DNA Minor Groove-Targeting Anticancer Agents

描述(申请人提供)：人DNA拓扑异构酶1(TOP1)已被确定为抗癌药物的有效新分子靶点。这些药物通过捕获共价酶-DNA中间体(称为可切割复合体)来抑制(毒害)TOP1，从而刺激蛋白质连接的DNA链断裂，这代表了一种有效杀死肿瘤细胞的新形式的DNA损伤。Terenzimidazoles(TBS)代表了一类新的TOP1毒剂，它们结合在DNA的小凹槽上。部分TB衍生物显示出比临床喜树碱衍生物Topotecan更强的TOP1毒活性和细胞毒性。然而，调控TOP1中毒和TBS细胞毒活性的特定分子相互作用仍然知之甚少。这项建议的总体目标是将TBS开发为有效的抗癌药物。为了实现这一目标，我们将使用广泛的计算、生物物理、生化和细胞技术来实现以下特定目标：(I)确定TOP1靶向以及TOP1介导的TB衍生物的细胞毒性。这些研究旨在评估TBS在完整细胞中捕获TOP1-DNA可切割复合体的能力，并建立其TOP1定向的细胞毒性。(2)确定稳定TB-DNA-TOP1三元可切割复合体的特定药物-酶和药物-DNA相互作用。我们将使用计算技术结合现有的结晶学信息来生成三元Tb-DNA-TOP1可切割络合物的显式溶剂化结构模型，并通过实验评估我们生成的模型的有效性和预测完整性。(3)通过降低TBS的自结合倾向，提高TBS的TOP1毒性和细胞毒性。除了开发具有更高功效的化合物外，这些结构-活性研究还将导致化合物具有更高的水溶解度，这一特征在药物输送的简便性方面具有巨大的潜在价值。(4)确定DNA小沟结合在TBS中毒TOP1中的作用。这些研究旨在加强我们对TBS毒害TOP1的分子机制的了解。从我们提议的研究中收集的信息将使我们能够开发一种合理的方法来设计和开发下一代结核化合物，这些化合物具有可预测的增强TOP1中毒和细胞毒活性。

DESCRIPTION (provided by applicant): Human DNA topoisomerase 1 (TOP1) has been established as an effective new molecular target for anticancer drugs. These agents inhibit (poison) TOP1 by trapping the covalent enzyme-DNA intermediate (termed the cleavable complex), thereby stimulating protein-linked DNA strand breaks, which represent a new form of DNA damage that effectively kills tumor cells. Terbenzimidazoles (TBs) represent a new structural class of TOP1 poisoning agents that bind in the minor groove of DNA. Select TB derivatives exhibit potent TOP1 poisoning activities and cytotoxicities exceeding that of the clinical camptothecin derivative, topotecan. However, the specific molecular interactions that govern the TOP1 poisoning and cytotoxic activities of the TBs are still poorly understood. The overall goal of this proposal is to develop the TBs as effective anticancer agents. Toward this goal, we will employ a broad range of computational, biophysical, biochemical, and cellular techniques to achieve the following specific aims: (i) Determine the TOP1-targeting specificity as well as the TOP1-mediated cytotoxicity of TB derivatives. These studies are designed to evaluate the potencies of the TBs at trapping TOP1-DNA cleavable complexes in intact cells as well as to establish their TOP1-directed cytotoxicities. (ii) Define the specific drug-enzyme and drug-DNA interactions that stabilize the ternary TB-DNA-TOP1 cleavable complex. We will use computational techniques in conjunction with available crystallographic information to generate explicitly solvated structural models of ternary TB-DNA-TOP1 cleavable complexes, and experimentally assess the validities and predictive integrities of our generated models. (iii) Enhance the TOP1 poisoning and cytotoxic efficacies of the TBs by reducing their propensities for self-association. In addition to the development of compounds with increased efficacy, these structure-activity studies will also result in compounds with enhanced water solubilities, a feature that has enormous potential value with regard to the ease of drug delivery. (iv) Determine the role of DNA minor groove binding in the poisoning of TOP1 by TBs. These studies are designed to enhance our understanding of the molecular mechanism by which the TBs poison TOP1. The information gleaned from our proposed studies will enable us to develop a rational approach to the design and development of next generation TB compounds that exhibit predictably enhanced TOP1 poisoning and cytotoxic activities.