Wang Junxiang, Sun Chengfa, Li Jian, Jiang Hua, Qiu Yun, Gong Mingjie
Department of Neurosurgery, Changshu No. 2 People's Hospital, The Affiliated Changshu Hospital of Xuzhou Medical University, Changshu, Suzhou, Jiangsu 215500, P.R. China.
Oncol Lett. 2022 Feb;23(2):41. doi: 10.3892/ol.2021.13159. Epub 2021 Dec 6.
ETS variant transcription factor 4 (ETV4) is a common cancer-promoting transcription factor and its expression has been found to be significantly upregulated in glioblastoma multiforme (GBM), as determined via analysis of the Gene Expression Profiling Interactive Analysis (GEPIA) database. In addition, our previous study demonstrated that ETV4 expression was highly positively correlated with epithelial membrane protein 1 (EMP1). The present study aimed to determine whether ETV4 could influence the activation of the PI3K/AKT/mTOR signaling pathway to affect the autophagy and apoptosis of GBM cells by regulating the transcriptional activity of EMP1. In addition to the analysis of the GEPIA database, the expression levels of ETV4 were also investigated in several different GBM cell lines. After interfering with the expression of ETV4, western blotting was used to detect the expression levels of autophagy- and apoptosis-related proteins, and a TUNEL assay was used to detect the levels of cell apoptosis. Dual luciferase reporter and chromatin immunoprecipitation assays were used to verify the potential binding site of ETV4 on EMP1. Western blotting was also used to analyze the expression levels of PI3K/AKT/mTOR signaling pathway-related proteins. The results of the current study revealed that the expression levels of ETV4 were significantly upregulated in GBM cell lines compared with those in normal glial cells. In the GBM cell line, LN-229, ETV4 was discovered to bind to the EMP1 promoter and positively regulate the expression of EMP1. The knockdown of ETV4 expression inhibited the PI3K/AKT/mTOR signaling pathway activity to promote autophagy and apoptosis, and this effect could be partially reversed by overexpressing EMP1. In conclusion, these findings indicated that the knockdown of ETV4 in GBM cells may reduce the transcriptional activation of EMP1 and thereby inhibit PI3K/AKT/mTOR signaling pathway activity to promote autophagy and apoptosis. This provides a novel insight into potential strategies for the treatment of GBM via the induction of autophagy-dependent apoptosis.
ETS变异转录因子4（ETV4）是一种常见的促癌转录因子，通过基因表达谱交互分析（GEPIA）数据库分析发现，其在多形性胶质母细胞瘤（GBM）中的表达显著上调。此外，我们之前的研究表明，ETV4表达与上皮膜蛋白1（EMP1）高度正相关。本研究旨在确定ETV4是否可通过调节EMP1的转录活性影响PI3K/AKT/mTOR信号通路的激活，从而影响GBM细胞的自噬和凋亡。除了分析GEPIA数据库外，还在几种不同的GBM细胞系中研究了ETV4的表达水平。干扰ETV4表达后，采用蛋白质免疫印迹法检测自噬和凋亡相关蛋白的表达水平，采用TUNEL法检测细胞凋亡水平。采用双荧光素酶报告基因和染色质免疫沉淀试验验证ETV4在EMP1上的潜在结合位点。蛋白质免疫印迹法还用于分析PI3K/AKT/mTOR信号通路相关蛋白的表达水平。本研究结果显示，与正常神经胶质细胞相比，GBM细胞系中ETV4的表达水平显著上调。在GBM细胞系LN-229中，发现ETV4与EMP1启动子结合并正向调节EMP1的表达。敲低ETV4表达可抑制PI3K/AKT/mTOR信号通路活性，促进自噬和凋亡，而过表达EMP1可部分逆转这种作用。总之，这些发现表明，敲低GBM细胞中的ETV4可能会降低EMP1的转录激活，从而抑制PI3K/AKT/mTOR信号通路活性，促进自噬和凋亡。这为通过诱导自噬依赖性凋亡治疗GBM的潜在策略提供了新的见解。
