OXIDIZED DNA BASES AS BIOMARKERS OF TUMOR PROGRESSION

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。早期的致癌理论认为，DNA受到环境因素的破坏，导致DNA密码发生变化。这些变化被称为突变。一旦积累了足够的突变，细胞就不能正常工作，癌症就会出现。吸烟导致肺癌，阳光照射导致皮肤癌的事实支持这一理论。然而，这种直接的环境联系对人类乳腺癌并不明显。最近的一个理论认为，氧的代谢产生自由基，导致致癌的DNA损伤。为了验证后一种理论，有必要测量细胞中自由基损伤的产物。活性氧对细胞造成的损害称为氧化。在一些乳腺癌中，氧化DNA损伤水平的增加与肿瘤进展有关。然而，最常用的DNA氧化标记物，称为8-oxoG，已知是化学不稳定的，并且难以准确测量。重要的是，8-oxoG本身容易氧化形成几种次级氧化产物。 我们建议开发新技术，以检测大鼠和人类乳腺癌细胞中的产物。这种测定可用作进行诊断的基础，用于未来的人类临床和流行病学研究。这些生物标志物的另一个好处是它们最终将应用于动物和人类的化学预防。 AMS是一种理想的技术，由于其灵敏度和鲁棒性作为一种高通量测量方法。相比之下，定量较少的MS方法如FT-MS缺乏AMS用于常规操作的精确度，特别是在每个细胞的几个DNA加合物的预期水平下。这两种技术的组合将允许在阿托摩尔水平或以下的蛋白质多肽的分级分离和检测，这对于小的法医样品是必要的。该项目与AMS RR补助金项目3的目标互补，特别是在使用AMS以进一步了解癌症病因学方面，使用基于DNA的标记。 2006年年度报告的研究重点部分介绍了迄今取得的进展。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. An early theory of carcinogenesis proposes that DNA is damaged by environmental factors, which lead to changes in the DNA code. These changes are called mutations. Once enough mutations accumulate, cells can no longer function properly, and cancer arises. The facts that smoking causes lung cancer, and that sunlight exposure causes skin cancer support this theory. However, such a direct environmental link is not evident for breast cancer in humans. A more recent theory suggests that the metabolism of oxygen produces free radicals that cause carcinogenic DNA damage. In order to validate the latter theory, it is necessary to measure the products of free radical damage in cells. Damage to cells caused by reactive oxygen is called oxidation. In some breast cancers, increased levels of oxidative DNA damage have been associated with tumor progression. However, the most commonly used marker of DNA oxidation, called 8-oxoG, is known to be chemically unstable, and is difficult to measure accurately. Importantly, 8-oxoG is itself easily oxidized to form several secondary oxidation products. We propose to develop new technology that will allow detection of the products in rat and human breast cancer cells. Such an assay can be used as a foundation for making diagnostics for use in future human clinical and epidemiological studies. An additional benefit of these biomarkers will be their eventual application to chemoprevention in animals and humans. AMS is a desirable technique due to its sensitivity and robustness as a method for high-throughput measurement. In comparison, less quantitative MS methods such as FT-MS lack the precision of AMS for routine operations, especially at the expected level of a few DNA adducts per cell. The combination of these two techniques will allow for the fractionation and detection of protein polypeptides at or below attomole levels, which is necessary for small forensic samples. This project is complementary aims to those of Project 3 of the AMS RR grant, particularly with regard to the use of AMS to further understand cancer etiology using DNA-based markers. Progress to date has been presented in the Research Highlights section of the 2006 APR.