Basis for Lymphomagenesis in Akt2 Transgenic Mice

Akt2 转基因小鼠淋巴瘤发生的基础

• 批准号: 7743099
• 负责人: Joseph R. Testa
• 金额: $ 45.21万
• 依托单位: FOX CHASE CANCER CENTER
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-05-01 至 2013-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7743099
• 关键词: AKT1 gene; AKT2 gene; AKT3 gene; Binding; Bone Marrow; Candidate Disease Gene; Cell Proliferation; Cell Survival; Cells; Chimera organism; Chimeric Proteins; Chromosomes, Human, Pair 6; Common Neoplasm; Cytogenetic Analysis; DNA Sequence Rearrangement; Development; Early treatment; Endometrial Carcinoma; Engineering; Enhancers; Enzymes; Fluorescent in Situ Hybridization; Genes; Genetic; Homeobox Genes; Human; Incidence; Intervention; Investigation; Knockout Mice; Link; Lung; Lymphoma; Lymphomagenesis; Magnetic Resonance; Maintenance; Malignant Neoplasms; Malignant neoplasm of lung; Malignant neoplasm of ovary; Marrow; Mediating; Membrane; Modeling; Mus; Non-Malignant; Oncogenes; Oncogenic; Ovarian; Pancreatic carcinoma; Pathogenesis; Phosphotransferases; Play; Primary Neoplasm; Protein Binding; Proto-Oncogene Proteins c-akt; Public Health; Reporting; Resistance; Retroviridae; Role; Signal Transduction; Signal Transduction Pathway; Small Interfering RNA; T-Cell Lymphoma; T-Lymphocyte; Testing; Thymic Lymphoma; Thymus Gland; Thymus Neoplasms; Transcript; Transcription factor genes; Transgenic Mice; Transgenic Organisms; Tumor Suppressor Proteins; Untranslated RNA; Up-Regulation; Work; base; beta Chain Antigen T Cell Receptor; cancer cell; cancer type; cell growth; chemotherapy; design; improved; in vivo; knock-down; mouse model; neoplastic cell; new therapeutic target; novel; overexpression; prevent; public health relevance; research study; thymocyte; transcription factor; tumor; tumor growth; tumorigenesis

DESCRIPTION (provided by applicant): AKT plays a central role in tumorigenesis and is frequently activated in human lymphoma. v-akt is an oncogene harbored by a retrovirus that induced thymic T-cell lymphomas in mice, and transgenic mice expressing constitutively active forms of Akt (Myr-Akt) specifically in immature T cells develop thymic lymphomas. Multiple thymic lymphomas from a Myr-Akt2 mouse model were found to harbor a novel inversion of chromosome 6, inv(6), with breakpoints in the T-cell receptor beta chain locus (Tcrb) and Dss1 gene. A fusion protein was not detected, but the rearrangement places the Tcrb enhancer near several genes and noncoding RNAs that are consistently up regulated. Up regulation of one of these candidate genes, encoding the transcription factor Dlx5, has recently been reported in several common human cancers, suggesting that this homeobox gene may be oncogenic when expressed aberrantly. The broad, long-term objective of this project is to improve our understanding of the role of Akt2 in lymphomagenesis and elucidate mechanisms by which up regulation of Dlx5 converges with Akt2 signaling to promote tumor formation. The specific aims are: 1) Assess the relevance of up-regulated Dlx5 to lymphoma formation. We will determine if cell proliferation and/or viability of thymic lymphoma cells with the inv(6) are inhibited by knock down of Dlx5. In addition, bone marrow chimera experiments will be carried out to determine if knock down of Dlx5 in non-malignant marrow cells from a founder line with high incidence of inv(6)-positive lymphomas inhibits tumor formation in recipient wild-type littermates. We will also examine if transgenic mice engineered to overexpress Dlx5 in the thymus develop spontaneous T-cell lymphomas. 2) Using a direct genetic approach, test whether Dlx5 cooperates with Akt2 in thymic tumor development. Myr-Akt2 mice will be crossed with Dlx5 transgenic mice or conditional Dlx5 knockout mice to determine if tumor development is accelerated or inhibited, respectively. We will also identify mechanisms by which Akt2 cooperates with Dlx5 in tumorigenesis by assessing cell growth, proliferation and survival in primary thymocytes from transgenic mice expressing Dlx5 or Myr-Akt2 alone versus in combination. 3) Determine if hyperactivation of Akt2 signaling is required for both lymphoma development and maintenance of established tumors. Fluorescence in situ hybridization, PCR, and magnetic resonance microimaging analyses will be employed to establish when the inv(6) arises during tumor development; then an early intervention strategy will be used to determine if inhibition of Akt2 signaling prevents or delays the development of lymphoma. In addition, an inducible Myr-Akt2 model will be developed to ascertain if inactivation of Akt2 in established thymic lymphomas results in tumor regression. This project will enhance our understanding of Akt2-mediated lymphomagenesis and cooperation between Akt2 and a novel putative oncogene, Dlx5, whose activation may also contribute to the pathogenesis of various human cancers. PUBLIC HEALTH RELEVANCE: The cellular enzyme AKT2 is hyperactive in most human cancers and promotes tumor cell survival and resistance to chemotherapy. Our studies in a mouse model have uncovered a novel gene (Dlx5) that, when expressed abnormally, works together with activated Akt2 to induce aggressive lymphomas of the thymus. Human DLX5 has recently been shown to be expressed at elevated levels in some lymphomas as well as more common tumors such as lung cancers, suggesting that DLX5 may serve as a new therapeutic target in human AKT2-related malignancies.

描述(由申请人提供)：AKT在肿瘤发生中发挥核心作用，在人类淋巴瘤中经常被激活。V-AKT是逆转录病毒携带的一种癌基因，可诱导小鼠胸腺T细胞淋巴瘤，而在未成熟T细胞中特异表达活性形式Akt(Myr-Akt)的转基因小鼠会发生胸腺淋巴瘤。来自Myr-Akt2小鼠模型的多发性胸腺淋巴瘤被发现含有一种新的6号染色体倒位，inv(6)，带有T细胞受体β链基因(Tcrb)和Dss1基因的断裂点。没有检测到融合蛋白，但重排将Tcrb增强子放置在几个持续上调的基因和非编码RNA附近。这些候选基因之一，编码转录因子Dlx5，最近在几种常见的人类癌症中被报道上调，这表明当异常表达时，这种同源框基因可能是致癌的。这个项目的广泛和长期目标是提高我们对Akt2在淋巴肿瘤发生中的作用的理解，并阐明Dlx5上调与Akt2信号融合促进肿瘤形成的机制。其具体目的是：1)评估上调的Dlx5与淋巴瘤形成的相关性。我们将确定带有inv(6)的胸腺淋巴瘤细胞的细胞增殖和/或活性是否受到Dlx5基因敲除的抑制。此外，还将进行骨髓嵌合体实验，以确定从inv(6)阳性淋巴瘤高发的创建者系的非恶性骨髓细胞中敲除Dlx5是否能抑制受体野生型小鼠的肿瘤形成。我们还将检查在胸腺中过表达Dlx5的转基因小鼠是否会患上自发性T细胞淋巴瘤。2)采用直接遗传学方法，检验Dlx5与Akt2在胸腺肿瘤发生中是否存在协同作用。MYR-Akt2小鼠将分别与Dlx5转基因小鼠或条件性Dlx5基因敲除小鼠杂交，以确定肿瘤的发展是加速还是抑制。我们还将通过评估单独或联合表达Dlx5或Myr-Akt2的转基因小鼠的原代胸腺细胞的细胞生长、增殖和存活来确定Akt2与Dlx5在肿瘤发生中的合作机制。3)确定Akt2信号的过度激活是否对淋巴瘤的发生和已建立的肿瘤的维持都是必需的。荧光原位杂交、聚合酶链式反应和磁共振显微成像分析将被用来确定在肿瘤发展过程中何时出现inv(6)；然后将使用早期干预策略来确定抑制Akt2信号是预防还是延迟淋巴瘤的发展。此外，还将开发一个可诱导的Myr-Akt2模型，以确定在已建立的胸腺淋巴瘤中Akt2的失活是否会导致肿瘤消退。这个项目将加深我们对Akt2介导的淋巴肿瘤发生的理解，以及Akt2和一个新的假定癌基因Dlx5之间的合作，Dlx5基因的激活可能也有助于各种人类癌症的发生。公共卫生相关性：细胞酶AKT2在大多数人类癌症中高度活跃，并促进肿瘤细胞存活和对化疗的耐药性。我们在小鼠模型中的研究发现了一种新的基因(Dlx5)，当异常表达时，它与激活的Akt2一起工作，诱导胸腺侵袭性淋巴瘤。最近的研究表明，人类DLX5在一些淋巴瘤以及肺癌等常见肿瘤中的表达水平升高，这表明DLX5可能成为人类AKT2相关恶性肿瘤的新的治疗靶点。