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，柴油机尾气颗粒（DEP）暴露已成为一个严重的环境和职业健康问题，有充分的证据表明其致癌活性。事实上，据估计，南加州超过70%的颗粒物致癌效应来自于DEP。加州空气资源委员会估计，在70年的暴露中，每百万人中有300多例患DEP癌症的风险。然而，DEP暴露与癌症之间的关联机制目前尚不清楚。遗传不稳定，特别是DMA缺失与癌症的病因有关。我们在初步结果中表明，在怀孕期间灌胃暴露于DEP的小鼠使用体内色素沉着试验导致后代DMA缺失的频率增加。我们之前的研究也表明，吸入香烟烟雾仅4小时就会产生血液尼古丁水平，与吸烟者吸完烟后的水平相似，从而导致后代的DNA缺失，这表明小鼠试验对吸入研究很有用。这种分析是基于定量的黑点在皮毛和眼睛产生的双关突变的逆转。这种逆转是通过p基因内部重复的70kb的缺失而发生的。我们建议在Aim 1中确定在子宫内通过吸入妊娠鼠暴露于DEP的后代小鼠是否会产生更高水平的DNA缺失和可能的DNA加合物和/或氧化性DNA损伤。这一发现可能会揭示暴露于DEP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生殖效应，并在先前暴露的小鼠与未暴露的小鼠交配后对下一代产生影响，即所谓的跨代效应。通过我们的小鼠DNA缺失模型，我们和其他人已经证明，雄性小鼠在与未暴露的雌性小鼠交配后，暴露在电离辐射下会对后代产生影响。在第二个目标中，我们提出确定雄性小鼠通过吸入DEP暴露并随后与未暴露的雌性小鼠交配是否会导致后代DNA缺失水平增加。本项目获得的结果可以建立体内DNA缺失试验作为后续研究的合适试验，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的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，以及可能抵消任何DEP引起的化学预防研究基因-环境-营养相互作用导致DNA缺失频率升高。

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.