A novel tyrosine kinase switch is a mechanism of imatinib resistance in gastrointestinal stromal tumors

Oncogene. 2007 Jun 7;26(27):3909-19. doi: 10.1038/sj.onc.1210173. Epub 2007 Feb 26.

Abstract

KIT or alpha-platelet-derived growth factor receptor (alpha-PDGFR) activating mutations are the pathogenic mechanisms that characterize gastrointestinal stromal tumors (GIST). Despite excellent responses to imatinib mesylate (IM), patients are relapsing. We developed an IM-resistant GIST cell line (GIST-R) from the IM-sensitive GIST882 cell line (GIST-S) by growing these cells in IM. Gene expression profiling (GEP) of GIST-S, GIST-R cells and two IM resistant GIST patients demonstrated that KIT is downregulated implying a major role in IM resistance. Instead, GIST-R cells have acquired IM resistance by overexpressing the oncogenic receptor tyrosine kinase - AXL - in a 'kinase switch'. Further, the two IM resistant GIST patients express AXL and not c-Kit, seen by immunohistochemistry (IHC). Real time reverse transcriptase-polymerase chain reaction and Western blotting of the GIST-S and GIST-R cells confirmed the switch from Kit to AXL. In GIST-R, AXL is tyrosine phosphorylated and its ligand growth-arrest-specific gene 6 is overexpressed implying autocrine activation. The kinase switch is associated with a morphological change from spindle to epithelioid. Molecular modeling of the kinase domain of mutant c-Kit (V654A) and AXL showed no binding to IM but efficient binding to MP470, a novel c-Kit/AXL kinase inhibitor. MP470 synergizes with docetaxel (taxotere) and is cytotoxic to GIST cells.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology
  • Antineoplastic Agents / therapeutic use
  • Benzamides
  • Blotting, Western
  • Cell Line, Tumor
  • Cell Shape / drug effects
  • Cell Survival / drug effects
  • Docetaxel
  • Drug Resistance, Neoplasm / genetics*
  • Drug Synergism
  • Gastrointestinal Stromal Tumors / drug therapy
  • Gastrointestinal Stromal Tumors / genetics*
  • Gastrointestinal Stromal Tumors / pathology
  • Gene Expression Regulation, Enzymologic / drug effects
  • Gene Expression Regulation, Neoplastic / drug effects
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Humans
  • Imatinib Mesylate
  • Models, Molecular
  • Mutation
  • Oligonucleotide Array Sequence Analysis
  • Oncogene Proteins / chemistry
  • Oncogene Proteins / genetics*
  • Oncogene Proteins / metabolism
  • Phosphorylation / drug effects
  • Piperazines / pharmacology*
  • Piperazines / therapeutic use
  • Protein Kinase Inhibitors / chemistry
  • Protein Kinase Inhibitors / pharmacology
  • Protein Structure, Tertiary
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-kit / chemistry
  • Proto-Oncogene Proteins c-kit / genetics*
  • Proto-Oncogene Proteins c-kit / metabolism
  • Pyrimidines / chemistry
  • Pyrimidines / pharmacology*
  • Pyrimidines / therapeutic use
  • Receptor Protein-Tyrosine Kinases / chemistry
  • Receptor Protein-Tyrosine Kinases / genetics*
  • Receptor Protein-Tyrosine Kinases / metabolism
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Taxoids / pharmacology

Substances

  • Antineoplastic Agents
  • Benzamides
  • MP470
  • Oncogene Proteins
  • Piperazines
  • Protein Kinase Inhibitors
  • Proto-Oncogene Proteins
  • Pyrimidines
  • Recombinant Fusion Proteins
  • Taxoids
  • Green Fluorescent Proteins
  • Docetaxel
  • Imatinib Mesylate
  • Proto-Oncogene Proteins c-kit
  • Receptor Protein-Tyrosine Kinases
  • axl receptor tyrosine kinase