Hu X F, Slater A, Rischin D, Kantharidis P, Parkin J D, Zalcberg J
Trescowthick Laboratory, Peter MacCallum Cancer Institute, Melbourne, Australia.
Br J Cancer. 1999 Feb;79(5-6):831-7. doi: 10.1038/sj.bjc.6690133.
The effects of 4-demethoxydaunorubicin (idarubicin, IDA) and MX2, a new morpholino-anthracycline, on up-regulation of the MDR1 gene in the low-level multidrug resistant (MDR) cell line CEM/A7R were compared at similar concentrations (IC10, IC50 and IC90) over a short time exposure (4 and 24 h). The chemosensitivity of each drug was determined by a 3-day cell growth inhibition assay. Compared with epirubicin (EPI), IDA and MX2 were 17- and eightfold more effective in the CEM/A7R line respectively. No cross-resistance to 5-FU was seen in the CEM/A7R line. Verapamil (5 microM) and PSC 833 (1 microM), which dramatically reversed resistance to EPI in the CEM/A7R line, had no sensitizing effect on the resistance of this line to MX2, but slightly decreased resistance to IDA. The sensitivity to 5-FU was unchanged by these modulators. The induction of MDR1 mRNA expression by IDA, MX2 and 5-FU was analysed by Northern blotting and semiquantitatively assessed by scanning Northern blots on a phosphorimager. The relative level of MDR1 expression was expressed as a ratio of MDR1 mRNA to the internal RNA control glyceraldehyde-3-phosphate dehydrogenase (GAPDH). IDA, MX2 and 5-FU differentially up-regulated MDR1 mRNA in the CEM/A7R line in a dose-dependent manner. Both IDA and MX2 induced MDR1 expression within 4 h. 5-FU up-regulated MDR1 expression only when drug exposure was prolonged to 24 h. Based on MRK 16 binding, flow cytometric analysis of P-glycoprotein (Pgp) expression paralleled the increase in MDR1 mRNA levels. For the three anthracyclines, the increase in MDR1 expression was stable in cells grown in the absence of drug for more than 3 weeks after drug treatment. The induction of MDR1 expression by 5-FU was transient, associated with a rapid decrease in the increased Pgp levels which returned to baseline 72 h after the removal of 5-FU. This study demonstrates that MDR1 expression can be induced by analogues of anthracyclines not pumped by Pgp, and that this induction appears to be stable despite a 3-week drug-free period.
比较了4-去甲氧基柔红霉素（伊达比星，IDA）和一种新型吗啉代蒽环类药物MX2在相似浓度（IC10、IC50和IC90）下短时间暴露（4小时和24小时）对低水平多药耐药（MDR）细胞系CEM/A7R中MDR1基因上调的影响。每种药物的化学敏感性通过为期3天的细胞生长抑制试验来确定。与表柔比星（EPI）相比，IDA和MX2在CEM/A7R细胞系中的效力分别高17倍和8倍。在CEM/A7R细胞系中未观察到对5-氟尿嘧啶（5-FU）的交叉耐药。维拉帕米（5微摩尔）和PSC 833（1微摩尔）可显著逆转CEM/A7R细胞系对EPI的耐药性，但对该细胞系对MX2的耐药性无增敏作用，不过对IDA的耐药性有轻微降低。这些调节剂对5-FU的敏感性无影响。通过Northern印迹法分析IDA、MX2和5-FU对MDR1 mRNA表达的诱导作用，并通过磷光成像仪扫描Northern印迹进行半定量评估。MDR1表达的相对水平以MDR1 mRNA与内部RNA对照甘油醛-3-磷酸脱氢酶（GAPDH）的比值表示。IDA、MX2和5-FU在CEM/A7R细胞系中以剂量依赖性方式差异性地上调MDR1 mRNA。IDA和MX2在4小时内均可诱导MDR1表达。仅当药物暴露延长至24小时时，5-FU才会上调MDR1表达。基于MRK 16结合，对P-糖蛋白（Pgp）表达的流式细胞术分析与MDR1 mRNA水平的增加平行。对于这三种蒽环类药物，在药物处理后，在无药物培养超过3周的细胞中，MDR1表达的增加是稳定的。5-FU对MDR1表达的诱导是短暂的，与Pgp水平升高后的快速下降相关，在去除5-FU后72小时恢复至基线水平。本研究表明，MDR1表达可由非Pgp转运的蒽环类药物类似物诱导，并且尽管有3周的无药期，这种诱导似乎是稳定的。
