Alcohol and Iron Derived Oxidant Stress Impact Epigenetic Regulation

酒精和铁源性氧化应激影响表观遗传调控

• 批准号: 7789926
• 负责人: VINCENT E SOLLARS
• 金额: $ 18.47万
• 依托单位: MARSHALL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-01 至 2011-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7789926
• 关键词: Affect; Alcohol consumption; Alcohols; Apoptosis; Area; Attenuated; Biology; Cadherins; Cancer Biology; Carbon; Cells; Chemicals; Chromosomal Instability; Chronic; Cystathionine; DNA; DNA Methylation; Data; Development; Disease; Dysplasia; E-Cadherin; Epigenetic Process; Ethanol; Evaluation; Exposure to; Fibrosis; Gene Expression Regulation; Generations; Genes; Glutathione; H ferritin; Hepatic; Hepatocyte; Hepatocyte Growth Factor; High Pressure Liquid Chromatography; Histologic; Histones; Homocysteine; Homocystine; Human; In Vitro; Individual; Iron; Iron Overload; Lesion; Liver; Long Interspersed Nucleotide Elements; Malignant Neoplasms; Malignant neoplasm of liver; Measures; Metabolism; Methionine; Methods; Methylation; Modeling; Mus; NADH; Oncogenes; Pathway interactions; Phase; Population; Principal Investigator; Process; Property; Proteins; Reaction; Reduced Glutathione; Regulation; Research Personnel; Risk; Risk Factors; Source; Stress; Subarachnoid Hemorrhage; Testing; Tetanus Helper Peptide; Tissues; Transferase; Transgenic Model; adduct; alcohol exposure; angiogenesis; bikunin; bisulfite; cancer type; cell injury; chronic alcohol ingestion; design; folic acid metabolism; glutathione S-transferase pi; high risk; in vivo; inhibitor/antagonist; multidisciplinary; neoplastic; oxidant stress; prevent; promoter; public health relevance; research study; tumor progression

DESCRIPTION (provided by applicant): Chronic alcohol consumption, via several processes, is a risk factor for many cancers, including liver cancer. Iron overload is also a risk factor for liver cancer. RATIONALE. Alcohol is known to have an impact on s-adenosyl methionine (SAMe) synthesis, via pleotropic effects. We posit that iron and its potential to exacerbate oxidant stress generation may also perturb SAMe synthesis through drawing carbon to replenish glutathione (GSH) via the transsulfuration pathway. Such an impact on the methyl donor pool in cells has the potential to affect epigenetic regulation, specifically by attenuating DNA methylation. Epigenetic changes that result in altered expression of critical genes involved in control of proliferation, apoptosis, DNA integrity, angiogenesis and other processes are important to cancer progression. Thus, we hypothesize that changes in GSH levels brought about through exposure to iron derived oxidant stress will stress the pool of homocysteine, potentiating ethanol's inhibition of SAMe leading to alterations in epigenetic regulation reactions that depend on this methyl donor. Homocysteine provides both methionine to produce SAMe and cystathionine to produce GSH. The OBJECTIVE of this exploratory R21 proposal is to conduct key experiments to elucidate the relationship between iron induced oxidant stress and epigenetic regulation in alcohol-related cancer development. In doing so, critical data to support a subsequent R01 application in this area will be generated. Our results will determine the extent to which iron and ethanol converge to impact a fundamentally important pathway and indicate if this in turn may affect processes that are involved with heritable changes in gene regulation. Specific Aim: to determine if ethanol and iron combine to affect methyl donor availability and epigenetic regulation in liver cells in vitro and in vivo. Our preliminary data with a tet-inducible Ferritin H transgenic model indicate we can alter iron availability in a tissue specific manner in vivo. We also demonstrate the capacity to evaluate SAMe and SAH levels in liver tissue, and to analyze alterations in DNA methylation. We will use this expertise in vivo, to test the impact of ethanol and iron independently and together on: A) the formation of pre-neoplastic lesions in the liver; B) SAMe and GSH availability; C) global and gene promoter specific (e-cadherin and HAI-2/PB) DNA methylation; D) oxidant stress as 4-HNE and carbonyl adduct formation, oxidized to reduced GSH ratios, and reductive stress as NAD+/NADH ratios. By answering the question of whether iron and ethanol affect epigenetic regulation, we increase our understanding of the mechanisms by which the microenvironment influences the cell. Given the importance of oxidant stress and epigenetic gene regulation in oncogene stimulation and chromosomal instability, such progress may ultimately help us design strategies to prevent and treat the occurrence of ethanol related cancer development. PUBLIC HEALTH RELEVANCE: Alcohol drinking is known to place the drinker at increased risk for many types of cancer. Individuals that have iron overload disease are at much higher risk of developing liver cancer if they drink alcohol regularly. In addition, how cells handle iron can be influenced by alcohol, making iron an important factor in the development of alcohol associated cancer. Iron acts by causing an increase in a process that damages the cell, called oxidant stress. We think this process may affect a chemical that cells make that is responsible for regulating genes through modifying DNA. We propose to find out if this occurs in liver cells in mice. If this is the case, then we will have identified a mechanism by which iron and oxidant stress may help to drive the formation of cancer in alcohol drinkers. Discovering such a mechanism would give us targets that may help prevent alcohol associated cancer formation.

描述（由申请人提供）：通过几个过程，长期饮酒是许多癌症的风险因素，包括肝癌。铁超载也是肝癌的危险因素。合理性。已知酒精通过多效性效应对S-腺苷甲硫氨酸（SAMe）合成有影响。我们认为，铁及其潜在的加剧氧化应激的产生也可能扰乱SAMe的合成，通过吸收碳补充谷胱甘肽（GSH）通过转硫途径。这种对细胞中甲基供体库的影响有可能影响表观遗传调控，特别是通过减弱DNA甲基化。表观遗传变化导致参与控制增殖、凋亡、DNA完整性、血管生成和其他过程的关键基因的表达改变，对癌症进展很重要。因此，我们假设，通过暴露于铁衍生的氧化应激所带来的GSH水平的变化，将应力池的同型半胱氨酸，增强乙醇的抑制SAMe导致改变表观遗传调控反应，依赖于这个甲基供体。同型半胱氨酸提供甲硫氨酸以产生SAMe和胱硫醚以产生GSH。这项探索性R21提案的目的是进行关键实验，以阐明铁诱导的氧化应激和酒精相关癌症发展中的表观遗传调控之间的关系。在此过程中，将生成支持该领域后续R 01应用的关键数据。我们的研究结果将确定铁和乙醇在多大程度上汇聚到影响一个根本性的重要途径，并表明这反过来是否会影响与基因调控中的遗传变化有关的过程。具体目标：以确定乙醇和铁联合收割机是否在体外和体内影响肝细胞中甲基供体的可用性和表观遗传调节。我们用tet诱导的铁蛋白H转基因模型的初步数据表明，我们可以在体内以组织特异性方式改变铁的可用性。我们还证明了评估肝组织中SAMe和SAH水平以及分析DNA甲基化改变的能力。我们将在体内使用这一专业知识，以测试乙醇和铁单独和共同对以下方面的影响：A）肝脏中肿瘤前病变的形成; B）SAMe和GSH可用性; C）整体和基因启动子特异性（e-钙粘蛋白和HAI-2/PB）DNA甲基化; D）氧化应激（如4-HNE和羰基加合物形成），氧化还原GSH比率，以及还原应激（如NAD+/NADH比率）。通过回答铁和乙醇是否影响表观遗传调控的问题，我们增加了对微环境影响细胞的机制的理解。鉴于氧化应激和表观遗传基因调控在癌基因刺激和染色体不稳定性中的重要性，这些进展最终可能有助于我们设计预防和治疗乙醇相关癌症发展的策略。 公共卫生相关性：众所周知，饮酒会增加饮酒者患多种癌症的风险。患有铁超载疾病的人如果经常饮酒，患肝癌的风险要高得多。此外，细胞处理铁的方式会受到酒精的影响，这使得铁成为酒精相关癌症发展的重要因素。铁的作用是引起一个过程的增加，损害细胞，称为氧化应激。我们认为这一过程可能会影响细胞产生的一种化学物质，这种化学物质负责通过修饰DNA来调节基因。我们建议找出这是否发生在小鼠的肝细胞中。如果是这样的话，那么我们将确定一种机制，铁和氧化应激可能有助于推动饮酒者形成癌症。发现这种机制将为我们提供可能有助于预防酒精相关癌症形成的靶点。