The RB pathway in liver cancer

肝癌中的RB通路

基本信息

批准号：
8676681
负责人：
JULIEN SAGE
金额：
$ 26.96万
依托单位：
STANFORD UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2006
资助国家：
美国
起止时间：
2006-07-01 至 2017-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8676681
关键词：
Address Adult Aflatoxin B1 Alcohol abuse Alleles Automobile Driving CDK2 gene CDK4 gene Cancer Patient Cancerous Cell Cycle Cell Maintenance Cell division Cells Child Complement Complex Cyclin D1 Cyclin-Dependent Kinase Inhibitor 2A Data Development Diagnosis E2F transcription factors EZH2 gene Employee Strikes Environmental Risk Factor Epigenetic Process Equilibrium Event Exposure to Family Family member Feedback Future Gene Expression Gene Family Genetic Genetic Models Genetic Transcription Goals Growth Heavy Drinking Hepatitis B Hepatitis B Virus Hepatitis C virus Hepatocyte Histology Human Knock-out Knockout Mice Lesion Liver Liver diseases Liver neoplasms Malignant Epithelial Cell Malignant Neoplasms Malignant neoplasm of liver Mediator of activation protein Metabolic Methyltransferase Modeling Molecular Molecular Profiling Mus Mutant Strains Mice Mutation Notch Signaling Pathway Outcome Pathway interactions Patients Phosphotransferases Polycomb Population Primary carcinoma of the liver cells Proliferating Protein Family Proteins Retinoblastoma Risk Factors Signal Transduction Stem cells System Testing Tumor Suppressor Proteins Up-Regulation Viral hepatitis Virus Inactivation base cancer cell cancer initiation cancer stem cell cell type effective therapy functional mimics gain of function hepatocellular carcinoma cell line in vivo inhibitor/antagonist liver cell proliferation loss of function member mouse model mutant notch protein novel oncoprotein p21 outcome forecast prevent progenitor research study response self-renewal tool tumor tumor progression tumor specificity tumorigenesis

项目摘要

DESCRIPTION (provided by applicant): More than 600,000 people die from Hepatocellular carcinoma (HCC) worldwide annually. The environmental factors that cause HCC are well known and include infection by hepatitis B and C viruses (HBV and HCV), exposure to Aflatoxin B1, and excessive alcohol intake. However, no effective treatments exist for HCC and the prognosis of HCC patients is usually poor, with an overall median survival of less than one year. The RB tumor suppressor and its family member's p107 and p130 are functionally inactivated in nearly all cases of human HCC. This inactivation is due to increased CDK4 kinase activity resulting from the silencing of the CDK4 inhibitor p16 or from increased expression of the CDK4 partner Cyclin D1. In addition, some proteins produced by HBV and HCV can inactivate RB family members, including by triggering their degradation. We generated a mouse model for human HCC by deleting RB family genes in the liver of adult mice to model this functional inactivation of RB family proteins. RB/p107/p130 triple knockout (TKO) mice develop liver tumors whose histology and gene expression profiles resemble human HCCs. The activity of E2F transcription factors, which are normally inhibited by the RB family, is high in TKO HCC cells. TKO HCCs initiate from progenitor cells and not hepatocytes, which do not divide due to unknown mechanisms that suppress their proliferation. The TKO HCC model provides a unique in vivo system to query the mechanisms of tumorigenesis in the liver and to specifically interrogate how RB/E2F transcriptional regulatory complexes control HCC development. Our general hypothesis is that inactivation of the RB pathway drives cancer initiation at least in part by deregulating E2F activity and compromising the balance between regulatory networks in acutely sensitive cell populations. Specifically, we propose that increased E2F activity engages pathways that promote the expansion of mutant cells, including liver progenitors, but also triggers negative feedback loops preventing cancer initiation from mature hepatocytes and limiting the growth of HCC cells. We will first test the specific hypothesis that activation of p21 by E2F in the TKO model blocks the proliferation of hepatocytes, thereby preventing HCC initiation from these mature cells. Next, we will test the idea that activation of Notch signaling y E2F limits the expansion of HCC cells during tumorigenesis. Finally, we will examine the possibility that activation of the EZH2 methyltransferase by E2F promotes the growth of both liver progenitors and HCC cells. To test these hypotheses, we will manipulate the activity of RB and E2F family members, p21 and CDK2, Notch pathway members, and EZH2 in adult liver progenitor cells, mature hepatocytes, and HCC cells in vivo. These experiments in mutant mice will be complemented by analyses of human liver cells ex vivo. Our studies will identify novel means to diagnose, detect, and treat HCC. In addition, because genetic, epigenetic, and/or viral inactivation of the RB pathway is a nearly universal event in human cancer cells, these studies are generally relevant to a broad cross-section of cancer patients.

描述（由申请人提供）：每年有60万人死于全球肝细胞癌（HCC）。引起HCC的环境因素是众所周知的，包括丙型肝炎和C病毒（HBV和HCV）感染，暴露于黄曲霉毒素B1和过多的酒精摄入量。但是，没有针对HCC的有效治疗方法，HCC患者的预后通常很差，总生存率不到一年。在几乎所有人类HCC病例中，RB肿瘤抑制剂及其家人的P107和P130在功能上均灭活。这种灭活是由于CDK4抑制剂p16沉默或CDK4伴侣Cyclin d1 D1导致的CDK4激酶活性增加所致。此外，HBV和HCV生产的一些蛋白质可能会使RB家族成员失活，包括触发其降解。我们通过删除成年小鼠肝脏中的RB家族基因来建模RB家族蛋白的功能失活，从而生成人类HCC的小鼠模型。 RB/P107/P130三敲除（TKO）小鼠会发展出肝肿瘤，其组织学和基因表达谱类似于人类HCC。在TKO HCC细胞中，E2F转录因子通常抑制的E2F转录因子的活性很高。 TKO HCC是从祖细胞而不是肝细胞启动的，由于未知机制抑制了它们的增殖，它们不会分裂。 TKO HCC模型提供了一个独特的体内系统，以查询肝脏中肿瘤发生的机制，并专门询问RB/E2F转录调节络合物如何控制HCC的发展。我们的一般假设是，RB途径的失活至少会驱动癌症的开始通过放大E2F活性并损害敏锐敏感细胞种群中调节网络之间的平衡。具体而言，我们建议增加E2F活性的途径，促进包括肝祖细胞在内的突变细胞扩张的途径，但也会触发负反馈回路，从而防止成熟的肝细胞癌症引发并限制HCC细胞的生长。我们将首先检验P21激活的特定假设 TKO模型中的E2F阻断了肝细胞的增殖，从而防止了这些成熟细胞的HCC启动。接下来，我们将测试以下想法：Notch信号Y E2F的激活限制了肿瘤发生过程中HCC细胞的膨胀。最后，我们将研究E2F通过E2F激活EZH2甲基转移酶的可能性，促进肝脏祖细胞和HCC细胞的生长。为了检验这些假设，我们将操纵RB和E2F家族成员，P21和CDK2，Notch Pathway成员和EZH2在成年肝脏祖细胞，成熟的肝细胞和体内HCC细胞中的活性。这些在突变小鼠中的实验将通过体内的人肝细胞的分析来补充。我们的研究将确定诊断，检测和治疗HCC的新颖手段。此外，由于RB途径的遗传，表观遗传和/或病毒灭活是人类癌细胞中几乎普遍的事件，因此这些研究通常与癌症患者的广泛横截面有关。