RUNX1长链非编码RNA在急性髓系白血病中的作用及机制研究

Acute myelogenous leukemia (AML) is the most common hematopoietic malignancy that primarily affects adults. The RUNX1 gene, also known as AML1, is a Runt-related transcription factor that regulates critical processes in hematopoiesis and defines the definitive hematopoietic stem cells. Located on chromosomal 21, the RUNX1 gene is involved in many forms of chromosomal translocations in leukemia. For example, t(8,21) is one of the most common chromosomal translocations found in acute myeloid leukemia (AML), where it results in a fusion protein between RUNX1 and ETO. However, the specific molecular mechanism underlying the chromosomal translocation and mutation in AML is poorly defined...Using a R3C (RNA-guided Chromatin Conformation Capture) method recently developed in our lab, we have demonstrated the presence of a novel long non-coding RNA (lncRNA) in the intron of RUNX1. Most interestingly, our preliminary data show that this lncRNA is a nuclear RNA and binds to regulatory elements of RUNX1, like promoter, as well as the DNA sequence in chromosome 8, to which the RUNX1 gene is fused, suggesting its putative role in the pathologenesis of AML. ..We thus propose to characterize this lncRNA and examine the lncRNA expression in leukemic samples. We are particularly interested in examining whether the lncRNA regulates the gene expression of RUNX1 and its fusion gene, like AML1-ETO, through an epigenetic mechanism. Using several epigenetic technologies available in the lab, including 3C (chromatin conformation capture), R3C, ChoP (Chromatin Oligo-Affinity Precipitation), and ChIP (chromatin immunoprecipitation), we will examine how the lncRNA epigenetically regulates its target genes, including the interaction of lncRNA with its target DNA sequence, the formation of the intra- and inter-chromosomal looping, and the lncRNA-mediated recruitment of chromatin modifying factors, like histone H3-K27 methylase EZH2. We will test whether these chromatin interactions are correlated with the gene expression in leukemic cells. After shRNA knockdown, we will explore if the lncRNA is involved in the chromosomal translocation and affects the leukemic stem cell renewal and chemo-resistance. This study may shed light on a novel therapeutic direction for drug discovery to treat leukemia by harnessing an epigenetic mechanism.

RUNX1是急性髓系白血病（AML）转位突变最易累及的基因之一，转位后产生的AML1-ETO融合蛋白直接参与肿瘤的发生，但转位机制不清。本课题组首次发现在RUNX1内含子区存在长链非编码RNA(lncRNA)，并证实该lncRNA同时连接参与转位的21号染色体RUNX1启动子和8号染色体的ETO基因调节序列，提示该非编码RNA在白血病发病中起重要作用：1）通过启动子调控RUNX1及AML1-ETO的表达；2）通过改变染色质空间构象参与t（8,21）转位形成。本课题拟采用新的研究染色质空间结构及lncRNA-染色质DNA结合的方法，对lncRNA结构及差异性表达进行深入分析、并探索lncRNA调控RUNX1和AML1-ETO融合基因表达的表观遗传学机制以及介导t（8,21）染色体转位的分子机制，进而揭示lncRNA在血液病恶性转化中的作用，为临床治疗及新药研究开发提供新的理论依据

RUNX1 是急性髓系白血病（AML）转位突变最易累及的基因之一，转位后产生的AML1-ETO 融合蛋白直接参与肿瘤的发生，但转位机制不清。本课题组首次发现在RUNX1 内含子区存在长链非编码RNA(lncRNA)，并证实该lncRNA 同时连接参与转位的21 号染色体RUNX1 启动子和8 号染色体的ETO 基因调节序列，提示该非编码RNA 在白血病发病中起重要作用：1）通过启动子调控RUNX1 及AML1-ETO 的表达；2）通过改变染色质空间构象参与t （8,21）转位形成。本课题通过研究证实了RUNX1的启动子区域能够转录出一条长链非编码RNA RUNXOR。在AML中，RUNXOR表达上调，并且在阿糖胞苷进行化疗的过程中亦呈现上调趋势。RUNXOR通过其3’末端与RUNX1启动子直接作用并参与启动子-增强子形成染色体内环结构，而这种内环结构能够影响RUNX1转位。本研究从分子机制和染色体结构方面揭示了lncRNA 在血液病恶性转化中的作用，为临床治疗及新药研究开发提供新的理论依据。