Song Guisheng, Zhang Yuxia, Wang Li
Department of Medicine, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah 84132, USA.
J Biol Chem. 2009 Nov 13;284(46):31921-7. doi: 10.1074/jbc.M109.046862. Epub 2009 Sep 1.
MicroRNAs contribute to cancer development by acting as oncogenes or tumor suppressor genes. However, only a few microRNA target genes were determined. We identified a nearly perfect complementarity between miR-206 and the 3'-untranslated regions of both mouse and human notch3. Expression of miR-206 decreased the luciferase activity dose-dependently when cotransfected with the mouse or human notch3 3'-untranslated region-luciferase reporter containing the miR-206 target site in HeLa cells. This suppression was relieved by deletion and mutation of the miR-206-binding site and was partially recovered by expression of notch3 or by a specific inhibitor of miR-206. Interestingly, overexpression of miR-206 decreased the levels of both Notch3 protein and mRNA. Expression of miR-206 markedly induced apoptotic cell death and blocked the anti-apoptotic activity of Notch3. In addition, ectopic expression of miR-206 inhibited HeLa cell migration and focus formation. Therefore, we identified miR-206 as a pro-apoptotic activator of cell death, which was associated with its inhibition of notch3 signaling and tumor formation. The inhibition of cancer cell migration and focus formation by miR-206 strongly suggests that miR-206 may function as a novel tumor suppressor.
微小RNA通过充当癌基因或肿瘤抑制基因来促进癌症发展。然而，仅确定了少数微小RNA靶基因。我们发现miR-206与小鼠和人类Notch3的3'-非翻译区存在近乎完美的互补性。当在HeLa细胞中与含有miR-206靶位点的小鼠或人类Notch3 3'-非翻译区荧光素酶报告基因共转染时，miR-206的表达剂量依赖性地降低了荧光素酶活性。miR-206结合位点的缺失和突变可解除这种抑制作用，Notch3的表达或miR-206的特异性抑制剂可部分恢复这种抑制作用。有趣的是，miR-206的过表达降低了Notch3蛋白和mRNA的水平。miR-206的表达显著诱导凋亡性细胞死亡并阻断Notch3的抗凋亡活性。此外，miR-206的异位表达抑制了HeLa细胞的迁移和集落形成。因此，我们确定miR-206是细胞死亡的促凋亡激活剂，这与其对Notch3信号传导和肿瘤形成的抑制作用有关。miR-206对癌细胞迁移和集落形成的抑制强烈表明miR-206可能作为一种新型肿瘤抑制因子发挥作用。
