FLT3-ITD-TKD dual mutants associated with AML confer resistance to FLT3 PTK inhibitors and cytotoxic agents by overexpression of Bcl-x(L)

Ksenia Bagrintseva; Stefanie Geisenhof; Ruth Kern; Sabine Eichenlaub; Carola Reindl; Joachim W Ellwart; Wolfgang Hiddemann; Karsten Spiekermann

doi:10.1182/blood-2004-06-2459

FLT3-ITD-TKD dual mutants associated with AML confer resistance to FLT3 PTK inhibitors and cytotoxic agents by overexpression of Bcl-x(L)

Blood. 2005 May 1;105(9):3679-85. doi: 10.1182/blood-2004-06-2459. Epub 2004 Dec 30.

Authors

Ksenia Bagrintseva¹, Stefanie Geisenhof, Ruth Kern, Sabine Eichenlaub, Carola Reindl, Joachim W Ellwart, Wolfgang Hiddemann, Karsten Spiekermann

Affiliation

¹ Department of Medicine III, University Hospital Grosshadern, CCG "Leukemia," GSF-National Research Center for Environment and Health, Marchioninistr 25, 81377 Munich, Germany.

PMID: 15626738
DOI: 10.1182/blood-2004-06-2459

Abstract

FLT3 (fms-like tyrosine kinase 3) is constitutively activated in about 30% of patients with acute myeloid leukemia (AML) and represents a disease-specific molecular marker. Although FLT3-LM (length mutation) and TKD (tyrosine kinase domain) mutations have been considered to be mutually exclusive, 1% to 2% of patients carry both mutations. However, the functional and clinical significance of this observation is unclear. We demonstrate that FLT3-ITD-TKD dual mutants induce drug resistance toward PTK inhibitors and cytotoxic agents in in vitro model systems. As molecular mechanisms of resistance, we found that FLT3-ITD-TKD mutants cause hyperactivation of STAT5 (signal transducer and activator of transcription-5), leading to upregulation of Bcl-x(L) and RAD51 and arrest in the G(2)M phase of the cell cycle. Overexpression of Bcl-x(L) was identified as the critical mediator of drug resistance and recapitulates the PTK inhibitor and daunorubicin-resistant phenotype in FLT3-ITD cells. The combination of rapamycin, a selective mTOR inhibitor, and FLT3 PTK inhibitors restored the drug sensitivity in FLT3 dual mutant-expressing cells. Our data provide the molecular basis for understanding clinical FLT3 PTK inhibitor resistance and point to therapeutical strategies to overcome drug resistance in patients with AML.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Acute Disease
Animals
Cell Line
DNA-Binding Proteins / drug effects
DNA-Binding Proteins / genetics
Drug Resistance, Neoplasm / drug effects*
Enzyme Inhibitors / pharmacology
Humans
Leukemia, Myeloid / drug therapy*
Mice
Milk Proteins / drug effects
Point Mutation*
Protein-Tyrosine Kinases / antagonists & inhibitors*
Protein-Tyrosine Kinases / genetics
Proto-Oncogene Proteins / antagonists & inhibitors*
Proto-Oncogene Proteins / genetics
Proto-Oncogene Proteins c-bcl-2 / genetics
Rad51 Recombinase
Receptor Protein-Tyrosine Kinases / antagonists & inhibitors*
Receptor Protein-Tyrosine Kinases / genetics
Recombinant Fusion Proteins / genetics
Recombinant Fusion Proteins / pharmacology*
STAT5 Transcription Factor
Tandem Repeat Sequences*
Trans-Activators / drug effects
Transfection
Up-Regulation / drug effects
bcl-X Protein
fms-Like Tyrosine Kinase 3

Substances

BCL2L1 protein, human
Bcl2l1 protein, mouse
DNA-Binding Proteins
Enzyme Inhibitors
Milk Proteins
Proto-Oncogene Proteins
Proto-Oncogene Proteins c-bcl-2
Recombinant Fusion Proteins
STAT5 Transcription Factor
Trans-Activators
bcl-X Protein
FLT3 protein, human
Flt3 protein, mouse
Protein-Tyrosine Kinases
Receptor Protein-Tyrosine Kinases
fms-Like Tyrosine Kinase 3
RAD51 protein, human
Rad51 Recombinase
Rad51 protein, mouse