Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C1261473 (sarcoma)
 25,952 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Gastrointestinal stromal tumors (GISTs) are non differentiated sarcoma of the gastrointestinal tract and have for a long time been confused with well differentiated tumors and classified as leiomyosarcoma. These tumors are characterized immunohistochemically by CD 117 staining. This marker represents the expression of c-kit which is a receptor for growth factor with enzymatic activity (tyrosine kinase). Recent studies have found that an inhibitor of specific tyrosine kinase is effective in the treatment of GIST with an estimated response rate of more than 60%. This new drug could significantly improve the prognosis of these aggressive chemoresistant tumors.
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PMID:[At last, an effective therapy for non-differentiated GI sarcomas (gastro intestinal stromal tumor)]. 1241 Jan 26

Low molecular weight protein tyrosine phosphatases (LMW-PTPs) are an enzyme family that plays a key role in cell proliferation control by dephosphorylating/inactivating both tyrosine kinase receptors (such as PDGF, insulin, and ephrin receptors) and docking proteins (such, as beta-catenin) endowed with both adhesion and transcriptional activity. Besides being a frequent event in human tumors, overexpression of LMW-PTP has been recently demonstrated to be sufficient to induce neoplastic transformation. We recently demonstrated that overexpression of LMW-PTP strongly potentiates the stability of cell-cell contacts at the adherens junction level, which powerfully suggests that LMW-PTP may also contribute to cancer invasivity. Focusing on mechanisms by which LMW-PTP is involved in cancer onset and progression, the emerging picture is that LMW-PTP strongly increases fibronectin-mediated cell adhesion and mobility but, paradoxically, decreases cell proliferation. Nevertheless, LMW-PTP-transfected NIH3T3 fibroblasts engrafted in nude mice induce the onset of larger fibrosarcomas, which are endowed with higher proliferation activity as compared to mock-transfected controls. Quite opposite effects have been obtained with engrafted fibroblasts transfected with a dominant-negative form of LMW-PTP. Notably, in sarcoma extracts, LMW-PTP overexpression greatly influences the ephrin A2 (EphA2) but not PDGF receptor or beta-catenin tyrosine phosphorylation. The high association of dephosphorylated EphA2 overexpression with most human cancers and our observation that cell growth stimulation by LMW-PTP overexpression is restricted to the in vivo model, strongly suggest that LMW-PTP oncogenic potential is mediated by its EphA2 tyrosine dephosphorylating activity.
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PMID:LMW-PTP is a positive regulator of tumor onset and growth. 1502

The management of soft tissue sarcomas has been highlighted in the last few years by the responsiveness of gastrointestinal stromal tumors to imatinib (Gleevec, Novartis). In this article, the use of chemotherapeutic agents in the management of this and some of the 50 or more subtypes of sarcomas are discussed, and a brief review of the use of chemotherapy in the adjuvant or neoadjuvant setting for people with large extremity sarcomas is provided. Doxorubicin and ifosfamide (Mitoxana, Bristol-Myers Squibb) remain the best individual drugs for sarcomas overall, although dacarbazine and gemcitabine (Gemzar, Eli Lilly) with or without a taxane has activity in at least a subset of sarcomas. The data regarding adjuvant chemotherapy for extremity soft tissue sarcomas is still quite mixed, with little if any overall survival advantage found to support its incorporation into disease management. The finding of tyrosine kinase inhibitors such as imatinib with demonstrated activity in gastrointestinal stromal tumors and dermatofibrosarcoma protuberans, as well as the finding of new agents such as ecteinascidin-743 (Yondelis, PharmaMar) with at least some activity against soft tissue sarcomas, reinforces the idea that we should target individual subtypes of sarcoma, just as treatment varies by subtype for the hematological malignancies.
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PMID:Role of chemotherapy in patients with soft tissue sarcomas. 1505 53

Feline vaccine-associated sarcoma (VAS) is a biologically aggressive soft-tissue sarcoma that can develop at sites where inactivated feline vaccines have been administered. We showed that platelet-derived growth factor (PDGF) and its receptor (PDGFR) play a role in the growth of VAS cells. The presence of PDGFR-beta was confirmed in each of five VAS cell lines evaluated, one non-vaccine-associated feline fibrosarcoma (FSA) cell line and a feline fibroblast-derived cell line. The PDGF/PDGFR signaling pathway was inhibited in the VAS cell lines and the FSA cell line using the tyrosine kinase inhibitor imatinib mesylate (formerly called STI-571). Imatinib inhibited PDGF-BB-induced autophosphorylation of PDGFR in VAS cells and feline FSA cells in vitro in a dose-dependent manner. Imatinib also significantly inhibited growth of feline VAS tumors in a murine xenograft model. Imatinib reversed the protective effect of PDGF-BB on growth inhibition by doxorubicin and carboplatin. PDGF-BB protected VAS cells from serum starvation and doxorubicin-induced apoptosis but not carboplatin-induced apoptosis, and imatinib eliminated this protection. These observations suggest that imatinib inhibits PDGFR tyrosine kinase activity in feline soft tissue sarcomas in vitro and inhibits tumor growth in a xenograft model.
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PMID:Imatinib mesylate inhibits platelet-derived growth factor activity and increases chemosensitivity in feline vaccine-associated sarcoma. 1510 21

Myxoid/round cell liposarcomas (MLS/RCLS) are characterized by chromosome translocations that result in formation of FUS-CHOP or EWSR1-CHOP fusion oncogenes. More than 95% of the tumors carry one of these fusion genes. FUS-CHOP transforms 3T3 cells and causes MLS/RCLS-like tumors in transgenic mice. The fusion oncoproteins act as abnormal transcription factors and are believed to induce abnormal expression of growth controlling genes as part of their transforming activities. The aim of this study was to search for recurrent abnormal expression patterns of cell cycle regulating proteins and growth factor receptors. A series of 14 MLS/RCLS, 2 MLS/RCLS derived cell lines and a FUS-CHOP transfected human sarcoma cell line were analyzed using immunohistochemistry, Western blotting, and cDNA microarray based screening. The results revealed a highly abnormal expression pattern of several growth controlling proteins. The G1 cyclins D1 and E and their associated kinases CDK4 and CDK2 were strongly overexpressed in all of the tumors. High expression levels were also found for Cdk4/6 inhibitor P16 and CDK2 inhibitors P27 and P57. The growth factor tyrosine kinase receptors PDGFRB and EGFR were present in most cells of all investigated tumors. We conclude that deregulation of G1 controlling proteins is common in MLS/RCLS and that aberrant expression of these proteins is of importance in the pathogenesis of this tumor type.
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PMID:Abnormal expression of cell cycle regulators in FUS-CHOP carrying liposarcomas. 1549 25

A specific treatment for gastrointestinal stromal tumors (GIST) has been found through improved understanding of the molecular mechanism of carcinogenesis. GIST are radio and chemo-resistant (less than 10 objective responses). Stromal tumors originate from the multiplication of the cells of Cajal, which intervene in intestinal motility and express the c-Kit gene, also called CD117, on their surface. CD117 is a protein with tyrosine kinase activity, and can be demonstrated through immunohistochemical staining techniques. Treatment with Imatinib mesylate (Glivec), a recently discovered selective inhibitor of tyrosine kinases already used in chronic myeloid leukemia (in which an overexpression of tyrosine kinase is observed) was associated with tumor regression of more than 50% in the initial series of patients with GIST treated in 2001. Since then, approximately 2,000 patients have been included in therapeutic trials, with an objective response rate between 60% and 70% 12 to 18 months after inclusion. The clinical benefit has been estimated at 80% to 90% in patients whose chance of survival until now has been less than 30% at one year (median survival 18 months). Nonetheless, imatinib mesylate has not shown any activity in CD117-negative sarcoma (10% of sarcoma). The therapeutic importance of this drug in the treatment of solid GI tumors deemed inoperable is considerable.
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PMID:Treatment of gastrointestinal stromal tumors with imatinib mesylate: a major breakthrough in the understanding of tumor-specific molecular characteristics. 1570 44

Among gynecologic malignancies, ovarian carcinoma is the most frequent cause of death, with the majority of patients presenting at advanced stage. There is a high rate of recurrence despite first-line chemotherapy. Sarcoma of the uterus, while accounting for a small percent of uterine cancers, is also associated with a high-recurrence rate and poor overall survival. Therefore, the development of novel treatment strategies is paramount. Imatinib mesylate (Gleevec; Novartis Pharmaceuticals Corp., East Hanover, NJ) is a tyrosine kinase inhibitor with activity against abl, c-kit, and platelet derived growth factor receptor (PDGFR), and is approved for the treatment of chronic myelogenous leukemia and gastrointestinal stromal tumor. Preclinical data provides evidence for c-kit and PDGFR expression in ovarian epithelial carcinomas and uterine sarcomas and have led to clinical trials evaluating the use of imatinib in these malignancies. Additionally, inhibition of PDGFR signaling has been proposed as an effective mechanism of chemotherapy by lowering tumor interstitial fluid pressure. Recent data have also suggested benefit with metronomic scheduling of cytotoxic agents at lower doses at more frequent dosing intervals, in combination with other targeted therapies. While activity of this agent remains to be established, further studies of imatinib in gynecologic malignancies are warranted, to demonstrate not only single-agent activity and the enhancement of cytotoxicity of other antineoplastic agents.
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PMID:Imatinib mesylate and its potential implications for gynecologic cancers. 1571 93

This presentation describes the events that led to the sequential discoveries of nerve growth factor (NGF) and epidermal growth factor (EGF). Each was isolated during attempts to understand the biochemical basis for unexpected biological observations. The in vivo stimulation of the growth of specific nerve fibers following the transplantation of a mouse sarcoma into a chick embryo eventually resulted in the finding of NGF, not only in the transplanted tumor but also in snake venom and in the mouse salivary gland. Unexpectedly, treatment of newborn animals with extracts of the mouse salivary gland resulted not only in enhancement of nerve growth but also in precocious eyelid opening and tooth eruption. The latter observations led to the isolation of both EGF and its tyrosine kinase-active receptor.
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PMID:Origins of growth factors: NGF and EGF. 1583 3

Imatinib mesylate is a tyrosine kinase inhibitor of the ABL, platelet-derived growth factor receptor (PDGFR), and c-kit kinases. Inhibition of BCR-ABL and c-kit accounts for its clinical activity in leukemia and sarcoma, respectively. In this report, we describe other cellular targets for imatinib. Treatment of head and neck squamous carcinoma cells with clinically relevant concentrations of imatinib-induced changes in cell morphology and growth similar to changes associated with epidermal growth factor receptor (EGFR) activation. Imatinib-induced changes were blocked with the EGFR antagonist cetuximab, which suggested direct involvement of EGFR in this process. Western blot analysis of cells incubated with imatinib demonstrated activation of EGFR and downstream signaling that was reduced by inhibition of mitogen-activated protein/extracellular signal-regulated kinase kinase 1 (MEK1) and EGFR, but not Her2/ErbB2. An in vitro kinase assay showed that imatinib did not directly affect EGFR kinase activity, suggesting involvement of EGFR-activating molecules. Inhibitors and neutralizing antibodies against heparin-binding epidermal growth factor-like growth factor (HB-EGF), and to a lesser extent transforming growth factor-alpha, reduced imatinib-mediated mitogen activated protein kinase (MAPK) activation. Imatinib stimulated the rapid release of soluble HB-EGF and the subsequent induction of membrane-bound HB-EGF, which correlated with biphasic MAPK activation. Together, these results suggested that imatinib affects EGFR activation and signaling pathways through rapid release and increased expression of endogenous EGFR-activating ligands. Although, imatinib primarily inhibits tyrosine kinases, it also stimulates the activity of EGFR tyrosine kinase in head and neck squamous tumors. This finding demonstrates the need for careful use of this drug in cancer patients.
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PMID:Induction of heparin-binding EGF-like growth factor and activation of EGF receptor in imatinib mesylate-treated squamous carcinoma cells. 1588 38

Vascular endothelial growth factor (VEGF) is a potent signalling molecule that acts through two tyrosine kinase receptors, VEGFR1 and VEGFR2. The upregulation of VEGF and its receptors is important in tumour-associated angiogenesis; however, recent studies suggest that several tumour cells express VEGF receptors and may be influenced by autocrine VEGF signalling. Rhabdomyosarcoma (RMS) is the most common paediatric soft-tissue sarcoma, and is dependent on autocrine signalling for its growth. The alveolar subtype of RMS is often characterized by the presence of a PAX3-FKHR translocation, and when introduced into non-RMS cells, the resultant fusion protein induces expression of VEGFR1. In our study, we examined the expression of VEGF and its receptors in RMS, and autocrine effects of VEGF on cell growth. VEGF and receptor mRNA and protein were found to be expressed in RMS cells. Exogenous VEGF addition resulted in extracellular signal-regulated kinase-1/2 phosphorylation and cell proliferation, and both were reduced by VEGFR1 blockade. Growth was also slowed by VEGFR1 inhibitor alone. Treatment of RMS cells with all-trans-retinoic acid decreased VEGF secretion and slowed cell growth, which was rescued by VEGF. These data suggest that autocrine VEGF signalling likely influences RMS growth and its inhibition may be an effective treatment for RMS.
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PMID:Vascular endothelial growth factor acts in an autocrine manner in rhabdomyosarcoma cell lines and can be inhibited with all-trans-retinoic acid. 1611 81


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