Project 2: Oxidative DNA Damage and Genetic Instability In Models Of Intestinal

肠肿瘤发展模型中的氧化 DMA 损伤和遗传不稳定性 众所周知，氧化 DMA 损伤可导致与肿瘤相关的突变 发展。在之前的项目支持期间，我们利用同基因酵母菌株 确定参与去除/修复氧化 DMA 损伤的途径之间的关系 以及那些通过 DNA 聚合酶介导的跨损伤耐受其在基因组中存在的途径 合成和重组导致遗传不稳定。此外，我们已经确定，慢性 未修复的 DNA 损伤的存在会引起“应激适应”反应，从而导致 细胞内活性氧伴随着遗传不稳定性的进一步增加和一系列生理变化 与癌细胞表型相似。在项目2中，我们将进一步定义DNA损伤介导的相关性 ROS/遗传不稳定性反应是小规模和大规模的驱动因素 酵母和哺乳动物细胞中的基因组重排。我们还将确定关系 肿瘤各个阶段的氧化DNA损伤、DNA修复和遗传不稳定性活动之间的关系 小鼠结肠癌系统的发育，其中线粒体和 Nox 介导的 ROS 发生器 已被激活。我们还将继续合作研究，以进一步阐明其中的联系 氧化 mtDNA 损伤、mtDNA 遗传不稳定性和那些做出反应（或未能反应）的系统之间 响应）这样的损害。 该项目的具体目标是利用酵母快速识别关键的 ROS 介体 遗传不稳定性并定义由 ROS 引起的异常染色体变化的性质 外源性和内源性因素引起的 DNA 损伤。酵母研究的结果将被使用 将注意力集中在我们假设在开发过程中存在的类似关系 哺乳动物结肠肿瘤，其中细胞内 ROS 的增加作为驱动因素（通过氧化 DNA 小规模和大规模的基因组变化（从点突变到染色体畸变）， 包括扩增、缺失和非相互易位。这些研究的结果应该 提供了 ROS 在结肠过程中作为遗传不稳定性介质的程度的图片 哺乳动物肠道细胞中的肿瘤发展。

Oxidative DMA Damage and Genetic Instability in Models of Intestinal Tumor Development It is well-established that oxidative DMA damage can cause mutations that have been implicated in tumor development. During the previous program project support period, we exploited isogenic yeast strains to determine the relationships between those pathways involved in removal/repair of oxidative DMA damage and those pathways that tolerate its presence in the genome via DNA polymerase-mediated translesion synthesis and recombination leading to genetic instability. In addition, we have established that the chronic presence of unrepaired DNA damage causes a "stress adaptation" response that leads to an increase in intracellular ROS accompanied by further increases in genetic instability and a host of physiological changes similar to the cancer cell phenotype. In project 2, we will further define the relevance of the DNA damagemediated ROS/genetic instability response within the context of it being a driver of small- and large-scale genomic rearrangements in both yeast and mammalian cells. We will also determine the relationships among oxidative DNA damage, DNA repair and genetic instability activities during various stages of tumor development in a mouse colon cancer system where mitochondrial- and Nox-mediated generators of ROS have been activated. We will also continue our collaborative studies to further elucidate the connections between oxidative mtDNA damage, mtDNA genetic instability and those systems that respond (or fail to respond) to such damage. The specific aims of this project are designed to exploit yeast to rapidly identify key ROS mediators of genetic instability and to define the nature of abnormal chromosomal changes caused by ROS as a result of DNA damage caused by exogenous and endogenous agents. The results of the yeast studies will be used to focus attention on similar relationships that we hypothesize will exist during the development of mammalian colon tumors where increasing intracellular ROS functions as a driver (via oxidative DNA damage) of small- and large-scale genomic changes, from point mutations to chromosomal aberrations, including amplifications, deletions, and non-reciprocal translocations. The results of these studies should provide a picture of the extent to which ROS functions as the mediator of genetic instability during colon tumor development in mammalian intestinal cells.