title: Identifying microRNAs regulating B7-H3 in breast cancer: the clinical impact of microRNA-29c.
abstract: BACKGROUND
  B7-H3, an immunoregulatory protein, is overexpressed in several cancers and is often associated with metastasis and poor prognosis. Here, our aim was to identify microRNAs (miRNAs) regulating B7-H3 and assess their potential prognostic implications in breast cancer.
  
  
  METHODS
  MicroRNAs targeting B7-H3 were identified by transfecting two breast cancer cell lines with a library of 810 miRNA mimics and quantifying changes of B7-H3 protein levels using protein lysate microarrays. For validations we used western immunoblotting and 3'-UTR luciferase assays. Clinical significance of the miRNAs was assayed by analysing whether their expression levels correlated with outcome in two cohorts of breast cancer patients (142 and 81 patients).
  
  
  RESULTS
  We identified nearly 50 miRNAs that downregulated B7-H3 protein levels. Western immunoblotting validated the impact of the 20 most effective miRNAs. Thirteen miRNAs (miR-214, miR-363*, miR-326, miR-940, miR-29c, miR-665, miR-34b*, miR-708, miR-601, miR-124a, miR-380-5p, miR-885-3p, and miR-593) targeted B7-H3 directly by binding to its 3'-UTR region. Finally, high expression of miR-29c was associated with a significant reduced risk of dying from breast cancer in both cohorts.
  
  
  CONCLUSIONS
  We identified miRNAs efficiently downregulating B7-H3 expression. The expression of miR-29c correlated with survival in breast cancer patients, suggesting a tumour suppressive role for this miRNA.
authors.affiliation: Department of Tumor Biology, Institute of Cancer Research, Oslo University Hospital, N-0310 Oslo, Norway.
authors.forename: M K
authors.initials: MK
authors.lastname: Nygren
authors.affiliation: Department of Tumor Biology, Institute of Cancer Research, Oslo University Hospital, N-0310 Oslo, Norway.
authors.forename: C
authors.initials: C
authors.lastname: Tekle
authors.affiliation: 1] Department of Tumor Biology, Institute of Cancer Research, Oslo University Hospital, N-0310 Oslo, Norway [2] Faculty of Medicine, Institute for Clinical Medicine, University of Oslo, N-0424 Oslo, Norway.
authors.forename: V A
authors.initials: VA
authors.lastname: Ingebrigtsen
authors.affiliation: Medical Biotechnology, VTT Technical Research Centre of Finland, FI-20520 Turku, Finland.
authors.forename: R
authors.initials: R
authors.lastname: Mäkelä
authors.affiliation: 1] Department of Genetics, Institute of Cancer Research, Oslo University Hospital, N-0310 Oslo, Norway [2] The K.G. Jebsen Center for Breast Cancer Research, Institute for Clinical Medicine, Faculty of Medicine, University of Oslo, N-0424 Oslo, Norway.
authors.forename: M
authors.initials: M
authors.lastname: Krohn
authors.affiliation: 1] Department of Genetics, Institute of Cancer Research, Oslo University Hospital, N-0310 Oslo, Norway [2] The K.G. Jebsen Center for Breast Cancer Research, Institute for Clinical Medicine, Faculty of Medicine, University of Oslo, N-0424 Oslo, Norway.
authors.forename: M R
authors.initials: MR
authors.lastname: Aure
authors.affiliation: Department of Tumor Biology, Institute of Cancer Research, Oslo University Hospital, N-0310 Oslo, Norway.
authors.forename: C E
authors.initials: CE
authors.lastname: Nunes-Xavier
authors.affiliation: Medical Biotechnology, VTT Technical Research Centre of Finland, FI-20520 Turku, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Perälä
authors.affiliation: Department of Experimental Clinical Oncology, Aarhus University Hospital, DK-8000 Aarhus, Denmark.
authors.forename: T
authors.initials: T
authors.lastname: Tramm
authors.affiliation: Department of Experimental Clinical Oncology, Aarhus University Hospital, DK-8000 Aarhus, Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Alsner
authors.affiliation: Department of Experimental Clinical Oncology, Aarhus University Hospital, DK-8000 Aarhus, Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Overgaard
authors.affiliation: 1] Faculty of Medicine, Institute for Clinical Medicine, University of Oslo, N-0424 Oslo, Norway [2] Department of Pathology, The Norwegian Radium Hospital, Oslo University Hospital, N-0424 Oslo, Norway.
authors.forename: J M
authors.initials: JM
authors.lastname: Nesland
authors.affiliation: Department of Pathology, The Norwegian Radium Hospital, Oslo University Hospital, N-0424 Oslo, Norway.
authors.forename: E
authors.initials: E
authors.lastname: Borgen
authors.affiliation: 1] Department of Genetics, Institute of Cancer Research, Oslo University Hospital, N-0310 Oslo, Norway [2] The K.G. Jebsen Center for Breast Cancer Research, Institute for Clinical Medicine, Faculty of Medicine, University of Oslo, N-0424 Oslo, Norway.
authors.forename: A-L
authors.initials: AL
authors.lastname: Børresen-Dale
authors.affiliation: 1] Department of Tumor Biology, Institute of Cancer Research, Oslo University Hospital, N-0310 Oslo, Norway [2] Faculty of Medicine, Institute for Clinical Medicine, University of Oslo, N-0424 Oslo, Norway.
authors.forename: Ø
authors.initials: Ø
authors.lastname: Fodstad
authors.affiliation: 1] Department of Genetics, Institute of Cancer Research, Oslo University Hospital, N-0310 Oslo, Norway [2] The K.G. Jebsen Center for Breast Cancer Research, Institute for Clinical Medicine, Faculty of Medicine, University of Oslo, N-0424 Oslo, Norway [3] Department of Research, Vestre Viken Hospital Trust, N-3004 Drammen, Norway.
authors.forename: K K
authors.initials: KK
authors.lastname: Sahlberg
authors.affiliation: 1] Department of Genetics, Institute of Cancer Research, Oslo University Hospital, N-0310 Oslo, Norway [2] The K.G. Jebsen Center for Breast Cancer Research, Institute for Clinical Medicine, Faculty of Medicine, University of Oslo, N-0424 Oslo, Norway.
authors.forename: S-K
authors.initials: SK
authors.lastname: Leivonen
mesh_terms: D060887:B7 Antigens / Q000096:biosynthesis / Q000235:genetics*; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D018572:Disease-Free Survival; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D053208:Kaplan-Meier Estimate; D035683:MicroRNAs / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D060887:B7 Antigens; C423237:CD276 protein, human; C532045:MIRN29a microRNA, human; D035683:MicroRNAs