TRANSFORMATION BY EBV LATENT MEMBRANE PROTEIN 1

eb病毒（EBV）潜伏膜蛋白（LMP1）在大多数与eb病毒相关的恶性肿瘤中均有表达，其在淋巴细胞和上皮细胞系中的表达深刻影响其生物学表型和基因表达。LMP1是唯一的EBV基因，可以将永活的啮齿动物成纤维细胞系转化为裸小鼠失去接触抑制，降低血清依赖性，锚定独立性和致瘤性。LMP1与肿瘤坏死因子受体（TNFR）相关因子（TRAFS）相互作用，激活NFkB转录因子和JNK激酶。我们在重链免疫球蛋白启动子/增强子的控制下产生了三个lmp1转基因小鼠系。当LMP1在淋巴瘤组织中高水平表达时，小鼠发生B细胞淋巴瘤的几率增加了5倍。这一结果表明，在不表达其他EBV基因的情况下，LMP1在体内具有致癌作用，并表明LMP1是EBV相关淋巴瘤发展的主要促进因素。我们还表明，LMP1通过TRAF相互作用域诱导表皮生长因子受体（EGFR）的表达，并通过突变TRAF相互作用产生了两个关于EGFR诱导的温度敏感突变体。我们的初步数据表明，LMP1也诱导EGFR在啮齿动物成纤维细胞中的表达。在这项资助中，我们将确定lmp1介导的转化的生化基础，并确定有助于肿瘤发生的细胞基因。我们的具体目标是：1)通过鉴定LMP1与激活的信号通路的分子相互作用来进一步表征转基因淋巴瘤；2)确定转基因小鼠中LMP1的表达是否与核癌基因c-myc的激活协同作用；3)确定肿瘤抑制因子p53的失活是否会增加转基因小鼠中LMP1的恶性潜能。4)通过鉴定LMP1的基本结构域和激活的信号通路来表征LMP1在啮齿动物成纤维细胞中的转化；5)利用EGFR信号传导抑制剂和两种温度敏感的LMP1形式确定LMP1诱导EGFR对啮齿动物成纤维细胞转化的贡献。

The Epstein-Barr virus (EBV) latent membrane protein (LMP1) is expressed in most of the malignancies associated with EBV and its expression in lymphoid and epithelial cell lines profoundly affects their biologic phenotype and gene expression. LMP1 is the only EBV gene that can transform immortalized rodent fibroblast lines to loss of contact inhibition, lower serum dependence, anchorage independence, and tumorigenicity in nude mice. LMP1 interacts with the tumor necrosis factor receptor (TNFR) associated factors (TRAFS) through which it activates the NFkB transcription factor and JNK kinase. We have generated three lineages of LMP 1 transgenic mice with LMP l expressed under the control of the heavy chain immunoglobulin promoter/enhancer. The mice have a 5 fold increase in the development of B cell lymphoma with LMP1 expressed at high levels in the lymphoma tissues. This result indicates that LMP1, without expression of other EBV genes, is oncogenic in vivo and suggests that LMP1 is a major contributing factor to the development of EBV-associated lymphomas. We have also shown that LMP1 induces the expression of epidermal growth factor receptor (EGFR) through the TRAF interacting domain and by mutating the TRAF interacting have produced two temperature sensitive mutants with regard to EGFR induction. Our preliminary data indicates that LMP1 also induces expression of the EGFR in rodent fibroblasts. In this grant, we will determine the biochemical basis of LMP1-mediated transformation and identify cellular genes that contribute to oncogenesis. Our specific aims are to l) further characterize the transgenic lymphomas by identifying the molecular interactions of LMP1 and the activated signaling pathways, 2) determine if LMP1 expression in transgenic mice synergizes with activation of the nuclear oncogene, c-myc, 3) determine if inactivation of the tumor suppressor, p53, increases the malignant potential of LMP1 in transgenic mice, 4) characterize LMP l transformation of rodent fibroblasts by identifying the essential domains of LMP1 and the signaling pathways that are activated, 5) determine the contribution of EGFR induction by LMP1 to rodent fibroblast transformation using inhibitors of EGFR signaling and two temperature sensitive forms of LMP1.