Hou Liejun, Li Qiang, Yu Yiming, Li Ming, Zhang Dayong
Department of Urology, The Affiliated Hospital of Medical College, Ningbo University, Ningbo, Zhejiang 315021, P.R. China.
Department of Urology, The First Affiliated Hospital of Shihezi University School of Medicine, Shihezi, Xinjiang 832000, P.R. China.
Mol Med Rep. 2016 Feb;13(2):1681-8. doi: 10.3892/mmr.2015.4733. Epub 2015 Dec 30.
Mounting evidence suggested that histone H4K20-specific methyltransferase SET8 is required to maintain the malignant phenotype of various cancer types; however, the role of SET8 in mediating tumor metastasis in prostate cancer (PCa) has remained elusive. The present study demonstrated that small interfering RNA-mediated knockdown of SET8 inhibited the invasive potential of the PCa cell line PC-3 in vitro. Knockdown of SET8 reduced sphere formation, downregulated E-cadherin and α-catenin, and upregulated N-cadherin and vimentin expression in CaP cells, while upregulation of SET8 expression with a recombinant plasmid had the opposite effect. Furthermore, SET8 was shown to be physically associated with the epithelial-mesenchymal transition (EMT) inducer zinc finger E-box-binding homeobox 1 (ZEB1) in PCa cell lines. Chromatin immunoprecipitation suggested that SET8 binds to the promoter of cell adhesion molecule E-cadherin and vimentin. Luciferase reporter assays suggested that E-cadherin and vimentin are direct targets of SET8; furthermore, loss- and gain-of function studies of SET8 and ZEB1 indicated that suppression of downstream E-cadherin and activation of vimentin are important mechanisms by which SET8 and ZEB1 cooperatively trigger metastasis. Furthermore, SET8-induced methylated H4K20 was indicated to exert a dual function in ZEB1-regulated gene expression. In conclusion, the present study revealed that SET8 and ZEB1 are functionally interdependent in promoting the EMT and enhancing the invasive potential of PCa cells in vitro.
越来越多的证据表明，组蛋白H4K20特异性甲基转移酶SET8是维持多种癌症类型恶性表型所必需的；然而，SET8在介导前列腺癌（PCa）肿瘤转移中的作用仍不清楚。本研究表明，小干扰RNA介导的SET8敲低在体外抑制了PCa细胞系PC-3的侵袭潜能。SET8敲低减少了CaP细胞中的球体形成，下调了E-钙黏蛋白和α-连环蛋白，并上调了N-钙黏蛋白和波形蛋白的表达，而用重组质粒上调SET8表达则产生相反的效果。此外，在PCa细胞系中，SET8被证明与上皮-间质转化（EMT）诱导因子锌指E盒结合同源框1（ZEB1）存在物理关联。染色质免疫沉淀表明，SET8与细胞黏附分子E-钙黏蛋白和波形蛋白的启动子结合。荧光素酶报告基因检测表明，E-钙黏蛋白和波形蛋白是SET8的直接靶点；此外，SET8和ZEB1的功能缺失和功能获得研究表明，下游E-钙黏蛋白的抑制和波形蛋白的激活是SET8和ZEB1协同触发转移的重要机制。此外，SET8诱导的H4K20甲基化在ZEB1调节的基因表达中发挥双重作用。总之，本研究揭示了SET8和ZEB1在促进EMT和增强PCa细胞体外侵袭潜能方面在功能上相互依赖。
