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c-Cbl tyrosine phosphorylation and subcellular localization in human primary leukemic cells
M F Brizzi1, A Rosso, P Dentelli
1Department of Internal Medicine, University of Turin, Italy.
Experimental Hematology
|December 9, 1998
Summary
The proto-oncogene c-Cbl is constitutively tyrosine phosphorylated in various leukemia cells, suggesting a common role in myeloid and lymphoid progenitor cell transformation.
Area of Science:
- Oncology
- Molecular Biology
- Hematology
Background:
- Signal-transducing molecules are often constitutively activated in leukemia.
- The function of the proto-oncogene c-Cbl is not fully understood.
- Constitutive activation of signaling pathways is implicated in leukemia progression.
Purpose of the Study:
- To investigate the role of c-Cbl in different types of leukemia.
- To determine if c-Cbl is constitutively tyrosine phosphorylated in leukemia cells.
- To analyze the interactions and subcellular localization of c-Cbl in leukemia.
Main Methods:
- Western blotting to detect tyrosine phosphorylation of c-Cbl.
- Immunoprecipitation to study protein-protein interactions (c-Cbl with CrkL and Grb2).
- Subcellular fractionation to analyze c-Cbl localization.
Main Results:
- c-Cbl is constitutively tyrosine phosphorylated in chronic myelogenous leukemia (CML) blast phase, acute myeloblastic leukemia (AML), and acute lymphoblastic leukemia (ALL) cells.
- c-Cbl forms stable complexes with Grb2 in leukemia blasts.
- c-Cbl is found in cytosolic, membrane, and detergent-insoluble fractions in leukemia cells and CML patient neutrophils.
Conclusions:
- Constitutive tyrosine phosphorylation of c-Cbl and its association with the detergent-insoluble fraction are common events in AML and ALL.
- These findings suggest a shared mechanism in the neoplastic transformation of myeloid and lymphoid progenitor cells involving c-Cbl.
- c-Cbl may play a significant role in the pathogenesis of various leukemias.