Hara N
Third Department of Internal Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
Hokkaido Igaku Zasshi. 1995 Jul;70(4):573-89.
The development of drug resistance in cancer cells is a significant clinical problem for the successful cancer chemotherapy. Since the cytoskeleton, including microtubules, may be involved in modulating cellular signal transduction, morphological and structural changes, the microtubules assembly of multidrug resistant cells was examined using Confocal Laser Microscope MRC500 system (Bio Rad). In this study, multidrug resistant cells were established by the continuous exposure to ADR(adriamycin) starting with 20 nM up to 1 microM. The expression of MDR-1 (multidrug resistance) gene was detected in K562 leukemia cells and to more extent in the multidrug resistant K562/ADR cells, but not in HL-60 leukemia cells and multidrug resistant HL-60/ADR cells by RT-PCR method. The chronological features of microtubules assembly in the parent cell lines were lost on day 3, after incubation with 20nM of ADR. In accordance with development of drug resistance, the microtubules assembly appeared to be more dense and stronger than that of parent cells. During the development of drug resistant cells, the ADR-accumulation in the nucleus was decreased according to the increase of microtubules assembly. In the case of incubation with 0.5 microM colcemid, an inhibitor of microtubules polymerization, for 3 hours, the stainings of microtubules were lost their fine network and appeared to be diffuse and dot-like pattern. At the same time, both untreated HL-60/ADR and K562/ADR showed the decrease of ADR-accumulation, but the accumulations both colcemid treated resistant cells were increased the same level of their parent cells at the point of 120 min. These results suggested that the resistance to ADR in human leukemia cells correlated with microtubules assembly, and the microtubules assembly played an important role of drug resistance with or without MDR-1 gene overexpression.
癌细胞中耐药性的产生是癌症化疗成功面临的一个重大临床问题。由于细胞骨架，包括微管，可能参与调节细胞信号转导、形态和结构变化，因此使用共聚焦激光显微镜MRC500系统（伯乐公司）检测了多药耐药细胞的微管组装情况。在本研究中，通过从20 nM至1 microM持续暴露于阿霉素（ADR）来建立多药耐药细胞。通过RT-PCR方法在K562白血病细胞中检测到多药耐药（MDR-1）基因的表达，在多药耐药的K562/ADR细胞中表达程度更高，但在HL-60白血病细胞和多药耐药的HL-60/ADR细胞中未检测到。在与20 nM的ADR孵育3天后，亲代细胞系中微管组装的时间特征消失。随着耐药性的发展，微管组装似乎比亲代细胞更密集、更强。在耐药细胞的发展过程中，随着微管组装的增加，细胞核中ADR的积累减少。在用微管聚合抑制剂0.5 microM秋水仙酰胺孵育3小时的情况下，微管染色失去了精细网络，呈现出弥散和点状模式。同时，未经处理的HL-60/ADR和K562/ADR均显示ADR积累减少，但在120分钟时，秋水仙酰胺处理的耐药细胞的积累增加到与亲代细胞相同的水平。这些结果表明，人类白血病细胞对ADR的耐药性与微管组装相关，并且微管组装在有或没有MDR-1基因过表达的情况下对耐药性都起着重要作用。
