2000 Fiscal Year Final Research Report Summary
Mechanisms underlying constitutive activation and oncogenic potential of mutant c-kit receptor tyrosine kinase
| Project/Area Number |
11670998
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Hematology
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| Research Institution | Osaka University |
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Principal Investigator |
IKEDA Hirokazu Osaka University Graduate School of Medicine, Assistant Professor, 医学系研究科, 助手 (10311755)
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| Co-Investigator(Kenkyū-buntansha) |
KITAYAMA Hitoshi Osaka University Graduate School of Medicine, Assistant Professor, 医学系研究科, 助手
MATSUMURA Itaru Osaka University Graduate School of Medicine, Assistant Professor, 医学系研究科, 助手 (00294083)
KANAKURA Yuzuru Osaka University Graduate School of Medicine, Professor, 医学系研究科, 教授 (20177489)
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| Project Period (FY) |
1999 – 2000
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| Keywords | c-kit receptor tyrosine kinase / oncogenic mutation / molecular target / tyrosine kinase inhibitor / tyrophostine / natural killer / T-cell lymphoma |
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| Research Abstract |
The c-kit receptor tyrosine kinase(KIT)plays important roles in embryonhic development, *ematopoiesis and also malignant transformation. We revealed that two point mutations, Val559-->Gly(G559)mutation in the juxtamembrane domain and Asp814-->Val(V814)mutation in the kinase domain, lead to constitutive and oncogenic activation of KIT.Since oncogenic mutants seem to alter their conformation and substrate specificity compared with wild-type(WT)KIT, they may be preferentially inhibited by some compound. Tyrophostines are a class of tyrosine kinase inhibitor either through competition for substrate on through ATP binding. When KIT-WT, KIT-G559 and KIT-V814 expression vector were transfected into an embryonic kidney cell line 293T and treated with increasing dose of tyrophostin AG1296, kinase activity of KIT-G559 protein was more effectively inhibited than that of KIT-WT, whereas that of KIT-V814 was not affected at all. When these KIT genes were introduced into a murine interleukin(IL)-3-d
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ependent cell line Ba/F3, Ba/F3-KIT-WT showed Stem Cell Factor(SCF)-dependent, while Ba/F3-KIT-G559 and Ba/F3-KIT-V814 factor-independent. AG1296 inhibited both factor-independent growth of Ba/F3-KIT-G559 and SCF-dependent growth of Ba/F3-KIT-WT in a dose dependent manner but with different potencies. AG1296 had no effect on factor-independent growth of Ba/F3-KIT-V814 or IL-3-dependent growth of Ba/F3-mock. AG1296 inhibited activation of MAP kinase more effectively in Ba/F3-KIT-G559 than in Ba/F3-KIT-WT.Furthermore, AG1296 blocked antiapoptotic activity of KIT-G559 more potently than that of KIT-WT.These results suggest that a gain-of-function KIT mutant may be used as a molecular target for cancer therapy.
Sinonasal natural killer/T-cell lymphoma is one of the major constituents of lethal midline granuloma. Since natural killerT cell expresses c-kit, we examined c-kit mutation in these cases by PCR-SSCP followed by direct sequencing. Twelve single nucleotide substitution mutations were seen in 23 cases. Furthermore, seven of eight mutations(92%)in exon 17 occurred at codon 825 and three of four mutations(75%)in exon 11 occurred at codon 56l. Although the codon 825 mutation was not a gain-of-function mutation, the mechanisms of these mutations in pathogenesis are investigated. Less
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Research Products
(4 results)
