EB病毒诱导的胸腺恶性T细胞淋巴瘤细胞体外长期培养研究

建立含有EB病毒的T细胞淋巴瘤细胞系,为探讨EB病毒的致瘤机理,研究EB病毒在T细胞淋巴瘤发生过程中的作用提供手段.在TPA协同EB病毒诱导胸腺恶性T细胞淋巴瘤动物模型的基础上,联合应用IL-2,将诱导的肿瘤组织进行体外细胞培养,成功地分离获得一株在体外长期存活的淋巴细胞TET.T细胞亚群分类实验证实TET细胞为CD4阳性的T淋巴细胞,PCR和原位杂交可检测到EB病毒的EBERs、LMP1和BARF1,并有LMP1蛋白的表达.TET细胞的获得,有望在体外建立转化细胞系,为体外研究EB病毒的致瘤机理及防治提供理想的实验材料.     

EB病毒BNLF—1基因研究的新进展

EB病毒广泛存在于人群中,它的潜伏感染与鼻咽癌的发生密切相关。EBV在潜伏感染的过程中表达一种潜伏膜蛋白1（LMP1）,具有致瘤性,因此编码LMP1的基因BNLF－1被认为是EBV的瘤基因。BNLF－1基因具有广泛的生物学功能,在鼻咽癌的发生发展过程中起重要作用。近年的研究表明,鼻咽癌来源的EBV与标准株EBV比较存在相当的变异,而鼻咽癌来源的LMP1在致瘤性上也明显强于标准株LMP1。本文将综述BNLF－1基因生物学功能研究方面的新进展,并简要介绍变异型LMP1研究的新成果。     

肠道非何杰金淋巴瘤与EB病毒感染的相关性研究

目的：研究肠道非何杰金淋巴瘤(NHL)与EB病毒(EBV)感染相关性。方法：利用EBV寡核探针(EBER)原位杂交法检测EB病毒。结果：16例肠道NHL好发部位于小肠下端和结肠,以单发瘤结节多见,常伴有溃疡形成。经免疫组化证实3例为T细胞淋巴瘤(18．75％),13例为B细胞淋巴瘤(81．25％)。：EBV—EBER原位杂交3例有阳性表达,均为T细胞淋巴瘤,阳性细胞占肿瘤细胞的25％～75％。B细胞淋巴瘤未见阳性表达。结论：肠道非何杰金淋巴瘤以B细胞淋巴瘤多发,并以惰性淋巴瘤为多见;而T细胞淋巴瘤多为侵袭性,且与EBV感染的相关性较高,与B细胞淋巴瘤无相关性。     

EB病毒诱发人B细胞淋巴瘤的分子病理特性

EB病毒 (EBV ,Epstein Barrvirus)与人类多种肿瘤有关 ,尤其是与鼻咽癌和淋巴瘤的关系密切。为此研究了EB病毒在huPBL SCID嵌合体小鼠体内诱发人B细胞淋巴瘤的分子特性及肿瘤发生机制。从健康成人外周血分离出淋巴细胞 ,将之移植到SCID小鼠腹腔内 ,实验感染EBV ,观察肿瘤的形成 ;采用单向免疫扩散法连续监测小鼠血清中人IgG的含量。分别用PCR方法检测肿瘤组织中是否存在人Alu序列 ,原位杂交检测肿瘤组织中EB病毒小RNA分子EBER 1;免疫组织化学方法检测人白细胞分化抗原 (CD4 5、CD2 0、CD4 5RO、CD3) ,病毒基因(LMP1、EBNA2、BZLF1)的表达 ,以及细胞瘤基因蛋白 (p5 3、C myc、Bcl 2、Bax)在诱发肿瘤中的表达情况。结果发现 ,实验中 34只感染EBV的huPBL SCID小鼠有 2 4只诱发出肿瘤 ,根据病理形态学特征、Alu PCR和免疫标志均证实诱发瘤是人源性B淋巴细胞肿瘤。原位分子杂交显示肿瘤细胞核内存在EBER 1,少数瘤细胞表达EB病毒BZLF1蛋白阳性 ,部分瘤细胞表达LMP1和EBNA2蛋白阳性。连续监测 12只huPBL SCID小鼠血清中人IgG含量 ,发现IgG水平随诱瘤时间延长和肿瘤生长有逐渐增高趋势。免疫组化显示诱发的 2 4例淋巴瘤组织p5 3、C myc、Bcl 2和Bax蛋白表达阳性率分别为 83.33%、10 0 %、95 .83%、91.6 7%。结果     

EB病毒潜伏膜蛋白2A在小鼠B细胞淋巴瘤模型中增强Myc诱导的细胞周期进程

<正>myc基因表达升高是许多人类癌症的共同特性。Epstein-Barr病毒(EBV)与淋巴系统恶性肿瘤有关,但在淋巴瘤中Myc与EB病毒之间的相互作用尚不清楚。EBV潜伏膜蛋白2A(LMP2A)可充当B细胞受体(BCR)的类似物,给受感染的B细胞提供存活信号。与单独表达人myc基因的小鼠(λ-myc小鼠)相比,共表达myc和LMP2A的小鼠(LMP2A/λ-myc小鼠)能加速B细胞淋巴瘤的发生。该研究发现LMP2A的一个新作用,即通过Myc促进细胞周期G1-S转换,且以蛋白酶体依赖的方式下调细胞周期蛋白依赖激酶     

EB病毒编码的潜伏膜蛋白与泛素蛋白酶系统

EB病毒(Epstein-Barr virus,EBV)是人类疱疹病毒,与淋巴系统、上皮细胞肿瘤相关。其编码潜伏性膜蛋白(LMPl、LMP2A和LMP2B)特别是LMP1,由于它是众多EBV编码蛋白质中唯一被明确证明能恶性转化原代B细胞、鼠成纤维细胞和人上皮细胞的蛋白质,所以被列为癌基因。最近对潜伏膜蛋白的研究显示．潜伏膜蛋白与病毒利用泛素蛋白酶系统来达到逃避宿主免疫应答等机制有关,研究这个过程也许可以开发新的策略来防治EBV相关肿瘤。     

EB 病毒LMP1 在肿瘤研究中的进展

EB病毒(Epstein-Barr virus,EBV)是具有致瘤潜能的疱疹病毒,与多种恶性肿瘤的发生相关。EB病毒编码的潜伏性膜蛋白1(Latent membrane protein-1,LMP1)作为其主要的致瘤蛋白,能通过细胞内多种信号传导通路,调节和控制细胞的生长、增殖、分化、迁移与凋亡,从而在癌变的发生和发展过程中发挥重要的作用。本文主要就LMP1的结构、生物学功能、介导的信号通路及其与肿瘤关系的相关进展做一阐述。     

EB病毒及其癌基因LMP1对上皮细胞的转化作用

EB病毒(EBV)是一种人群感染率较高的致病性疱疹病毒,与伯基特氏淋巴瘤、鼻咽癌的关系最为明确。近年来EBV在上皮源性肿瘤发生、发展中的作用受到众多学的关注,而其癌基因LMP1在上皮源性肿瘤发病的病因学方面的作用更成为研究的热点。本综述就EBV进入上皮细胞、永生化上皮细胞的机制、LMP1的基本结构及其对上皮细胞的生物学功能作一较为详细的阐述。     

EB病毒编码的潜伏膜蛋白1参与鼻咽癌恶性演进的转录调控实验研究

探讨EB病毒潜伏膜蛋白1(LMP1)激活激活蛋白1(AP1),和核转录因子(NF-κB)在鼻咽癌细胞SUNE-1及亚细胞株恶性演进中的作用.运用报告基因法和凝胶电泳迁移率法(EMSA)分析AP1和NF-κB反式激活活性和DNA结合活性,蛋白质印迹检测蛋白质表达;裸鼠致瘤实验结合组织制片研究瘤细胞的成瘤和转移能力. 结果显示恶性程度不同的SUNE-1亚细胞株的反式激活活性、DNA结合活性、LMP1蛋白表达及c-Jun氨基端激酶(JNK)活性均存在明显差异,且与细胞恶性程度正相关.这些结果提示LMP1活化AP1和NF-κB的信号通路参与了鼻咽癌细胞SUNE-1的恶性演进过程.     

EB病毒即刻早期BRLF1基因在淋巴瘤组织中多态性研究

目的：EB病毒（Epstein．Barrvirus,EBV）感染宿主细胞包括潜伏期和裂解期,它的即刻早期基因BRLFl编码产物Rta蛋白是EBV从潜伏期到裂解期的关键性调节因子。目前,Rta蛋白已成为治疗EBV相关肿瘤的靶蛋白,但有关BRLFl基因在EBV阳性淋巴瘤中的研究甚少,本研究旨在明确EB病毒即刻早期基因BRLFl在EB病毒阳性淋巴瘤组织中的变异规律,探讨其变异意义。方法：原位杂交筛选EB病毒阳性淋巴瘤（BL）,提取EB病毒DNA。PCR结合DNA测序检测EBV阳性淋巴瘤中BRLFl基因多态性,应用DNAStar软件对序列进行对比分析。结果：共筛选出27例EBV阳性淋巴瘤标本,在27例BL阳性标本中成功扩增BRLFl基因,与B95—8标准序列比对分析,共发现20处无义突变和19处有义突变。8例属于BR1-A亚型,18例属于BRl—C亚型,1例属于BRl-E亚型,其中以BRl-A亚型和BRl-C亚型最为常见,分别为29．6％（8／27）、66．7％（18／27）。与EBVaGC、NPC和1W相比,4种人群BRLFl亚型的分布不同,其中BRl-A亚型更多出现在健康人群中,BRl-C亚型更多出现在NPC和BL中。在Rta蛋白功能区中,二聚体区域呈高度保守,在DNA结合区域和反式激活区域均检测出序列突变,16种CTL抗原表位中,只有NAA、QKE和ERP表位发生改变,且NAA和QKE在健康人群中突变率较高。结论：山东地区EB病毒阳性淋巴瘤BRLFl基因变异类型主要为BRl-A亚型和BRl-C亚型。BRl-C亚型可能与BL相关,发生在Rta蛋白DNA结合区域和反式激活区域的突变可能对其功能产生影响,多数CTL表位序列保守提示BRLFl可以用作EBV相关淋巴瘤免疫治疗的靶基因。     

Epstein-Barr virus-encoded latent membrane protein 1 (LMP1) and LMP2A function cooperatively to promote carcinoma development in a mouse carcinogenesis model

The Epstein-Barr virus (EBV) proteins latent membrane proteins 1 and 2 (LMP1 and LMP2) are frequently expressed in EBV-associated lymphoid and epithelial cancers and have complex effects on cell signaling and growth. The effects of these proteins on epithelial cell growth were assessed in vivo using transgenic mice driven by the keratin 14 promoter (K14). The development of papillomas and carcinomas was determined in the tumor initiator and promoter model using dimethyl benzanthracene (DMBA), followed by repeated treatments of 12-O-tetradecanoyl phorbol 13-acetate (TPA). In these assays, LMP1 functioned as a weak tumor promoter and increased papilloma formation. In contrast, mice expressing LMP2A did not induce or promote papilloma formation. Transgenic LMP1 mice had slightly increased development of squamous cell carcinoma; however, the development of carcinoma was significantly increased in the doubly transgenic mice expressing both LMP1 and LMP2A. DMBA treatment induces an activating mutation in the Harvey-ras (H-ras(61)) oncogene, and this mutation was identified in most papillomas and carcinomas although several papillomas and carcinomas in K14-LMP1 and K14-LMP1/LMP2A mice lacked the mutation. Analysis of signaling pathways that are known to be activated by LMP1 and/or LMP2 indicated that all genotypes had high levels of activated extracellular signal-regulated kinase (ERK) and Stat3 in carcinomas with significantly higher activation in the doubly transgenic carcinomas. These findings suggest that, in combination, LMP1 and LMP2 contribute to carcinoma progression and that this may reflect the combined effects of the proteins on activation of multiple signaling pathways. This study is the first to characterize the effects of LMP2 on tumor initiation and promotion and to identify an effect of the combined expression of LMP1 and LMP2 on the increase of carcinoma development.     

An Epstein-Barr Virus (EBV) mutant with enhanced BZLF1 expression causes lymphomas with abortive lytic EBV infection in a humanized mouse model

Immunosuppressed patients are at risk for developing Epstein-Barr Virus (EBV)-positive lymphomas that express the major EBV oncoprotein, LMP1. Although increasing evidence suggests that a small number of lytically infected cells may promote EBV-positive lymphomas, the impact of enhanced lytic gene expression on the ability of EBV to induce lymphomas is unclear. Here we have used immune-deficient mice, engrafted with human fetal hematopoietic stem cells and thymus and liver tissue, to compare lymphoma formation following infection with wild-type (WT) EBV versus infection with a "superlytic" (SL) mutant with enhanced BZLF1 (Z) expression. The same proportions (2/6) of the WT and SL virus-infected animals developed B-cell lymphomas by day 60 postinfection; the remainder of the animals had persistent tumor-free viral latency. In contrast, all WT and SL virus-infected animals treated with the OKT3 anti-CD3 antibody (which inhibits T-cell function) developed lymphomas by day 29. Lymphomas in OKT3-treated animals (in contrast to lymphomas in the untreated animals) contained many LMP1-expressing cells. The SL virus-infected lymphomas in both OKT3-treated and untreated animals contained many more Z-expressing cells (up to 30%) than the WT virus-infected lymphomas, but did not express late viral proteins and thus had an abortive lytic form of EBV infection. LMP1 and BMRF1 (an early lytic viral protein) were never coexpressed in the same cell, suggesting that LMP1 expression is incompatible with lytic viral reactivation. These results show that the SL mutant induces an "abortive" lytic infection in humanized mice that is compatible with continued cell growth and at least partially resistant to T-cell killing.     

Interferon production potentials of various human lymphoblastoid cell lines

A number of human lymphoblastoid cells were examined concerning their ability to produce spontaneously liberated and virus-induced interferon (IFN). It was found that, in addition to B cells, various T and nonT-nonB lymphoblastoid cells responded well to Sendai virus infection to form IFN, the characterization of which has been recently reported (20). One B lymphoblastoid cell line from an infectious mononucleosis (IM) patient produced a large amount of IFN-alpha and might become an alternative source of IFN production. Among 68 cell lines examined, 35 cell lines liberated 10 U/ml or more of IFN spontaneously in culture fluid. The presence of Epstein-Barr virus (EBV) genome or its activation appears to have no correlation with the spontaneous liberation of IFN. Spontaneously produced IFN from three cell lines was characterized as IFN-alpha. Comparatively higher amounts of IFN were produced in cells from IM patients than those from Burkitt's lymphoma cases or healthy adults. Spontaneously produced IFN was detected more easily in cells transformed by EBV alone than in those transformed by EBV and a tumor promoter, TPA.     

金属硫蛋白 - 潜伏膜蛋白融合基因的体外转录调控

ＥＢ病毒（ＥＢＶ）是一种与地区性伯基特氏淋巴瘤、鼻咽癌、何杰金氏病等多种人体肿瘤有关的疱疹病毒．已往的研究表明,潜伏膜蛋白（ＬＭＰ）基因是ＥＢＶ最可能的致瘤基因．为制备ＬＭＰ基因转基因小鼠,探讨ＬＭＰ的体内致瘤作用,首先构建了含鼠金属硫蛋白－１（ＭＴ－１）基因调控区和ＬＭＰ基因编码区的ｐＢＲ３２２－ＭＴ－ＬＭＰ质粒,并用电击法将该质粒与ｐＫＪ１－Ｎｅｏ质粒共转染人胃癌细胞株ＭＧＣ,对ＭＴ－ＬＭＰ基因在转染细胞中的整合、转录情况及重金属镉和镍对该融合基因的转录调控进行了研究．结果表明：（１）两质粒共转染效率为８６．７％;（２）ＰＣＲ和Ｓｏｕｔｈｅｒｎ杂交分析显示,完整的ＭＴ－ＬＭＰ基因已整合入转染的ＭＧＣ细胞基因组,且在不同的转染细胞克隆中,ＭＴ－ＬＭＰ基因整合的方式及拷贝数不同,拷贝数从１到１９不等;（３）ＲＴ－ＰＣＲ和Ｎｏｒｔｈｅｒｎ杂交分析证实,ＭＴ－ＬＭＰ基因不仅在转染的ＭＧＣ中能够转录,而且在１０μｍｏｌ／Ｌ镉诱导下,ＭＴ－ＬＭＰ基因转录增强,平均增高约１．４倍．结果说明,在ＭＴ－１基因调控区指导下,ＬＭＰ基因不但有ｍＲＮＡ水平的表达,而且其表达受重金属镉的调控,上述结果为制备ＭＴ－ＬＭＰ转基因小鼠     

Effects of thymus grafts in nude mice transplated with human malignant tumors

The effect of neonatal thymus grafts implanted in nude mice previously transplanted with three different human malignant tumors - an adenocarcinoma of the colon, a malignant melanoma and a Burkitt's lymphoma - were studied. In all immunologically reconstituted animals tumord were rejected. Tumor rejection stated 2-3 weeks after thymus implantation, and was completed after 30-6 weeks. Histological examination of lymphoid tissues showed a correlation between immunological reconstitution and tumor rejection. The rejection process showed a characteristic histologic picture with 3 phases - an early, an intermediate and a late phase - these were similar in the three tumor types examined. The possible mechanisms of reconstitution and tumor rejection are discussed.     

Immune surveillance and therapy of lymphomas driven by Epstein-Barr virus protein LMP1 in a mouse model

B cells infected by Epstein-Barr virus (EBV), a transforming virus endemic in humans, are rapidly cleared by the immune system, but some cells harboring the virus persist for life. Under conditions of immunosuppression, EBV can spread from these cells and cause life-threatening pathologies. We have generated mice expressing the transforming EBV latent membrane protein 1 (LMP1), mimicking a constitutively active CD40 coreceptor, specifically in B cells. Like human EBV-infected cells, LMP1+ B cells were efficiently eliminated by T cells, and breaking immune surveillance resulted in rapid, fatal lymphoproliferation and lymphomagenesis. The lymphoma cells expressed ligands for a natural killer (NK) cell receptor, NKG2D, and could be targeted by an NKG2D-Fc fusion protein. These experiments indicate a central role for LMP1 in the surveillance and transformation of EBV-infected B cells in vivo, establish a preclinical model for B cell lymphomagenesis in immunosuppressed patients, and validate a new therapeutic approach.     

Latent Membrane Protein LMP2A Impairs Recognition of EBV-Infected Cells by CD8+ T Cells

The common pathogen Epstein-Barr virus (EBV) transforms normal human B cells and can cause cancer. Latent membrane protein 2A (LMP2A) of EBV supports activation and proliferation of infected B cells and is expressed in many types of EBV-associated cancer. It is not clear how latent EBV infection and cancer escape elimination by host immunity, and it is unknown whether LMP2A can influence the interaction of EBV-infected cells with the immune system. We infected primary B cells with EBV deleted for LMP2A, and established lymphoblastoid cell lines (LCLs). We found that CD8+ T cell clones showed higher reactivity against LMP2A-deficient LCLs compared to LCLs infected with complete EBV. We identified several potential mediators of this immunomodulatory effect. In the absence of LMP2A, expression of some EBV latent antigens was elevated, and cell surface expression of MHC class I was marginally increased. LMP2A-deficient LCLs produced lower amounts of IL-10, although this did not directly affect CD8+ T cell recognition. Deletion of LMP2A led to several changes in the cell surface immunophenotype of LCLs. Specifically, the agonistic NKG2D ligands MICA and ULBP4 were increased. Blocking experiments showed that NKG2D activation contributed to LCL recognition by CD8+ T cell clones. Our results demonstrate that LMP2A reduces the reactivity of CD8+ T cells against EBV-infected cells, and we identify several relevant mechanisms.     

Nasopharyngeal carcinoma-associated Epstein-Barr virus-encoded oncogene latent membrane protein 1 potentiates regulatory T-cell function

Sequence variation in the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) oncogene structure may affect antigen-presenting cell (APC) function of infected B cells and immune escape by EBV-specific T cells and thus contribute to the development of malignancy. Normal B cell-associated LMP1 (B-LMP1) upregulates B cell APC function through activation of the necrosis factor (NF)-kappaB subunit, RelB. We examined the ability of B-LMP1 and a nasopharyngeal carcinoma-associated LMP1 (NPC-LMP1) to modulate B cell APC function and T-cell responses. B lymphoma cells transfected with NPC-LMP1 stimulated resting T cells in mixed lymphocyte reaction less efficiently than B-LMP1 transfectants. Unexpectedly, antigen presentation to CD4(+) T helper cells was reduced owing to potentiation of regulatory T-cell function by NPC-LMP1 transfectants, which produce increased levels of interleukin-10, rendering CD4(+) T cells hyporesponsive. Thus, after primary EBV infection, T cells may escape activation by NPC-LMP1. These observations have important implications for the establishment of EBV-associated malignancy in the context of infection with tumour-associated EBV LMP1 variants.