title: MicroRNA-133b targets glutathione S-transferase π expression to increase ovarian cancer cell sensitivity to chemotherapy drugs.
abstract: BACKGROUND
  Accumulating studies reveal that aberrant microRNA (miRNA) expression can affect the development of chemotherapy drug resistance by modulating the expression of relevant target proteins. The aim of this study was to investigate the role of miR-133b in the development of drug resistance in ovarian cancer cells.
  
  
  METHODS
  We examined the levels of miR-133b expression in ovarian carcinoma tissues and the human ovarian carcinoma cell lines (A2780, A2780/DDP and A2780/Taxol, respectively). We determined the cell viability of these cell lines treated with cisplatin or paclitaxel in the presence or absence of miR-133b or anti-miR-133b transfection using the MTT assay. Reverse transcription polymerase chain reaction and Western blotting were used to assess the mRNA and protein expression levels of two drug-resistance-related genes: glutathione S-transferase (GST)-π and multidrug resistance protein 1 (MDR1). The dual-luciferase reporter assay was used to detect the promoter activity of GST-π in the presence and absence of miR-133b.
  
  
  RESULTS
  The expression of miR-133b was significantly lower in primary resistant ovarian carcinomas than in the chemotherapy-sensitive carcinomas (P<0.05), and the same results were found in primary resistant ovarian cell lines (A2780/Taxol and A2780/DDP) compared to the chemotherapy-sensitive cell line (A2780; P<0.05). Following miR-133b transfection, four cell lines showed increased sensitivity to paclitaxel and cisplatin, while anti-miR-133b transfection reduced cell sensitivity to paclitaxel and cisplatin. Dual-luciferase reporter assay showed that miR-133b interacted with the 3'-untranslated region of GST-π. Compared to controls, the mRNA and protein levels of MDR1 and GST-π were downregulated after miR-133b transfection and upregulated after anti-miR-133b transfection.
  
  
  CONCLUSIONS
  MicroRNA-133b may reduce ovarian cancer drug resistance by silencing the expression of the drug-resistance-related proteins, GST-π and MDR1. In future, the combination of miR-133b with chemotherapy agents may prevent the development of drug resistance in ovarian cancers.
authors.affiliation: Department of Gynecology, The First Affiliated Hospital of China Medical University, Shenyang, People's Republic of China.
authors.forename: Shuo
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Gynecology, The Affiliated Hospital of Medical College, Qingdao University, Qingdao, People's Republic of China.
authors.forename: Jin-Wen
authors.initials: JW
authors.lastname: Jiao
authors.affiliation: Department of Gynecology, The First Affiliated Hospital of China Medical University, Shenyang, People's Republic of China.
authors.forename: Kai-Xuan
authors.initials: KX
authors.lastname: Sun
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Basic Medicine, China Medical University, Shenyang, People's Republic of China.
authors.forename: Zhi-Hong
authors.initials: ZH
authors.lastname: Zong
authors.affiliation: Department of Gynecology, The First Affiliated Hospital of China Medical University, Shenyang, People's Republic of China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D020413:3' Untranslated Regions; D018435:ATP Binding Cassette Transporter, Subfamily B / Q000235:genetics / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001665:Binding Sites; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology*; D018284:Cystadenocarcinoma, Serous / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D051549:Glutathione S-Transferase pi / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D017239:Paclitaxel / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014162:Transfection
chemical_list: D020413:3' Untranslated Regions; C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D000970:Antineoplastic Agents; C548234:MIRN133 microRNA, human; D035683:MicroRNAs; C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi; D017239:Paclitaxel; D002945:Cisplatin
keywords: cisplatin; drug resistance; ovarian cancer cells; paclitaxel