FoxM1过表达促进肝细胞癌的上皮-间质转化和转移。
FoxM1 overexpression promotes epithelial-mesenchymal transition and metastasis of hepatocellular carcinoma.
作者信息
Meng Fan-Di, Wei Ji-Chao, Qu Kai, Wang Zhi-Xin, Wu Qi-Fei, Tai Ming-Hui, Liu Hao-Chen, Zhang Rui-Yao, Liu Chang
机构信息
Fan-Di Meng, Ji-Chao Wei, Kai Qu, Zhi-Xin Wang, Ming-Hui Tai, Hao-Chen Liu, Rui-Yao Zhang, Chang Liu, Department of Hepatobiliary Surgery, the First Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an 710061, Shaanxi Province, China.
出版信息
World J Gastroenterol. 2015 Jan 7;21(1):196-213. doi: 10.3748/wjg.v21.i1.196.
AIM
To investigate the expression of forkhead box protein M1 (FoxM1) in the process of epithelial mesenchymal transition in hepatocellular carcinoma (HCC) and its role in metastasis.
METHODS
FoxM1 and E-cadherin expression in HCC tissue microarray specimens was evaluated by immunohistochemical staining, and statistical methods were applied to analyze the correlation between FoxM1 and epithelial-mesenchymal transition (EMT). Kaplan-Meier analysis of the correlation between the FoxM1 expression level and recurrence or overall survival of HCC patients was performed. The expression of FoxM1, E-cadherin and snail homologue 1 (SNAI1) in HCC cell lines was evaluated by real-time reverse transcription-polymerase chain reaction and Western blot. Hepatocyte growth factor (HGF) was used to induce EMT and stimulate cell migration in HCC cells. The expression of FoxM1 and SNAI1 was regulated by transfection with plasmids pcDNA3.1 and siRNAs in vitro. The occurrence of EMT was evaluated by Transwell assay, morphologic analysis and detection of the expression of EMT markers (E-cadherin and vimentin). Luciferase and chromatin immunoprecipitation assays were used to evaluate whether SNAI1 is a direct transcriptional target of FoxM1.
RESULTS
FoxM1 expression was increased significantly in HCC compared with para-carcinoma (10.7 ± 0.9 vs 8.2 ± 0.7, P < 0.05) and normal hepatic (10.7 ± 0.9 vs 2.7 ± 0.4, P < 0.05) tissues. Overexpression of FoxM1 was correlated with HCC tumor size, tumor number, macrovascular invasion and higher TNM stage, but was negatively correlated with E-cadherin expression in microarray specimens and in cell lines. FoxM1 overexpression was correlated significantly with HCC metastasis and EMT. In vitro, we found that FoxM1 plays a key role in HGF-induced EMT, and overexpression of FoxM1 could suppress E-cadherin expression and induce EMT changes, which were associated with increased HCC cell invasiveness. Next, we confirmed that FOXM1 directly binds to and activates the SNAI1 promoter, and we identified SNAI1 as a direct transcriptional target of FOXM1. Moreover, inhibiting the expression of SNAI1 significantly inhibited FoxM1-mediated EMT.
CONCLUSION
FoxM1 overexpression promotes EMT and metastasis of HCC, and SNAI1 plays a critical role in FoxM1-mediated EMT.
目的
探讨叉头框蛋白M1（FoxM1）在肝细胞癌（HCC）上皮-间质转化过程中的表达及其在转移中的作用。
方法
采用免疫组织化学染色法评估HCC组织芯片标本中FoxM1和E-钙黏蛋白的表达，并应用统计学方法分析FoxM1与上皮-间质转化（EMT）之间的相关性。对HCC患者的FoxM1表达水平与复发或总生存之间的相关性进行Kaplan-Meier分析。通过实时逆转录-聚合酶链反应和蛋白质免疫印迹法评估HCC细胞系中FoxM1、E-钙黏蛋白和蜗牛同源物1（SNAI1）的表达。使用肝细胞生长因子（HGF）诱导HCC细胞发生EMT并刺激其迁移。体外通过转染质粒pcDNA3.1和小干扰RNA（siRNA）调节FoxM1和SNAI1的表达。通过Transwell实验、形态学分析以及检测EMT标志物（E-钙黏蛋白和波形蛋白）的表达来评估EMT的发生情况。使用荧光素酶和染色质免疫沉淀实验评估SNAI1是否为FoxM1的直接转录靶点。
结果
与癌旁组织（10.7±0.9比8.2±0.7，P<0.05）和正常肝组织（10.7±0.9比2.7±0.4，P<0.05）相比，HCC组织中FoxM1表达显著增加。FoxM1过表达与HCC肿瘤大小、肿瘤数量、大血管侵犯及更高的TNM分期相关，但在组织芯片标本和细胞系中与E-钙黏蛋白表达呈负相关。FoxM1过表达与HCC转移和EMT显著相关。在体外，我们发现FoxM1在HGF诱导的EMT中起关键作用，FoxM1过表达可抑制E-钙黏蛋白表达并诱导EMT变化，这与HCC细胞侵袭性增加相关。接下来，我们证实FOXM1直接结合并激活SNAI1启动子，并确定SNAI1为FOXM1的直接转录靶点。此外，抑制SNAI1表达可显著抑制FoxM1介导的EMT。
结论
FoxM1过表达促进HCC的EMT和转移，SNAI1在FoxM1介导的EMT中起关键作用。
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