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中具有重要作用，其功能障碍与许多疾病有关。氯离子通道功能失调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，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活化氯离子通道（CaCCs），如TMEM16A，被认为是人类疾病的药物靶点。抑制CaCCs已被认为是治疗高血压、疼痛、腹泻和粘液分泌过多的一种方法。自我们首次提交该拨款以来，TMEM16a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者。此外，最近的证据表明TMEM16a表达与前列腺癌和胰腺癌的增殖有关。在本文中，我们将系统地探索模块化2-氨基-4-芳基噻唑支架对TMEM16A（第一个表征的CaCC）的抑制效果。本研究的主要假设是：(a) 2-氨基-4-芳基噻唑的分子结构可以在几个位置进行修饰，从而改变与TMEM16A的相互作用，从而提高抑制效力；(b)给定TMEM16a调节剂库，可以创建抑制剂的计算药效团模型，这将有助于进一步优化，也可以作为虚拟筛选的模板；(c)结合模式具有特异性，可以通过同源性建模进行预测，并通过光亲和标记进行确认。这个项目的成功完成将填补

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.