Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , United States.
J Am Chem Soc. 2018 Apr 25;140(16):5612-5624. doi: 10.1021/jacs.8b02271. Epub 2018 Apr 17.
Rhodium metalloinsertors are a unique set of metal complexes that bind specifically to DNA base pair mismatches in vitro and kill mismatch repair (MMR)-deficient cells at lower concentrations than their MMR-proficient counterparts. A family of metalloinsertors containing rhodium-oxygen ligand coordination, termed "Rh-O" metalloinsertors, has been prepared and shown to have a significant increase in both overall potency and selectivity toward MMR-deficient cells regardless of structural changes in the ancillary ligands. Here we describe DNA-binding and cellular studies with the second generation of Rh-O metalloinsertors in which an ancillary ligand is varied in both steric bulk and lipophilicity. These complexes, of the form [Rh(L)(chrysi)(PPO)], all include the O-containing PPO ligand (PPO = 2-(pyridine-2-yl)propan-2-ol) and the aromatic inserting ligand chrysi (5,6-chrysene quinone diimine) but differ in the identity of their ancillary ligand L, where L is a phenanthroline or bipyridyl derivative. The Rh-O metalloinsertors in this family all show micromolar binding affinities for a 29-mer DNA hairpin containing a single CC mismatch. The complexes display comparable lipophilic tendencies and p K values of 8.1-9.1 for dissociation of an imine proton on the chrysi ligand. In cellular proliferation and cytotoxicity assays with MMR-deficient cells (HCT116O) and MMR-proficient cells (HCT116N), the complexes containing the phenanthroline-derived ligands show highly selective cytotoxic preference for the MMR-deficient cells at nanomolar concentrations. Using mass spectral analyses, it is shown that the complexes are taken into cells through a passive mechanism and exhibit low accumulation in mitochondria, an off-target organelle that, when targeted by parent metalloinsertors, can lead to nonselective cytotoxicity. Overall, these Rh-O metalloinsertors have distinct and improved behavior compared to previous generations of parent metalloinsertors, making them ideal candidates for further therapeutic assessment.
铑金属插入剂是一组独特的金属配合物，它们在体外特异性结合 DNA 碱基对错配，并以低于其错配修复 (MMR) 功能正常对应物的浓度杀死 MMR 缺陷细胞。已经制备了一类含有铑-氧配体配位的金属插入剂，称为“Rh-O”金属插入剂，并已证明其对 MMR 缺陷细胞的整体效力和选择性均有显著提高，而与辅助配体的结构变化无关。在这里，我们描述了第二代 Rh-O 金属插入剂的 DNA 结合和细胞研究，其中辅助配体的空间位阻和疏水性都发生了变化。这些配合物的形式为 [Rh(L)(chrysi)(PPO)]，均包含含氧的 PPO 配体 (PPO = 2-(吡啶-2-基)丙-2-醇) 和芳香插入配体 chrysi(5,6- 二氢萘醌二亚胺)，但辅助配体 L 的身份不同，L 是菲咯啉或联吡啶衍生物。该系列中的 Rh-O 金属插入剂均对含有单个 CC 错配的 29 -mer DNA 发夹显示出微摩尔结合亲和力。这些配合物显示出可比的亲脂性趋势和 chrysi 配体上亚胺质子解离的 p K 值为 8.1-9.1。在 MMR 缺陷细胞 (HCT116O) 和 MMR 功能正常细胞 (HCT116N) 的细胞增殖和细胞毒性测定中，含有菲咯啉衍生配体的配合物在纳摩尔浓度下对 MMR 缺陷细胞表现出高度选择性的细胞毒性偏好。通过质谱分析表明，这些配合物通过被动机制被带入细胞，并在细胞内线粒体中低积累，线粒体是一种非靶细胞器，当被母体金属插入剂靶向时，可能导致非选择性细胞毒性。总体而言，与前几代母体金属插入剂相比，这些 Rh-O 金属插入剂具有独特且改善的行为，使其成为进一步治疗评估的理想候选物。
