Role of Age in Liver Cancer

描述（由申请人提供）：年龄是肝癌发展的主要风险因素之一，肝癌是世界上第五大常见癌症和第三大癌症相关死亡原因。尽管癌症研究取得了重大进展，但肝癌的早期检测和治疗进展甚微，导致预后不良。在过去的15年里，我的实验室一直在进行研究，以确定衰老改变的关键信号通路，这些通路使肝细胞更容易发生肝癌。这些途径之一是转录因子CCAAT/增强子结合蛋白α C/EBPa在S193处的过度磷酸化。我们已经成功地产生了C/EBPa-S193 D敲入小鼠（S193 D），其模拟与年龄相关的ph-S193同种型的C/EBPa，并发现在S193 D小鼠中，部分肝切除术后的肝增殖被完全抑制。令我们惊讶的是，我们发现S193 D小鼠中肝肿瘤的发展比WT小鼠快得多。此外，我们发现gankyrin特异性地与C/EBPa的S193 D和ph-S193亚型相互作用并降解。本申请的主要假设是Gankyrin的活化和随后的C/EBPa降解是肝癌发展中的关键调节途径。我们最近的研究表明，法尼醇X受体（FXR）及其下游靶点SHP抑制Gankyrin。FXR/SHP的缺失导致Gankyrin的活化，导致C/EBP α的降解和在12-17个月之间的年龄的自发性肝肿瘤的形成。具体目标1将解决FXR/SHP途径抑制gankyrin的机制。为此，我们计划实现以下目标：a）调查单个FXR和SHP KO小鼠是否激活Gankyrin，b）检查新生儿、2个月、6个月和12个月大的FXR/SHP DKO小鼠中Gankyrin的激活，以确定Gankyrin被激活的年龄，B）鉴定参与Gankyrin激活的FXR依赖性转录因子，和d）通过测量从不同年龄的患者获得的人HCC样品中的gankyrin来验证gankyrin- C/EBPa途径的激活。特异性目标2将检查FXR的激活是否抑制肝肿瘤。我们将通过FXR特异性配体GW 4064激活FXR，并检查这种激活是否会降低DEN介导的致癌作用中肝肿瘤的发生率/数量。具体目标3将研究抑制gankrex-C/EBP 1通路是否会防止肝肿瘤形成。我们计划使用以下方法：a）在WT DEN处理的小鼠和FXR/SHP小鼠中通过siRNA抑制gankyrin的表达，并检查这种抑制是否会降低肝肿瘤的发生率/数量，以及B）开发阻断gankyrin与C/EBP 1结合的方法。因此，拟议的研究将为预防肝癌提供新的基于ganklets的方法。 公共卫生相关性：该项目研究肝癌发展的分子基础。尽管癌症研究取得了重大进展，但迫切需要开发新的方法来早期发现和有效管理肝癌。我们将确定肝癌激活Gankyrin和降解肿瘤抑制因子ph-S193 C/EBP 1亚型的机制，旨在为预防肝癌的治疗方法的产生提供基础。

DESCRIPTION (provided by applicant): Age is one of the major risk factors for development of the liver cancer, which is the fifth most common cancer and the third most common cause of cancer related death in the world. Despite significant advances in cancer research, little progress has been made in early detection and treatment of liver cancer leading to poor prognosis. Over the past 15 years, my laboratory has pursued the studies to determine the key signaling pathways that are changed by aging and that make liver cells more susceptible to development of liver cancer. One of these pathways is the hyper-phosphorylation of a transcription factor, CCAAT/Enhancer Binding protein alpha, C/EBPa, at S193. We have successfully generated C/EBPa-S193D knockin mice (S193D) which mimic the age-associated ph-S193 isoform of C/EBPa and found that liver proliferation after partial hepatectomy is completely inhibited in S193D mice. To our surprise, we found that the development of liver tumors in S193D mice occurs much faster than in WT mice. Furthermore, we found that gankyrin specifically interacts with and degrades the S193D and ph-S193 isoforms of C/EBPa. The main hypothesis of the application is that the activation of gankyrin and following degradation of C/EBPa is a key regulatory pathway in development of liver cancer. Our recent studies show that farnesoid X receptor (FXR) and its down-stream target SHP suppress gankyrin. The deletion of FXR/SHP leads to activation of gankyrin resulting in the degradation of C/EBPa and the formation of spontaneous liver tumors at age between 12-17 months. Specific Aim 1 will address mechanisms by which FXR/SHP pathway represses gankyrin. In this aim, we plan to accomplish the following: a) Investigate if single FXR and SHP KO mice activate gankyrin, b) Examine the activation of gankyrin in newborn, 2 mo, 6 mo and 12 mo old FXR/SHP DKO mice in order to determine the age at which gankyrin is activated, c) Identify FXR-dependent transcription factors that are involved in the activation of gankyrin, and d) Verify the activation of gankyrin- C/EBPa pathway by measuring gankyrin in human HCC samples obtained from patients of different ages. Specific Aim 2 will examine if the activation of FXR inhibits liver tumor. We will activate FXR by FXR-specific ligand GW4064 and examine if this activation will reduce the incidence/number of liver tumors in DEN- mediated carcinogenesis. Specific Aim 3 will investigate if the inhibition of gankyrin-C/EBP1 pathway will prevent liver tumor formation. We plan to use the following approaches: a) Inhibit the expression of gankyrin by siRNA in both WT DEN-treated mice and FXR/SHP mice and examine if this inhibition will reduce the incidence/number of liver tumors, and b) Develop approaches to block gankyrin binding to C/EBP1. Thus, the proposed studies will provide novel gankyrin-based approaches for the prevention of liver cancer. PUBLIC HEALTH RELEVANCE: This project investigates molecular basis for the development of cancer in the liver. Despite significant advances in cancer research, there is an urgent need to develop new approaches for the early detection and effective management of liver cancer. We will determine mechanisms by which liver cancer activates gankyrin and degrades tumor suppressor ph-S193 isoform of C/EBP1 with the goal to provide basement for the generation of therapeutic approaches to prevent liver cancer.