GTSE1 promotes SNAIL1 degradation by facilitating its nuclear export in hepatocellular carcin oma cells
GTSE1 promotes SNAIL1 degradation by facilitating its nuclear export in hepatocellular carcin oma cells
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GTSE1 通过促进肝细胞癌细胞的核输出来促进 SNAIL1 降解
DOI：
10.3892/mmr.2021.12093
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发表时间：
2021-06-01
影响因子：
3.4
通讯作者：
Lian, Yi-Fan
中科院分区：
文献类型：
--
作者：
Li, Shan-Shan;Chen, Dong-Mei;Lian, Yi-Fan
Snail 家族转录阻遏蛋白 1 (SNAIL1) 是上皮间质转化 (EMT) 过程的主要诱导剂，有助于肿瘤转移和复发。我们之前的研究报道，G(2) 和 S 期表达 1 (GTSE1) 在调节肝细胞癌 (HCC) 中 SNAIL1 的表达中发挥作用。然而，其根本机制仍不清楚。因此，本研究旨在通过在 HCC 细胞模型中进行的体外测定来揭示 GTSE1 对 SNAIL1 表达的调节机制。结果表明，GTSE1 过表达或小干扰 RNA 介导的敲低分别下调和上调内源 SNAIL1 表达。通过放线菌酮追踪实验，发现 GTSE1 过表达增加了 SNAIL1 的蛋白质周转，而 GTSE1 的敲低则降低了其降解率。此外，使用免疫荧光和亚细胞分级分离方法证明 GTSE1 过表达诱导 SNAIL1 的细胞质表达。核输出抑制剂 leptomycin B 能够减少由 GTSE1 过表达引起的 SNAIL1 的细胞质滞留。此外，TGF-β I处理增加了GTSE1的mRNA和蛋白表达水平，并降低了SNAIL1的蛋白表达水平，但不影响其在Huh7细胞中的mRNA转录。研究还发现，TGF-β 信号传导可以通过反式激活 GTSE1 启动子中的 Smad 结合元件来上调 GTSE1 表达的转录。此外，Huh7 细胞中 TGF-β I 诱导的 SNAIL1 蛋白表达降低是 GTSE1 依赖性的。总之，目前的研究提供了一种新机制，GTSE1 通过调节 SNAIL1 在 HCC 细胞中的亚细胞定位来影响 SNAIL1 的稳定性。
Snail family transcriptional repressor 1 (SNAIL1) is a master inducer of the epithelial-to-mesenchymal transition (EMT) process, contributing to tumor metastasis and recurrence. Our previous study reported that G(2) and S phase-expressed-1 (GTSE1) served a role in regulating SNAIL1 expression in hepatocellular carcinoma (HCC). However, the underlying mechanism remains unknown. Therefore, the present study aimed to reveal the regulatory mechanism of GTSE1 on SNAIL1 expression using in vitro assays performed in HCC cell models. It was demonstrated that endogenous SNAIL1 expression was downregulated and upregulated by GTSE1 overexpression or small interfering RNA-mediated knockdown, respectively. Via cycloheximide chase experiments, it was identified that GTSE1 overexpression increased the protein turnover of SNAIL1, while knockdown of GTSE1 reduced its degradation rate. Furthermore, it was demonstrated that GTSE1 overexpression induced the cytoplasmic expression of SNAIL1 using immunofluorescence and subcellular fractionation methods. The nuclear export inhibitor leptomycin B was able to decrease the cytoplasmic retention of SNAIL1 caused by GTSE1 overexpression. In addition, TGF-beta I treatment increased both the mRNA and protein expression levels of GTSE1, and decreased the protein expression level of SNAIL1 without affecting its mRNA transcription in Huh7 cells. It was also found that TGF-beta signaling could upregulate the transcription of GTSE1 expression by transactivating the Smad binding elements in the GTSE1 promoter. Moreover, the TGF-beta I-induced decrease in SNAIL1 protein expression was GTSE1-dependent in Huh7 cells. In conclusion, the current study provides a novel mechanism via which GTSE1 affects the stability of SNAIL1 by regulating its subcellular localization in HCC cells.