated their conversion into inhibitory CD4(+)CD25(high) cells. Moreover, NPC-Exo enhanced (P = .0048) the expansion of human Treg, inducing the generation of Tim3(Low) Treg with increased expression of CD25 and FOXP3. Finally, NPC-Exo induced an overexpression of cell markers associated with Treg phenotype, properties and recruitment capacity. For example, GZMB mean fold change was 21.45 ± 1.75 (P < .001). These results were consistent with a stronger suppression of responder cells' proliferation and the secretion of immunosuppressive cytokines (IL10, TGFB1).

CONCLUSION

Interactions between NPC-Exo and Treg represent a newly defined mechanism that may be involved in regulating peripheral tolerance by tumors and in supporting immune evasion in human NPC.

Control of the inflammatory response mechanisms mediated by natural and induced regulatory T-cells in HCV-, HTLV-1-, and EBV-associated cancers

Virus infections are involved in chronic inflammation and, in some cases, cancer development. Although a viral infection activates the immune system's response that eradicates the pathogen mainly through inflammatory mechanisms, it is now recognized that this inflammatory condition is also favorable to the development of tumors. Indeed, it is well described that viruses, such as hepatitis C virus (HCV), Epstein Barr virus (EBV), human papillomavirus (HPV) or human T-cell lymphotropic virus type-1 (HTLV-1), are important risk factors for tumor malignancies. The inflammatory response is a fundamental immune mechanism which involves several molecular and cellular components consisting of cytokines and chemokines that are released by various proinflammatory cells. In parallel to this process, some endogenous recruited components release anti-inflammatory mediators to restore homeostasis. The development of tools and strategies using viruses to hijack the immune response is mostly linked to the presence of regulatory T-cells (Treg) that can inhibit inflammation and antiviral responses of other effector cells. In this review, we will focus on current understanding of the role of natural and induced Treg in the control and the resolution of inflammatory response in HCV-, HTLV-1-, and EBV-associated cancers.

Evaluation and integration of genetic signature for prediction risk of nasopharyngeal carcinoma in Southern China

Genetic factors, as well as environmental factors, play a role in development of nasopharyngeal carcinoma (NPC). A number of single nucleotide polymorphisms (SNPs) have been reported to be associated with NPC. To confirm these genetic associations with NPC, two independent case-control studies from Southern China comprising 1166 NPC cases and 2340 controls were conducted. Seven SNPs in ITGA9 at 3p21.3 and 9 SNPs within the 6p21.3 HLA region were genotyped. To explore the potential clinical application of these genetic markers in NPC, we further evaluate the predictive/diagnostic role of significant SNPs by calculating the area under the curve (AUC). Results. The reported associations between ITGA9 variants and NPC were not replicated. Multiple loci of GABBR1, HLA-F, HLA-A, and HCG9 were statistically significant in both cohorts (P_combined range from 5.96 × 10⁻¹⁷ to 0.02). We show for the first time that these factors influence NPC development independent of environmental risk factors. This study also indicated that the SNP alone cannot serve as a predictive/diagnostic marker for NPC. Integrating the most significant SNP with IgA antibodies status to EBV, which is presently used as screening/diagnostic marker for NPC in Chinese populations, did not improve the AUC estimate for diagnosis of NPC.

Oncogene mutational profile in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a common tumor in Southern China, but the oncogene mutational status of NPC patients has not been clarified. Using time-of-flight mass spectrometry, 238 mutation hotspots in 19 oncogenes were examined in 123 NPC patients. The relationships between mutational status and clinical data were assessed with a χ² or Fisher’s exact test. Survival analysis was performed using the Kaplan–Meier method with the log-rank test. In 123 patients, 21 (17.1%) NPC tumors were positive for mutations in eight oncogenes: six patients had PIK3CA mutations (4.9%), five NRAS mutations (4.1%), four KIT mutations (3.3%), two PDGFRA mutations (1.6%), two ABL mutations (1.6%), and one with simultaneous mutations in HRAS, EGFR, and BRAF (1%). Patients with mutations were more likely to relapse or develop metastasis than those with wild-type alleles (P=0.019). No differences or correlations were found in other clinical characteristics or in patient survival. No mutations were detected in oncogenes AKT1, AKT2, CDK, ERBB2, FGFR1, FGFR3, FLT3, JAK2, KRAS, MET, and RET. These results demonstrate an association between NPC and mutations in NRAS, KIT, PIK3CA, PDGFRA, and ABL, which are associated with patient relapse and metastasis.

Etiological factors of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a common disease among southern Chinese. The major etiological factors proposed for NPC pathogenesis include genetic susceptibility, environment factors and EBV infection. In the high risk population, genetic susceptibility to NPC has been mapped to the HLA loci and adjacent genes in MHC region on chromosome 6p21. Consumption of preserved food including salted fish has been implicated in its etiology in earlier studies. Its contribution to pathogenesis of NPC remains to be determined. A decreasing trend of NPC incidence was observed in Hong Kong, Taiwan and Singapore in recent years which may be accounted by a change of dietary habits. A comprehensive epidemiological study will help to elucidate the relative importance of various risk factors in the pathogenesis of NPC. Despite the close association of EBV infection with NPC, the etiological role of EBV in NPC pathogenesis remains enigmatic. EBV infection in primary nasopharyngeal epithelial cells is uncommon and difficult to achieve. EBV does not transform primary nasopharyngeal epithelial cells into proliferative clones, which contrasts greatly with the well-documented ability of EBV to transform and immortalize primary B cells. Genetic alterations identified in premalignant nasopharyngeal epithelium may play crucial roles to support stable EBV infection. Subsequently, latent and lytic EBV gene products may drive clonal expansion and transformation of premalignant nasopharyngeal epithelial cells into cancer cells. Stromal inflammation in nasopharyngeal mucosa is believed to play an important role in modulating the growth and possibly drive the malignant transformation of EBV-infected nasopharyngeal epithelial cells. Furthermore, there are increasing evidences supporting a role of EBV infection to evade host immune surveillance. EBV-infected cells may have selective growth advantages in vivo by acquiring a stress-resistance phenotype. Understanding the etiological factors and pathogenesis of NPC will contribute effectively to the prevention and treatment of this disease.

Human leukocyte antigens and epstein-barr virus-associated nasopharyngeal carcinoma: old associations offer new clues into the role of immunity in infection-associated cancers

Nasopharyngeal carcinoma (NPC) is an Epstein–Barr virus (EBV) associated tumor. In addition to EBV, host genetic factors are believed to be important determinants of NPC risk. Of all genes studies to date, human leukocyte antigen (HLA) genes have shown the most consistent evidence for association with NPC, both from candidate-gene studies and genome-wide association studies (GWAS). In this report we summarize results from recent studies that evaluated the association between HLA and NPC, and discuss whether findings reflect direct causal associations for HLA genes and/or indirect associations that mark causal associations with other genes in the gene-dense major histocompatibility (MHC) region where HLA resides. We also compare GWAS results across cancer sites for which strong hits in the MHC region were observed to generate new hypotheses regarding the role of HLA genes in the development of EBV-associated cancers such as NPC. Of note, we report that MHC associations for EBV-associated cancers (NPC, EBV+ Hodgkin lymphoma) are driven by HLA class I genes. In contrast, MHC associations for other viral-associated cancers (cervical cancer, hepatocellular carcinoma) or other hematopoetic cancers (EBV− Hodgkin lymphoma, leukemia, non-Hodgkin lymphomas) are driven by HLA class II genes, and those for other solid tumors with less clear links to infections (lung, testicular, prostate cancers) are driven by non-HLA genes in the MHC region. Future studies should aim to better understand these patterns.

Spontaneous lytic replication and epitheliotropism define an Epstein-Barr virus strain found in carcinomas

The Epstein-Barr virus (EBV) is found in a variety of tumors whose incidence greatly varies around the world. A poorly explored hypothesis is that particular EBV strains account for this phenomenon. We report that M81, a virus isolated from a Chinese patient with nasopharyngeal carcinoma (NPC), shows remarkable similarity to other NPC viruses but is divergent from all other known strains. M81 exhibited a reversed tropism relative to common strains with a reduced ability to infect B cells and a high propensity to infect epithelial cells, which is in agreement with its isolation from carcinomas. M81 spontaneously replicated in B cells in vitro and in vivo at unusually high levels, in line with the enhanced viral replication observed in NPC patients. Spontaneous replication and epitheliotropism could be partly ascribed to polymorphisms within viral proteins. We suggest considering M81 and its closely related isolates as an EBV subtype with enhanced pathogenic potential.

Genetic variants of heat shock protein A1L2437 and A1B1267 as possible risk factors for hepatocellular carcinoma in India

To study the role of heat shock protein A1L (HSPA1L) and A1B (HSPA1B) polymorphisms and subsequent risk of hepatocellular carcinoma (HCC) in India. Subjects enrolled included 185 cases of HCC, 182 cases of chronic hepatitis (CH) and 200 healthy controls. Genomic DNA was typed for HSPA1L2437 and HSPA1B1267 SNP using polymerase chain reaction with restriction fragment length polymorphism. Other risk factors were also analysed. Hepatitis B virus (HBV) infection, older age >35 years and high aflatoxin level in urine increased the risk of HCC. The frequencies of HSPA1L BB genotype and B allele in HCC were more than in CH [odds ratio (OR): 9.83; P = 0.000], but also in HBV-related HCC than Chronic Hepatitis B (CHB) [OR: 3.44; P = 0.004] and HCV-related HCC compared to CHC [OR: 6.32; P = 0.010]. The frequency of HSPA1B genotype in the homozygous state was more in CH [OR: 6.01; P = 0.001] and is a good marker to predict the risk of HCV-related CH (CHC) compared to controls. HCV-related HCC has a higher frequency of the B allele of HSPA1B than healthy controls [OR: 3.95; P = 0.000] and CHC [OR: 2.35; P = 0.000], respectively. The frequencies increased further significantly in CHC compared to healthy controls [OR: 9.26; P = 0.000]. The risk for the development of CH and HCC compared to healthy controls irrespective of the aetiology was significant in terms of the HSPA1B marker than HSPA1L in the Indian population.

Developing genetic epidemiological models to predict risk for nasopharyngeal carcinoma in high-risk population of China

To date, the only established model for assessing risk for nasopharyngeal carcinoma (NPC) relies on the sero-status of the Epstein-Barr virus (EBV). By contrast, the risk assessment models proposed here include environmental risk factors, family history of NPC, and information on genetic variants. The models were developed using epidemiological and genetic data from a large case-control study, which included 1,387 subjects with NPC and 1,459 controls of Cantonese origin. The predictive accuracy of the models were then assessed by calculating the area under the receiver-operating characteristic curves (AUC). To compare the discriminatory improvement of models with and without genetic information, we estimated the net reclassification improvement (NRI) and integrated discrimination index (IDI). Well-established environmental risk factors for NPC include consumption of salted fish and preserved vegetables and cigarette smoking (in pack years). The environmental model alone shows modest discriminatory ability (AUC = 0.68; 95% CI: 0.66, 0.70), which is only slightly increased by the addition of data on family history of NPC (AUC = 0.70; 95% CI: 0.68, 0.72). With the addition of data on genetic variants, however, our model’s discriminatory ability rises to 0.74 (95% CI: 0.72, 0.76). The improvements in NRI and IDI also suggest the potential usefulness of considering genetic variants when screening for NPC in endemic areas. If these findings are confirmed in larger cohort and population-based case-control studies, use of the new models to analyse data from NPC-endemic areas could well lead to earlier detection of NPC.

The principal genetic determinants for nasopharyngeal carcinoma in China involve the HLA class I antigen recognition groove

Nasopharyngeal carcinoma (NPC) is an epithelial malignancy facilitated by Epstein-Barr Virus infection. Here we resolve the major genetic influences for NPC incidence using a genome-wide association study (GWAS), independent cohort replication, and high-resolution molecular HLA class I gene typing including 4,055 study participants from the Guangxi Zhuang Autonomous Region and Guangdong province of southern China. We detect and replicate strong association signals involving SNPs, HLA alleles, and amino acid (aa) variants across the major histocompatibility complex-HLA-A, HLA -B, and HLA -C class I genes (P(HLA-A-aa-site-62) = 7.4 × 10(-29); P (HLA-B-aa-site-116) = 6.5 × 10(-19); P (HLA-C-aa-site-156) = 6.8 × 10(-8) respectively). Over 250 NPC-HLA associated variants within HLA were analyzed in concert to resolve separate and largely independent HLA-A, -B, and -C gene influences. Multivariate logistical regression analysis collapsed significant associations in adjacent genes spanning 500 kb (OR2H1, GABBR1, HLA-F, and HCG9) as proxies for peptide binding motifs carried by HLA- A*11:01. A similar analysis resolved an independent association signal driven by HLA-B*13:01, B*38:02, and B*55:02 alleles together. NPC resistance alleles carrying the strongly associated amino acid variants implicate specific class I peptide recognition motifs in HLA-A and -B peptide binding groove as conferring strong genetic influence on the development of NPC in China.

Why are East Asians more susceptible to several infection-associated cancers (carcinomas of the nasopharynx, stomach, liver, adenocarcinoma of the lung, nasal NK/T-cell lymphomas)?

There are at least five cancers with uniquely high incidence amongst East and Southeast Asian ethnic groups - namely nasopharyngeal carcinoma (NPC); gastric carcinoma; hepatocellular carcinoma (HCC); adeno-carcinoma of the lung in female non-smokers and nasal NK/T-cell lymphomas. They all appear to be related to an infective cause (Epstein Barr Virus, Helicobacter pylori, hepatitis B virus). We hypothesize that a genetic bottleneck 30,000years ago at the Last Glacial Maximum could have resulted in unique genetic polymorphisms in Toll-like receptor 8, making East Asians more vulnerable to these infective associated cancers. This bottleneck could have been caused by the presence of malaria in the southern Himalayan conduit between central and East Asia; and only those with an attenuated innate immune response to the malarial parasite (perhaps reflected by the TLR8 polymorphism) were spared the ravages of cerebral malaria; allowing these people to cross into east Asia, but then rendering them susceptible to later endemic infections and their associated cancers.

Familial and large-scale case-control studies identify genes associated with nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is an epithelial malignancy and has a remarkable geographic distribution, which is highly prevalent in southern China, Southeast Asia, and North Africa. Although most of the NPC are sporadic cases, the familial clustering of NPC has been demonstrated worldwide. Accumulating studies have proposed that the etiology of NPC is multi-stage and multi-factorial, involving genetic lesions, Epstein-Barr virus infection, and environmental exposure. Genetic variations result in differences in gene function, which in turn lead to different susceptibility to disease. Many studies have been carried out to dissect the genetic variants that contribute to NPC susceptibility. This article reviews the current progress of genetic studies to identify genes associated with NPC, focusing on the familial linkage and large-scale case-control study designs.

Non-viral environmental risk factors for nasopharyngeal carcinoma: a systematic review

This review aims to systematically summarize the epidemiological studies on nasopharyngeal carcinoma (NPC) conducted over the past half century, covering descriptive epidemiological studies and reports on non-viral risk factors. Multiple lines of epidemiologic evidence for established risk factors are systematically presented in comprehensive tables. The potential interactions among environmental factors and genetic components, and also the impacts of parallel sequencing technology on the aetiology of NPC are discussed. Finally, we propose a modified model for the pathogenesis of nasopharyngeal carcinoma based on the current knowledge.

Genetic predisposition factors and nasopharyngeal carcinoma risk: a review of epidemiological association studies, 2000-2011: Rosetta Stone for NPC: genetics, viral infection, and other environmental factors

While infection with Epstein-Barr virus (EBV) is known to be an essential risk factor for the development of nasopharyngeal carcinoma (NPC), other co-factors including genetic factors are thought to play an important role. In this review, we summarize association studies conducted over the past decade to evaluate the role of genetic polymorphisms in NPC development. A review of the literature identified close to 100 studies, including 3 genome-wide association studies (GWAS), since 2000 that evaluated genetic polymorphisms and NPC risk in at least 100 NPC cases and 100 controls. Consistent evidence for associations were reported for a handful of genes, including immune-related HLA Class I genes, DNA repair gene RAD51L1, cell cycle control genes MDM2 and TP53, and cell adhesion/migration gene MMP2. However, for most of the genes evaluated, there was no effort to replicate findings and studies were largely modest in size, typically consisting of no more than a few hundred cases and controls. The small size of most studies, and the lack of attempts at replication have limited progress in understanding the genetics of NPC. Moving forward, if we are to advance our understanding of genetic factors involved in the development of NPC, and of the impact of gene-gene and gene-environment interations in the development of this disease, consortial efforts that pool across multiple, well-designed and coordinated efforts will most likely be required.

Momordica Charantia lectin, a type II ribosome inactivating protein, exhibits antitumor activity toward human nasopharyngeal carcinoma cells in vitro and in vivo

The incidence of nasopharyngeal carcinoma (NPC) remains high in endemic regions, including southern China, northern Africa, and North America. One of the promising therapeutic approaches on NPC is drug screening from natural products, such as components from traditional Chinese medicine. In this study, the antitumor activity of Momordica charantia lectin (MCL), a type II ribosome inactivating protein from bitter gourd, on NPC was investigated. MCL evinced potent cytotoxicity toward NPC CNE-1 (IC(50) = 6.9) and CNE-2 (IC(50) = 7.4) cells but minimally affected normal NP 69 cells. Further investigation disclosed that MCL induced apoptosis, DNA fragmentation, G(1)-phase arrest, and mitochondrial injury in both types of NPC cells. The reduction of cyclin D1 and phosphoretinoblastoma (Rb) protein expression contributed to arrest at G(1)-phase of the cell cycle. These events were associated with regulation of mitogen-activated protein kinases (MAPK; including p38 MAPK, JNK, and ERK) phosphorylation and promoted downstream nitric oxide (NO) production. Concurrent administration of the p38 MAPK inhibitor SB-203580 significantly diminished NO production and lethality of MCL toward NPC cells. Further studies revealed that MCL increased cytochrome c release into the cytosol, activated caspases-8, -9, and -3, and enhanced production of cleaved PARP, subsequently leading to DNA fragmentation and apoptosis. Finally, an intraperitoneal injection of MCL (1.0 mg/kg/d) led to an average of 45% remission of NPC xenograft tumors subcutaneously inoculated in nude mice. This is the first article that unveils the potential of a type II RIP, MCL, for prevention and therapy of NPC.

A gender-specific association of CNV at 6p21.3 with NPC susceptibility

Copy number variations (CNVs), a major source of human genetic polymorphism, have been suggested to have an important role in genetic susceptibility to common diseases such as cancer, immune diseases and neurological disorders. Nasopharyngeal carcinoma (NPC) is a multifactorial tumor closely associated with genetic background and with a male preponderance over female (3:1). Previous genome-wide association studies have identified single-nucleotide polymorphisms (SNPs) that are associated with NPC susceptibility. Here, we sought to explore the possible association of CNVs with NPC predisposition. Utilizing genome-wide SNP-based arrays and five CNV-prediction algorithms, we identified eight regions with CNV that were significantly overrepresented in NPC patients compared with healthy controls. These CNVs included six deletions (on chromosomes 3, 6, 7, 8 and 19), and two duplications (on chromosomes 7 and 12). Among them, the CNV located at chromosome 6p21.3, with single-copy deletion of the MICA and HCP5 genes, showed the highest association with NPC. Interestingly, it was more specifically associated with an increased NPC risk among males. This gender-specific association was replicated in an independent case-control sample using a self-established deletion-specific polymerase chain reaction strategy. To the best of our knowledge, this is the first study to explore the role of constitutional CNVs in NPC, using a genome-wide platform. Moreover, we identified eight novel candidate regions with CNV that merit future investigation, and our results suggest that similar to neuroblastoma and prostate cancer, genetic structural variations might contribute to NPC predisposition.

Fluctuations of epstein-barr virus serological antibodies and risk for nasopharyngeal carcinoma: a prospective screening study with a 20-year follow-up

Background

The impact of variation of Epstein-Barr virus (EBV) antibody titers before the development of nasopharyngeal carcinoma (NPC) is still unclear. We analyzed the fluctuations of antibodies against EBV before histopathological diagnosis to assess the risk of NPC and aimed to provide a reliable basis for screening in high risk populations.

Methods

This study was based on a population-based screening program in Sihui County in Guangdong Province of China. A total of 18,986 subjects were recruited in 1987 and 1992, respectively. Baseline and repeated serological tests were performed for IgA antibodies against EBV capsid antigen (VCA/IgA) and early antigen (EA/IgA). Follow-up until the end of 2007 was accomplished through linkage with population and health registers. Cox proportional hazards regression model was used to estimate the relative risk of NPC in association with EBV antibodies. Time-dependent receiver operating characteristic curve (ROC) analysis was used to further evaluate the predictive ability.

Results

A total of 125 NPCs occurred during an average of 16.9 years of follow-up. Using baseline information alone or together with repeated measurements, serological levels of VCA/IgA and EA/IgA were significantly associated with increased risks for NPC, with a striking dose-response relationship and most prominent during the first 5 years of follow-up. Considering the fluctuant types of serological titers observed during the first three tests, relative risk was highest among participants with ascending titers of EBV VCA/IgA antibodies with an adjusted hazard ratio (HR) of 21.3 (95% confidence interval [CI] 7.1 to 64.1), and lowest for those with decreasing titers (HR = 1.5, 95% CI 0.2 to 11.4), during the first 5 years of follow-up. Time-dependent ROC analysis showed that VCA/IgA had better predictive performance for NPC incidence than EA/IgA.

Conclusion

Our study documents that elevated EBV antibodies, particularly with ascending titers, are strongly associated with an increased risk for NPC.