Medical Genomics Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 305-806, Republic of Korea.
Carcinogenesis. 2014 May;35(5):1020-7. doi: 10.1093/carcin/bgt409. Epub 2013 Dec 9.
Tumorigenesis is a consequence of failures of multistep defense mechanisms against deleterious perturbations that occur at the genomic, epigenomic, transcriptomic and proteomic levels. To uncover previously unrecognized genes that undergo multilevel perturbations in gastric cancer (GC), we integrated epigenomic and transcriptomic approaches using two recently developed tools: MENT and GENT. This integrative analysis revealed that nine Hippo pathway-related genes, including components [FAT, JUB, LATS2, TEA domain family member 4 (TEAD4) and Yes-associated protein 1 (YAP1)] and targets (CRIM1, CYR61, CTGF and ITGB2), are concurrently hypomethylated at promoter CpG sites and overexpressed in GC tissues. In particular, TEAD4, a link between Hippo pathway components and targets, was significantly hypomethylated at CpG site cg21637033 (P = 3.8 × 10(-) (20)) and overexpressed (P = 5.2 × 10(-) (10)) in 108 Korean GC tissues compared with the normal counterparts. A reduced level of methylation at the TEAD4 promoter was significantly associated with poor outcomes, including large tumor size, high-grade tumors and low survival rates. Compared with normal tissues, the TEAD4 protein was more frequently found in the nuclei of tumor cells along with YAP1 in 53 GC patients, demonstrating the posttranslational activation of this protein. Moreover, the knockdown of TEAD4 resulted in the reduced growth of GC cells both in vitro and in vivo. Finally, chromatin immunoprecipitation-sequencing and microarray analysis revealed the oncogenic properties of TEAD4 and its novel targets (ADM, ANG, ARID5B, CALD1, EDN2, FSCN1 and OSR2), which are involved in cell proliferation and migration. In conclusion, the multilevel perturbations of TEAD4 at epigenetic, transcriptional and posttranslational levels may contribute to GC development.
肿瘤发生是基因组、表观基因组、转录组和蛋白质组水平上发生有害扰动时多步防御机制失效的结果。为了揭示胃癌（GC）中经历多层次扰动的先前未被识别的基因，我们使用两种新开发的工具：MENT 和 GENT，整合了表观基因组和转录组方法。这种综合分析表明，Hippo 通路相关的 9 个基因（包括 FAT、JUB、LATS2、TEA 结构域家族成员 4（TEAD4）和 Yes 相关蛋白 1（YAP1））和靶基因（CRIM1、CYR61、CTGF 和 ITGB2）在 GC 组织中同时启动子 CpG 位点低甲基化和过表达。特别是，Hippo 通路成分和靶基因之间的连接物 TEAD4 在 CpG 位点 cg21637033 处显著低甲基化（P = 3.8×10(-)(20)），在 108 个韩国 GC 组织中过表达（P = 5.2×10(-)(10)）与正常组织相比。TEAD4 启动子低甲基化水平与不良结局显著相关，包括大肿瘤大小、高级别肿瘤和低生存率。与正常组织相比，在 53 名 GC 患者中，TEAD4 蛋白更频繁地与 YAP1 一起出现在肿瘤细胞核中，表明该蛋白的翻译后激活。此外，TEAD4 的敲低导致 GC 细胞在体外和体内的生长减少。最后，染色质免疫沉淀测序和微阵列分析揭示了 TEAD4 及其新靶基因（ADM、ANG、ARID5B、CALD1、EDN2、FSCN1 和 OSR2）的致癌特性，这些基因参与细胞增殖和迁移。总之，TEAD4 在表观遗传、转录和翻译后水平的多层次扰动可能有助于 GC 的发展。
