Diddens H, Gekeler V, Neumann M, Niethammer D
Medizinisch-Naturwissenschaftliches Forschungzentrum, Universität Tübingen, FRG.
Int J Cancer. 1987 Nov 15;40(5):635-42. doi: 10.1002/ijc.2910400511.
Actinomycin D (DACT)-resistant sublines of the Chinese hamster ovary cell line CHO-K1 were selected in vitro. Sublines were derived which expressed 5.2-fold (CHO 15DACT) and 35.8-fold (CHO 100DACT) resistance to DACT. The CHO 100DACT subline displayed marked cross-resistance to bleomycin, adriamycin, daunomycin, vinblastine, vincristine, VP 16 and VM 26. No cross-resistance was found to cisplatin or methotrexate. The resistant cells exhibited enhanced (collateral) sensitivity to prednisolone. Combination of prednisolone with vincristine resulted in a pronounced synergistic effect on sensitive cells, whereas in resistant cells the combined effect of both drugs was merely additive. Resistant cells, viably stained with the DNA-specific dye Hoechst 33342, exhibited decreased fluorescence intensities compared to parental cells. In contrast to sensitive cells the resistant sublines did not accumulate the mitochondria-specific dye rhodamine 123. Co-incubation with verapamil, however, effectively enhanced accumulation of the dye. The potential diagnostic value of these fluorescent compounds as marker dyes for the multidrug-resistance phenotype is discussed. Non-toxic doses of verapamil almost completely reversed the resistance to various drugs in CHO 100DACT cells. Specific DNA sequences were amplified in resistant cells, and the increase in resistance was paralleled by a concomitant increase in the copy number of these sequences, suggesting that the corresponding gene may be functionally linked to the multidrug-resistance phenotype.
在体外筛选出了中国仓鼠卵巢细胞系CHO-K1对放线菌素D（DACT）耐药的亚系。获得了对DACT具有5.2倍（CHO 15DACT）和35.8倍（CHO 100DACT）耐药性的亚系。CHO 100DACT亚系对博来霉素、阿霉素、柔红霉素、长春碱、长春新碱、VP 16和VM 26表现出明显的交叉耐药性。对顺铂或甲氨蝶呤未发现交叉耐药性。耐药细胞对泼尼松龙表现出增强的（间接）敏感性。泼尼松龙与长春新碱联合使用对敏感细胞产生显著的协同作用，而在耐药细胞中，两种药物的联合作用仅为相加作用。用DNA特异性染料Hoechst 33342进行活细胞染色时，与亲代细胞相比，耐药细胞的荧光强度降低。与敏感细胞不同，耐药亚系不积累线粒体特异性染料罗丹明123。然而，与维拉帕米共同孵育可有效增强染料的积累。讨论了这些荧光化合物作为多药耐药表型标记染料的潜在诊断价值。无毒剂量的维拉帕米几乎完全逆转了CHO 100DACT细胞对各种药物的耐药性。在耐药细胞中扩增了特定的DNA序列，耐药性的增加与这些序列拷贝数的相应增加平行，表明相应基因可能在功能上与多药耐药表型相关。
