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.
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.
Department of Internal Medicine and Clinical Oncology, University of Bari Medical School, Bari, Italy. malu.coluccia@libero.it
Addolorata Maria Luce
AM
Coluccia
Teresa
T
Cirulli
Paola
P
Neri
Domenica
D
Mangieri
Maria Cristina
MC
Colanardi
Antonio
A
Gnoni
Nicola
N
Di Renzo
Franco
F
Dammacco
Pierfrancesco
P
Tassone
Domenico
D
Ribatti
Carlo
C
Gambacorti-Passerini
Angelo
A
Vacca
D000328:Adult; D000368:Aged; D000818:Animals; D000970:Antineoplastic Agents; D000069439:Dasatinib; D016503:Drug Delivery Systems / Q000379:methods*; D004353:Drug Evaluation, Preclinical; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D016513:Mice, SCID; D008875:Middle Aged; D009101:Multiple Myeloma / Q000188:drug therapy* / Q000201:enzymology / Q000209:etiology; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines / Q000494:pharmacology* / Q000627:therapeutic use; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000037:antagonists & inhibitors / Q000502:physiology*; D013844:Thiazoles / Q000494:pharmacology* / Q000627:therapeutic use; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*
D000970:Antineoplastic Agents; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D013844:Thiazoles; D020797:Receptor, Platelet-Derived Growth Factor beta; D019061:src-Family Kinases; D000069439:Dasatinib