title: MicroRNA-16 is down-regulated in mutated FLT3 expressing murine myeloid FDC-P1 cells and interacts with Pim-1.
abstract: Activating mutations in the receptor tyrosine kinase FLT3 are one of the most frequent somatic mutations in acute myeloid leukemia (AML). Internal tandem duplications of the juxtamembrane region of FLT3 (FLT3/ITD) constitutively activate survival and proliferation pathways, and are associated with a poor prognosis in AML. We suspected that alteration of small non-coding microRNA (miRNA) expression in these leukemia cells is involved in the transformation process and used miRNA microarrays to determine the miRNA signature from total RNA harvested from FLT3/ITD expressing FDC-P1 cells (FD-FLT3/ITD). This revealed that a limited set of miRNAs appeared to be affected by expression of FLT3/ITD compared to the control group consisting of FDC-P1 parental cells transfected with an empty vector (FD-EV). Among differentially expressed miRNAs, we selected miR-16, miR-21 and miR-223 to validate the microarray data by quantitative real-time RT-PCR showing a high degree of correlation. We further analyzed miR-16 expression with FLT3 inhibitors in FLT3/ITD expressing cells. MiR-16 was found to be one of most significantly down-regulated miRNAs in FLT3/ITD expressing cells and was up-regulated upon FLT3 inhibition. The data suggests that miR-16 is acting as a tumour suppressor gene in FLT3/ITD-mediated leukemic transformation. Whilst miR-16 has been reported to target multiple mRNAs, computer models from public bioinformatic resources predicted a potential regulatory mechanism between miR-16 and Pim-1 mRNA. In support of this interaction, miR-16 was shown to suppress Pim-1 reporter gene expression. Further, our data demonstrated that over-expression of miR-16 mimics suppressed Pim-1 expression in FD-FLT3/ITD cells suggesting that increased miR-16 expression contributes to depletion of Pim-1 after FLT3 inhibition and that miR-16 repression may be associated with up-regulated Pim-1 in FLT3/ITD expressing cells.
authors.affiliation: School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia. kyutae.kim@gmail.com
authors.forename: Kyu-Tae
authors.initials: KT
authors.lastname: Kim
authors.forename: Adam P
authors.initials: AP
authors.lastname: Carroll
authors.forename: Baratali
authors.initials: B
authors.lastname: Mashkani
authors.forename: Murray J
authors.initials: MJ
authors.lastname: Cairns
authors.forename: Donald
authors.initials: D
authors.lastname: Small
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Scott
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D004247:DNA; D015536:Down-Regulation / Q000235:genetics*; D051379:Mice; D035683:MicroRNAs / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D051941:fms-Like Tyrosine Kinase 3 / Q000235:genetics*
chemical_list: D035683:MicroRNAs; C522604:Mirn16 microRNA, mouse; D011518:Proto-Oncogene Proteins; D004247:DNA; C497971:Flt3 protein, mouse; D051941:fms-Like Tyrosine Kinase 3; C488192:Pim3 protein, mouse; D017346:Protein Serine-Threonine Kinases