title: [Effects of miRNA-21 on paclitaxel-resistance in human breast cancer cells].
abstract: To investigate the effects of miR-21 on paclitaxel-resistance in human breast cancer MCF-7/PR and SKBR-3/PR cells.
  
  
  
  Paclitaxel-resistant human breast cancer cell lines MCF-7/PR and SKBR-3/PR were established by stepwise selection in increasing concentration of paclitaxel. Cellular morphology, mRNA and protein level of MDR1, BCRP and MRP1 in MCF-7/PR and SKBR-3/PR cells were determined. The expression of Bax, Bcl-2 and miR-21 in parental and paclitaxel-resistant cells was detected by RT-PCR and Western blotting. The synthetic miR-21 inhibitor or miR-21 mimic were transfected into MCF-7/PR, SKBR-3/PR and MCF-7, SKBR-3 cells with Lipofectamine 2000. The miR-21 levels were determined by RT-PCR, and P-gp, Bcl-2 and Bax protein levels were examined by Western blotting. MTT assay was used to measure the cell viability, and flow cytometry was performed to analyze the cell cycle and apoptosis.
  
  
  
  The levels of MDR1, BCRP, MRP1, Bcl-2/Bax and miR-21 in MCF-7/PR and SKBR-3/PR cells were significantly higher than those in MCF-7 and SKBR-3 cells. The protein levels of P-gp, Bcl-2 were up-regulated, and Bax was down-regulated compared with parental cells. MiR-21 was significantly down-regulated after miR-21 inhibitor was transfected; and the levels of MDR1, BCRP, MRP1 and Bcl-2/Bax (P <0.05) were also down-regulated. MiR-21 inhibitors significantly suppressed G0/G1 transition of the cell cycle, and induced cell apoptosis in MCF-7/PR and SKBR-3/PR cells. MTT results showed that miR-21 inhibitors induced sensitivity of MCF-7/PR and SKBR-3/PR cells to paclitaxel. And miR-21 mimic can increase the expression of MDR1, Bcl-2/Bax and change cell morphology from parental cells to resistant cells.
  
  
  
  The established MCF-7/PR and SKBR-3/PR breast cancer cells show typical multidrug resistance characteristics, which can be used as the model for drug resistance study. Down-regulated miR-21 expression in MCF-7/PR and SKBR-3/PR breast cancer cells can enhance cell sensitivity to paclitaxel.
authors.affiliation: Clinical Diagnosis Center, Bengbu Medical College, Bengbu 233000, China.
authors.forename: Zun-lan
authors.initials: ZL
authors.lastname: Zhao
authors.affiliation: Clinical Diagnosis Center, Bengbu Medical College, Bengbu 233000, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Cai
authors.affiliation: Clinical Diagnosis Center, Bengbu Medical College, Bengbu 233000, China.
authors.forename: Yang-yang
authors.initials: YY
authors.lastname: Wang
authors.affiliation: Department of Bioscience, Bengbu Medical College, Bengbu 233000, China.
authors.forename: Chun-lei
authors.initials: CL
authors.lastname: Xia
authors.affiliation: Department of Bioscience, Bengbu Medical College, Bengbu 233000, China.
authors.forename: Cong-xin
authors.initials: CX
authors.lastname: Li
authors.affiliation: Department of Biochemistry · Molecular Biology, Bengbu Medical College, Bengbu 233000, China.
authors.forename: Su-lian
authors.initials: SL
authors.lastname: Chen
authors.affiliation: Department of Biochemistry · Molecular Biology, Bengbu Medical College, Bengbu 233000, China.
authors.forename: Qing-ling
authors.initials: QL
authors.lastname: Yang
authors.affiliation: Department of Biochemistry · Molecular Biology, Bengbu Medical College, Bengbu 233000, China.
authors.forename: Chang-jie
authors.initials: CJ
authors.lastname: Chen
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000378:metabolism; D017209:Apoptosis; D001943:Breast Neoplasms / Q000378:metabolism*; D045744:Cell Line, Tumor; D015536:Down-Regulation; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D035683:MicroRNAs / Q000378:metabolism*; D017239:Paclitaxel / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012333:RNA, Messenger; D015854:Up-Regulation; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; C494826:BAX protein, human; C000595707:BCL2 protein, human; C524940:MIRN21 microRNA, human; D035683:MicroRNAs; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D051028:bcl-2-Associated X Protein; D017239:Paclitaxel