miR-181a在常见儿童恶性肿瘤中的表达、功能及调控机制研究

Recent studies demonstrated that microRNA could either promote or suppress tumorigenesis. We recently found that miR-181a is elevated significantly in pediatric leukemia and promotes the proliferation of leukemia cells. It is known that miR-181a gene located on chromosome fragile sites and abnormal expression of miR-181a is reported in a variety of cancers. We therefore hypothesize that miR-181a plays an important role in tumorigenesis and novel miR-181a target genes mediate such an activity. In the proposed study, we will determine the miR-181a expression in common childhood malignancy (leukemia, glioma, neuroblastoma and lymphoma) and its correlation with the phenotypic parameters(i.e.tumortype,clinical presenta- tion, progression and prognosis). Further, we propose to establish a stable cell lines with higher or lower level of miR-181a and use them to study the biological roles of miR-181a, such as its effects on cell proliferation, differentiation and apoptosis. These cells will aslo be further investigated in vivo by xenograft studies using SICD mice. To explore the mechanism, we will identify the miR-181a target genes by combining the bioinformatic analyses and experimental validation. The completion of the proposed study will be expected to reveal the function and mechanism of miR-181a and its role in childhood malignancy. Besides to define the "RNA regulatory network" of miR-181a, the miR-181a target gene uncovered in our study could provide novel molecular targets as biomarkers for diognosis and /or targets for cancer therapy.

近年来发现许多小RNA在肿瘤发生中起着"癌基因"或"抑癌基因"作用。本课题组前期研究表明：miR-181a在儿童白血病中高表达，并可促进白血病细胞增殖。通过文献检索，miR-181a基因位于染色体脆性位点，且在多种肿瘤中表达异常。因此，提出如下假说：miR-181a在多种肿瘤发生中起着重要作用，它通过作用于多个靶基因，导致肿瘤发生。本项目拟检测miR-181a在常见儿童恶性肿瘤（白血病、神经胶质瘤、神经母细胞瘤及淋巴瘤）中的表达，并分析它与肿瘤分类、分型、临床表现以及预后的相关性。对其异常表达的肿瘤，进一步建立稳定高或低表达miR-181a肿瘤细胞系，通过细胞水平和SCID小鼠体内研究其对肿瘤细胞增殖、分化及凋亡的影响，并筛选及验证其靶基因。本项目的完成将阐明miR-181a在常见儿童恶性肿瘤中的表达、功能及调控机理，不仅对揭示"RNA调控网络"具有重要意义，而且可能为肿瘤治疗提供新的靶点

研究背景：近年来发现许多小 RNA 在肿瘤发生中起着"癌基因"或"抑癌基因"作用。本课题组前期研究表明： miR-181a 在儿童白血病中高表达，并可促进白血病细胞增殖。通过文献检索， miR-181a 基因位于染色体脆性位点，且在多种肿瘤中表达异常。因此，提出如下假说：miR-181a 在多种肿瘤发生中起着重要作用，它通过作用于多个靶基因，导致肿瘤发生。.研究内容：本项目检测了 miR-181a 在常见儿童恶性肿瘤（白血病、神经胶质瘤、神经母细胞瘤及淋巴瘤）中的表达，并分析它与肿瘤分类、分型、临床表现以及预后的相关性。并对其异常表达的肿瘤，进一步建立了稳定高和低表达 miR-181a 肿瘤细胞系， 通过细胞水平和 SCID 小鼠体内研究其对肿瘤细胞增殖、分化及凋亡的影响，并筛选及验证了其靶基因。.重要结果：miR-181a在多种白血病细胞系（NB4、HL-60、K562）及神经母细胞瘤标本中高表达，且高表达miR-181a可以促进白血病及神经母细胞瘤细胞增殖；高表达的miR-181a促进AM与NBL的细胞增殖，细胞周期转变，从G0/G1期向S及G2期转变；miR-181a 靶向ATM基因，并可能是通过调控ATM 转录水平抑制蛋白表达；miR-181a在神经母细胞瘤中的表达与肿瘤分期无明显相关性；过表达miR-181a能够增强NB细胞的侵袭能力，反之，抑制miR-181a表达减弱NB细胞的侵袭能力。.科学意义：本项目的完成阐明了 miR-181a在常见儿童恶性肿瘤中的表达、功能及调控机理，不仅对揭示"RNA 调控网络"具有重要意义，而且可能为肿瘤治疗提供新的靶点。

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