Epstein-Barr Virus-Enhanced Tumor Progression

描述（由申请方提供）：在与人类癌症病因相关的人类病毒中，爱泼斯坦巴尔病毒（EBV）是不常见的，因为它与多种恶性肿瘤相关，即使只是零星发生。我们的长期目标是了解一个普遍存在的和持久的病毒病原体，通常实现了持久的和谐与其宿主成为致病性多年后，原发性感染。在终身携带状态的背景下，更充分地承认EBV机会主义的新出现的可能性包括病毒再活化，进入更容易感染的细胞和EBV通过预先存在的分子改变增强的恶性进展。在这里，我们研究了EBV肿瘤发生在一个新的概念框架内的机会感染的肿瘤细胞的病毒内源性的主机，与可能的病毒DNA丢失后，一些肿瘤的EBV的增长作出了贡献。目的1将使用激光捕获显微切割和单细胞定量PCR识别的人类肿瘤活检中EBV分布和克隆性的模式，以建立感染、随后的克隆进化和EBV DNA丢失的时间框架。目的2将确定由LMP 2A基因第一个内含子组成的可变重复的EB病毒末端重复（TR）序列如何控制该EB病毒癌蛋白的表达水平。由于TR是肿瘤克隆性的常用病毒标志物，所获得的信息可能涉及细胞选择过程中的TR数量本身，该过程驱动从少数肿瘤细胞的多锥形感染转变为具有最高LMP2A表达的亚组的单克隆生长。目的3将定义EBV冗余和丢失的基因组学。在一个新设计的体外系统的瞬时感染，我们将建立是否EBV过境通过细胞产生表观遗传基因沉默的一个组成部分的多步骤的致癌过程。这项研究的公共卫生相关性在于，它将回答关于EBV与不断扩大的人类肿瘤阵列的不稳定关联的性质的基本生物学问题。EB病毒是否有能力启动每一个肿瘤，它被发现作为目前预设的基础上EB病毒克隆性或它是否有助于疾病的晚期阶段，进入细胞更容易感染和恶性进展之前的分子事故？所获得的信息将进一步阐明EBV在人类癌症中的作用，其预后意义和未来的治疗方法。

DESCRIPTION (provided by applicant): Among human viruses etiologically linked to human cancer, the Epstein Barr virus (EBV) is unusual because of the diverse assortment of malignancies with which it is associated, if only sporadically. Our long term objective is to understand how a ubiquitous and persistent viral pathogen that normally achieves a lasting rapport with its host becomes pathogenic years after primary infection. Emerging possibilities that more fully acknowledge EBV opportunism in the context of the life-long carrier state include viral reactivation with entry into cells made more prone to infection and EBV-enhanced malignant progression by pre-existing molecular alterations. Here, we examine EBV tumorigenesis within a new conceptual framework of chance infection of neoplastic cells by virus endogenous to the host, with possible viral DNA loss from some tumors after EBV contribution to growth has been made. Aim 1 will use the pattern of EBV distribution and clonality in human tumor biopsies, as discerned by laser capture microdissection and single cell quantitative PCR, to establish a time frame for infection, subsequent clonal evolution, and EBV DNA loss. Aim 2 will determine how variably reiterated EBV terminal repeat (TR) sequences, comprising the first intron of the LMP2A gene, govern expression levels of this EBV oncoprotein. With TRs a commonly employed viral marker of tumor clonality, information obtained may implicate TR number per se in a process of cell selection that drives the transition from polyconal infection of a few tumor cells to monoclonal outgrowth of a subset with the highest LMP2A expression. Aim 3 will define the genomics of EBV redundancy and loss. In a newly devised in vitro system of transient infection, we will establish whether EBV transit through a cell produces epigenetic gene silencing as a component of the multistep process of carcinogenesis. The public health relevance of this research is that it will answer fundamental biological questions on the nature of EBV's erratic association with an ever expanding array of human tumors. Does EBV have the capability to initiate every tumor in which it is found as currently presupposed on the basis of EBV clonality or does it contribute instead to late stages of disease, entering cells more prone to infection and malignant progression by prior molecular mishaps? The information gained will further elucidate EBV's role in human cancer, its prognostic significance, and future therapeutic approaches.