(PQ9) A novel mechanism of paclitaxel-induced peripheral neuropathy and potential treatment

项目摘要 紫杉醇诱导的周围神经病变（PIPN）和相关的神经性疼痛是最常见的， 接受紫杉醇输注的癌症患者经历的严重不良反应， 活动，从而生活质量，有时迫使暂停治疗， 生存然而，PIPN的发病机制尚不清楚，这阻碍了PIPN的治疗。 为这种并发症开发有效的治疗方法。拟议的研究试图确定分子 PIPN的潜在机制，以及预防PIPN发展的潜在治疗靶点， 神经性疼痛过度的神经元兴奋是PIPN的主要来源。我们的初步数据显示 初级感觉神经元的过度兴奋可能是由于紫杉醇诱导的抑制 KCNQ/Kv 7通道，其在感觉神经元和轴突中丰富。瑞替加滨，一种FDA批准的 一种打开KCNQ/Kv 7通道的药物，可能是一种合理的治疗方法，可以减少紫杉醇诱导的 病理和症状。我们假设紫杉醇诱导周围神经病变， 慢性疼痛通过抑制KCNQ/Kv 7通道和兴奋初级感觉神经元， 因此，在化疗剂输注期间激活KCNQ/Kv 7通道可以防止 PIPN的发展。在这个项目中，我们将在成年无肿瘤大鼠或小鼠中生产PIPN，并利用 免疫组织化学，电生理学，电子显微镜和行为测试技术，以测试 三个重要的预测：1）Paclitaxel通过抑制KCNQ/Kv 7通道兴奋初级感觉神经元。 紫杉醇对KCNQ 2/3过表达的CHO细胞系中KCNQ电流的诱导作用，以及 其对来自幼稚大鼠的DRG神经元的作用（KCNQ电流和膜电位），Kcnq 2fl/fl//Pax 3-Cre， Kcnq 3-/-及其同窝对照小鼠将进行电生理学评估（体外记录）; 2） 紫杉醇通过抑制KCNQ/Kv 7通道诱导周围神经病变和慢性疼痛。XE-991，a 选择性KCNQ/Kv 7通道阻断剂，将被递送至幼稚大鼠，以观察XE-991是否可以模拟PIPN 和慢性疼痛。KCNQ/Kv 7通道在PIPN中的作用将通过暴露以下参数进行评估： Kcnq 2fl/fl//Pax 3-Cre、Kcnq 3-/-及其同窝对照小鼠对紫杉醇的耐受性。疼痛相关行为， 形态学改变（脊髓中的神经胶质增生，皮肤中的IENF，DRG神经元中的ROS，线粒体和 将评估神经切片中的微管）和神经元兴奋性; 3）将瑞替加滨与 紫杉醇可以预防周围神经病变和神经性疼痛的发展。瑞替加宾将是 在暴露于紫杉醇期间给予大鼠。DRG神经元的兴奋性、脊髓胶质增生、IENF 表皮和疼痛相关的行为将被测量。最后，乳腺癌的化疗敏感性 在瑞替加滨存在下评估肿瘤对紫杉醇的耐受性。这些研究可能会导致更好的 了解PIPN的原因以及描绘治疗发展的新靶点。

Project summary Paclitaxel-induced peripheral neuropathy (PIPN) and associated neuropathic pain is the most common and serious adverse effect experienced by cancer patients accepted paclitaxel infusion, which adversely affects daily activities and thereby quality of life, and sometimes forces the suspension of treatment, negatively impacting survival. However, mechanisms underlying the pathogenesis of PIPN are uncertain, which hinders the development of effective therapies for this comorbidity. The proposed studies attempt to identify molecular mechanisms underlying PIPN, as well as a potential therapeutic target to prevent the development of PIPN and neuropathic pain. Excessive neuronal excitation is a primary source of PIPN. Our preliminary data indicate that the hyperexcitability of primary sensory neurons might result from paclitaxel-induced inhibition of KCNQ/Kv7 channels, which are abundant in sensory neurons and axons. Retigabine, an FDA-approved drug that opens KCNQ/Kv7 channels, could be a plausible treatment to reduce paclitaxel-induced pathology and symptoms. We hypothesize that paclitaxel induces peripheral neuropathy and chronic pain by inhibiting KCNQ/Kv7 channels and exciting primary sensory neurons, activating KCNQ/Kv7 channels during chemotherapeutic agent infusion may thus prevent the development of PIPN. In this project, we will produce PIPN in adult, tumor-free rats or mice, and utilize techniques of immunohistochemistry, electrophysiology, electron microscopy, and behavioral testing to test three important predictions: 1) Paclitaxel excites primary sensory neurons by inhibiting KCNQ/Kv7 channels. Paclitaxel-induced effects on KCNQ currents in CHO cell lines in which KCNQ2/3 are overexpressed, as well as its effects (KCNQ currents and membrane potential) on DRG neurons from naïve rats, Kcnq2fl/fl//Pax3-Cre, Kcnq3-/-, and their littermate control mice will be assessed electrophysiologically (in vitro recording); 2) Paclitaxel induces peripheral neuropathy and chronic pain by inhibiting KCNQ/Kv7 channels. XE-991, a selective KCNQ/Kv7 channel blocker, will be delivered to naïve rats to see whether XE-991 can simulate PIPN and chronic pain. The role of KCNQ/Kv7 channels in PIPN will then be evaluated by exposing of Kcnq2fl/fl//Pax3-Cre, Kcnq3-/-, and their littermate control mice to paclitaxel. Pain-related behavior, morphological alterations (gliosis in the spinal cord, IENF in the skin, ROS in DRG neurons, mitochondria and microtubules in nerve sections), and neuronal excitability will be assessed; 3) Combining retigabine with paclitaxel can prevent the development of peripheral neuropathy and neuropathic pain. Retigabine will be given to rats during the exposure to paclitaxel. The excitability of DRG neurons, gliosis in spinal cord, IENF in the epidermis, and pain-related behaviors will be measured. Finally, the chemosensitivity of a breast cancer tumor to paclitaxel will be assessed in the presence of retigabine. These studies may lead both to a better understanding of the causes of PIPN as well as delineate novel targets for therapeutic development.