title: 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.
abstract: This study investigated the reversal effect of isotetrandrine, an isoquinoline alkaloid extracted from Caulis mahoniae, on P-glycoprotein-mediated multidrug 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-dimethyhthiazol)-2,5 -diphenyltetrazolium 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 rhodamine 123 (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 microg x 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.
authors: Institute of Pharmacy, Henan University, Kaifeng 475004, China. wtx1975@henu.edu.cn
authors: Tian-Xiao
authors: TX
authors: Wang
authors: Xiao-Hong
authors: XH
authors: Yang
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000972:Antineoplastic Agents, Phytogenic / Q000302:isolation & purification / Q000494:pharmacology; D044182:Benzylisoquinolines / Q000302:isolation & purification / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000473:pathology; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple / Q000187:drug effects*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004365:Drugs, Chinese Herbal / Q000302:isolation & purification / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D019450:Genes, MDR; D006801:Humans; D028143:Mahonia / Q000737:chemistry; D018547:Plant Stems / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry; D020112:Rhodamine 123 / Q000378:metabolism
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000972:Antineoplastic Agents, Phytogenic; D044182:Benzylisoquinolines; D004365:Drugs, Chinese Herbal; D020112:Rhodamine 123; C009438:tetrandrine; D004317:Doxorubicin