AFFECTS OF ARSENITE ON DNA DAMAGE INDUCIBLE RESPONSE

亚砷酸盐对 DNA 损伤诱导反应的影响

• 批准号: 2554836
• 负责人: Toby G. Rossman
• 金额: $ 18.74万
• 依托单位: NEW YORK UNIVERSITY SCHOOL 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: 1998-01-01 至 2000-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2554836
• 关键词: DNA damage; DNA repair; apoptosis; arsenic; ascorbate; cell cycle; cell transformation; chronic disease /disorder; fibroblasts; gene expression; gene mutation; genetic regulation; human tissue; keratinocyte; molecular cloning; mutagens; natural gene amplification; oxidative stress; tissue /cell culture; tumor suppressor genes; tumor suppressor proteins; water pollution

DESCRIPTION: Arsenic exposure via drinking water is associated with increased risk of human cancers, as well as a number of other dysfunctions. The investigators have demonstrated that although arsenite (the likely carcinogenic form of arsenic) is not a gene mutagen, it acts as a comutagen by interfering with DNA repair. However, DNA repair enzymes in vitro are not sensitive to arsenite implying that arsenite s effect on DNA repair in cells is not via enzyme inhibition. The investigators suggest that inhibition of DNA repair by arsenite results from an interference with p53-dependent pathways controlling cellular responses to DNA damage. Human exposure to arsenic, e.g. in drinking water, occurs over a long period of time. This proposal will address the effects of long term, low level arsenite treatment of a number of p53-related endpoints. Because they have found that rodent cells exposed to low levels of arsenite develop tolerance, whereas human cells do not, the emphasis will be on human cells. The specific aims are first to determine the ability of arsenite and its metabolite dimethylarsinic acid (DMAA) to interfere with the cellular resoponse to x-ray-induced DNA damage in normal human diploid fibroblasts and keratinocytes. DNA-damage-in-ducible responses include transient cell cycle arrest, increase in p53 protein abundance, and the up-regulation of genes downstream of p-53(particularly gadd45 and p21). Second, the investigators will determine whether human cells which have undergone mutation, gene amplification, or transformation as a result of long term, low level arsenite or DMAA exposure(alone or with low doses of UVB) show increased frequencies of genomic instability compared with similarly treated cells which were not altered. Third, they will study the role of oxidant stress in arsenite's action by determining whether any effects seen in aims 1 (where p53-dependent fucntions are measured) and 2 (where genetic effects are measured) can be blocked by ascorbate, atocopherol, or N-acetyl-cysteine. Lastly, by expression cloning for genes which confer resistance to arsenite, they have cloned 2 cDNAs, fau (a purported tumor suppressor gene) and asr2 (whose product plays a role in apoptosis). The investigators will determine whether fau or asr2 will, when overexpressed, contribute to genomic instability in human cells.

描述：通过饮用水暴露砷与 人类癌症的风险增加，以及许多其他功能障碍。 调查人员表明，尽管阿森特（可能 致癌形式的砷）不是基因诱变剂，它是合理的 通过干扰DNA修复。 然而，体外的DNA修复酶是 对砷不敏感，暗示砷对DNA修复的影响 细胞不是通过酶抑制。 调查人员建议 通过干扰对DNA修复的抑制作用 依赖p53的途径，控制了对DNA损伤的细胞反应。 人类 暴露于砷，例如在饮用水中，很长一段时间 时间。 该建议将解决长期，低级别的影响 许多与P53相关的终点的砷处理。 因为他们有 发现暴露于低水平的砷的啮齿动物细胞会产生耐受性， 尽管人类细胞不存在，但重点将放在人类细胞上。 这 具体目的是首先确定砷及其的能力 代谢物二甲基苯胺酸（DMAA）干扰细胞 在正常人二倍体成纤维细胞中，对X射线诱导的DNA损伤的响应 和角质形成细胞。 DNA破坏可引起的响应包括瞬态细胞 周期停滞，p53蛋白丰度的增加以及上调的上调 P-53的下游基因（尤其是GADD45和P21）。 第二， 研究人员将确定是否经历过的人类细胞 长期的突变，基因扩增或转化， 低水平的砷或DMAA暴露（单独或使用低剂量的UVB）显示 与经过类似处理的基因组不稳定性的频率增加 没有改变的细胞。 第三，他们将研究氧化剂的作用 通过确定目标中是否看到任何影响，砷的行动中的压力 1（测量了p53依赖性诱导量）和2（其中遗传效应 测量）可以被抗坏血酸盐，环保酚或 N-乙酰基半胱氨酸。 最后，通过表达克隆的基因 对砷的耐药性，它们克隆了2个cDNA，fau（据称的肿瘤 抑制基因）和ASR2（其产物在凋亡中起作用）。 这 调查人员将确定FAU或ASR2是否会过表达时，是否会 有助于人类细胞中的基因组不稳定性。