Structure des Acides Nucléiques, Télomères et Evolution, Inserm U565, CNRS UMR 7196, Muséum National d'Histoire Naturelle, 43 rue Cuvier, 75231 Paris cedex 05, France.
Biochimie. 2012 Dec;94(12):2559-68. doi: 10.1016/j.biochi.2012.07.003. Epub 2012 Jul 14.
Non-canonical four-stranded structures called G-quadruplexes can form among telomere repeats during its replication. Small molecule ligands able to interact and to stabilize G-quadruplexes were shown to disrupt the binding of essential telomeric components, such as POT1 and to trigger a telomeric dysfunction associated with a delayed growth arrest in tumor cells. We describe here the chemical synthesis and the G-quadruplex binding properties of three halogenated analogs of the 360A ligand that belongs to the 2,6 pyridine dicarboxamide series. 360A is now commonly used as a benchmark both for biophysical and cellular assays as this compound was shown to display a potent affinity and selectivity for telomeric G-quadruplex DNA over duplex DNA and to induce delayed growth inhibition in HT1080 tumor cell line. Two biophysical assays indicate that, in most cases, the presence of the halogen atom seems to slightly improve the interaction with the telomeric quadruplex. For stability reasons, the bromo derivative (360A-Br) was selected for the cellular assays. Since POT1 participates to the fine tuning of the C-strand end resection during telomere replication, we investigated the effect of 360A-Br to alter the terminal nucleotide composition of XpYp telomere in HT1080 cells using C-STELA. HT1080 cells treated for up to 24 days with 360A-Br presented some minor but significant variations of C-strand terminal nucleotide composition, also observed with a partial siRNA depletion of POT1. The relevance of these minor modifications of the telomeric C-strand resection induced by 360A-Br in HT1080 cells are discussed.
非典型的四链结构称为 G-四链体，可以在端粒重复序列复制过程中形成。已经证明，能够相互作用并稳定 G-四链体的小分子配体能够破坏必需的端粒成分（如 POT1）的结合，并引发与肿瘤细胞生长延迟相关的端粒功能障碍。我们在这里描述了属于 2,6-吡啶二甲酰胺系列的 360A 配体的三个卤代类似物的化学合成和 G-四链体结合特性。360A 现在通常被用作生物物理和细胞测定的基准，因为该化合物显示出对端粒 G-四链体 DNA 相对于双链 DNA 的强亲和力和选择性，并在 HT1080 肿瘤细胞系中诱导生长延迟抑制。两种生物物理测定表明，在大多数情况下，卤素原子的存在似乎略微改善了与端粒四联体的相互作用。出于稳定性原因，选择溴代衍生物（360A-Br）进行细胞测定。由于 POT1 参与端粒复制过程中 C 链末端切除的微调，我们使用 C-STELA 研究了 360A-Br 对改变 HT1080 细胞中 XpYp 端粒末端核苷酸组成的影响。用 360A-Br 处理长达 24 天的 HT1080 细胞呈现出一些较小但显着的 C 链末端核苷酸组成的变化，这些变化也观察到 POT1 的部分 siRNA 耗竭。讨论了 360A-Br 在 HT1080 细胞中诱导的端粒 C 链切除的这些微小修饰的相关性。
