Treatment for neuropathic pain targeting selective inhibition of MEK

描述（由申请人提供）：由慢性炎症和神经系统损伤引起的神经性疼痛特别难以用目前可用的药物治疗。神经性疼痛相关治疗每年给社会造成的额外财务成本估计为160亿美元，而在收入损失和相关的不可估量的人类痛苦方面则要多得多。显然需要一种新的基于机制的神经性疼痛治疗方法。丝裂原活化蛋白激酶（MAPK）是细胞内信号转导分子，在将细胞外事件转导为细胞反应中起关键作用。据报道，背根神经节（DRG）中的ERK1/2及其上游MAPK激酶（MEK1/2）在介导神经性疼痛损伤的信号级联中发挥作用。我们希望验证工作假设：选择性抑制MEK1/2在背根神经节将抑制神经性疼痛。通过三个特定的目的，我们提出研究小分子和表达显性阴性MEK1的病毒载体对MEK1/2的抑制作为一种基于机制的治疗神经性疼痛的方法。该研究包括评估槲皮素的抗伤害性作用，槲皮素是一种小分子黄酮醇化合物，通过与ATP结合口袋重叠的MEK区域结合来抑制MEK1/2，进一步高通量寻找其他具有抗伤害性特性的新型小分子MEK1/2抑制剂，通过硅对接引导的合理化学修饰小分子，并使用AAV2/8-DN-MEK1选择性抑制DRG中的这种信号传导。我们采用最先进的行为学方法对三种啮齿类动物疼痛模型进行体内分析，这些模型具有强烈的炎症（爪垫注射福尔马林）、神经性（神经损伤）或混合性（慢性收缩损伤）病因。传统的疼痛评估（热痛觉过敏和机械异常性痛）以及自发性疼痛的行为分析（负重测试和条件位置偏好）将被采用。提出了一种铅类黄酮醇分子的合理化学修饰，广泛使用配体与MEK的硅对接，以结合自由能作为配体亲和力的衡量标准。研究团队由具有神经科学/疼痛研究，疼痛行为分析和化学合成专业知识的高级研究员组成，共同提供执行该项目所需的所有技能。

DESCRIPTION (provided by applicant): Neuropathic pain resulting from chronic inflammation and injury to the nervous system is particularly difficult to treat with the currently available drg armamentarium. Annual excess financial cost to the society resulting from neuropathic pain-related treatment is estimated to be $16 billion with much more in terms of lost revenue and associated immeasurable human suffering. A novel mechanism-based treatment for neuropathic pain is clearly needed. Mitogen activated protein kinases (MAPK) are intracellular signal transducing molecules that play a critical role in transducing extracellular events to cellular responses. ERK1/2 and its upstream MAPK kinases (MEK1/2) in the dorsal root ganglion (DRG) have been reported to play a role in the signaling cascade mediating injury to neuropathic pain. We wish to test the working hypothesis that: Selective inhibition of MEK1/2 in the dorsal root ganglion will suppress neuropathic pain. Through 3 specific aims, we propose to investigate inhibition of MEK1/2 by small molecules and a viral vector expressing a dominant-negative MEK1 as a mechanism-based treatment for neuropathic pain. The study involves assessment of anti-nociceptive effects of quercetin, a small molecule flavonol compound found to inhibit MEK1/2 by binding to a region of MEK overlapping the ATP- binding pocket, further high throughput search for other novel small molecule MEK1/2 inhibitor with anti-nociceptive properties, modification of the small molecule through in silico docking-guided rational chemistry, and the use of AAV2/8-DN-MEK1 to selectively inhibit this signaling in the DRG. We employ state of art behavioral methods for in vivo analysis of effectiveness against three rodent pain models with a strong inflammatory (paw pad formalin injection), neuropathic (spared nerve injury), or mixed (chronic constriction injury) etiology. Traditional assessment of pain (thermal hyperalgesia and mechanical allodynia) as well as behavioral assays for spontaneous pain (weight bearing test and conditional place preference) will be employed. Rational chemical modification of a lead flavonol molecule with extensive use of in silico docking of ligands to MEK guided by the free-energy of binding as a measure of ligand affinity is proposed. The research team consists of senior investigators with expertise in neuroscience/pain research, behavior assay of pain, and chemical synthesis, together providing all the necessary skills to execute this project.