Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0027627 (metastases)
 103,950 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mice carrying mutations at the Sl (steel) and W (dominant white spotting) loci develop abnormalities on 3 migratory embryonic stem cell populations: hematopoietic stem cells, neural crest-derived melanocytes, and primordial germ cells. Transplantation experiments have indicated that the Sl locus affects the microenvironment where stem cells migrate, proliferate, and differentiate, while the W locus affects the migratory cells themselves. The Sl locus encodes for a multipotent growth factor known as stem cell factor. The W locus encodes the c-kit protein tyrosine kinase receptor whose ligand is the stem cell factor. We have investigated the incidence and organ distribution of experimental metastases after systemic intra-arterial injection of B16-G3.26 melanoma cells into mutant Sl/Sld and W/Wv mice. Both mutant mouse strains had a markedly lower incidence of ovarian metastases when compared with their congenic +/+ mice. In contrast to the rare colonization of the ovaries, Sl/Sld and W/Wv mice developed metastases in the myocardium, kidney, and stomach--anatomic sites that were infrequently or never affected in their congenic nonmutant mice. The only organs in which the average number of metastatic colonies differed between Sl/Sld and W/Wv mice were the bone marrow and kidneys. The average number of colonized bones per mouse in the Sl/Sld group was 5.0 +/- 3.1 (SD), compared with 12.7 +/- 5.3 in the W/Wv group. The average number of metastatic nodules in the kidneys of Sl/Sld mice was 24.6 +/- 9, while W/Wv mice had 15.5 +/- 2.5. Mutant mice with multiple metastatic nodules in the kidneys, heart, and stomach were also found to have forestomach papillomas, an enlarged duodenum, kidney abnormalities, and small body size. The results of this study provide useful information on potential mechanisms of interaction of metastatic cells with their target organs, and suggest that there are additional organ defects associated with the mutations in the Sl and W loci. They also document the importance of mutant mice in metastasis research.
 ...
PMID:Incidence and distribution of experimental metastases in mutant mice with defective organ microenvironments (genotypes Sl/Sld and W/Wv). 155 33

Metastasis in children with neuroblastoma (NB) is a poor prognostic factor despite intensive therapy. In the near future, stem cell factor (SCF) is likely to be used clinically to accelerate bone marrow (BM) recovery after high-dose chemotherapy in patients with advanced NB. The high frequency of BM metastases in NB could be secondary to BM-derived human growth factors (HGF) modulating the adhesion, secondary growth (or both) of circulating metastatic NB cells. To test this hypothesis, we studied the in vitro effects on NB cell lines grown in chemically defined medium of SCF, interleukin (IL)-1 beta, IL-3, IL-6, basic fibroblast growth factor (bFGF), transforming growth factor-beta (TGF-beta) used alone or in combination. The antigenic expression of NB-associated cell adhesion molecules (CAM) HLA class 1, intercellular CAM-1, neural-CAM and CD44 were assayed by monoclonal antibodies and flow cytometry, and DNA synthesis by 3H-thymidine uptake. The expression of CAM was not modulated by SCF or other HGFs. An increase in thymidine uptake was induced by bFGF alone in IMR-32 cells, while SCF and other HGFs had no notable effect. Our results indicate that SCF and other BM-derived HGFs are unlikely to have a generalised effect on the expression of adhesion molecules by NB cells or proliferation. The clinical administration of recombinant human SCF to children with NB should be safe.
 ...
PMID:Effects of stem cell factor and other bone marrow-derived growth factors on the expression of adhesion molecules and proliferation of human neuroblastoma cells. 757 47

Stem cell factor receptor (SCFR, c-kit), normally expressed on haematopoietic and mast cells, plays a regulatory role in cellular growth and differentiation. Dysregulated expression of SCFR may contribute to neoplastic transformation. We investigated expression of SCFR on malignant canine mast cells obtained directly from spontaneous canine mast cell neoplasms, in an attempt to determine whether these undifferentiated cells maintained expression of this growth-promoting cytokine receptor. Malignant mast cells (histological grade 2) from skin tumours or lymph node metastases were collected from canine patients, and SCFRs were detected by flow cytometric analysis of these cells. All of the tumours bound mouse and canine recombinant stem cell factor (SCF), indicating that the cells not only expressed SCFRs, but that the receptors possessed the functional property of ligand binding. Immunoglobulin Fc receptors for canine IgE were identified on these cells by flow cytometry, a further indication that the cells analysed were mast cells and retained some differentiated features. Immunohistochemical analysis of formalin-fixed, paraffin wax-embedded mast cell tumour biopsies confirmed expression of SCFRs by malignant cells from each tumour. The relative binding of SCF to suspensions of tumour cells, as assessed by flow cytometry, correlated with the intensity of immunolabelling for SCFR in sections of the same tumours, suggesting variability in SCFR expression between tumours. Agarose gel electrophoresis of the products of SCFR reverse transcription-polymerase chain reaction derived from each tumour had the molecular weight predicted for canine SCFR cDNA on the basis of the mouse and human counterparts. This further confirmed SCFR expression by malignant canine mast cells. Taken together, these results show that a membrane receptor capable of triggering cell growth is expressed by malignant canine mast cells, suggesting a role for this receptor in the aetiology of canine mast cell cancer. This relatively common malignancy of the dog would seem to present an opportunity for the investigation of the potential role of the SCF/SCFR pathway in the development of spontaneous malignancies of mast cells.
 ...
PMID:Expression of stem cell factor receptor (c-kit) by the malignant mast cells from spontaneous canine mast cell tumours. 900 81

Melanoma cells in culture express a variety of growth factors and cytokines and some of their autocrine and paracrine roles have been investigated. However, less information is available on the potential dynamic changes in expression of these molecules on cells during melanoma development and progression in situ. Using immunohistochemistry, we tested 40 nevi and primary and metastatic melanoma lesions for the expression of 10 growth factors and cytokines and the respective receptors representing 10 cell surface molecules. Nevi and thin (< 1 mm) primary melanomas showed little expression of ligands except weak reactivity of tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta), interleukin-8 (IL-8) and reactivity of TGF-betaR and c-kit. Marked up-regulation of growth factors, cytokines and receptor expression was observed in thick (> 1 mm) primary melanomas, which were stained with polyclonal or monoclonal antibodies (MAbs) for IL-1alpha, IL-1beta, IL-6, IL-8, TNF-alpha, TGF-beta, granulocyte-macrophage colony-stimulating factor (GMCSF) and stem cell factor (SCF), but not IL-2. Metastases showed similar expression patterns except that SCF was absent. Co-expression of ligand and receptor was observed for TGF-beta, GM-CSF and IL-6, suggesting an autocrine role for these ligands. TNF-alpha appears to be a marker of benign lesions; IL-6 and IL-8 expression is associated with biologically early malignancy; TGF-beta, GM-CSF and IL-1alpha are highly expressed in biologically late lesions; and TNF-beta is an apparent marker of metastatic dissemination. Our results indicate that melanoma cells utilize cascades of growth factors and cytokines for their progression.
 ...
PMID:Immunohistochemical evidence of cytokine networks during progression of human melanocytic lesions. 1009 49

Stem cell factor (SCF), the ligand for c-Kit, is known to regulate developmental and functional processes of haematopoietic stem cells, mast cells and melanocytes. Two different splice variants form predominantly soluble (sSCF or SCF-1) and in addition some membrane-bound SCF (mSCF or SCF-2). In order to explore the prognostic significance of these molecules in melanoma, total SCF, SCF splice variants and c-Kit expression were studied in normal skin melanocytes and in 11 different melanoma cell lines, using reverse transcription polymerase chain reaction, immunocytochemistry and enzyme-linked immunosorbent assay. Nine of the 11 melanoma cell lines expressed SCF-1 mRNA, only two of them SCF-2, and these two also SCF-1. Coexpression of both SCF-1 and c-Kit was noted in five cell lines, and only one cell line as well as normal melanocytes expressed both SCF-1 and SCF-2 as well as c-Kit. Corresponding results were obtained on immunocytochemical staining. Of three exemplary melanoma cell lines studied, two expressing SCF mRNA also released SCF spontaneously and on stimulation, whereas the line lacking SCF and c-kit mRNA (SK-Mel-23) failed to do so. These data demonstrate thus that melanoma cell lines, particularly those known to metastasize in vivo, lose the ability to express SCF-2 mRNA, suggesting that this molecule may serve, next to c-Kit, as a prognostic marker for malignant melanoma.
 ...
PMID:Expression of SCF splice variants in human melanocytes and melanoma cell lines: potential prognostic implications. 1078 May 26

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. The concept of GIST and the definition of GIST pathology have evolved greatly over the past 5 years. GIST has been shown to share immunohistochemical, ultrastructural and histogenic similarities with the interstitial cells of Cajal. Both GIST and the interstitial cells of Cajal express KIT, the receptor tyrosine kinase that is the protein product of the c-kit proto-oncogene. KIT is universally phosphorylated in GISTs. Sequencing of c-kit complementary DNA from human GIST cells has demonstrated a high frequency of mutations that lead to constitutive activation of the KIT tyrosine kinase in the absence of stimulation by its physiologic ligand (stem cell factor). This, in turn, causes uncontrolled stimulation of downstream signaling cascades with aberrant cellular proliferation and resistance to apoptosis. Historically, malignant GIST has been highly refractory to conventional cytotoxic therapy. Signal transduction inhibition as cancer therapy was first tested successfully with imatinib mesylate (formerly known as STI571), a selective small-molecule tyrosine kinase inhibitor, with the initial target being blockade of Bcr-Abl, the oncogene with tyrosine kinase activity responsible for the pathogenesis of chronic myelogenous leukemia (CML). Imatinib was subsequently shown to block activity of the KIT tyrosine kinase as well, and in laboratory studies this led to apoptotic death of GIST cells. The first GIST patient to receive imatinib exhibited dramatic benefit despite far-advanced metastatic disease that was previously refractory to all chemotherapy. Subsequently, multicenter clinical trials have been performed to assess the safety, efficacy and biologic activity of imatinib in patients with advanced GIST. The results from these studies have established imatinib as an effective new therapeutic alternative for the majority of patients with advanced GIST, a solid tumor for which no prior chemotherapy has ever shown antitumor efficacy. This work provides proof of concept to the hypothesis that selective inhibition of aberrant signal transduction can provide important anticancer activity, if the proper signaling pathways are identified and blocked.
 ...
PMID:Identification and treatment of chemoresistant inoperable or metastatic GIST: experience with the selective tyrosine kinase inhibitor imatinib mesylate (STI571). 1252 73

Imatinib mesylate (imatinib) is an orally administered competitive inhibitor of the tyrosine kinases associated with the KIT protein (stem cell factor receptor), ABL protein and platelet-derived growth factor receptors. The KIT tyrosine kinase is abnormally expressed in gastrointestinal stromal tumour (GIST), a rare neoplasm for which there has been no effective systemic therapy. In a randomised, nonblind, multicentre study that evaluated imatinib 400 or 600mg once daily in 147 patients with advanced GIST, confirmed partial responses were achieved in 54% of patients overall (median duration of follow-up was 288 days). Stable disease was experienced by 28% of patients and the estimated 1-year survival rate was 88%. Similar response rates were reported in a smaller, dose-escalation study, in which objective tumour response was a secondary endpoint. Although nearly all patients with GIST treated with imatinib experienced adverse events, most events were mild or moderate in nature. Severe or serious adverse events occurred in 21% of patients in the larger study, and included gastrointestinal or tumour haemorrhage. The control of cellular processes, such as cell growth, division and death, involves signal transduction, which commonly involves the transfer of phosphate from adenosine triphosphate (ATP) to tyrosine residues on substrate proteins, by tyrosine kinase enzymes. Activation of oncogenes coding for kinase proteins can lead to the production of kinases that are continually active in the absence of a normal stimulus,leading to increased cell proliferation and/or decreased apoptosis. A major focus of cancer research in recent years has been to identify oncogenic molecules and the signal transduction pathways in which they are involved, in order to develop specifically targeted drugs. One such drug is imatinib mesylate (imatinib, Glivic/Gleevec), an orally administered 2-phenylaminopyrimidine derivative that is a competitive inhibitor of the tyrosine kinases associated with platelet-derived growth factor (PDGF) receptors, the Abelson (ABL) protein and the KIT protein (also known as stem cell factor [SCF] receptor). Imatinib was initially evaluated for the treatment of chronic myeloid leukaemia (CML) [reviewed previously in Drugs]. More recently, imatinib has been approved for the treatment of patients with advanced gastrointestinal stromal tumour (GIST), in which KIT, a tyrosine kinase receptor, is abnormally expressed. GISTs are soft tissue gastrointestinal sarcomas probably arising from mesenchymal cells. They are rare neoplasms, with between 5000 and 10 000 new cases being diagnosed each year in the US. GISTs occur throughout the gastrointestinal tract but the stomach and small intestine are the most common sites. Symptoms depend on the site and size of the tumour, and may include abdominal pain, gastrointestinal bleeding or signs of obstruction; small tumours may be asymptomatic. The diagnosis of GIST is made by immunohistochemical staining for CD117, a cell surface antigen on the extracellular domain of KIT, in conjunction with pathological examination of tissue with light microscopy. All GISTs may have some degree of malignant potential. They are unresponsive to standard chemotherapy and to radiotherapy, and the mainstay of treatment in the past has been surgery. However, recurrence rates are high, and there has been no effective systemic treatment for unresectable GIST or metastatic disease. For patients in whom complete resection is not possible, or in patients with metastatic or recurrent disease, the median duration of survival is 9-12 months, and 10-19 months, respectively. Gain-of-function mutations of the KIT proto-oncogene occur in up to 90% of GISTs, allowing constitutive activation of tyrosine kinase (i.e. auto-phosphorylation of tyrosine residues independent of ligand-receptor binding), leading to aberrant cell division and tumour growth. Imatinib selectively inhibits the tyrosine kinase activity associated with KIT, which forms the rationale for evaluating its effects in GIST. Subsequent to initial evidence of the clinical efficacy of imatinib in a single patient with progressive, metastatic, CD117-positive GIST, formal studies of imatinib in this new indication were initiated. This article summarises the pharmacology, efficacy and tolerability profile of imatinib in the treatment of patients with advanced GIST.
 ...
PMID:Imatinib mesylate: in the treatment of gastrointestinal stromal tumours. 1260 Feb 28

Lung cancer accounts for approximately 30% of all cancer mortalities in the United States. Small cell lung cancer (SCLC), which is an aggressive malignancy with frequent and early metastases, accounts for about 15% of all of the lung cancer cases with a dismal 5-year survival rate of < 5% with current standard therapies. Early detection of SCLC is challenging, in part due to the lack of adequate serum tumor markers. The goal of this review is to summarize the current knowledge of circulating tumor cells and serum biomarkers in small cell lung cancer. The role of circulating tumor cells in prognostication is controversial, but may be better defined with advancing technologies of detection of such cells with higher precision, and improved clinico-pathological correlations. The current knowledge on the known serum cytokines and tumor biomarkers of SCLC, such as CEA, chromogranin-A and neuron-specific enolase will be presented. Serum cytokines, such as vascular endothelial growth factor (VEGF), stem cell factor (SCF) and hepatocyte growth factor/scatter factor (HGF/SF) are also discussed. New findings in the search for novel diagnostic and therapeutic molecular markers using the emerging genomics and proteomics technologies are emphasized. It is our hope that validation of these new research platforms and technologies will result in improved early detection, prognostication and finally treatment of SCLC with potential novel molecularly-targeted therapeutics.
 ...
PMID:Circulating tumor cells and serum tumor biomarkers in small cell lung cancer. 1268 52

The Kit receptor tyrosine kinase is a transmembrane receptor that is expressed in a variety of different tissues and mediates pleiotropic biological effects through its ligand stem cell factor (SCF). Sporadic mutations of Kit as well as autocrine/paracrine activation mechanisms of the SCF/Kit pathway have been implicated in a variety of malignancies, where its primary contribution to metastases is in enhancing tumor growth and reducing apoptosis. For example, Kit is frequently mutated and activated in gastrointestinal stromal tumors (GISTs) and there is ligand-mediated activation of Kit in some lung cancers. Kit is a convenient target in Kit-induced tumors and inhibition of this receptor with the small molecule drug Gleevec (imatinib mesylate, STI571) in GIST has shown dramatic efficacy. Unfortunately, past experience has demonstrated that chemotherapy of cancers with a single drug often leads to resistance of the cancer. Further understanding of the molecular mechanisms underlying Kit-mediated transformation is therefore important and may lead to the identification of further novel drug targets. These Kit-specific signaling pathways may then be targeted to overcome potential drug resistance. This review will focus on our understanding of the molecular mechanisms involved in transformation by Kit. The potential mechanisms by which Kit induces cellular transformation are described. We will also discuss the role and expression of Kit in various malignancies. Ultimately, the understanding of c-Kit biology, biochemistry, and mutational analysis will lead to better therapeutics.
 ...
PMID:Targeting c-Kit mutations: basic science to novel therapies. 1503 37

Stem cell factor (SCF), next to various relevant biological effects exerted on many cell types, is able to keep melanocyte homeostasis through its receptor c-kit. Only a minority of metastatic melanoma cells (MMC) express c-kit receptor, but c-kit positive MMC move more slowly towards tumour progression and have a more natural tendency to undergo apoptosis. In our study c-kit positive MMC from human melanoma metastases and a c-kit positive human melanoma cell line-SK-MEL-28-showed a clear-cut reduction of cytokines normally up-regulated along melanoma progression after SCF stimulation. SCF was also able to maintain all MMC and SK-MEL-28 cells in a well differentiated status with an increase in organellogenesis and in particular of melanosomes in various degree of differentiation, but it did not induce apoptosis as observed in other in vitro models. The increase of melanosomes matched an increase of tyrosinase production. SCF did not modify the expression of NOS while it enhanced the expression of HLA-DR molecules on MMC membranes. Taken altogether these data stress the biological activity of SCF as a cytokine which is able to maintain MMC in a well differentiated status, and suggest a more in depth evaluation of possible effects of SCF on melanoma cells.
Clin Exp Metastasis 2006
PMID:Stem cell factor affects tumour progression markers in metastatic melanoma cells. 1702 24


1 2 3 Next >>