Reduced or Diminished Stabilization of the Telomere G-Quadruplex and Inhibition of Telomerase by Small Chemical Ligands under Molecular Crowding Condition
Reduced or Diminished Stabilization of the Telomere G-Quadruplex and Inhibition of Telomerase by Small Chemical Ligands under Molecular Crowding Condition
复制标题
分子拥挤条件下小化学配体降低或减弱端粒 G-四链体的稳定性和端粒酶的抑制
DOI：
10.1021/ja9010749
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发表时间：
2009-08-05
影响因子：
15
通讯作者：
Tan, Zheng
中科院分区：
文献类型：
--
作者：
Chen, Zhao;Zheng, Ke-wei;Tan, Zheng
人类细胞中的端粒DNA在每一轮DNA复制过程中都会缩短。在癌细胞中，端粒缩短通过端粒酶或替代延长端粒(ALT)机制来补偿，以维持细胞分裂潜力。富含G的端粒DNA链可以折叠成G-四链结构，扰乱这两个过程。因此，通过化学配体稳定G-四链是一种很有前途的抗癌策略。到目前为止，对这类配体的体外研究仅在稀溶液中进行。然而，细胞内环境高度拥挤，充满了生物分子。G-四链配体在分子拥挤条件下的行为是其体内抗癌作用的关键。在这项工作中，我们研究了几种配体在稀释和拥挤条件下稳定端粒G-四链和抑制端粒酶的能力。令人惊讶的是，在拥挤的条件下，配体变得明显不那么有效，甚至失去了稳定G-四链和抑制端粒酶的能力。我们的数据将这一结果归因于配体与G-四链体的结合亲和力降低，这是由于与分子拥挤相关的介质的水活度降低和粘度增加所致。这种效应与G-四链结构、阳离子和配基种类等其他因素的影响无关，也超过了这些因素的影响。我们的工作说明了一种可能性，即细胞内的分子拥挤可能会降低或限制配体的效力，尽管它们在稀溶液中可能是有效的，从而有力地证明了在更生理相关的条件下评估配体的必要性，并考虑到这一点来设计药物。
Telomere DNA in human cells shortens during each round of DNA replication. In cancer cells, telomere shortening is compensated by telomerase or the alternative lengthening of telomere (ALT) mechanism to maintain cell division potential. The G-rich strand of telomere DNA can fold into a G-quadruplex structure and disrupt these two processes. Therefore, stabilization of the G-quadruplex by chemical ligands is emerging as a promising anticancer strategy. So far, in vitro studies on such ligands are exclusively carried out in dilute solutions. However, the intracellular environment is highly crowded with biomolecules. How G-quadruplex ligands behave under molecular crowding condition is critical for their in vivo anticancer effect. In this work, we studied several ligands for their ability to stabilize the telomere G-quadruplex and inhibit telomerase under both dilute and crowding conditions. Surprisingly, the ligands became significantly less effective or even lost the ability to stabilize the G-quadruplex and inhibit telomerase under crowding conditions. Our data attributed this consequence to the decreased binding affinity of ligands to the G-quadruplex as a result of reduced water activity and increased viscosity of the medium associated with molecular crowding. This effect is irrelevant to and overweighs the influences from other factors such as the G-quadruplex structure, cation, and ligand species. Our work illustrates a possibility that molecular crowding inside cells may reduce or limit the potency of ligands although they may be effective in dilute solution, thus strongly arguing for the necessity of evaluating ligands under more physiologically relevant conditions and designing drugs with this concern in mind.