CYCLE-DEPENDENT MECHANISMS OF CHEMICAL CLASTOGENESIS

化学断裂的周期依赖性机制

• 批准号: 6102317
• 负责人: William K. Kaufmann
• 金额: $ 17.31万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-05-01 至 2001-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6102317
• 关键词: DNA damage; DNA repair; DNA replication; Li Fraumeni syndrome; adduct; ataxia telangiectasia; autoradiography; benzopyrenediol epoxide; cell cycle; cell cycle proteins; cell growth regulation; cell line; cellular oncology; chemical carcinogen; chemical carcinogenesis; chromosome aberrations; fibroblasts; light microscopy; neoplasm /cancer genetics; radiation carcinogenesis; sedimentation velocity; synchronous cell division; tissue /cell culture; ultraviolet radiation

This project is concerned with the mechanisms whereby chemical carcinogens and UV radiation induce chromosomal aberrations in human fibroblast and how cell cycle checkpoint controls protect against induced clastogenesis. Structural alterations in chromosomes typify cancer and human genetic disease syndromes which include chromosomal fragility as part of their phenotypes. Environmental carcinogens such as polynuclear aromatic hydrocarbons, nitrosamines and ultraviolet radiation induce chromosome aberrations (CA's) in an S-phase-dependent process. Carcinogen-DNA adducts and UV-induced pyrimidine dimers do not produce CA's directly; the primary lesion in DNA is converted to a DNA double strand break in a process involving DNA replication. Replication-dependent DNA double strand breaks (dsb), if left unrepaired through G2, are seen as chromatid breaks when cells enter mitosis. DNA repair pathways reduce the yields of induced CA's by removing the primary DNA lesions before DNA replication and by rejoining the replication-dependent DNA dsb before mitosis. Pathways of cell cycle checkpoint control impose delays in progression through the cell cycle to provide more time for excision repair and rejoining of breaks. Ataxia telangiectasia (AT) cells, which display chromosomal instability and UV radiation hypersensitivity, also exhibit a defect in checkpoint control and fail to impose proper cell cycle delays in response to DNA damage. The contribution of the cycle delay responses to protection against clastogenesis will be determined by comparing normal human and AT fibroblasts strains. If AT cells are unable to induce cell cycle delays in response to DNA damage and display elevated yields of carcinogen induced CA's, a protective role for cell cycle delays in chemical and radiation clastogenesis would be suggested. Cell division control (CDC) kinase activities will be examined during carcinogen-induced delays to establish the biochemical signatures of cycle-delay responses in human cells. The DNA dsb that develop during replication of damaged DNA will be quantified by neutral elution chromatography to determine whether normal and AT cells develop similar levels of pre-clastogenic damage carcinogen exposure. Fibroblasts from patients with Li-Fraumeni familial cancer syndrome will also be tested for loss of specific elements of checkpoint control in response to DNA damage. Immortal LFS fibroblasts which have lost the wild- type p53 allele also have lost the G1 checkpoint control function. Demonstration of enhanced clastogenesis in these immortal LFS would lend further support to a hypothesis that checkpoint controls protect against carcinogen-induced genetic damage. This project will establish whether chemical carcinogens and UV induce chromosome aberrations in human fibroblasts by an S-phase dependent mechanism and test whether cell cycle checkpoint controls protect against cell cycle-dependent clastogenesis.

该项目与化学致癌物的机制有关 紫外线辐射诱导人成纤维细胞中的染色体畸变以及如何 细胞周期检查点控制可预防诱导的碎屑发生。 染色体的结构改变代表癌症和人类遗传 疾病综合征包括染色体脆性作为其疾病易变症 表型。 环境致癌物，例如多核芳香族 碳氢化合物，硝基胺和紫外线辐射诱导染色体 在S期依赖性过程中的畸变（CA）。 致癌-DNA加合物 紫外线诱导的嘧啶二聚体不会直接产生Ca。主要 DNA中的病变在过程中转化为DNA双链断裂 涉及DNA复制。 依赖复制的DNA双链断裂 （DSB）如果未经G2的未修复，则将其视为染色单体断裂。 细胞进入有丝分裂。 DNA修复途径降低了诱导CA的产量 通过在DNA复制之前去除主要的DNA病变并通过重新加入 有丝分裂之前，依赖复制的DNA DSB。 细胞周期的途径 检查点控制在整个细胞周期中迫使延迟到 提供更多时间进行切除修复和重新加入休息时间。 共济失调 毛细血管理（AT）细胞，它们表现出染色体不稳定性和紫外线 辐射超敏反应，在检查点控制和 无法对DNA损伤施加适当的细胞周期延迟。 这 周期延迟响应对保护的贡献 策区发生将通过比较正常人和在 成纤维细胞菌株。如果在细胞处无法诱导细胞周期延迟 对DNA损伤的反应，并显示致癌的产量升高 CA，是化学和辐射中细胞周期延迟的保护作用 将提出碎石生成。 细胞分裂控制（CDC）激酶 在致癌诱导的延迟期间将检查活动以建立 人类细胞中循环延迟反应的生化特征。 这 在受损DNA复制过程中发展的DNA DSB将被定量 通过中性洗脱色谱法确定正常和在细胞上是否 形成类似水平的塑料前损伤致癌物暴露。 Li-Fraumeni家族癌综合征患者的成纤维细胞将 还可以测试是否丢失了检查点控制的特定元素 对DNA损伤的反应。 不朽的LFS成纤维细胞失去了野外的 类型p53等位基因也丢失了G1检查点控制功能。 这些不朽的LFS中增强的碎屑发生的证明将借出 对检查点控制防止的假设的进一步支持 致癌引起的遗传损害。 该项目将确定是否 化学致癌物和紫外线诱导人类的染色体畸变 通过S期依赖机制进行成纤维细胞，并测试细胞周期是否 检查点控制着防止细​​胞周期依赖性的碎屑发生。