NRSF介导的μ阿片受体表达调控参与骨癌痛的机制及相关镇痛策略研究

As one the most common and severe symptoms of cancer patients, bone cancer pain has complex pathophysiologic mechanisms and is resistant to conventional treatment. Analgesic tolerance frequently occurs even with morphine, which is the ‘cornerstone’ of analgesic treatment. Hence it is disruptive to a patient’s quality of life. Recently a great deal of attention has been paid to the effects of neuroimmune response in the pathogenesis of bone cancer pain. In the preliminary experiment, the expression of μ-opioid receptor (MOR) in the DRG was significantly down regulated in the bone sarcoma bearing mice while the expression level of neuron-restrictive silencer factor (NRSF) was significantly elevated. We suppose that with the induction of neuroimmune response, signal pathways such as ERK are activated in the DRG neurons and the transcription of NRSF is up-regulated. Subsequently, the expression of MOR is depressed via epigenetic mechanisms, which are involved in the abnormal pain behaviors observed in bone cancer animals. In this study, the upstream inflammatory mediators modulating the expression of NRSF and the signal transducing pathways will be firstly investigated. Secondly, the epigenetic mechanisms underlying the modulation of MOR by NRSF will be clarified with the methods of chromatin immunoprecipitation (ChIP) and so on. Thirdly, the relation between the expression of NRSF or MOR and morphine tolerance will be examined. Thereafter effective analgesic drugs will be screened and the analgesic mechanisms will be elucidated. This study is of important significance for revealing the pathogenesis of bone cancer pain as well as morphine tolerance clarifying the modulating mechanisms underlying the transcription of MOR gene and screening of new drug targets as well as new strategies for the treatment of bone cancer pain.

骨癌痛是肿瘤患者最常见、最严重的症状之一。其发病机制复杂，即便是镇痛治疗的“基石”吗啡也常发生耐药，给患者的生活质量带来灾难性影响。近年来，神经炎症在骨癌痛发生中的作用受到重视。前期研究中我们发现骨肉瘤小鼠背根神经节(DRG)中μ-型阿片受体(MOR)表达下降，神经元限制性静默因子(NRSF)表达增加。我们推测骨癌痛时神经炎症反应致DRG神经元内ERK等信号通路激活，并上调NRSF表达；随后NRSF经表观遗传学机制抑制MOR的表达，参与了痛行为异常的发生。本项目拟先探寻调控NRSF的上游炎症因子及信号转导通路；再采用染色体免疫共沉淀等方法，阐明NRSF调控MOR表达的表观遗传学机制；并观察NRSF、MOR表达调控与吗啡耐受的相关关系，筛选有效镇痛药物并阐明镇痛机制。本课题对于阐明骨癌痛的发病机理及吗啡耐受的机制，揭示MOR的转录调控体系，探寻治疗骨癌痛的新药物靶点和治疗策略具有重要意义。

骨癌痛是肿瘤患者最常见、最严重的症状之一。其发病机制复杂，即便是镇痛治疗的“基石”吗啡也常发生耐药，给患者的生活质量带来灾难性影响。近年来，神经炎症在骨癌痛发生中的作用受到重视。前期研究中我们发现骨肉瘤小鼠背根神经节(DRG)中μ-型阿片受体(MOR)表达下降，神经元限制性静默因子(NRSF)表达增加。进一步探寻调控NRSF的上游炎症因子及信号转导通路的相关研究发现，骨癌痛时，神经炎症反应释放的IL-6等炎症因子，经由ERK-JNK信号通路，上调DRG神经元内NRSF表达；随后，再采用染色体免疫共沉淀等方法发现，NRSF与MOR启动子区域NRSE位点结合，并经表观遗传学机制抑制MOR的表达改变，参与了吗啡耐受的机制与骨肿瘤模型动物痛行为异常的发生；最后，研究筛选了传统中药提取物的抗炎镇痛作用，发现传统中药银杏叶提取物EGb-761可抑制炎症因子表达，并逆转骨肿瘤小鼠DRG中NRSF表达上调及小鼠痛行为异常和吗啡耐受现象，进一步采用神经元原代培养证实EGb-761可抑制IL-6刺激导致的pERK、pJNK以及AP-1、Sp1的表达增加。本课题对于阐明骨癌痛的发病机理及吗啡耐受的机制，揭示MOR的转录调控体系，探寻治疗骨癌痛的新药物靶点和治疗策略具有重要意义。