Effect of Diesel Exhaust Particles on DNA Deletions

描述（由申请人提供）：自20世纪80年代初以来，暴露于柴油机排气颗粒（DEP）已成为一个严重的环境和职业健康问题，并且有充分的致癌活性证据。事实上，据估计，在南加州，颗粒物的致癌作用中有70%以上来自DEP。加州空气资源委员会估计，暴露70年，每mu/g m-3每百万人中有300个额外癌症的DEP癌症风险。然而，DEP暴露与癌症之间的联系机制目前尚不清楚。遗传不稳定性，特别是DNA缺失参与癌症的病因学。我们表明，在初步的结果，灌胃暴露的小鼠在怀孕期间的DEP造成的DNA缺失的频率增加，在后代使用体内色素沉着测定。我们之前也表明，吸入暴露于香烟烟雾仅4小时，产生的血液尼古丁水平与吸烟者吸烟后的经历相似，诱导后代DNA缺失，表明小鼠试验可用于吸入研究。该试验基于对由pun突变回复引起的被毛和眼睛上的黑点的定量。这种逆转通过缺失p基因内70 kb的内部重复而发生。我们建议在目标1中确定通过吸入妊娠母鼠暴露于DEP的子宫内的后代小鼠是否会出现DNA缺失水平升高，以及可能的DNA加合物和/或氧化性DNA损伤。这些发现可能揭示DEP暴露与癌症之间的潜在联系。此外，研究表明，电离辐射和最近的空气污染显示出延迟的生殖效应，以及先前受辐射的小鼠与未受辐射的小鼠交配后对下一代的影响，即所谓的跨代效应。通过我们的DNA缺失小鼠模型，我们以及其他人已经表明，雄性小鼠暴露于电离辐射会对与未暴露的雌性小鼠交配后的后代产生影响。我们建议在第二个目标，以确定是否暴露的雄性小鼠通过吸入DEP和随后的交配未暴露的雌性小鼠可能会导致在后代的DNA缺失水平的增加。本项目的研究结果可为后续研究建立合适的体内DNA缺失检测方法，并为其他资助机制的拨款申请提供所需的初步结果，以比较不同类型柴油燃料燃烧产物在体内诱导DNA缺失的效力，以及对缺乏氧化DNA损伤修复的转基因小鼠的影响，以及化学预防研究可能抵消任何DEP引起的DNA缺失频率升高，作为基因-环境-营养相互作用。

DESCRIPTION (provided by applicant): Exposure to diesel exhaust particles (DEP) has become a serious environmental and occupational health issue since early 1980s and there is ample evidence of carcinogenic activity. In fact, it is estimated that more than 70 percent of the carcinogenic effects of Particulate Matter in Southern California is derived from DEP. The California Air Resources Board estimates a DEP cancer risk of 300 excess cancers per million people per mu/g m-3 for 70 year exposure. However, the mechanism for the association between DEP exposure and cancer is currently unknown. Genetic instability, in particular DMA deletions are involved in the etiology of cancer. We show in preliminary results that gavage exposure of mice during pregnancy to DEP caused an increased frequency of DMA deletions in the offspring using an in vivo pigmentation assay. We have also previously shown that inhalation exposure to cigarette smoke for only four hours producing a blood nicotine level that is similar to what a smoker experiences after smoking a cigarette induces DNA deletions in the offspring indicating that the mouse assay is useful for inhalation studies. This assay is based on the quantification of black spots on fur and eyes resulting from reversion of the pun mutation. This reversion occurs by deletion of 70 kb of an internal duplication within the p gene. We propose to determine in Aim 1 whether offspring mice exposed in utero via inhalation of the pregnant dams to DEP will develop an elevated level of DNA deletions and possibly DNA adducts and/or oxidative DNA damage. The findings could shed mechanistic light on the potential association between DEP exposure and cancer. In addition, it has been shown that ionizing radiation and more recently air pollution show delayed reproductive effects and effects in the next generation after mating of previously exposed mice to unexposed mice, so called transgenerational effects. With our mouse model for DNA deletions we, as well as others, have shown that exposure of male mice to ionizing radiation causes effects in the offspring after mating with unexposed female mice. We propose to determine in the second aim whether exposure of male mice via inhalation to DEP and subsequent mating to unexposed female mice may result in an increased level of DNA deletions in the offspring. The results obtained in this project could establish the in vivo DNA deletion assay as suitable assay for subsequent studies and provide needed preliminary results for grant applications for other funding mechanisms on the comparison between combustion products of different types of diesel fuels for their in vivo potency to induce DNA deletions and of effects in transgenic mice deficient in oxidative DNA damage repair as well as for chemoprevention studies possibly counteracting any DEP caused elevated frequency of DNA deletions as gene-environment-nutritional interactions.