TFCP2刺激YAP与转录因子结合促进肝癌发生发展机制研究

YAP is overexpressed and plays important roles in liver cancer. The function of YAP in promotion of tumorigenesis replies on its interaction with transcription factors. However, whether there exists cooperate proteins that promote interactions between YAP and its transcription factors remains unclear. Our lab has uncovered that YAP is regulated by a complex network in liver cancer cells. Via mass spectrometric (MS) experiments, we also found TFCP2 can be detected in the immune-precipitates that pulled down by anti-YAP antibodies and antibodies against different YAP-dependent transcription factors respectively, suggesting TFCP2 may act as a cooperate protein that is critical for the interactions between YAP and its transcription factors. In this project, we will perform in vitro cell-based, in vivo mouse-based experiments and test clinical liver cancer samples to reveal whether and how TFCP2 promotes liver tumorigenesis through stimulating interactions between YAP and its transcription factors, thereby; provides enough evidences that TCFP2 can be regarded as a potential therapeutic target for the treatment of YAP-dependent liver cancer.

肝癌内YAP表达上调且与肿瘤的发生发展密切相关，而YAP的致瘤作用主要依赖于其相互作用的转录因子，但是否存在协同蛋白促进YAP与其互作转录因子间的相互作用尚不明确。申请人团队已发表研究证明肝癌细胞内存在复杂的调控YAP网络。前期利用质谱技术我们还发现YAP和其多个互作转录因子的免疫沉淀产物中均能检测到TFCP2，提示TFCP2可能是促进YAP与其互作转录因子相互作用的协同蛋白。本课题拟利用体外细胞实验、体内小鼠实验和临床肝癌标本检测三个层面探索TFCP2是否可通过刺激YAP与其互作转录因子结合促进肝癌发生发展并试图揭示相关的分子机制，为临床明确TFCP2可否成为治疗YAP依赖性肝癌的潜在靶位点提供理论依据。

YAP是一种转录共因子其促癌作用已普遍得到认可，但YAP可被Hippo抑癌通路以磷酸化的形式抑制。YAP必需通过与其他蛋白相互作用才能发挥调控下游基因表达的作用，然而此类YAP互作蛋白及所涉及的信号网络和促癌分子机制尚不清楚。在本项目资助下，课题组发现TFCP2与YAP可相互作用促进和维持肝癌细胞恶性表型，并以YAP/TFCP2为突破口进一步发掘其相关信号网络、表达调控机制及存在转化意义的切入点。课题组利用各种组学、体内体外实验手段和临床标本获得了以下成果：1）发现YAP与TFCP2相互作用的分子结构基础、共调控的原癌基因及依赖的含有(G/A)N2(S/G)N5P基序的转录因子；2）发现YAP Thr241位点可被O-糖基化并抵抗Hippo通路对YAP的磷酸化抑制，除YAP外高糖还可通过O-糖基化转录因子YY1和APA1发挥促癌作用；3）阐述了YAP受抑后增加铁死亡敏感性分子机制，并一定程度揭示了肝癌细胞内调控铁死亡的转录调控网络是依赖于HNF4A与HIC1间的平衡实现的；4）揭示了与YAP及TFCP2相关的蛋白和RNA包括CCT3、RRM2及circ104075可作为潜在肝癌血清标志物，联合其他经典及现存指标可同时提高诊断肝癌的灵敏度和特异度； 5）发现克罗索酸和Sirt1可通过促进泛素E3连接酶βTrCP同时抑制YAP与TFCP2发挥抑肝癌作用。相关成果发表于Cell Rep、Nat Commun、Redox Biol、Cell Death Dis等刊物，受资助论文总IF为70.63。项目负责人以此为基础获得国家自然科学基金优秀青年项目和面上项目各1项。本项目以蛋白－蛋白相互作用为线索一定程度阐明了肝癌相关促癌信号网络并发现了具有转化意义的新型肝癌血清学指标，这些成果对进一步以其他互作蛋白为基础阐明与肝癌发生发展密切相关的其他信号调控网络具有借鉴意义。