Kohno K, Sato S, Uchiumi T, Takano H, Tanimura H, Miyazaki M, Matsuo K, Hidaka K, Kuwano M
Int J Oncol. 1992 Jun;1(1):73-7. doi: 10.3892/ijo.1.1.73.
The multidrug resistance (MDR1) gene encodes a Mr 170,000 energy-dependent membrane efflux pump termed P-glycoprotein, and the P-glycoprotein is often expressed in various human tumors before and after cancer chemotherapy. In this study, we have established a human cancer KB cell line (Kst-6) which stably expressed the CAT gene (pMDRCAT1) driven by the human MDR1 promoter. Exposure to inhibitors of DNA topoisomerase I (camptothecin: CPT-11) and II (etoposide: VP-16 and teniposide: VM-26) could efficiently induce CAT activities in both time- and dose-dependent manners. However, CAT activity could not be significantly induced when treated with an ATP-antagoist, novobiocin. Northern blot analysis showed about 5-fold increase in CAT mRNA levels in Kst-6 cells treated with CPT-11 or VP-16, but not with novobiocin. Proximal MDR1 promoter-binding activities of transacting factor were augmented in nuclear extracts from KB cells treated with CPT-11, VM-26, and VP-16.
多药耐药（MDR1）基因编码一种分子量为170,000的能量依赖性膜转运泵，称为P-糖蛋白，且P-糖蛋白常在癌症化疗前后的各种人类肿瘤中表达。在本研究中，我们建立了一种人癌细胞KB细胞系（Kst-6），该细胞系稳定表达由人MDR1启动子驱动的CAT基因（pMDRCAT1）。暴露于DNA拓扑异构酶I抑制剂（喜树碱：CPT-11）和II抑制剂（依托泊苷：VP-16和替尼泊苷：VM-26）能够以时间和剂量依赖性方式有效诱导CAT活性。然而，用ATP拮抗剂新生霉素处理时，CAT活性未被显著诱导。Northern印迹分析显示，用CPT-11或VP-16处理的Kst-6细胞中CAT mRNA水平增加约5倍，但用新生霉素处理则无此现象。在用CPT-11、VM-26和VP-16处理的KB细胞核提取物中，反式作用因子与MDR1启动子近端的结合活性增强。
