叉头框转录因子M1蛋白在食管鳞癌细胞和组织中的表达及意义

Expression and significance of FoxM1 in esophageal squamous cell carcinoma cells in vitro and in vivo

目的探讨叉头框转录因子M1（FoxM1）蛋白在食管鳞癌细胞和组织中的表达及意义。方法采用Westernblot法检测正常食管上皮细胞（HEEC）以及食管鳞癌细胞（TE1、TE10、TE11和Eca109）中FoxM1蛋白的表达。通过RNA干扰技术敲低食管鳞癌TE1细胞中FoxM1蛋白的表达，采用四甲基偶氮唑蓝法、划痕实验及Transwell侵袭实验检测敲低FoxM1蛋白表达对TE1细胞增殖、迁移和侵袭的影响。建立裸鼠移植瘤模型，观察敲低FoxM1蛋白表达对移植瘤生长的影响。采用免疫组化法检测99例食管鳞癌组织及其癌旁组织中FoxM1蛋白的表达，分析FoxM1蛋白的表达与食管鳞癌患者临床病理特征及预后之间的关系。结果正常食管上皮细胞中几乎检测不到FoxM1蛋白，而4种食管鳞癌细胞株中FoxM1蛋白均过表达，其中TE1细胞中FoxM1蛋白表达强度最高。敲低TE1细胞中FoxM1蛋白的表达可明显抑制TE1细胞的生长、迁移和侵袭能力；并使裸鼠的成瘤能力降低，接种后35d，干扰组和阴性对照组裸鼠移植瘤的肿瘤体积分别为（1．17±0．30）cm3和（2．32±0．18）cm3，差异有统计学意义（P〈0．01）；肿瘤重量分别为（0．36±0．05）g和（1．07±0．07）g，差异亦有统计学意义（P〈0．05）。FoxM1蛋白在99例食管鳞癌组织和癌旁组织中的阳性表达率分别为61．6％（61／99）和24．2％（24／99），FoxM1蛋白在肿瘤组织中的阳性表达率明显高于癌旁组织（P〈0．05）。FoxM1蛋白在食管鳞癌组织中的表达与淋巴结转移、临床分期和浸润深度有关（均P〈0．05）。38例FoxM1蛋白阴性表达组患者的中位生存时间为42．3个月，61例FoxM1蛋白阳性表达组患者的中位生存时间为33．0个月，差异有统计学意义（P=0．036）。结论FoxM1蛋白在食管鳞癌细胞和组织中高表达，其表达水平与食管鳞癌的发生、发展及预后关系密切。FoxM1可作为食管鳞癌预后的指标和潜在的治疗靶点。

Objective To investigate the expression and significance of FoxM1 in esophageal squamous cell carcinoma （ESCC） cell lines and tissues. Methods Western blot assay was used to detect the expression of FoxM1 in human esophageal epithelial cells and esophageal squamous cell cancer cell lines TEl, TE10, TEll and Eca109 cells. To determine whether down-regulation of FoxM1 expression could inhibit the aggressive phenotype of ESCC cells, we knocked down the expression of FoxM 1 by using FoxM 1- shRNA in TEl cells. Then we detected the cell proliferation, migration and invasion of TEl cells by MTT assay, scratch assay and transwell assay. Furthermore, the effect of FoxM1 knockdown on tumorigenicity in nude mice was evaluated. Finally, immunohistochemical staining was used to detect the expression of FoxM1 in 99 cases of ESCC tissues and adjacent normal esophageal tissues. X2 test was used to analyze the correlations between the expression of FoxM1 and clinicopathologic characteristics and prognosis of ESCC patients. Results Western blot data showed that FoxM1 expression was lower in normal esophageal epithelial cells and highly expressed in four esophageal cancer cell lines, especially in TE 1 cells. Knockdown of FoxM1 inhibited the growth, invasion and migration of TEl cells and reduced their tumorigenicity in nude mice.The positive expression rate of FoxM1 in ESCC was 61.6% （61/99）, significantly higher than that in the paired adjacent normal tissues （24.2%, 24/99） （P〈0.05）. The positive expression rate of FoxM1 in ESCC tissues was 61.6% （61/99） , significantly higher than that in the paired adjacent normal tissues （24.2%, 24/99） （P〈0.05）. FoxM1 expression was significantly and positively correlated with lymph node metastasis, clinical stage and invasive depth （P 〈 0.05 ）. The median survival time was 42.3 months in 38 cases of patients with negative FoxM1 expression, and 33.0 months in 61 cases of positive FoxM1 expression, and the difference was statistically significant （P= 0.036）. Conclusions FoxM1 is highly expressed in ESCC, and significantly correlated with the initiation, development and prognosis of esophageal cancer. FOXM1 might be an indicator to predict the prognosis and serve as a potential target for therapy in esophageal cancer.