选择性PARP1抑制剂的设计合成及结合热力学和动力学研究

Poly(ADP-ribose) polymerase-1 (PARP1) has emerged as a promising anticancer drug target due to its key role in the DNA repair process. Due to its “synthetic lethality" mechanism with BRCA , PARP1 inhibitors are expected to be highly potent and less toxic anticancer agents. In this project, based on the lead structure of selective PARP1 inhibitor discovered in our previous work and the distinct key amino acids in the binding pocket of PARP1 and PARP2, novel compounds with quinazoline-dione or imidazole-piperidinone scaffold were designed by using structure biology method and molecular modeling technique. The inhibitory activities will be evaluated both in vitro and in vivo so as to discover novel highly potent and selective PARP1 inhibitors as anticancer drug candidate. Furthermore, the thermodynamic and kinetic parameters of the potent and selective PARP1 inhibitors will be measured in order to disclose the distinct thermodynamic and kinetic features of various inhibitors. In combination with molecular modeling and computational chemistry, the binding nature in microscopic level of selective PARP1 inhibitors will be explored and used to guide the molecular design and drug candidate selection.

PARP1作为新机制的抗肿瘤药物靶标，基于“合成致死”策略，其抑制剂可选择性阻断BRCA缺陷性肿瘤的DNA损伤修复，是潜在的高效低毒的肿瘤靶向性抗肿瘤药物。依据本课题前期获得的选择性PARP1抑制剂先导结构，采用结构生物学方法和分子模拟技术，利用PARP1和PARP2结合腔中关键差异性氨基酸残基，设计合成喹唑啉二酮和咪唑并哌嗪酮类选择性抑制剂。经酶学、细胞和体内活性评价，获得高活性和高选择性PARP1抑制剂。本课题的另一研究重点是将热力学和动力学用于选择性抑制剂研究，测定代表性化合物与PARP1结合过程中的热力学参数(ΔG，ΔH和ΔS)和动力学参数（kon, koff, τ），结合分子模拟，在深层次上挖掘分子设计内涵，指导分子设计和侯选药物选择。

PARP1作为新机制的抗肿瘤药物靶标，基于“合成致死”策略，其抑制剂可选择性阻断BRCA缺陷性肿瘤的DNA损伤修复，是潜在的高效低毒的肿瘤靶向性抗肿瘤药物。依据本课题前期获得的选择性PARP1抑制剂先导结构，设计合成了喹唑啉二酮和苯并咪唑类PARP1抑制剂150余个。获得了对PARP1抑制活性在纳摩尔水平的化合物近20个，对PARP1具有显著选择性的化合物7个，其中对PARP1具有高活性和选择性的候选化合物2个。采用结构生物学方法，获得了.5个小分子抑制剂与PARP1复合物的晶体结构，揭示了化合物的结合模式，为进一步结构优化提供了结构基础。测定了候选化合物C-7和C-8的结合热力学和动力学特征，在热力学特征方面，与PARP1的结合为焓驱动，与PARP2的结合为焓驱动和熵驱动相结合；在动力学特征方面，与PARP1复合物的解离速度显著低于与PARP2复合物的解离。因此，候选化合物不仅在酶学水平活性测定中，对PARP1具有选择性，而且，候选化合物在动力学结合方面，对PARP1也表现出选择性，这为揭示候选化合物的药效学基础提供了依据。体内药效学表明，候选化合物单药对BRCA1突变的乳腺癌（MDA-MB-436）具有显著的抑制活性（TGI > 90%），与TMZ合用，对原位脑胶质母细胞瘤（U87MG）具有显著的抑制活性（TGI > 85%）。.本项目的实施，为在深层次上挖掘分子设计的内涵，提供了思路和基础，为开发PARP1选择性小分子抑制剂成为抗肿瘤药物，提供了重要的研究思路，奠定了重要的物质基础。