Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan.
Chem Commun (Camb). 2020 Nov 4;56(85):12905-12908. doi: 10.1039/d0cc04957c. Epub 2020 Oct 8.
Macrocyclic hexaoxazoles (6OTDs) are G-quadruplex (G4) ligands, and some derivatives, such as L2H2-6OTD (1a) bearing two aminobutyl side chains, show cytotoxicity towards cancer cells. To identify the cellular target of 1a, we employed a post-target-binding strategy utilizing click reaction (Huisgen cyclization) between the azide-conjugated ligand L2H2-6OTD-Az (1b) and the cell-permeable dye CO-1 bearing a strained alkyne moiety and the BODIPY fluorophore under Cu-free conditions. We confirmed that introduction of the small azide group did not alter the physical or biological properties, including anti-cancer activity, of 1a, and we also demonstrated bias-free localization of CO-1. The post-binding visualization strategy suggested that L2H2-6OTD (1a) colocalized with RNA G4 in living cells.
大环六氧杂氮（6OTD）是 G-四链体（G4）配体，其某些衍生物，如带有两个氨丁基侧链的 L2H2-6OTD（1a），对癌细胞具有细胞毒性。为了鉴定 1a 的细胞靶标，我们采用了一种后靶结合策略，利用叠氮化物缀合配体 L2H2-6OTD-Az（1b）与具有应变炔基部分和 BODIPY 荧光团的细胞穿透性染料 CO-1 之间的点击反应（Huisgen 环化）在无铜条件下进行。我们证实，引入小的叠氮基团不会改变 1a 的物理或生物学性质，包括抗癌活性，并且我们还证明了 CO-1 的无偏定位。后结合可视化策略表明，L2H2-6OTD（1a）与活细胞中的 RNA G4 共定位。
