Phosphorylation of tyrosine 393 in the kinase domain of Bcr-Abl influences the sensitivity towards imatinib in vivo

C. Miething, C. Mugler, R. Grundler, J. Hoepfl, R. Y. Bai, C. Peschel, Justus Duystel

Research output: Contribution to journalArticle

Abstract

The Bcr-Abl fusion protein arising through the t(9;22)(q34;q11) reciprocal translocation is the causative agent in chronic myeloid leukemia and a subset of acute lymphocytic leukemia. Imatinib mesylate is a specific inhibitor of the Bcr-Abl kinase and has shown promising results in clinical studies. The structural relation between the Bcr-Abl oncogene and the tyrosine kinase inhibitor imatinib has recently been elucidated by an elegant crystal structure analysis, emphasizing the importance of dephosphorylated tyrosine 393 (Tyr393) in Bcr-Abl for access of the inhibitor to the kinase domain. By mutating this tyrosine to phenylalanine and thereby mimicking a constitutively dephosphorylated state, we now show that Ba/F3 cells transformed by this mutant demonstrate an increased sensitivity towards imatinib in vivo. This effect is not due to an impaired kinase activity of Bcr-Abl Y393F, since a synthetic substrate is phosphorylated with similar kinetics. Treatment of Ba/F3 cells transfected with Bcr-Abl wild type with a phosphatase inhibitor diminished the effect of imatinib, but did not influence the growth of Ba/F3 cells transfected with Bcr-AblY393F. The results support the findings of the crystal structure and indicate that Tyr393 indeed plays a significant role for the sensitivity of Bcr-Abl towards imatinib in vivo. These data implicate the regulation of Tyr393 phosphorylation as a potential mechanism of imatinib resistance.

Original languageEnglish (US)
Pages (from-to)1695-1699
Number of pages5
JournalLeukemia
Volume17
Issue number9
DOIs
StatePublished - Sep 1 2003
Externally publishedYes

Keywords

  • Ba/F3
  • Bcr-Abl
  • Drug resistance
  • Imatinib
  • STI571
  • Tyrosine kinase inhibitor

ASJC Scopus subject areas

  • Hematology
  • Oncology
  • Cancer Research

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