NF-κB信号通路在食管鳞癌细胞系中的激活

The Activation of NF-κB Signaling Transduction Pathway in Esophageal Squamous Cell Carcinoma Cell Lines

目的核转录因子NF-kappaB(NF-κB)是一种重要的转录因子,参与调控多种与炎症、抗凋亡、肿瘤形成和转化有关的基因表达。本研究拟通过检测NF-κB信号通路在食管鳞癌细胞系中是否存在,分析NF-κB在食管鳞癌细胞中的激活状态及其对食管鳞癌细胞的生存及转化作用。方法采用免疫细胞化学法和Western blotting法检测两株食管鳞癌细胞系中NF-κB亚单位p50和p65,阻遏物IκBα及其上游激酶IKKβ的蛋白表达。并采用EMSA法检测两株食管鳞癌细胞核中NF-κB与DNA的结合活性。结果食管鳞癌细胞中存在激活的NF-κB信号通路,p50、p65、IκBα及其上游激酶IKKβ的蛋白在细胞质中均表达,并且p50/p65在细胞核中具有较高的DNA结合活性。结论本研究发现NF-κB信号通路在两种食管鳞癌细胞系被激活,提示激活的NF-κB信号通路可能在食管鳞癌发生中起重要作用。

Objective More and more evidences have shown that transcription factor Nuclear Factor-kappaB （NF-kB） plays a critical role in the initiation and progression of carcinogenesis. In the present study, we investigated whether the NF-kB signaling transduction pathway was constitutively activated in ESCC cell lines. Methods Immunocytochemistry and Western blotting were used to determine the protein levels of the subunits of NF-kB,p50 and p65, inhibitor-xBα and IKKβ in two ESCC cell lines. Nuclear proteins from the ESCC cell lines were extracted to evaluate the DNA-binding activity by electrophoretic mobility gel shift assay （EMSA）. Results Immunocytochemical analysis showed that p50 and p65, two representative subunits of NF-kB, IxBα, a natural inhibitor of NF-kB, and its upstream kinase IKKβ were mainly expressed and localized in the cytoplasm. Cytoplasm protein extracts from the cell lines each were analyzed by Western blotting. The results revealed that there was the same high NF-kB activity in the cytoplasm in two ESCC cell lines compared to that of the positive control cell line. In addition, the results of EMSA analysis for nuclear protein extract showed high DNA-binding activity of p50 and p65. Conclusion The findings demonstrate that NF-kB signaling transduction pathway is constitutively activated in human ESCC cell lines, suggesting that NF-kB may play a critical role in carcinogenesis of the esophagus.