Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P10721 (c-kit)
 6,575 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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

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

KIT is expressed in most gastrointestinal stromal tumors, and they usually show c-kit aberrations (most frequently deletions or deletions coexisting with a single or multiple point mutations). Recently, several studies regarding KIT expression in gynecologic tumors have been reported; however, their outcomes were not consistent. In this study, we immunohistochemically examined KIT expression in sarcomas of the female genital tract and studied the existence of c-kit aberrations to elucidate the characteristics of KIT-positive tumors in the gynecologic region. Formalin-fixed, paraffin-embedded tissues from 25 surgically resected and 1 biopsy specimen from 26 patients were used. Histological diagnoses included 14 uterine leiomyosarcomas, 6 carcinosarcomas, 5 endometrial stromal sarcomas, and 1 vaginal epithelioid sarcoma. Immunohistochemical studies were performed using anti-KIT polyclonal antibody. Only four of the above tumors (15%) were positive for KIT, all of which were carcinosarcomas. Specific KIT immunoreactivity was observed in the only carcinomatous components in one case, in the only sarcomatous component in two cases, and in the both components in one case. However, none of the cases showed c-kit aberrations in exons 9, 11, 13, and 17. Judicious decision is mandatory before applying Imatinib therapy to KIT-positive gynecologic tumors.
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PMID:Immunohistochemical evaluation of KIT expression in sarcomas of the gynecologic region. 1630 88

Protein phosphorylation on serine/threonine or tyrosine residues represents a significant regulatory mechanism in signal transduction during spermatogenesis, oogenesis, and fertilization. There are several families of tyrosine protein kinases operating during spermatogenesis: the Src family of tyrosine protein kinases; the Fujinami poultry sarcoma/feline sarcoma (Fps/Fes) and Fes-related protein (Fer) subfamily of non-receptor proteins; and c-kit, the transmembrane tyrosine kinase receptor that belongs to the family of the PDGF receptor. A remarkable characteristic is the coexistence of full-length and truncated tyrosine kinases in testis. Most of the truncated forms are present during spermiogenesis. Examples include the truncated forms of Src tyrosine kinase hematopoietic cell kinase (Hck), FerT, and tr-kit. A feature of FerT and tr-kit is the kinase domain that ensures the functional properties of the truncated protein. FerT, a regulator of actin assembly/disassembly mediated by cortactin phosphorylation, is present in the acroplaxome, a cytoskeletal plate containing an F-actin network and linking the acrosome to the spermatid nuclear envelope. This finding suggests that Fer kinase represents one of the tyrosine protein kinases that may contribute to spermatid head shaping. The c-kit ligand, stem cell factor (SCF), which induces c-kit dimerization and autophosphorylation, exists as both membrane-associated and soluble. Although tyrosine protein kinases are prominent in spermatogenesis, a remarkable observation is the paucity of phenotypic alterations in spermatogenic cells in male mice targeted with Fer kinase-inactivating mutation. It is possible that the redundant functions of the tyrosine protein kinase pool present during spermatogenesis may explain the limited phenotypes of single mutant mice. The production of compound and viable mutant mice, lacking the expression of two or more tyrosine kinases, may shed light on this intriguing issue.
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PMID:Tyrosine protein kinases and spermatogenesis: truncation matters. 1643 22

Human gastrointestinal stromal tumors (GIST) have recently emerged as a distinct mesenchymal tumor type that has a unique phenotype characterized by a gain of function mutations in c-kit. In contrast, leiomyosarcomas (LMS) of the gastrointestinal tract or retroperitoneum, which were previously classified together with GISTs as gastrointestinal sarcomas, have much less frequent mutations of c-kit. We performed microarray analyses to gain a comprehensive understanding of the difference between the two types of soft-tissue sarcomas at the level of gene expression. Microarray experiments were performed on 30 GISTs and 30 LMSs that were collected at the time of surgical resection. These tumors were categorized based on the histopathologic diagnosis recorded in our institutional database. Prior to our search for genes that are differentially expressed between these two types of cancers, we first carried out an unsupervised analysis using multidimensional scaling (MDS) to determine whether the two groups have marked overall differences in gene expression. Initially, the MDS did not reveal a good separation between the two groups. We then re-reviewed the histopathology of these tumors and realized that some of the cases included in our study were acquired 10 years ago when the diagnosis of gastrointestinal sarcoma was made according to histopathologic criteria alone without immunohistochemistry for c-kit. An experienced pathologist reviewed all of the specimens and this revealed that a number of the GIST cases were classified as LMS in the clinical database. Correction of the histopathologic diagnosis and relabeling of the samples resulted in a much more pronounced separation of GIST and LMS in the MDS analysis. This study underscores the need to re-review histopathology as reclassification occurs. While updating the clinical database may be desired, this is usually impractical. For molecular studies that use archival samples, it is critical to have the archival samples re-reviewed by a pathologist. Further, unsupervised analysis often proves to be a critical quality control step in identifying structural problems that may exist. Finally, MDS analysis further supports that GIST is a distinct type of sarcoma.
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PMID:Unsupervised analysis uncovers changes in histopathologic diagnosis in supervised genomic studies. 1655 Nov 37

Systemic mastocytosis (SM) is characterized by the abnormal growth and accumulation of mast cells (MC) in one or more organs. The interaction between the cytokine stem cell factor (SCF) and its cognate receptor, the c-kit receptor tyrosine kinase (KIT), plays a central role in regulating MC growth and differentiation. Whereas germline and somatically acquired activating mutations of KIT have been identified in SM, the issue as to whether individual KIT mutation(s) are necessary and sufficient to cause MC transformation remains unclear based on currently available data. Activating mutations of platelet-derived growth factor receptor-alpha (FIP1 L1-PDGFRA) are identified in a significant number of SM cases that have associated eosinophilia. To date, as with gastrointestinal stromal tumors, activating mutations of KIT and PDGFRA appear to be alternative and mutually exclusive genetic events in SM. The World Health Organization has specified criteria for classification of SM into six major subtypes: cutaneous mastocytosis, indolent systemic mastocytosis (ISM), systemic mastocytosis with an associated clonal hematological non-mast-cell disorder (SM-AHNMD), aggressive systemic mastocytosis (ASM), mast cell leukemia, and mast cell sarcoma. The ability to molecularly classify individual SM cases based on the presence or absence of specific mutations allows for molecularly targeted therapy in a growing number of cases. Imatinib mesylate therapy might result in complete remission of SM cases with wild-type KIT, certain KIT mutations, such as F522C, or the FIP1L1-PDGFRA fusion gene, but not of D816V-KIT-bearing SM. For the latter, interferon-alpha and 2-CdA are potential first- and second-line therapeutic options. Other drugs under investigation include novel tyrosine kinase inhibitors, as well as NF-kappaB inhibitors, which might display greater selectivity towards D816V-KIT as compared to wild type KIT. The pathogenesis of mastocytosis, its major clinical subtypes, and recent treatment advances are discussed in this chapter.
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PMID:Pathogenesis, clinical features, and treatment advances in mastocytosis. 1678 90

We report a rare case of myeloid sarcoma (MS) of the extrahepatic bile ducts presenting as obstructive jaundice in a patient without leukemia at time of diagnosis. A 75-year-old female presented with a one-month history of abdominal pain and jaundice. Computerized tomography scan of the abdomen showed stenosis of the extrahepatic bile ducts. Endoscopic retrograde cholangiography disclosed an irregular narrowing of the common biliary duct, suggestive of a cholangiocarcinoma, and resection was performed. Histologic examination showed diffuse transmural infiltration of malignant cells. These cells exhibited medium-sized round nuclei with central nucleoli and eosinophilic cytoplasm, and were strongly positive for myeloperoxidase, CD68, lysozyme, CD45, CD117 (c-kit protein) and CD43. Eight months following surgery the patient presented with multiple cutaneous nodules and bone marrow trephine biopsy showed acute myelomonocytic leukemia. A literature search identified two previously reported cases of MS of the extrahepatic biliary duct. MS should be taken into consideration in the differential diagnosis of a patient with obstructive jaundice. Immunohistochemistry is essential for a correct diagnosis.
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PMID:Myeloid sarcoma of the extrahepatic bile ducts presenting as obstructive jaundice. 1694 23

Undifferentiated endometrial sarcoma (UES) is a high-grade sarcoma that lacks specific differentiation. Here, we present a unique case of UES that temporarily responded to imatinib mesylate. A 61-year-old woman presented with a pelvic mass, which rapidly increased in size over the course of 3 months. The mass in the hysterectomy specimen consisted of pleomorphic cells that did not show any endometrial stromal or smooth muscle differentiations; thus, the diagnosis of UES was made. Multiple regional recurrences around the urinary bladder were noted after 5 months, and treatment with imatinib mesylate was started, based on the provisional interpretation of KIT immunoreactivity on a biopsy specimen of the recurrent tumor. Two weeks later, the tumor shrunk significantly, as evaluated by computed tomography. However, they became enlarged under the therapy after 3 months since imatinib was first started. KIT immunohistochemical staining on the previously mentioned biopsy was reviewed thereafter, but it was not convincing. We also investigated for aberrations of c-kit and platelet-derived growth factor receptor alpha by polymerase chain reaction with direct sequencing, but no aberration was observed. Instead, focal but definite immunoreactivity to epidermal growth factor receptor (EGFR) was observed. In addition, EGFR gene amplification was confirmed by fluorescence in situ hybridization. We speculated that imatinib was temporarily effective on the clone with amplified EGFR, and that it became ineffective after this clone was eradicated. The amplified EGFR in UES has not been reported previously, and further studies are necessary to consider the possibility of EGFR-targeted therapy in such sarcomas.
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PMID:KIT-negative undifferentiated endometrial sarcoma with the amplified epidermal growth factor receptor gene showing a temporary response to imatinib mesylate. 1724 Mar 8

Gastro-intestinal stromal tumors (GIST), an abdominal sarcoma entity are characterized by a gain-of-function mutation in c-kit proto-oncogen (CD117). Initial treatment should aim at complete removal of the primary tumor (R0 resection) which almost never develops lymphatic metastases. Distant metastatic spread involves mainly the peritoneal cavity and the liver. In patients with metastatic disease, treatment with tyrosinkinase inhibitor imatinib mesylate (Glivec) is indicated and very effective. Systemic chemotherapy and external beam radiation must be considered ineffective. Patients requiring multivisceral resection to remove their primary tumor rapidly develop tumor recurrence and could potentially benefit from preoperative treatment with imatinib. Primary tumors are classified into four risk categories according to their size and mitotic activity. Whether there is an advantage of adjuvant treatment is currently under investigation within international randomized trials. Patients who develop an extensive remission of metastatic disease should be evaluated individually for resection of the tumor remnants. Even resection of single progressive lesions (with newly developed mutations) should be considered in carefully selected patients, if the remaining tumor can be controlled by continued imatinib treatment.
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PMID:[Gastrointestinal stromal tumors]. 1725 58

For the subgroup of patients with inoperable gastrointestinal stromal tumors, progress has been made by the rapid development and approval of the targeted therapy imatinib mesylate. Small round cell sarcoma, such as Ewing/PNET, desmoplastic small round cell sarcoma and rhabdomyosarcoma, are chemotherapy-sensitive and potentially curable malignancies, which are treated with multimodality, dose-intensitive and neoadjuvant protocols regardless of size or overt metastatic disease. A limited number of effective agents available for the treatment of patients with metastatic adult soft-tissue sarcoma exists, which have failed anthracyline and ifosfamide-based chemotherapy. Most other high-grade (grading >I) so-called adult-type soft-tissue sarcomas such as fibro, lipo, pleomorphic and synovial sarcoma are treated with a anthracycline-based regimen with or without ifosfamide as front-line therapy. In this review, the therapeutic activities of drugs currently available as second-line treatment in patients with metastatic soft tissue sarcoma are summarized, providing an overview of contentious or emerging treatment issues. In relapsed 'adult-type' soft-tissue sarcomas trofosfamide, gemcitabine and ecteinascidin (ET-743) appear to be drugs associated with moderate activity and an acceptable toxicity profile. An interesting finding to be noted is that the different drugs have particular effects in distinct subtypes of soft-tissue sarcoma; however, it has to be taken into account that the number of patients included in those phase II trials are limited. The role of the newer agents (e.g. patupilone derivates, brostallicin) is currently not definable. The so-called selective therapy targeting vascular endothelial growth factor (receptor), epidermal growth factor receptor, c-kit, Raf kinase or platelet-derived growth factor receptor and bcl-2 antisensing, proteasome, protein kinase C/B, and mammalian target of rabamycin inhibition will continue to be tested in gastrointestinal stromal tumors patients refractory to imatinib mesylate as well as in selected sarcoma subtypes.
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PMID:Systemic treatment options for patients with refractory adult-type sarcoma beyond anthracyclines. 1726 55


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