Wang Ling, Liu Jingqi, Chen Feng, Li Guodong, Wang Jing, Chan Daniel Shiu-Hin, Wong Chun-Yuen, Wang Wanhe, Leung Chung-Hang
State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, 999078, China.
Institute of Medical Research, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China.
Bioconjug Chem. 2023 Oct 18;34(10):1727-1737. doi: 10.1021/acs.bioconjchem.3c00267. Epub 2023 Sep 26.
Glutathione -transferase is heterogeneously expressed in breast cancer cells and is therefore emerging as a potential diagnostic biomarker for studying the heterogeneity of breast cancers. However, available fluorescent probes for GSTs depend heavily on GSTs-catalyzed glutathione (GSH) nucleophilic substitution reactions, making them susceptible to interference by the high concentration of nucleophilic species in the cellular environment. Moreover, the functions of subcellular GSTs are generally overlooked due to the lack of suitable luminescence probes. Herein, we report a highly selective affinity-based luminescence probe for GST in breast cancer cells through tethering a GST inhibitor, ethacrynic acid, to an iridium(III) complex. Compared to activity-based probes which require the use of GSH, this probe could image GST-pi in the mitochondria by directly adducting to GST-pi (or potentially GST-pi/GS) in living cells. Probe possesses desirable photophysical properties including a lifetime of 911 ns, a Stokes shift of 343 nm, and high photostability. The "turn on" luminescence mode of the probe enables highly selective detection of the GST with a limit of detection of 1.01 μM, while its long emission lifetime allows sensitive detection in organic dye-spiked autofluorescence samples by a time-resolved mode. The probe was further applied to specifically and quantitatively visualize MDA-MB-231 cells via specific binding to mitochondrial GST, and could differentiate breast cell lines based on their expression levels of GST. To the best of our knowledge, this probe is the first affinity-based iridium(III) imaging probe for the subcellular GST. Our work provides a valuable tool for unmasking the diverse roles of a subcellular GST in living systems, as well as for studying the heterogeneity of breast cancers.
谷胱甘肽转移酶在乳腺癌细胞中呈异质性表达，因此正成为研究乳腺癌异质性的一种潜在诊断生物标志物。然而，现有的谷胱甘肽转移酶荧光探针严重依赖谷胱甘肽转移酶催化的谷胱甘肽（GSH）亲核取代反应，这使得它们容易受到细胞环境中高浓度亲核物质的干扰。此外，由于缺乏合适的发光探针，亚细胞谷胱甘肽转移酶的功能通常被忽视。在此，我们通过将谷胱甘肽转移酶抑制剂依他尼酸连接到铱（III）配合物上，报道了一种用于乳腺癌细胞中谷胱甘肽转移酶的高选择性基于亲和力的发光探针。与需要使用谷胱甘肽的基于活性的探针相比，该探针可以通过直接与活细胞中的谷胱甘肽转移酶 - π（或潜在的谷胱甘肽转移酶 - π/谷胱甘肽）加合来对线粒体中的谷胱甘肽转移酶 - π进行成像。探针具有理想的光物理性质，包括911纳秒的寿命、343纳米的斯托克斯位移和高光稳定性。探针的“开启”发光模式能够以1.01微摩尔的检测限对谷胱甘肽转移酶进行高选择性检测，而其长发射寿命允许通过时间分辨模式在有机染料掺杂的自发荧光样品中进行灵敏检测。该探针进一步应用于通过与线粒体谷胱甘肽转移酶的特异性结合来特异性和定量地可视化MDA - MB - 231细胞，并且可以根据乳腺癌细胞系中谷胱甘肽转移酶的表达水平对其进行区分。据我们所知，该探针是第一个用于亚细胞谷胱甘肽转移酶的基于亲和力的铱（III）成像探针。我们的工作为揭示亚细胞谷胱甘肽转移酶在生命系统中的多种作用以及研究乳腺癌的异质性提供了一个有价值的工具。
