Validation of PDGFRbeta and c-Src tyrosine kinases as tumor/vessel targets in patients with multiple myeloma: preclinical efficacy of the novel, orally available inhibitor dasatinib

Blood. 2008 Aug 15;112(4):1346-56. doi: 10.1182/blood-2007-10-116590. Epub 2008 Jun 4.

Abstract

Inhibition of multiple myeloma (MM) plasma cells in their permissive bone marrow microenvironment represents an attractive strategy for blocking the tumor/vessel growth associated with the disease progression. However, target specificity is an essential aim of this approach. Here, we identified platelet-derived growth factor (PDGF)-receptor beta (PDGFRbeta) and pp60c-Src as shared constitutively activated tyrosine-kinases (TKs) in plasma cells and endothelial cells (ECs) isolated from MM patients (MMECs). Our cellular and molecular dissection showed that the PDGF-BB/PDGFRbeta kinase axis promoted MM tumor growth and vessel sprouting by activating ERK1/2, AKT, and the transcription of MMEC-released proangiogenic factors, such as vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8). Interestingly, pp60c-Src TK-activity was selectively induced by VEGF in MM tumor and ECs, and the use of small-interfering (si)RNAs validated pp60c-Src as a key signaling effector of VEGF loop required for MMEC survival, migration, and angiogenesis. We also assessed the antitumor/vessel activity of dasatinib, a novel orally bioactive PDGFRbeta/Src TK-inhibitor that significantly delayed MM tumor growth and angiogenesis in vivo, showing a synergistic cytotoxicity with conventional and novel antimyeloma drugs (ie, melphalan, prednisone, bor-tezomib, and thalidomide). Overall data highlight the biologic and therapeutic relevance of the combined targeting of PDGFRbeta/c-Src TKs in MM, providing a framework for future clinical trials.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Animals
  • Antineoplastic Agents
  • Dasatinib
  • Drug Delivery Systems / methods*
  • Drug Evaluation, Preclinical
  • Female
  • Humans
  • Male
  • Mice
  • Mice, SCID
  • Middle Aged
  • Multiple Myeloma / drug therapy*
  • Multiple Myeloma / enzymology
  • Multiple Myeloma / etiology
  • Protein Kinase Inhibitors
  • Pyrimidines / pharmacology*
  • Pyrimidines / therapeutic use
  • Receptor, Platelet-Derived Growth Factor beta / antagonists & inhibitors
  • Receptor, Platelet-Derived Growth Factor beta / physiology*
  • Thiazoles / pharmacology*
  • Thiazoles / therapeutic use
  • Tumor Cells, Cultured
  • Xenograft Model Antitumor Assays
  • src-Family Kinases / antagonists & inhibitors
  • src-Family Kinases / physiology*

Substances

  • Antineoplastic Agents
  • Protein Kinase Inhibitors
  • Pyrimidines
  • Thiazoles
  • Receptor, Platelet-Derived Growth Factor beta
  • src-Family Kinases
  • Dasatinib