Noninvasive diagnosis of nasopharyngeal carcinoma: nasopharyngeal brushings reveal high Epstein-Barr virus DNA load and carcinoma-specific viral BARF1 mRNA

Nasopharyngeal carcinoma (NPC) is the most prevalent ENT-tumour in Indonesia. We investigated the primary diagnostic value of Epstein-Barr virus (EBV) DNA load and mRNA detection in noninvasive nasopharyngeal (NP) brushings, obtained prospectively from consecutive Indonesian ENT-patients with suspected NPC (N=106) and controls. A subsequent routine NP biopsy was taken for pathological examination and EBER-RISH, yielding 85 confirmed NPC and 21 non-NPC tumour patients. EBV DNA and human DNA load were quantified by real-time PCR. NP brushings from NPC patients contained extremely high EBV DNA loads compared to the 88 non-NPC controls (p<0.0001). Using mean EBV DNA load in controls plus 3 SD as cut-off value, specificity, sensitivity, positive and negative predictive values were 98, 90, 97 and 91%, respectively. Epstein-Barr nuclear antigen 1 (EBNA1) and the carcinoma-specific BARF1 mRNA were detected by nucleic acid sequence based amplification and found in 86 and 74% of NP brushings, confirming NPC tumour cell presence. EBV RNA positivity was even higher in fresh samples stored at -80 degrees C until RNA expression analyses (88% for both EBNA1 and BARF1). EBV RNA-negative NP brushings from proven NPC cases had the lowest EBV DNA loads, indicating erroneous sampling. No EBV mRNA was detected in NP brushings from healthy donors and non-NPC patients. In conclusion, EBV DNA load measurement combined with detection of BARF1 mRNA in simple NP brushings allows noninvasive NPC diagnosis. It reflects carcinoma-specific EBV involvement at the anatomical site of tumour development and reduces the need for invasive biopsies. This procedure may be useful for confirmatory diagnosis in large serological NPC screening programs and has potential as prognostic tool.     

Expression of Epstein-Barr virus-encoded proteins in nasopharyngeal carcinoma

Expression of the Epstein-Barr virus (EBV) encoded nuclear antigens (EBNA 1 to 6) and membrane-associated protein (LMP) was investigated by immunoblotting in 83 nasopharyngeal carcinoma (NPC) biopsies and 25 other tumor and normal tissue specimens from the head and neck region. Fifty-eight of the 83 NPC biopsies were large enough to yield parallel data on virus DNA and viral expression. All 16 cases of clinically diagnosed and histologically confirmed NPCs from North Africa contained EBV DNA and expressed EBNA-1. Of 31 clinically diagnosed NPCs from China, 29 contained EBV DNA and 25 of these expressed EBNA-1. One control tissue biopsy from the oropharynx of NPC patients contained EBV DNA, but none expressed EBNA-1. The latent membrane protein (LMP) was detected in 22/31 of the Chinese and in 10/16 of the North African NPC biopsies. None of the NPC biopsies or control tissues expressed detectable amounts of EBNA 2 or any of the other 4 nuclear antigens which are invariably expressed in EBV-transformed B cells. A smaller number of tumors from Malaysia and East Africa exhibited a similar pattern of expression. EBV was rescued from a nude-mouse-passaged North African NPC tumor by co-cultivation of the tumor cells with umbilical cord blood lymphocytes. The tumor expressed EBNA 1 and LMP, but not EBNA 2 or the other 4 EBNAs. The resulting LCLs expressed all 6 nuclear antigens, EBNA 1 to 6 and LMP. Our data suggest that expression of the EBV genome is regulated in a tissue-specific fashion.     

EBV 抗体和EBV-DNA 在鼻咽癌诊断及分期的研究*

目的：评估EBNA1/IgA 、Zta/IgA 、VCA/IgA 和EBV-DNA对不同分期鼻咽癌的诊断效能,探讨各指标阳性率与鼻咽癌分期的关系。方法：收集2010年3 月至2015年9 月中山大学附属中山医院收治的初诊鼻咽癌患者152 例,健康体检者675 例。采用酶联免疫吸附法（ELISA）检测血清EBNA1/IgA 、Zta/IgA 和VCA/IgA 抗体ROD 值,荧光定量PCR （fluorescence quantitative PCR,FQ-PCR ）检测血浆EBV-DNA水平。比较单独和联合应用EBV 标记物对各期鼻咽癌的诊断效能,同时分析各指标阳性率与鼻咽癌分期的关系。结果：鼻咽癌患者EBNA1/IgA 、Zta/IgA 、VCA/IgA 和EBV-DNA阳性率显著高于健康体检者（P < 0.01）。 EBNA1/IgA 在早期鼻咽癌表达相对较高,灵敏度为77.8% ,而EBV-DNA在晚期鼻咽癌的灵敏度最高为88.8% ,两者特异度均在96% 以上。联合检测中EBNA1/IgA 并联EBV-DNA检测的灵敏度为92.1%（早期为82.5% 、晚期为98.9%）,特异度为96.9% 。EBV-DNA阳性率与鼻咽癌临床分期和N 分期呈正相关,Zta/IgA 阳性率与N 分期呈正相关（P < 0.01）。 结论：在无症状人群中进行鼻咽癌筛查,单项指标首选EBNA1/IgA 。晚期患者的辅助诊断则推荐EBV-DNA。两者并联检测可进一步提高鼻咽癌诊断效能。EBV-DNA是鼻咽癌分期和病情监测的重要指标,Zta/IgA 可间接反映淋巴结转移情况,有望对患者病情评估起到参考作用。     

EB病毒相关胃癌组织中病毒基因的表达

背景与目的：EB病毒(Epstein—Barr virus,EBV)与多种恶性肿瘤的发生有关,在鼻咽癌及淋巴瘤等组织中EBV的存在形式和表达已有报道,研究表明不同肿瘤组织中EBV的存在形式和表达不同,在胃癌组织中EBV某些基因尤其是裂解性基因的表达情况报道较少。为明确胃癌组织中EBV潜伏性基因和裂解性基因的表达情况,本研究从mRNA水平检测胃癌组织中EBV潜伏感染和裂解感染相关基因的表达,从分子水平探讨EBV编码基因与胃癌发生发展的关系。方法：应用PCR—Southern杂交检测185例胃癌及其相应癌旁组织中特异性EBVDNA片段,进一步用原位杂交(ISH)技术检测PCR阳性标本EBV编码小RNA1(EBERl)的表达,癌细胞EBERl阳性者确定为EBV相关胃癌(EBV—associated gastric carcinoma,EBVaGC)。采用RT-PCR和Southern杂交技术检测EBVaGCs组织中EBV核抗原(EBNAs)基因转录启动子(Qp、Cp和Wp)、潜伏性基因(EBNA1、EBNA2基因,潜伏膜蛋白LMP1、LMP2A和LMP2B基因)和裂解性基因(即刻早期基因BZLF1和BRLF1,早期基因BARF1和BHRF1,晚期基因BcLF1和BLLF1)的表达。结果：185例胃癌标本EBV阳性率为7．03％(13／185),癌旁组织均为阴性。13例EBVaGCs组织中均检测到启动子Qp mRNA,而Wp和Cp mRNA则为阴性。潜伏性基因中EBNA1 mRNA均阳性(13／13),而EBNA2、LMP1和LMP2B均未见表达,5例标本(5／13)检测到LMP2A mRNA。裂解性基因中BcLF1有7例(7／13)表达阳性,2例(2／13)BHRF1表达阳性,6例标本(6／13)检测到BZLF1 mRNA,BARF1亦有6例(6／13)表达阳性,而BRLF1和BLLF1mRNA均为阴性。结论：EBVaGC中EBV潜伏类型为Ⅰ型或介于Ⅰ和Ⅱ型之间的独特类型;EBVaGC组织中部分裂解性基因表达阳性,部分胃癌存在BARF1和BHRF1表达,其在胃癌中所起的作用有待进一步研究。     

鼻咽癌组织中EBV潜伏膜蛋白2跨膜区CTL表位序列分析

背景与目的：Epstein-Barr病毒在华南地区鼻咽癌细胞中表达核抗原1（EBNA1）、潜伏膜蛋白1（LMP1）和潜伏膜蛋白2（LMP2）等病毒蛋白质。LMP2 mRNA不仅几乎100％表达于鼻咽肿瘤细胞,而且LMP2蛋白还具有较强的免疫原性,是一个较理想的免疫治疗靶点。本研究分析广州地区来源鼻咽癌组织的LMP2基因跨膜区的CTL表位序列,为设计以LMP2抗原为靶点的鼻咽癌免疫治疗提供依据。方法：收集广州地区鼻咽癌患者鼻咽活检组织20例和正常鼻咽粘膜活检组织3例,提取DNA,半巢式PCR扩增LMP2基因跨膜区．直接测序．分析CTL表位序列。结果：与标准株B95．8相比．鼻咽癌和正常鼻咽粘膜活检组织来源的LMP2基因跨膜区存在14处碱基替换,形成6处氨基酸替换．导致4处CTL表位序列变异（SSC、TYG、CLG和VMS）,其中VMS多态性为初次报道。由于从鼻咽癌组织扩增的LMP2序列与从正常鼻咽粘膜扩增的LMP2序列相同,表明这些变化是地域相关的病毒多态性而非鼻咽癌相关的病毒变异。结论：广州地区来源的Epstein-Barr病毒LMP2基因存在多态性．产生4处CTL表位序列变化。在设计以LMP2为靶点的免疫治疗时,应充分考虑病毒基因多态性的影响。     

The significance of LMP1 expression in nasopharyngeal carcinoma

The Epstein-Barr virus (EBV)-encoded latent membrane protein 1 (LMP1) is a key effector of EBV-mediated B cell transformation. LMP1 displays potent oncogenic properties in rodent fibroblasts, and induces a wide range of effects in B cells and epithelial cells. LMP1 functions as a constitutively active tumor necrosis factor receptor (TNFR) engaging a multitude of signaling pathways that include NF-kappaB, the mitogen-activated protein kinases (MAPKs), JNK, p38, the JAK/STAT pathway and, more recently, the small Rho GTPases. The constitutive activation of these signaling cascades explains LMP1's ability to induce such a diverse array of morphological and phenotypic effects in cells and provides an insight into how LMP1 may induce cell transformation. The frequent expression of LMP1 in undifferentiated nasopharyngeal carcinoma (NPC) points to a role for this viral oncoprotein as a key effector molecule in NPC pathogenesis.     

鼻咽癌中EB病毒LMP1基因N端Xho I酶切位点的丢失

背景与目的：众所周知,EB病毒LMP1基因在鼻咽癌变过程起着一定的作用。本研究通过检测广东地区鼻咽癌组织EB病毒LMP1基因N-末端区Xho I酶切位点的丢失,探讨LMP1基因变异在鼻咽癌发生发展中的作用。方法：收集中山大学肿瘤防治中心鼻咽癌患者鼻咽新鲜活检标本63例。收集EB病毒健康携带者外周血单个核细胞(PBMCs)10例作为对照。采用QIAamp DNA Mini Kit和QIAamp DNA Blood Mini Kit分别抽取组织和外周血单个核细胞的DNA,应用巢式PCR扩增EB病毒LMP1基因的N-末端区,并用Xho I对扩增产物进行酶切。采用四色荧光末端终止法对扩增产物进行序列分析。结果：10例健康携带者外周血单个核细胞的EB病毒LMP1基因N-末端区均未见Xho I酶切位点的丢失。63例鼻咽癌组织中有50例(79．37％)出现Xho I酶切位点的丢失(Xho I—loss),还有4例(6．34％,)为Xho I酶切位点部分丢失,只有9例(14．29％)未见Xho I酶切位点的丢失(wt-Xho I)。除了Xho I酶切位点的丢失(nt：169423～169428;GAGCTC→GA□TCTC)外,还发现四个错义点突变。结论：本研究所检测的广东地区EB病毒健康携带者外周血单个核细胞所携带的：EB病毒LMP1基因为wt—Xho I,而在鼻咽癌组织中主要为Xho I-loss。因此,我们认为EB病毒LMP1基因N-末端区Xho I酶切位点的丢失和其他的错义点突变可能是在鼻咽癌的发生发展过程中产生的。     

EB病毒与鼻咽癌相关性的研究进展

Epstein-Barr病毒（EBV）的潜伏感染与鼻咽癌（Nasopharyngeal carcinoma,NPC）密切相关,在感染人体后长期潜伏,可表达多种基因,其潜伏膜蛋白（LMP）编码基因、EB病毒核抗原（EBNA）基因及EBV编码的小RNA（EBER）可以通过不同的机制致鼻咽癌。本文就EBV与NPC的关系,与NPC相关的EBV的生物学特性和进展作一综述。     

Expression of the Epstein-Barr virus genome in a nasopharyngeal carcinoma epithelial tumor cell line

An epithelial tumor cell line was recently established from a biopsy specimen of a nasopharyngeal carcinoma (NPC), and designated HONE-I. Uncloned (parental) HONE-I and HONE-I clone (C)-40 cells were found to contain latent Epstein-Barr virus (EBV). Expression of the latent EBV genome in HONE-I C-40 cells has been examined. It was possible to detect a small percentage of cells spontaneously synthesizing EBV early antigen (EA) and virus capsid antigen (VCA) by immunofluorescence (IF). In addition, the EBV nuclear antigens (EBNA-I and EBNA-2), as well as the EBV latent membrane protein (LMP) were detected in the HONE-I cells. Attempts were made to induce the latent EBV genome in these cells with iododeoxyuridine (IUdR). We observed a significant increase in the number of EA/VCA-positive cells, an increase in EBV DNA, the synthesis of virus particles, and the rescue of infectious virus after treatment of HONE-I C-40 cells with IUdR. The HONE-I C-40 cells should facilitate studies of the expression and regulation of the EBV genome in NPC epithelial tumor cells, which have not previously been available.     

Genome-wide expression profiling reveals EBV-associated inhibition of MHC class I expression in nasopharyngeal carcinoma

To identify the molecular mechanisms by which EBV-associated epithelial cancers are maintained, we measured the expression of essentially all human genes and all latent EBV genes in a collection of 31 laser-captured, microdissected nasopharyngeal carcinoma (NPC) tissue samples and 10 normal nasopharyngeal tissues. Global gene expression profiles clearly distinguished tumors from normal healthy epithelium. Expression levels of six viral genes (EBNA1, EBNA2, EBNA3A, EBNA3B, LMP1, and LMP2A) were correlated among themselves and strongly inversely correlated with the expression of a large subset of host genes. Among the human genes whose inhibition was most strongly correlated with increased EBV gene expression were multiple MHC class I HLA genes involved in regulating immune response via antigen presentation. The association between EBV gene expression and inhibition of MHC class I HLA expression implies that antigen display is either directly inhibited by EBV, facilitating immune evasion by tumor cells, and/or that tumor cells with inhibited presentation are selected for their ability to sustain higher levels of EBV to take maximum advantage of EBV oncogene-mediated tumor-promoting actions. Our data clearly reflect such tumor promotion, showing that deregulation of key proteins involved in apoptosis (BCL2-related protein A1 and Fas apoptotic inhibitory molecule), cell cycle checkpoints (AKIP, SCYL1, and NIN), and metastasis (matrix metalloproteinase 1) is closely correlated with the levels of EBV gene expression in NPC.     

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。     

鼻咽癌诊断和治疗的分子生物学新进展

鼻咽癌（nasopharyngeal carcinoma，NPC）是一种与EB病毒（Epstein-Barr virus，EBV）的感染密切相关的恶性肿瘤。在我国南方及东南亚地区患病率特别高，但几十年来，EBV参与和导致肿瘤发生的机制仍不清楚。最近的鼻咽癌基因组分析将其定义为遗传上均一性的癌症，认为主要是由NF-κB 负调控因子的突变或由于EBV潜伏膜蛋白1（latent membrane protein 1,LMP1）的过表达引起的，成为了鼻咽癌基因组学的标志。来自EBV阳性鼻咽癌模型的RNA测序数据也凸显了PI3K信号通路的异常表达在鼻咽癌中的重要性，并可以预判患者的预后。NF-κB信号通路的靶向治疗目前仍是一个挑战，应该探索更多创新药物的发现方法去针对鼻咽癌所特有的非典型NF-κB信号通路。我们对鼻咽癌的进一步研究应集中在鉴定复发性和转移性鼻咽癌的组学情况，开发基于基因的药物以及使用新开发的EBV阳性鼻咽癌模型进行大规模药物的筛选，找到有临床应用潜力的靶向药物，以进一步提高鼻咽癌患者的生存率。     

鼻咽癌前期病变中的EB病毒感染

背景与目的：鼻咽癌中的浸润性癌细胞均感染了EB病毒（Epstein-Barr virus．EBV）。前期病变可见于早期鼻咽癌癌旁上皮。本研究旨在通过检测前期病变中的EB病毒,探讨EB病毒感染存鼻咽癌变过程中的作用,及其基因型在鼻咽癌变过程中发生的宿主内演变。方法：采用核酸原位杂交检测15例早期鼻咽癌活检组织中的EB病毒编码RNA（EBV—encoded RNA,EBER）。采用巢式PCR法检测前期病变和癌巢中的EB病毒类型和潜伏膜蛋白1（latent membrane protein 1,LMPI）EB病毒株。具有代表性的LMPI基因羧基末端PCR产物采用四色荧光终止序列技术进行DNA序列分析。结果：所有15例早期鼻咽癌中的绝大多数浸润性癌细胞均呈EBER阳性。在15例的期病变中．14例可检测到EBER阳性的异常上皮细胞和／或浸润性淋巴细胞。单个A型EB病毒可在9例癌巢（11例适用）及9例前期病变（10例通用）的DNA样本中检测到。EB病毒LMP1基因羧基末端在15例癌巢DNA样本中均可检测到,其中14例是30bp缺失型LMP1 EB病毒株,1例是野生型和30bp缺失型LMP1株的混合感染。在11例适合做EB病毒LMP1基因羧基末端扩增的前期病变的DNA样本中,5例呈野生型和30bp缺失型LMP1 EB病毒株的混合感染,4例是单个缺大型LMP1 EB病毒株感染,1例呈单个野生型LMP1 EB病毒株感染,1例呈阴性反应。野生型LMP1基因羧基末端的DNA序列与B95—8细胞的DNA序列完全一致;30bp缺大型LMP1基因羧基末端的DNA序列却其有30bp缺失（密码子：346～355）和4个错义点突变（密码子：334、335、338和366）。结论：鼻咽上皮细胞的EB病毒感染是癌变过程中侵袭前的事件;而在鼻咽癌变过程中,EB病毒基因型会产生宿主内的演变。     

Elevated expression of ICAM1 (CD54) and minimal expression of LFA3 (CD58) in Epstein-Barr-virus-positive nasopharyngeal carcinoma cells.

Undifferentiated nasopharyngeal carcinoma (NPC) is a remarkable entity among human tumors because of its constant association with the Epstein-Barr virus (EBV). Malignant epithelial cells harbor the EBV genome and often express at least 2 species of latent EBV protein (EBNA1 and LMP1). Despite the massive presence of tumor-infiltrating lymphocytes, NPC cells obviously escape immune surveillance directed to EBV antigens. Previous investigations carried out on EBV-positive Burkitt lymphoma (BL) cells have shown that this fact may be partially accounted for by a lack of expression of ICAM1 (CD54) and LFA3 (CD58). ICAM1 and LFA3 have therefore been investigated in fresh NPC biopsies and transplanted NPCs. With only 1 exception out of 9 cases, NPC cells appear to express high levels of ICAM1 and low levels of LFA3. This is a complete inversion of the pattern observed in normal epithelial cells in vivo. Additional investigations will be required to determine to what extent these characteristics affect T-cell interactions with NPC cells, specially in the process of EBV-antigen recognition.