FoxM1c-miR-149-FoxM1b/1c负反馈环路在结肠癌血管生成中的调控作用及分子机制研究

靶基因-miRNA交互调控参与人多种生理和病理过程，其在结肠癌血管生成中的作用有待深入探索。本课题组前期已报道：转录因子叉头框蛋白M1(forkhead box M1,FoxM1)促进结肠癌增殖、侵袭和转移等恶性表型形成，并受miR-149负向调控。然而，FoxM1在结肠癌血管生成中的作用及分子机制并不清楚。课题组预实验发现：FoxM1与结肠癌组织微血管密度、VEGF和MMP-2表达正相关；软件分析显示miR-149核心启动子区含两个FoxM1c结合位点而没有FoxM1b结合位点。基于此，我们提出科学假说：FoxM1c-miR-149-FoxM1b/1c负反馈环路可能是结肠癌血管生成的重要分子机制。本研究拟采用位点突变、免疫共沉淀、基因过表达及RNA干扰等技术，分别从细胞和活体动物水平深入阐明上述负反馈环路在结肠癌血管生成中的作用和分子机制，为进一步筛选和开发抗血管治疗新靶标提供理论依据。

The cross-regulation between target genes and microRNA is involved in many human physiological and pathological processes, whereas its roles in colon cancer angiogenesis remain further exploration. As we reported, the up-regulation of transcription factor forkhead box M1 (FoxM1) promoted the formation of malignant phenotypes of proliferation, invasion and metastasis in colon cancer, which was negatively regulated by miR-149. However, the functions and related molecular mechanisms of FoxM1 in colon cancer angiogenesis are still unclear. Our team has found out that the level of FoxM1 positively correlates with those of microvessel density, VEGF and MMP-2 in cancer tissues, and that two potential FoxM1c-binding but not FoxM1b-binding sites exist in the core promoter region of miR-149 by bioinformatics softwares. Therefore, a scientific hypothesis is raised that a negative feedback loop of FoxM1c-miR-149-FoxM1b/1c should play key roles in colon cancer angiogenesis. In this study, many techniques including site mutation, chromatin immunoprecipitation, gene over-expression and RNA interference are to be used in cultured cell lines and small live animal models, respectively, to deep elucidate the roles and molecular mechanisms of the mentioned negative feed back loop. Our study may help to provide theoretical evidences for further screening and developing novel therapeutic anti-angiogenesis targets against colon cancer.