叉头框蛋白M1(FOXM1)通过转录激活存活素(survivin)基因表达而参与结肠癌肝转移表型形成的分子机制研究

The liver is the most common site of distant metastasis from colorectal cancer(CRC), and this process may be associated with expression of metastatic related proteins and their regulation. FOXM1(Forkhead box protein M1)belongs to a large family of forkhead box(Fox)transcription factors. Previous studies show that the status of FOXM1 expression in CRC tissues is significantly correlated with clinical stage, lymph node metatasis and prognosis of patients with CRC, but the roles of FOXM1 in liver matastasis of CRC and the mechanisms of its transcriptional regulation are still unclear. On the basis of past successful selection of transcription factor microarray asscociated with liver metastsis of CRC, the aim of this study is to investigate the correlation of FOXM1 expression with liver metastasis of CRC at both celluar level and animal level. By luciferase reporter, gel retardation, co-immunoprecipitation, RNA interference and gene-overexpression assays, we next further explore the molecular mechanisms of FOXM1 promoting the liver metastasis of CRC by ativation of survivin at the transcriptional level, which will provide a novel molecular target for the treatment of human CRC.

结肠癌肝转移是结肠癌最常见的转移类型，其形成过程涉及肿瘤转移相关蛋白基因表达及其调控的各个过程。FOXM1是叉头框转录因子家族重要成员之一，本课题组前期研究结果表明：结肠癌组织中FOXM1基因表达水平与患者临床分期、淋巴结转移状况及预后密切相关，但是其在结肠癌肝转移表型形成过程中的作用及其转录调控机制仍不清楚。在前期成功筛选结肠癌肝转移相关转录因子差异表达谱及生物信息学分析的基础上，本课题拟从细胞和活体动物水平进行FOXM1与结肠癌肝转移表型形成相关的功能学分析，并通过荧光素酶报告基因、凝胶阻滞、免疫共沉淀、位点突变、RNA干涉及基因过表达等试验技术探讨FOXM1基因通过转录水平激活survivin基因的表达参与结肠肝转移表型形成的分子机制，从而为临床个体化治疗结肠癌肝转移提供准确的分子靶标。

结肠癌病死率居世界第三位，结肠癌转移是结肠癌致死的主要原因。转移性结肠癌的主要治疗手段为化疗，而化疗耐药是临床治疗面临的巨大挑战。因此，阐明结肠癌转移、耐药的机制具有重要意义。本项目研究发现：（1）miR-149在结肠癌肿瘤组织中低表达，其表达与结肠癌淋巴结转移、远处转移呈负相关，进一步功能与机制研究表明，miR-149通过靶向FOXM1抑制结肠癌侵袭转移；（2）经基因芯片分析与后续验证，提示PHF5A是FOXM1下游调控的新的靶基因，过表达PHF5A能够促进结肠癌细胞的增殖、迁移和侵袭；（3）在化疗耐药方面，特别是5-FU耐药，miR-149在5-FU耐药结肠癌细胞中低表达，过表达miR-149通过靶向FOXM1促进了结肠癌对5-FU的化疗敏感性；（4）基因芯片结果显示FOXM1在5-FU不敏感的结肠癌患者中高表达，抑制FOXM1的表达可增强耐药细胞对5-FU的化疗敏感性，进一步体内外实验证实ABCC10介导了FOXM1引起的5-FU耐药，抑制FOXM1/ABCC10轴能够逆转5-FU耐药。.我们的研究结果阐明了FOXM1在结肠癌转移、5-FU耐药中的作用及机制，为结肠癌转移、化疗耐药提供了新的治疗靶点。本项目研究成果已发表SCI论文5篇，其中影响因子5.0以上1篇，发表中文核心期刊2篇；参加国内学术交流一次，获大会优秀论文；培养硕士研究生3名。