Investigations using fluorescent ligands to monitor platinum(iv) reduction and platinum(ii) reactions in cancer cells
作者:Elizabeth J. New、Ran Duan、Jenny Z. Zhang、Trevor W. Hambley
DOI:10.1039/b821603g
日期:——
Coordination of the aniline containing fluorophores, coumarin 120 (C120) and coumarin 151 (C151) at the non-leaving group positions of cisplatin analogues (giving cis-[PtCl2(C120)(NH3)] and cis-[PtCl2(C151)(NH3)]) resulted in partial and complete quenching of the fluorescence, respectively. Oxidation of the coumarin 120 complex to the Pt(IV) form (cis,trans,cis-[PtCl2(OH)2(C120)(NH3)]) resulted in further quenching compared to that seen for the Pt(II) complex. The fluorescence profiles of these coumarin complexes were collected to evaluate their suitability for studying the metabolism of cisplatin-based anticancer drugs. C151 has the more suitable profile with a lower energy excitation peak and a better separation between the excitation and emission spectra. The complete damping of fluorescence on coordination to Pt(II) makes it unsuitable for monitoring the reduction process, but does allow it to be used to monitor loss of the aniline type ligand. All of the coumarin complexes revealed moderate cyotoxcities in the range 10–22 μM indicating that they are suitable models of anticancer agents. DNA dampens the fluorescence of both Pt(II) complexes and that of C120 has a much higher DNA binding affinity (10 000 M−1) than does the complex of C151 (300 M−1). Treatment of A2780 human ovarian carcinoma cells with the Pt-coumarin complexes resulted in fluorescence visible by confocal microscopy, and co-localisation studies with organelle specific dyes suggest they are concentrated in the late endosomes or lysosomes. Cells treated with the Pt(IV) complex of C120 revealed strong fluorescence and a somewhat different distribution to cells treated with the Pt(II) complex indicating reduction following uptake.
含有苯胺的荧光团,即香豆素120(C120)和香豆素151(C151),与顺铂类似物的不离去位点协同作用(得到cis-[PtCl2(C120)(NH3)]和cis-[PtCl2(C151)(NH3)])分别导致部分和完全荧光淬灭。将香豆素120复合物氧化为Pt(IV)形式(cis,trans,cis-[PtCl2(OH)2(C120)(NH3)])则导致进一步的淬灭,相比之下,Pt(II)复合物也有这种情况。收集了这些香豆素复合物的荧光光谱,以评估它们是否适合用于研究基于顺铂的抗癌药物的代谢。C151具有更合适的荧光光谱,其激发峰能量较低,且激发光谱和发射光谱之间有更好的分离。完全淬灭荧光的协同作用使其不适合用于监测还原过程,但可用于监测苯胺类配体的丢失。所有香豆素复合物在10-22μM的范围内显示出中等细胞毒性,表明它们是适合用于抗癌剂的模型。DNA抑制了两种Pt(II)复合物的荧光,而C120与DNA的结合亲和力(10000 M-1)远高于C151复合物(300 M-1)。使用顺铂-香豆素复合物处理人卵巢癌细胞A2780,通过共聚焦显微镜可观察到荧光,并与特定细胞器的染料共定位研究表明,它们主要集中在晚期内体或溶酶体中。与使用Pt(II)复合物处理的细胞相比,用C120的Pt(IV)复合物处理的细胞显示出强烈的荧光,且分布略有不同,表明在摄取后发生还原反应。