Subcellular localization of the camptothecin analogues, topotecan and gimatecan
Subcellular localization of the camptothecin analogues, topotecan and gimatecan
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DOI：
10.1016/j.bcp.2003.10.034
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发表时间：
2004-03-15
影响因子：
5.8
通讯作者：
Zunino, F
中科院分区：
文献类型：
--
作者：
Croce, AC;Bottiroli, G;Zunino, F
已报道喜树碱衍生物的亲脂性改善内酯环的稳定性并有利于快速摄取和细胞内积累。最近，开发了一系列在7位取代的亲脂性喜树碱，并基于一些有利的特征，包括强效细胞毒性和缺乏乳腺癌耐药相关蛋白（BCRP）识别的独特特征，选择gimatecan（ST 1481）进行临床开发。在这项工作中，该化合物的固有荧光特性被利用来研究其细胞内的处置相比，水溶性喜树碱，拓扑替康（TPT），在HT-29结肠癌细胞和亚系，HT-29/Mit，选择耐米托蒽醌和过表达BCRP。该研究是在单细胞水平上进行的显微荧光光谱和荧光图像分析。结果表明TPT ST 1481的亚细胞定位完全不同，因为TPT主要定位于线粒体，而gimatecan表现出溶酶体定位。gimatecan处理的细胞中DNA损伤的持续性增加与溶酶体代表活性药物的储存的解释一致。与在HT-29细胞和米托蒽醌耐药亚系中表现出相似定位的gimatecan相反，TPT的细胞药代动力学受到耐药亚系中BCRP蛋白过表达的显著影响。总之，目前的结果表明一个完全不同的行为的两个喜树碱表明，除了细胞内积累，亚细胞分布发挥了作用，其细胞毒性的效力，并有助于其药理学特征。(C)2003年爱思唯尔公司All rights reserved.
Lipophilicity of camptothecins derivatives has been reported to improve the stability of the lactone ring and to favor rapid uptake and intracellular accumulation. Recently, a novel series of lipophilic camptothecins substituted at position 7 was developed, and gimatecan (ST1481) was selected for clinical development on the basis of some favorable features, including potent cytotoxicity and the unique feature of the lack of recognition by breast cancer resistance-associated protein (BCRP). In this work the intrinsic fluorescence properties of this compound were exploited to investigate its intracellular disposition in comparison with the water-soluble camptothecin, topotecan (TPT), in HT-29 colon carcinoma cells and in a subline, HT-29/Mit, selected for resistance to mitoxantrone and overexpressing BCRP. The study was performed at single-cell level by means of microspectrofluorometry and fluorescence image analysis. The results indicated a quite different subcellular localization of TPT ST1481, since TPT localized mainly in mitochondria, whereas gimatecan exhibited a lysosomal localization. An increased persistence of DNA damage in gimatecan-treated cells was consistent with the interpretation that lysosomes represent a store of active drug. In contrast to gimatecan, which showed a similar localization in HT-29 cells and in the mitoxantrone-resistant subline, the cellular pharmacokinetic of TPT was markedly influenced by overexpression of BCRP protein in the resistant subline. In conclusion, the present results indicating a quite different behavior of the two camptothecins suggest that, apart from intracellular accumulation, subcellular distribution plays a role in their cytotoxic potency and contributes to their pharmacological features. (C) 2003 Elsevier Inc. All rights reserved.