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Updated: May 25, 2026

A Method for Screening and Validation of Resistant Mutations Against Kinase Inhibitors
Published on: December 7, 2014
CBL mutation-related patterns of phosphorylation and sensitivity to tyrosine kinase inhibitors
H Makishima1, Y Sugimoto, H Szpurka
1Department of Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
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.
Insights
CBL mutations in myeloid cancers impair signaling pathways. Dual SRC and RTK inhibitors, like dasatinib, effectively target these mutations, offering a promising therapeutic strategy.
Area of Science:
- Oncology
- Molecular Biology
- Signal Transduction
Background:
- CBL mutations reduce ubiquitin ligase activity, affecting SRC family kinases (SFK) and receptor tyrosine kinases (RTK).
- The specific SFK and RTK targets most impacted by CBL mutations remain unclear, hindering precise therapeutic strategies.
Purpose of the Study:
- To compare SFK and RTK pathway activity and inhibitor responses in acute myeloid leukemia (AML) cell lines with varying CBL mutations.
- To identify the most effective therapeutic targets for AML with CBL-inactivating mutations.
Main Methods:
- Utilized AML cell lines with homozygous R420Q CBL mutation (GDM-1), heterozygous deletion (MOLM13), and wild-type (WT) CBL (THP1, U937).
- Assessed SFK and RTK pathway activity and sensitivity to inhibitors including dasatinib, sunitinib, imatinib, and PP2.
- Performed phosphoprotein analysis to identify dasatinib-inhibited targets in GDM-1 cells.
Main Results:
- GDM-1 cells exhibited high KIT expression and granulocyte-macrophage colony-stimulating factor (GM-CSF) hypersensitivity, characteristic of CBL loss.
- GDM-1 cells showed high sensitivity to dasatinib (dual SFK/RTK inhibitor), unlike other cell lines or those treated with RTK or SFK-specific inhibitors.
- Dasatinib uniquely inhibited phosphorylation of KIT and GM-CSF receptor pathway proteins (e.g., KIT Tyr721, STAT3 Tyr705) in GDM-1 cells.
Conclusions:
- CBL loss broadly affects SFK and RTK signaling in AML.
- Dual inhibition of SFK and RTK pathways is the most effective strategy for targeting AML with CBL-inactivating mutations.
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