Takara Kohji, Sakaeda Toshiyuki, Kakumoto Mikio, Tanigawara Yusuke, Kobayashi Hironao, Okumura Katsuhiko, Ohnishi Noriaki, Yokoyama Teruyoshi
Frontier Education Center, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan.
Oncol Res. 2009;17(11-12):527-33. doi: 10.3727/096504009789745601.
The purpose of this study is to examine the effects of doxazosin, an alpha-adrenoceptor antagonist, on P-glycoprotein/MDR1-mediated multidrug resistance (MDR) and the transport of anticancer drugs. The effects of doxazosin, prazosin, and terazosin on MDR1-mediated MDR were assessed in human cervical carcinoma HeLa cells and the MDR1-overexpressing derivative Hvrl00-6, established by stepwise increases of the vinblastine concentration in the culture medium. The effects of doxazosin on the transcellular transport and intracellular accumulation of [3H]vinblastine, [3H]daunorubicin, and [3H]digoxin, all MDR1 substrates, were evaluated using LLC-GA5-COL150 cell monolayers, established by transfection of human MDR1 cDNA into porcine kidney epithelial LLC-PK1 cells. The sensitivity to vinblastine and paclitaxel of Hvrl00-6 cells was increased at 3.4- and 17.5-fold, respectively, by the addition of 1 microM doxazosin, whereas prazosin and terazosin had weaker or no such effects. Prazosin at 1 microM had a reversal effect on the sensitivity to vinblastine, whereas terazosin had no effect. In transport experiments, doxazosin concentration dependently increased the apical-to-basal transport of radiolabeled drugs in LLC-GA5-COL150 cells, but did not show remarkable effects on the basal-to-apical transport. In addition, doxazosin restored the intracellular accumulation in a concentration-dependent manner in LLC-GA5-COL150 cells. Doxazosin may partly reverse MDR by inhibiting MDR1-mediated transport, making it a candidate lead compound in the development of a reversing agent for MDR.
本研究的目的是考察α-肾上腺素受体拮抗剂多沙唑嗪对P-糖蛋白/MDR1介导的多药耐药性（MDR）及抗癌药物转运的影响。通过逐步提高培养基中长春碱的浓度，在人宫颈癌HeLa细胞及过表达MDR1的衍生细胞Hvrl00-6中评估多沙唑嗪、哌唑嗪和特拉唑嗪对MDR1介导的MDR的作用。利用将人MDR1 cDNA转染至猪肾上皮LLC-PK1细胞而建立的LLC-GA5-COL150细胞单层，评估多沙唑嗪对所有MDR1底物[3H]长春碱、[3H]柔红霉素和[3H]地高辛的跨细胞转运及细胞内蓄积的影响。添加1μM多沙唑嗪后，Hvrl00-6细胞对长春碱和紫杉醇的敏感性分别提高了3.4倍和17.5倍，而哌唑嗪和特拉唑嗪的作用较弱或无此作用。1μM哌唑嗪对长春碱敏感性有逆转作用，而特拉唑嗪无此作用。在转运实验中，多沙唑嗪浓度依赖性地增加了LLC-GA5-COL150细胞中放射性标记药物的从顶向基底转运，但对从基底向顶的转运无显著影响。此外，多沙唑嗪在LLC-GA5-COL150细胞中以浓度依赖性方式恢复了细胞内蓄积。多沙唑嗪可能通过抑制MDR1介导的转运而部分逆转MDR，使其成为MDR逆转剂开发中的候选先导化合物。
