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

---

Query: EC:2.7.10.2 (focal adhesion kinase)
44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Conventional chemotherapeutic drugs are ineffective in treatment of gastrointestinal stromal tumors (GISTs). Imatinib (STI571, Gleevec, Glivec; Novartis Pharmaceuticals, East Hanover, NJ), a selective inhibitor of KIT, ABL, BCR-ABL, PDGFRA, and PDGFRB, represents a new paradigm of targeted cancer therapy and has revolutionized the treatment of patients with chronic myelogenous leukemia and GISTs. Unfortunately, imatinib resistance has emerged. The reported mechanism of imatinib resistance in GISTs involves missense mutation in the kinase domain of KIT, including Thr670Ile, Tyr823Asp, and Val654Ala. The established mechanisms and potential mechanisms of imatinib resistance in GISTs, the imaging studies indicative of early development of imatinib resistance, and the management of imatinib-resistant GISTs are discussed.
...
PMID:Imatinib resistance in gastrointestinal stromal tumors. 1594 89

Oncogenic mutations of the receptor tyrosine kinase KIT are encountered in myeloid leukemia and various solid tumors, including gastrointestinal stromal tumors. We previously identified the human oncogenic germ line mutant KIT(K642E), a substitution in the tyrosine kinase 1 domain (TK1D) in a familial form of gastrointestinal stromal tumors. The effects of oncogenic KIT mutants on cell signaling and regulation are complex. Cellular models are valuable basic tools to tailor novel strategies on specific cellular and molecular bases for tumors expressing KIT oncogenic mutants. Murine KIT(WT) and the murine homologues of human KIT oncogenic mutants, further referred to as KIT(K641E) and KIT(del559), a point deletion in the juxtamembrane domain (JMD), were stably expressed in IL-3-dependent Ba/F3 cells. Major differences in the constitutively activation of Akt/PKB, MAP kinases and STATs pathways were observed between KIT(K641E) and KIT(del559), whereas KIT ligand elicited responses in both mutants. Noteworthy, the protein level of the phosphoinositide phosphatase SHIP1, but not SHIP2 and PTEN, was reduced in KIT(K641E) only while inhibition of KIT phosphorylation reversibly raised SHIP1 level in both JMD and TK1D oncogenic mutants, unraveling the control of SHIP protein level by KIT phosphorylation.
...
PMID:Differences in signaling pathways and expression level of the phosphoinositide phosphatase SHIP1 between two oncogenic mutants of the receptor tyrosine kinase KIT. 1599 Feb 78

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. Activating mutations of KIT or the platelet-derived growth factor receptor alpha gene (PDGFRA) have been identified in the vast majority of GISTs. The respective oncoproteins exhibit constitutive tyrosine kinase activity and promote cell growth. KIT and PDGFRA mutations are rarely found in GISTs in patients with neurofibromatosis type 1 (NF1) suggesting that the pathogenesis of GIST in NF1 patients is different from that in non-NF1 patients. Endoscopic diagnosis of GIST is usually difficult. Endoscopic ultrasonography (EUS)-guided fine-needle aspiration biopsy (EUS-FNAB) is a useful method for the diagnosis of GIST and for the detection of KIT or PDGFRA mutations. Imatinib mesylate, a tyrosine kinase inhibitor known to inhibit the activities of BCR-ABL, KIT, and PDGFR, is currently being used for the treatment of both chronic myeloid leukemia and metastatic GIST. The clinical response to imatinib therapy correlates with the types of mutations of KIT and PDGFRA, and the determination of KIT and PDGFRA mutations is useful for predicting the effect of imatinib. Resistance to imatinib after an initial response has been reported; secondary point mutations in KIT or PDGFRA that confer imatinib resistance are the most common mechanisms responsible for acquired resistance to imatinib. The continued development of target-specific therapies should increase the probability of cure in most patients with GISTs.
...
PMID:Pathophysiology, diagnosis, and treatment of gastrointestinal stromal tumors. 1614 81

Acquired resistance to imatinib mesylate is an increasing and continued challenge in the treatment of BCR-ABL tyrosine kinase positive leukemias as well as gastrointestinal stromal tumors. Stable isotope-based dynamic metabolic profiling (SIDMAP) studies conducted in parallel with the development and clinical testing of imatinib revealed that this targeted drug is most effective in controlling glucose transport, direct glucose oxidation for RNA ribose synthesis in the pentose cycle, as well as de novo long-chain fatty acid synthesis. Thus imatinib deprives transformed cells of the key substrate of macromolecule synthesis, malignant cell proliferation, and growth. Tracer-based magnetic resonance spectroscopy studies revealed a restitution of mitochondrial glucose metabolism and an increased energy state by reversing the Warburg effect, consistent with a subsequent decrease in anaerobic glycolysis. Recent in vitro SIDMAP studies that involved myeloid cells isolated from patients who developed resistance against imatinib indicated that non-oxidative ribose synthesis from glucose and decreased mitochondrial glucose oxidation are reliable metabolic signatures of drug resistance and disease progression. There is also evidence that imatinib-resistant cells utilize alternate substrates for macromolecule synthesis to overcome limited glucose transport controlled by imatinib. The main clinical implications involve early detection of imatinib resistance and the identification of new metabolic enzyme targets with the potential of overcoming drug resistance downstream of the various genetic and BCR-ABL-expression derived mechanisms. Metabolic profiling is an essential tool used to predict, clinically detect, and treat targeted drug resistance. This need arises from the fact that targeted drugs are narrowly conceived against genes and proteins but the metabolic network is inherently complex and flexible to activate alternative macromolecule synthesis pathways that targeted drugs fail to control.
...
PMID:Detection of resistance to imatinib by metabolic profiling: clinical and drug development implications. 1619 99

Imatinib mesylate (STI571) is an oral 2-phenylaminopyrimidine derivative that acts as a selective inhibitor against several receptor tyrosine kinases and has been viewed as one of the therapeutic success stories of the 21st century. Imatinib was first shown to inhibit the causative molecular translocation in chronic myelogenous leukemia, BCR-ABL. Because imatinib could also inhibit the activity of KIT, a 145-kD transmembrane glycoprotein, and because gastrointestinal stromal tumors (GISTs), the most common mesenchymal tumors of the digestive tract, are characterized by expression of a gain-of-function mutation in KIT, imatinib was used in therapeutic trials of GISTs beginning in 1999. The initial success has now resulted in more widespread use of imatinib for the treatment of patients with GIST. Molecular genetic studies have shown that most GISTs possess a KIT mutation in exon 9, 11, 13, or 17. Clinically, GIST patients with KIT exon 11 mutations (ie, the juxtamembrane region) are the most prevalent and sensitive to imatinib. In addition to the inhibitory effect on KIT, imatinib also inhibits the activity of mutant platelet-derived growth factor receptor-alpha (PDGFRalpha) found in a subset of GIST. What is becoming evident is that there are patients with GIST who lack mutations in KIT or PDGFRalpha, or possess "imatinib-resistant" mutations (such as exon 17 mutations in KIT and exon 18 mutations in PDGFRalpha). These patients typically do not respond well to imatinib therapy. Therefore, identifying additional genetic factors that contribute to the pathogenesis of GIST, independent of KIT and PDGFRalpha, will be important in developing additional anti-GIST therapies. As one might suspect from previous experiences with antitumor therapies, primary and secondary resistance to imatinib is also becoming a major clinical problem in the treatment of this disease. Therefore, new drugs that can serve as alternative therapies in imatinib-resistant patients with GIST or that can be used in combination with imatinib will be needed. As with most recent efforts to derive novel molecular target therapies to treat cancer, improved therapy of GIST will continue to benefit from advances in the molecular characterization of this disease.
...
PMID:Molecular research directions in the management of gastrointestinal stromal tumors. 1624 52

Activating mutations of the activation loop of KIT are associated with certain human neoplasms, including the majority of patients with systemic mast cell disorders, as well as cases of seminoma, acute myelogenous leukemia (AML), and gastrointestinal stromal tumors (GISTs). The small-molecule tyrosine kinase inhibitor imatinib mesylate is a potent inhibitor of wild-type (WT) KIT and certain mutant KIT isoforms and has become the standard of care for treating patients with metastatic GIST. However, KIT activation loop mutations involving codon D816 that are typically found in AML, systemic mastocytosis, and seminoma are insensitive to imatinib mesylate (IC50 > 5-10 micromol/L), and acquired KIT activation loop mutations can be associated with imatinib mesylate resistance in GIST. Dasatinib (formerly BMS-354825) is a small-molecule, ATP-competitive inhibitor of SRC and ABL tyrosine kinases with potency in the low nanomolar range. Some small-molecule SRC/ABL inhibitors also have potency against WT KIT kinase. Therefore, we hypothesized that dasatinib might inhibit the kinase activity of both WT and mutant KIT isoforms. We report herein that dasatinib potently inhibits WT KIT and juxtamembrane domain mutant KIT autophosphorylation and KIT-dependent activation of downstream pathways important for cell viability and cell survival, such as Ras/mitogen-activated protein kinase, phosphoinositide 3-kinase/Akt, and Janus-activated kinase/signal transducers and activators of transcription. Furthermore, dasatinib is a potent inhibitor of imatinib-resistant KIT activation loop mutants and induces apoptosis in mast cell and leukemic cell lines expressing these mutations (potency against KIT D816Y >> D816F > D816V). Our studies suggest that dasatinib may have clinical efficacy against human neoplasms that are associated with gain-of-function KIT mutations.
...
PMID:Dasatinib (BMS-354825), a dual SRC/ABL kinase inhibitor, inhibits the kinase activity of wild-type, juxtamembrane, and activation loop mutant KIT isoforms associated with human malignancies. 1639 63

STI571 is a specific inhibitor of tyrosine kinases, such as BCR-ABL, platelet-derived growth factor receptor, and c-KIT, and has recently been approved for the treatment of chronic myeloid leukemia and gastrointestinal stromal tumors (GISTs). This study demonstrated that STI571 induces cell death in the gastrointestinal stromal tumor cell line, GIST-T1. In these cells, STI571 induced pro-caspase-12 or pro-caspase-7 cleavage and it affected caspase-3 activity and induced the endoplasmic reticulum (ER)-resident chaperone, glucose-regulated protein 78. The STI571-induced cell death was blocked by the protein synthesis inhibitor, cycloheximide. Together, these results suggest that STI571 induces cell death in GIST-T1 cells, at least in part, via the ER stress response.
...
PMID:STI571 (Glivec) induces cell death in the gastrointestinal stromal tumor cell line, GIST-T1, via endoplasmic reticulum stress response. 1659 77

Most gastrointestinal stromal tumors (GISTs) possess a gain-of-function mutation in c-KIT. Imatinib mesylate, a small-molecule inhibitor against several receptor tyrosine kinases, including KIT, platelet-derived growth factor receptor-alpha, and BCR-ABL, has therapeutic benefit for GISTs both via KIT and via unknown mechanisms. Clinical evidence suggests that a potential therapeutic benefit of imatinib might result from decreased glucose uptake as measured by positron emission tomography using 18-fluoro-2-deoxy-d-glucose. We sought to determine the mechanism of and correlation to altered metabolism and cell survival in response to imatinib. Glucose uptake, cell viability, and apoptosis in GIST cells were measured following imatinib treatment. Lentivirus constructs were used to stably express constitutively active AKT1 or AKT2 in GIST cells to study the role of AKT signaling in metabolism and cell survival. Immunoblots and immunofluorescent staining were used to determine the levels of plasma membrane-bound glucose transporter Glut4. We show that oncogenic activation of KIT maximizes glucose uptake in an AKT-dependent manner. Imatinib treatment markedly reduces glucose uptake via decreased levels of plasma membrane-bound Glut4 and induces apoptosis or growth arrest by inhibiting KIT activity. Importantly, expression of constitutively active AKT1 or AKT2 does not rescue cells from the imatinib-mediated apoptosis although glucose uptake was not blocked, suggesting that the potential therapeutic effect of imatinib is independent of AKT activity and glucose deprivation. Overall, these findings contribute to a clearer understanding of the molecular mechanisms involved in the therapeutic benefit of imatinib in GIST and suggest that a drug-mediated decrease in tumor metabolism observed clinically may not entirely reflect therapeutic efficacy of treatment.
...
PMID:Therapeutic effect of imatinib in gastrointestinal stromal tumors: AKT signaling dependent and independent mechanisms. 1670 77

Most gastrointestinal stromal tumors (GISTs) express oncogenic and constitutively active forms of the KIT or platelet-derived growth factor receptor alpha (PDGFRA) receptor tyrosine kinase proteins, and these kinase oncoproteins serve as targets for effective therapies. Given that mutant KIT oncoproteins serve crucial transforming roles in GISTs, we evaluated interactions with the KIT oncoproteins and determined signaling pathways that are dependent on KIT oncogenic activation in GISTs. Tyrosine-phosphorylated KIT oncoproteins interacted with PDGFRA, PDGFRB, phosphatidylinositol 3-kinase (PI3-K) and PKCtheta in GIST cells, and these interactions were abolished by KIT inhibition with imatinib or PKC412 or KIT RNAi. Notably, tyrosine-phosphorylated PDGFRA was prominent in frozen GIST tumors expressing KIT oncoproteins, suggesting that KIT-mediated PDGFRA phosphorylation is an efficient and biologically consequential mechanism in GISTs. Activated signaling intermediates were identified by immunoaffinity purification of tyrosine-phosphorylated proteins in GIST cells before and after treatment with KIT inhibitors, and these analyses show that GRB2, SHC, CBL and MAPK activation are largely KIT dependent in GISTs, whereas PI3-K, STAT1 and STAT3 activation are partially KIT dependent. In addition, we found that phosphorylation of several tyrosine kinase proteins - including JAK1 and EPHA4 - did not depend on KIT activation. Likewise, paxillin activation was independent of the KIT oncogenic signal. These studies identify signaling pathways that can provide both KIT-dependent and KIT-independent therapeutic synergies in GIST, and thereby highlight clinical strategies that might consolidate GIST therapeutic response to KIT/PDGFRA inhibition.
...
PMID:KIT oncoprotein interactions in gastrointestinal stromal tumors: therapeutic relevance. 1745 78

Gastrointestinal stromal tumors GIST are rare mesenchymal tumors of the gastrointestinal tract characterized by expression of a receptor that activates tyrosine kinase called C- kit. Since malignant GIST has an extremely poor prognosis even after surgical resection. The developement of a tyrosine kinase inhibitor, STI571/imatinib mesylate/Gleevec, Glivec which inhibits the BCR-ABL, PDGF-R alpha, and C-Kit receptors, has changed the management of unresectable malignant GIST and has improved the survival of patients with metastaic disease. We report a 32 year old male patient with subcardiale gastric GIST and massive gastrointestinale bleeding. The patient underwent total gastrectomy, D2 lymphadenestomy, distal pancreatectomy and splenectomy on 02.02. 2004. Histopathology examination of the primary tumor revealed a strong C-Kit expression and CD 34 +++, Ki67 20 and so called "Pure GIST" was approved Liver metastasis was detected on ultrasound and CT 12 months later and segmentectomy S7 was performed on 23.03.2005. Postoperative course was uneventfull. HP examination--malignant 35 x 30 mm sarcoma like tumor of mesenchymal origin. The patient received adjuvant imatinib-mesylate Gleevec Novartis Pharma Basel 400 mg a day. The initial complete response to treatment continued to 24 monts postoperatively Imatinib is a recent and very promising tretemenextirpation remains the only curative treatment of malignant GIST as evideneced by our patient.
...
PMID:[Gastrointestinal gastric tumor (GIST) as a cause of massive hemorrhage from the upper digestive tract]. 1763 80


<< Previous 1 2 3 4 5 6 Next >>

---