慢性精神应激通过α7nAchR-PP1γ促进肝细胞肝癌发生发展的机制研究

Recent investigations implicated that chronic psychological stress may affect cancer progression via nicotinic acetylcholine receptor pathway. Our preliminary results showed that α7 nicotinic Acetylcholine Receptor (α7nAchR) was highly expressed in hepatocellular carcinoma (HCC) tissues, and α7nAchR interacted with Protein phosphatase 1γ (PP1γ) using mass spectrum and immunoprecipitation approaches. PP1γ has been recently documented to facilitate TRAF6/NF-κB and Raf/Yap1 pathways. On the basis of these findings, we put forward the hypothesis that Ach-triggered α7nAchR activation may facilitate HCC progression via the modulation of PP1γ-dependent TRAF6/NF-κB and Raf/Yap1 pathways. We aim to first investigate the correlation among α7nAchR, PP1γ, NF-κB p65 and Yap1 expression, as well as the association between their expression with the clinicopathological factors of HCC patients. Next, we will analyze the role of α7nAchR and PP1γ in triggering the activation of TRAF6/NF-κB and Raf/Yap1 pathways. Moreover, we will determine the impact of interference of α7nAchR and PP1γ on TRAF6/NF-κB and Raf/Yap1 pathways and HCC progression using cultured HCC cells. Finally, we will explore the involvement of chronic stress-mediated α7nAchR/PP1γ signaling on HCC development in vivo. Our study may help clarify the mechanism underlying chronic stress-triggered HCC progression, and may provide novel insights into the prevention and clinical therapy of HCC.

近年来的研究发现，慢性精神压力可通过乙酰胆碱（Ach）递质通路影响肿瘤的发生发展。课题组预实验发现α7烟碱型乙酰胆碱受体（α7nAChR）在肝癌组织中高表达，并且发现α7nAChR结合蛋白磷酸酶1（PP1γ）；PP1γ被报道可促进TRAF6/NF-κB和Raf/Yap1通路的激活。基于此，课题组提出假说：Ach-α7nAChR可通过PP1γ介导NF-κB和Yap1活化促进肝细胞肝癌进程。本课题拟首先研究α7nAChR、PP1γ相互作用调节机制；进而明确对下游NF-κB和Yap1通路的影响；并通过干预α7nAChR和PP1γ阐明α7nAChR通过PP1γ促进TRAF6/NF-κB和Raf/Yap1及肝癌进程的机制；最后以裸鼠模型分析慢性精神压力通过α7nAChR/PP1γ通路对肝癌发生发展的调节作用。本研究将有助于阐明长期的精神压力对肝癌发生发展的促进机制，并为相关的临床治疗提供理论依据。

慢性精神压力和外周神经系统对肿瘤进程的影响是近年来肿瘤研究的热点之一。很多研究表明，压力应激可诱导外周神经纤维分泌各类神经递质（去甲肾上腺素、乙酰胆碱、多巴胺和γ-氨基丁酸等）并直接作用于肿瘤细胞，促进肿瘤细胞的增殖、耐药性和转移等恶性表型。但上述机制目前依然有众多的空白之处，涉及的分子转导通路尚不完全清楚。本项目主要研究了副交感神经系统通过分泌乙酰胆碱促进肝癌发生发展的分子机制研究。项目发现乙酰胆碱可以通过激活肿瘤细胞表面的α7烟碱型乙酰胆碱受体（α7nAChR），进而促进α7nAChR通过PP1γ/TRAF6通路活化肿瘤细胞内的NF-kB通路，继而促进细胞周期相关蛋白如PCNA和Cyclin D1等的表达，导致肿瘤细胞增殖加速和干细胞性的明显升高。课题组发现α7nAChR和PP1γ存在直接的结合，干预上述结合可以明显抑制乙酰胆碱和烟碱诱导的肝癌细胞增殖和干细胞性。上述研究表明，慢性精神应激可通过乙酰胆碱通路直接促进肝癌患者的肿瘤恶化进程，为阐明精神压力对肿瘤的影响提供了良好的理论依据。