A potential role for HSP90 inhibitors in the treatment of JAK2 mutant-positive diseases as demonstrated using quantitative flow cytometry

Leuk Lymphoma. 2007 Nov;48(11):2189-95. doi: 10.1080/10428190701607576.


The V617F mutation of the JAK2 tyrosine kinase is found in a majority of patients with myeloproliferative disorders. Flow cytometry assays for quantitation of phosphorylated and total protein for JAK2, STAT5, and heat shock proteins (HSPs) were developed to facilitate the study of the JAK/STAT pathway. A cell line homozygous for V617F (HEL) was treated with inhibitors of JAK2 tyrosine kinase activity and the HSP90 inhibitor 17-AAG. 17-AAG reduced HSP90 levels, but increased HSP70 levels. Phospho-STAT5, total STAT5, and total AKT levels were also reduced by 17-AAG treatment. Further, phospho-JAK2, total JAK2, and cell viability were reduced to a greater extent by 17-AAG than by the pan-JAK kinase family inhibitor JKII or the JAK2-specific inhibitor AG490, and these inhibitors failed to synergize with 17-AAG. Flow-cytometry-based assays for JAK/STAT signaling pathway and HSPs are likely to have broad clinical utility for monitoring patients with abnormalities in the JAK2 pathway.

MeSH terms

  • Benzoquinones / pharmacology
  • Benzoquinones / therapeutic use*
  • Drug Evaluation, Preclinical
  • Flow Cytometry / methods*
  • HSP90 Heat-Shock Proteins / analysis
  • HSP90 Heat-Shock Proteins / antagonists & inhibitors*
  • HSP90 Heat-Shock Proteins / metabolism
  • Humans
  • Janus Kinase 2 / analysis
  • Janus Kinase 2 / antagonists & inhibitors
  • Janus Kinase 2 / metabolism*
  • Lactams, Macrocyclic / pharmacology
  • Lactams, Macrocyclic / therapeutic use*
  • Mutant Proteins / metabolism
  • Myeloproliferative Disorders / drug therapy*
  • Myeloproliferative Disorders / metabolism*
  • Phosphorylation
  • Protein Kinase Inhibitors / pharmacology
  • STAT Transcription Factors / metabolism
  • Signal Transduction / drug effects
  • Tumor Cells, Cultured


  • Benzoquinones
  • HSP90 Heat-Shock Proteins
  • Lactams, Macrocyclic
  • Mutant Proteins
  • Protein Kinase Inhibitors
  • STAT Transcription Factors
  • tanespimycin
  • Janus Kinase 2