James Lloyd R A, Xu Zhi-Qiang, Sluyter Ronald, Hawksworth Emma L, Kelso Celine, Lai Barry, Paterson David J, de Jonge Martin D, Dixon Nicholas E, Beck Jennifer L, Ralph Stephen F, Dillon Carolyn T
Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia.
Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; School of Biological Sciences, University of Wollongong, Wollongong, NSW 2522, Australia; Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia.
J Inorg Biochem. 2015 Jan;142:28-38. doi: 10.1016/j.jinorgbio.2014.09.013. Epub 2014 Sep 28.
Gold(I) complexes are an important tool in the arsenal of established approaches for treating rheumatoid arthritis (RA), while some recent studies have suggested that gold nanoparticles (Au NPs) may also be therapeutically efficacious. These observations prompted the current biological studies involving gold(I) anti-RA agents and Au NPs, which are aimed towards improving our knowledge of how they work. The cytotoxicity of auranofin, aurothiomalate, aurothiosulfate and Au NPs towards RAW264.7 macrophages was evaluated using the MTT assay, with the former compound proving to be the most toxic. The extent of cellular uptake of the various gold agents was determined using graphite furnace atomic absorption spectrometry, while their distribution within macrophages was examined using microprobe synchrotron radiation X-ray fluorescence spectroscopy. The latter technique showed accumulation of gold in discrete regions of the cell, and co-localisation with sulfur in the case of cells treated with aurothiomalate or auranofin. Electrospray ionization mass spectrometry was used to characterize thioredoxin reductase (TrxR) in which the penultimate selenocysteine residue was replaced by cysteine. Mass spectra of solutions of TrxR and aurothiomalate, aurothiosulfate or auranofin showed complexes containing bare gold atoms bound to the protein, or protein adducts containing gold atoms retaining some of their initial ligands. These results support TrxR being an important target of gold(I) drugs used to treat RA, while the finding that Au NPs are incorporated into macrophages, but elicit little toxicity, indicates further exploration of their potential for treatment of RA is warranted.
金（I）配合物是治疗类风湿性关节炎（RA）的既定方法中的重要工具，而最近的一些研究表明金纳米颗粒（Au NPs）可能也具有治疗效果。这些观察结果促使了当前涉及金（I）抗RA药物和Au NPs的生物学研究，其目的是增进我们对它们作用方式的了解。使用MTT法评估了金诺芬、硫代苹果酸金钠、硫代硫酸金钠和Au NPs对RAW264.7巨噬细胞的细胞毒性，结果表明前一种化合物毒性最大。使用石墨炉原子吸收光谱法测定了各种金制剂的细胞摄取程度，同时使用微探针同步辐射X射线荧光光谱法检查了它们在巨噬细胞内的分布。后一种技术显示金在细胞的离散区域积累，在用硫代苹果酸金钠或金诺芬处理的细胞中，金与硫共定位。使用电喷雾电离质谱法对硫氧还蛋白还原酶（TrxR）进行了表征，其中倒数第二个硒代半胱氨酸残基被半胱氨酸取代。TrxR与硫代苹果酸金钠、硫代硫酸金钠或金诺芬溶液的质谱显示，存在与蛋白质结合的裸金原子组成的配合物，或含有保留一些初始配体的金原子的蛋白质加合物。这些结果支持TrxR是用于治疗RA的金（I）药物的重要靶点，而Au NPs被巨噬细胞摄取但几乎不产生毒性这一发现表明有必要进一步探索其治疗RA的潜力。
