Yan Jing, Zhao Xiaoyang, Liu Bo, Yuan Ying, Guan Yifu
Department of Biochemistry and Molecular Biology, China Medical University, Shenyang, Liaoning, China.
Mol Carcinog. 2016 May;55(5):897-909. doi: 10.1002/mc.22330. Epub 2015 May 6.
Previous studies have shown that promoter regions of many proto-oncogenes can fold into G-quadruplexes, which are potentially involved in the regulation of genes. Bioinformatics analysis suggested that there was a G-rich sequence within -48 to -26 region of the human MET promoter (named Pu23WT). In this study, we proved that Pu23WT adopted an intramolecular parallel G-quadruplex structure under physiological conditions in vitro, and the cationic porphyrin TMPyP4 enhanced the stability of the Pu23WT G-quadruplex. To better understand the functions of Pu23WT in the MET expression, we performed a series of analysis on several cancer cells. Experimental data revealed that TMPyP4 treatment attenuated the expression of MET in HepG2, BGC823, and U87MG cells, resulting in the cellular proliferation inhibition, G1 phase cell cycle arrest and cell migration retardation. ChIP assay results indicated that TMPyP4 probably prohibited the Pu23WT G-quadruplex from binding to the activator Sp1, which could be one of the mechanisms that led to the transcription inhibition of MET gene. It is the first study on the G-quadruplex structure in the human MET promoter and its functions in cancer cells. We believe that this structure is a potential target for anticancer treatment.
先前的研究表明，许多原癌基因的启动子区域可折叠成G-四链体，这可能参与基因调控。生物信息学分析表明，人类MET启动子的-48至-26区域内存在一个富含G的序列（命名为Pu23WT）。在本研究中，我们证明了Pu23WT在体外生理条件下形成分子内平行G-四链体结构，并且阳离子卟啉TMPyP4增强了Pu23WT G-四链体的稳定性。为了更好地了解Pu23WT在MET表达中的功能，我们对几种癌细胞进行了一系列分析。实验数据显示，TMPyP4处理减弱了HepG2、BGC823和U87MG细胞中MET的表达，导致细胞增殖受到抑制、G1期细胞周期阻滞以及细胞迁移减缓。染色质免疫沉淀分析结果表明，TMPyP4可能阻止Pu23WT G-四链体与激活剂Sp1结合，这可能是导致MET基因转录抑制的机制之一。这是关于人类MET启动子中G-四链体结构及其在癌细胞中的功能的首次研究。我们认为这种结构是抗癌治疗的一个潜在靶点。
