Murine models of activated FLT3 receptor tyrosine kinase

激活FLT3受体酪氨酸激酶的小鼠模型

• 批准号: 7227183
• 负责人: BENJAMIN H LEE
• 金额: $ 14.01万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-05-01 至 2008-04-05
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7227183
• 关键词: Murine; models; activated; FLT3; receptor

DESCRIPTION (provided by applicant): FLT3 is the most frequently mutated gene in cases of acute myelogenous leukemia (AML). About 30-35% of patients have either internal tandem duplications (FLT3-ITD) in the juxtamembrane (JM) domain or mutations in the activating loop of FLT3, the consequences of which are constitutive activation of the tyrosine kinase. FLT3 activating mutations have also been described in acute lymphoblastic leukemias including subsets harboring 11q23 rearrangements implicating it in the pathogenesis of a broader spectrum of hematopoietic neoplasms. Significantly these mutations confer a poor clinical prognosis to patients in most retrospective studies providing a compelling basis for understanding the pathogenesis of FLT3-ITD mediated disease and developing and testing new therapies that can specifically target the FLT3 molecule. The research described in this 5-year proposal outlines specific aims designed to investigate the in vivo effects of an activating FLT3-ITD mutation in a whole animal system through the characterization of a novel FLT3-ITD knock-in mutant mouse model which we have generated using a combination of standard transgenic and embryonic (ES) cell gene-targeting techniques. Expression of activated FLT3 from the endogenous murine FLT3 promoter in these animals provides distinct advantages over retroviral transduction models where differences in expression levels of activated FLT3 may affect disease phenotype and avoids potential mutations introduced by retroviral integration. These animal models should provide insights not only into how activated FLT3 contributes to the pathogenesis of leukemia, but also into the biological role of this gene in normal hematopoiesis. Moreover, these mice should provide powerful reagents that can be used to assess the efficacy of targeted drug therapy against FLT3-induced leukemias including the use of both currently established FLT3 inhibitors and new generation high affinity FLT3 inhibitors. Finally, these mice can be employed with other established mouse model systems to further our understanding of how different classes of mutations can cooperate with one another in the development of acute leukemia. Specific aims include: (1) To characterize a FLT3-ITD knock-in mouse model including (a) assessing effects of FLT3-ITD expression from the endogenous FLT3 promoter on hematopoietic progenitor development and (b) detailed characterization of mono-allelic and bi-allelic FLT3-ITD knock-in phenotypes; (2) To assess the therapeutic efficacy of small molecule FLT3 tyrosine kinase inhibitors in animal drug trials with FLT3-ITD mouse lines; and (3) To investigate a cooperative model of acute leukemia by crossing FLT3-ITD mice with other leukemogenic mouse models including PML/RARalpha, AML1/ETO, and C/EBPalpha p30 transgenic mouse lines and assessing for therapeutic efficacy with novel small molecule inhibitors.

描述（由申请人提供）：FLT3 是急性髓性白血病 (AML) 病例中最常见的突变基因。大约 30-35% 的患者在近膜 (JM) 结构域中存在内部串联重复 (FLT3-ITD)，或者在 FLT3 激活环中存在突变，其后果是酪氨酸激酶的组成型激活。 FLT3 激活突变也在急性淋巴细胞白血病中得到描述，包括含有 11q23 重排的亚型，表明它与更广泛的造血系统肿瘤的发病机制有关。值得注意的是，在大多数回顾性研究中，这些突变给患者带来了不良的临床预后，为了解 FLT3-ITD 介导的疾病的发病机制以及开发和测试专门针对 FLT3 分子的新疗法提供了令人信服的基础。 这项为期 5 年的提案中描述的研究概述了具体目标，旨在通过我们使用标准转基因和胚胎 (ES) 细胞基因靶向技术相结合生成的新型 FLT3-ITD 敲入突变小鼠模型的表征来研究激活 FLT3-ITD 突变在整个动物系统中的体内影响。在这些动物中，从内源性鼠FLT3启动子表达活化的FLT3比逆转录病毒转导模型具有明显的优势，在逆转录病毒转导模型中，活化的FLT3表达水平的差异可能影响疾病表型并避免逆转录病毒整合引入的潜在突变。这些动物模型不仅应该提供关于激活的FLT3如何促进白血病发病机制的见解，还应该提供该基因在正常造血中的生物学作用的见解。此外，这些小鼠应该提供强大的试剂，可用于评估针对FLT3诱导的白血病的靶向药物治疗的功效，包括使用目前建立的FLT3抑制剂和新一代高亲和力FLT3抑制剂。最后，这些小鼠可以与其他已建立的小鼠模型系统一起使用，以进一步了解不同类别的突变如何在急性白血病的发展中相互配合。具体目标包括：（1）表征FLT3-ITD敲入小鼠模型，包括（a）评估内源FLT3启动子的FLT3-ITD表达对造血祖细胞发育的影响，以及（b）单等位基因和双等位基因FLT3-ITD敲入表型的详细表征； (2) 在FLT3-ITD小鼠系动物药物试验中评估小分子FLT3酪氨酸激酶抑制剂的治疗效果； (3) 通过将 FLT3-ITD 小鼠与其他白血病小鼠模型（包括 PML/RARα、AML1/ETO 和 C/EBPα p30 转基因小鼠系）杂交，研究急性白血病的合作模型，并评估新型小分子抑制剂的治疗效果。