Jekunen A P, Hom D K, Alcaraz J E, Eastman A, Howell S B
Department of Medicine, University of California, San Diego, La Jolla 92093-0812.
Cancer Res. 1994 May 15;54(10):2680-7.
The cellular pharmacology of the tritium-labeled cisplatin analogue dichloro(ethylenediamine)platinum(II) ([3H]DEP) was compared in cisplatin-sensitive 2008 and resistant 2008/C13*5.25 human ovarian carcinoma cells. The cellular content of total [3H], ultrafiltrable [3H], and free native [3H]DEP was measured during and following incubation with 5 microM [3H]DEP. While the rate constant for [3H]DEP uptake in the resistant cells was reduced to 25% of that in the sensitive cells, DNA intrastrand adduct formation was reduced even further to 11%, indicating the presence of defects in both uptake and the ability of intracellular drug to access or react with DNA. The latter could not be accounted for by enhanced repair. Together, these defects were sufficient to account for the 11-fold level of resistance. At steady state, the intracellular to extracellular concentration ratio for native [3H]DEP was 7.7 in the sensitive cells and 11.7 in the resistant cells, suggesting the presence of a trapping or concentrative mechanism. Thus, despite the slower initial influx, the resistant cells eventually accumulated more free [3H]DEP than the sensitive cells. We conclude that the resistant phenotype in these cells is accounted for primarily by impaired uptake and decreased reaction of [3H]DEP with DNA rather than by changes in efflux or DNA repair.
在顺铂敏感的2008细胞和耐药的2008/C13*5.25人卵巢癌细胞中比较了氚标记的顺铂类似物二氯（乙二胺）铂（II）（[3H]DEP）的细胞药理学。在用5微摩尔[3H]DEP孵育期间及之后，测量了总[3H]、可超滤[3H]和游离天然[3H]DEP的细胞含量。虽然耐药细胞中[3H]DEP摄取的速率常数降至敏感细胞中的25%，但DNA链内加合物的形成甚至进一步降至11%，表明在摄取以及细胞内药物与DNA接触或反应的能力方面均存在缺陷。后者不能用增强的修复来解释。这些缺陷共同足以解释11倍的耐药水平。在稳态时，天然[3H]DEP在敏感细胞中的细胞内与细胞外浓度比为7.7，在耐药细胞中为11.7，表明存在捕获或浓缩机制。因此，尽管初始流入较慢，但耐药细胞最终积累的游离[3H]DEP比敏感细胞更多。我们得出结论，这些细胞中的耐药表型主要是由[3H]DEP摄取受损以及与DNA的反应减少所致，而非由流出或DNA修复的变化引起。
