Paccione Rachel J, Miyazaki Hiroshi, Patel Vyomesh, Waseem Ahmad, Gutkind J Silvio, Zehner Zendra E, Yeudall W Andrew
Philips Institute, Virginia Commonwealth University, Richmond, Virginia, USA.
Mol Cancer Ther. 2008 Sep;7(9):2894-903. doi: 10.1158/1535-7163.MCT-08-0450.
At later stages of tumor progression, epithelial carcinogenesis is associated with transition to a mesenchymal phenotype, which may contribute to the more aggressive properties of cancer cells and may be stimulated by growth factors such as epidermal growth factor and transforming growth factor-beta. Previously, we found that cells derived from a nodal metastatic squamous cell carcinoma are highly proliferative and motile in vitro and tumorigenic in vivo. In the current study, we have investigated the role of vimentin in proliferation and motility. Cells derived from nodal metastasis express high levels of vimentin, which is undetectable in tumor cells derived from a synchronous primary lesion of tongue. Vimentin expression was enhanced by epidermal growth factor and transforming growth factor-beta both independently and in combination. Use of RNA interference resulted in the generation of stable cell lines that express constitutively low levels of vimentin. RNA interference-mediated vimentin knockdown reduced cellular proliferation, migration, and invasion through a basement membrane substitute by 3-fold compared with nontargeting controls. In addition, cells with reduced vimentin reexpressed differentiation-specific keratins K13, K14, and K15 as a result of increased gene transcription as judged by quantitative PCR and promoter-reporter assays. Furthermore, cells in which vimentin expression was reduced showed a greatly decreased tumorigenic potential, as tumors developing from these cells were 70% smaller than those from control cells. The data suggest that reversal of the mesenchymal phenotype by inhibiting vimentin expression results in reexpression of epithelial characteristics and reduced tumor aggressiveness.
在肿瘤进展的后期阶段，上皮细胞癌变与向间充质表型的转变相关，这可能导致癌细胞具有更强的侵袭性，并且可能受到表皮生长因子和转化生长因子-β等生长因子的刺激。此前，我们发现源自淋巴结转移鳞状细胞癌的细胞在体外具有高度增殖性和运动性，在体内具有致瘤性。在本研究中，我们研究了波形蛋白在增殖和运动中的作用。源自淋巴结转移的细胞表达高水平的波形蛋白，而在源自舌同步原发性病变的肿瘤细胞中则检测不到。表皮生长因子和转化生长因子-β单独或联合使用均可增强波形蛋白的表达。使用RNA干扰产生了稳定表达低水平波形蛋白的细胞系。与非靶向对照相比，RNA干扰介导的波形蛋白敲低使细胞增殖、迁移以及穿过基底膜替代物的侵袭减少了3倍。此外，波形蛋白减少的细胞由于基因转录增加，重新表达了分化特异性角蛋白K13、K14和K15，这通过定量PCR和启动子报告基因分析得以判断。此外，波形蛋白表达降低的细胞显示出致瘤潜力大大降低，因为由这些细胞形成的肿瘤比对照细胞形成的肿瘤小70%。数据表明，通过抑制波形蛋白表达来逆转间充质表型会导致上皮特征的重新表达并降低肿瘤侵袭性。
