title: Overexpression of miR-9 in mast cells is associated with invasive behavior and spontaneous metastasis.
abstract: BACKGROUND
  While microRNA (miRNA) expression is known to be altered in a variety of human malignancies contributing to cancer development and progression, the potential role of miRNA dysregulation in malignant mast cell disease has not been previously explored. The purpose of this study was to investigate the potential contribution of miRNA dysregulation to the biology of canine mast cell tumors (MCTs), a well-established spontaneous model of malignant mast cell disease.
  
  
  METHODS
  We evaluated the miRNA expression profiles from biologically low-grade and biologically high-grade primary canine MCTs using real-time PCR-based TaqMan Low Density miRNA Arrays and performed real-time PCR to evaluate miR-9 expression in primary canine MCTs, malignant mast cell lines, and normal bone marrow-derived mast cells (BMMCs). Mouse mast cell lines and BMMCs were transduced with empty or pre-miR-9 expressing lentiviral constructs and cell proliferation, caspase 3/7 activity, and invasion were assessed. Transcriptional profiling of cells overexpressing miR-9 was performed using Affymetrix GeneChip Mouse Gene 2.0 ST arrays and real-time PCR was performed to validate changes in mRNA expression.
  
  
  RESULTS
  Our data demonstrate that unique miRNA expression profiles correlate with the biological behavior of primary canine MCTs and that miR-9 expression is increased in biologically high grade canine MCTs and malignant cell lines compared to biologically low grade tumors and normal canine BMMCs. In transformed mouse malignant mast cell lines expressing either wild-type (C57) or activating (P815) KIT mutations and mouse BMMCs, miR-9 overexpression significantly enhanced invasion but had no effect on cell proliferation or apoptosis. Transcriptional profiling of normal mouse BMMCs and P815 cells possessing enforced miR-9 expression demonstrated dysregulation of several genes, including upregulation of CMA1, a protease involved in activation of matrix metalloproteases and extracellular matrix remodeling.
  
  
  CONCLUSIONS
  Our findings demonstrate that unique miRNA expression profiles correlate with the biological behavior of canine MCTs. Furthermore, dysregulation of miR-9 is associated with MCT metastasis potentially through the induction of an invasive phenotype, identifying a potentially novel pathway for therapeutic intervention.
authors: Joelle M
authors: JM
authors: Fenger
authors: Misty D
authors: MD
authors: Bear
authors: Stefano
authors: S
authors: Volinia
authors: Tzu-Yin
authors: TY
authors: Lin
authors: Bonnie K
authors: BK
authors: Harrington
authors: Cheryl A
authors: CA
authors: London
authors: Department of Veterinary Clinical Sciences, Columbus, USA. kisseberth.2@osu.edu.
authors: William C
authors: WC
authors: Kisseberth
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D004285:Dogs; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008407:Mast Cells / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000096:biosynthesis*; D009361:Neoplasm Invasiveness / Q000473:pathology
chemical_list: C541874:MIRN92 microRNA, human; D035683:MicroRNAs