title: A novel calmodulin antagonist O-(4-ethoxyl-butyl)-berbamine overcomes multidrug resistance in drug-resistant MCF-7/ADR breast carcinoma cells.
abstract: Multidrug resistance (MDR) mediated by the overexpression of the drug efflux protein P-glycoprotein is one of the major obstacles to successful cancer chemotherapy. The development of safe and effective MDR-reversing agents is an important approach to addressing this problem clinically. In this study, we evaluated the P-gp-modulatory potential of O-(4-ethoxyl-butyl)-berbamine (EBB), a novel calmodulin antagonist and derivative of bisbenzylisoquinoline alkaloid, which significantly improved the chemosensitivity of P-glycoprotein-mediated multidrug-resistant cells to doxorubicin compared with the efficacy of a conventional P-glycoprotein inhibitor, verapamil. EBB not only blocked the function of P-glycoprotein confirmed by the fact that EBB increased intracellular accumulation of rhodamine 123 and doxorubicin but also inhibited the expression of P-glycoprotein actualized by downregulating P-glycoprotein. Furthermore, our results showed that cotreatment with EBB and doxorubicin resulted in marked G(2)/M arrest and apoptosis of MCF-7/ADR cells, accompanied by down-regulation of the proteins cdc2/p34 and cyclin B1 and increased the levels of calcium ions. Taken together, these results suggest that cotreatment with EBB and doxorubicin could strongly potentiate the antitumor activity of doxorubicin, thus may have significant clinical application in cancer chemotherapy.
authors.affiliation: State Key Laboratory of Experimental Hematology, Institute of Hematology & Hospital of Blood Disease, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Liu
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Chen
authors.forename: Jing
authors.initials: J
authors.lastname: Qi
authors.forename: Simei
authors.initials: S
authors.lastname: Ren
authors.forename: Ming Yang
authors.initials: MY
authors.lastname: Xushi
authors.forename: Chunzheng
authors.initials: C
authors.lastname: Yang
authors.forename: Huifang
authors.initials: H
authors.lastname: Zhu
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Xiong
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D044182:Benzylisoquinolines / Q000737:chemistry / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy*; D016203:CDC2 Protein Kinase; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000037:antagonists & inhibitors*; D002277:Carcinoma / Q000188:drug therapy*; D045744:Cell Line, Tumor; D019926:Cyclin B / Q000378:metabolism; D056744:Cyclin B1 / Q000378:metabolism; D051358:Cyclin-Dependent Kinase 4 / Q000378:metabolism; D018844:Cyclin-Dependent Kinases; D004317:Doxorubicin / Q000494:pharmacology*; D018432:Drug Resistance, Multiple / Q000187:drug effects*; D005260:Female; D006801:Humans; D020112:Rhodamine 123 / Q000378:metabolism
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D044182:Benzylisoquinolines; D002147:Calmodulin; D019926:Cyclin B; D056744:Cyclin B1; D020112:Rhodamine 123; D004317:Doxorubicin; D016203:CDC2 Protein Kinase; C528899:CDK1 protein, human; C495900:CDK4 protein, human; D051358:Cyclin-Dependent Kinase 4; D018844:Cyclin-Dependent Kinases; D002118:Calcium; C027870:berbamine