Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The stem cell factor/c-kit tyrosine kinase receptor pathway has been shown to be important for tumor growth and progression in several cancers, including mast cell diseases, gastrointestinal stromal tumor, acute myeloid leukemia, small cell lung carcinoma, and Ewing sarcoma. Studies using the oral agent STI-571 (Gleevec, Novartis), an inhibitor of the tyrosine kinases bcr-abl, c-kit, and PDGFR, have shown significant responses in patients with chronic myelogenous leukemia and gastrointestinal stromal tumor. With the aim of identifying additional groups of tumors that may use the stem cell factor/c-kit pathway and secondarily may be responsive to STI-571 treatment, this study surveyed 151 primary tumors from patients treated at St. Jude Children's Research Hospital for immunohistochemical expression of c-kit. Formalin-fixed, paraffin-embedded sections were stained with rabbit polyclonal anti-human c-kit (CD117, Dako) using standard avidin-biotin-peroxidase complex technique, antigen retrieval, and an automated stainer. Strong, diffuse staining for c-kit was seen in a proportion of synovial sarcomas, osteosarcomas, and Ewing sarcomas. Strong, diffuse staining was less common in neuroblastomas, Wilms' tumors, and rhabdomyosarcomas and was negative in alveolar soft part sarcomas and desmoplastic small round cell tumors. Tumors with strong, diffuse staining for c-kit in a pattern similar to gastrointestinal stromal tumor may represent suitable targets for new therapeutic agents.
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PMID:C-kit expression in pediatric solid tumors: a comparative immunohistochemical study. 1191 27

Clonal cytogenetic abnormalities similar to those observed in other haematological neoplasms are demonstrable in a proportion of patients with systemic mastocytosis and in a smaller proportion of adults with urticaria pigmentosa without apparent systemic disease. These clonal abnormalities are not likely to represent the primary event in mast cell neoplasms. Although no recurrent cytogenetic abnormalities specific for mastocytosis have yet been recognized, the majority of cases display one of several mutations in c-KIT, the gene encoding the receptor for stem cell factor. That most commonly observed is the Asp816Val mutation, which permits proliferation independent of growth factors. c-KIT mutations may play a significant role in the biology of mast cell malignancies, although other mutations may be needed for a malignant phenotype.
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PMID:Cytogenetic and molecular genetic abnormalities in systemic mastocytosis. 1191 94

Human testicular germ cell tumours of adolescents and adults (TGCTs), including their precursor lesion carcinoma in situ (CIS), show expression of a 1.5 kb alternative transcript of the platelet-derived growth factor (PDGF) alpha-receptor gene. The so-called P2 promoter involved is located in intron 12 and its activity was found to be mutually exclusive with activity of the classical promoter (P1), which encodes the full-length receptor. The presence of the 1.5 kb transcript could be a putative marker for the early molecular diagnosis of TGCTs. In order to validate the RT-PCR approach, this study shows that not more than 100 transcripts are necessary to obtain positivity in the test used; moreover, samples from TGCTs or CIS-containing tissues can be diluted many-fold before resulting in false-negative findings. This study also shows that within TGCTs, as in TGCT-derived cell lines, expression of the 1.5 kb transcript is differentiation-dependent and positively correlated with expression of the embryonic transcription factor OCT-4/POU5F1. Furthermore, the results indicate that in some non-TGCT cancers and cell lines the 1.5 kb transcript is also expressed, but without concomitant OCT-4/POU5F1 expression. The 1.5 kb transcript is also present in early B cells and derived leukaemias (B-ALL). In spite of similarities in chromosomal location, down-regulation upon differentiation of TGCTs, and PDGF alpha-receptor and c-KIT (the stem cell factor receptor) both being a tyrosine kinase receptor, no correlation was found between activity of the P2 promoter of the PDGF alpha-receptor gene and expression of c-KIT. In conclusion, the 1.5 kb transcript of the PDGF alpha-receptor is expressed in various cells and tissues, including particular blood cells. Although this may hamper the use of this transcript as a marker for malignancies in general, it does not appear to interfere with assays for the early detection of TGCTs.
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PMID:Expression of the PDGF alpha-receptor 1.5 kb transcript, OCT-4, and c-KIT in human normal and malignant tissues. Implications for the early diagnosis of testicular germ cell tumours and for our understanding of regulatory mechanisms. 1192 Jul 44

We identified a novel erythropoietin (Epo)-induced protein (CIP29) in lysates of human UT-7/Epo leukemia cells using two-dimensional gel analysis and cloned its full-length cDNA. CIP29 contains 210 amino acids with a predicted MW of 24 kDa, and has a N-terminal SAP DNA-binding motif. CIP29 expression was higher in cancer and fetal tissues than in normal adult tissues. CIP29 mRNA expression is cytokine regulated in hematopoietic cells, being up-regulated by Epo in UT7/Epo cells, and by thrombopoietin (Tpo), FLT3 ligand (FL) and stem cell factor (SCF) in primary human CD34(+) cells. Up-regulation of CIP29 in UT7/Epo cells by Epo was associated with cell cycle progression but not with antiapoptosis. Epo withdrawal reduced CIP29 expression concomitant with cell cycle arrest. Overexpression of CIP29-GFP in HEK293 cells enhances cell cycle progression. CIP29 appears to be a new cytokine regulated protein involved in normal and cancer cell proliferation.
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PMID:Cloning and characterization of a proliferation-associated cytokine-inducible protein, CIP29. 1192 8

Stem cell factor (SCF) is essential to the migration and differentiation of melanocytes during embryogenesis because mutations in either the SCF gene, or its ligand, KIT, result in defects in coat pigmentation in mice. Using a neural crest cell (NCC) primary culture system from wild-type mice, we previously demonstrated that KIT-positive and/or L-3, 4-dihydroxyphenylalanine (DOPA)-positive melanocyte precursors proliferate following the addition of SCF to the culture medium. Extracellular matrix (ECM) proteins are considered to play a role in the migration and differentiation of various cells including melanocytes. We cultured mouse NCCs in the presence of SCF in individual wells coated with ECM; fibronectin (FN), collagen I (CLI), chondroitin sulphate, or dermatan sulphate. More KIT-positive cells and DOPA-positive cells were detected in the presence of SCF on ECM-coated wells than on non-coated wells. A statistically significant increase in DOPA-positive cells was evident in FN and CLI wells. In contrast, in the absence of SCF, few DOPA-positive cells and KIT-positive cells were detected on either the ECM-coated or non-coated wells. We concluded that ECM affect melanocyte proliferation and development in the presence of SCF. To determine the key site of FN function, RGDS peptides in the FN sequence, which supports spreading of NCCs, were added to the NCC culture. The number of DOPA-positive cells decreased with RGDS concentration in a dose-dependent fashion. Immunohistochemical staining revealed the presence of integrin alpha5, a receptor of RGDS, in NCCs. These results suggest the RGDS domain of FN plays a contributory role as an active site in the induction of FN function in NCCs. In addition, we examined the effect of FN with SCF on the NCC migration by measuring cluster size, and found an increase in size following treatment with FN.
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PMID:Fibronectin combined with stem cell factor plays an important role in melanocyte proliferation, differentiation and migration in cultured mouse neural crest cells. 1202 83

Mast cells (MCs) are multifunctional hematopoietic effector cells that produce and release an array of biologically active mediator substances. Growth and functions of MCs are regulated by cytokines, other extracellular factors, surface and cytoplasmic receptors, oncogene products, and a complex network of signal transduction cascades. Key regulators of differentiation of MCs appear to be stem cell factor (SCF) and its tyrosine kinase receptor KIT (c-kit proto-oncogene product=CD117), downstream-acting elements, and the mi transcription factor (MITF). Signaling through KIT is negatively regulated by the signal regulatory protein (SIRP)-alpha (CD172a)-SHP-1-pathway that is disrupted in neoplastic MCs in MC proliferative disorders. Both KIT and FcepsilonRI are involved in MC activation and mediator release. Activation of MCs through FcepsilonRI is associated with increased expression of activation-linked membrane antigens as well as with signaling events involving Lyn and Syk kinases, the phosphatidylinositol-3-kinase-pathway, Ras pathway, and the phospholipase C-protein kinase C pathway. A similar network of signaling is found in SCF-activated MCs. The current article gives an overview on signal transduction-associated and activation-linked antigens expressed in human MCs. Wherever possible the functional implication of signaling pathways and antigen expression are discussed.
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PMID:Signal transduction-associated and cell activation-linked antigens expressed in human mast cells. 1204 64

Mutations in the proto-oncogene c-kit, including point mutations, deletions, or duplications in the negative regulatory juxtamembrane (JM) domain or point mutations in the catalytic domain, have been observed in human and canine cancers and often result in constitutive activation of Kit in the absence of ligand binding. To identify a receptor tyrosine kinase (RTK) inhibitor capable of blocking the function of mutant Kit, we evaluated 3 indolinones (SU11652, SU11654, and SU11655) that act as competitive inhibitors of adenosine triphosphate binding to several members of the split kinase family of RTKs, including VEGFR, FGFR, PDGFR, and Kit. Mast cell lines expressing either wild-type (WT) Kit, a point mutation in the JM domain, a tandem duplication in the JM domain, or a point mutation in the catalytic domain were used for these studies. All 3 indolinones inhibited phosphorylation of WT Kit in the presence of stem cell factor at concentrations as low as 0.01 microM. Autophosphorylation of both JM mutants was inhibited at 0.01 to 0.1 microM, resulting in cell cycle arrest within 24 hours, whereas autophosphorylation of the catalytic domain mutant was inhibited at 0.25 to 0.5 microM, resulting in cell death within 24 hours. poly(ADP-ribose) polymerase (PARP) cleavage was noted in all Kit mutant lines after indolinone treatment. In summary, SU11652, SU11654, and SU11655 are effective RTK inhibitors capable of disrupting the function of all forms of mutant Kit. Because the concentrations of drug necessary for receptor inhibition are readily achievable and nontoxic in vivo, these compounds may be useful in the treatment of spontaneous cancers expressing Kit mutations.
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PMID:Inhibition of constitutively active forms of mutant kit by multitargeted indolinone tyrosine kinase inhibitors. 1209 52

Two alternatively spliced stem cell factor (SCF) transcripts encode protein products, which differ in the duration of membrane presentation. One form, soluble SCF (S-SCF) gets rapidly processed to yield predominantly secreted protein. The other form, membrane-associated SCF (MA-SCF) lacks the primary proteolytic cleavage site but is cleaved slowly from an alternate site, and thus represents a more stable membrane form of SCF. Mutants of SCF that lack the expression of MA-SCF (Steel-dickie) or possess a defect in its presentation (Steel(17H)) manifest deficiencies in erythroid cell development. In this study, we have compared the consequence(s) of activating Kit, the receptor for SCF by MA-SCF with S-SCF, and an obligate membrane-restricted (MR) form of SCF (MR-SCF) on erythroid cell survival, proliferation, cell cycle progression, and the activation of p38 and ERK MAP kinase pathways. Activation of Kit by MR-SCF was associated with a significantly lower incidence of apoptosis and cell death in erythroid cells compared to either other isoform. MR- or MA-SCF-induced stimulation of erythroid cells resulted in similar and significantly greater proliferation and cell cycle progression compared to soluble SCF. The increase in proliferation and cell cycle progression via MA- or MR-SCF stimulation correlated with sustained and enhanced activation of p38 and ERK MAP kinase pathways. In addition, MR- or MA-SCF-induced proliferation was more sensitive to the inhibitory effects of ERK inhibitor compared to S-SCF-induced proliferation. In contrast, soluble SCF-induced proliferation was more sensitive to the inhibitory effects of p38 inhibitor compared with MR- or MA-SCF. These results suggest that different isoforms of SCF may use different biochemical pathways in stimulation of survival and/or proliferation of erythroid cells.
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PMID:Role of p38 and ERK MAP kinase in proliferation of erythroid progenitors in response to stimulation by soluble and membrane isoforms of stem cell factor. 1214 9

Recovery from radiation-induced (RI) myelosuppression depends on hematopoietic stem and progenitor cell survival and the active proliferation/differentiation process, which requires early cytokine support. Single cytokine or late-acting growth factor therapy has proved to be inefficient in ensuring reconstitution after severe RI damage. This work was aimed at evaluating the in vivo survival effect of combinations of early-acting cytokines whose antiapoptotic activity has been demonstrated in vitro: stem cell factor (SCF [S]), FMS-like tyrosine kinase 3 ligand (FLT-3 ligand [F]), thrombopoietin (TPO [T]), interleukin-3 (IL-3 [3]), and stromal derived factor-1 (SDF-1). B6D2F1 mice underwent total body irradiation at 8 Gy cesium Cs 137 gamma radiation (ie, lethal dose 90% at 30 days) and were treated soon after irradiation, at 2 hours and at 24 hours, with recombinant murine cytokines, each given intraperitoneally at 50 microg/kg per injection. All treatments induced 30-day survival rates significantly higher than control (survival rate, 8.3%). 4F (SFT3) and 5F (4F + SDF-1) were the most efficient combinations (81.2% and 87.5%, respectively), which was better than 3F (SFT, 50%), TPO alone (58.3%), and SDF-1 alone (29.2%) and also better than 4F given at 10 microg/kg per injection (4F10, 45.8%) or as a 50 microg/kg single injection at 2 hours (4Fs, 62.5%). Despite delayed death occurring mainly from day 150 on and possible long-term hematopoiesis impairment, half the 30-day protective effects of 4F and 5F were preserved at 300 days. Our results show that short- and long-term survival after irradiation depends on appropriate multiple cytokine combinations and at optimal concentrations. The proposal is made that an emergency cytokine regimen could be applied to nuclear accident victims as part of longer cytokine treatment, cell therapy, or both.
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PMID:Short-term injection of antiapoptotic cytokine combinations soon after lethal gamma -irradiation promotes survival. 1246 35

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.
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PMID:Juxtamembrane mutant V560GKit is more sensitive to Imatinib (STI571) compared with wild-type c-kit whereas the kinase domain mutant D816VKit is resistant. 2207 14


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