Quantitative Gene Expression in Human Lung Epithelium

描述（由申请人提供）：只有十分之一的吸烟者或戒烟者一生中会患肺癌。肺癌预防和早期发现策略都需要确定一个高风险的烟草吸烟者亚群，并将重点放在强化戒烟、化学预防和早期疾病筛查工作上。确定这一高危亚群是本实验室的长期目标。烟草烟雾的成分包括多芳烃、亚硝胺和芳香胺。因此，可能的候选易感基因可能包括那些在首次接触烟草烟雾的肺上皮细胞中编码参与致癌物初始生物活化和失活的酶的基因，以及那些参与猝灭原位产生的活性氧的基因。这些基因在明确的、暴露于烟雾中的肺上皮中的表达与肺癌风险的关系尚未得到充分研究。我们的一般假设是，通过定量分析，肺癌上皮中致癌物质和抗氧化代谢酶的表达水平将识别肺癌高危吸烟者。随着本实验室对I期和II期致癌物和氧化代谢酶的rna特异性实时定量表达检测的发展，应用于激光显微解剖的人肺上皮，现在可以在感兴趣的靶细胞中量化癌症相关基因的诱导。因此，我们的具体目的是：1)量化激光捕获微解剖、原位暴露的人肺上皮中某些致癌物质代谢酶和抗氧化酶的基因表达和个体间表达差异；2)与烟草烟雾暴露的敏感生物标志物（血浆尼古丁和可替宁）和中间生物标志物(p53-突变频率、谱、3)在多变量模型中，将基因表达和p53数据与肺癌病例和对照状态相关联。因此，我们将定量定义致癌物质和氧化剂代谢基因表达对肺癌的相关易感性，以便将来适应广泛的人群筛查策略。

DESCRIPTION (provided by applicant): Only one in ten current or ex-smokers contracts lung cancer over a lifetime. Lung cancer prevention and early detection strategies all require the identification of a high risk subgroup of tobacco-smokers upon which to focus intensive smoking cessation, chemoprevention and early disease screening efforts. Identifying this high risk subgroup is the long-term objective of this laboratory. Tobacco smoke's composition includes polyaromatic hydrocarbons, nitrosamines, and aromatic amines. Therefore, plausible candidate susceptibility genes may be hypothesized to include those genes encoding enzymes involved in initial carcinogen bioactivation and inactivation, and those involved in quenching in-situ-generated reactive oxygen species, in the lung epithelial cells of first contact with tobacco smoke. Expression of these genes in defined, smoke-exposed lung epithelium has been understudied as it relates to lung cancer risk. Our general hypothesis is that carcinogen and antioxidant metabolizing enzyme expression levels in lung epithelium, by quantitative assays, will identify smokers at high risk for lung cancer. With this laboratory's development of RNA-specific real-time quantitative expression assays for phase I and II carcinogen and oxidant metabolism enzymes, applied to laser microdissected human lung epithelium, it is now feasible to quantify cancer-relevant gene induction in the target cells of interest. Therefore, the specific aims are to 1) Quantify gene expression and interindividual expression differences of selected carcinogen-metabolizing enzymes and antioxidant enzymes in laser capture microdissected, in situ-exposed human lung epithelium, 2) Compare the observed differences with sensitive biomarkers of tobacco smoke exposure (plasma nicotine and cotinine) and an intermediate biomarker (p53- mutation frequency, spectrum, and methylation) and 3) Correlate the gene expression and p53 data with lung cancer case versus control status in multivariate models. We therefore will quantitatively define carcinogen and oxidant metabolizing gene expression - related susceptibility to lung cancer, for future adaptation to broad population screening strategies.