The Kit-activating mutation D816V enhances stem cell factor–dependent chemotaxis

Blood ◽  
2001 ◽  
Vol 98 (4) ◽  
pp. 1195-1199 ◽  
Author(s):  
Marcia L. Taylor ◽  
Jaroslaw Dastych ◽  
Devinder Sehgal ◽  
Magnus Sundstrom ◽  
Gunnar Nilsson ◽  
...  

The D816V mutation of c-kit has been detected in patients with mastocytosis. This mutation leads to constitutive tyrosine kinase activation of Kit. Because stem cell factor (SCF), the ligand for Kit (CD117+), is a chemoattractant for CD117+ cells and one feature of mastocytosis is an abnormal collection of mast cells in tissues derived from CD34+CD117+ mast cell precursors, the hypothesis was considered that the D816V mutation would enhance chemotaxis of these precursor cells. Constructs encoding wild-type Kit or Kit bearing the D816V mutation were transfected into Jurkat cells, labeled with Calcein-am, and migration to SCF assessed in the presence or absence of tyrosine kinase inhibitors. Chemotaxis to SCF was enhanced in D816V transfectants compared to wild-type Kit transfectants (P < .002). Migration of both transfectants was inhibited by tyrosine kinase inhibitors, although D816V transfectants were more sensitive. Chemotaxis was next performed on CD34+CD117+ circulating mast cell precursors obtained from patients with mastocytosis. Analysis of prechemotaxis and migrated cells showed that whereas less than 10% in the prechemotaxis sample had the D816V mutation, 40% to 80% of migrated cells had this mutation. These results demonstrate that the D816V Kit mutation enhances chemotaxis of CD117+ cells, offering one explanation for increased mast cells observed in tissues of patients with mastocytosis.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3528-3528 ◽  
Author(s):  
Srdan Verstovsek ◽  
Cem Akin ◽  
Giles J. Francis ◽  
Manshouri Taghi ◽  
Ly Huynh ◽  
...  

Abstract Background. Majority of adult patients with systemic mastocytosis (SM) have activating mutation in codon 816 of c-kit (CD117), a receptor on the surface of mast cells. This abnormality is responsible for the pathogenesis of the disease. Methods. We investigated the effects of a newly designed tyrosine kinase inhibitor, AMN107, by comparing its in vitro inhibitory potency on c-kit mutated mast cell lines and patient samples with that of imatinib mesylate, another tyrosine kinase inhibitor, effective in some patients with SM. Two cell lines, subclones of HMC-1 cells, were used: HMC-1560 carrying juxtamembrane domain mutation in codon 560 of c-kit, and HMC-1560, 816 carrying both codon 560 mutation and tyrosine kinase domain mutation in codon 816 of c-kit. Results. In HMC-1560 mast cell line carrying wild-type codon 816, AMN107 was as potent as imatinib in inhibiting cellular proliferation, with IC50 values of 108 and 74 nM respectively, while in HMC-1560, 816 cell line carrying 816 mutation, neither medication had an effect. AMN107 was also as effective as imatinib in inhibiting phosphorylation of c-kit tyrosine kinase in HMC-1560 cells. The inhibition of cellular proliferation was associated with induction of apoptosis in HMC-1560 cells. AMN107 in concentrations up to 1 uM had no effect on bone marrow mast cells carrying D816V c-kit mutation obtained from patients with mastocytosis. Conclusions. Our results suggest similar potency of AMN107 and imatinib in mast cells that carry wild-type codon 816, but no activity against codon 816 mutation carrying cells.


2014 ◽  
Vol 353 (1) ◽  
pp. 115-123 ◽  
Author(s):  
Yanli Jin ◽  
Ke Ding ◽  
Deping Wang ◽  
Mengjie Shen ◽  
Jingxuan Pan

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 526-526 ◽  
Author(s):  
Karoline V. Gleixner ◽  
Matthias Mayerhofer ◽  
Karoline Sonneck ◽  
Alexander Gruze ◽  
Puchit Samorapoompichit ◽  
...  

Abstract In a majority of all patients with systemic mastocytosis (SM) including aggressive SM and mast cell leukemia (MCL), neoplastic cells display the D816V-mutated variant of KIT. The respective oncoprotein, KIT-D816V, exhibits constitutive tyrosine kinase (TK) activity and has been implicated in malignant cell growth. Therefore, several attempts have been made to identify KIT-D816V-targeting drugs. We found that the TK-inhibitor dasatinib (BMS-354825) inhibits TK activity of wild type (wt) KIT and KIT-D816V in Ba/F3 cells with doxycycline-inducible KIT-expression. In addition, dasatinib was found to inhibit KIT D816V-induced cluster formation and viability in Ba/F3 cells as well as growth of HMC-1.1 cells (KIT-D816V-negative) and HMC-1.2 cells (KIT-D816V-positive). The effects of dasatinib on growth of HMC-1 cells were dose-dependent, with 100–1,000-fold higher IC50-values in cells harbouring KIT-D816V compared to cells lacking KIT-D816V. Furthermore, dasatinib was found to inhibit the growth of primary neoplastic mast cells in SM in all patients examined. The inhibitory effects of dasatinib in HMC-1 cells were found to be associated with apoptosis and a decrease in expression of CD2 and CD63 as determined by flow cytometry. In addition, dasatinib was found to cooperate with the tyrosine kinase inhibitors PKC412 (midostaurin), AMN107 (nilotinib), and STI571 (imatinib), as well as with 2CdA (cladribine) in producing growth-inhibition in neoplastic mast cells. In HMC-1.1 cells, all drug-interactions applied were found to be synergistic. By contrast, in HMC-1.2 cells, only the combinations “dasatinib+PKC412” and “dasatinib+2CdA” were found to produce synergistic effects. These drug-combinations may thus represent an interesting pharmacologic approach for the treatment of patients with aggressive systemic mastocytosis or mast cell leukemia.


1992 ◽  
Vol 175 (1) ◽  
pp. 245-255 ◽  
Author(s):  
B K Wershil ◽  
M Tsai ◽  
E N Geissler ◽  
K M Zsebo ◽  
S J Galli

Interactions between products of the mouse W locus, which encodes the c-kit tyrosine kinase receptor, and the Sl locus, which encodes a ligand for c-kit receptor, which we have designated stem cell factor (SCF), have a critical role in the development of mast cells. Mice homozygous for mutations at either locus exhibit several phenotypic abnormalities including a virtual absence of mast cells. Moreover, the c-kit ligand SCF can induce the proliferation and maturation of normal mast cells in vitro or in vivo, and also can result in repair of the mast cell deficiency of Sl/Sld mice in vivo. We now report that administration of SCF intradermally in vivo results in dermal mast cell activation and a mast cell-dependent acute inflammatory response. This effect is c-kit receptor dependent, in that it is not observed when SCF is administered to mice containing dermal mast cells expressing functionally inactive c-kit receptors, is observed with both glycosylated and nonglycosylated forms of SCF, and occurs at doses of SCF at least 10-fold lower on a molar basis than the minimally effective dose of the classical dermal mast cell-activating agent substance P. These findings represent the first demonstration in vivo that a c-kit ligand can result in the functional activation of any cellular lineage expressing the c-kit receptor, and suggest that interactions between the c-kit receptor and its ligand may influence mast cell biology through complex effects on proliferation, maturation, and function.


2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Jayna Stohlman ◽  
Derek Schocken ◽  
Jose Vicente ◽  
Dulciana Chan ◽  
Lars Johannesen ◽  
...  

Tyrosine kinase inhibitors (TKIs) have improved targeted therapeutics for cancer management despite possible cardiac side effects, including decreased contractility. A combination microelectrode and impedance platform was used to assess field potential (FP) electrical activity and contractility, respectively, after acute and chronic exposure of six TKIs on human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs). Four non-TKI drugs were tested to confirm assay sensitivity. hERG current inhibitors dofetilide and pentamidine increased beat rate (BR) corrected FP duration (FPDc). Dofetilide (6μM) induced transient early afterdepolarizations (EADs), characterized as ectopic beats/notching in the FP signal, and decreased impedance amplitude (BAmp) at 48hrs. Multi-channel blocker amiodarone (2μM) acutely decreased FPDc, with quiescence up to 1hr, and increased BAmp after 24hrs. Doxorubicin decreased BAmp, inducing quiescence starting at 48hrs (5μM and 10μM). Nilotinib, sorafenib and sunitinib, which have varying documented risks of clinical QT prolongation and/or cardiotoxicity, increased FPDc. With highest tested doses, nilotinib (6μM) generated persistent EADs and increased BR, sunitinib (2.5μM) produced tachyarrhythmias with minimal impedance-evident contractions that recovered by 24hrs, and sorafenib (10μM) induced quiescence that recovered by 3hrs. Imatinib, erlotinib and lapatinib, which have fewer clinical cardtiotoxic effects, did not cause rhythm disturbances. Erlotinib and lapatinib had no significant effect on FPDc, lapatinib (2.5μM and 5μM) decreased BR, while imatinib (15μM) acutely increased FPDc and increased BR after 48hrs. Tandem electrical and impedance screening in hiPSC-CMs for drug cardiotoxicity was consistent with the clinical experience for TKIs, suggesting its potential utility for preclinical cardiotoxicity assessment for proarrhythmia and decreased contractility.


Blood ◽  
1995 ◽  
Vol 85 (1) ◽  
pp. 57-65 ◽  
Author(s):  
D Rennick ◽  
B Hunte ◽  
G Holland ◽  
L Thompson-Snipes

Stem cell factor (SCF) possesses many mast cell-stimulating activities, including the ability to support the growth of mucosal-like mast cells (MMCs) and connective tissue mast cells (CTMCs). However, this study shows that, in the absence of accessory cells, SCF does not stimulate the clonal growth of primitive mast cell progenitors. Nevertheless, SCF exhibited potent growth-promoting effects when combined with the cytokines interleukin-3 (IL-3), interleukin-4 (IL-4), and interleukin- 10 (IL-10). Our comparative studies have shown that optimal mast cell colony formation occurs when both IL-4 and IL-10 are combined with SCF. However, in the presence of SCF, these two cofactors appear to mediate different effects. IL-4 was more efficient than IL-10 in costimulating the initiation of SCF-dependent colony formation by mast cell progenitors and in sustaining the proliferation of newly generated progeny. On the other hand, IL-4 was less efficient than IL-10 in supporting mast cell differentiation, as evidenced by morphology, cell enlargement, and granule production. Although the actions of IL-4 and IL-10 were not equivalent, additional experiments indicated that their ability to serve as early- and late-acting factors, respectively, were complimentary. We have also found that the mast cells generated in colonies stimulated by IL-4, IL-10, and SCF produced high levels of histamine (6–8 pg per cell). None of the mast cells generated in our cultures synthesized heparin. A phenotypic change from safranin- negative to safranin-positive cells associated with heparin-producing CTMCs was accomplished after coculture of the mast cells with fibroblast cell lines derived from normal mice or from SI/SId mice plus soluble factors. Collectively, our observations demonstrate that SCF acts as a competence factor for mast cell progenitor growth. In addition, the ability of SCF to support certain stages of mast cell differentiation is profoundly influenced by interactions with specific cofactors.


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