环形RNA在急性早幼粒细胞白血病发病及治疗中的功能和机制研究

Circular RNAs (circRNAs) are a novel class of powerful regulators during gene regulation, due to their abundant expression, stable structures, high conservation and tissue-specific expression properties. CircRNAs have been recently found to be involved in the development of several diseases, including cancer. However, their roles in the development and treatment of leukemia remain unclear. Acute promyelocytic leukemia (APL) is a disease with aberrant transcriptional regulation due to the fusion between the promyelocytic leukemia gene and the retinoic acid receptor α gene, which generates the PML/RARα fusion gene. All-trans retinoic acid (ATRA) is able to convert the oncogenic transcriptional programs initiated by PML/RARα, thereby resulting in complete remission in 90% of APL patients. Comprehensive mechanism studies are continuing to expand our understanding to the complexity of the APL development and its effective treatment. Our pilot study identified a series of circRNAs, which were exclusively expressed in APL or significantly regulated during ATRA-induced differentiation of APL cells. The detailed functional study on circ-RELL1, one of the APL-related circRNAs, found that circ-RELL1 was indispensable for ATRA-induced differentiation of APL cells. These preliminary data suggested that circRNAs were actively engaged in the development and treatment processes of APL. In this study, we will investigate the whole transcriptome profiling of circRNAs in APL using ribo-minus RNA-seq sequencing. First, we will identify APL-specific circRNAs using the circRNA profiling of APL cells, including primary samples and cell lines, as compared to that of non-APL samples or other types of normal leukocytes. Second, we will obtain the differentially regulated circRNAs using the time-series circRNA profiling during ATRA treatment. Third, based on circRNA profiling, we will analyze their genome-wide characteristics, including the genomic distribution, regulatory pattern, biogenesis, composition and so on. According to these features, we will identify the potential key circRNAs in APL. Fourth, using molecular biology, cellular biology and animal experiments, we will investigate the functional roles of these circRNAs in the pathogenesis and treatment of APL in vivo and in vitro. Finally, we will explore the underlying regulatory mechanisms of these key circRNAs. This study will deepen our understanding of the pathogenesis and effective treatments of APL at the layer of circRNA regulation, thus providing a comprehensive picture of transcriptional deregulation in APL and new ideas for the investigation of other leukemia types.

环形RNA是一类新发现的在基因调控中发挥重要作用的调控分子。由于其数量众多、保守性高、不易降解、组织特异性强等特征，使其具有有别于其他调控分子的作用。急性早幼粒细胞白血病（APL）是一类由于融合转录因子引起基因调控异常的疾病，深入的研究不断揭示新的机制参与其发生。我们前期研究识别了APL特异的及在维甲酸诱导分化中差异表达的环形RNA谱，并发现了新鉴定的环形RNA的功能，提示环形RNA活跃地参与了APL的发生和治疗。本项目拟通过全转录组测序识别与APL发病及治疗相关的环形RNA表达谱，解析其全基因组的分布特征及调控模式，并筛选与APL密切相关的关键环形RNA。通过分子、细胞生物学和动物实验，在体内和体外研究环形RNA在APL发病及治疗中的功能和作用机制。这一研究将拓展我们对于APL在环形RNA调控层面的认知，为系统诠释APL的异常调控及有效治疗机制提供依据，并为其他白血病的研究提供思路。

急性髓细胞白血病（AML）发生的异常转录调控是白血病发生发展和治疗研究的核心。本项目首先从全基因组和全转录组水平绘制了APL关键致病融合蛋白PML/RARα的DNA结合全图谱，以及APL特征性非编码RNA（circRNA和lncRNA）的调控谱。在高通量研究的基础上从单基因水平揭示多组学研究鉴定获得的关键circRNAs（如circSPI1、circ-HIPK2等）、lncRNA CRNDE和基因（如LMO2、GFI1、RUNX1等）在白血病发生中的功能及机制。发现关键circRNA circSPI1通过拮抗关键造血转录因子SPI1功能参与白血病发生；揭示ATRA作用中circ-HIPK2可以发挥海绵作用通过靶向miR-124-3p参与分化调节；解析了lncRNA CRNDE在多种实体肿瘤和血液肿瘤中的表达模式；深入研究揭示lncRNA CRNDE能协同PML/RARα促进APL发生，并且参与NPM1突变AML的发生；揭示PML/RARα抑制LMO2的表达干扰红系分化的进程，通过染色质构象激活GFI1的表达。最后，我们从转化和应用的角度，解析了针对AML预后不良相关的危险因素，例如可变剪接事件、白血病细胞克隆演化、IL8/TNFα等在AML预后中的意义，并开发了两项基于人工智能的基因调控大数据的分析和展示方法。本研究对揭示白血病发生发展的分子机制及设计个体化治疗方案具有积极的理论价值。在本项目的资助下，发表包括Blood（1篇）、Cell Death Dis.（2篇）、Br J Haematol等SCI论文12篇。