Y-family DNA polymerases and cellular responses to benzo[a]pyrene

描述(由申请人提供)：最近的进展涉及容易出错的DNA聚合酶在高等真核细胞中由环境致癌物诱导的几乎所有突变的产生。这些数据支持了基于选择性调节这些蛋白质的活性的癌症化学预防的前景，其基础是减少突变频率将降低癌症的发病率。然而，使用这些聚合酶中的一种或另一种缺乏的新开发的小鼠模型进行的致癌研究产生了意想不到的结果。具体地说，在突变频率降低的情况下，单个聚合酶的缺乏可能会导致癌症发病率大大增加。这一意想不到的结果与癌症发生的体细胞突变假说不一致，并突显了这样一个事实，即我们对这一聚合酶宇宙的细胞功能的了解存在关键差距。这些研究是在紫外线辐射下进行的，这些酶在化学诱变剂致突变和致癌中的作用在很大程度上仍未被探索。该应用提出了一种假设，即环境致癌物苯并[a]芘(即BPDE)的活化形式在DNA中诱导的过去加合物的诱变跨损伤合成依赖于Y-家族DNA聚合酶ETA和/或IOTA。这将从三个特定的目的进行研究：目的1，确定BPDE在内源性HPRT基因中诱导的突变的频率和频谱，这些突变来自切除修复缺陷小鼠的等基因株，这些小鼠是野生型或组合缺陷的POL、ETA和/或IOTA缺陷的小鼠。目的2，检测聚合酶缺乏对BPDE诱导的细胞周期检查点、细胞凋亡和基因表达的影响。目的3、检测苯并[a]P在同基因聚合酶缺陷小鼠中诱发肺腺瘤/腺癌的发生率和多样性。这项提议将填补我们关于癌症是如何由一种常见的环境致癌物引发的知识的关键空白。这项工作对公众健康的影响是，化学致癌物诱导的突变与癌症的发展有关，特别是肺癌。这项研究的最终目标是了解这些化学物质是如何导致癌症的，以便设计预防疾病的策略。

DESCRIPTION (provided by applicant): Recent advances implicate error-prone DNA polymerases in the generation of virtually all mutations induced by environmental carcinogens in higher eukaryotic cells. These data have supported the promise of cancer chemoprevention based on the selective modulation of the activity of these proteins, based on the assumption that reducing the mutant frequency will reduce the incidence of cancer. However, carcinogenesis studies using newly-developed mouse models in which one or another of these polymerases is deficient have yielded unexpected results. Specifically, deficiency in individual polymerases may result in greatly enhanced cancer incidence in the face of reduced mutation frequencies. This unexpected result is not consistent with the somatic mutation hypothesis of carcinogenesis, and highlights the fact that there are critical gaps in our knowledge of the cellular function of this universe of polymerases. These studies have been done with ultraviolet radiation, and the role of these enzymes in mutagenesis and carcinogenesis by chemical mutagens remains largely unexplored. This application proposes to examine the hypothesis that mutagenic translesion synthesis past adducts induced in DNA by the activated form of the environmental carcinogen benzo[a]pyrene (i.e. BPDE) is dependent on the Y-family DNA polymerases eta and/or iota. This will be examined in three Specific Aims: Aim 1, To determine the frequency and spectrum of mutations induced by BPDE in the endogenous hprt gene of fibroblasts derived from isogenic strains of excision repair-deficient mice that are wild-type or combinatorially deficient in pol, eta, and/or iota. Aim 2, To examine the effect of polymerase deficiency on BPDE-induced cell cycle checkpoints, apoptosis and gene expression in these same cells. Aim 3, To examine the incidence and multiplicity of lung adenomas/adenocarcinomas induced by B[a]P in the isogenic, polymerase-deficient mice. This proposal will fill critical gaps in our knowledge of how cancer is initiated by a common environmental carcinogen. The public health implication of this work is that mutations induced by chemical carcinogens are implicated in the development of cancer, particularly lung cancer. The ultimate goal of this research is to understand how these chemicals cause cancer in order to design strategies to prevent the disease.