Klf4调控FoxM1在胃癌发病中的作用

Gastric cancer is the third most common cancer in our country. Our previous experiments have established the critical relationship between gastric cancer development, invasion and the loss of Klf4 and/or over-expression of FoxM1. Klf4 is the negative regulator of FoxM1 by combining the promoter of FoxM1. But it was reported that s Gli1 is the positive regulator of FoxM1. Tofurther study the effect of Klf4 on modulating FoxM1 which directly promotes gastric epithelial cells carcinogenesis and interaction between KLF4 and Gli1 in the regulation of FoxM1 transcription, We firstly knockdown Klf4 from gastric mucosal cell line, GSM06 and then assess its FoxM1 expression and epigenetic change. Those can help us to find out the relationship between Klf4 regulator foxM1 and gastric carcinogenesis. Then we will clone series of FoxM1 promoter including the overlapping part of Klf4 and FoxM1with the methods of point mutation. By the way of overexpression of Klf4 and/or Gli1 and the methods of ChIP, EMSA, promoter assay, we can find out how Klf4 and Gli1 competently combine the promoter of FoxM1 to regulate FoxM1. All those can help us to determine the key role of Klf4 and FoxM1 on gastric cancer progression.

胃癌发病率和死亡率均高居我国肿瘤发病与死亡的前三位。我们的前期研究表明Klf4的缺失以及FoxM1的过表达与胃癌的发病及侵袭、转移密切相关，Klf4通过与FoxM1启动子部分结合而负性调控FoxM1，文献则报告Gli1是FoxM1的正向调控因子。为了进一步研究Klf4调控FoxM1在胃粘膜上皮细胞恶性变中的作用以及Klf4与Gli1是如何相互作用调控FoxM1，我们将正常胃粘膜细胞系GSM05中的Klf4敲除观察其FoxM1的表达及其恶性表型的改变，以明确Klf4调控FoxM1与胃癌发病的关系。同时我们采用点突变技术克隆系列FoxM1启动子上的Klf4与Gli1的互有重叠的启动子部分，通过过表达Klf4和/或Gli1并采用ChIP、EMSA和启动子分析技术探讨Klf4与Gli1竞争结合FoxM1启动子而发挥调控FoxM1的机制。为阐明Klf4与FoxM1在胃癌发病机制中的关键作用提供证据。

胃癌的侵袭与转移是其预后差的主要因素，在我国，胃癌发病率和死亡率均高居肿瘤发病与死亡的前三位。已知Klf4是包括胃癌在内的多种恶性肿瘤的主要抑癌基因，胃癌组织中Klf4的表达与胃癌预后明显相关。FoxM1则是目前已知最重要的促进癌细胞增殖和转移的癌基因，在胃癌组织中显著高表达。本项目通过一系列细胞功能学实验，动物实验，分子生物学手段和临床样本分析，阐明了Klf4通过抑制FoxM1表达进而抑制胃癌发生的机制。具体地，我们证明了KLF4的低表达与FoxM1高表达密切相关，功能实验也表明FoxM1在Klf4的下游促进胃癌细胞增殖，迁移和细胞周期进展。机制上，Klf4结合在FoxM1启动子上转录抑制FoxM1表达，同时Klf4还和Gli1存在竞争性关系，我们通过采用ChIP实验和启动子分析技术深度探讨了Klf4 与Gli1 竞争结合FoxM1 启动子而发挥调控FoxM1转录的机制。本项目的研究为阐明Klf4 与FoxM1 在胃癌发病机制中的关键作用提供证据，也为以此为依据发展和设计胃癌治疗药物提供了帮助。