title: CBL mutation-related patterns of phosphorylation and sensitivity to tyrosine kinase inhibitors.
abstract: Recurrent homozygous CBL-inactivating mutations in myeloid malignancies decrease ubiquitin ligase activity that inactivates SRC family kinases (SFK) and receptor tyrosine kinases (RTK). However, the most important SFK and RTK affected by these mutations, and hence, the most important therapeutic targets, have not been clearly characterized. We compared SFK and RTK pathway activity and inhibitors in acute myeloid leukemia cell lines containing homozygous R420Q mutation (GDM-1), heterozygous deletion (MOLM13) and wild-type (WT) CBL (THP1, U937). As expected with CBL loss, GDM-1 displayed high KIT expression and granulocyte-macrophage colony-stimulating factor (GM-CSF) hypersensitivity. Ectopic expression of WT CBL decreased GDM-1 proliferation but not cell lines with WT CBL. GDM-1, but not the other cell lines, was highly sensitive to growth inhibition by dasatinib (dual SFK and RTK inhibitor, LD50 50 nM); there was less or no selective inhibition of GDM-1 growth by sunitinib (RTK inhibitor), imatinib (ABL, KIT inhibitor), or PP2 (SFK inhibitor). Phosphoprotein analysis identified phosphorylation targets uniquely inhibited by dasatinib treatment of GDM-1, including a number of proteins in the KIT and GM-CSF receptor pathways (for example, KIT Tyr721, STAT3 Tyr705). In conclusion, the promiscuous effects of CBL loss on SFK and RTK signaling appear to be best targeted by dual SFK and RTK inhibition.
authors.affiliation: Department of Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: H
authors.initials: H
authors.lastname: Makishima
authors.forename: Y
authors.initials: Y
authors.lastname: Sugimoto
authors.forename: H
authors.initials: H
authors.lastname: Szpurka
authors.forename: M J
authors.initials: MJ
authors.lastname: Clemente
authors.forename: K P
authors.initials: KP
authors.lastname: Ng
authors.forename: H
authors.initials: H
authors.lastname: Muramatsu
authors.forename: C
authors.initials: C
authors.lastname: O'Keefe
authors.forename: Y
authors.initials: Y
authors.lastname: Saunthararajah
authors.forename: J P
authors.initials: JP
authors.lastname: Maciejewski
mesh_terms: D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D005434:Flow Cytometry; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism; D006801:Humans; D007124:Immunoenzyme Techniques; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D009154:Mutation / Q000235:genetics*; D010766:Phosphorylation / Q000187:drug effects; D011379:Prognosis; D011485:Protein Binding; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D050721:Proto-Oncogene Proteins c-cbl / Q000235:genetics* / Q000378:metabolism; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020794:Receptor Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D014407:Tumor Cells, Cultured; D019061:src-Family Kinases / Q000037:antagonists & inhibitors*
chemical_list: D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D050721:Proto-Oncogene Proteins c-cbl; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases; D019061:src-Family Kinases; C067419:CBL protein, human