四跨膜蛋白TSPAN5在肝癌转移中作用及其分子机制

Hepatocellular carcinoma (HCC) has heavily affected human health. No effective treatments are available at present for advanced stages of HCC. Sorafenib as a molecular targeted therapeutic drug has brought new hope to patients with HCC. TSPAN5 is a member of tetraspanins superfamily，some of which have been shown to be involved in cell proliferation and adhesion, tumor invasion and metastasis. However, the role of TSPAN5 in HCC growth and metastasis is unknown. In our pilot studies, we have found for the first time that the expression of TSPAN5 in HCC is significantly down-regulated compared to that in adjacent liver tissue. The migration of HCC cells was significantly inhibited by TSPAN5 in vitro and in vivo, suggesting that TSPAN5 may be important for HCC metastasis as a new HCC suppressor. However, how TSPAN5 suppresses HCC metastasis is unknown. In this project, we are going to investigate the function and molecular mechanism of TSPAN5 in inhibition of the HCC metastasis by means of the modern molecular and cellular technology, proteomics analysis technology, in vitro cell culture technology and in vivo animal xenograft models, as well as the clinical HCC specimens and clinical data. We aim to elucidate the mechanism of TSPAN5 in liver metastasis and to identify novel molecules and molecular pathways for development of new targeted therapeutics against advanced HCC.

肝癌严重威害人类健康，对进展期肝癌目前尚无有效的治疗方法，索拉非尼作为分子靶向抗癌药物给肝癌患者带来了新的希望。TSPAN5属于四跨膜蛋白超家族，已知该家族某些成员可参与细胞的增殖粘附和肿瘤的侵袭转移。但TSPAN5是否参与肿瘤的发生发展及转移目前知之甚少。我们最新研究发现，TSPAN5低表达于肝癌组织而高表达于癌旁正常组织；在体内外实验中能抑制肝癌细胞的迁移能力，提示该分子可能是一个新的抑癌因子。然而，TSPAN5抑制肝癌转移的生化基础及分子机制目前全然未知。因此，本项目在我们前期研究的基础上，拟采用现代分子和细胞生物学方法、基因组学和蛋白质组学分析技术、细胞体外培养技术和动物体内模型构建等方法，结合临床肝癌标本和相关资料，对TSPAN5在肝癌转移中的作用及分子调控机制进行系统研究，旨在阐明TSPAN5在肝癌中的抑癌机制，为深入了解肝癌细胞转移机制、研发新的靶向治疗提供新思路。

肝癌严重威害人体健康，尤其是进展期肝癌目前尚无对其有效的治疗方法，索拉非尼、乐伐替尼或阿替利珠单抗联合贝伐单抗等系统靶向治疗给肝癌患者带来新的希望。肝癌发病机制复杂，特别是对肝癌转移机制，目前知之甚少。TSPAN5属于四跨膜蛋白超家族，已知该家族某些成员可参与细胞的增殖粘附和肿瘤侵袭转移。但TSPAN5是否参与肝癌转移目前一无所知，本课题对此开展了系统研究。本课题首先从肝癌临床标本和相关资料出发，结合肝癌TCGA数据库生信分析，发现TSPAN5高表达于肝癌组织，与癌细胞入侵深度和血管入侵、临床分期和患者的总体生存时间显著相关；利用慢病毒转染方法上调或下掉TSPAN5在不同肝癌细胞系中的表达，发现TSPAN5显著增强肝癌细胞体外迁移能力和体内肝、肺转移能力；深入分子机制研究发现，TSPAN5可通过与ADAM10结合，促进后者的成熟和在S2位点酶切Notch活性，增强伽马分泌酶在S3位点剪切Notch1蛋白，从而激活Notch1信号通路，增强肝癌细胞的EMT转化和细胞内骨架蛋白重排，从而促进癌细胞迁移和转移。进一步利用肝癌TCGA数据库进行生信分析，发现上述作用分子机制通路上的关键接点分子变化全部出现在肝癌临床肿瘤标本中，从而在肝癌临床肿瘤组织中充分验证了上述的实验发现。本研究发现了TSPAN5促进肝癌转移，阐明了其促进转移的分子机制，为深入解析肝癌细胞转移机制全貌、研发靶向治疗新靶点提供了新思路新切入点。