【摘要】 目的:研究白血病细胞多药耐药发生的机制. 方法:用逐步增加培养基中阿霉素（Dox）浓度的方法,诱导出一株耐Dox的人白血病细胞系K562/A02.用[³H]TdR参入法测定IC₅₀,HPLC法测定细胞内药物浓度,免疫组织化学法检测P-糖蛋白的表达,RT-PCR法测定mdr1基因表达,点杂交测定基因组中mdr1DNA和拓扑异构酶Ⅱ（TopⅡ）基因表达,CDNB法测定谷胱甘肽-S-转移酶（GST）活性. 结果:K562/A02对Dox、HHT、Dau、VCR、m-AMSA、VP-16具有较强的交叉耐药性,而对Ara-C耐药较弱,对5-FU、Cis和MTX不交叉耐药,表现出典型的多药耐药表型.K562/A02细胞内药物浓度明显低于K562细胞,P-170阳性表达.K562/A02细胞中MDR1基因拷贝数与K562的无差异,但mdr1mRNA高表达.TopⅡ的mRNA水平低于K562,GST的活性增高. 结论:白血病细胞多药耐药的机制与mdr1基因表达密切相关,也与TopⅡ和GST有关.更多还原

【Abstract】 To study the mechanism of the development of multidrug resistance in leukemic cells. METHODS: A human leukemic cell line K562/A02 was established by stepwise increase of concentrations of doxorubicin (Dox) in medium. P-glycoprotein was detected by immunohistochemistry assay. The mdrl gene expression was measured by RT-PCR. The amplification of mdrl gene in its genome, and DNA topisomerase Ⅱ (Top Ⅱ ) gene expression were determined by dot-blot hybridization. RESULTS: K562/A02 was highly cross-resistant to vincristine (VCR), homo-harringtonin (HHT), amsacrine (m-AMSA), daunorubicin (Dau) and etoposide (VP-16), slightly to cytosine arabinoside (Ara-C), but not cisplatin (Cis), methotrexate (MTX) and fluorouracil (5-FU) , showing a typical pheno-type of MDR. Intracellular accumulation of Dau in K562/A02 was 33 % as high as that in K562. P-glycoprotein P-170 was positive. In K562/A02, the mdrl gene did not amplify, the mdrl mRNA level was markedly higher, the Top Ⅱ mRNA level was lower, and glu-tathione-5-transferase (GST) activity was higher than in K562. CONCLUSION: mdrl mRNA was overexpression and thus the encoded P-170 was responsible for MDR in K562/A02 while Top Ⅱ or GST may play a role in MDR.更多还原