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Regulation of arsenic trioxide-induced cellular responses by Mnk1 and Mnk2.

Abstract
Arsenic trioxide (As(2)O(3)) is a potent inducer of apoptosis of malignant cells in vitro and in vivo, but the precise mechanisms by which it mediates such effects are not well defined. We provide evidence that As(2)O(3) induces phosphorylation/activation of the MAPK signal-integrating kinases (Mnks) 1 and 2 in leukemia cell lines. Such activation is defective in cells with targeted disruption of the p38alpha MAPK gene, indicating that it requires upstream engagement of the p38 MAPK pathway. Studies using Mnk1(-/-) or Mnk2(-/-), or double Mnk1(-/-)Mnk2(-/-) knock-out cells, establish that activation of Mnk1 and Mnk2 by arsenic trioxide regulates downstream phosphorylation of the eukaryotic initiation factor 4E at Ser-209. Importantly, arsenic-induced apoptosis is enhanced in cells with targeted disruption of the Mnk1 and/or Mnk2 genes, suggesting that these kinases are activated in a negative-feedback regulatory manner, to control generation of arsenic trioxide responses. Consistent with this, pharmacological inhibition of Mnk activity enhances the suppressive effects of arsenic trioxide on primary leukemic progenitors from patients with acute leukemias. Taken together, these findings indicate an important role for Mnk kinases, acting as negative regulators for signals that control generation of arsenic trioxide-dependent apoptosis and antileukemic responses.
AuthorsBlazej Dolniak, Efstratios Katsoulidis, Nathalie Carayol, Jessica K Altman, Amanda J Redig, Martin S Tallman, Takeshi Ueda, Rie Watanabe-Fukunaga, Rikiro Fukunaga, Leonidas C Platanias
JournalThe Journal of biological chemistry (J Biol Chem) Vol. 283 Issue 18 Pg. 12034-42 (May 2 2008) ISSN: 0021-9258 [Print] United States
PMID18299328 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, Non-P.H.S.)
Chemical References
  • Arsenicals
  • Enzyme Inhibitors
  • Eukaryotic Initiation Factor-4E
  • Intracellular Signaling Peptides and Proteins
  • Oxides
  • MKNK1 protein, human
  • Mknk1 protein, mouse
  • Mknk2 protein, mouse
  • MKNK2 protein, human
  • Protein-Serine-Threonine Kinases
  • Mitogen-Activated Protein Kinases
  • arsenic trioxide
Topics
  • Animals
  • Apoptosis (drug effects)
  • Arsenicals (pharmacology)
  • Blast Crisis (pathology)
  • Cell Line, Tumor
  • Cell Proliferation (drug effects)
  • Drug Screening Assays, Antitumor
  • Enzyme Activation (drug effects)
  • Enzyme Inhibitors (pharmacology)
  • Eukaryotic Initiation Factor-4E (metabolism)
  • Fibroblasts (drug effects, enzymology)
  • Gene Targeting
  • Humans
  • Intracellular Signaling Peptides and Proteins (antagonists & inhibitors, metabolism)
  • Leukemia, Promyelocytic, Acute (enzymology, pathology)
  • Mice
  • Mitogen-Activated Protein Kinases (metabolism)
  • Oxides (pharmacology)
  • Phosphorylation (drug effects)
  • Protein-Serine-Threonine Kinases (antagonists & inhibitors, metabolism)
  • Tumor Stem Cell Assay

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