title: miR-634 restores drug sensitivity in resistant ovarian cancer cells by targeting the Ras-MAPK pathway.
abstract: BACKGROUND
  Drug resistance hampers the efficient treatment of malignancies, including advanced stage ovarian cancer, which has a 5-year survival rate of only 30 %. The molecular processes underlying resistance have been extensively studied, however, not much is known about the involvement of microRNAs.
  
  
  METHODS
  Differentially expressed microRNAs between cisplatin sensitive and resistant cancer cell line pairs were determined using microarrays. Mimics were used to study the role of microRNAs in drug sensitivity of ovarian cancer cell lines and patient derived tumor cells. Luciferase reporter constructs were used to establish regulation of target genes by microRNAs.
  
  
  RESULTS
  MiR-634 downregulation was associated with cisplatin resistance. Overexpression of miR-634 affected cell cycle progression and enhanced apoptosis in ovarian cancer cells. miR-634 resensitized resistant ovarian cancer cell lines and patient derived drug resistant tumor cells to cisplatin. Similarly, miR-634 enhanced the response to carboplatin and doxorubicin, but not to paclitaxel. The cell cycle regulator CCND1, and Ras-MAPK pathway components GRB2, ERK2 and RSK2 were directly repressed by miR-634 overexpression. Repression of the Ras-MAPK pathway using a MEK inhibitor phenocopied the miR-634 effects on viability and chemosensitivity.
  
  
  CONCLUSIONS
  miR-634 levels determine chemosensitivity in ovarian cancer cells. We identify miR-634 as a therapeutic candidate to resensitize chemotherapy resistant ovarian tumors.
authors.affiliation: Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center Rotterdam, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands.|Present address: Max Planck Institute for Molecular Genetics, Berlin, Germany.
authors.forename: Marijn T M
authors.initials: MT
authors.lastname: van Jaarsveld
authors.affiliation: Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center Rotterdam, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands.
authors.forename: Patricia F
authors.initials: PF
authors.lastname: van Kuijk
authors.affiliation: Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center Rotterdam, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands.
authors.forename: Antonius W M
authors.initials: AW
authors.lastname: Boersma
authors.affiliation: Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center Rotterdam, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands.
authors.forename: Jozien
authors.initials: J
authors.lastname: Helleman
authors.affiliation: Erasmus Center for Biomics, Erasmus University Medical Center, 3015 CN, Rotterdam, The Netherlands.
authors.forename: Wilfred F
authors.initials: WF
authors.lastname: van IJcken
authors.affiliation: Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center Rotterdam, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands.
authors.forename: Ron H J
authors.initials: RH
authors.lastname: Mathijssen
authors.affiliation: Department of Genetics, Erasmus University Medical Center, 3015 CN, Rotterdam, The Netherlands.
authors.forename: Joris
authors.initials: J
authors.lastname: Pothof
authors.affiliation: Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center Rotterdam, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands.
authors.forename: Els M J J
authors.initials: EM
authors.lastname: Berns
authors.affiliation: Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center Rotterdam, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands.
authors.forename: Jaap
authors.initials: J
authors.lastname: Verweij
authors.affiliation: Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center Rotterdam, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands. e.wiemer@erasmusmc.nl.
authors.forename: Erik A C
authors.initials: EA
authors.lastname: Wiemer
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000502:physiology*; D010051:Ovarian Neoplasms / Q000235:genetics*; D017239:Paclitaxel / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; C000599270:MIRN-634 microRNA, human; D035683:MicroRNAs; D017239:Paclitaxel; D002945:Cisplatin