Signal transduction of c-Kit receptor tyrosine kinase in CHRF myeloid leukemia cells.
OBJECTIVE
The tyrosine kinase receptor c-Kit (stem cell factor receptor, CD117) is a potential target for signal transduction therapy in different cancers. In this study we investigated c-Kit in CHRF cells, a megakaryoblastic cell line of Acute Myeloid Leukemia (FAB M7).


METHODS
We characterized the interactions between c-Kit and PI 3-kinase (p85) after stimulation with SCF (stem cell factor) as well as the regulation of SHP-1 and SHP-2 associated with Kit in this cell line.


RESULTS
Stimulation with SCF leads to a significant increase in interaction between Kit and p85 as well as in receptor associated PI 3-kinase activity. Interestingly, using different kinds of substances (AG 1295, CGP 53716) to inhibit the tyrosine kinase activity of c-Kit blocked activation of c-Kit, but the association of p85 still increased after SCF stimulation even when the tyrosine kinase activity of the receptor was completely blocked. In contrast, the other known interaction partners of c-Kit, SHP-1 and SHP-2, exhibited a basal association with c-Kit and no change of the association could be detected after stimulation of CHRF cells with SCF or treatment with the kinase inhibitors.


CONCLUSIONS
Therefore, we suggest that association of p85, SHP-1, and SHP-2 to c-Kit in CHRF cells can, at least in part, occur in a c-Kit kinase-activity independent manner. In contrast, the kinase activity of c-Kit is necessary for the activation of receptor-associated PI 3-kinase.
Scholl
Sebastian
S
Department of Internal Medicine II (Hematology and Oncology), Friedrich Schiller University Jena, Germany. sebastian.scholl@med.uni-jena.de
Kirsch
Cornelia
C
Böhmer
Frank D
FD
Klinger
Reinhard
R
D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003561:Cytarabine / Q000494:pharmacology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007951:Leukemia, Myeloid / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000494:pharmacology; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D019089:Stem Cell Factor / Q000494:pharmacology; D020032:Tyrphostins / Q000494:pharmacology
C407689:6,7-dimethoxy-2-phenylquinoxaline; D047908:Intracellular Signaling Peptides and Proteins; D019089:Stem Cell Factor; D020032:Tyrphostins; D003561:Cytarabine; D019869:Phosphatidylinositol 3-Kinases; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases