Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

PDGFs and their cognate tyrosine kinase alpha- and beta-receptors are involved in multiple tumor-associated processes including autocrine growth stimulation of tumor cells, stimulation of tumor angiogenesis and recruitment and regulation of tumor fibroblasts. The recent development of clinically useful PDGF antagonists, like STI571/Glivec, has increased the interest in PDGF receptors as cancer drug targets. Autocrine PDGF receptor signaling occurs in certain malignancies characterized by mutational activation of PDGF or PDGF receptors, for instance, dermatofibrosaracoma protuberans, gastrointestinal stromal tumors, and hypereosinophilic syndrome. The roles of PDGF in regulation of tumor angiogenesis and tumor fibroblasts are more general, and probably occur in most common solid tumors. Concerning tumor angiogenesis recent studies have predominantly focused on the importance of PDGF receptor signaling for tumor pericyte recruitment. PDGF receptors in the tumor stroma have also attracted attention as interesting drug targets because of their function as regulators of tumor interstitial fluid pressure, tumor transvascular transport and tumor drug uptake. In summary, the improved understanding of the role of PDGF signaling in tumor biology, and the introduction of PDGF antagonists, has set the stage for a continued development of PDGF antagonists as novel cancer drugs.
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PMID:PDGF receptors-mediators of autocrine tumor growth and regulators of tumor vasculature and stroma. 1520 17

Resistance to the ABL kinase inhibitor imatinib (STI571 or Gleevec) in chronic myeloid leukemia (CML) occurs through selection for tumor cells harboring BCR-ABL kinase domain point mutations that interfere with drug binding. Crystallographic studies predict that most imatinib-resistant mutants should remain sensitive to inhibitors that bind ABL with less stringent conformational requirements. BMS-354825 is an orally bioavailable ABL kinase inhibitor with two-log increased potency relative to imatinib that retains activity against 14 of 15 imatinib-resistant BCR-ABL mutants. BMS-354825 prolongs survival of mice with BCR-ABL-driven disease and inhibits proliferation of BCR-ABL-positive bone marrow progenitor cells from patients with imatinib-sensitive and imatinib-resistant CML. These data illustrate how molecular insight into kinase inhibitor resistance can guide the design of second-generation targeted therapies.
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PMID:Overriding imatinib resistance with a novel ABL kinase inhibitor. 1525 43

Genetic mutations can lead to abnormal activation of certain kinases that in turn lead to excessive cell division seen in cancers. Inhibitors of over activated kinases can theoretically inhibit cancer causing pathways and result in tumor shrinkage. These discoveries have sparked a revolution in drug discovery with many small molecule kinases inhibitors now being used in cancer clinical trials. The amazing success of Imatinib, a blocker of the bcr-abl kinase in chronic myeloid leukemia has shown that the drugs based on these strategies can improve cure rates in cancer. In this article, the authors review the concepts of kinase inhibition in cancer and principles behind the success of imitanib. The authors also review other promising kinase inhibitors being used in clinical trials that are expected to aid the fight against cancer.
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PMID:Kinase inhibitors translate lab discoveries into exciting new cures for cancers. 1534 72

Recent data suggest that STI571 (Imatinib) induces complete cytogenetic responses in patients with chronic myeloid leukemia (CML) who relapse after allogeneic stem cell transplantation (SCT). However, little is known about molecular responses to STI571 and the duration of leukemia-free survival in these patients. We report on a 43 year old female patient who presented with a relapse from Ph+ CML in December 2000. Five years earlier she had received an SCT from an unrelated male donor in accelerated phase. At the time of relapse, she presented with marked leukocytosis (89,000 microl) and 10% blasts. In December 2000, therapy with Imatinib was started. After 3 months, the karyotype showed an XY, with trisomy 8 in about 50% of all metaphases, but without evidence of residual Ph+ cells. Moreover, in response to Imatinib, BCR/ABL transcripts decreased and were no longer detectable after 6 months. After a total observation period of 36 months, the patient is still in complete cytogenetic and molecular remission without signs of occurrence of a donor-type hematopoietic neoplasm or CML relapse. These data suggest that Imatinib is a useful agent for long term treatment of relapsed CML after allogeneic SCT.
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PMID:Detection of trisomy 8 in donor-derived Ph- cells in a patient with Ph+ chronic myeloid leukemia successfully treated with Imatinib (STI571) in relapse after allogeneic transplantation. 1535 47

Pulmonary leukostasis is a rare but serious and often fatal complication of chronic myeloid leukemia (CML) in blast crisis and acute myeloid leukemia. Treatment options are limited for these patients. Imatinib mesylate (STI-571, Gleevec, Novartis) is a potent and selective inhibitor of the BCR-abl tyrosine kinase, the molecular abnormality that causes CML. The case of a 74-year-old man with a history of CML who presented in myeloid blast crisis with pulmonary leukostasis characterized by increasing dyspnea, hypoxemia, fever, and impending respiratory failure is reported. The patient was treated with single agent imatinib mesylate (IM) with rapid decrease in his white blood cell count (WBC) and marked improvement in his respiratory status. No electrolyte abnormalities consistent with tumor lysis syndrome were observed. IM may be an effective single agent therapy for pulmonary leukostasis in patients with CML blast crisis who are at the risk for tumor lysis.
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PMID:Management of life-threatening pulmonary leukostasis with single agent imatinib mesylate during CML myeloid blast crisis. 1537 82

Ewing sarcoma is a small round blue cell tumor with a high incidence of metastasis and poor survival. The tyrosine kinase receptor, c-kit, is a growth factor receptor that is expressed in a variety of tumors including Ewing sarcoma. Blockade of c-kit by imatinib mesylate (Gleevec; Novartis Pharmaceuticals Corp, East Hanover, NJ) has been successfully used in the treatment of chronic myelogenous leukemia and gastrointestinal tumors. Detection of c-kit expression in Ewing sarcoma indicates a possible role of c-kit in tumor progression and a potential use of anti-c-kit therapy in Ewing sarcoma. Ki-67 is a proliferation marker found at all stages of the cell cycle. Expression of c-kit and Ki-67 was studied in 17 patients with Ewing sarcoma. Sections from paraffin-embedded tumor samples were immunostained, using standard immunohistochemical protocols, with c-kit and Ki-67 monoclonal antibodies, polyclonal c-kit antibody without antigen retrieval, and c-kit polyclonal antibody with antigen retrieval. Eleven out of 17 cases (65%) stained with c-kit monoclonal antibody; the staining was diffuse in 6/17 (35%) cases. C-kit expression did not correlate with Ki-67 proliferation rates. Using the polyclonal c-kit-antibody without antigen retrieval methods, c-kit expression was demonstrated in 1/11 (9%) cases. Incorporating antigen retrieval methods, c-kit expression increased to 53%. Concordance between monoclonal antibodies in detecting c-kit expression was observed in 12/17 cases (71%). We conclude that c-kit is variably expressed in Ewing sarcoma, using either monoclonal or polyclonal antibodies. Detection of c-kit expression in Ewing sarcoma improves with the use of antigen retrieval methods.
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PMID:Expression of c-kit in Ewing family of tumors: a comparison of different immunohistochemical protocols. 1538 30

We report a 59-year-old man with chronic myelogenous leukemia (CML) in chronic phase who presented with a large abdominal tumor. Biopsy revealed proliferation of granulocytic-, erythroid-, and megakaryocytic-lineage cells in a retroperitoneal lymph node. The BCR/ABL fusion gene was detected on a paraffin-embedded tissue section of the lymph node by double-color fluorescence in situ hybridization, indicating an extramedullary hematopoietic tumor of CML origin. This patient has achieved a complete cytogenetic response for 19 months with imatinib mesylate (STI571; Gleevec), in association with the regression of the tumor. However, the development of an extramedullary tumor in chronic-phase CML generally indicates a poor prognosis, because it commonly consists of blast proliferation and is followed by blast crisis in the marrow within a few months. This case, therefore, points to the importance of histological examination of extramedullary tumors in CML for evaluation of disease status and for therapeutic decisions.
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PMID:Case of chronic-phase chronic myelogenous leukemia with an abdominal hematopoietic tumor of leukemic clone origin. 1538 5

To identify markers sensitive to inhibitors of the farnesylation pathway, we used 3 breast cancer cell lines (SKBR-3, MDA-175, and MDA-231) to evaluate the in vitro effects of pamidronate, an inhibitor of farnesyl diphosphate synthase. In response to pamidronate, there was significant inhibition of cell proliferation in MDA-231 and SKBR-3 cells, compared to MDA-175 cells. This correlated with their respective basal levels of N-ras and H-ras. N-ras and H-ras protein levels were both reduced in MDA-231 cells, and to lesser extent in SKBR-3 cells, following exposure to pamidronate, whereas these markers were not altered in MDA-175 cells. Combinatorial therapy with pamidronate and Gleevec, an inhibitor of several tyrosine kinases; Velcade, a proteasome inhibitor; or rapamycin, an inhibitor of the mammalian target of rapamycin (m-TOR) all showed additive effects in causing proliferative inhibition in MDA-175 cells. In summary, resistance to pamidronate may result from low levels of GTPase-activating proteins, such as N-ras and H-ras, in tumor cells. Combinatorial therapies directed against other signaling pathways, not dependent upon ras, may be required to overcome such resistance.
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PMID:Pamidronate resistance and associated low ras levels in breast cancer cells: a role for combinatorial therapy. 1548

Most gastrointestinal stromal tumors (GISTs) harbor oncogenic mutations in the KIT gene, and the majority of these mutations affect the juxtamembrane domain of the kinase encoded by exon 11. Screening GISTs for KIT gene mutations is important for translational research studies and for providing prognostic information on the likelihood of tumor response to treatment with the kinase inhibitor imatinib mesylate (Gleevec). In a series of GISTs analyzed in our laboratory by a combination of denaturing HPLC and direct DNA sequencing, we identified 19 cases with KIT exon 11 deletions that included from 1 to 14 bp of intron 10 sequence and resulted in loss of the normal splice acceptor site at the beginning of exon 11. Predicted use of the next potential splice-acceptor site was confirmed by cDNA sequencing in 4 cases. Thus, the resulting mutant isoform, deletion KPMYEVQWK 550-558, was the same in all 19 cases. Only two other examples of deletions across the intron 10-exon 11 boundary have been reported, yet among 722 GISTs analyzed in our laboratories these deletions were not uncommon, accounting for 3.9% of exon 11 mutations and 2.6% of all tumors. Loss of KIT intron 10 sequences may be under-recognized if the forward primer is too close to exon 11, or if cases are examined exclusively at the cDNA level. Laboratories that offer clinical screening for KIT mutations in GI stromal tumors should be aware of this class of mutations.
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PMID:KIT gene deletions at the intron 10-exon 11 boundary in GI stromal tumors. 1550 76

Small cell lung cancer (SCLC) is an aggressive type of lung cancer, for which cytotoxic chemotherapy appears to have reached its maximal efficacy. This neoplasm is characterized by the overexpression of several receptor tyrosine kinases (RTKs), especially c-Kit. The ligand for c-Kit is stem cell factor (SCF). In SCLC, SCF can influence c-Kit activation by autocrine or paracrine mechanisms. We have recently shown that the c-Kit/SCF pathway is operational in SCLC and can be inhibited by Glivec (STI571). Because the inhibition of topoisomerase-I (topo-I) is one approach used to treat SCLC, we determined the effects of c-Kit/SCF signaling on topo-I activity. A unique phosphorylation of c-Kit on amino acid 823 and amino acid 703 was identified with the SCF stimulation of H526 cells. We demonstrate that with SCF stimulation over 16 hours (dose response 0-100 ng/mL) in H526 SCLC cells (c-Kit positive, SCF responsive), a decrease in topo-I activity was observed, whereas in H82 SCLC cells (c-Kit negative, SCF unresponsive) there was no modulation of topo-I activity by SCF. Using STI571 (5 microM, 16 hours) to inhibit the c-Kit pathway following stimulation with SCF (100 ng/mL), an upregulation of topo-I activity was observed in H526 cells but not in H82 cells. Performing viability assays, we show that STI571 in combination with topo-I inhibition by camptothecin or SN38, the active metabolite of irinotecan, can cooperatively inhibit H526 cell viability (but not H82 cell viability) for 72 hours. We also show that STI571 does not directly inhibit topo-I activity in SCLC. The combination of STI571 with topo-I inhibition could provide a useful combination in the treatment of SCLC.
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PMID:Modulation of c-Kit/SCF pathway leads to alterations in topoisomerase-I activity in small cell lung cancer. 1551 Dec 12


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