Investigating YAP1 control of differentiation and metabolism in Hepatoblastoma

项目摘要 肝母细胞瘤（HB）是最常见的小儿原发性肝脏肿瘤，影响婴儿至5岁的儿童 年龄。手术切除和辅助化疗挽救了许多年轻人的生命。然而，五年 存活率保持在70%，对于不能切除肿瘤的儿童更差。满足临床需求 HB靶向治疗需要更好地了解HB肿瘤的形成和维持。的 转录辅助调节因子YAP 1在79%的HB病例中过度激活，最近的研究表明YAP 1 和Wnt/β-catenin途径共同作用以引发HB肿瘤。但是，YAP 1是否需要维持HB 肿瘤发生用强力霉素诱导的HB-驱动的条件小鼠模型的初步研究 高活性YAP 1 S127 A和组成型活性β-catenin-提示YAP 1在肿瘤中是必需的 上维护在多西环素存在下，YAP 1表达，小鼠发展为HB肿瘤; 强力霉素关闭YAP 1，导致10周内>90%的肿瘤消退。转录分析 揭示了肝细胞分化因子和肝代谢基因在肿瘤消退中被诱导。 这项计划的目的是了解YAP 1如何失调肝细胞分化和重编程 肝细胞代谢使用HB的条件性小鼠模型，Aim 1将研究YAP 1如何调节 关键的肝细胞分化因子-HNF 4a和FoxA 2-维持HB肿瘤发生。基因检测将 用于确定HNF 4a和FoxA 2是否是促进肿瘤消退所必需的或足够的， 分化将使用基因组和生物化学方法来评估YAP 1 - 100的结合和亲和力。 TEAD与HNF 4a和FoxA 2基因的复合物。Aim 1的结果将提供对YAP 1如何影响 分化状态，并可能有重要的预后意义的HB患者。目标2将研究如何 YAP 1通过重编程肝细胞代谢维持肿瘤发生。糖酵解酶活性 丙酮酸激酶M2（Pkm 2）将在YAP 1依赖性肿瘤中和肿瘤消退期间进行测量， 条件性HB小鼠。RNA干扰将用于确定Pkm 2是否是YAP 1依赖性 肿瘤维持这一目的将研究以前未表征的YAP 1和PKm 2对肿瘤的调控作用。 新陈代谢.这项研究的发现将为深入了解YAP 1在HB肿瘤发生中的机制提供帮助， 可能定义新的预后因素和药物靶点，以治疗患有HB的儿童。

Project Summary Hepatoblastoma (HB), the most common pediatric primary liver tumor, affects children from infancy to five years of age. Surgical resection with adjuvant chemotherapy has saved many young lives. However, the five-year survival rate remains at 70%, and is worse for children with unresectable tumors. Meeting the clinical need for HB-targeted therapies requires a better understanding of how HB tumors are formed and maintained. The transcriptional co-regulator YAP1 is hyper-activated in 79% of HB cases, and recent studies suggest that YAP1 and the Wnt/β-catenin pathway act together to initiate HB tumors. But is YAP1 required to maintain HB tumorigenesis? Preliminary studies using a conditional mouse model of HB—driven by doxycycline-inducible hyperactive YAP1S127A and constitutively-active β-catenin—suggest that YAP1 is essential for tumor maintenance. In the presence of doxycycline, YAP1 is expressed, and mice develop HB tumors; withdrawing doxycycline turns off YAP1, resulting in >90% tumor regression within 10 weeks. Transcriptional analyses revealed that hepatocyte differentiation factors and liver metabolic genes were induced in regressing tumors. The goal of this proposal is to understand how YAP1 dysregulates hepatocyte differentiation and reprograms hepatocyte metabolism. Using a conditional mouse model of HB, Aim 1 will investigate how YAP1 regulates critical hepatocyte differentiation factors—HNF4a and FoxA2—to maintain HB tumorigenesis. Genetic tests will be used to determine whether HNF4a and FoxA2 are necessary or sufficient to promote tumor regression and differentiation. Genomic and biochemical approaches will be used to assess binding and affinity of the YAP1- TEAD complex to HNF4a and FoxA2 genes. Results from Aim 1 will provide insight into how YAP1 affects differentiation status and may have important prognostic implications for HB patients. Aim 2 will investigate how YAP1 maintains tumorigenesis by reprogramming hepatocyte metabolism. The glycolytic enzyme activity of pyruvate kinase M2 (Pkm2) will be measured in YAP1-dependent tumors and during tumor regression in conditional HB mice. RNA interference will be used to determine whether Pkm2 is required for YAP1-dependent tumor maintenance. This aim will examine previously uncharacterized YAP1 and Pkm2 regulation of tumor metabolism. Findings from this study will provide insight into the mechanisms of YAP1 in HB tumorigenesis and may define new prognostic factors and druggable targets to treat children suffering from HB.