The role of PTEN and AKT2 in the malignant transformation of liver progenitor cel

PTEN和AKT2在肝祖细胞恶性转化中的作用

• 批准号: 8826050
• 负责人: Bangyan Stiles
• 金额: $ 34.21万
• 依托单位: UNIVERSITY OF SOUTHERN CALIFORNIA
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2016-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8826050
• 关键词: AKT1 gene; AKT2 gene; Address; Animal Model; Attenuated; Cell Culture Techniques; Cell Line; Cells; Chromosomes, Human, Pair 10; Clinical; Clinical Trials; Data; Development; Diet; Early Diagnosis; Event; Exhibits; Fatty Liver; Fatty-acid synthase; Fibrosis; Foundations; Future; Genetic; Goals; Growth; Health; Hepatocarcinogenesis; Hexokinase 2; Homologous Gene; Human; In Vitro; Injury; Knockout Mice; Lead; Lipids; Liver; Liver diseases; Liver neoplasms; Lung; Malignant - descriptor; Malignant neoplasm of liver; Mediating; Metabolic; Modeling; Molecular; Morphology; Mus; Mutant Strains Mice; Mutate; Mutation; Neoplasm Metastasis; PI3K/AKT; PTEN gene; Pathway interactions; Patients; Phenotype; Phosphoric Monoester Hydrolases; Premalignant; Process; Proliferating; Property; Protein-Serine-Threonine Kinases; Proto-Oncogene Proteins c-akt; Pyruvate Kinase; Regulation; Role; Signal Transduction; Specimen; Staging; Stem cells; Testing; Tumor Burden; Tumor Expansion; Tumor Suppressor Proteins; Up-Regulation; Xenograft Model; cancer therapy; carcinogenesis; cell growth; cell transformation; genetic association; human FRAP1 protein; in vivo; lipid biosynthesis; liver cancer prevention; liver injury; mouse model; neoplastic cell; overexpression; pre-clinical; progenitor; tensin; tool; treatment strategy; tumor; tumorigenesis

DESCRIPTION (provided by applicant): The long term goal of this project is to elucidate the molecular mechanism for liver cancer development. Toward this end, we developed and characterized a mouse model that carries deletion of a tumor suppressor that is often mutated (up to 44%) in human liver cancer. These mice, lacking the tumor suppressor PTEN (phosphatase and tensin homologue deleted on chromosome 10), displayed the progression from fatty liver disease to fibrosis to liver cancer and lung metastasis that has been observed in most human patients. Our preliminary data showed that a massive expansion of cells with progenitor cell properties occurs prior to tumor development in the Pten null model. We isolated these progenitor cells at the pre-malignant stage and found that they are tumor initiating cells (TICs) using xenograft models. In addition to isolating these cells, we have also begun to investigate the mechanism that lead to their growth and transformation. AKT is the best characterized downstream effector molecule of PTEN signaling. We found unexpectedly that loss of AKT2, known for its role in metabolic regulation but not AKT1, known for its role in cell growth/survival inhibits the development of tumors in the Pten null mice. A dramatic reduction in the progenitor cell activation morphology accompanied a significant delay in liver cancer development when Akt2 is simultaneously deleted with Pten. Our analysis shows that injury occurring with fatty liver is necessary for tumor development in the Pten null mice, whereas AKT2 attenuates fatty liver and injury. In this proposal, we plan to investigate the molecular and cellular mechanisms underlying the PTEN loss/AKT2 activation induced tumorigenesis. In the first aim, we will analyze the role of the AKT2 regulated lipogenesis on tumorigenesis and TIC cell activation. We will use dietary means to manipulate liver steatosis development and address the role of lipogenesis in tumorigenesis when PTEN or PTEN/AKT2 is lost. In the second aim, we will determine the effects of AKT2 on the transformation of the progenitor cells. We will overexpress myr-AKT2 and knockdown AKT2 in the unique Pten null and Pten/Akt2 double null liver progenitor cell lines that we have established and determine the effects of these manipulations on the abilities of these cells to form colonies, graft tumors and proliferate. We will additionally determine the molecular mechanisms (both canonical PI3K/AKT signaling and the unique metabolic signaling regulated by AKT2) that may underlie such a phenotype. In the last aim, we will determine the role of AKT2 in the upregulation of Wnt/ß-catenin signaling observed with Pten deletion. We have found that Wnt/ß-catenin, a pathway known to regulate progenitor cell activity, is activated in the Pten null mice. We hypothesize that AKT2 may antagonize the effect of PTEN on progenitor cell activation by controlling Wnt signaling. This may occur either through establishing a fatty liver/injury niche to induce Wnt expression or through directly regulating b-catenin activity within TICs. We will use both in TIC culture and in vivo approaches to address this aim. Together, these three aims will establish the causal effect of AKT2 activation on liver carcinogenesis in vivo and in vitro and the underlying mechanisms for such effect.

描述（由申请人提供）：本项目的长期目标是阐明肝癌发展的分子机制。为此，我们开发并表征了一种小鼠模型，该模型携带在人类肝癌中经常突变（高达44%）的肿瘤抑制因子的缺失。这些小鼠缺乏肿瘤抑制因子PTEN（10号染色体上缺失的磷酸酶和张力蛋白同源物），表现出从脂肪肝疾病到纤维化再到肝癌和肺转移的进展，这在大多数人类患者中已经观察到。我们的初步数据显示，在Pten无效模型中，具有祖细胞特性的细胞的大量扩增发生在肿瘤发展之前。我们在癌前阶段分离这些祖细胞，并使用异种移植模型发现它们是肿瘤起始细胞（TIC）。除了分离这些细胞外，我们还开始研究导致它们生长和转化的机制。AKT是PTEN信号传导的最佳表征的下游效应分子。我们意外地发现，已知其在代谢调节中的作用而不是已知其在细胞生长/存活中的作用的AKT 1的损失抑制Pten缺失小鼠中肿瘤的发展。当Akt 2与Pten同时缺失时，祖细胞活化形态的急剧减少伴随着肝癌发展的显著延迟。我们的分析表明，脂肪肝发生的损伤是Pten敲除小鼠肿瘤发展所必需的，而AKT 2减弱脂肪肝和损伤。在这个提议中，我们计划调查的分子和细胞机制的PTEN丢失/AKT 2激活诱导的肿瘤发生。在第一个目标中，我们将分析AKT 2调节的脂肪生成在肿瘤发生和TIC细胞活化中的作用。我们将使用饮食手段来操纵肝脏脂肪变性的发展，并解决当PTEN或PTEN/AKT 2丢失时脂肪生成在肿瘤发生中的作用。在第二个目标中，我们将确定AKT 2对祖细胞转化的影响。我们将在我们已经建立的独特的Pten无效和Pten/Akt 2双无效肝祖细胞系中过表达myr-AKT 2并敲低AKT 2，并确定这些细胞系的作用。 操纵这些细胞形成集落、移植肿瘤和增殖的能力。我们还将确定可能构成这种表型的分子机制（经典的PI 3 K/AKT信号传导和AKT 2调节的独特代谢信号传导）。在最后一个目标中，我们将确定AKT 2在Pten缺失时观察到的Wnt/β-连环蛋白信号传导上调中的作用。我们已经发现，Wnt/β-连环蛋白，一种已知调节祖细胞活性的途径，在Pten缺失小鼠中被激活。我们推测AKT 2可能通过控制Wnt信号通路拮抗PTEN对祖细胞活化的作用。这可能通过建立脂肪肝/损伤小生境以诱导Wnt表达或通过直接调节TIC内的β-连环蛋白活性而发生。我们将使用TIC培养和体内方法来实现这一目标。总之，这三个目标将建立AKT 2激活对体内和体外肝癌发生的因果关系，以及这种作用的潜在机制。