JC Virus and Tumor Formation in the Human Colon

描述(由申请人提供)：本申请的假设是JC病毒(JCV)感染人类胃肠道会导致结肠内的慢性潜伏感染。在生命的后期，由于病毒转录控制区(TCR)的重排而发生病毒的重新激活，导致一些结肠上皮细胞表达JCVT抗原。最初，T抗原稳定核β-连环蛋白，从而允许不受调控的增殖，而不会丢失APC基因。T抗原还有其他触发染色体不稳定(CIN)的特性，这是非整倍体肿瘤的标志。在增殖和CIN的背景下，杂合性丢失(LOH)事件发生在关键的肿瘤抑制基因，包括APC和P53。这一应用表明，JCV是基因组不稳定的最初原因，基因组不稳定启动了结肠的多步骤癌变。 我们有数据表明，JCV DNA存在于89%的结肠癌中，以及大多数人的正常结肠组织中。我们发现，来自结肠癌的JCV分离株的TCR中有重排，而正常结肠的TCR中没有重排。这些TCR在体外转录活性更高。我们已经建立了一种新的体外模型，使用的是胎儿结肠细胞系，在该模型中，JCV感染会导致CIN的诱导。我们还通过导入克隆的JCVT抗原在二倍体结肠细胞系中诱导了CIN。 在这一应用中，我们建议通过对大肠肿瘤切除标本的研究，严格检验JCVT抗原的表达与β-连环素的稳定、APC的后期丢失和CIN的启动相关的假设。其次，我们建议使用手术切除的组织和体外方法来确定病毒整合到人类基因组中是否对于T抗原的表达和CIN的诱导是必要的。第三，我们建议使用我们的JCV体外感染模型来研究永生化和转化的时间过程。最后，我们建议检验这一假设，即JCV TCR中的重排提供了一种机制，将潜伏感染转化为活跃感染，导致病毒基因的表达。这项工作的含义是，JCV普遍存在于大多数健康人的胃肠道，可能参与了CIN和结肠癌的发生。如果这种病毒在人类致癌过程中发挥机械作用，这可能导致新的预防和治疗策略。

DESCRIPTION (provided by applicant): The hypothesis of this application is that infection of the human gastrointestinal tract by JC virus (JCV) leads to a chronic, latent infection in the colon. Later in life, reactivation of the virus occurs due to a rearrangement in the transcription control region (TCR) of the virus, which leads to expression of the JCV T-antigen in some colonic epithelial cells. Initially, the T-antigen stabilizes nuclear beta-catenin, which permits unregulated proliferation, without loss of the APC gene. T-antigen has other properties that trigger chromosomal instability (CIN), which is the hallmark of aneuploid tumors. In the setting of proliferation and CIN, loss of heterozygosity ('LOH') events occurs at critical tumor suppressor genes, including APC and p53. This application suggests that JCV is the initial cause of the genomic instability that initiates multi-step carcinogenesis in the colon. We have data that JCV DNA is present in 89% of colon cancers, and in the normal colonic tissues of most people. We have found that there are rearrangements in the TCRs of JCV isolates from colon cancers that are not present in TCRs from the normal colon. These TCRs are more transcriptionally active in vitro. We have developed a novel in vitro model using a fetal colonic cell line in which infection by JCV leads to the induction of CIN. We have also induced CIN in a diploid colonic cell line by transfection of the cloned JCV T-antigen. In this application, we propose to rigorously test the hypothesis that the expression of JCV T-antigen correlates with the stabilization of beta-catenin, the later loss of APC, and the initiation of CIN by studying resected specimens of colorectal neoplasia. Second, we propose to determine whether the integration of the virus into the human genome is necessary for expression of T-antigen and the induction of CIN, using both surgically resected tissues and in vitro approaches. Third, we propose to use our in vitro models of JCV infection to study the time course of immortalization and transformation. Finally, we propose to test the hypothesis that rearrangements in the TCR of JCV provide a mechanism whereby a latent infection is converted into an active one, leading to expression of the viral genes. The implication of this work is that JCV, which is commonly present in the gastrointestinal tract of the majority of healthy humans, may be involved in the initiation of CIN, and colon cancer. If this virus plays a mechanistic role in human carcinogenesis, this could lead to novel preventive and treatment strategies.