转录因子TEAD4促进结直肠癌淋巴转移的生物学功能与机制研究

Previously, we found that transcription factor TEAD4 is overexpressed, and promotes EMT and distal metastasis in CRC. Clinicopathological analysis also showed that TEAD4 overexpression is positively correlated with lymph node metastasis in CRC, but the function and mechanism of TEAD4 in CRC lymphatic metastasis is unknown. CCBE1-VEGFC axis plays a vital role in development of Lymphatic vessel and lymphangiogenesis during development, however, the role of CCBE1 in tumor lymphatic metastasis need to be explored. Our primary study indicates TEAD4 could promote CRC lymphatic metastasis through enhancing CCBE1 mRNA expression. In this study, we will explore the role of TEAD4, CCBE1 in tumor lymphangiogenesis and lymphatic metastasis by using in vitro human lymphatic endothelial cells and in vivo CRC lymphatic metastasis model. Multiple molecular techniques will be used to show the direct regulation of CCBE1 by TEAD4 and CCBE1 mediates the function of TEAD4 in promoting lymphatic metastasis. Last, we will study the correlation between clinicopathological characteristics and TEAD4, CCBE1, and the prognostic value of CCBE1 in CRC. Our study will reveal the vital role of CCBE1-VEGFC axis in tumor lymphatic metastasis and illustrate the molecular mechanism of TEAD4 in promoting lymphatic metastasis in CRC, providing novel biomarkers and drug targets for diagnosis and treatment of CRC.

前期发现转录因子TEAD4在结直肠癌（CRC）中高表达，促进EMT和远端转移。同时TEAD4高表达与CRC淋巴结转移相关，但TEAD4在CRC淋巴转移中的作用和机制尚不明确。CCBE1-VEGFC是淋巴管发育、生成的重要信号通路，但CCBE1在肿瘤淋巴转移中的作用也不明确。前期研究表明TEAD4可能通过调控CCBE1表达，进而促进CRC淋巴转移。本课题拟：在淋巴内皮细胞体外模型和淋巴转移体内模型中，研究TEAD4、CCBE1在CRC淋巴管生成和淋巴转移中的作用；利用分子生物学技术，研究TEAD4直接调控CCBE1转录表达以及CCBE1介导TEAD4的促CRC淋巴转移的功能；并在CRC样本中检测TEAD4、CCBE1与临床病理资料和预后的相关性。本研究将揭示CCBE1 -VEGFC在肿瘤淋巴转移中的重要作用，阐明TEAD4促进CRC淋巴转移的分子机制，为CRC的临床诊断治疗提供新分子标记物。

胚胎淋巴管发育关键因子CCBE1与淋巴管发育密切相关，但其在肿瘤淋巴管新生以及淋巴结转移中的作用尚不明确。Hippo信号通路失活导致下游转录复合体YAP/TEAD活性增强，与肿瘤发生、转移有着密切关系。既往YAP/TEAD促癌的生物学功能研究聚焦于肿瘤细胞增殖、细胞迁移与侵袭、肿瘤血管新生，YAP/TEAD是否与肿瘤淋巴管新生相关，也未见报道。通过本项目研究，我们发现CCBE1在肠癌细胞和肿瘤成纤维细胞中高表达，与肠癌淋巴结转移和不良预后正相关；肠癌细胞中CCBE1高表达促进VEGFC的酶切成熟，进而促进了淋巴管新生以及淋巴结转移；肠癌细胞以及肿瘤成纤维细胞中TGF-beta通过激活转录因子SMAD2/3，进而抑制CCBE1的基因转录表达，而YAP/TEAD4则激活CCBE1的基因转录表达。本项目揭示了CCBE1-VEGFC信号轴在肿瘤淋巴管新生和淋巴转移中的重要作用，发现了CCBE1基因转录激活/抑制调控机制，阐明了CCBE1在肠癌进展过程中的失调机制，提出了CCBE1的蛋白表达水平是结直肠癌的不良预后分子标记物。