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）：通过多种过程，长期的饮酒是包括肝癌在内的许多癌症的危险因素。铁超负荷也是肝癌的危险因素。理由。众所周知，酒精会对S-腺苷蛋氨酸（相同）的合成产生影响。我们认为，铁及其加剧氧化应激产生的潜力也可能通过绘制碳通过跨硫化途径来补充谷胱甘肽（GSH）来扰动相同的合成。对细胞中甲基供体池的这种影响具有影响表观遗传调节的潜力，特别是通过减弱DNA甲基化。表观遗传学变化导致对控制，凋亡，DNA完整性，血管生成和其他过程的关键基因表达的改变对癌症进展至关重要。因此，我们假设通过暴露于铁衍生的氧化剂应激而导致的GSH水平的变化将压力同型半胱氨酸的抑制，从而增强了乙醇对相同的抑制，从而导致表观遗传调节反应的改变，这取决于该甲基供体。同型半胱氨酸提供蛋氨酸可产生相同的甲氨酸和胱胺苷可产生GSH。该探索性R21提案的目的是进行关键实验，以阐明与酒精相关癌症发展中铁诱导的氧化剂应激与表观遗传调节之间的关系。这样一来，将生成支持该领域中后续R01应用程序的关键数据。我们的结果将确定铁和乙醇融合以影响根本重要的途径的程度，并指出这是否又可能影响与基因调节的可遗传变化有关的过程。具体目的：确定乙醇和铁是否合并以影响肝细胞体外和体内肝细胞中的甲基供体的可用性和表观遗传调节。我们使用可诱导的铁蛋白H转基因模型的初步数据表明，我们可以在体内以组织特定方式改变铁的可用性。我们还证明了在肝组织中评估相同水平和SAH水平的能力，并分析DNA甲基化的改变。我们将在体内使用这种专业知识，以独立并共同对乙醇和铁的影响进行：a）肝脏中肿瘤前病变的形成； b）相同和GSH的可用性； C）全球和基因启动子特异性（E-钙粘蛋白和HAI-2/PB）DNA甲基化； d）氧化应激为4-HNE和羰基加合物的形成，氧化为降低的GSH比，还原应力为NAD+/NADH比。通过回答铁和乙醇是否影响表观遗传调节的问题，我们可以提高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节在癌基因刺激和染色体不稳定性中的重要性，这种进步最终可能有助于我们设计策略，以预防和治疗与乙醇相关的癌症发育的发生。 公共卫生相关性：众所周知，饮酒会使饮酒者面临许多类型癌症的风险。如果经常喝酒，患有铁超负荷疾病的个体患肝癌的风险要高得多。此外，细胞如何处理铁可以受到酒精的影响，使铁成为与酒精相关癌症发展的重要因素。铁在损害细胞的过程中增加称为氧化应激的过程来起作用。我们认为，此过程可能会影响细胞使该化学物质通过修饰DNA来调节基因的化学物质。我们建议找出小鼠肝细胞中是否发生这种情况。如果是这种情况，那么我们将确定一种机制，通过该机制，铁和氧化剂应激可能有助于推动酒精饮用者的癌症形成。发现这种机制将为我们提供可能有助于防止与酒精相关的癌症形成的目标。