Lindauer E, Holler E
Institut für Biophysik und Physikalische Biochemie, Universität Regensburg, Germany.
Biochem Pharmacol. 1996 Jul 12;52(1):7-14. doi: 10.1016/0006-2952(96)00106-2.
We have investigated whether or not the cellular content of reactive platinum, aside from total cellular and DNA-bound platinum, is a measure of the growth inhibitory potential of a given platinum complex. Human MCF-7 breast cancer cells, after treatment with cisplatin [cis-diamminedichloroplatinum(II)] and several 1,2-diphenylethylenediamineplatinum(II) complexes at a fixed dose of 3 microM, were analyzed for their contents of platinum in total cells, isolated nuclei, chromosomal DNA, and the cellular pool of reactive platinum, and compared with ED50-values. Platinum was measured by atomic absorption. Reactive platinum was identified after its reaction with calf thymus DNA that had been added to the cells before their lysis. The amounts of platinum binding to chromosomal DNA were related to previously established ED50-values, and such a correlation could not be found for platinum in total cells, nuclei, and, especially, reactive platinum. The observed differences in the platinum contents of DNA were referred to variations in the rate of adduct formation rather than repair because two representative platinum complexes were indistinguishable by their effects on the chloramphenicol acetyltransferase (EC 2.3.1.28) transfection system. One of the other platinum complexes accumulated, showing an increased growth inhibition in support of this interpretation with regard to the other platinum complexes. During prolonged treatment of MCF-7 cells with the platinum(II) complexes, pools of reactive platinum were found to persist even after drug depletion in the culture medium. This suggested a hitherto unrecognized cellular storage and availability of reactive platinum.
我们已经研究了除细胞总铂含量和与DNA结合的铂含量之外，反应性铂的细胞内含量是否可作为给定铂配合物生长抑制潜力的一种衡量指标。用顺铂[顺式二氯二氨合铂（II）]和几种1,2 - 二苯基乙二胺铂（II）配合物以3 microM的固定剂量处理人MCF - 7乳腺癌细胞后，分析了其在总细胞、分离的细胞核、染色体DNA以及反应性铂的细胞池中的铂含量，并与ED50值进行比较。通过原子吸收法测量铂含量。在细胞裂解前加入小牛胸腺DNA，使其与反应性铂反应后鉴定反应性铂。与染色体DNA结合的铂量与先前确定的ED50值相关，而在总细胞、细胞核尤其是反应性铂中的铂含量未发现这种相关性。观察到的DNA中铂含量的差异归因于加合物形成速率的变化而非修复，因为两种代表性的铂配合物对氯霉素乙酰转移酶（EC 2.3.1.28）转染系统的影响无法区分。其他铂配合物之一会积累，这表明就其他铂配合物而言，其生长抑制作用增强支持了这一解释。在用铂（II）配合物对MCF - 7细胞进行长时间处理期间，发现即使培养基中的药物耗尽，反应性铂池仍会持续存在。这表明存在一种迄今未被认识到的反应性铂的细胞储存和可用性。
