The proto-oncogene Pim-1 is a target of miR-33a

Oncogene. 2012 Feb 16;31(7):918-28. doi: 10.1038/onc.2011.278. Epub 2011 Jul 11.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3' Untranslated Regions / genetics*
  • Apoptosis
  • Base Sequence
  • Binding Sites / genetics
  • Blotting, Western
  • Cell Line, Tumor
  • Cell Proliferation
  • Gene Expression Profiling
  • Genes, Tumor Suppressor
  • HEK293 Cells
  • Hep G2 Cells
  • Humans
  • K562 Cells
  • MicroRNAs / genetics*
  • MicroRNAs / metabolism
  • Molecular Mimicry / genetics
  • Neoplasms / genetics
  • Neoplasms / metabolism
  • Neoplasms / pathology
  • Proto-Oncogene Proteins c-pim-1 / genetics*
  • Proto-Oncogene Proteins c-pim-1 / metabolism
  • RNA Interference
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sequence Homology, Nucleic Acid
  • Transfection


  • 3' Untranslated Regions
  • MIRN33a microRNA, human
  • MicroRNAs
  • PIM1 protein, human
  • Proto-Oncogene Proteins c-pim-1