Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P10721 (c-kit)
 6,575 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Imatinib mesylate (imatinib) is a potent and selective inhibitor of the tyrosine kinases, Bcr-Abl, c-Kit and platelet-derived growth factor receptors (PDGFRs). Recently, it has been reported that imatinib also targets the macrophage colony-stimulating factor (M-CSF) receptor c-Fms. M-CSF signals are essential for the differentiation of osteoclasts. Bone metastases of breast cancer are frequently associated with osteoclastic bone destruction. Furthermore, several lines of evidence suggest that osteoclasts play central roles in the development and progression of bone metastases. Thus, in the present study, we examined the effects of imatinib on bone metastases of breast cancer. Coimmunoprecipitation assays showed that imatinib inhibited the M-CSF-induced phosphorylation of c-Fms in osteoclast precursor cells as well as the PDGF-induced PDGFR phosphorylation in MDA-MB-231 human breast cancer cells. Imatinib also markedly reduced osteoclast formation in vitro. In contrast, those concentrations of imatinib did not affect osteoblast differentiation. We then examined the effects of imatinib on bone metastases of MDA-MB-231 cells in a nude mouse model. Radiographic and histomorphometric analyses demonstrated that imatinib significantly decreased bone metastases associated with the reduced number of osteoclasts. In support of the notion that the inhibition of c-Fms acts to suppress the development of bone metastases, we found that a specific inhibitor of c-Fms Ki20227 also decreased bone metastases. In conclusion, these results collectively suggest that imatinib reduced bone metastases, at least in part, by inhibiting osteoclastic bone destruction through the blockade of c-Fms signals. Our results also suggest that imatinib may have a protective effect against cancer treatment-induced bone loss.
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PMID:Imatinib mesylate suppresses bone metastases of breast cancer by inhibiting osteoclasts through the blockade of c-Fms signals. 1881 79

Imatinib is a receptor tyrosine kinase inhibitor that blocks the activity of c-Abl, c-Kit, and PDGF receptors. We tested the protective effects of imatinib in thymic stromal lymphopoietin transgenic mice, a model of cryoglobulinemia and associated membranoproliferative glomerulonephritis (MPGN), in which some glomerular manifestations likely result from PDGF receptor activation. Surprising, administration of imatinib beginning at weaning suppressed production of cryoglobulin, attenuating both the renal injury and systemic features of cryoglobulinemia. Flow cytometry suggested that inhibition of B cell development in the bone marrow likely caused the reduction in cryoglobulin production. In addition, administration of imatinib to thymic stromal lymphopoietin transgenic mice with established MPGN also diminished cryoglobulin production and reversed the renal and systemic lesions. These data suggest that treatment with imatinib may be a novel therapeutic approach for cryoglobulinemia and MPGN in humans.
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PMID:Imatinib suppresses cryoglobulinemia and secondary membranoproliferative glomerulonephritis. 1902 5

Imatinib is currently in early clinical trials as targeted therapy for relapsed neuroblastomas and other childhood solid tumors expressing platelet-derived growth factor receptors (PDGFR) or c-Kit. Short-term treatment with imatinib in clinically achievable concentrations is ineffective in neuroblastoma in vitro. However, clinically, imatinib is administered daily over long time periods. The effects of combining imatinib with chemotherapy in neuroblastoma are unknown. Here, a panel of neuroblastoma cell lines (n = 5) were studied, representing tumors with different biological (MYCN-amplification +/-) and clinical (drug resistance) features. Using a protracted low-dose treatment schedule (1-3 weeks; 0.5-5microM) imatinib dose-dependently inhibited proliferation and clonogenic survival for all tested cell lines with IC50 <2.5microM. In contrast, short-term treatment (<96 hrs) was ineffective. Low-dose imatinib was synergistic in combination with doxorubicin and caused increased G2/M- and S-phase arrest and apoptosis as evidenced by enhanced caspase-3 activation and sub-G1 DNA accumulation. A significant but less pronounced effect was observed when imatinib was combined with etoposide or vincristine, as opposed to cisplatin, melphalan, or irinotecan. All cell lines expressed PDGFRbeta, whereas no protein expression of PDGFRalpha was detected in MYCN amplified cell lines. PDGF-BB caused PDGFRbeta phosphorylation and partially rescued neuroblastoma cells from doxorubicin-induced apoptosis, in an imatinib-sensitive manner. In vivo, treatment with imatinib in combination with doxorubicin induced a significant growth inhibition of established neuroblastoma xenografts. These findings suggest clinical testing of imatinib in combination with selected chemotherapeutic drugs, in particular doxorubicin, in children with high-risk neuroblastoma.
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PMID:Metronomic scheduling of imatinib abrogates clonogenicity of neuroblastoma cells and enhances their susceptibility to selected chemotherapeutic drugs in vitro and in vivo. 1905 99

Vascular endothelial Flt-1 and other stem cell markers are variably expressed in vascular smooth muscle cells (SMCs) during normal and pathological conditions, but their biological role remains uncertain. In normal rat aorta, rare flt-1+ and c-kit+ SMCs were detected. Fifteen days after injury, 61.8 +/- 3.8, 45.7 +/- 3% of the intimal cells resulted flt-1+ and c-kit+ and expressed low level of alpha-smooth muscle actin; CD133+ cells were 5.6 +/- 0.7%. BrDU+/flt-1+ largely predominated in the neointima, whereas BrDU+/CD133+ cells were rare. Forty-five and sixty days after injury, intimal proliferation such as BrDU+ cells was greatly reduced. After sixty days, intimal stem marker expression had almost disappeared whereas alpha-smooth muscle actin was restored. Flk-1 and Oct-4 SMC immunodection was consistently negative. In vitro, intimal cells obtained fifteen days after injury exhibited an epithelioid phenotype and increased flt-1 and c-kit protein and mRNA and low smooth muscle markers compared to spindle-shaped medial and intimal SMCs obtained after sixty days. Epithelioid clones, independently from layer of origin, were similar in stem cell marker expression. The anti-flt-1 blocking antibody added to epithelioid SMC cultures reduced serum-deprived apoptosis and migration but not PDGF-BB-induced proliferation, and increased cell-populated collagen lattice contraction. In conclusion, vascular SMC stem marker expression was variable, chronologically modulated and prevalent in epithelioid populations and clones; among stem markers, flt-1 expression critically regulates intimal SMC response to microenviromental changes.
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PMID:Stem cell marker expression and proliferation and apoptosis of vascular smooth muscle cells. 1909 24

Imatinib mesylate (STI571, Gleevec) is a signal transduction inhibitor and novel anti-cancer agent. It selectively inhibits aberrantly activated tyrosine kinases in malignant cells, for example, bcr-abl in leukaemia, platelet-derived growth factor receptor and stem cell factor receptor (c-Kit) in solid cancers including malignant glioma. However, recently published clinical studies with imatinib monotherapy in patients with malignant glioma demonstrated only very modest anti-tumour activity. The aim of this study was to investigate the biological activity of imatinib, its cellular mechanisms of action and its synergism with other chemotherapeutic agents in human malignant glioma cells in culture. Expression of PDGF/R and c-Kit was analyzed by RT-PCR. Proliferation was measured by MTT assays and drug synergy was assessed by the Chou-Talalay method. Cell cycle and apoptosis were analyzed by flow cytometry and migration by monolayer migration assays. Multi-immunoblot was performed on imatinib-treated and control malignant glioma cells. Results indicate that imatinib is more effective in inhibiting cell colony formation and migration rather than proliferation. Imatinib treatment caused cell cycle arrest of glioma cells in G0-G1 or G2/M, with significant elevation of a few cyclin-dependent kinases. Furthermore, imatinib acted synergistically with chemotherapy agents, such as the DNA alkylating agent, temozolomide, and riboneucleotide reductase inhibitors, for example, hydroxyurea at varied effective dose levels. In conclusion, imatinib exerts varied biological effects on malignant glioma cells in culture. Synergistic interaction of imatinib with chemotherapy agents may be related to cell cycle control mechanisms and could be potentially important in a clinical setting.
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PMID:Differential effect of imatinib and synergism of combination treatment with chemotherapeutic agents in malignant glioma cells. 1915 35

The tyrosine kinase (TK) inhibitor, imatinib, has revolutionized therapy of malignancies that are addicted to one of its target kinases, c-abl, c-kit and PDGF-R. This addiction is generally dependent on the acquisition of an activating kinase mutation, e.g., the bcr-abl fusion gene in chronic myeloid leukemia, or point mutations of KIT or PDGFRA in gastrointestinal stroma tumors (GIST). Other types of sarcomas are generally considered to be insensitive to imatinib. We have observed a striking and durable remission of an advanced angiosarcoma to imatinib that can only be explained by TK addiction. Unexpectedly, GIST-type KIT and PDGFRA mutations were absent in this case. This case illustrates the diagnostic challenges in identifying individual candidate patients for TK inhibitor therapy.
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PMID:Dramatic and durable efficacy of imatinib in an advanced angiosarcoma without detectable KIT and PDGFRA mutations. 1918 35

Restenosis, the re-occlusion of a diseased vessel following a surgical intervention, is a major cause of failure of angioplasty, stenting, and bypass grafting with natural and synthetic vessels. In healthy vessels, the endothelium exerts a control over smooth muscle cell (SMC) proliferation and migration. Unfortunately, revascularization procedures damage the endothelium of natural vessels and bypass vessels are completely devoid of endothelial cells. Many strategies have been developed to inhibit SMC proliferation and reduce intimal hyperplasia, yet most of the drugs tested thus far simultaneously inhibit endothelialization and do not selectively target SMCs. The ideal biological agent should have anti-proliferative effects on SMCs while preserving vascular healing and endothelialization so as to prevent late thrombosis. Imatinib mesylate is a specific inhibitor of three tyrosine kinase receptors, two of which, PDGF-R and c-Kit, are implicated in the pathogenesis of intimal hyperplasia. In this study, we investigated in vitro the potential of imatinib mesylate to inhibit SMCs and its effect on ECs. Our findings indicate that low doses of imatinib mesylate successfully inhibit SMC proliferation. Furthermore, at these concentrations, the drug was not only harmless to ECs, but also enhanced their proliferation. In light of these in vitro results, imatinib mesylate shows potential as a good candidate to inhibit intimal hyperplasia without delaying neo-endothelialization.
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PMID:On the ability of imatinib mesylate to inhibit smooth muscle cell proliferation without delaying endothelialization: an in vitro study. 1925 52

Gastrointestinal stromal tumor (GIST) is the most common form of sarcoma and can vary in size and clinical outcome from an incidental finding at the time of surgery to life-threatening metastatic disease. Surgery is the standard of care for primary disease, and the oral drug imatinib is the standard of care for metastatic disease. Sunitinib was approved in the United States in early 2006 for GIST refractory to imatinib. The pathology of GIST, surgical options for primary and metastatic disease, and findings leading to the use of imatinib and sunitinib for GIST are reviewed in this manuscript, with attention to the mutation statuses of c-kit and PDGF receptor that lead to imatinib sensitivity or resistance.
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PMID:Gastrointestinal Stromal Tumors (GIST) and Their Management. 1936 Jan 54

Imatinib, an orally administered tyrosine kinase inhibitor of PDGF receptor, c-abl and c-kit, is currently in clinical trials to assess its efficacy in malignant gliomas. Although imatinib does not readily penetrate an intact blood-brain barrier (BBB), the extent to which it distributes into regions of high grade gliomas where the BBB is compromised has not been determined. Patients with recurrent high-grade gliomas for whom repeat surgical tumor debulking was clinically indicated received imatinib mesylate 600 mg orally once a day for seven days prior to surgery. Tissue samples were collected from different regions of the tumor and the approximate location of these samples was determined using frameless stereotactic neuronavigation. Plasma samples were obtained immediately before and after the resection. The concentration of imatinib in the plasma and tumor samples was determined using high performance liquid chromatography with mass spectrometric detection. Eleven tumor samples were obtained from three patients with recurrent glioblastoma multiforme. The median concentration of imatinib in these 11 tumor specimens was 1.34 microg/g (range 0.21-4.31 microg/g) and the median tumor-to-plasma ratio was 0.71 (range 0.28-3.03). These findings suggest that imatinib can reach intratumoral concentrations similar to those or higher than in plasma in regions of glioblastoma where the BBB is disrupted as indicated by contrast enhancement on magnetic resonance imaging.
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PMID:Intratumoral concentrations of imatinib after oral administration in patients with glioblastoma multiforme. 1976 86

Sorafenib, a molecular-targeted agent that inhibits tumor cell proliferation and angiogenesis by inhibiting RAF serine-threonine kinase and VEGF, PDGF, Flt-3, c-Kit receptor tyrosine kinase, was approved in Europe and North America in 2007 and in Japan on May 20, 2009. In the 10 months since its approval, sorafenib has been prescribed for more than 3,700 patients with advanced hepatocellular carcinoma (HCC), and its efficacy has been confirmed in many cases. According to the consensus statements of the Japan Society of Hepatology in 2010, sorafenib is recommended for advanced HCC with extrahepatic spread or major vascular invasion such as invasion of the 1st branch of the portal vein or the main portal branch of the portal vein in patients with Child-Pugh A liver function. In addition to that, transcatheter arterial chemoembolization (TACE) or hepatic arterial infusion chemotherapy (HAIC) refractory HCC patients with Child-Pugh A liver function are also candidates of sorafenib monotherapy as a second-line treatment option. To date, 15 cases with complete remission (CR) to sorafenib in metastatic advanced HCC patients have been reported in Japan, an event that is rarely reported in other countries. Of the 90 cases treated by ourselves, 2 achieved CR. Factors indicating systemic cancer spread, including multiple liver lesions, lymph node metastases, adrenal metastases, lung metastases and vascular invasion, were completely absent in both cases of CR by 2 and 1 year, respectively. Similarly, three tumor markers (AFP, PIVKA-II, and AFP-L3) completely returned to normal values. Although cases of CR are rare, it seems that there might be racial differences in terms of gene mutations. Clinical trials for other molecular-targeted agents, including sunitinib, brivanib, or linifanib, are ongoing and their outcomes are eagerly awaited. According to a subanalysis of the SHARP study, it is expected that sorafenib in combination with resection, ablation, TACE or HAIC will markedly prolong the overall survival in early-, intermediate- and advanced- stage HCCs.
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PMID:Positioning of a molecular-targeted agent, sorafenib, in the treatment algorithm for hepatocellular carcinoma and implication of many complete remission cases in Japan. 2061 99


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