CapG在鼻咽癌微环境与鼻咽癌细胞相互作用中的功能及分子网络研究

The Tumor and its Microenvironment is a functional whole. Gelsolin-like actin-capping protein (CapG), as a member of the gelsolin/villin family of actin-regulatory proteins, is achieved by proteomics tools combining laser capture microdissection from nasopharyngeal carcinoma (NPC) mesenchyme. Higher expressed CapG is found associated with more advance clinical stages and poorer histologic grading in NPC, so it is suggested that CapG plays a key role in NPC carcinogenesis. Based on our previous achievement, this study plans to establish two CapG high expressed mesenchymal cell lines, tumor associated fibroblasts (TAF) and tumor associated macrophages (TAM) to analyze the interaction process between TAF/TAM and NPC cells and how CapG works. Cell co-culture tools will be adopted. Quantitative proteomics tools combined with iTRAQ will be used to search the proteomic alternation in culture medium and signaling networks will be set up. This study could contribute to clarify the molecular mechanism and function of CapG in NPC carcinogenesis. Additionally, it probes into the interaction between tumor microenvironment and tumor cells as a first step that provides theory evidence for NPC targeting therapy at microenvironment level.

肿瘤微环境和肿瘤细胞是密不可分的功能整体。CapG蛋白是我们通过激光显微切割结合蛋白质组学技术筛选到的鼻咽癌微环境的间质蛋白，发现CapG高表达的鼻咽癌组织表现更晚的临床分期和更差的组织学类型，CapG的表达可能与鼻咽癌的发生、发展有关。本研究拟在前期研究的基础上，建立CapG高表达的肿瘤微环境的肿瘤相关成纤维细胞（TAF）和肿瘤相关巨噬细胞(TAM)，采用细胞共培养技术观察TAF和TAM与鼻咽癌细胞的相互作用及CapG在这一过程中的功能，应用iTRAQ定量蛋白质组学技术分析上清分泌蛋白质的变化，建立分子网络。本项目不仅有助于阐明CapG在鼻咽癌发生发展的作用及分子机理，而且能初步探讨肿瘤微环境和肿瘤细胞的相互作用，为从肿瘤微环境水平鼻咽癌靶向治疗提供理论依据。

CapG的全称是capping protein (actin filament), gelsolin-like/Macrophage-capping protein，通过调节细胞内actin filaments对细胞骨架进行塑形。这个39 kDa的蛋白质在胞浆和胞质均存在，已有报道capG通过依赖Ca2+- 和PIP2从而对actin的末端“加帽”来调节actin的长度，其核内段被推测能促进体外细胞侵袭。但尚未见capG在鼻咽癌细胞中的功能及机制研究，本项目拟从功能和机制两方面对capG在鼻咽癌的作用进行研究。研究发现capG在鼻咽癌组织及细胞株中普遍高表达，通过RNA干扰降低capG在鼻咽癌细胞株中的表达，发现对细胞增殖无影响，而细胞体外迁移和侵袭功能减弱。对其侵袭机制研究是从两种细胞运动方式及信号通路着手（amoeboid mode和mesenchymal mode），检测参与mesenchymal mode的下游因子WAVE2的表达发现在capG干扰前后无变化，检测发现参与amoeboid mode的RhoA activity (GTP RhoA / Total RhoA)活性下降。目前研究表明下调capG能抑制鼻咽癌细胞体外侵袭能力，可能通过RhoA途径参与作用。