Axin过表达下调β-catenin和TCF-4表达并抑制肺癌BE1细胞的增殖和侵袭

Transfection of Axin Gene Down-regulates Expressions of β-catenin and TCF-4 and Inhibits the Proliferation and Invasive Ability of Lung Cancer Cells

背景与目的Axin是Wnt通路的重要负性调节因子,其低表达和β-catenin、TCF-4的高表达与多种肿瘤有关。本研究旨在探讨axin在肺癌细胞中的表达与β-catenin和TCF-4的关系,及其对肺癌细胞增殖、凋亡和侵袭能力的影响。方法将axin基因转染入axin低表达的肺癌BE1细胞系,应用免疫荧光方法观察转染组和对照组细胞中axin的表达对β-catenin和TCF-4的影响;采用RT-PCR方法检测axin和β-catenin、TCF-4mRNA表达的变化;采用流式细胞术、MTT和Transwell检测肺癌细胞凋亡、增殖和侵袭能力的变化。结果肺癌BE1细胞转染axin基因后(BE1-axin),axin的mRNA和蛋白水平均明显增加,β-catenin蛋白表达明显减少,TCF-4的蛋白和mRNA表达均明显下降。同时,BE1-axin细胞的凋亡率增加,增殖和侵袭能力明显下降。结论Axin过表达能下调β-catenin的蛋白表达和TCF-4的转录,抑制肺癌细胞的增殖和侵袭能力,并诱导肺癌细胞凋亡。

Background and objective Axin is an important negative regulator of Wnt signaling pathway. It can induce the phosphorylation and degradation of β-catenin. The reduced expression of axin or high expression of β-catenin and TCF-4 were associated with malignant proliferation in many tumors. The aim of this study is to examine the relationships among the expressions and locations of axin, β-catenin and other relevant molecules, and the roles of axin on proliferation, invasive ability and apoptosis of lung cancer cells. Methods The axin cDNA was transfeeted into lung cancer BE1 cell line which has very low axin expression. The levels of expression and location of axin, β-eatenin and TCF-4 before and after transfection were detected using immunofluorescence. The mRNA levels of expression of axin, β-catenin and TCF-4 were examined using reverse transcription-polymerase chain reaction （RT-PCR）. The apoptosis, proliferation and invasive ability of lung cancer cells before and after transfection were examined with flow cytometry, MTT and transwell methods. Results After transfection of axin gene into BE1 cells （BE1-axin cells）, axin mRNA and protein were overexpressed significantly. Meauwhile, the protein expression of β-catenin and mRNA expression of TCF-4 were decreased significantly in BEl-axin cells than that in BE1 or vector control cells. The flow cytometry revealed that the apoptosis rate of BEl-axin cells was enhanced, but MTT and Transwell assay indicated that the proliferation and invasive ability were decreased significantly in BE1-axin cells than those in BE 1 or vector control cells. Conclusion The overexpression of axin could down-regulate the protein expression of β-catenin and the transcription of TCF-4, and inhibit the proliferation and invasive ability of lung cancer cells.