Quantitative Gene Expression in Human Lung Epithelium

描述(申请人提供)：只有十分之一的现吸烟者或曾经吸烟者一生中都会患上肺癌。肺癌预防和早期发现战略都需要确定烟草吸烟者的高危亚群，以便重点关注密集戒烟、化学预防和早期疾病筛查工作。识别这一高风险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编码参与致癌物生物激活和失活的酶的基因，以及那些参与猝灭首次接触烟草烟雾的肺上皮细胞中原位产生的活性氧物种的基因。这些基因在明确的吸烟暴露的肺上皮细胞中的表达一直没有得到充分的研究，因为它与肺癌风险有关。我们的一般假设是，通过定量分析，肺上皮细胞中致癌物质和抗氧化剂代谢酶的表达水平将识别出吸烟者患肺癌的高危人群。随着该实验室开发出针对I期和II期致癌物和氧化剂代谢酶的RNA特异性实时定量表达分析，并应用于激光显微解剖的人肺上皮细胞，现在可以对感兴趣的靶细胞中与癌症相关的基因诱导进行量化。因此，本研究的具体目标是：1)量化特定致癌物代谢酶和抗氧化酶在激光捕获显微切割原位暴露的人肺上皮中的基因表达和个体间表达差异；2)将观察到的差异与烟草烟雾暴露的敏感生物标记物(血浆尼古丁和可替宁)和中间生物标记物(P53突变频率、谱和甲基化)进行比较；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，我们将定量定义与肺癌易感性相关的致癌物和氧化剂代谢基因表达，以适应未来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.