Suppression of programmed cell death 4 (PDCD4) protein expression by BCR-ABL-regulated engagement of the mTOR/p70 S6 kinase pathway

Nathalie Carayol, Efstratios Katsoulidis, Antonella Sassano, Jessica K. Altman, Brian Druker, Leonidas C. Platanias

Research output: Contribution to journalArticle

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Abstract

There is accumulating evidence that mammalian target of rapamycin (mTOR)-activated pathways play important roles in cell growth and survival of BCR-ABL-transformed cells. We have previously shown that the mTOR/p70 S6 kinase (p70 S6K) pathway is constitutively activated in BCR-ABL transformed cells and that inhibition of BCR-ABL kinase activity by imatinib mesylate abrogates such activation. We now provide evidence for the existence of a novel regulatory mechanism by which BCR-ABL promotes cell proliferation, involving p70 S6K-mediated suppression of expression of programmed cell death 4 (PDCD4), a tumor suppressor protein that acts as an inhibitor of cap-dependent translation by blocking the translation initiation factor eIF4A. Our data also establish that second generation BCR-ABL kinase inhibitors block activation of p70 S6K and downstream engagement of the S6 ribosomal protein in BCR-ABL transformed cells. Moreover, PDCD4 protein expression is up-regulated by inhibition of the BCR-ABL kinase in K562 cells and BaF3/BCR-ABL transfectants, suggesting a mechanism for the generation of the proapoptotic effects of such inhibitors. Knockdown of PDCD4 expression results in reversal of the suppressive effects of nilotinib and imatinib mesylate on leukemic progenitor colony formation, suggesting an important role for this protein in the generation of antileukemic responses. Altogether, our studies identify a novel mechanism by which BCR-ABL may promote leukemic cell growth, involving sequential engagement of the mTOR/p70 S6K pathway and downstream suppression of PDCD4 expression.

Original languageEnglish (US)
Pages (from-to)8601-8610
Number of pages10
JournalJournal of Biological Chemistry
Volume283
Issue number13
DOIs
StatePublished - Mar 28 2008

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70-kDa Ribosomal Protein S6 Kinases
Apoptosis Regulatory Proteins
Cell death
Sirolimus
Cell Death
Phosphotransferases
Cell growth
Proteins
Chemical activation
Ribosomal Protein S6
Tumor Suppressor Proteins
Cohort Effect
Peptide Initiation Factors
K562 Cells
Cell proliferation
Growth
Cell Survival
Cell Proliferation
Imatinib Mesylate

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

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Suppression of programmed cell death 4 (PDCD4) protein expression by BCR-ABL-regulated engagement of the mTOR/p70 S6 kinase pathway. / Carayol, Nathalie; Katsoulidis, Efstratios; Sassano, Antonella; Altman, Jessica K.; Druker, Brian; Platanias, Leonidas C.

In: Journal of Biological Chemistry, Vol. 283, No. 13, 28.03.2008, p. 8601-8610.

Research output: Contribution to journalArticle

Carayol, Nathalie ; Katsoulidis, Efstratios ; Sassano, Antonella ; Altman, Jessica K. ; Druker, Brian ; Platanias, Leonidas C. / Suppression of programmed cell death 4 (PDCD4) protein expression by BCR-ABL-regulated engagement of the mTOR/p70 S6 kinase pathway. In: Journal of Biological Chemistry. 2008 ; Vol. 283, No. 13. pp. 8601-8610.
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