Targeting Mek/Erk Signaling in the Treatment of Mitral Valve Prolapse

摘要 二尖瓣脱垂(MVP)是最常见的心脏瓣膜疾病之一，每40人中就有1人患病。 人类和大约70%的小型犬只。目前尚无有效的非手术治疗MVP和 由于对其根本原因的不完全了解，治疗努力受到了阻碍。近期 我们小组的研究描述了非综合征MVP的遗传基础，并提供了新的见解 转化为疾病背后的分子过程。我们已经使用这种遗传信息来识别可用药 可以为人类提供非手术选择的靶点。特别是，我们已经确定了MEK/ERK 作为主要致病途径的通路和MEK/Erk的长时间高激活驱动疾病 进展和严重程度。激活MEK/Erk通路导致细胞增殖增加，异常 基质金属肽酶(MMPs)的分化和产生。因此，我们假设 对MEK/Erk活性的药理阻断将充分阻止疾病途径和 保持瓣膜处于亚临床状态。这一假设将通过筛选小说和FDA来验证- 已批准的体外(AIM 1)和体内(AIM 2)丝裂原活化蛋白激酶(MEK1)抑制剂。目标1 该提案涉及使用犬MVP和人二尖瓣进行MEK1抑制剂的体外筛选 间质细胞，以及使用非激活的MEK1蛋白执行酶动力学。MEK1是一种 MEK/Erk信号通路中有吸引力的治疗靶点。MEK1抑制剂耐受性良好，FDA- 被批准用于黑色素瘤、非小细胞肺癌(NSCLC)和结直肠癌(CRC)；然而，每 FDA批准的和正在进行的临床试验中的单一MEK1抑制剂与主要细胞色素相互作用和/或遭受 从有害的偏离目标的副作用。我们的团队已经发现了新型的、高选择性的MEK1抑制剂 在硅胶中表现出出色的对接分数，并且不抑制主要细胞色素。因此，在目标1中，我们将测试 假设使用计算机辅助药物设计可以开发出更好的MEK1抑制剂。在目标2中，我们 将评估MEK1药物对小鼠和犬MVP患者的疗效。在实验1中，我们将 对Dzip1S24R/+小鼠同时应用新型和FDA批准的MEK1抑制剂；一种疾病模型 人类MVP的表象。读数将包括：从鼠标获得的功能测量 超声心动图；瓣膜体积的量化；组织病理学和RNA测序。在实验2中，我们 计划用一项双盲、安慰剂对照的临床试验来验证我们的假设，试验对象为40只B1期的狗 双臂MVP(安慰剂或曲美替尼)。读数将包括超声心动图，完整的血细胞计数， 血清化学、NT-ProBNP和高敏心肌肌钙蛋白(hs-cTnI)。这项研究的结果可能 作为为人类MVP患者开发第一个非手术治疗的垫脚石。在……里面 除了更好地了解MVP和潜在的治疗方法外，该奖学金还将 为我提供尖端技术方面的培训，以支持我作为内科科学家的发展。

ABSTRACT Mitral valve prolapse (MVP) is one of the most common forms of cardiac valve disease, affecting 1 in 40 humans and ~70% of small breed dogs. There are no effective nonsurgical treatments for MVP and therapeutic efforts have been hindered due to an incomplete understanding of its fundamental causes. Recent studies by our group have described the genetic basis for non-syndromic MVP and have provided new insights into molecular processes that underlie the disease. We have used this genetic information to identify druggable targets that can provide a non-surgical option for humans. In particular, we have identified the Mek/Erk pathway as the major disease initiating pathway and prolonged hyperactivation of Mek/Erk drives disease progression and severity. Activation of the Mek/Erk pathway leads to increased proliferation, aberrant differentiation, and production of matrix metallopeptidases (MMPs). Thus, we hypothesize that pharmacological blockade of Mek/Erk activities will sufficiently arrest the disease pathway and maintain the valves in a sub-clinical condition. This hypothesis will be tested by screening novel and FDA- approved mitogen-activated protein kinase kinase (MEK1) inhibitors in vitro (Aim 1) and in vivo (Aim 2). Aim 1 of this proposal involves an in vitro screen of MEK1 inhibitors using canine MVP and human mitral valve interstitial cells, as well as performing enzyme kinetics using non-activated MEK1 protein. MEK1 is an attractive therapeutic target within the Mek/Erk signaling pathway. MEK1 inhibitors are well-tolerated and FDA- approved for melanoma, non-small cell lung cancer (NSCLC), and colorectal cancer (CRC); however, every single MEK1 inhibitor, both FDA-approved and in clinical trials, interacts with major cytochromes and/or suffers from deleterious off-target side-effects. Our group has identified novel, highly selective, MEK1 inhibitors that exhibit exceptional docking scores in silico and do not inhibit major cytochromes. Thus, in Aim 1 we will test the hypothesis that superior MEK1 inhibitors can be developed using computer-aided drug design. In Aim 2, we will assess the efficacy of MEK1 drug treatment in mouse and canine MVP patients. In experiment 1, we will administer both novel and FDA-approved MEK1 inhibitors to Dzip1S24R/+ mice; a disease model that phenocopies human MVP. Readouts will include: functional measurements obtained from mouse echocardiography; quantification of valve volume; histopathology, and RNA-sequencing. In experiment 2, we plan to test our hypothesis with a double-blinded, placebo-controlled clinical trial with 40 dogs with stage B1 MVP in each arm (placebo or trametinib). Readouts will include echocardiography, complete blood count, serum chemistry, NT-proBNP, and high sensitivity cardiac troponin (hs-cTnI). Results from this study may serve as a stepping stone towards developing the first non-surgical treatment for human patients with MVP. In addition to developing a better understand of MVP and potential therapeutic approaches, this fellowship will provide me with training in cutting-edge techniques that will support my development as a physician scientist.