Department of Laboratory Medicine, Peking University Third Hospital, Peking University Health Science Center, Beijing, 100191, China.
Cell Death Dis. 2020 Feb 26;11(2):151. doi: 10.1038/s41419-020-2350-2.
Although the deregulation of lysine methyltransferase (su(var)-3-9, enhancer-of-zeste, trithorax) domain-containing protein 7/9 (SET7/9) has been identified in a variety of cancers, the potential role of SET7/9 and the molecular events in which it is involved in breast cancer remain obscure. Using the online Human Protein Atlas and GEO databases, the expression of SET7/9 was analyzed. Furthermore, we investigated the underlying mechanisms using chromatin immunoprecipitation-based deep sequencing (ChIP-seq) and quantitative ChIP assays. To explore the physiological role of SET7/9, functional analyses such as CCK-8, colony formation, and transwell assays were performed and a xenograft tumor model was generated with the human breast cancer cell lines MCF-7 and MDA-MB-231. Mass spectrometry, co-immunoprecipitation, GST pull-down, and ubiquitination assays were used to explore the mechanisms of SET7/9 function in breast cancer. We evaluated the expression of SET7/9 in different breast cancer cohorts and found that higher expression indicated worse survival times in these public databases. We demonstrated positive effects of SET7/9 on cell proliferation, migration, and invasion via the activation of Runt-related transcription factor 2 (RUNX2). We demonstrate that tripartite motif-containing protein 21 (TRIM21) physically associates with SET7/9 and functions as a major negative regulator upstream of SET7/9 through a proteasome-dependent mechanism and increased ubiquitination. Taken together, our data suggest that SET7/9 has a promoting role via the regulation of RUNX2, whereas TRIM21-mediated SET7/9 degradation acts as an anti-braking system in the progression of breast cancer.
尽管赖氨酸甲基转移酶（su(var)-3-9、增强子-of-zeste、trithorax）结构域包含蛋白 7/9（SET7/9）的去调控已在多种癌症中被鉴定出来，但 SET7/9 的潜在作用及其参与乳腺癌的分子事件仍然不清楚。使用在线人类蛋白质图谱和 GEO 数据库分析了 SET7/9 的表达。此外，我们还使用染色质免疫沉淀测序（ChIP-seq）和定量 ChIP 检测研究了潜在机制。为了探索 SET7/9 的生理作用，进行了 CCK-8、集落形成和 Transwell 检测等功能分析，并使用 MCF-7 和 MDA-MB-231 人乳腺癌细胞系生成了异种移植肿瘤模型。质谱分析、共免疫沉淀、GST 下拉和泛素化检测用于探索 SET7/9 在乳腺癌中的功能机制。我们评估了不同乳腺癌队列中 SET7/9 的表达，发现这些公共数据库中更高的表达表明生存时间更差。我们通过激活 Runt 相关转录因子 2（RUNX2）证明了 SET7/9 对细胞增殖、迁移和侵袭的积极影响。我们证明三肽基含 21 蛋白（TRIM21）通过蛋白酶体依赖的机制和增加的泛素化与 SET7/9 物理结合，并作为 SET7/9 的主要负调控因子发挥作用。总之，我们的数据表明，SET7/9 通过调节 RUNX2 发挥促进作用，而 TRIM21 介导的 SET7/9 降解在乳腺癌的进展中充当制动系统。
