DNMT3A-BCL11A-FLT3基因间的调控关系及其对白血病形成的影响

Leukemia is a severe form of hematologic malignancy with generally poor prognosis. Current genomic researches have increasingly revealed remarkable molecular alterations of this disease. However, whether and how these changes affect the development of leukemia, and especially, whether and how they interact with each other towards leukemogenesis, remain largely enigmatic. It is known that DNMT3A, BCL11A and FLT3 are important genes whose abnormalities contribute to the development of various subtypes of leukemia. Our preliminary study has found that, in blast cells obtained from patients with leukemia, high expression levels of BCL11A are significantly correlated with DNMT3A and FLT3 mutations. Together with other supportive evidence, we hereby hypothesize that a regulatory axis among DNMT3A, BCL11A and FLT3 may exist, and alterations of this axis can affect malignant transformation. Specifically, we will investigate (1) whether DNMT3A regulates BCL11A and how this regulation affects the formation of leukemia, (2) whether BCL11A regulates FLT3 and affects leukemia, and (3) whether DNMT3A also regulates FLT3. It is our expectation that outcomes of this project will aid our understanding of leukemia with aberrant DNMT3A, BCL11A and FLT3, and possibly, improve clinical diagnosis and treatment of leukemia.

白血病是我国重点防治的恶性肿瘤之一，病因尚未完全清楚，治愈率低下，需进一步弄清其发病机制。现代白血病遗传学研究揭示了越来越多的分子遗传学异常，但对其致病机理、尤其是它们之间的相互作用关系所知不多。已知DNMT3A、BCL11A和FLT3是参与白血病发生的重要分子。我们前期研究发现，白血病人标本中BCL11A的高表达水平与FLT3-ITD突变和DNMT3A-R882突变具有显著的相关性。结合其它研究结果，我们认为：在白血病细胞中，可能存在DNMT3A-BCL11A-FLT3分子调控轴，其异常改变可能导致白血病的发生和发展。本申请项目拟通过分子生物学、细胞生物学、小鼠模型和临床标本的研究，探讨这三个基因间的调控关系，以及DNMT3A-BCL11A-FLT3分子调控轴对白血病发生发展的影响。本项目的实施，将有助于加深我们对这些基因异常导致白血病的机制性的认识，可能改善白血病的临床诊断和治疗。

根据设计书的计划要点，我们的研究内容按照计划逐步实施，但对研究重点方面有所侧重。我们扩大收集了临床白血病病人骨髓和外周血标本，进行实验系统的建立、测试、控制和完善，并获取部分的基础数据。同时构建各种逆转录基因表达载体以及逆转录病毒，然后对各稳转细胞进行基因表达水平检测和相关的分子生物学检测，重点选取了HL-60细胞株进行了如细胞增殖、分化检测，甲基化水平检测等。Dual-Luciferase Reporter Assay System分析DNMT3A-BCL11A-FLT3之间的调控关系。同时建立白血病小鼠模型以及体内相关的分子生物学检测，如细胞增殖、分化，基因表达水平改变等。