功劳木中异汉防己碱对P-糖蛋白介导的人乳腺癌细胞多药耐药性的逆转作用(英文)

Reversal effect of isotetrandrine,an isoquinoline alkaloid extracted from Caulis Mahoniae,on P-glycoprotein-mediated doxorubicin-resistance in human breast cancer(MCF-7/DOX) cells

本文探讨了异汉防己碱对P-糖蛋白(P-gp)介导的人乳腺癌细胞多药耐药性的逆转作用。首先以RT-PCR和免疫组化方法分别从RNA和蛋白水平检测MCF-7/DOX细胞P-gp表达情况,以明确MCF-7/DOX细胞的耐药特征;然后采用MTT法检测异汉防己碱的内在细胞毒性及其对阿霉素(DOX)的增敏作用,并以RF(reversal fold)值评价其逆转效果;同时应用流式细胞仪(FCM)对细胞内DOX的蓄积量进行了分析;再以免疫组化方法检测异汉防己碱对MCF-7/DOX细胞P-gp表达水平的影响;最后采用罗丹明蓄积和外排试验检测了异汉防己碱对P-gp功能的影响。整个试验以维拉帕米作为阳性对照。实验结果表明:MCF-7/DOX细胞是具有多药耐药表型且P-gp表达阳性的细胞株;无毒剂量异汉防己碱可明显增强DOX对MCF-7/DOX细胞的细胞毒性(RF=3.89),明显高于维拉帕米(RF=2.54)的逆转活性(P<0.05),但其几乎不影响DOX对MCF-7细胞的抑制作用;异汉防己碱对MCF-7/DOX细胞P-gp表达水平无明显影响,但其可有效抑制P-gp的药物外排功能。因此,异汉防己碱可有效逆转P-gp介导的人乳腺癌细胞的多药耐药性,它可能成为有效多药耐药逆转剂的候选药物。

This study investigated the reversal effect of isotetrandrine, an isoquinoline alkaloid extracted from Caulis mahoniae, on P-glycoprotein-mediated muhidrug resistance in human breast cancer doxorubicin-resistant （MCF-7/DOX） cells. RT-PCR assay and immunity histochemistry assay were used to determine the expression level of mdrl gene and P-gp in MCF-7/DOX cells to elucidate resistant character of MCF-7/DOX cells. The activity of isotetrandine to enhance doxorubicin cytotoxicity was tested using MTT （3-（4,5-dimethylthiazol）-2,5-diphenyhetrazolium bromide） assay and was evaluated by the reversal fold （RF） values. Intracellular accumulation of doxorubicin was assessed by the determination of doxorubicin-associated fluorescence intensity. Effect of isotetrandrine on the expression level of P-gp in MCF-7/DOX cells was then determined by immunity histochemistry assay. The ability of isotetrandrine to inhibit P-gp function was evaluated by detecting the accumulation and efflux of rhodamine123 （Rh123） with flow cytometry （FCM）. Verapamil was employed as a comparative agent in whole experiment. The results indicated that MCF-7/DOX cells had phenotype of MDR and that the positive expression of P-gp was their resistant character. 10 μg · mL^-1 isotetrandrine could distinctly enhance cytotoxicity of DOX in MCF-7/DOX cells and reversal fold （RF） was significantly higher than that of verapamil （P 〈0. 05）, but it hardly affected cytotoxicity of DOX in MCF-7 cells and the expression level of P-gp in MCF-7/DOX cells. The ability of isotetrandrine to inhibit P-gp function was reversible, because incubation of MCF-7/ DOX cells with isotetrandrine caused a marked increase in uptake and a notable decrease in efflux of Rh123 and a marked increase of intracellular DOX concentrations. In conclusion, isotetrandrine exhibited potent effect on the reversal of P-gp-mediated MDR in vitro, suggesting that it might become a candidate of effective MDR reversing agent in cancer chemotherapy.