Lipid-Peroxidation Induced Cyclic Adducts in Hepatocarcinogenesis

脂质过氧化诱导的环状加合物在肝癌发生中的作用

• 批准号: 7656102
• 负责人: FUNG-LUNG CHUNG
• 金额: $ 46.38万
• 依托单位: GEORGETOWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2014-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7656102
• 关键词: Acrolein; Affect; Aldehydes; Animal Model; Animals; Antioxidants; Base Excision Repairs; Binding; Binding Sites; Biological; Biological Assay; Carcinogens; Cells; Chemopreventive Agent; Chronic; Cinnamon - dietary; Classification; Codon Nucleotides; Copper; DNA; DNA Damage; DNA lesion; Data; Defect; Deoxyguanosine; Development; Diagnostic Neoplasm Staging; Fatty Liver; Frequencies; Goals; Green tea; Guanine; Harvest; Hepatocarcinogenesis; Human; In Vitro; Inbred LEC Rats; Incidence; Individual; Knockout Mice; Lesion; Life; Ligation; Light; Link; Lipid Peroxidation; Liver; Liver neoplasms; Long-Evans Rats; Lung; Malignant Neoplasms; Malignant neoplasm of liver; Maps; Mediating; Modeling; Monitor; Mus; Mutate; Mutation; Mutation Spectra; Nucleotide Excision Repair; Obesity; Organ; Oxidative Stress; Pathway interactions; Pattern; Polyphenon E; Polyunsaturated Fatty Acids; Primary carcinoma of the liver cells; Risk Factors; Rodent; Role; Skin Carcinogenesis; Slice; Staging; TP53 gene; Thioctic Acid; Thymine; Tissues; Transgenic Organisms; Tumor Tissue; Tumor stage; UV Radiation Exposure; UV induced; Vitamin E; XPA gene; adduct; base; carcinogenesis; human DNA; human tissue; in vivo; oxidation; repaired; tool; tumor; tumorigenesis

DESCRIPTION (provided by applicant): Cyclic 1,N2-propanodeoxyguanosine adducts of acrolein (Acr-dG) and trans-4-hydroxy-2-nonenal (HNE-dG) derived from lipid peroxidation have been detected as endogenous DNA lesions in rodent and human tissues. However, their roles in carcinogenesis are still not clearly understood. Recent in vitro studies in cultured human cells and in DNA fragments containing the human p53 gene have shown that Acr and HNE can bind to the p53 gene preferentially at guanines in a sequence-selective manner and that the binding patterns are similar to p53 mutation hotspots observed in certain human cancers, suggesting the possible roles of Acr-dG and HNE-dG in carcinogenesis. However, no in vivo studies have been conducted to directly examine cyclic adducts in tissues where tumors develop in a relevant animal tumorigenesis model. These studies are important because they provide strong evidence directly linking adducts with mutations and tumor formation in the target tissue. In this application, we propose to use genetically defected Long Evans Cinnamon (LEC) rats and transgenic XPA-deficient (XPA-/-) mice, both of which are highly prone to spontaneous liver cancer without carcinogen treatment, to investigate the roles of Acr-dG and HNE-dG as endogenous DNA lesions in carcinogenesis. LEC rats are inflicted with heightened lipid peroxidation in the liver as a result of abnormal copper accumulation, whereas XPA(-/-) mice are deficient in nucleotide excision repair (NER) which is important for removing Acr- and HNE-dG adducts. Our hypothesis is that the formation of the cyclic adducts will be increased and these adducts will accumulate in the liver DNA of these animals compared with the wild-type Long Evans (LE) rats and XPA(+/+) mice and that the increased formation of these adducts underlies the mechanisms for liver carcinogenesis. We will carry out the following aims to examine this hypothesis. In Aim 1, we will conduct tumor bioassays in LEC rats and XPA(-/-) mice and their normal strains and study throughout their lives the relationships of cyclic adducts in the liver DNA with liver carcinogenesis at different stages; In Aim 2, we will map Acr and HNE adduct binding sites in the p53 gene of the liver DNA from LEC rats and XPA (-/-) mice during the tumor bioassays and compare their binding sites with the p53 mutational spectra of the liver tumors harvested at the termination of bioassays. In Aim 3, we will investigate the effects of antioxidants on the formation of cyclic adducts in the liver DNA and on the development of spontaneous liver cancers in these animals. The data generated from these studies will help us to understand the roles of endogenous cyclic Acr-dG and HNE-dG adducts from lipid peroxidation in hepatocarcinogenesis.

描述（由申请人提供）：丙烯醛（Acr-dG）和反式4-羟基-2-壬烯醛（HNE-dG）的环1，n2 -丙烷脱氧鸟苷加合物来源于脂质过氧化，已被检测为啮齿动物和人体组织的内源性DNA病变。然而，它们在致癌作用中的作用仍不清楚。最近在体外培养的人类细胞和含有人类p53基因的DNA片段中进行的研究表明，Acr和HNE可以在鸟嘌呤上以序列选择性的方式优先与p53基因结合，并且其结合模式与某些人类癌症中观察到的p53突变热点相似，提示Acr- dg和HNE- dg可能在致癌过程中起作用。然而，在相关的动物肿瘤发生模型中，还没有进行直接检测肿瘤组织中环加合物的体内研究。这些研究很重要，因为它们提供了强有力的证据，直接将加合物与靶组织中的突变和肿瘤形成联系起来。在本应用中，我们拟采用基因缺陷的Long Evans Cinnamon （LEC）大鼠和转基因XPA-缺陷（XPA-/-）小鼠，这两种小鼠在未经致癌物治疗的情况下极易发生自发性肝癌，研究Acr-dG和ene - dg作为内源性DNA病变在肝癌发生中的作用。LEC大鼠由于异常的铜积累而导致肝脏脂质过氧化升高，而XPA（-/-）小鼠缺乏核苷酸切除修复（NER），这对去除Acr-和HNE-dG加合物很重要。我们的假设是，与野生型Long Evans （LE）大鼠和XPA（+/+）小鼠相比，环状加合物的形成会增加，这些加合物会在这些动物的肝脏DNA中积累，这些加合物的形成增加是肝癌发生机制的基础。我们将执行以下目的来检验这一假设。在Aim 1中，我们将对LEC大鼠和XPA（-/-）小鼠及其正常品系进行肿瘤生物测定，研究其一生中肝脏DNA环加合物与不同阶段肝癌发生的关系；在Aim 2中，我们将在肿瘤生物测定期间绘制LEC大鼠和XPA（-/-）小鼠肝脏DNA中p53基因的Acr和HNE加合物结合位点，并将其结合位点与生物测定终止时收获的肝脏肿瘤的p53突变谱进行比较。在目标3中，我们将研究抗氧化剂对肝脏DNA中环状加合物形成的影响以及对这些动物自发性肝癌发展的影响。这些研究产生的数据将帮助我们了解脂质过氧化内源性环Acr-dG和HNE-dG加合物在肝癌发生中的作用。