Impact of proximal promoter polymorphisms on AHR gene expression in human lung

近端启动子多态性对人肺AHR基因表达的影响

• 批准号: 8698346
• 负责人: DAVID C SPINK
• 金额: $ 6.63万
• 依托单位: WADSWORTH CENTER
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8698346
• 关键词: AHR gene; Affect; Aromatic Polycyclic Hydrocarbons; Aryl Hydrocarbon Receptor; Binding; Binding Sites; Biological Assay; CYP1A1 gene; CYP1B1 gene; Cancer Etiology; Cancer Patient; Carcinogen Metabolism; Carcinogens; Cessation of life; Cytochrome P450; Development; Disease; Electrophoretic Mobility Shift Assay; Enzymes; Epoxy Compounds; Gene Expression; Gene Frequency; Genes; Genetic; Genetic Polymorphism; Genetic Predisposition to Disease; Glutathione S-Transferase; Goals; Heterozygote; Human; In Vitro; Individual; Investigation; Lead; Luciferases; Lung; Lung Neoplasms; Malignant neoplasm of lung; Messenger RNA; Metabolism; Methods; Microsatellite Instability; Mixed Function Oxygenases; Molecular; Normal tissue morphology; Pathway interactions; Phase; Predisposition; Process; Promoter Regions; Proteins; Public Health; Reporter; Risk; Risk Factors; Role; Single Nucleotide Polymorphism; Smoke; Smoker; Specificity; Structure of parenchyma of lung; Transcriptional Regulation; Tumor Cell Line; Tumor Tissue; Variant; carcinogenesis; cigarette smoking; in vitro Assay; insight; novel; promoter; public health relevance; receptor expression; transcription factor

DESCRIPTION (provided by applicant): Since its discovery, the aryl hydrocarbon receptor (AhR) has been recognized as an integral component of the carcinogenic process initiated by smoke-born polycyclic aromatic hydrocarbons and other carcinogens that result from incomplete combustion. The AhR regulates the expression of a group of genes encoding phase I cytochrome P450 monooxygenases, phase II conjugating enzymes, and phase III metabolite transporters that metabolize and dispose of PAH carcinogens, while also causing a limited level of reactive, mutagenic intermediates. Despite the pivotal importance of the AhR in the carcinogenic process in human lung, the underlying molecular mechanisms controlling AhR expression are not well established. Recently, we identified four novel variants of a repeat polymorphism, including two previously unreported single-nucleotide polymorphisms within the repeat, of the human AHR gene and have established a new method for analyzing them. These novel polymorphisms occur in a critical control region of the proximal promoter that contains multiple binding sites for specificity protein transcription factors. Our central hypothesis is tha these newly characterized AHR gene polymorphisms affect the transcriptional regulation of AhR expression, which in turn leads to altered expression and inducibility of the carcinogen-bioactivating enzymes as well as phase II and III pathways of deactivation. The specific aims of our application are: 1) to determine the allelic frequencies of these novel polymorphisms of the AHR gene in normal tissue from lung cancer patients, and 2) to determine the roles of these novel polymorphisms in the transcriptional regulation of AhR expression. We will perform in vitro assays of transcription factor binding and AHR promoter activities in a lung tumor cell line and determine allelic expression of AhR mRNA in normal lung tissue from individuals heterozygous for these polymorphisms. These studies will determine the importance of novel polymorphisms in the AHR gene promoter on AhR expression and may ultimately lead to a clearer understanding of the genetic susceptibility to lung cancer.

描述（由申请人提供）：自发现以来，芳烃受体（AhR）已被认为是由烟雾产生的多环芳烃和不完全燃烧产生的其他致癌物引发的致癌过程的一个组成部分。 AhR 调节一组编码 I 期细胞色素 P450 单加氧酶、II 期结合酶和 III 期代谢物转运蛋白的基因的表达，这些基因代谢和处理 PAH 致癌物，同时还引起有限水平的反应性诱变中间体。尽管 AhR 在人肺致癌过程中至关重要，但控制 AhR 表达的潜在分子机制尚未明确。最近，我们鉴定了人类 AHR 基因重复多态性的四种新变体，包括重复中的两种以前未报道的单核苷酸多态性，并建立了一种分析它们的新方法。这些新的多态性发生在近端启动子的关键控制区域，该区域包含特异性蛋白转录因子的多个结合位点。我们的中心假设是，这些新鉴定的 AHR 基因多态性影响 AhR 表达的转录调控，进而导致致癌生物激活酶的表达和诱导性以及 II 期和 III 期失活途径的改变。我们应用的具体目的是：1）确定肺癌患者正常组织中 AHR 基因的这些新多态性的等位基因频率，2）确定这些新多态性在 AhR 表达转录调节中的作用。我们将在肺肿瘤细胞系中进行转录因子结合和 AHR 启动子活性的体外测定，并确定来自这些多态性杂合个体的正常肺组织中 AhR mRNA 的等位基因表达。这些研究将确定 AHR 基因启动子中的新多态性对 AhR 表达的重要性，并可能最终使人们更清楚地了解肺癌的遗传易感性。