Host pathways regulating Epstein-Barr virus-mediated B cell growth transformation

描述（由研究者提供）：EB病毒是一种致癌性疱疹病毒，与免疫功能低下个体的淋巴瘤相关。体外EBV将原代B细胞转化为无限增殖的淋巴母细胞样细胞系（LCL），转化效率低于10%。虽然几乎所有感染的细胞表达病毒潜伏基因并开始增殖，但在大多数这些细胞中存在对长期增殖的阻断。最近的证据表明，激活的癌基因诱导肿瘤抑制DNA损伤反应（DDR）。在本申请中，我们的目的是了解DDR作为EBV介导的转化的先天抑制因子的作用以及EBV克服这种反应的机制。我们的工作假设是，原发性B细胞感染后的初始EBV潜伏基因表达程序依赖于高水平的EBNA 2活性，其驱动引发宿主DDR的初始过度增殖状态。长期生长依赖于EBNA 3C通过减弱EBNA 2活性和B细胞增殖率来减轻DDR。拟议研究的基本原理是，确定DDR抑制EBV转化的基本效应物，预计将导致EBV相关恶性肿瘤治疗干预的候选靶点。此外，描述病毒蛋白在减轻DDR中的作用将提供对EBV诱导的肿瘤发生机制的深入了解。我们计划通过三个具体目标来测试我们的假设并完成本申请中概述的目标。首先，我们将确定EBV感染后早期检测到的ATM/Chk 2依赖性DDR的关键效应物。其次，我们将确定EBV感染后早期初始细胞分裂过程中EBNA 3C蛋白亚型DDR相关变化的分子基础。第三，我们将确定EBNA 3C在减弱早期感染中EBV诱导的DDR中的遗传要求。这项研究意义重大，因为它旨在确定宿主抑制EBV永生化的关键机制，以及病毒如何克服这种先天肿瘤抑制途径。这方面的知识将有助于确定EBV相关恶性肿瘤的新治疗靶点。例如，一种新的治疗方法可以集中于加强这种肿瘤抑制效应物以阻断EBV驱动的肿瘤的增殖。

DESCRIPTION (provided by investigator): Epstein-Barr virus is an oncogenic herpes virus associated with lymphoma in immune-compromised individuals. In vitro EBV transforms primary B cells into indefinitely proliferating lymphoblastoid cell lines (LCLs) with an efficiency of less than 10%. While nearly all infected cells express viral latent genes and begin to proliferate, a block to long term proliferation exists in the majority of these cells. Recent evidence suggests that activated oncogenes induce a tumor suppressive DNA damage response (DDR). In this application, we aim to understand the role of the DDR as an innate suppressor of EBV-mediated transformation and the mechanisms by which EBV overcomes this response. It is our working hypothesis that the initial EBV latent gene expression program upon primary B cell infection depends on high-level EBNA2 activity, which drives an initial hyper-proliferative state that provokes the host DDR. Long-term outgrowth depends on EBNA3C mitigating the DDR through attenuation of EBNA2 activity and the B cell proliferation rate. The rationale for the proposed research is that determining the essential effectors of the DDR suppressing EBV transformation is expected to lead to candidate targets for therapeutic intervention in EBV-associated malignancies. Further, delineating the role of viral proteins in mitigating the DDR will provide insight into the mechanism of EBV-induced oncogenesis. We plan to test our hypothesis and complete the objectives outlined in this application through three specific aims. First, we will determine the critical effectors of the ATM/Chk2 dependent DDR detected early after EBV infection. Second, we will determine the molecular basis for the DDR-correlated change in EBNA3C protein isoform during early initial cell divisions following EBV infection. Third, we will define the genetic requirements of EBNA3C in attenuating the EBV-induced DDR in early infection. The proposed research is significant because it aims to determine a critical mechanism by which EBV immortalization is suppressed by the host and how the virus overcomes this innate tumor suppressor pathway. This knowledge will be informative towards identifying novel therapeutic targets for EBV-associated malignancy. For example, a novel therapeutic approach could be focused on accentuation of such tumor suppressor effectors to block proliferation of EBV- driven tumors.