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在肿瘤发生中起着核心作用，并且在人淋巴瘤中经常被激活。 V-AKT是一种由逆转录病毒所包含的致癌基因，该逆转录病毒在小鼠中诱导胸腺T细胞淋巴瘤，并且在未成熟的T细胞中特异性地表达Akt（MyR-Akt）的组成型活性形式的转基因小鼠在未成熟的T细胞中会发展出胸腺淋巴瘤。发现来自MYR-AKT2小鼠模型的多个胸腺淋巴瘤具有6种新型染色体，INV（6）的新反转，在T细胞受体β链基因座（TCRB）和DSS1基因中具有断点。未检测到融合蛋白，但是重排将TCRB增强子放置在几个基因和非编码RNA附近，这些RNA始终受到调节。最近在几种常见的人类癌症中报道了这些候选基因之一，编码转录因子DLX5，这表明该同源基因在异常表达时可能会致癌。该项目的广泛长期目标是提高我们对AKT2在淋巴作用和阐明机制中的作用的理解，通过这些机制，通过这些机制，DLX5通过AKT2信号的调节以促进肿瘤形成。具体目的是：1）评估上调DLX5与淋巴瘤形成的相关性。我们将通过击倒DLX5来抑制胸腺淋巴瘤细胞的细胞增殖和/或活力。此外，将进行骨髓嵌合体实验，以确定来自INV高发病率（6）阳性淋巴瘤的创始人线中的非理性骨髓细胞中DLX5是否抑制受体野生型同eltmates中的肿瘤形成。我们还将检查转基因小鼠是否在胸腺中过表达DLX5是否发展为自发的T细胞淋巴瘤。 2）使用直接的遗传方法，测试DLX5是否在胸腺肿瘤发育中与Akt2合作。 MYR-AKT2小鼠将与DLX5转基因小鼠或条件DLX5敲除小鼠交叉，以确定肿瘤发育是否加速或抑制。我们还将通过评估单独表达DLX5或MYR-AKT2的细胞生长，增殖和生存率来确定AKT2与肿瘤发生中DLX5合作的机制。 3）确定淋巴瘤发育和既定肿瘤的维持是否需要AKT2信号的过度激活。将采用荧光原位杂交，PCR和磁共振微成像分析来确定何时在肿瘤发育期间出现INV（6）；然后，将使用早期干预策略来确定抑制AKT2信号传导是否阻止或延迟淋巴瘤的发展。此外，将开发可诱导的MYR-AKT2模型，以确定在已建立的胸腺淋巴瘤中Akt2失活是否会导致肿瘤退化。该项目将增强我们对Akt2介导的淋巴作用和AKT2与新型推定的致癌基因DLX5之间的合作的理解，其激活也可能有助于各种人类癌的发病机理。公共卫生相关性：细胞酶AKT2在大多数人类癌症中都是多动的，可促进肿瘤细胞的存活和对化学疗法的抗性。我们在小鼠模型中的研究发现了一种新型基因（DLX5），该基因异常表达，与活化的Akt2一起工作以诱导胸腺的侵袭性淋巴瘤。最近已显示人类DLX5在某些淋巴瘤以及更常见的肿瘤（如肺癌）中以较高的水平表达，这表明DLX5可以作为与人AKT2相关的恶性肿瘤中的新治疗靶标。