BK21 Plus, Department of Cogno-Mechatronics Engineering, Pusan National University, Busan, 46241, Republic of Korea.
Department of Biosciences, Dong-A University, Busan, 49315, Republic of Korea.
Biochem Biophys Res Commun. 2019 Mar 26;511(1):122-128. doi: 10.1016/j.bbrc.2019.02.036. Epub 2019 Feb 14.
Although our previous studies have showed that a novel oncogene, cancer upregulated gene (CUG)2 induced epithelial-mesenchymal transition (EMT), the detailed molecular mechanism remains unknown. Because several lines of evidence documented that Yes-Associated Protein (YAP)1 is closely associated with cancer stem cell (CSC)-like phenotypes including EMT, stemness, and drug resistance, we wondered if YAP1 is involved in CUG2-induced EMT. We herein found that the overexpression of CUG2 increased YAP1 expression at the transcriptional as well as protein levels. Chromatin immunoprecipitation assay revealed that the elevated YAP1 transcripts are attributed to c-Jun and AP2 bindings to the YAP1 promoter. Akt and MAPK kinases including ERK, JNK, and p38 MAPK enhanced the level of YAP1 protein. In spite of a close relationship between β-catenin and YAP1, not β-catenin but NEK2 played the role in increasing YAP1 expression. Silencing YAP1 inhibited CUG2-induced cell migration and invasion. N-cadherin and vimentin expressions were decreased during YAP1 knockdown. The suppression of YAP1 diminished TGF-β transcriptional activity and expression as well as phosphorylation level of Smad2 and Twist protein. Conversely, LY2109761 or Smad2 siRNA treatment reduced YAP1 protein levels, indicating a close interplay between YAP1 and TGF-β signaling. Taken together, we suggest that CUG2 induces up-regulation of YAP1 expression, leading to enhancing CUG2-induced EMT via a close crosstalk between YAP1 and TGF-β signaling.
虽然我们之前的研究表明，一种新的癌基因——癌上调基因（CUG）2 诱导上皮-间充质转化（EMT），但其详细的分子机制尚不清楚。有几条证据表明 Yes 相关蛋白（YAP）1 与癌症干细胞（CSC）样表型密切相关，包括 EMT、干性和耐药性，因此我们想知道 YAP1 是否参与 CUG2 诱导的 EMT。我们在此发现，CUG2 的过表达在转录和蛋白水平上均增加了 YAP1 的表达。染色质免疫沉淀分析显示，升高的 YAP1 转录本归因于 c-Jun 和 AP2 与 YAP1 启动子的结合。Akt 和 MAPK 激酶，包括 ERK、JNK 和 p38 MAPK，增强了 YAP1 蛋白的水平。尽管 β-catenin 和 YAP1 之间存在密切关系，但增加 YAP1 表达的不是 β-catenin，而是 NEK2。沉默 YAP1 抑制了 CUG2 诱导的细胞迁移和侵袭。在 YAP1 敲低期间，N-钙粘蛋白和波形蛋白的表达减少。YAP1 的抑制降低了 TGF-β 的转录活性和表达以及 Smad2 和 Twist 蛋白的磷酸化水平。相反，LY2109761 或 Smad2 siRNA 处理降低了 YAP1 蛋白水平，表明 YAP1 和 TGF-β 信号之间存在密切的相互作用。总之，我们认为 CUG2 诱导 YAP1 表达上调，通过 YAP1 和 TGF-β 信号之间的密切串扰，增强 CUG2 诱导的 EMT。
