Zinc Chemoprevention of Arsenic Co-Carcinogenesis

锌对砷协同致癌作用的化学预防

• 批准号: 9325454
• 负责人: LAURIE G HUDSON
• 金额: $ 31.44万
• 依托单位: UNIVERSITY OF NEW MEXICO HEALTH SCIS CTR
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9325454
• 关键词: Address; Adverse effects; Affinity; Antioxidants; Arsenic; Arsenites; Base Excision Repairs; Benzo(a)pyrene; Binding; Biochemical; Biological Assay; Cadmium; Carcinogens; Cells; Chemoprevention; Chemoprotection; Chemoprotective Agent; Chromium; Coupled; Cysteine; DNA Binding; DNA Binding Domain; DNA Damage; DNA Repair; DNA Repair Gene; DNA Repair Inhibition; DNA Repair Pathway; DNA Sequence Alteration; Elements; Employee Strikes; Epidemiology; Food; Foundations; Goals; Human; Intake; Malignant neoplasm of lung; Malignant neoplasm of urinary bladder; Measures; Metals; Methods; Molecular Target; Mus; Mutagenesis; Nucleotide Excision Repair; Outcome; Outcome Study; Pathway interactions; Play; Poly(ADP-ribose) Polymerases; Population; Prevention strategy; Proteins; Publishing; Radiation Induced DNA Damage; Reporting; Research; Risk; Role; Skin; Skin Cancer; Skin Carcinogenesis; Skin Neoplasms; Smoking; Soil; Solid; Sun Exposure; Testing; UV induced; Ultraviolet Rays; Water; Work; Xeroderma Pigmentosum; Zinc; Zinc Fingers; Zinc supplementation; base; carcinogenesis; carcinogenicity; cost; enzyme activity; epidemiologic data; experimental study; exposed human population; functional restoration; genome integrity; genotoxicity; improved; in vivo; innovation; novel; oxidative DNA damage; prevent; public health relevance; repaired; synergism; synthetic peptide; tumorigenesis

DESCRIPTION (provided by applicant): There is strong evidence that in addition to the known direct carcinogenic actions of high arsenic concentrations, low, non-carcinogenic levels of arsenic synergize with other DNA-damaging agents such as benzo[a]pyrene and ultraviolet radiation (UVR) to enhance carcinogenesis. This observation has led to the identification of arsenic as a co-carcinogen. One mode of action to account for arsenic co-carcinogenesis is inhibition of DNA repair proteins containing zinc finger DNA binding motifs. Research from our lab demonstrates that: i) zinc finger proteins with e3 cysteine residues are direct molecular targets for arsenite binding, including xeroderma pigmentosum group A (XPA) and poly(ADP-ribose)polymerase (PARP)-1, which are the critical proteins for nucleotide excision repair (NER) and base excision repair (BER) respectively; ii) low levels of arsenite enhance UVR-induced photoproducts and oxidative DNA damage; and iii) supplemental zinc prevents arsenite effects on PARP-1 inhibition, enhancement of UVR-induced DNA damage and mutations. We hypothesize that zinc supplement will prevent arsenite enhancement of UVR-induced skin tumors by restoring the DNA repair capabilities in both BER and NER pathways. The proposed study will address a novel mechanism by which zinc may act to prevent arsenic-augmented carcinogenesis through interaction with distinct molecular targets in DNA repair pathways. In Aim 1, we will use multiple analytical approaches to definitively examine the competitive interaction of arsenite and zinc with synthetic peptides representing the PARP-1 and XPA zinc finger domains and with purified protein. These findings will be coupled with functional assays to establish the consequences of any identified differences in arsenite affinity for target proteins and zinc interactions. Aim 2 will analyze PARP-1 and XPA isolated from treated cells to measure arsenic and zinc binding to protein and the corresponding functional consequences to reveal the specific mechanism by which zinc reverses the arsenic effects. In Aim 3, we will validate PARP-1 and XPA as arsenic targets in vivo using biochemical methods, and test the hypothesis that zinc will prevent arsenic enhancement of UVR-induced DNA damage and skin tumors. The outcomes from the proposed studies are expected to demonstrate the capability of zinc to restore PARP-1 and XPA activity leading to improved genomic integrity and a decrease in the arsenic contribution to co-carcinogenesis. Although zinc has been considered chemoprotective largely through its reported general antioxidant activities, this proposal is innovative by focusing on a novel mechanism by which zinc prevents arsenite binding with specific zinc finger DNA repair protein targets, thus reversing the arsenite inhibition of DNA repair. This study will provide the solid foundations for a clear mechanistic understanding of how supplemental zinc reduces arsenic co-carcinogenesis, and provide the proof of principle for the potential of zinc supplement to prevent arsenic co-carcinogenesis. If validated, supplemental zinc could represent a low cost and easily implemented strategy for chemoprevention in arsenic exposed populations.

描述（由申请人提供）：有强有力的证据表明，除了已知的高浓度砷具有直接致癌作用外，低浓度、非致癌水平的砷还可与其他 DNA 损伤剂（如苯并[a]芘）和紫外线辐射 (UVR) 协同作用，从而增强致癌作用。这一观察结果导致砷被鉴定为一种共同致癌物。砷协同致癌的一种作用方式是抑制含有锌指 DNA 结合基序的 DNA 修复蛋白。我们实验室的研究表明： i) 带有 e3 半胱氨酸残基的锌指蛋白是亚砷酸盐结​​合的直接分子靶点，包括 A 组着色性干皮病 (XPA) 和聚（ADP-核糖）聚合酶 (PARP)-1，它们分别是核苷酸切除修复 (NER) 和碱基切除修复 (BER) 的关键蛋白； ii) 低水平的亚砷酸盐增强了 UVR 诱导的光产物和氧化 DNA 损伤； iii) 补充锌可防止亚砷酸盐对 PARP-1 抑制、增强 UVR 诱导的 DNA 损伤和突变的影响。我们假设锌补充剂将通过恢复 BER 和 NER 途径中的 DNA 修复能力来防止亚砷酸盐增强 UVR 诱导的皮肤肿瘤。拟议的研究将探讨一种新机制，通过该机制，锌可以通过与 DNA 修复途径中的不同分子靶标相互作用来预防砷增强的致癌作用。在目标 1 中，我们将使用多种分析方法来明确检查亚砷酸盐和锌与代表 PARP-1 和 XPA 锌指结构域的合成肽以及纯化蛋白质的竞争性相互作用。这些发现将与功能测定相结合，以确定亚砷酸盐对目标蛋白的亲和力和锌相互作用的任何已识别差异的后果。目标 2 将分析从处理细胞中分离的 PARP-1 和 XPA，以测量砷和锌与蛋白质的结合以及相应的功能后果，以揭示锌逆转砷效应的具体机制。在目标 3 中，我们将使用生化方法验证 PARP-1 和 XPA 作为砷的体内靶标，并检验锌会阻止砷增强 UVR 诱导的 DNA 损伤和皮肤肿瘤的假设。拟议研究的结果预计将证明锌恢复 PARP-1 和 XPA 活性的能力，从而改善基因组完整性并减少砷对协同致癌作用的影响。尽管锌主要通过其报道的一般抗氧化活性被认为具有化学保护作用，但该提案具有创新性，它关注的是一种新机制，通过该机制，锌可以防止亚砷酸盐与特定的锌指 DNA 修复蛋白靶标结合，从而逆转亚砷酸盐对 DNA 修复的抑制。这项研究将为清楚地了解补充锌如何减少砷协同致癌的机制提供坚实的基础，并为补充锌预防砷协同致癌的潜力提供原理证明。如果得到验证，补充锌可能代表一种低成本且易于实施的砷暴露人群化学预防策略。