title: The tumour-suppressive miR-29a/b1 cluster is regulated by CEBPA and blocked in human AML.
abstract: BACKGROUND
  CCAAT/enhancer-binding protein-alpha (CEBPA) is crucial for normal granulopoiesis and is frequently disrupted in acute myeloid leukaemia (AML). Increasing evidence suggests that CEBPA exerts its effects, in parts, by regulating specific microRNAs (miRNAs), as previously shown for miR-223. The aim of this study was to investigate the genome-wide pattern of miRNAs regulated by CEBPA in myeloid cells.
  
  
  METHODS
  In Kasumi-1 cells, conditionally expressing CEBPA, we assessed the expression of 470 human miRNAs by microarray analysis. We further investigated the microarray results by qRT-PCR, luciferase reporter assays, and chromatin immunoprecipitation assays.
  
  
  RESULTS
  In all, 18 miRNAs were more than two-fold suppressed or induced after CEBPA restoration. Among these 18 miRNAs, we focused on CEBPA-mediated regulation of the tumour-suppressive miR-29b. We observed that miR-29b is suppressed in AML patients with impaired CEBPA function or loss of chromosome 7q. We found that CEBPA selectively regulates miR-29b expression on its miR-29a/b1 locus on chromosome 7q32.3, whereas miR-29b2/c on chromosome 1q32.2 is not affected.
  
  
  CONCLUSIONS
  This study reports the activation of the tumour-suppressive miR-29b by the haematopoietic key transcription factor CEBPA. Our data provide a rationale for miR-29b suppression in AML patients with loss of chromosome 7q or CEBPA deficiency.
authors.affiliation: Department of Clinical Research, University of Bern, Bern, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Eyholzer
authors.forename: S
authors.initials: S
authors.lastname: Schmid
authors.forename: L
authors.initials: L
authors.lastname: Wilkens
authors.forename: B U
authors.initials: BU
authors.lastname: Mueller
authors.forename: T
authors.initials: T
authors.lastname: Pabst
mesh_terms: D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002872:Chromosome Deletion; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics*; D035683:MicroRNAs / Q000235:genetics*; D025521:Tumor Suppressor Proteins / Q000494:pharmacology*
chemical_list: D022763:CCAAT-Enhancer-Binding Protein-alpha; C532045:MIRN29a microRNA, human; D035683:MicroRNAs; D025521:Tumor Suppressor Proteins