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，并且在人类淋巴瘤中经常被激活。 v-akt 是逆转录病毒携带的癌基因，可诱导小鼠胸腺 T 细胞淋巴瘤，而在未成熟 T 细胞中表达组成型活性 Akt (Myr-Akt) 的转基因小鼠会发生胸腺淋巴瘤。 Myr-Akt2 小鼠模型的多发性胸腺淋巴瘤被发现存在 6 号染色体的新型倒位，即 inv(6)，在 T 细胞受体 β 链基因座 (Tcrb) 和 Dss1 基因中存在断点。没有检测到融合蛋白，但重排使 Tcrb 增强子靠近几个持续上调的基因和非编码 RNA。最近报道了几种常见人类癌症中编码转录因子 Dlx5 的候选基因之一的上调，表明该同源盒基因在异常表达时可能具有致癌性。该项目的广泛、长期目标是提高我们对 Akt2 在淋巴瘤发生中的作用的理解，并阐明 Dlx5 上调与 Akt2 信号传导共同促进肿瘤形成的机制。具体目标是： 1) 评估上调的 Dlx5 与淋巴瘤形成的相关性。我们将确定具有 inv(6) 的胸腺淋巴瘤细胞的细胞增殖和/或活力是否受到 Dlx5 敲低的抑制。此外，还将进行骨髓嵌合体实验，以确定敲除来自具有高inv(6)阳性淋巴瘤发生率的创始系的非恶性骨髓细胞中的Dlx5是否会抑制受体野生型同窝小鼠的肿瘤形成。我们还将检查转基因小鼠在胸腺中过度表达 Dlx5 是否会发展为自发性 T 细胞淋巴瘤。 2) 使用直接遗传学方法，测试Dlx5是否与Akt2在胸腺肿瘤发展中协同作用。 Myr-Akt2 小鼠将与 Dlx5 转基因小鼠或条件性 Dlx5 敲除小鼠杂交，以确定肿瘤发展是否分别被加速或抑制。我们还将通过评估单独表达 Dlx5 或 Myr-Akt2 与组合表达 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 在肿瘤发生中合作的机制。 3) 确定淋巴瘤的发展和已形成肿瘤的维持是否需要 Akt2 信号传导的过度激活。将采用荧光原位杂交、PCR 和磁共振显微成像分析来确定 inv(6) 在肿瘤发展过程中何时出现；然后将采用早期干预策略来确定 Akt2 信号传导的抑制是否可以预防或延缓淋巴瘤的发展。此外，还将开发诱导型 Myr-Akt2 模型，以确定已确定的胸腺淋巴瘤中 Akt2 失活是否会导致肿瘤消退。该项目将增强我们对 Akt2 介导的淋巴瘤发生以及 Akt2 与新型假定癌基因 Dlx5 之间合作的理解，Dlx5 的激活也可能有助于各种人类癌症的发病机制。公共卫生相关性：细胞酶 AKT2 在大多数人类癌症中高度活跃，可促进肿瘤细胞存活和对化疗的抵抗力。我们在小鼠模型中的研究发现了一种新基因 (Dlx5)，当表达异常时，该基因与激活的 Akt2 一起作用，诱导胸腺侵袭性淋巴瘤。最近发现，人类 DLX5 在一些淋巴瘤以及肺癌等更常见的肿瘤中表达水平升高，这表明 DLX5 可能作为人类 AKT2 相关恶性肿瘤的新治疗靶点。