Multiparametric Detection of Antibodies against Different EBV Antigens to Predict Risk for Nasopharyngeal Carcinoma in a High-Risk Population of China

A novel causal model for nasopharyngeal carcinoma

The development of nasopharyngeal carcinoma (NPC) and its unique geographic distribution have long been attributed to a combination of dietary intake of salt-preserved fish, inherited susceptibility, and early-life infection with the Epstein-Barr virus (EBV). New findings from our large, rigorously designed, population-based case-control study of NPC in southern China have enabled substantial revision of this causal model. Here, we briefly summarize these results and provide an updated model of the etiology of NPC. Our new research identifies two EBV genetic variants that may be causally involved in the majority of NPC in southern China, and suggests the rise of modern environmental co-factors accompanying cultural and economic transformation in NPC-endemic regions. These discoveries can be translated directly into clinical and public health advances, including improvement of indoor air quality and oral health, development of an EBV vaccine, enhanced screening strategies, and improved risk prediction. Greater understanding of the roles of environmental, genetic, and viral risk factors can reveal the extent to which these agents act independently or jointly on NPC development. The history of NPC research demonstrates how epidemiology can shed light on the interplay of genes, environment, and infections in carcinogenesis, and how this knowledge can be harnessed for cancer prevention and control.

Application of magnetic immunofluorescence assay based on microfluidic technology to detection of Epstein-Barr virus

EB病毒(Epstein-Barr virus, EBV)的早期诊断能够降低患者发生重大疾病的风险。临床上常用的EBV抗体的检测方法存在耗时长、试剂消耗大和效率低等缺点。相比于传统的检测方法,微流控(microfluidics)技术具有高通量、试剂消耗少,污染少和自动化程度高等优点,磁免疫荧光技术具有检测效率高、信号强等优点,将两者的优势结合,能够弥补传统方法的不足。鉴于此,采用聚甲基丙烯酸甲酯(PMMA)作为芯片原材料,经过激光切割及真空热压加工工艺能够快速获得芯片。将包被抗原的磁珠及包被抗人抗体的荧光微球经过冷冻干燥工艺快速冻干成小球并嵌入芯片内,经过孵育和清洗后,进行检测。通过图像分析快速得到检测结果。通过精密度、特异性、剂量-反应曲线及检出限测试,进行性能验证。通过与化学发光免疫分析法(CLIA)检测的临床样本比对,进行方法学与临床应用评价。结果显示相对标准偏差(RSD)均小于10%。与多种常见的病原体抗体均无交叉反应。EB病毒衣壳抗原(Epstein-Barr viral capsid antigen, EB VCA)IgG项目的检出限为1.92 U/mL,线性范围为1.92~200 U/mL,阳性符合率为95.77%(68/71),阴性符合率为86%(43/50); EB VCA IgA项目的检出限为2.79 U/mL,线性范围为2.79~200 U/mL,阳性符合率为92%(46/50),阴性符合率为92.96%(66/71); EB病毒核心抗原1(Epstein-Barr nuclear antigen 1, EB NA1)IgG项目的检出限为3.13 U/mL,线性范围为3.13~200 U/mL,阳性符合率为92.96%(66/71),阴性符合率为92%(46/50); EB NA1 IgA项目的检出限为1.53 U/mL,线性范围为1.53~200 U/mL,阳性符合率为90%(45/50),阴性符合率为91.55%(65/71)。4个项目能在20 min内快速完成检测,且与临床上使用CLIA方法测试的结果具有良好的相关性,可以为临床提供一种快速、灵敏、简便、自动化程度高和易于基层推广的检测方法。

RSPO2 silence inhibits tumorigenesis of nasopharyngeal carcinoma by ZNRF3/Hedgehog-Gli1 signal pathway

R-spondins 2 (RSPO2) protein is a member of RSPO family which plays an essential role in stem cell survival, development and tumorigenicity. There has several evidence suggested that RSPO2 involved in breast, gastric, liver and colorectal cancer. However, the specific function and mechanism of RSPO2 in nasopharyngeal carcinoma (NPC) remain unknown. In the present study, we first observed that RSPO2 expression was elevated in NPC cell lines SUNE-6-10B, SUNE-5-8F, and CNE-1 compared with the normal laryngeal epithelia cell line NP69. Knockdown of RSPO2 significantly inhibits SUNE-6-10B and CNE-1 cell survival and proliferation by using CCK-8 assay and Edu assay, respectively. Further studies verified that RSPO2 silence suppressed migration and invasion of SUNE-6-10B and CNE-1 cells. Further studies suggested that RSPO2 silence suppressed epithelial-to-mesenchymal transition (EMT) related protein E-cadherin expression and promoted Vimentin and N-cadherin expression both in SUNE-6-10B and CNE-1 cells. Molecular mechanism explorations showed that RSPO2 deletion increased ZNRF3 expression and inhibited Gli1 expression. Additionally, knockdown ZNRF3 expression or overexpression Gli1 both reversed the effects of RSPO2 silence on NPC growth and metastasis. Finally, RSPO2 depletion was impaired NPC tumor growth in vivo animal experiments. In conclusion, the present study confirmed that RSPO2 silence inhibits the tumorigenesis of NPC via ZNRF3/Hedgehog-Gli1 signal pathway.

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.

A Randomized Controlled Trial on Evaluation of Plasma Epstein-Barr Virus Biomarker for Early Diagnosis in Patients With Nasopharyngeal Carcinoma

INTRODUCTION

Early diagnosis of nasopharyngeal carcinoma (NPC) remains a major problem in Southern China. Epstein-Barr virus (EBV) biomarkers have been widely used in NPC screening. This study aims to evaluate the early diagnostic performances of individual EBV biomarkers in NPC.

METHODS

The levels of EBV biomarkers-IgA antibodies against EBV nuclear antigen 1 (EBNA1-IgA), EBV capsid antigen (VCA-IgA), EBV early antigen (EA-IgA), EBV BZLF1 transcription activator protein (Zta-IgA) and IgG antibodies against EBV BRLF1 transcription activator protein (Rta-IgG)-from 106 NPC patients (stage I and II) and 150 normal subjects were measured. VCA-IgA and EA-IgA were detected by immunofluorescence assay (IFA), EBNA1-IgA, Rta-IgG and Zta-IgA were measure by enzyme-linked immunosorbent assay (ELISA), and EBV DNA was detected by qPCR. Statistical analyses of a single index were conducted to evaluate the significance of NPC early diagnosis and TNM classification.

RESULTS

The level of EBNA1-IgA, EBV DNA, VCA-IgA, EA-IgA, Rta-IgG and Zta-IgA in early-stage NPC was significantly higher than in healthy controls (all P < 0.001). EBNA1-IgA yielded the biggest area under the curve (AUC) of 0.962 in distinguishing early-stage NPC patients from the normal subjects, with a sensitivity of 91.5% and a specificity of 98.7%. However, EBV biomarker levels were not associated with tumor size (all P > 0.050), whereas four biomarker levels (EBNA1-IgA, EBV DNA, VCA-IgA, EA-IgA) were related to lymph node metastasis (N0 and N1-2), among which EBNA1-IgA and EBV DNA showed good performance. Finally, high correlation was found between VCA-IgA and EA-IgA (r > 0.800).

CONCLUSION

A single EBNA1-IgA exhibits excellent discrimination performance in early diagnosis of NPC and could become a promising marker for NPC screening.

Accuracy Evaluation and Comparison of 14 Diagnostic Markers for Nasopharyngeal Carcinoma: A Meta-Analysis

The aim of the present study was to collect published studies and compare the diagnostic accuracy of different markers for nasopharyngeal carcinoma (NPC). We systematically searched PubMed/MEDLINE, EMBASE, Cochrane Library, CNKI, and Wanfang for relevant studies until April 29, 2020. The revised Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool was used to evaluate the methodological quality of the studies. The sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the curve (AUC) values of the diagnostic markers were combined by a bivariate mixed effect model to compare their diagnostic accuracy. We explored heterogeneity through meta-regression. In total, 244 records from 101 articles were included, with 49,432 total study subjects (13,109 cases and 36,323 controls). EA-IgG, Zta-IgG, and Epstein-Barr virus (EBV) DNA load in non-invasive nasopharyngeal brushings (EBV-DNA brushings) have both high sensitivity and specificity, EBNA1-IgG and VCA-IgG have only high sensitivity, and EBNA1-IgA, VCA-IgA, Rta-IgG, Zta-IgA, HSP70, and serum sialic acid (SA) have only high specificity. The bivariate mixed effect model of EA-IgA had a significant threshold effect. Meta-regression analysis showed that ethnicity affected EBNA1-IgA, EBNA1-IgG, VCA-IgA, and EBV DNA load in plasma, test methods affected EBNA1-IgG, publication year affected VCA-IgA, and sample size affected Rta-IgG. There was significant publication bias for VCA-IgA and Rta-IgG (P < 0.05). EA-IgG, Zta-IgG, and EBV-DNA brushings are good diagnostic markers for NPC. The diagnostic accuracy was influenced by publication year, sample size, test methods, and ethnicity.

Preliminary evaluation of a candidate international reference for Epstein-Barr virus capsid antigen immunoglobulin A in China

BACKGROUND

The detection of the Epstein-Barr capsid antigen (VCA) immunoglobulin A (IgA) is widely used in the diagnosis of nasopharyngeal carcinoma (NPC), but a reference standard for evaluating the presence of VCA-IgA is not yet available. Therefore, a reference standard is urgently needed for a uniform and quantitative detection of VCA-IgA.

METHODS

A mixed reference serum from three NPC patients diluted with healthy subject serum was made as a potential first international standard for VCA-IgA. VCA-IgA was detected in twenty NPC patients by four ELISA kits and two chemiluminescent immunoassays kits using the reference as a calibration curve. The performance of these six kits was evaluated, and the quantitative results were compared.

RESULTS

Our results showed a good linearity of the reference in different kits. Without reference, the difference of the total coefficient of variation (from 3.98 to 43.11%) and Within-run coefficient of variation (from 2.47 to 19.66%) was large in the 6 kits. The positive and negative coincidence rate between the 6 kits and indirect immunofluorescence for NPC diagnosis was 75% overall agreement, but a difference among the six kits was found, ranging from 55 to 90%. The concentration of VCA-IgA in the 20 NPC samples led in the division into three categories such as negative, low, or medium/high positive, but these concentrations were significantly different within these three categories depending on the kit used of the 6 considered. However,a good correlation (R² = 0.986) was observed between Antu and Beier ELISA kits.

CONCLUSIONS

The reference serum mightbe used as a reference standard for a better comparison of the results from different kits/laboratories. However, the quantitative results of some kits are still inconsistent due to the diversity of VCA antigens.

Identification of candidate genes of nasopharyngeal carcinoma by bioinformatical analysis

OBJECTIVE

This study aimed to identify candidate genes as potential biomarkers in nasopharyngeal carcinoma (NPC) by bioinformatical analysis.

METHODS

Three microarray datasets: GSE32906, GSE15170, GSE53819 were download from public database and analyzed to identify the differentially expressed genes (DEGs) between NPC and normal samples. Functional and pathway enrichment analysis of the DEGs were performed. Protein-protein interaction network and gene-transcription factor regulatory network of DEGs were constructed. And the expression of hub genes in NPC was also validated based on the public database.

RESULTS

A total of 16 up-regulated and 27 down-regulated genes were screened out from the microarray datasets. Functional and pathway enrichment analysis showed that DEGs were mostly enriched in positive regulation of angiogenesis, mesenchymal cell proliferation, cell surface and DNA binding, ECM-receptor interaction pathway, PI3K-Akt signaling pathway, and pathways in cancer. Five hub genes JUN, VEGFA, FOXM1, MYB, and WNT5A were identified from the protein-protein interaction network. Subsequently, the hub gene-transcription factor regulatory network revealed that STAT3, MYC, SOX2, RUNX2 present key relations with hub genes. The expression of these five hub genes were also validated to be differentially expressed among NPC and normal samples.

CONCLUSIONS

The current study indicated that the hub DEGs JUN, VEGFA, FOXM1, MYB, and WNT5A we identified might be potential therapeutic biomarkers of NPC.

Intermittent abortive reactivation of Epstein-Barr virus during the progression of nasopharyngeal cancer as indicated by elevated antibody levels

The development of nasopharyngeal carcinoma (NPC), a common cancer in Southeastern Asia, is closely associated with Epstein-Barr virus (EBV) infection; however, the aetiological role of EBV in NPC pathogenesis remains enigmatic. The life cycle of EBV in NPC patients is defined as latency II, while the antibodies specific to lytic phase proteins, as well as lytic genes, were highly expressed in NPC patients. The correlation between antibody levels and the progression of NPC has been reported in some studies; however, most of these studies focused on IgA antibodies, and the results in different articles were not consistent. In this study, we concurrently determined the levels of IgA and IgG antibodies specific to six purified recombinant EBV antigens associated with different replication statuses of EBV: EBNA1 associated with latency II; the non-structural antigens Zta, TK, EA-D and EA-R associated with immediate-early and early lytic phases; and the EBV matrix protein VCA p18, which is involved in late lytic phase. Levels of antibodies specific to immediate-early and early antigens were correlated with the tumour progression, especially tumour size. The levels of antibodies specific to some lytic phase antigens were also correlated with lymph node inclusion and metastasis. However, the antibody specific to the latency II antigen EBNA1 was not correlated with either tumour size or metastasis. Consistent with previous transcriptome studies, the results suggested both the expression of lytic phase genes at the protein level and the intermittent reactivation of EBV in NPC patients.

Recent advances in the management of nasopharyngeal carcinoma

Over the last few years, certain areas in the management nasopharyngeal carcinoma (NPC) that have an impact on the care of these patients have evolved, particularly with regard to liquid biopsies, minimally invasive surgery, and advances in chemotherapy and immunotherapy. Beyond its proven role in the diagnostics, surveillance, and treatment of NPC, liquid biopsy with plasma Epstein–Barr virus DNA in the screening of high-risk populations for NPC is strongly supported by recent evidence. Surgery of the nasopharynx is reserved for locally recurrent NPC, and in recent years there have been great strides in minimally invasive techniques with survival rates similar to those of open techniques in treating NPC. Induction chemotherapy in a recent pooled analysis was shown to be superior to concurrent chemotherapy alone for locoregionally advanced NPC. Finally, immunotherapy with a PD-1 inhibitor in NPC has been shown to have 1-year overall survival rates comparable to those of other patients with heavily pre-treated metastatic or recurrent NPC. In this commentary, we discuss these recent advances and their potential in the clinical management of patients with NPC.