Department of Infectious Diseases, Tangdu Hospital, Air Force Medical University, Xi'an, 710038, China.
Clin Transl Oncol. 2022 Oct;24(10):1998-2009. doi: 10.1007/s12094-022-02859-y. Epub 2022 Jun 29.
The Wnt/β-catenin signaling pathway is frequently activated in hepatocellular carcinoma (HCC). A number of studies have focused on the aberrant hypermethylation of the DKK family proteins and its role in regulating the activation of specific signaling pathways. However, the exact way by which DKK regulates the signaling pathway caused by Core protein of HCV has not been reported. In the present study, we evaluated the expression level of DKK and its aberrant promoter methylation to investigate the involvement of epigenetic regulation in hepatoma cell lines. The transcription and protein expression of DKK1 was significantly increased, whereas the transcription and protein expression levels of DKK2, DKK3, and DKK4 were significantly decreased following overexpression of Core protein. Pyrosequencing indicated that hypermethylation of DKK3 was increased. This was associated with increased expression of Dnmt1. The investigation of the molecular mechanism indicated that HCV Core protein interacted with Dnmt1, which combined with the promoter of DKK3, leading to methylation of DKK3. Functional studies indicated that Core protein promoted the growth, migration and invasion of cancer cells. However, upregulation of the expression of DKK3 and/or the knockdown of the expression of Dnmt1 inhibited the growth, migration and invasion of cancer cells. Taken together, the data indicated that epigenetic silencing of DKK3 caused by Dnmt1 activated the Wnt/β-catenin pathway in HCV Core-mediated HCC. Therefore, DKK3 may be a potential diagnostic and therapeutic target for HCC.
Wnt/β-连环蛋白信号通路在肝细胞癌（HCC）中经常被激活。许多研究集中在 DKK 家族蛋白的异常高甲基化及其在调节特定信号通路激活中的作用。然而，DKK 调节 HCV 核心蛋白引起的信号通路的确切方式尚未报道。在本研究中，我们评估了 DKK 的表达水平及其异常启动子甲基化，以研究表观遗传调控在肝癌细胞系中的参与。在 HCV 核心蛋白过表达后，DKK1 的转录和蛋白表达显著增加，而 DKK2、DKK3 和 DKK4 的转录和蛋白表达水平显著降低。焦磷酸测序表明 DKK3 的高甲基化增加。这与 Dnmt1 的表达增加有关。分子机制的研究表明，HCV 核心蛋白与 Dnmt1 相互作用，与 DKK3 的启动子结合，导致 DKK3 的甲基化。功能研究表明，核心蛋白促进癌细胞的生长、迁移和侵袭。然而，上调 DKK3 的表达和/或下调 Dnmt1 的表达抑制了癌细胞的生长、迁移和侵袭。总之，数据表明，由 Dnmt1 引起的 DKK3 的表观遗传沉默激活了 HCV 核心介导的 HCC 中的 Wnt/β-连环蛋白通路。因此，DKK3 可能是 HCC 的潜在诊断和治疗靶点。
