MOUSE MAMMARY TUMOR VIRUS AND DETERMINANTS OF LEUKEMOGENICITY

小鼠乳腺肿瘤病毒和致白血病的决定因素

• 批准号: 6580352
• 负责人: Jaquelin Page Dudley
• 金额: $ 10.37万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-03-01 至 2003-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6580352
• 关键词: B lymphocyte; genetic regulatory element; genetically modified animals; laboratory mouse; molecular cloning; mouse leukemia; mouse mammary tumor virus; murine leukemia virus; nucleic acid repetitive sequence; open reading frames; protooncogene; provirus; recombinant virus; superantigens; transcription factor; viral carcinogenesis; virus infection mechanism; virus integration; virus related neoplasm /cancer

The mouse mammary tumor virus (MMTV) induces primarily breast cancers in mice. However, some highly related MMTV strains (e.g., TBLV) induce T-cell tumors, but not mammary carcinomas. The major differences between (LTRs) at the ends of pro-viral DNA. These differences include (i) loss of negative regulatory elements (NREs) that suppress MMTV transcription in lymphoid tissues, including thymus, (ii) loss of the C-terminal one-third of the superantigen gene that is involved in MMTV transmission from lymphoid to mammary cells, and (iii) triplication of 62 bp flanking the LTR deletion. In this grant application, regions of the TBLV genome that are responsible for thymotropism will be assessed. First, the specific cell types infected by TBLV will be analyzed, and optimal routes of infection will be determined. Second, specific mutations in known NREs, the triplicated region of the sag open reading frame will be introduced into a mammotropic MMTV and tested for their ability to infect specific cell types and to cause leukemias. Third, the triplicated region shown to enhance MMTV transcription in T-cells will be analyzed for the binding of cellular transcription factors, and these factors will be identified. Fourth, if the LTR is not sufficient to reproduce the cell-type tropism and leukemogenicity of TBLV, we will construct chimeras between mammotropic and thymotropic strains of MMTV and test these chimeras for their ability to infect different cell types and induce disease. In the second specific aim, we will continue our studies to assess the role of specific TBLV integration sites in virally-induced leukemias. Previously identified TBLV integrations will be analyzed by PCR and by pulsed field gel electrophoresis. Integrations in the c-myc locus also will be assessed in leukemias induced by MMTV pro-viruses that have a truncated sag gene and lack the NREs, but also lack the specific triplicated region found in TBLV. These experiments and studies of transgenic mice that have a mutant MMTV or TBLV LTR upstream of c-myc should provide information about whether LTR changes affect integration site choice or the ability to stimulate c-myc expression. These results should elucidate the factors conducive for the development of human leukemia and permit the development of novel strategies for their treatment.

小鼠乳腺肿瘤病毒（MMTV）主要诱发小鼠乳腺癌。然而，一些高度相关的 MMTV 毒株（例如 TBLV）会诱发 T 细胞肿瘤，但不会诱发乳腺癌。前病毒 DNA 末端 (LTR) 之间的主要差异。这些差异包括 (i) 抑制淋巴组织（包括胸腺）中 MMTV 转录的负调控元件 (NRE) 的丢失，(ii) 参与 MMTV 从淋巴向乳腺细胞传播的超抗原基因 C 端三分之一的丢失，以及 (iii) LTR 缺失侧翼 62 bp 的三倍体。在本次拨款申请中，将评估 TBLV 基因组中负责促胸腺功能的区域。首先，将分析TBLV感染的具体细胞类型，并确定最佳感染途径。其次，已知 NRE 中的特定突变，下垂开放阅读框的三重区域将被引入促乳腺 MMTV 中，并测试其感染特定细胞类型和引起白血病的能力。第三，将分析显示增强 T 细胞中 MMTV 转录的三重区域的细胞转录因子的结合，并鉴定这些因子。第四，如果LTR不足以重现TBLV的细胞类型趋向性和致白血病性，我们将构建MMTV的亲乳腺株和亲胸腺株之间的嵌合体，并测试这些嵌合体感染不同细胞类型和诱导疾病的能力。在第二个具体目标中，我们将继续研究评估特定 TBLV 整合位点在病毒诱导的白血病中的作用。先前鉴定的 TBLV 整合将通过 PCR 和脉冲场凝胶电泳进行分析。 c-myc 位点的整合也将在由 MMTV 前病毒诱导的白血病中进行评估，MMTV 前病毒具有截短的 sag 基因并缺乏 NRE，但也缺乏 TBLV 中发现的特定三重区域。这些对 c-myc 上游具有突变 MMTV 或 TBLV LTR 的转基因小鼠进行的实验和研究应提供有关 LTR 变化是否影响整合位点选择或刺激 c-myc 表达的能力的信息。这些结果应阐明有利于人类白血病发展的因素，并允许开发新的治疗策略。