The PIM inhibitor AZD1208 synergizes with ruxolitinib to induce apoptosis of ruxolitinib sensitive and resistant JAK2-V617F-driven cells and inhibit colony formation of primary MPN cells

Oncotarget. 2015 Nov 24;6(37):40141-57. doi: 10.18632/oncotarget.5653.

Abstract

Classical myeloproliferative neoplasms (MPNs) are hematopoietic stem cell disorders that exhibit excess mature myeloid cells, bone marrow fibrosis, and risk of leukemic transformation. Aberrant JAK2 signaling plays an etiological role in MPN formation. Because neoplastic cells in patients are largely insensitive to current anti-JAK2 therapies, effective therapies remain needed. Members of the PIM family of serine/threonine kinases are induced by JAK/STAT signaling, regulate hematopoietic stem cell growth, protect hematopoietic cells from apoptosis, and exhibit hematopoietic cell transforming properties. We hypothesized that PIM kinases may offer a therapeutic target for MPNs. We treated JAK2-V617F-dependent MPN model cells as well as primary MPN patient cells with the PIM kinase inhibitors SGI-1776 and AZD1208 and the JAK2 inhibitor ruxolitinib. While MPN model cells were rather insensitive to PIM inhibitors, combination of PIM inhibitors with ruxolitinib led to a synergistic effect on MPN cell growth due to enhanced apoptosis. Importantly, PIM inhibitor mono-therapy inhibited, and AZD1208/ruxolitinib combination therapy synergistically suppressed, colony formation of primary MPN cells. Enhanced apoptosis by combination therapy was associated with activation of BAD, inhibition of downstream components of the mTOR pathway, including p70S6K and S6 protein, and activation of 4EBP1. Importantly, PIM inhibitors re-sensitized ruxolitinib-resistant MPN cells to ruxolitinib by inducing apoptosis. Finally, exogenous expression of PIM1 induced ruxolitinib resistance in MPN model cells. These data indicate that PIMs may play a role in MPNs and that combining PIM and JAK2 kinase inhibitors may offer a more efficacious therapeutic approach for MPNs over JAK2 inhibitor mono-therapy.

Keywords: JAK2-V617F; MPN; PIM; kinase inhibitor; therapy.

Publication types

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

MeSH terms

  • Apoptosis / drug effects*
  • Biphenyl Compounds / pharmacology*
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Cells, Cultured
  • Drug Synergism
  • Humans
  • Imidazoles / pharmacology
  • Immunoblotting
  • Janus Kinase 2 / antagonists & inhibitors*
  • Janus Kinase 2 / genetics
  • Janus Kinase 2 / metabolism
  • Mutation
  • Myeloproliferative Disorders / genetics
  • Myeloproliferative Disorders / metabolism
  • Myeloproliferative Disorders / pathology
  • Protein Kinase Inhibitors / pharmacology
  • Proto-Oncogene Proteins c-pim-1 / antagonists & inhibitors*
  • Proto-Oncogene Proteins c-pim-1 / metabolism
  • Pyrazoles / pharmacology*
  • Pyridazines / pharmacology
  • Signal Transduction / drug effects
  • TOR Serine-Threonine Kinases / metabolism
  • Thiazolidines / pharmacology*
  • Tumor Stem Cell Assay
  • bcl-Associated Death Protein / metabolism

Substances

  • AZD1208
  • Biphenyl Compounds
  • INCB018424
  • Imidazoles
  • Protein Kinase Inhibitors
  • Pyrazoles
  • Pyridazines
  • SGI 1776
  • Thiazolidines
  • bcl-Associated Death Protein
  • TOR Serine-Threonine Kinases
  • Janus Kinase 2
  • Proto-Oncogene Proteins c-pim-1