Chua H L, Bhat-Nakshatri P, Clare S E, Morimiya A, Badve S, Nakshatri H
Department of Surgery, Indiana University School of Medicine, Indianapolis, IN, USA.
Oncogene. 2007 Feb 1;26(5):711-24. doi: 10.1038/sj.onc.1209808. Epub 2006 Jul 24.
The transcription factor nuclear factor kappa B (NF-kappaB) is constitutively active in both cancer cells and stromal cells of breast cancer; however, the precise role of activated NF-kappaB in cancer progression is not known. Using parental MCF10A cells and a variant that expresses the myoepithelial marker p63 stably overexpressing the constitutively active p65 subunit of NF-kappaB (MCF10A/p65), we show that NF-kappaB suppresses the expression of epithelial specific genes E-cadherin and desmoplakin and induces the expression of the mesenchymal specific gene vimentin. P65 also suppressed the expression of p63 and the putative breast epithelial progenitor marker cytokeratin 5/6. MCF10A/p65 cells were phenotypically similar to cells undergoing epithelial to mesenchymal transition (EMT). MCF10A/p65 cells failed to form characteristic acini in three-dimensional Matrigel. Analysis of parental and MCF10A/p65 cells for genes previously shown to be involved in EMT revealed elevated expression of ZEB-1 and ZEB-2 in MCF10A/p65 cells compared to parental cells. In transient transfection assays, p65 increased ZEB-1 promoter activity. Furthermore, MCF10A cells overexpressing ZEB-1 showed reduced E-cadherin and p63 expression and displayed an EMT phenotype. The siRNA against ZEB-1 or ZEB-2 reduced the number of viable MCF10A/p65 but not parental cells, suggesting the dependence of MCF10A/p65 cells to ZEB-1 and ZEB-2 for cell cycle progression or survival. MCF10A cells chronically exposed to tumor necrosis factor alpha (TNFalpha), a potent NF-kappaB inducer, also exhibited the EMT-like phenotype and ZEB-1/ZEB-2 induction, both of which were reversed following TNFalpha withdrawal.
转录因子核因子κB（NF-κB）在乳腺癌的癌细胞和基质细胞中均呈组成性激活状态；然而，激活的NF-κB在癌症进展中的确切作用尚不清楚。我们使用亲本MCF10A细胞和一个稳定过表达NF-κB组成性激活的p65亚基（MCF10A/p65）并表达肌上皮标志物p63的变体，发现NF-κB抑制上皮特异性基因E-钙黏蛋白和桥粒斑蛋白的表达，并诱导间充质特异性基因波形蛋白的表达。P65还抑制p63以及假定的乳腺上皮祖细胞标志物细胞角蛋白5/6的表达。MCF10A/p65细胞在表型上类似于经历上皮-间充质转化（EMT）的细胞。MCF10A/p65细胞在三维基质胶中无法形成特征性腺泡。对亲本细胞和MCF10A/p65细胞中先前已证明参与EMT的基因进行分析，结果显示与亲本细胞相比，MCF10A/p65细胞中ZEB-1和ZEB-2的表达升高。在瞬时转染实验中，p65增加了ZEB-1启动子活性。此外，过表达ZEB-1的MCF10A细胞显示E-钙黏蛋白和p63表达降低，并呈现出EMT表型。针对ZEB-1或ZEB-2的小干扰RNA（siRNA）减少了存活的MCF10A/p65细胞数量，但未减少亲本细胞数量，这表明MCF10A/p65细胞在细胞周期进程或存活方面对ZEB-1和ZEB-2存在依赖性。长期暴露于肿瘤坏死因子α（TNFα，一种强效的NF-κB诱导剂）的MCF10A细胞也表现出EMT样表型以及ZEB-1/ZEB-2的诱导，在撤除TNFα后这两者均逆转。
