Destabilization of DNA G-Quadruplexes by Chemical Environment Changes during Tumor Progression Facilitates Transcription
Destabilization of DNA G-Quadruplexes by Chemical Environment Changes during Tumor Progression Facilitates Transcription
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DOI：
10.1021/jacs.7b09449
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发表时间：
2018-01-17
影响因子：
15
通讯作者：
Sugimoto, Naoki
中科院分区：
文献类型：
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作者：
Tateishi-Karimata, Hisae;Kawauchi, Keiko;Sugimoto, Naoki
DNA G-四链体的形成对周围条件，特别是K+浓度高度敏感。由于K+通道的过度表达，恶性癌细胞具有比正常细胞低得多的K+浓度;因此，G-四链体在癌细胞中可能是不稳定的。在这里，我们物理化学研究如何在体外细胞内化学环境的变化和细胞影响四链体的形成和转录在肿瘤的进展。在体外，稳定的G-四链体的形成抑制在含有150 mM KCl的溶液中的转录（正常条件）。随着K（+）浓度降低，其降低G-四链体稳定性，从具有G-四链体形成潜力的模板的转录物产生增加。在正常细胞中，转录产物的趋势与体外实验相似，转录效率与G-四链体稳定性呈负相关。有趣的是，在Ras转化的高转移性乳腺癌细胞（MDA-MB-231）中，从具有G-四链体形成潜力的模板产生的转录水平高于未转化的对照IMF-7细胞。此外，在加入靶向KCNH 1 mRNA的siRNA后，从G-四链体形成模板产生的转录物的量减少，KCNH 1 mRNA编码钾电压门控通道亚家族H成员1（K（v）10.1）。重要的是，在细胞中使用G-四链体结合抗体通过免疫荧光观察到肿瘤进展期间的G-四链体解离。这些结果表明，在正常细胞中，r离子通过稳定G-四链体结构来减弱某些癌基因的转录。我们的研究结果提供了深入了解肿瘤进展过程中某些富含G基因过表达的新机制。
DNA G-quadruplex formation is highly responsive to surrounding conditions, particularly K+ concentration. Malignant cancer cells have a much lower K+ concentration than normal cells because Of overexpression of a K+ channel; thus, G-quadruplexes may be unstable in cancer cells. Here, we physicothemically investigated how changes in intracellular chemical environments in vitro and in cells influence quadruplex formation and transcription during tumor progression. In vitro, the stable G-quadruplex formation inhibits transcription in a solution containing 150 mM KCl (normal condition). As K(+ )concentration decreases, which decreases G-quadimplex Stability, transcript production from templates with G-quadruplex-forming potential increases. In normal cells, the trend in transcript produetions: was similar to that in in vitro experiments, with transcription efficiency inversely correlated with G-quadruplex stability. Interestingly, higher transcript levels were produced from templates with G-quadruplex-forming potential in Ras-transformed and highly metastatic breast cancer cells (MDA-MB-231) than in nontransformed and control IMF-7 cells. Moreover, the amount of transcript produced from G-quadruplex-forming templates decreased, upon addition of siRNA targeting KCNH1 mRNA, which encodes a Potassium voltage-gated channel subfamily H member 1 (K(v)10.1). Importantly, G-quadruplex dissociation during tumor progression was observed by immunofluorescence using a G-quadruplex-binding antibody in cells. These results suggest that in normal cells, r ions attenuate the transcription of certain oncogenes by stabilizing G-quadruplex structures. Our findings provide insight into the novel mechanism of overexpression of certain G-rich genes during tumor progression.