Laboratory of Biochemistry and Biophysics, College of Life Sciences, Wuhan University, Wuhan, P R China.
J Am Chem Soc. 2011 Sep 28;133(38):15036-44. doi: 10.1021/ja204326w. Epub 2011 Sep 2.
Inhibition of telomerase activity through stabilizing telomere G-quadruplex with small chemical ligands is emerging as a novel strategy for cancer therapy. For the large number of ligands that have been reported to inhibit telomerase activity, it is difficult to validate the contribution of G-quadruplex stabilization to the overall inhibition. Using a modified telomere repeat amplification protocol (TRAP) method to differentiate the telomere G-quadruplex independent effect from dependent ones, we analyzed several ligands that have high affinity and/or selectivity to telomere G-quadruplex. Our results show that these ligands effectively inhibited telomerase activity in the absence of telomere G-quadruplex. The expected G-quadruplex-dependent inhibition was only obvious for the cationic ligands at low K(+) concentration, but it dramatically decreased at physiological concentration of K(+). These observations demonstrate that the ligands are much more than G-quadruplex stabilizers with a strong G-quadruplex-irrelevant off-target effect. They inhibit telomerase via multiple pathways in which stabilization of telomere G-quadruplex may only make a minor or neglectable contribution under physiologically relevant conditions depending on the stability of telomere G-quadruplex under ligand-free conditions.
通过小分子化学配体稳定端粒 G-四链体来抑制端粒酶活性，正成为一种癌症治疗的新策略。对于大量报道的能抑制端粒酶活性的配体来说，很难验证 G-四链体稳定对整体抑制作用的贡献。我们使用改良的端粒重复扩增检测（TRAP）方法，从依赖和不依赖端粒 G-四链体的效应来区分，分析了几种对端粒 G-四链体具有高亲和力和/或选择性的配体。结果表明，这些配体在没有端粒 G-四链体的情况下能有效地抑制端粒酶活性。只有在低浓度 K+的情况下，预期的依赖于 G-四链体的抑制才明显，而在生理浓度的 K+下，这种抑制作用显著降低。这些观察结果表明，这些配体远不止是 G-四链体稳定剂，它们具有很强的非 G-四链体非靶标效应。它们通过多种途径抑制端粒酶，其中在生理相关条件下，端粒 G-四链体的稳定可能只做出较小或可忽略的贡献，这取决于在无配体条件下端粒 G-四链体的稳定性。
