HUMAN CELL MODELS--LONGTERM LOW DOSE EXPOSURES AND MUTANT RESISTANT STATE

人体细胞模型——长期低剂量暴露和突变抵抗状态

• 批准号: 6338776
• 负责人: William G Thilly
• 金额: $ 22.21万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-03 至 2003-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6338776
• 关键词: DNA damage; DNA repair; adduct; air pollution; air sampling /monitoring; benzopyrenes; cell line; cytochrome P450; dosage; environmental toxicology; gender difference; gene expression; lung injury; mutagens; polymerase chain reaction; toxin metabolism

We have discovered that when our human cell line, AHH-1, which expresses cytochrome P-450 1A1, is exposed continuously to low concentrations of potent airborne mutagens such as benzo(a)pyrene and naphtho(a)pyrene that they switch from a high mutation rate to a low mutation rate after 5 days. This low mutations rate is only some three fold higher than seen for spontaneous mutation in the concurrent untreated controls. Studies with radioactive benzo(a)pyrene show that the rate of DNA adduct formation is unchanged by this phenomenon. The ratio of the rate of mutation relative to the rate of constant DNA adduction is changed by a factor of four suggesting induction of a post-DNA adduction process such as DNA repair is occurring. Because such a phenomenon would, if occurring in vivo, represent a major physiologic response protecting against induction of mutations by airborne toxicants. Our studies so far establish that the induction of the mutation-resistance by benzo(a)pyrene confers cross-resistance to mutation by the potent airborne mutagen, cyclopenta[c,d]pyrene. Secondly, we have found that another potent airborne mutagen naphtho(a)pyrene induces resistance to mutation in a time dependent pattern similar to that of benzo(a)pyrene. Finally, we have found human cell lines derived from AHH-1 which are markedly sensitive to mutation by air sample extract under short term high dose conditions giving use a useful mode for proposed long term dose mimicking conditions of samples, source samples and their extracts and subfractions on these human cells under these long term low dose conditions which more closely approximate the conditions of exposure in the human bronciolar tree, (b) discover it the "mutation resistant state" is induced by exposure to raw air particulates, by particulate extracts and by particulate extract subfractions, and (c.) carry out appropriate studies of the process at the cellular and molecular levels.

我们发现，当我们的人类细胞系 AHH-1 表达 细胞色素 P-450 1A1，连续暴露于低浓度 强效空气诱变剂，例如苯并(a)芘和萘并(a)芘 5 天后，它们从高突变率转变为低突变率。 这种低突变率仅比所见的高三倍左右 同时未治疗的对照中发生自发突变。研究与 放射性苯并(a)芘表明DNA加合物形成的速率为 这种现象没有改变。相对突变率之比 恒定 DNA 加合速率改变了四倍 表明 DNA 加合后过程（例如 DNA 修复）的诱导是 发生。 因为这种现象如果发生在体内，将代表一个重大的 防止空气传播诱发突变的生理反应 有毒物质。到目前为止，我们的研究表明，诱导 苯并(a)芘的突变抗性赋予对突变的交叉抗性 由强效空气诱变剂环戊[c,d]芘引起。其次，我们有 发现另一种有效的空气诱变剂萘并（a）芘诱导 以类似于时间依赖模式的突变抵抗力 苯并(a)芘。最后，我们找到了源自AHH-1的人类细胞系 对短时间下空气样本提取物的突变非常敏感 长期高剂量条件为建议的长期使用提供了有用的模式 样品、源样品及其提取物的剂量模拟条件 以及在这些长期低剂量下对这些人体细胞的亚组分 更接近暴露条件的条件 人类细支气管树，(b) 发现它的“突变抵抗状态” 是由暴露于原始空气颗粒物、颗粒提取物引起的 和通过颗粒提取物亚级分，并且(c.)进行适当的 在细胞和分子水平上研究该过程。