转录因子FOXM1调控乳腺癌细胞干性的机制研究

To study gene regulatory mechanisms of tumor stem cells and identify therapeutic targets for abolishing the stemness of cancer cells will help us to develop cancer treatment strategies in clinical practice. Our previous studies have shown that transcription factor FOXM1 correlates with tumorigenesis and progression of many cancers, and is one of the key factors participating in the regulation of tumor stem cells. In this proposal, we intend to infect breast cancer cells with a lentivirus (Lv-PromoterFOXM1-EGFP) that produces the Green Fluorescent Protein in the cells as a tracing mark of FOXM1 expression. The FOXM1+ cell subpopulation can be isolated by cell sorting. The usage of adherent culture condition will force the FOXM1+ cells, which possess the characteristics of tumor stem cells, to differentiate to a FOXM1- cell subpopulation with heterogeneous non-stem cancer cells. These two cell subpopulations provide us good cell models to study mechanisms of breast cancer cell stemness maintained by FOXM1. We will identify the target genes of FOXM1, find co-factors that interact with FOXM1, and study the crosstalk among FOXM1 and its co-factors on gene expression regulation in breast cancer stem cells. We will test whether FOXM1 can be used as a marker and its levels can predict the stemness and malignancy of clinical breast cancers. Furthermore, we will try to develop a protein therapeutic reagent to abolish the stemness of breast cancer cell through inhibiting FOXM1 functions. Overall, this study will expand our knowledge in tumor stem cells by confirming the roles of FOXM1 in maintaining the stemness of breast cancer stem cells, and provide a foundation for the development of FOXM1-related strategies for breast cancer diagnosis and treatment.

认识肿瘤干细胞的调控机制并确认抑制其特性的治疗靶点，对肿瘤临床治疗具有重要意义。前期工作表明，转录因子FOXM1与肿瘤发生发展密切相关，是乳腺癌干细胞中的关键调控因子。本项目将用Lv-PromoterFOXM1-EGFP慢病毒感染乳腺癌细胞，示踪FOXM1的表达，分选获得具有肿瘤干细胞特征的FOXM1+ 细胞亚群，贴壁培养后得到分化细胞亚群，作为研究FOXM1维持肿瘤干性的模型。通过本研究：1，鉴定肿瘤干细胞中FOXM1所调控的靶基因；2，确定肿瘤干细胞中FOXM1的互作蛋白及其作用机制；3，以FOXM1作为标志物预测临床乳腺癌干性和恶性程度；4，以FOXM1作为靶标开发抑制乳腺癌细胞干性的蛋白类药物。本研究将拓展对肿瘤干细胞本质的认识，从基因表达调控的分子机制层面，阐明FOXM1维持乳腺癌干细胞干性的作用机制，为FOXM1作为乳腺癌干性标志物和治疗靶标提供理论依据和试验基础。

肿瘤干细胞对肿瘤的存活、增殖、转移及复发有着重要影响，认识肿瘤干细胞的调控机制并确认抑制其特性的治疗靶点，对肿瘤临床治疗具有重要意义。基因表达调控在肿瘤干细胞中发挥了关键作用，研究乳腺癌干细胞中特定转录因子调节干性相关基因的分子机制，对认识乳腺癌干细胞的调控机制并确认抑制靶点具有重要价值。本项目运用Lv-PromoterFOXM1-EGFP慢病毒感染乳腺癌细胞，示踪FOXM1的表达，分选获得具有肿瘤干细胞特征的FOXM1+细胞亚群，作为研究FOXM1维持肿瘤干性的细胞模型。通过鉴定肿瘤干细胞中FOXM1所调控的靶基因、确定FOXM1的互作蛋白及其作用机制、以FOXM1作为靶标开发抑制乳腺癌细胞干性的多肽药物等研究工作，拓展对肿瘤干细胞本质的认识。本项目取得的成果包括：1，FOXM1调控乳腺癌干细胞基因表达的作用机制。2，FOXM1与其互作蛋白共同调控并决定肿瘤干细胞基因表达。3，FOXM1作为标志物预测临床乳腺癌干性和恶性程度。4，获得多个抑制 FOXM1的多肽蛋白原药。相关成果从基因表达调控的分子机制层面，阐明了FOXM1维持乳腺癌干细胞干性的作用机制，为FOXM1作为乳腺癌干性标志物和治疗靶标提供理论依据和试验基础。通过开展FOX转录因子家族其他成员的相关研究，本项目取得的成果还包括：1，首次发现FOXM1选择染色质DNA特定片段加载进细胞外囊泡，被受体细胞吸收并与受体细胞基因组整合。2，FOXP2抑制乳腺癌细胞上皮间质转化。3，FOXA1诱导三阴乳腺癌细胞凋亡并抑制细胞周期。本项目所获成果，深化对FOX家族转录因子参与乳腺癌干性、凋亡等表型调控的认识，确认乳腺癌的新治疗靶点，为乳腺癌临床诊断和治疗提供新思路。相关成果已发表高水平SCI论文（IF>5）2篇，BioRxiv预印本论文1篇，中文核心期刊论文1篇，待发表论文4篇。授权发明专利3项，公开发明专利1项。毕业研究生15名，其中博士2名，硕士13名。项目经费严格按相关规定支出使用，无经费结余。