Objective: To investigate the expression of Nanog and its regulatory relationship with MMP-2/MMP-9 proteins in esophageal squamous cell carcinoma (ESCC).
Methods: We detected Nanog and MMP-2/MMP-9 protein expressions in 127 ESCC tissues and 82 adjacent normal tissues using immunohistochemistry and explored their correlations with the clinicopathological parameters and prognosis of the patients. GEO database was utilized to analyze the pathways enriched with the stemness-related molecules including Nanog, and TIMER online tool was used to analyze the correlations among TβR1, MMP-2, and MMP-9 in esophageal cancer.
Results: Nanog and MMP-2/MMP-9 proteins were significantly upregulated in ESCC tissues and positively intercorrelated. Their expression levels were closely correlated with infiltration depth and lymph node metastasis of ESCC but not with age, gender, or tumor differentiation. The patients with high expressions of Nanog and MMP-2/MMP-9 had significantly shorter survival time. Bioinformatics analysis showed enrichment of stemness-associated molecules in the TGF-β signaling pathway, and the expressions of MMP-2/MMP-9 and TβR1 were positively correlated. In cultured ESCC cells, Nanog knockdown significantly decreased the expression of TβR1, p-Smad2/3, MMP-2, and MMP-9 and strongly inhibited cell migration.
Conclusion: The high expressions of Nanog, MMP-2, and MMP-9, which are positively correlated, are closely related with invasion depth, lymph node metastasis, and prognosis of ESCC. Nanog regulates the expressions of MMP-2/MMP-9 proteins through the TGF-β signaling pathway, and its high expression promotes migration of ESCC cells.
目的: 探讨食管鳞状细胞癌（鳞癌）中干性相关分子胚胎干细胞关键因子（Nanog）和侵袭迁移相关分子基质金属蛋白酶-2（MMP-2）、基质金属蛋白酶-9（MMP-9）蛋白的表达及其之间的调控关系。
方法: 运用免疫组织化学技术检测127例食管鳞癌组织和82例癌旁正常组织中Nanog和MMP-2/MMP-9蛋白的表达情况，分析Nanog和MMP-2/MMP-9蛋白的表达水平、相关性及与食管鳞癌患者的临床病理参数和预后之间的关系；采用GEO数据库分析Nanog等干性相关分子主要富集通路；应用TIMER在线网站分析食管癌中TβR1和MMP-2及MMP-9的相关性。在体外运用siRNA转染的方式将食管鳞癌细胞株分为正常对照组、Nanog低表达组，采用划痕实验分析其对食管鳞癌细胞迁移的影响，qRT-PCR及Western blotting检测两组之间TβR1、p-Smad2/3、MMP-2/MMP-9的表达情况。
结果: Nanog和MMP-2/MMP-9蛋白在食管鳞癌组织中表达均上调（χ2=70.475，P<0.01；χ2=34.415，P<0.01；χ2=46.605，P<0.01），且呈正相关（r=0.205，P=0.045；r=0.307，P<0.001）。Nanog和MMP-2/MMP-9蛋白表达水平与食管鳞癌的浸润深度相关（χ2=23.9，P<0.01；χ2=6.029，P<0.05；χ2=11.89，P<0.05），有淋巴结转移的样本中，MMP-2/MMP-9蛋白表达水平高于无淋巴结转移的样本（χ2=10.08，P<0.01；χ2=5.731，P<0.05）。MMP-2/MMP-9蛋白表达与食管鳞癌患者的年龄、性别和肿瘤分化程度无相关性（P>0.05）。Kaplan-Meier生存分析显示，Nanog和MMP-2/MMP-9蛋白高表达组的食管鳞癌患者生存时间短于低表达组（P<0.001；P=0.004；P=0.017）；生物信息学分析显示，Nanog等干性相关分子主要富集在转化生长因子-β（TGF-β）信号通路，MMP-2/MMP-9与TβR1表达在食管癌中呈正相关关系。体外划痕实验结果显示，Nanog促进食管鳞癌细胞系的迁移；qRT-PCR及Western blotting结果显示，敲低Nanog后，TβR1、p-Smad2/3、MMP-2/MMP-9的表达水平明显降低。
结论: Nanog和MMP-2/MMP-9蛋白在食管鳞癌患者组织中高表达且呈正相关，其与食管鳞癌患者的肿瘤浸润深度、淋巴结转移及预后密切相关，且Nanog通过TGF-β信号通路影响MMP-2/MMP-9蛋白的表达。
Keywords: MMP-2/MMP-9; Nanog; esophageal squamous cell carcinoma; infiltration and metastasis; survival analysis.