Topoisomerase I-directed Anticancer Drugs

拓扑异构酶 I 导向的抗癌药物

• 批准号: 6621894
• 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/6621894
• 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DNA拓扑异构酶I(HTOP1)是喜树碱等抗癌药物的高效新分子靶点。CPTS通过捕获共价反应中间体--三元TOP1可裂解络合物来抑制(毒化)TOP1。这些TOP1可裂解的复合体代表了一种新型的细胞损伤，在杀死肿瘤细胞方面非常有效。除了CPT，越来越多的化合物(TOP1毒物)(如吲哚咔唑、两面针碱、仙人掌、吗啉基阿霉素、阿克拉霉素A、吲哚并[1，2-c]异喹啉、诺伽霉素、放线菌素D、原黄连素、二苯并[c，h]肉桂酚、2-苯基苯并咪唑和三苯并咪唑)已被确定能诱导TOP1可裂解的复合体。尽管TOP1可裂解复合体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尚不清楚。我们的初步研究表明，至少有两种不同的分子机制可能参与了这些不同的TOP1毒物捕获TOP1可裂解复合体的过程。CPTS是TOP1的原型毒物，通过特异性地抑制TOP1催化的断裂/宗教反应的宗教步骤，捕获TOP1可切割的复合体，推测是通过与DNA裂解位点的TOP1-DNA复合体结合(宗教阻断剂)。相比之下，诺加拉霉素是一种DNA结合剂，具有插层和少量沟槽导向的相互作用模式，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可切割复合体。不同的TOP1毒物对TOP1的两种不同中毒模式的识别可能为药物设计和开发提供新的机会。在目前的应用中，我们计划表征这两种TOP1中毒模式，并探索不同TOP1毒物诱导的不同生物学反应。其具体目的是(1)以新霉素为模型，建立TOP1裂解增强剂的DNA曲率模型；(2)探讨不同TOP1毒物诱导的TOP1可裂解复合体的蛋白质构象和细胞修饰。