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)

Novartis has launched imatinib, an inhibitor of tyrosine kinases, including Bcr-Abl, for the treatment of chronic myeloid leukemia (CML). Imatinib selectively inhibits activation of target proteins involved in cellular proliferation. It also inhibits c-KIT tyrosine kinase activity and is equally effective against both wild-type and constitutively active enzyme. Close correlation between in vitro responses to IFNalpha and imatinib suggested that it may be an alternative to IFNalpha therapy for chronic-phase CML, and the compound has the advantage that it can be administered orally. Futhermore, Bcr-Abl-expressing cells treated with imatinib undergo apoptosis. Imatinib also has potential for the treatment of other cancers that express these kinases, including acute lymphocytic leukemia and certain solid tumors. In February 2002, the FDA approved imatinib for the treatment of inoperable and/or metastatic malignant gastrointestinal stromal tumors (GIST); in September 2001, launch for the indication was expected in 2002. In November 2000, imatinib was granted Orphan Drug status in Japan for the target indication of Philadelphia chromosome-positive leukemia. By May 2001, imatinib had entered phase II trials for small cell lung cancer, prostate cancer and glioma. Imatinib has been launched in more than 35 countries, including the US, Brazil, Switzerland, Australia and the UK. By December 2001, the drug had also been launched in Japan. The drug is marketed as Gleevec (imatinib mesilate) in the US, and Glivec (imatinib) outside the US. In August 2001, Deutsche Bank estimated sales of SFr 233 million in 2001, rising to SFr 850 million in 2005; while Bear Stearns & Co predicted sales of SFr 250 million in 2001, rising to SFr 800 million in 2005.
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PMID:Imatinib. Novartis. 1205 2

As a result of major recent advances in understanding the biology of gastrointestinal stromal tumors (GIST), specifically recognition of the central role of activating KIT mutations and associated KIT protein expression in these lesions, and the development of novel and effective therapy for GISTs using the receptor tyrosine kinase inhibitor STI-571, these tumors have become the focus of considerable attention among pathologists, clinicians, and patients. Stromal/mesenchymal tumors of the gastrointestinal tract have long been a source of confusion and controversy with regard to classification, line(s) of differentiation, and prognostication. Characterization of the KIT pathway and its phenotypic implications has helped to resolve some but not all of these issues. Given the now critical role of accurate and reproducible pathologic diagnosis in ensuring appropriate treatment for patients with GIST, the National Institutes of Health (NIH) convened a GIST workshop in April 2001 with the goal of developing a consensus approach to diagnosis and morphologic prognostication. Key elements of the consensus, as described herein, are the defining role of KIT immunopositivity in diagnosis and a proposed scheme for estimating metastatic risk in these lesions, based on tumor size and mitotic count, recognizing that it is probably unwise to use the definitive term benign for any GIST, at least at the present time.
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PMID:Diagnosis of gastrointestinal stromal tumors: a consensus approach. 1207 1

As a result of major recent advances in understanding the biology of gastrointestinal stromal tumors (GISTs), specifically recognition of the central role of activating KIT mutations and associated KIT protein expression in these lesions, and the development of novel and effective therapy for GISTs using the receptor tyrosine kinase inhibitor STI-571, these tumors have become the focus of considerable attention by pathologists, clinicians, and patients. Stromal/mesenchymal tumors of the gastrointestinal tract have long been a source of confusion and controversy with regard to classification, line(s) of differentiation, and prognostication. Characterization of the KIT pathway and its phenotypic implications has helped to resolve some but not all of these issues. Given the now critical role of accurate and reproducible pathologic diagnosis in ensuring appropriate treatment for patients with GIST, the National Institutes of Health convened a GIST workshop in April 2001 with the goal of developing a consensus approach to diagnosis and morphologic prognostication. Key elements of the consensus, as described herein, are the defining role of KIT immunopositivity in diagnosis and a proposed scheme for estimating metastatic risk in these lesions, based on tumor size and mitotic count, recognizing that it is probably unwise to use the definitive term "benign" for any GIST, at least at the present time.
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PMID:Diagnosis of gastrointestinal stromal tumors: A consensus approach. 1450 50

This paper reviews data on the prognosis of gastrointestinal stromal tumors (GISTs). These tumors are specific KIT-expressing and KIT-signaling-driven mesenchymal tumors, many of which have KIT-activating mutations. GISTs occur in the entire gastrointestinal (GI) tract and may also arise from the omentum, mesenteries, and retroperitoneum. They range from small benign tumors to sarcomas at all sites of occurrence. A KIT tyrosine kinase inhibitor, STI-571 (imatinib [Gleevec]; Novartis, Basel, Switzerland), has recently shown promise in the treatment of metastatic GISTs. Understanding the natural history of GIST before introduction of STI-571 will help assess the impact and position of this new treatment. The frequency of benign versus malignant GISTs varies between sites. Benign GISTs outnumber malignant GISTs in the stomach, whereas malignant GISTs are more common in the intestines. Tumors that have metastasized at presentation have a very poor prognosis. Traditionally, the 3 key prognostic factors have been mitotic rate, tumor size, and site. Tumors that are small (< or =2 cm) and show mitotic activity not exceeding 5 mitoses per 50 high-power fields (HPFs) have an excellent prognosis, probably independent of site, although this has not been shown specifically for all sites. In the stomach, most epithelioid GISTs are benign, provided that mitotic counts do not exceed 5/50 HPFs. However, a small proportion of tumors apparently lacking mitotic activity do metastasize. Tumors with a mitotic rate >5/50 HPFs usually have a malignant behavior. The Ki67 index may help identify tumors with malignant potential, but large site-specific series are not yet available. Genetic markers, including DNA-copy number changes, telomerase activity, and KIT mutation status, may be useful in more accurately identifying tumors with malignant potential.
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PMID:Evaluation of malignancy and prognosis of gastrointestinal stromal tumors: a review. 1209 72

Recent studies have done much to reveal the biological and genetic underpinnings of gastrointestinal stromal tumors (GISTs). Constitutive activation of the KIT receptor tyrosine kinase is a central pathogenetic event in most GISTs and generally results from oncogenic point mutations which can involve either extracellular or cytoplasmic domains of the receptor. Oncogenic mutations enable the KIT receptor to phosphorylate various substrate proteins, leading to activation of signal transduction cascades which regulate cell proliferation, apoptosis, chemotaxis, and adhesion. KIT mutations can be broadly assigned to 2 groups, those that involve the "regulatory" regions responsible for modulating KIT enzymatic activity and those that involve the enzymatic region itself. In vitro studies suggest that GISTs with regulatory-region KIT mutations are more likely to respond to STI-571 than are GISTs with enzymatic-region mutations. A minority of GISTs lack demonstrable KIT mutations, but KIT is nonetheless strongly activated. Such GISTs might contain KIT mutations which are not readily detected by conventional screening methods, or alternately, KIT might be activated by nonmutational mechanisms. Most GISTs have noncomplex cytogenetic profiles, often featuring deletions of chromosomes 14 and 22. Additional chromosomal aberrations are acquired as the GISTs progress to higher histologic grade. These cytogenetic aberrations are undoubtedly important in GIST pathogenesis, but currently they do not play a key role as diagnostic adjuncts.
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PMID:Biology and genetic aspects of gastrointestinal stromal tumors: KIT activation and cytogenetic alterations. 1209 73

Gastrointestinal stromal tumors (GISTs) with neurogenic differentiation, also referred to as "gastrointestinal autonomic nerve tumors (GANTs)," form an ultrastructurally distinctive subgroup of mesenchymal neoplasms of gastrointestinal tract. Cytogenetic and molecular data of these tumors are limited. In the current study, c-KIT gene sequenc-ing analysis, comparative genomic hybridization (CGH), and interphase fluorescence in situ hybrid- ization (FISH) analysis, utilizing chromosome 14- and 22-specific probes, were performed on five primary ultrastructurally confirmed GANTs. FISH and CGH analysis revealed loss of a whole or part of chromosome 14q in two tumors and of chromo- some 22q, with the common overlapping area of loss at q13, in all five tumors evaluated. c-KIT mu- tations were found in all cases; three tumors carried point mutation and/or deletions of exon 11, and in two tumors, insertion in exon 9 was found. These findings suggest that accumulated genetic changes contribute to the pathogenesis of GANTs and that 22q13 loss may be a characteristic feature of these tumors.
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PMID:Complex genetic alterations in gastrointestinal stromal tumors with autonomic nerve differentiation. 1211 5

The KIT-positive specific gastrointestinal stromal tumors (GISTs), leiomyomas, and schwannomas are the three most common types of primary mesenchymal tumors of the gastrointestinal (GI) tract. The intermediate filaments are abundant cytoskeletal proteins commonly used as cell differentiation markers in diagnostic immunohistochemistry. Their patterns have not been fully characterized in GI mesenchymal tumors, and could offer differential diagnostically useful parameters. Very recently, nestin, a class VI intermediate filament expressed in neuroectodermal stem cells and skeletal muscle progenitor cells, has been shown in GISTs and suggested as a marker for these tumors. In this study we immunohistochemically examined the expression of nestin and other intermediate filament proteins, including desmin, keratins (Ks), glial fibrillary acidic protein (GFAP), neurofilament, and vimentin in GISTs of different sites, esophageal leiomyomas and GI schwannomas. Nestin was nearly consistently present in GISTs of different locations whether spindle cell or epithelioid, and benign or malignant. It was also detected in 23 of 24 (96%) GI schwannomas, whereas leiomyomas were uniformly negative. Vimentin was present in both GISTs and schwannomas, whereas it was typically absent in leiomyomas (25% positive, usually focally). Desmin was present in all leiomyomas, whereas only 3% of GISTs (4 of 140) were positive, and all schwannomas were negative. K18 was detected in a minority of GISTs, leiomyomas, and schwannomas. Malignant GISTs were more commonly keratin positive than the benign ones; there was 18% K18 positivity in malignant gastric and small intestinal GISTs, but 9% K18 positivity in benign gastric and small intestinal GISTs. Moreover, K8, albeit to a lesser degree, was detected in a minority of GISTs, but K7, K14, K19 and K20 were not detected. GFAP was present in the majority of schwannomas, whereas all GISTs were negative; some leiomyomas had weak cytoplasmic positivity. These results document distinctive patterns of intermediate filament proteins in GI mesenchymal tumors. Nestin is confirmed to be consistently expressed in GISTs but it is also present in most GI schwannomas; GFAP is helpful when separating GISTs and schwannomas, since only the latter are positive. The potential presence of K8 and K18 in GISTs should not lead to the misdiagnosis of carcinoma on biopsy.
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PMID:Patterns of nestin and other intermediate filament expression distinguish between gastrointestinal stromal tumors, leiomyomas and schwannomas. 1219 11

Primary mediastinal seminomas (MS) are rare tumors that are histologically similar to their testicular counterparts. Reports document KIT mutations in gastrointestinal stromal tumors, mastocytosis, and germ cell tumors. Although rare exon 17 mutations have been reported in gonadal seminomas, their mediastinal counterparts have not been studied. To determine whether primary MS harbor KIT mutations, eight formalin-fixed, paraffin-embedded primary MS were microdissected; KIT exons 11 and 17 were sequenced. Four (50%) of the eight cases demonstrated KIT exon 17 mutations. Two of the cases showed single monoallelic base pair alterations; one of these mutations were silent. The other two cases each demonstrated two monoallelic point mutations. In each case, one of these mutations results in protein sequence alteration, and the other is silent. Sequencing of cloned PCR products showed both the silent and amino acid-altering mutations to be found on the same allele (cis). The codon 816 mutation previously identified in mastocytosis and gonadal germ cell tumors was not observed. Non-neoplastic tissues from these patients did not demonstrate KIT mutations; exon 11 mutations were not seen in either tumors or normal tissues. Only the three cases in which amino acid-altering mutations were observed showed a predominantly cytoplasmic CD177 KIT immunohistochemical staining, whereas the one non-amino acid mutating and all wild-type cases were immunonegative. Our findings demonstrate a unique KIT sequence and expression pattern among MS. KIT sequencing may assist in differentiating primary from metastatic MS.
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PMID:Primary mediastinal seminomas: evidence of single and multiple KIT mutations. 1237 71

Gastrointestinal stromal tumors (GIST) represent the most common type of mesenchymal malignancy in the gastrointestinal tract. With the discovery of uncontrolled KIT tyrosine kinase signaling as a critical component in the pathogenesis of this disease, the diagnostic and treatment options for patients with GIST have evolved rapidly. Pathology review by an experienced pathologist is critical to the classification of this disease. Expert and definitive surgery remains the mainstay of treatment in patients with localized, resectable disease. Imatinib mesylate has been shown to be the first successful systemic therapy for patients with metastatic or unresectable disease and has revolutionized the treatment of this often rapidly progressive and fatal disease. Ongoing studies are evaluating the role of imatinib in the preoperative and postsurgical adjuvant settings. Although resistance to imatinib will appear over time, there is reason for optimism that the mechanisms of resistance will be identified and eventually overcome. The application of molecular understanding of GIST to the development of a selective, scientifically rational therapy is a classic example of multidisciplinary translational oncology research.
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PMID:Management of gastrointestinal stromal tumors in the era of tyrosine kinase inhibitors. 1239 38

Tumors of the small bowel are uncommon. Most of them are malignant neoplasmas with bad outcome. To ameliorate the doubtful prognosis tumors should be clarified carefully by means of histological, immunohistochemical and molecular methods. Patients suffering from familial adenomatous polyposis are at high risk to develop adenomas and adenocarcinomas of the duodenum. Therefore, the upper gastrointestinal tract should be monitored endoscopically in regular intervals. Surgically unresectable or metastatic malignant gastrointestinal stromal tumors should be included in an EORTC trial assessing the clinical activity of STI-571. This agent inhibits KIT-tyrosine kinase activity thus leading to a reduction of the tumor mass. Moreover, the WHO classification of lymphomas enables a more precise prognosis and individually tailored therapeutic strategies in primary lymphomas of the small bowel.
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PMID:[Tumors of the small intestine]. 1242 74


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