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)

Gastrointestinal stromal tumours (GISTs) are considered to originate from interstitial cells of Cajal (ICCs). ICCs are classified into several subtypes according to their location or roles. Several reports indicate that GISTs of the small intestine appear to have different clinical and pathological characteristics from gastric GISTs. We previously found using a cDNA expression chip that connexin 43, a component of gap junctions, is expressed specifically in small intestinal GISTs but not in gastric GISTs. To confirm the specificity of connexin 43 expression, we analysed 10 small intestinal GISTs and 15 gastric GISTs by northern blotting, western blotting and immunohistochemistry in this study. Northern blotting was performed in five small intestinal GISTs and five gastric GISTs, and revealed connexin 43 mRNA expression in all of the five small intestinal GISTs, but in none of the gastric GISTs. By western blotting, bands corresponding to connexin 43 were easily detected in all of the five small intestinal GISTs studied but were absent in all five gastric GISTs analysed. Immunohistochemistry showed that all of the 10 small intestinal GISTs were positive for connexin 43 but only one of 15 gastric GISTs, which exhibited a mutation in exon 9 of the KIT gene, was connexin 43-positive. We also examined the localization of connexin 43 in the normal stomach and small intestine. Immunoreactivity for connexin 43 was present in both normal gastric and small intestinal circular muscle layers, but it was unclear which cell type was positive. These results suggest that GISTs are divided into at least two groups, namely the gastric subtype and the small intestinal subtype, through phenotype but not location. Furthermore, these data indicate that the gastric and the small intestinal subtypes of GIST may originate from different subtypes of ICC.
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PMID:Differential expression of connexin 43 in gastrointestinal stromal tumours of gastric and small intestinal origin. 1593 3

Until recently, there were few effective therapeutic options for patients with gastrointestinal stromal tumors (GISTs). Most patients undergoing even potentially curative resection for early-stage disease recurred if followed for a sufficiently long period, and treatment of advanced tumors with systemic chemotherapy was ineffective. Imatinib mesylate, a molecularly targeted agent that inhibits the KIT receptor tyrosine kinase, has now been demonstrated to be highly effective at inducing objective responses in GIST patients, and it improves overall survival. In locoregional disease, ongoing studies are assessing the use of imatinib pre-or postsurgery. In addition, other agents possessing activity against a variety of molecular targets are being tested in advanced disease. Questions remain about the optimal dose of imatinib, whether to continue drug in the setting of progressive disease, and how best to prevent or overcome resistance.
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PMID:State-of-the art therapy for gastrointestinal stromal tumors. 1594 12

We report a gastrointestinal stromal tumor (GIST) patient with male gynecomastia and testicular hydrocele after treatment with imatinib mesylate. A 42 yr-old male patient presented for management of hepatic masses. Two years earlier, he had undergone a small bowel resection to remove an intraabdominal mass later shown to be a GIST, followed by adjuvant radiation therapy. At presentation, CT scan revealed multiple hepatic masses, which were compatible with metastatic GIST, and he was prescribed imatinib 400 mg/day. During treatment, he experienced painful enlargement of the left breast and scrotal swelling. Three months after cessation of imatinib treatment, the tumors recurred, and, upon recommencing imatinib, he experienced painful enlargement of the right breast and scrotal swelling. He was diagnosed with male gynecomastia caused by decreased testosterone and noncommunicative testicular hydrocele. He was given androgen support and a hydrocelectomy, which improved his gynecomastia. The mechanism by which imatinib induces gynecomastia and hydrocele is thought to be associated with an inhibition of c-KIT and platelet-derive growth factor. This is the first report, to our knowledge, describing concurrent male gynecomastia and testicular hydrocele after imatinib treatment of a patient with GIST.
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PMID:Concurrent male gynecomastia and testicular hydrocele after imatinib mesylate treatment of a gastrointestinal stromal tumor. 1595 81

Gastrointestinal stromal tumors (GISTs): clinical and pathological features. The gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. With immunohistochemical, electron microscope and molecular examinations they can be clearly distinguished in both their genotype and phenotype from other mesenchymal tumors. GIST tumors express the CD 117 receptor in more than 90% independent of histopathological features and clinical behaviour. This is why it is considered as the most important characteristic. The incidence is 10-20 new cases per 1 million annually. The number of incidents is expected to increase by the establishment of CD117 and other new markers (protein kinase C theta, DOG1). Nowadays the establishment of the expected biological behavior and malignancy can be difficult. The best prognostic factors are the tumor size and the mitotic index. Dominantly, due to the mutation of the c-kit proto-oncogene and PGDFRA gene that the high level tyrosine kinase activity generates resulting uncontrolled proliferation and cell growth. The imatinib mesylate is a selective inhibitor of the KIT tyrosine kinase receptor and it also blocks the activity of the PDGFRA kinase. The therapeutic consequence of this is that the majority of advanced GIST tumors which do not react to conventional radio- and chemotherapy respond well to tyrosine kinase inhibitor treatment. As a result, survival and patient's quality of life can significantly improve.
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PMID:[Gastrointestinal stromal tumors (GISTs): clinical and pathological features]. 1605 79

Mutations of proto-oncogene c-kit in gastrointestinal stromal tumors (GISTs) are considered to cause a constitutive activation of KIT responsible for their oncogenesis. Imatinib has therapeutic potential for GISTs because of its inhibitory effect on KIT kinase activity. However, no study has been published concerning the effects of imatinib on GIST cells with various types of KIT mutation. To investigate the effects of imatinib on various c-kit mutations found in GISTs, cell proliferation and apoptosis assays were performed in two GIST cell lines with different KIT mutations. One of the cell lines, GIST-T1, revealed a heterozygous deletion of exon 11 in the c-kit, while the other cell line, GIST882, possessed a homozygous missense mutation of exon 13 in the c-kit gene. Imatinib inhibited proliferation and induced apoptosis in both cell lines. Imatinib potently suppressed proliferation of the GIST882 cell line at the concentration of 1.0 microM, whereas it inhibited the GIST-T1 at 0.1 microM. In two types of activating mutant KIT, imatinib could inhibit the constitutive activation of both types of KIT mutant, although the antiproliferative effect on GIST882 was weaker than on GIST-T1. Western blot analysis revealed that apoptosis related proteins were activated or suppressed by imatinib in both cell lines in the respective manner. Our results suggest that the apoptotic signal trans-duction caused by imatinib in GISTs is susceptible to various types of KIT mutation.
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PMID:Effects of imatinib vary with the types of KIT-mutation in gastrointestinal stromal tumor cell lines. 1607 68

There is now considerable interest in gastrointestinal stromal tumor (GIST) because it can be treated effectively with a targeted molecular agent. The majority of GISTs contain an activating mutation in the KIT protooncogene or, occasionally, in the platelet-derived growth factor-alpha (PDGFRA) gene. Five years ago, imatinib mesylate, a specific molecular inhibitor of the protein products of these 2 genes, was applied to metastatic GIST. Approximately 80% of patients with metastatic GIST benefit from imatinib, although acquired resistance to the agent may develop. For patients with primary GIST, surgery remains the treatment of choice, and whether outcome is improved by adjuvant imatinib is currently under broad investigation. A combination of imatinib therapy and surgery also may be effective in a subset of patients with metastatic or unresectable primary GIST. In this review, the authors summarize the new multimodality approach to GIST. The integration of surgery and molecular therapy in GIST will serve as a prototype for the management of other solid tumors for which targeted agents become available.
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PMID:Gastrointestinal stromal tumor: 5 years later. 1613

We report on the first case of benign perineurially differentiated peripheral nerve sheath tumor (perineurioma) presenting as a bleeding gastric mass in a 30-year-old, previously healthy woman with no signs or stigmata of von Recklinghausen's disease or other primary tumor at time of presentation. Gastric resection specimen revealed an ulcerated moderately cellular mesenchymal tumor consisting of elongated wavy spindle cells arranged in a fascicular and sheet-like pattern with focal whorling and occasional alternation of dark staining cellular and light staining hypocellular areas. Tumor cells were strongly immunoreactive for epithelial membrane antigen, CD56 (N-CAM), and vimentin, but were negative for S-100-protein and other lineage-specific epithelial, mesenchymal, hematolymphoid, and reticulo-histiocytic markers. CD117 revealed numerous positive staining mast cells, but the lesional cells were not reacting. We presume that the combined histological and immunohistochemical profiles of this unusual gastric neoplasm are consistent with a diagnosis of perineurioma with a probably benign biological behavior. To our knowledge, this is the first report of gastric perineurioma, an extremely rare mesenchymal lesion that should be considered among the differential diagnoses of gastrointestinal stromal tumor, especially the so-called KIT-negative GIST. Gastrointestinal perineuriomas might be under-recognized, as our case was initially diagnosed as a benign GIST.
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PMID:Perineurioma of the stomach. A rare spindle cell neoplasm that should be distinguished from gastrointestinal stromal tumor. 1613 53

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.
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PMID:Pathophysiology, diagnosis, and treatment of gastrointestinal stromal tumors. 1614 81

Gastrointestinal stromal tumors (GISTs), specific KIT- or PDFGRA-signaling driven mesenchymal tumors, are rare in children and young adults, and their clinicopathologic and molecular genetic profile is incompletely understood. In this study, we analyzed 44 gastric GISTs occurring by the age of 21 years. There were 32 females and 12 males, youngest of whom were a 5-year-old boy and an 8-year-old girl. All but 1 of 25 patients under the age of 16 were girls. The patients most commonly received medical attention because of chronic, insidious gastrointestinal bleeding with anemia, less commonly with acute GI bleeding. Only 1 patient had Carney triad with pulmonary chondroma. None of the patients had family members with GIST. The tumors measured from 1.5 to 24 cm (median, 5.6 cm). A total of 21 tumors with specified location were in the antrum and 8 were in the gastric body. Histologically, 26 tumors were composed of epithelioid cells, 12 of spindle cells, and 6 of combination thereof. Mitotic activity varied form 0 to 65/50 HPF (median, 5/50). All but one of the 24 tumors tested were KIT-positive, and 20 were CD34-positive. Eleven patients developed liver or abdominal metastases, and 6 of them died of tumor surviving 5.5 to 35.5 years (median, 16 years) after the first surgery; three of these tumors had a low mitotic activity and size <10 cm. Twenty-one patients were alive with no evidence for disease 7 to 41 years (median, 17 years) after the first surgery. None of the 13 tumors examined (7 of them 8- to 16-year-old females) had KIT exon 9, 11, 13, or 17 or PDGFRA exon 12 or 18 mutation as typically seen in adult GISTs. Gastric GISTs in children have mainly epithelioid morphology, often occur in antrum, and have a somewhat unpredictable but slow course of disease. Their pathogenesis may differ from that of adult GISTs because no KIT or PDGFRA mutations were found; connection with Carney triad seems infrequent despite demographic and histologic similarities.
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PMID:Gastrointestinal stromal tumors of the stomach in children and young adults: a clinicopathologic, immunohistochemical, and molecular genetic study of 44 cases with long-term follow-up and review of the literature. 1616 Apr 81

Gastrointestinal stromal tumors (GISTs) historically have differed from other soft-tissue sarcomas in demonstrating a particularly grim prognosis. GISTs have an extraordinarily high rate of recurrence after surgical resection and are highly resistant to radiation and standard chemotherapy. The discovery that constitutive activation of the c-kit gene drives malignant behavior in GISTs exposed a weakness that was soon exploited through the application of the novel targeted therapy imatinib, a small-molecule tyrosine kinase inhibitor of Bcr-Abl, KIT, and the platelet-derived growth factor receptor-alpha and -beta. Imatinib had shown unparalleled results in patients with advanced chronic myelogenous leukemia (remission rates approaching 98%), and the first GIST patients treated with imatinib demonstrated dramatic response rates unseen with other therapeutic modalities. Thousands of patients worldwide with advanced GIST have been treated with imatinib, with the demonstration of significant response rates, prolongation of survival, and improvement in quality of life. Studies of imatinib in both the neoadjuvant and adjuvant settings are now being conducted to evaluate whether low rates of cure with surgical resection alone can be improved. Additionally, multiple new targeted agents are being tested in patients with imatinib-resistant GIST. The gains that have been made in the treatment of GIST through the use of imatinib have helped to open the door to a new era of development of targeted therapeutic agents in oncology. Whether this new era of targeted therapy will provide the same advances in more common malignancies will be determined only through the ongoing application and development of clinical trials.
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PMID:Gastrointestinal stromal tumors and the evolution of targeted therapy. 1616 51


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