Topoisomerase I-directed Anticancer Drugs

拓扑异构酶 I 导向的抗癌药物

• 批准号: 6687804
• 负责人: LEROY F LIU
• 金额: $ 27.95万
• 依托单位: UNIV OF MED/DENT NJ-R W JOHNSON MED SCH
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-04-01 至 2004-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6687804
• 关键词: DNA binding protein; DNA gyrase; DNA topoisomerases; anthracyclines; antineoplastics; camptothecin; chemical cleavage; conformation; enzyme activity; enzyme mechanism; enzyme model; poisoning; protein degradation; toxin

Human DNA topoisomerase I (hTOP1) is a highly effective new molecular target for anticancer drugs such as camptothecins (CPTs). CPTs inhibit (poison) TOP1 by trapping a covalent reaction intermediate, the ternary TOP1 cleavable complex. These TOP1 cleavable complexes represent a new type of cellular lesion highly effective in killing tumor cells. In addition to CPTs, a growing list of compounds (TOP1 poisons) (e.g. indolocarbazoles, nitidines, saintopin, morpholinyl doxorubicin, aclacinomycin A, indeno[1,2-c]isoquinolines, nogalamycin, actinomycin D, protoberberines, dibenzo[c,h]cinnolines, 2-phenylbenzimidazoles and terbenzimidazoles) have been identified to induce TOP1 cleavable complexes. Despite the clear importance of TOP1 cleavable complexes in tumor cell killing, the molecular mechanism underlying tumor cell killing by TOP1 poisons remains unclear. Our preliminary studies have suggested that at least two distinct molecular mechanisms may be involved in trapping TOP1 cleavable complexes by these different TOP1 poisons. CPTs, the prototypic TOP1 poisons, trap TOP1 cleavable complexes by specifically inhibiting the religation step of the TOP1-catalyzed breakage/religation reaction, presumably by binding to the TOP1- DNA complex at the site of DNA cleavage (religation blockers). By contrast, nogalamycin, a DNA binder with both intercalative and minor groove-directed modes of interactions, traps TOP1 cleavable complexes by inducing a distal DNA bend which favors TOP1 binding/cleavage (cleavage enhancers). The identification of two distinct modes of TOP1 poisoning by different TOP1 poisons may offer new opportunities for drug design and development. In the current application, we plan to characterize these two modes of TOP1 poisoning and to probe the differential biological responses induced by different TOP1 poisons. The specific aims are (1) to establish a DNA curvature model for TOP1 cleavage enhancers using nogalamycin as a model, and (2) to probe the protein conformation and cellular modification of TOP1 cleavable complexes induced by different TOP1 poisons.

人类 DNA 拓扑异构酶 I (hTOP1) 是喜树碱 (CPT) 等抗癌药物的高效新分子靶点。 CPT 通过捕获共价反应中间体（三元 TOP1 可裂解复合物）来抑制（毒害）TOP1。 这些 TOP1 可裂解复合物代表了一种新型的细胞损伤，能够非常有效地杀死肿瘤细胞。 除了 CPT 之外，越来越多的化合物（TOP1 毒物）（例如吲哚并咔唑、两面针碱、圣托品、吗啉基阿霉素、阿克拉霉素 A、茚并[1,2-c]异喹啉、诺加霉素、放线菌素 D、原小檗碱、二苯并[c,h]肉啉、 2-苯基苯并咪唑和三苯并咪唑）已被鉴定可诱导 TOP1 可裂解复合物。 尽管 TOP1 可裂解复合物在肿瘤细胞杀伤中具有明显的重要性，但 TOP1 毒物杀伤肿瘤细胞的分子机制仍不清楚。 我们的初步研究表明，这些不同的 TOP1 毒物捕获 TOP1 可裂解复合物可能涉及至少两种不同的分子机制。 CPT 是原型 TOP1 毒物，通过特异性抑制 TOP1 催化的断裂/再连接反应的再连接步骤来捕获 TOP1 可裂解复合物，大概是通过在 DNA 裂解位点与 TOP1-DNA 复合物结合（再连接阻断剂）。相比之下，诺加霉素（nogalamycin）是一种具有插入和小沟定向相互作用模式的 DNA 结合剂，通过诱导有利于 TOP1 结合/切割（切割增强剂）的远端 DNA 弯曲来捕获 TOP1 可切割复合物。 不同TOP1毒物对两种不同TOP1中毒模式的识别可能为药物设计和开发提供新的机会。 在当前的应用中，我们计划表征这两种 TOP1 中毒模式，并探讨不同 TOP1 毒物引起的差异生物反应。 具体目标是（1）以诺加霉素为模型建立TOP1裂解增强子的DNA曲率模型，以及（2）探讨不同TOP1毒物诱导的TOP1可裂解复合物的蛋白质构象和细胞修饰。