title: An in vitro model for the development of acquired tamoxifen resistance.
abstract: The development of resistance to tamoxifen (Tam) remains a challenging clinical problem for ER+ breast cancer patients. To understand the mechanisms underlying of resistance, previous studies have driven the acquisition of Tam resistance by exposing cells to varying concentration of drug for varying lengths of time. However, a detailed protocol for the establishment of Tam-resistant cells remains to be clarified. In the present study, we aimed to determine and compare the effect of different in vitro protocols on the degree of resistance to 4-hydroxytamoxifen (4-OH Tam) for MCF7 cells. For this purpose, MCF7-Tam resistance (MCF7-TamR) cells were developed by treated with different concentrations (100, 200, 400, 600, 800 and 1000 nM) of 4-OH Tam over 3 months. The relative resistance was measured by WST-1 analysis. Studies characterizing of the 4-OH Tam resistance of MCF7-TamR cells were performed by 17 β-oestradiol (E2) and Annexin V/PI analysis. In addition, the expression levels of ABCC1, ABCG2 and ABCG1 were detected by RT-PCR, any changes in morphological of each resistance group were observed at the end of each month and compared with parental MCF7 cells. Consequently, exposure time and concentration can affect the degree of resistance to 4-OH Tam; thus, dose and treatment duration should be chosen according to the desired degree of resistance. This work presents a novel procedure for the generation of MCF7-TamR cells, thus enabling the identification and characterization of MCF7-TamR cells.
authors: Department of Medical Biology, Faculty of Medicine, Uludag University, Bursa, 16059, Turkey.
authors: Gamze
authors: G
authors: Guney Eskiler
authors: Department of Medical Biology, Faculty of Medicine, Uludag University, Bursa, 16059, Turkey. gcecener@uludag.edu.tr.
authors: Gulsah
authors: G
authors: Cecener
authors: Department of Medical Biology, Faculty of Medicine, Uludag University, Bursa, 16059, Turkey.
authors: Berrin
authors: B
authors: Tunca
authors: Department of Medical Biology, Faculty of Medicine, Uludag University, Bursa, 16059, Turkey.
authors: Unal
authors: U
authors: Egeli
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000235:genetics / Q000378:metabolism; D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2 / Q000235:genetics / Q000378:metabolism; D000704:Analysis of Variance; D017209:Apoptosis / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004958:Estradiol / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D061986:MCF-7 Cells; D008954:Models, Biological; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013629:Tamoxifen / Q000494:pharmacology*
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D004958:Estradiol; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D012333:RNA, Messenger; D013629:Tamoxifen; C513055:ABCB1 protein, human; C073119:TAP1 protein, human; C421109:multidrug resistance-associated protein 1
keywords: Breast cancer; Drug resistance; MCF7 cells; Tamoxifen