P53 and Protein Phosphorylation Regulate the Oncogenic Role of Epithelial Cell Transforming 2 (ECT2).
P53 and Protein Phosphorylation Regulate the Oncogenic Role of Epithelial Cell Transforming 2 (ECT2).
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DOI：
10.12659/msm.905388
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发表时间：
2017-06-27
期刊：
影响因子：
--
通讯作者：
Liu Y
中科院分区：
文献类型：
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作者：
Chen Y;Tian P;Liu Y
胃癌是世界范围内第二大癌症相关死亡原因，但对晚期或转移性胃癌的治疗进展甚微。胃癌是高度异质性的，需要更多的研究来阐明转移机制。上皮细胞转化因子2（ECT 2）在胃癌组织中表达上调，但其信号转导机制尚不清楚。在这项研究中，我们使用Western blot分析比较ECT 2在2个GC细胞系：MKN 1和MKN 45中的表达水平。采用基因突变和转染的方法研究ECT 2在胃癌细胞中的致癌机制。ECT 2在MKN 1中的表达水平高于MKN 45。免疫印迹结果显示，p53-WT抑制MKN 1表达，但p53-突变体增强MKN 1表达。此外，体外实验表明，ECT 2正调控GC细胞的增殖和侵袭。为了更好地探索ECT 2促进胃癌进展的机制，我们引入了ECT 2的定点突变体，发现磷酸化模拟突变体T359 D增强了其致癌活性。与此相反，RhoA的激活被抑制在细胞转染ECT 2磷酸缺陷突变体T359 A。我们发现上皮细胞生物标志物E-cadherin被ECT 2-T359 D下调，突出了磷酸化在调节上皮-间充质转化中的作用。我们的研究结果证实p53是胃癌细胞中一种新的ECT 2上游信号分子，ECT 2的翻译后修饰在调节肿瘤的发生和发展中起重要作用。
Gastric cancer (GC) is the second leading cause of cancer-related death worldwide, but little progress has been achieved in the treatment of advanced or metastatic GC. GC is highly heterogeneous and more studies are needed to elucidate the metastatic mechanisms. Epithelial cell transforming 2 (ECT2) has been reported to be up-regulated in GC tissues, but its signaling mechanisms remain unclear. In this study, we used Western blot analysis to compare the expression level of ECT2 in 2 GC cell lines: MKN1 and MKN45. Mutagenesis and transfections were conducted to investigate the oncogenic mechanisms of ECT2 in GC cells. ECT2 was expressed at higher levels in MKN1 than in MKN45. Immunoblotting results showed that MKN1 expression was suppressed by p53-WT but was enhanced by p53-mutant. In addition, in vitro experiments showed that ECT2 positively regulated the proliferation and invasion of GC cells. To better explore the mechanisms of ECT2 in promoting GC progression, we introduced site-directed mutants of ECT2, and found that the phosphor-mimic mutant T359D enhanced its oncogenic activity. In contrast, activation of RhoA was inhibited in cells transfected with ECT2 phosphor-deficient mutant T359A. We found that the epithelial cell biomarker E-cadherin was down-regulated by ECT2-T359D, highlighting the role of phosphorylation in regulating epithelial-mesenchymal transition. Our results identified p53 as a novel up-stream signaling molecule of ECT2 in GC cells, and the post-translational modifications of ECT2 play important roles in regulating cancer development and progression.