miR-744失调在非小细胞肺癌侵袭转移中的作用和调控机制

Currently the role of miR-744 in tumor is seldom studied, and the relation between miR-744 and non-small cell lung cancer (NSCLC) or metastasis is even undocumented. Our previous studies revealed that miR-744 was upregulated in NSCLC tissues and serum and indicated adverse prognosis. Moreover, miR-744 could promote the migration and invasion ability of NSCLC cells. Based on Gene chip analysis, bioinformatic analyses and preliminary experiments, we proposed a novel mechanism underlying the dysregulation of miR-744 and its role. That is, miR-744 is direct transcriptional targets of c-Jun or CDX2 which binds to the promoter of miR-744, thereby enhances cell invasion and metastasis by directly targeting the promoters of the proto-oncogenes, like FOS, in NSCLC. To test the hypothesis, firstly, we will explore the oncogenic roles of miR-744 in NSCLC by mouse xenograft model. secondly, we will valid the mechanism underlying the upregulation of miR-744 by transcriptor c-Jun or CDX2, as well as the direct interaction between miR-744 and the promoters of proto-oncogenes in NSCLC invasion and metastasis using ChIP，promoter luciferase reporter and site-directed mutagenesis. Last but not least, the clinic implications of miR-744 and its related moleculars will be identified in NSCLC tissues and serum samples, as well as by network data mining. This work may ultimately yield further insight into the function of miR-744 and the molecular mechanisms of metastasis of NSCLC. New targets for the clinical intervention of metastasis of NSCLC may be disclosed.

目前有关miR-744在肿瘤领域的研究为数不多，与非小细胞肺癌（NSCLC）及转移的关系尚未见报道。我们发现miR-744在NSCLC组织血清中表达上调，与不良预后相关，能促进肺癌细胞侵袭迁移。根据基因芯片、生物信息学分析及预实验结果，我们提出一个新的miR-744失调及作用机制：转录因子c-Jun或CDX2结合至miR-744启动子上调其表达，miR-744亦通过靶向启动子正向调节FOS等促癌基因促进NSCLC侵袭转移。为此，本项目拟通过体内外实验确证miR-744在NSCLC中的促癌性；其次利用ChIP、启动子荧光素酶报告系统、定点突变等技术验证c-Jun或CDX2作为转录因子上调miR-744的机制，以及miR-744靶向FOS等促癌基因参与肺癌侵袭转移的机制；最后扩大临床样本检测结合网络数据挖掘明确miR-744及其上下游分子预警肺癌进展转移、判断预后方面的作用。

目前有关miR-744在肿瘤领域的研究为数不多，与非小细胞肺癌（NSCLC）及转移的关系尚未见报道。首先，通过临床样本检测、网络数据挖掘及结合体外、体内实验明确miR-744在肺癌侵袭转移中的作用，发现miR-744在NSCLC组织中表达上调，与不良预后相关，能促进肺癌细胞侵袭迁移、体内皮下成瘤和转移，干扰miR-744可提高肺癌细胞的药物敏感性和放疗敏感性。其次，通过生物信息学预测并用双荧光素酶报告基因系统，验证了miR-744通过直接靶向c-FOS启动子促进其转录从而促进肺癌细胞迁移和侵袭；最后，通过ChIP、启动子荧光素酶报告系统、定点突变等技术对调控miR-744转录关键转录因子的鉴定，首次证明了c-Jun可作为转录因子与miR-744启动子序列-343~-349bp结合并上调其表达，进而显著促进NSCLC细胞增殖及迁移侵袭。综上所述，我们提出一个新的miR-744失调及作用机制：转录因子c-Jun结合至miR-744启动子上调其表达，miR-744 亦通过靶向启动子正向调节c-FOS等促癌基因促进NSCLC侵袭转移，为 miR-744 成为可能的、新的肺癌诊断预后标志物及治疗靶点提供了理论和实验基础，为进一步寻找新的肺癌治疗靶点提供思路和方向。