Molecular and Environmental Sciences Group, Department of Geological Sciences, College of Arts and Science, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan S7N 5E2, Canada.
Metallomics. 2020 Dec 23;12(12):1979-1994. doi: 10.1039/d0mt00222d.
8-Hydroxyquinolines (8HQs) comprise a family of metal-binding compounds that have been used or tested for use in numerous medicinal applications, including as treatments for bacterial infection, Alzheimer's disease, and cancer. Two key 8HQs, CQ (5-chloro-7-iodo-8-hydroxyquinoline) and PBT2 (2-(dimethylamino)methyl-5,7-dichloro-8-hydroxyquinoline), have drawn considerable interest and have been the focus of many studies investigating their in vivo properties. These drugs have been described as copper and zinc ionophores because they do not cause metal depletion, as would be expected for a chelation mechanism, but rather cellular accumulation of these ions. In studies of their anti-cancer properties, CQ has been proposed to elicit toxic intracellular copper accumulation and to trigger apoptotic cancer cell death through several possible pathways. In this study we used synchrotron X-ray fluorescence imaging, in combination with biochemical assays and light microscopy, to investigate 8HQ-induced alterations to metal ion homeostasis, as well as cytotoxicity and cell death. We used the bromine fluorescence from a bromine labelled CQ congener (5,7-dibromo-8-hydroxyquinoline; B2Q) to trace the intracellular localization of B2Q following treatment and found that B2Q crosses the cell membrane. We also found that 8HQ co-treatment with Cu(ii) results in significantly increased intracellular copper and significant cytotoxicity compared with 8HQ treatments alone. PBT2 was found to be more cytotoxic, but a weaker Cu(ii) ionophore than other 8HQs. Moreover, treatment of cells with copper in the presence of CQ or B2Q resulted in copper accumulation in the nuclei, while PBT2-guided copper was distributed near to the cell membrane. These results suggest that PBT2 may be acting through a different mechanism than that of other 8HQs to cause the observed cytotoxicity.
8-羟基喹啉（8HQs）是一类金属结合化合物，已被用于或测试用于多种医学应用，包括治疗细菌感染、阿尔茨海默病和癌症。两种关键的 8HQs，CQ（5-氯-7-碘-8-羟基喹啉）和 PBT2（2-（二甲基氨基）甲基-5,7-二氯-8-羟基喹啉），引起了相当大的关注，并成为许多研究其体内特性的焦点。这些药物被描述为铜和锌离子载体，因为它们不会像螯合机制那样导致金属耗竭，而是导致这些离子在细胞内积累。在研究其抗癌特性时，CQ 被提出通过几种可能的途径引起有毒的细胞内铜积累，并触发细胞凋亡性癌细胞死亡。在这项研究中，我们使用同步加速器 X 射线荧光成像，结合生化测定和光学显微镜，研究 8HQ 诱导的金属离子动态平衡改变、细胞毒性和细胞死亡。我们使用溴标记的 CQ 类似物（5,7-二溴-8-羟基喹啉；B2Q）的溴荧光来追踪 B2Q 处理后的细胞内定位，发现 B2Q 穿过细胞膜。我们还发现，与单独用 8HQ 处理相比，8HQ 与 Cu（ii）共同处理会导致细胞内铜显著增加和显著的细胞毒性。与其他 8HQ 相比，PBT2 被发现更具细胞毒性，但作为 Cu（ii）离子载体的能力较弱。此外，在存在 CQ 或 B2Q 的情况下用铜处理细胞会导致铜在核内积累，而 PBT2 引导的铜分布在靠近细胞膜的地方。这些结果表明，PBT2 可能通过与其他 8HQ 不同的机制引起观察到的细胞毒性。
