Multiple mechanisms confer drug resistance to mitoxantrone in the human 8226 myeloma cell line.
Multiple mechanisms confer drug resistance to mitoxantrone in the human 8226 myeloma cell line.
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发表时间：
1999-03
期刊：
影响因子：
11.2
通讯作者：
L. Hazlehurst;Nils E. Foley;M. Gleason-Guzman;M. Hacker;A. Cress;L. Greenberger;M. C. D. Jong;W. Dalton
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文献类型：
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作者：
L. Hazlehurst;Nils E. Foley;M. Gleason-Guzman;M. Hacker;A. Cress;L. Greenberger;M. C. D. Jong;W. Dalton
体外耐药性的选择可导致复杂的表型，同时或依次出现一种以上的耐药机制。我们研究了在人骨髓瘤细胞系8226中米托蒽醌选择过程中出现的耐药机制。一种新的运输机制出现在早期的选择过程中，这是与10倍的耐药米托蒽醌在8226/MR 4细胞系。细胞内药物浓度的减少是ATP依赖性的，哇巴因不敏感。8226/MR 4细胞系对荧光氮杂蒽吡唑BBR 3390具有34倍交叉耐药性。对BBR 3390的耐药性与细胞内药物浓度降低50%一致。使用BBR 3390的共聚焦显微镜显示耐药细胞系的核质比降低了64%。米托蒽醌和BBR 3390的细胞内药物浓度的降低可被一种新的化学增敏剂烟曲霉素C逆转。相反，烟曲霉素C对P-糖蛋白阳性的8226/DOX 6细胞系对米托蒽醌或BBR 3390的耐药性没有影响。将8226细胞系中对米托蒽醌的抗性程度从10倍增加到37倍（8226/MR 20）并没有进一步降低细胞内药物浓度。然而，与亲本药物敏感细胞系相比，8226/MR 20细胞系表现出拓扑异构酶II β和α表达分别降低88%和70%。在低水平耐药的8226/MR 4细胞系中未观察到拓扑异构酶表达和活性的降低。这些数据表明，低水平的米托蒽醌耐药是由于存在一种新的，能量依赖性药物外排泵类似于P-糖蛋白和多药耐药相关蛋白。通过用烟曲霉素C阻断药物外排来抑制耐药性，应允许在癌细胞系或临床肿瘤样品中对这种新型转运蛋白进行功能分析。对米托蒽醌的耐药性增加可能是由于细胞内药物蓄积减少、细胞核/细胞质药物分布改变和拓扑异构酶II活性改变所致。
Selection for in vitro drug resistance can result in a complex phenotype with more than one mechanism of resistance emerging concurrently or sequentially. We examined emerging mechanisms of drug resistance during selection with mitoxantrone in the human myeloma cell line 8226. A novel transport mechanism appeared early in the selection process that was associated with a 10-fold resistance to mitoxantrone in the 8226/MR4 cell line. The reduction in intracellular drug concentration was ATP-dependent and ouabain-insensitive. The 8226/MR4 cell line was 34-fold cross-resistant to the fluorescent aza-anthrapyrazole BBR 3390. The resistance to BBR 3390 coincided with a 50% reduction in intracellular drug concentration. Confocal microscopy using BBR 3390 revealed a 64% decrease in the nuclear:cytoplasmic ratio in the drug-resistant cell line. The reduction in intracellular drug concentration of both mitoxantrone and BBR 3390 was reversed by a novel chemosensitizing agent, fumitremorgin C. In contrast, fumitremorgin C had no effect on resistance to mitoxantrone or BBR 3390 in the P-glycoprotein-positive 8226/DOX6 cell line. Increasing the degree of resistance to mitoxantrone in the 8226 cell line from 10 to 37 times (8226/MR20) did not further reduce the intracellular drug concentration. However, the 8226/MR20 cell line exhibited 88 and 70% reductions in topoisomerase II beta and alpha expression, respectively, compared with the parental drug sensitive cell line. This decrease in topoisomerase expression and activity was not observed in the low-level drug-resistant, 8226/MR4 cell line. These data demonstrate that low-level mitoxantrone resistance is due to the presence of a novel, energy-dependent drug efflux pump similar to P-glycoprotein and multidrug resistance-associated protein. Reversal of resistance by blocking drug efflux with fumitremorgin C should allow for functional analysis of this novel transporter in cancer cell lines or clinical tumor samples. Increased resistance to mitoxantrone may result from reduced intracellular drug accumulation, altered nuclear/cytoplasmic drug distribution, and alterations in topoisomerase II activity.