Molecular mechanism of cytochrome P4501A1 expression.

细胞色素P4501A1表达的分子机制。

• 批准号: 8288709
• 负责人: BHAGAVATULA MOORTHY
• 金额: $ 35.39万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-01 至 2016-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8288709
• 关键词: A549; Aromatic Polycyclic Hydrocarbons; Benzo(a)pyrene; CYP1A1 gene; CYP1A2 gene; Cancer Etiology; Carcinogens; Cells; Charcoal; Chemoprevention; Chromatin Remodeling Factor; Cytochrome P-450 CYP1A1; Cytochrome P450; Cytochromes; DNA; DNA Adduction; DNA Adducts; Development; Diesel Exhaust; Dose; Drug Regulations; Enzymes; Event; Gene Expression; Genes; Genetic Transcription; Hepatic; Human; In Vitro; Knockout Mice; Lead; Ligation; Liver; Lung; Malignant neoplasm of lung; Meat; Mediating; Methods; Molecular; Mus; Mutation Spectra; Nucleic Acid Regulatory Sequences; Particulate Matter; Plasmids; Play; Polymerase Chain Reaction; Prevention strategy; Regulation; Response Elements; Role; Specificity; Surgical incisions; Testing; Transcriptional Activation; Transgenic Organisms; Tumor Pathology; Wild Type Mouse; Withdrawal; adduct; attenuation; carcinogenesis; chemotherapy; cigarette smoking; environmental chemical; exposed human population; in vivo; lung carcinogenesis; lung tumorigenesis; novel; nuclease; overexpression; promoter; receptor; receptor expression; tumorigenesis; tumorigenic

DESCRIPTION (provided by applicant): Polycyclic aromatic hydrocarbons (PAHs) are present in cigarette smoke, particulate matter, and in charcoal broiled meats. The cytochrome P450 (CYP)1A enzymes play pivotal roles in the activation of PAHs to metabolites that are interact covalently with DNA, a critical event in the initiation of carcinogenesis. The central hypothesis of this application is that CYP1A1 and CYP1A2 enzymes play reciprocal roles in PAH-mediated carcinogenesis, and that a CYP1A2-dependent MC metabolite(s) contributes to the formation of sequence- specific DNA adducts on the regulatory regions of the CYP1A1 promoter [e.g., AHR response elements (AHREs)], leading to a novel mechanism by which MC-DNA adduct(s) will suppress CYP1A1 gene expression. The following Specific Aims are proposed. 1. To determine the mechanistic role of CYP1A1 and 1A2 enzymes in PAH-mediated lung cancers. This aim has two sub-aims: (i) To test the hypothesis that mice lacking the gene for Cyp1a2 will be more susceptible, and those lacking the gene for Cyp1a1 will be less susceptible to PAH-induced lung carcinogenesis and tumorigenesis than similarly exposed WT mice. (ii) To test the hypothesis that humanized CYP1A1 mice will be more susceptible to lung carcinogenesis and tumorigenesis than WT mice, while humanized CYP1A2 mice will be less susceptible. 2. To determine the molecular mechanisms of sustained induction and suppression of hepatic and pulmonary CYP1A1 by MC in vivo. This aim has two sub-aims: (i) To test the hypothesis that hepatic CYP1A2 mechanistically contributes to the suppression of sustained hepatic and pulmonary CYP1A1 by MC. (ii) To test the hypothesis that MC elicits persistent human CYP1A1 induction by sustained transcriptional activation of the corresponding promoter, and that hepatic CYP1A2 will suppress persistent induction of hepatic and pulmonary CYP1A1 expression in transgenic humanized mice expressing the human CYP1A1 (hCYP1A1-luc or hCYP1A1-GFP) on Cyp1a1- or Cyp1a1/1a2-null backgrounds. 3. To determine the molecular mechanisms of suppression of pulmonary CYP1A1 induction. We will test the hypothesis that CYP1A2-derived MC metabolites contribute to suppression of pulmonary cells via sequence-specific DNA adducts on the AHREs of the CYP1A1 promoter. This aim has two sub-aims. (i) To test the hypothesis that cells transfected with plasmids containing CYP1A2-derived DNA adducts will display suppression of CYP1A1 transcription in human pulmonary cells (e.g., A549, BEAS-2B) in vitro. (ii) To test the hypothesis that exposure of human lung cells overexpressing CYP1A2 to MC will display attenuation of sustained CYP1A1 induction. The long-term objectives are to: (i) define the molecular mechanisms of regulation of CYP1A1 gene expression by PAHs, (ii) elucidate the possible role of gene- specific DNA adducts in molecular regulation of CYP1A1, and (iii) develop rational strategies for the prevention/treatment of human cancers caused by environmental chemicals.

描述（由申请人提供）：多环芳烃（PAHs）存在于香烟烟雾，颗粒物质和木炭烤肉中。细胞色素P450 (CYP)1A酶在多环芳烃与DNA共价相互作用的代谢产物的激活中起关键作用，这是致癌起始的关键事件。本应用的中心假设是CYP1A1和CYP1A2酶在pah介导的致癌作用中发挥相互作用，并且CYP1A2依赖性MC代谢物有助于在CYP1A1启动子的调控区域形成序列特异性DNA加合物[例如，AHR反应元件（AHREs）]，从而导致MC-DNA加合物抑制CYP1A1基因表达的新机制。提出以下具体目标：1. 确定CYP1A1和1A2酶在多环芳烃介导的肺癌中的机制作用。这个目的有两个子目的：(i)验证缺乏Cyp1a2基因的小鼠更容易受到pah诱导的肺癌和肿瘤发生的影响，而那些缺乏Cyp1a1基因的小鼠比同样暴露的WT小鼠更不容易受到pah诱导的肺癌和肿瘤发生的影响。（ii）验证人源化CYP1A1小鼠比WT小鼠更容易发生肺癌和肿瘤，而人源化CYP1A2小鼠更不容易发生肺癌和肿瘤。2. 探讨MC在体内持续诱导和抑制肝脏和肺部CYP1A1的分子机制。这个目标有两个子目标：(i)为了验证肝脏CYP1A2在机制上有助于MC持续抑制肝脏和肺部CYP1A1的假设。（ii）为了验证MC通过相应启动子的持续转录激活引发持续的人类CYP1A1诱导的假设，在CYP1A1-或CYP1A1 /1a2-null背景下表达人CYP1A1 （hCYP1A1-luc或hCYP1A1-GFP）的转基因人源化小鼠中，肝脏CYP1A2会抑制肝脏和肺部CYP1A1表达的持续诱导。3. 探讨肺CYP1A1诱导抑制的分子机制。我们将验证cyp1a2衍生的MC代谢物通过CYP1A1启动子AHREs上的序列特异性DNA加合物促进肺细胞抑制的假设。这个目标有两个子目标。(i)为了验证这样的假设，即转染含有cyp1a2来源的DNA加合物的质粒的细胞将在体外抑制人肺细胞（例如A549， BEAS-2B）的CYP1A1转录。（ii）验证过表达CYP1A2的人肺细胞暴露于MC会显示持续CYP1A1诱导衰减的假设。长期目标是：(i)确定多环芳烃调控CYP1A1基因表达的分子机制，（ii）阐明基因特异性DNA加合物在CYP1A1分子调控中的可能作用，以及（iii）制定合理的策略来预防/治疗由环境化学物质引起的人类癌症。