title: miR-302a/b/c/d cooperatively inhibit BCRP expression to increase drug sensitivity in breast cancer cells.
abstract: BCRP is overexpressed in many tumors and mediates multidrug resistance in breast cancer. In this study, we determined the involvement of miR-302S in the development of drug resistance in breast cancer.
  
  
  
  The differential miRNA expression profiling in parental MCF-7 cells and its derivative mitoxantrone (MX)-resistant MCF-7 (MCF-7/MX) cells was determined by the microarray analysis. The levels of miR-302S family and BCRP mRNA expression were determined by using Quantitative Real-Time PCR. The targeting effect between the individuals of miR-302S and BCRP mRNA-3'UTR were detected by dual-luciferase reporter assay. Proteins of BCRP are represented by Western blot assay. Cell viability was assessed by MTS assay. Efflux capacity was evaluated using flow cytometry.
  
  
  
  The miR-302S family including miR-302a, miR-302b, miR-302c, and miR-302d was significantly down-regulated in BCRP-overexpressing MCF-7/MX cells. Luciferase activity assay showed that miR-302 inhibited BCRP expression by targeting the 3'-untranslated region (UTR) of the BCRP mRNA. Overexpression of miR-302 increased intracellular accumulation of MX and sensitized breast cancer cells to MX. Furthermore, intratumoral injection of miR-302 potentiated the inhibitory effect of MX on tumor growth in mice transplanted with MCF-7/MX cells. Most importantly, miR-302S produced stronger effects than each individual member alone.
  
  
  
  These findings suggest that miR-302 inhibits BCRP expression via targeting the 3'-UTR of BCRP mRNA. miR-302 members may cooperatively downregulate BCRP expression to increase chemosensitivity of breast cancer cells. miR-302 gene cluster may be a potential target for reversing BCRP-mediated chemoresistance in breast cancer.
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Puhe Road 77, Shenyang North New Area, Shenyang, 110122, Liaoning Providence, PR China. Electronic address: cmuwy@126.com.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Puhe Road 77, Shenyang North New Area, Shenyang, 110122, Liaoning Providence, PR China. Electronic address: zl_cmu@163.com.
authors.forename: Lin
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Puhe Road 77, Shenyang North New Area, Shenyang, 110122, Liaoning Providence, PR China. Electronic address: qinghuanxiao12345@163.com.
authors.forename: Qinghuan
authors.initials: Q
authors.lastname: Xiao
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Puhe Road 77, Shenyang North New Area, Shenyang, 110122, Liaoning Providence, PR China. Electronic address: jianglongyang1987@126.com.
authors.forename: Longyang
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Puhe Road 77, Shenyang North New Area, Shenyang, 110122, Liaoning Providence, PR China. Electronic address: hemiao_cmu@126.com.
authors.forename: Miao
authors.initials: M
authors.lastname: He
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Puhe Road 77, Shenyang North New Area, Shenyang, 110122, Liaoning Providence, PR China. Electronic address: fengfengfriend@163.com.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Bai
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Puhe Road 77, Shenyang North New Area, Shenyang, 110122, Liaoning Providence, PR China. Electronic address: mmttanxiao@163.com.
authors.forename: Mengtao
authors.initials: M
authors.lastname: Ma
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Puhe Road 77, Shenyang North New Area, Shenyang, 110122, Liaoning Providence, PR China. Electronic address: jiaoxy2012@163.com.
authors.forename: Xuyang
authors.initials: X
authors.lastname: Jiao
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Puhe Road 77, Shenyang North New Area, Shenyang, 110122, Liaoning Providence, PR China. Electronic address: weiminjiecmu@163.com.
authors.forename: Minjie
authors.initials: M
authors.lastname: Wei
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2 / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D001483:Base Sequence; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm; D005260:Female; D064593:Heterografts; D006801:Humans; D061986:MCF-7 Cells; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008942:Mitoxantrone / Q000494:pharmacology; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D014162:Transfection
chemical_list: C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D000970:Antineoplastic Agents; C532169:MIRN302A microRNA, human; D035683:MicroRNAs; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D008942:Mitoxantrone
keywords: BCRP; Breast cancer; Drug resistance; MiR-302