Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory for Biocontrol, Sun Yat-Sen University, Guangzhou, PR China.
Oncogene. 2012 Jun 14;31(24):2968-78. doi: 10.1038/onc.2011.461. Epub 2011 Oct 24.
The microRNA-371-373 (miR-371-373) cluster is specifically expressed in human embryonic stem cells (ESCs) and is thought to be involved in stem cell maintenance. Recently, microRNAs (miRNAs) of this cluster were shown to be frequently upregulated in several human tumors. However, the regulatory mechanism for the involvement of the miR-371-373 cluster in human ESCs or cancer cells remains unclear. In this study, we explored the relationship between this miRNA cluster and the Wnt/β-catenin-signaling pathway, which has been shown to be involved in both stem cell maintenance and tumorigenesis. We show that miR-371-373 expression is induced by lithium chloride and is positively correlated with Wnt/β-catenin-signaling activity in several human cancer cell lines. Mechanistically, three TCF/LEF1-binding elements (TBEs) were identified in the promoter region and shown to be required for Wnt-dependent activation of miR-371-373. Interestingly, we also found that miR-372&373, in turn, activate Wnt/β-catenin signaling. In addition, four protein genes related to the Wnt/β-catenin-signaling pathway were identified as direct targets of miR-372&373, including Dickkopf-1 (DKK1), a well-known inhibitor of Wnt/β-catenin signaling. Using a lentiviral system, we showed that overexpression of miR-372 or miR-373 promotes cell growth and the invasive activity of tumor cells as knockdown of DKK1. Taken together, our study demonstrates a novel β-catenin/LEF1-miR-372&373-DKK1 regulatory feedback loop, which may have a critical role in regulating the activity of Wnt/β-catenin signaling in human cancer cells.
miR-371-373（miR-371-373）簇在人胚胎干细胞（ESCs）中特异性表达，被认为参与干细胞维持。最近，该簇的 microRNAs（miRNAs）在几种人类肿瘤中频繁上调。然而，miR-371-373 簇参与人 ESC 或癌细胞的调节机制尚不清楚。在这项研究中，我们探讨了该 miRNA 簇与 Wnt/β-catenin 信号通路之间的关系，该通路已被证明参与干细胞维持和肿瘤发生。我们表明，miR-371-373 的表达由氯化锂诱导，并与几种人类癌细胞系中的 Wnt/β-catenin 信号活性呈正相关。从机制上讲，在启动子区域鉴定出三个 TCF/LEF1 结合元件（TBE），并显示它们是 Wnt 依赖性 miR-371-373 激活所必需的。有趣的是，我们还发现 miR-372&373 反过来激活 Wnt/β-catenin 信号。此外，还鉴定出与 Wnt/β-catenin 信号通路相关的四个蛋白基因是 miR-372&373 的直接靶标，包括 Dickkopf-1（DKK1），这是 Wnt/β-catenin 信号的一种众所周知的抑制剂。使用慢病毒系统，我们表明 miR-372 或 miR-373 的过表达促进细胞生长和肿瘤细胞的侵袭活性，如 DKK1 的敲低。总之，我们的研究表明了一种新的β-catenin/LEF1-miR-372&373-DKK1 调节反馈回路，它可能在调节人癌细胞中 Wnt/β-catenin 信号的活性中起着关键作用。
