DNA LESIONS AS ENDOGENOUS TOPOISOMERASE POISONS

DNA 损伤作为内源性拓扑异构酶毒物

• 批准号: 6131038
• 负责人: NEIL OSHEROFF
• 金额: $ 25.77万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-05-01 至 2004-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6131038
• 关键词: DNA binding protein; DNA damage; DNA repair; DNA replication; DNA topoisomerases; Drosophilidae; Saccharomyces cerevisiae; adduct; antineoplastics; cell death; chemical binding; chemical cleavage; cytotoxicity; enzyme activity; enzyme induction /repression; enzyme mechanism; genetic recombination; mutant; pharmacokinetics; tissue /cell culture

DESCRIPTION (As Adapted From the Investigator's Abstract): Topoisomerase II is an essential enzyme that is required for proper chromosome structure and segregation and plays important roles in DNA replication and recombination. Beyond its critical cellular functions, topoisomerase II is the primary target for some of the most active and widely prescribed drugs used for the treatment of human cancers. These agents elicit their cytotoxic effects by a mechanism that is markedly different than that of other drugs. Rather than inhibiting the catalytic activity of topoisomerase II, anticancer drugs targeted to the enzyme dramatically increase levels of covalent topoisomerase II-cleaved DNA complexes that are normal, but fleeting, catalytic intermediates. When the resulting topoisomerase II-associated double-stranded DNA breaks are present in high concentrations, they generate mutations, chromosomal translocations, and trigger cell death pathways. Because topoisomerase II-targeted anticancer drugs convert this dispensable enzyme into a potent physiological toxin, they are referred to as topoisomerase II poisons. Although topoisomerase II is one of the most important targets for cancer chemotherapy, there is compelling circumstantial evidence that the enzyme also has the potential to trigger the disease. Together with the unique mechanism of action of topoisomerase II poisons, this suggests that topoisomerase II-targeted drugs may represent exogenous counterparts of cellular components that induce DNA recombination, mutagenesis, or cell death pathways. Previous results form this laboratory indicated that abasic sites, the most commonly formed lesions in DNA, stimulate topoisomerase II-mediated double-stranded DNA cleavage with a potency that is greater than 1000-fold higher than that of etoposide, one of the most widely prescribed anticancer drugs in clinical use. Therefore, the ultimate goals of the proposal are to further define interactions between topoisomerase II and DNA damage and to determine whether DNA lesions function in vivo as endogenous topoisomerase II poisons. The specific aims of this proposal are to: 1) further define the spectrum of DNA damage that alters the catalytic function of type II topoisomerases; 2) define the mechanism by which DNA lesions enhance topoisomerase II-mediated DNA cleavage; 3) determine whether abasic intermediates generated by base excision repair can trigger the formation of permanent topoisomerase II-mediated double-stranded DNA breaks; and 4) determine whether DNA lesions act as topoisomerase II poisons in the cell. The primary enzymological model for this study will be human topoisomerase II alpha and beta. Physiological studies will employ human cell lines and yeast (Saccharomyces cerevisiae). Cellular DNA damage will be induced by a combination of chemical and genetic approaches.

描述（根据调查员的摘要改编）：拓扑异构体II是 适当的染色体结构所需的必需酶和 隔离和在DNA复制和重组中起重要作用。 除了其关键细胞功能之外，拓扑异构酶II是主要目标 对于一些用于治疗的最活跃和规定的药物 人类癌。这些药物通过一种机制引起其细胞毒性作用 这与其他药物明显不同。而不是抑制 拓扑异构酶II的催化活性，针对酶的抗癌药物 大幅提高共价拓扑异构酶II-旋转的DNA复合物的水平 正常但短暂的催化中间体。当结果时 拓扑异构酶II相关的双链DNA断裂存在于高中 浓度，它们会产生突变，染色体易位和 触发细胞死亡途径。因为拓扑异构酶II靶向抗癌药 将这种可分配酶转化为有效的生理毒素，它们是 称为拓扑异构酶II毒药。虽然拓扑异构酶II是 癌症化学疗法的最重要靶标，具有引人注目 间接证据表明该酶也有可能触发 疾病。加上拓扑异构酶II的独特作用机理 毒药，这表明拓扑异构酶II靶向药物可能代表 诱导DNA重组的细胞成分的外源对应物， 诱变或细胞死亡途径。以前的结果构成了这个实验室 表明abasic部位是DNA中最常见的病变，刺激 拓扑异构酶II介导的双链DNA裂解，效力为 比依托泊苷高1000倍，这是最广泛的 在临床用途中开了抗癌药。因此，最终目标 该提议是为了进一步定义拓扑异构酶II与 DNA损伤并确定DNA病变在体内是否起作用 拓扑异构酶II毒药。该提议的具体目的是：1）进一步 定义改变II型催化功能的DNA损伤的光谱 拓扑异构酶； 2）定义DNA病变增强的机制 拓扑异构酶II介导的DNA裂解； 3）确定是否有无聊 基础切除修复产生的中间体可以触发形成 永久性拓扑异构酶II介导的双链DNA断裂；和4） 确定DNA病变是否充当细胞中的拓扑异构酶II毒物。这 这项研究的主要酶学模型将是人拓扑异构酶II alpha 和beta。生理研究将采用人类细胞系和酵母 （酿酒酵母）。细胞DNA损伤将由A诱导 化学和遗传方法的结合。