title: The proto-oncogene Pim-1 is a target of miR-33a.
abstract: The constitutively active serine/threonine kinase Pim-1 is upregulated in different cancer types, mainly based on the action of several interleukines and growth factors at the transcriptional level. So far, a regulation of oncogenic Pim-1 by microRNAs (miRNAs) has not been reported. Here, we newly establish miR-33a as a miRNA with potential tumor suppressor activity, acting through inhibition of Pim-1. A screen for miRNA expression in K562 lymphoma, LS174T colon carcinoma and several other cell lines revealed generally low endogenous miR-33a levels relative to other miRNAs. Transfection of K562 and LS174T cells with a miR-33a mimic reduced Pim-1 levels substantially. In contrast, the cell-cycle regulator cyclin-dependent kinase 6 predicted to be a conserved miR-33a target, was not downregulated by the miR-33a mimic. Seed mutagenesis of the Pim-1 3'-untranslated region in a luciferase reporter construct and in a Pim-1 cDNA expressed in Pim-1-deficient Skov-3 cells demonstrated specific and direct downregulation of Pim-1 by the miR-33a mimic. The persistence of this effect was comparable to that of a small interfering RNA-mediated knockdown of Pim-1, resulting in decelerated cell proliferation. In conclusion, we demonstrate the potential of miR-33a to act as a tumor suppressor miRNA, which suggests miR-33a replacement therapy through delivery of miR mimics as a novel therapeutic strategy.
authors: Institute of Pharmaceutical Chemistry, Faculty of Pharmacy, Philipps-University Marburg, Marburg, Germany.
authors: M
authors: M
authors: Thomas
authors: K
authors: K
authors: Lange-Grünweller
authors: U
authors: U
authors: Weirauch
authors: D
authors: D
authors: Gutsch
authors: A
authors: A
authors: Aigner
authors: A
authors: A
authors: Grünweller
authors: R K
authors: RK
authors: Hartmann
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics*; D017209:Apoptosis; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D020869:Gene Expression Profiling; D016147:Genes, Tumor Suppressor; D057809:HEK293 Cells; D056945:Hep G2 Cells; D006801:Humans; D020014:K562 Cells; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D018716:Molecular Mimicry / Q000235:genetics; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D000090063:Proto-Oncogene Mas; D051573:Proto-Oncogene Proteins c-pim-1 / Q000235:genetics* / Q000378:metabolism; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid; D014162:Transfection
chemical_list: D020413:3' Untranslated Regions; C000715470:MAS1 protein, human; C550416:MIRN33a microRNA, human; D035683:MicroRNAs; D000090063:Proto-Oncogene Mas; C496634:PIM1 protein, human; D051573:Proto-Oncogene Proteins c-pim-1