Dkk3, downregulated in cervical cancer, functions as a negative regulator of β-catenin
Dkk3, downregulated in cervical cancer, functions as a negative regulator of β-catenin
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DOI：
10.1002/ijc.23913
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发表时间：
2009-01-15
影响因子：
6.4
通讯作者：
Lee, Je-Ho
中科院分区：
文献类型：
--
作者：
Lee, Eun-Ju;Jo, Minwha;Lee, Je-Ho
Wnt/β-连环蛋白信号通路在源自人子宫颈的角质形成细胞的恶性转化期间被激活。Dkk 1、2和4已显示调节Wnt诱导的β-连环蛋白信号通路的稳定。然而，Dkk 3在该途径中的功能尚不清楚。通过cDNA微阵列和随后的实时荧光PCR比较宫颈癌和正常宫颈组织中Dkk 3基因的表达谱，发现Dkk 3基因在宫颈癌中经常下调。甲基化研究显示，宫颈癌细胞系和70例宫颈癌组织标本中有22例（31.4%）Dkk 3启动子甲基化。在配对的正常和肿瘤组织样本中，rhis启动子甲基化与Dkk 3 mRNA表达降低相关。此外，将Dkk 3重新引入HeLa宫颈癌细胞导致集落形成减少和细胞生长延迟。Dkk 3的强制表达以剂量依赖性方式显著减弱了β-连环蛋白响应性荧光素酶活性，并降低了β-连环蛋白水平。通过利用酵母双杂交筛选，β-连环蛋白的负调节因子β TrCP被鉴定为新的Dkk 3相互作用伴侣。与β TrCP共表达协同增强Dkk 3对β-连环蛋白的抑制功能。Dkk 3的稳定表达阻断了0-连环蛋白的不清楚的易位，导致其下游靶点（VEGF和细胞周期蛋白D）的下调，而Dkk 3的敲低消除了这种阻断。我们从我们的发现中得出结论，Dkk 3是β-连环蛋白的负调节因子，其下调有助于β-连环蛋白信号通路的激活。(C)2008 Wiley-Liss，Inc.
The Wnt/beta-catenin signaling pathway is activated during the malignant transformation of keratinocytes that originate from the human uterine cervix. Dkk1, 2 and 4 have been shown to modulate the Wnt-induced stabilization of the beta-catenin signaling pathway. However, the function of Dkk3 in this pathway is unknown. Comparison of the Dkk3 gene expression profiles in cervical cancer and normal cervical tissue by cDNA microarray and subsequent real-time PCR revealed that the Dkk3 gene is frequently down-regulated in the cancer. Methylation studies showed that the promoter of Dkk3 was methylated in cervical cancer cell lines and 22 (31.4%) of 70 cervical cancer tissue specimens. rhis promoter methylation was associated with reduced expression or Dkk3 mRNA in the paired normal and tumor tissue samples. Further, the reintroduction or Dkk3 into HeLa cervical cancer cells resulted in reduced colony formation and retarded cell growth. The forced expression of Dkk3 markedly attenuated P-catenin-responsive luciferase activity in a dose-dependent manner and decreased the beta-catenin levels. By utilizing a yeast two-hybrid screen, beta TrCP, a negative regulator of beta-catenin was identified as a novel Dkk3-interacting partner. Coexpression with beta TrCP synergistically enhanced the inhibitory function of Dkk3 on beta-catenin. The stable expression of Dkk3 blocks the unclear translocation of 0-catenin, resulting in downregulation of its downstream targets (VEGF and cylcin D), whereas knockdown of Dkk3 abrogates this blocking. We conclude from our finding that Dkk3 is a negative regulator or beta-catenin and its downregulation contribute to an activation of the beta-catenin signaling pathway. (C) 2008 Wiley-Liss, Inc.