title: Dasatinib inhibits B cell receptor signalling in chronic lymphocytic leukaemia but novel combination approaches are required to overcome additional pro-survival microenvironmental signals.
abstract: As antigenic stimulation of the B cell antigen receptor (BCR) is key to chronic lymphocytic leukaemia (CLL) pathogenesis, targeting dysregulated kinases involved in BCR signalling is an attractive therapeutic approach. We studied the effects of the Src/c-Abl tyrosine kinase inhibitor dasatinib on BCR signal transduction in CLL cells. Treatment of CLL cells with 100 nmol/l dasatinib induced apoptosis by an average reduction in viability of 33·7% at 48 h, with dasatinib sensitivity correlating with inhibition of Syk(Y348)  phosphorylation. Dasatinib inhibited calcium flux, phosphatidylinositol-3-kinase and mitogen-activated protein kinase activation following BCR crosslinking, and blocked the Mcl-1-dependent increase in CLL cell survival on prolonged BCR stimulation. However, the pro-apoptotic effect of dasatinib was abrogated by stromal cell contact alone or in the presence of CD154 and interleukin (IL)-4 (CD154L/IL-4 system). Whilst dasatinib retained the ability to sensitize CLL cells in stromal co-culture to both fludarabine and chlorambucil, the addition of CD154 and IL-4 rendered cells resistant to these drug combinations. We demonstrate that the HSP90 inhibitor 17-DMAG exhibited synergy with dasatinib in vitro, and moreover, induced apoptosis of CLL cells in the CD154L/IL-4 system. Our data provide evidence that dasatinib would be most clinically effective in combination with agents able to target antigen-independent microenvironmental signals.
authors.affiliation: Institute of Cancer Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow, UK.
authors.forename: Alison M
authors.initials: AM
authors.lastname: McCaig
authors.forename: Emilio
authors.initials: E
authors.lastname: Cosimo
authors.forename: Michael T
authors.initials: MT
authors.lastname: Leach
authors.forename: Alison M
authors.initials: AM
authors.lastname: Michie
mesh_terms: D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D001402:B-Lymphocytes / Q000378:metabolism* / Q000473:pathology; D016227:Benzoquinones / Q000819:agonists / Q000494:pharmacology / Q000627:therapeutic use; D023201:CD40 Ligand / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D000069439:Dasatinib; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005260:Female; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D015847:Interleukin-4 / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D047029:Lactams, Macrocyclic / Q000819:agonists / Q000494:pharmacology / Q000627:therapeutic use; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000819:agonists / Q000494:pharmacology* / Q000627:therapeutic use; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011743:Pyrimidines / Q000819:agonists / Q000494:pharmacology* / Q000627:therapeutic use; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D017154:Stromal Cells / Q000378:metabolism / Q000473:pathology; D000072377:Syk Kinase; D013844:Thiazoles / Q000819:agonists / Q000494:pharmacology* / Q000627:therapeutic use; D013997:Time Factors
chemical_list: D016227:Benzoquinones; D018841:HSP90 Heat-Shock Proteins; C508598:IL4 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D047029:Lactams, Macrocyclic; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D047428:Protein Kinase Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D011743:Pyrimidines; D011947:Receptors, Antigen, B-Cell; D013844:Thiazoles; C448659:17-(dimethylaminoethylamino)-17-demethoxygeldanamycin; D023201:CD40 Ligand; D015847:Interleukin-4; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; D000069439:Dasatinib