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|Ref Type||Journal Article|
|Authors||Frost MJ, Ferrao PT, Hughes TP, Ashman LK|
|Title||Juxtamembrane mutant V560GKit is more sensitive to Imatinib (STI571) compared with wild-type c-kit whereas the kinase domain mutant D816VKit is resistant.|
|Journal||Molecular cancer therapeutics|
|Abstract Text||Imatinib (Glivec; STI571) is an ATP-competitive kinase inhibitor of c-Abl, BCR/ABL, c-Kit, and platelet-derived growth factor receptor. Overexpression or constitutive activation of Kit by mutations have been associated with various malignancies. Mutations in the intracellular juxtamembrane region of Kit (e.g., V560G) are common in gastrointestinal stromal tumors and have been linked to poor prognosis. Mutations in the kinase domain of Kit (e.g., D816V) have been detected in mastocytosis, acute myeloid leukemia, and germ-cell tumors. To determine the sensitivity of Kit mutants to Imatinib in the same cellular background, wild-type Kit (WTKit), V560GKit and D816VKit were expressed in FDC-P1 cells. Growth of FDC(WTKit) was inhibited by Imatinib with GI50 (a concentration of drug at which 50% inhibition of growth occurs) of 0.1-0.2 microM but FDC(V560GKit) were more sensitive to Imatinib with a GI50 of 0.01-0.025 microM and FDC(D816VKit) were resistant to Imatinib with a GI50 greater than 5 microM. The naturally occurring isoforms of c-Kit did not differ in their sensitivity to Imatinib. Immunoprecipitation and Western blot analysis indicated that 1 microM Imatinib reduced phosphorylation of WTKit and completely blocked phosphorylation of V560GKit but did not affect D816VKit phosphorylation. In signaling studies, addition of stem cell factor (SCF) induced phosphorylation of ERK and Akt by WTKit, and ERK, Akt and STAT3 by V560GKit, which were all blocked by Imatinib. Imatinib also blocked the constitutive activation of Akt and STAT3 by V560GKit but had no affect on the constitutive activation of ERK, Akt, and STAT3 by D816VKit. Overall, these findings demonstrate the increased susceptibility of the Kit juxtamembrane mutant, V560G, and the resistance of the kinase domain mutant, D816V, to Imatinib compared with WTKit.|
|Molecular Profile||Treatment Approach|
|Gene Name||Source||Synonyms||Protein Domains||Gene Description||Gene Role|
|Therapy Name||Drugs||Efficacy Evidence||Clinical Trials|
|Drug Name||Trade Name||Synonyms||Drug Classes||Drug Description|
|Gene||Variant||Impact||Protein Effect||Variant Description||Associated with drug Resistance|
|Molecular Profile||Indication/Tumor Type||Response Type||Therapy Name||Approval Status||Evidence Type||Efficacy Evidence||References|
|KIT D816V||hematologic cancer||resistant||Imatinib||Preclinical||Actionable||In a preclinical study, a mouse myeloid cell line expressing KIT D816V demonstrated resistance to Gleevec (imatinib) in culture (PMID: 12481435).||12481435|