氯苯甲嗪对顺铂致背根神经节神经元损伤的保护作用及机理研究

Cisplatin is a widely used cancer chemotherapy drug with significant effect for many type of cancer. However, it also induces serious neuropathy in many patients, which becomes one of the major limits for the usage of cisplatin. How to protect neuron from damages induced by cisplatin is a very important project for chemotherapy. Dorsal root ganglion (DRG) neuron is one of peripheral neuron and the major function is collecting signals from sensory neurons and forwarding to center nerves system. It is a major target cell during cisplatin induced neuropathy. Cisplatin can be accumulated in DRG neuron and introduce cross-linking of DNA on both genomic DNA and mitochondrial DNA. These DNA damages led to abnormal in gene expression, mitochondria structure and function, and even degeneration of mitochondria. Cisplatin also causes accumulation of reactive oxidative species (ROS) and leds to oxidative damages. With the accumulation of damages, DRG neuron would show abnormal cellular function, degeneration of axon and may even undergo apoptosis. Meclizine is a widely used anti-nausea drug. In recent researches, meclizine has been reported to be protective for central nervous system in animal model of stroke. It is reported to be working through inhibition of the function of mitochondria, increasing NADH amount thus reducing mitochondrial damages. It has also been found to activate NRF2 signaling, which is a major pathway for cell to eliminate ROS and reduce oxidative damage. However, the downstream signaling of meclizine induced NRF2 signaling in DRG neuron is not reported yet. Till now, the published results on the protective effect of meclizine are limited on central nervous system only, while there’s no report using meclizine to protect neurons in peripheral nervous system, especially in DRG neuron. In this project, we will explore the protective effect of meclizine on DRG neuron from damages induced by cisplatin. We will exam how meclizine could reduce mitochondria damages and maintain normal mitochondrial function after cisplatin treatment and also on understanding how meclizine promotes the NRF2 signaling in DRG neuron and what are the down streaming genes for cell to eliminating ROS and reducing oxidative damage. This work would be a breakthrough in understanding the neuron protective function of meclizine, and would be a great progress for the establishment of using meclizine as an effective treatment for cisplatin induced neuropathy.

顺铂是应用广泛，疗效显著的化疗药物，但也导致严重神经损伤副作用。如何减少顺铂致神经损伤具有重要临床意义。背根神经节(DRG)神经元是汇集感知神经细胞信号并传导至中枢神经的重要神经细胞。临床研究发现DRG神经元是顺铂致神经损伤的主要效应细胞，它可在DRG神经元中积累并损伤基因组和线粒体DNA，造成线粒体结构与功能异常及活性氧自由基的积累，导致线粒体病变，细胞功能失常，神经末梢损伤和凋亡。新近研究发现，氯苯甲嗪可以减少中枢神经损伤，其主要机制为抑制线粒体功能，增加还原型辅酶II以减少线粒体损伤，也可能激活NRF2信号通路而参与减少氧化性损伤,但具体信号机制尚无报道。在已发表的工作中，未见氯苯甲嗪用于外周神经系统，尤其DRG神经元保护的报道。本项目拟研究氯苯甲嗪对于顺铂致DRG神经元损伤的保护作用，明确其对线粒体的保护作用及机制,阐明其减少氧化性损伤的信号通路，从而推动其在神经损伤治疗中的应用

顺铂是应用广泛，疗效显著的化疗药物，但也导致严重神经损伤副作用。如何减少顺铂致神经损伤具有重要临床意义。DRG神经元是顺铂致神经损伤的主要效应细胞，本项研究中，我们系统的探索了氯苯甲嗪对于DRG神经元所受的顺铂损伤的保护作用效果及保护机制。我们首次发现，在顺铂与氯苯甲嗪共处理的DRG神经元与顺铂组相比，细胞的存活率显著上升，神经突触的数目与长度都未受明显破坏。氯苯甲嗪的保护作用首先体现在对线粒体的保护上，氯苯甲嗪共处理组的DRG神经元对比顺铂组线粒体数目，线粒体DNA拷贝数都显著增加，线粒体功能也更接近对照组，体现在线粒体内膜电位以及细胞的氧气消耗速率上。我们进一步阐明了氯苯甲嗪的线粒体保护作用是与磷酸乙醇胺代谢途径协同进行的，以siRNA调节磷酸乙醇胺核心调控蛋白PCYT2可以联合氯苯甲嗪获得更好保护效果。另外通过全转录组RNA测序方法，我们发现氯苯甲嗪可以激活线粒体发生过程中核心信号分子PRC1和PCG1α的表达，增加线粒体的增长速度。同时，我们也发现氯苯甲嗪可以有效减少DRG神经元在顺铂损伤时遭受的DNA损伤，其作用机制体现在细胞内的ROS被氯苯甲嗪有效清除。由于氯苯甲嗪可以帮助DRG神经元维持住胞内NADPH和还原型GSH水平，使其不因为顺铂处理而下降。上述结果不仅证明了氯苯甲嗪可以作为有效保护DRG神经元的药物，也证实了我们提出预测，即氯苯甲嗪可以以多种不同的机制，在不同层面保护DRG神经元，这些保护机制可以与其他通路中的分子协同作用，达到更好的保护作用。本项工作的结果可以有效推动氯苯甲嗪在顺铂及其他因素导致的神经损伤治疗领域的应用。