Development of inhibitors of the calcium-activated chloride channel TMEM16a

描述（由申请人提供）：氯离子通道在正常人体生理学中具有重要作用，其功能障碍与许多疾病有关。功能失调的氯离子通道的一个重要例子是囊性纤维化跨膜传导调节因子（CFTR）的突变，其导致囊性纤维化（CF），这是最常见的限制生命的遗传疾病之一。另一类氯离子通道是钙激活的氯离子通道（CaCC），例如TMEM 16 A，其被假定为人类疾病的药物靶标。已建议抑制CaCC作为治疗高血压、疼痛、腹泻和粘液产生过量的方法。自我们首次提交该资助以来，TMEM 16 a抑制剂已被实验证明是治疗高血压和哮喘的有希望的候选药物。此外，最近的证据表明TMEM 16 a表达与前列腺癌和胰腺癌的增殖之间存在联系。在该提案中，我们将系统地探索模块化2-氨基-4-芳基噻唑支架的SAR，以确定其抑制TMEM 16 A的功效，TMEM 16 A是第一个表征的CaCC。该建议的中心假设是：（a）2-氨基-4-芳基噻唑的分子结构可以在几个位置被修饰以改变与TMEM 16 A的相互作用，进而提高抑制效力;（B）给定TMEM 16 a调节剂的文库，可以产生抑制剂的计算药效团模型，其将促进进一步优化并且还可以用作虚拟筛选的模板;（c）结合模式是特异性的，并且可以通过同源性建模来预测，并用光亲和标记来确认。该项目的成功完成将填补 CaCC-TMEM 16 A的知识，即基于非常有前途且相对有效的HTS先导支架成功产生新型抑制剂。我们预计这种抑制剂可以优化到纳摩尔范围内，可以用于未来的药物开发研究，也可以有助于对TMEM 16 A作为特定药物靶标和一般CaCC的基本科学理解。在此，我们追求三个具体目标，与2-氨基-4-芳基噻唑支架的系统优化有关：（1）探索2-嘧啶杂环对TMEM 16 A抑制剂效力的影响;（2）探索噻唑缀合的芳基噻唑对TMEM 16 A抑制剂效力的影响。（3）产生TMEM 16 a抑制剂的药效团模型;使用同源建模预测结合模式;和通过光亲和标记确认结合模式。

DESCRIPTION (provided by applicant): Chloride channels have important roles in normal human physiology, and their dysfunction is involved in a number of diseases. An important example of a mis-functioning chloride channel is mutation of the cystic fibrosis transmembrane conductance regulator (CFTR), which causes cystic fibrosis (CF), one of the most common life-limiting genetic diseases. Another class of chloride channels are the calcium-activated chloride channels (CaCCs), such as TMEM16A, which are postulated to be drug targets for human diseases. Inhibition of CaCCs has been suggested as a method to treat hypertension, pain, diarrhea, and excess mucus production. Since our first submission of this grant, TMEM16a inhibitors have been experimentally shown to be promising candidates for the treatment of hypertension and asthma. Furthermore, recent evidence suggests a link between TMEM16a expression and the proliferation of prostate and pancreatic cancer. In this proposal, we will systematically explore the SAR of the modular 2-amino-4-arylthiazole scaffold for its efficacy to inhibit the TMEM16A, the first characterized CaCC. The central hypotheses of this proposal are: (a) the molecular structure of the 2-amino-4-arylthiazoles can be modified at several positions to alter the interactions with TMEM16A, in turn improving inhibitory potency; (b) given libraries of TMEM16a modulators, computational pharmacophore models for inhibitors can be created which will facilitate further optimization and can also serve as a template for virtual screening; (c) the binding mode is specific and can be predicted through homology modeling and confirmed with photoaffinity labeling. Successful completion of this project will fill a gap in the knowledge of CaCC-TMEM16A, namely the successful generation of novel inhibitors based on a very promising, and relatively potent HTS lead scaffold. Such inhibitors, which we anticipate can be optimized into the nanomolar range, could serve in future drug development studies, and could also contribute to the basic scientific understanding of TMEM16A as a drug target in specific, and CaCCs in general. Herein, we are pursuing three specific aims, having to do with the systematic optimization of the 2-amino-4- arylthiazole scaffold: (1) explore the effect of the 2-pyrimidine heterocycle on the potency of TMEM16A inhibitors; (2) explore the effect of the thiazole-conjugated aryl (or heteroaryl) ring systems on the potency of TMEM16A inhibitors; generation of a library of "synergistic inhibitors"; (3) generation of pharmacophore models for inhibitors of TMEM16a; prediction of the mode of binding using homology modeling; and confirmation of the binding mode by photoaffinity labeling.