HMGA2是与结肠癌侵袭转移密切相关的重要转录因子。我们前期研究发现高表达HMGA2能使结肠癌细胞侵袭转移能力显著增强，并影响EMT相关分子表达；软件分析表明肿瘤转移关键分子miR-205启动子区域存在多个HMGA2结合位点，luciferase assay和realtime PCR证实HMGA2能使miR-205的转录活性和表达水平显著降低；我们还发现在SMAD4的3'UTR区域存在高度保守的miR-205结合位点。本项目拟在此基础上，通过构建一系列体内外模型进一步阐明HMGA2能够促进结肠癌细胞的侵袭转移；采用ChIP、EMSA、定点突变、蛋白截短实验等方法证明HMGA2能与miR-205启动子区域直接结合并下调其转录，明确两者的结合位点；揭示miR-205参与调控下游SMAD4的分子机制。本课题将为临床以HMGA2-miR-205-SMAD4为基础进行靶向治疗提供实验基础和理论依据。

As a transcriptional factor, HMGA2 plays a very important role in invasion and metastasis of colon cancer. We previously found that overexpression of HMGA2 could promote cell invasion and cause dyregulation of EMT markers in colon cancer. Computer analysis revealed that there were multiple HMGA2 AT binding domains in the promoter of miR-205, and significant reduction in expression and luciferase activity of miR-205 were noted when HMGA2 was overexpressed. Morever, we also found that there was a binding site of miR-205 which was highly conservative existing in the 3'UTR of SMAD4. Based on these findings, we want to explore the function and mechanism of HMGA2 in the regulation of invasion and metastasis via miR-205 in colon cancer. Firstly, a series of models in vitro and in vivo will be set up to explore the role of HMGA2 in colon cancer. Secondly, the direct binding between HMGA2 protein and the promoter of miR-205 will be explored. A lot of technologies will be used, such as ChIP, EMSA, luciferase analysis, point mutation assay, et al. Thirdly, the regulatory mechanism between miR-205 and SMAD4 is to be elucidated. In conclusion, this project will provide theoretic evidence for the novel diagnosis and therapy targeted at HMGA2-miR-205-SMAD4 signaling pathway in colon cancer.