肿瘤相关巨噬细胞调控GAP43介导神经生长活动在骨癌痛中的作用及机制研究

骨癌痛(BCP)疼痛剧烈且治疗效果不佳。骨肿瘤局部神经异常生长分化参与癌痛发生。生长相关蛋白43(GAP43)是神经生长标记物。本项目前期研究发现：抑制GAP43可减少神经损伤后异常自发放电并缓解疼痛；BCP患者肿瘤骨GAP43阳性神经纤维增生活跃；BCP大鼠背根节GAP43上调，骨髓腔肿瘤相关巨噬细胞(TAMs)浸润及IL-6表达增加；抑制TAMs可缓解BCP，减少IL-6, PKCγ及GAP43表达；体外实验发现TAMs可促进神经生长及兴奋性增加。因此，我们提出TAMs调控GAP43介导神经生长参与BCP：TAMs分泌IL-6作用于局部神经元，通过PKCγ导致GAP43上调并激活，促进神经生长，神经元兴奋性异常增加并自发放电，导致BCP。我们拟探寻BCP大鼠TAMs表型及功能变化调控局部神经生长分子机制，研究GAP43介导神经生长活动在BCP中的作用，为癌痛治疗及研究寻找潜在靶点。

Bone cancer pain (BCP) is severe and hard to control. Bone cancer induced nerve fiber sprouting and differentiation are involved in cancer pain. Growth associated protein 43 (GAP 43) plays a key role in axonal growth during nerve development and regeneration. In the preliminary study, we found that density of GAP43 positive nerve fibers were obviously increased in the periosteum of the BCP patient; inhibition of GAP43 can significantly relieve the spontaneous neuronal activity and pain after nerve injury. Expression of GAP43 was up-regulated in dorsal root ganglia, and infiltration of tumor-associated macrophages (TAMs) and IL-6 expression was increased in bone marrow cavity of BCP rats. Inhibition of TAMs with trabectedin can alleviate BCP and down-regulated the expression of IL-6, PKCγ and GAP43 in BCP rats. Furthermore, we found that TAMs promoted nerve growth, increased expression of GAP43 and neuronal excitability in vitro. We hypothesize that TAMs regulating GAP43 mediated nerve growth and play a key role in the BCP: TAMs release IL-6 and act on surrounding neuron, which leads to the upregulation and activation of GAP43 through PKCγ, promotes the abnormal nerve growth activity, increases the excitability of neuron, and spontaneous activity, which ultimately result in BCP. In the proposed study, we plan to observe the phenotypic and functional of TAMs, explore molecular mechanisms by which TAMs regulate nerve growth, and study the role of GAP43 mediated nerve growth on neuronal excitability and electrophysiological characteristics in BCP. Our proposed study will help to unveil the mechanism of BCP, and provide potential targets for the treatment.