Constitutively activating mutations of c-kit receptor tyrosine kinase confer factor-independent growth and tumorigenicity of factor-dependent hematopoietic cell lines.

摘要: The c-kit receptor tyrosine kinase (KIT) is activated upon ligand binding, thereby leading to a variety of signaling events that play fundamental role in hematopoiesis. In addition ligand-dependent activation, we have previously shown KIT constitutively ligand-independent manner by two point mutations, Val-559-->Gly (G559) mutation the juxtamembrane domain and Asp-814-->Val (V814) phosphotransferase domain. To investigate biochemical consequence biologic significance these retroviral vectors encoding KITG559 or KITV814 were introduced into murine pro-B-type Ba/F3 cells myeloid FDC-P1 cells, both which require interleukin-3 (IL-3) for their growth survival. found be phophorylated on absence stem cell factor (SCF) KIT. Chemical cross-linking analysis showed substantial fraction phosphorylated underwent dimerization even SCF, whereas did not, suggesting distinct mechanisms underlying constitutive activation G559 V814 mutations. Furthermore, expressing either show factor-independent growth, wild-type (KITWT) proliferated response SCF as well IL-3. Moreover, subcutaneous injection nude mice resulted production large tumors at all sites within 2 weeks, quickly succumbed leukemia died. These results suggest that, although may different, activating mutations function induce tumorigenic phenotype. Also, data this study raise possibility causal development hematologic malignancies.