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)

Recurrent chromosome 12p deletions are associated with distinct tumor types and suggest the presence of a tumor suppressor gene (TSG). Previously, we mapped an EST with similarity to a protein tyrosine phosphatase to the minimally deleted region for all these neoplasms. The corresponding gene, DUSP16/MKP-7, was recently shown to code for a mitogen-activated protein kinase phosphatase, suggestive for a function as tumor suppressor. Overexpression of DUSP16 in BCR-ABL-transformed Rat-1 fibroblasts reduces their transforming capacity in vitro and in vivo via downregulation of BCR-ABL-induced JNK activation. A role for DUSP16 as a regulator of JNK signaling was further demonstrated via overexpression in Ba/F3 cells, which increased their antiapoptosis. However, no inactivating mutations could be detected in leukemia patients hemizygous for DUSP16, and the effect of hemizygosity on DUSP16 expression level could not be assessed due to the variability of DUSP16 transcript levels observed in leukaemia cell lines and in patients. Taken together, the functional data point to a context-dependent role for DUSP16 on cell transformation and apoptosis, reflecting the dual role of JNK, and therefore suggest that DUSP16 might be haploinsufficient for tumor suppression.
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PMID:MAPK phosphatase DUSP16/MKP-7, a candidate tumor suppressor for chromosome region 12p12-13, reduces BCR-ABL-induced transformation. 1458 99

Imatinib mesylate (IM) binds to the BCR-ABL protein, inhibiting its kinase activity and effectively controlling diseases driven by this kinase. IM resistance has been associated with kinase mutations or increased BCR-ABL expression. However, disease progression may be mediated by other mechanisms that render tumor cells independent of BCR-ABL. To demonstrate this potential, IM-resistant cells were found in chronic myelogenous leukemia patients with continuous BCR-ABL gene expression but undetectable BCR-ABL protein expression. These cells were unresponsive to IM and acquired BCR-ABL-independent signaling characteristics. IM resistance in some patients may be mediated through loss of kinase target dependence.
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PMID:Imatinib mesylate resistance through BCR-ABL independence in chronic myelogenous leukemia. 1474 84

KIT and platelet-derived growth factor receptors (PDGFRs) play critical oncogenic roles in a broad spectrum of hematologic and solid tumors. These receptor tyrosine kinases, as well as ABL and BCR-ABL, are inhibited by imatinib. Tumors caused by chromosomal translocations that lead to overexpression of PDGFR ligand, resulting in continuous activation of wild-type PDGFRs, are likely to respond to imatinib, as are malignancies caused by gene amplification and overexpression of wild-type PDGFR or KIT receptors. Malignancies linked to chromosomal translocations that express PDGFR or KIT fusion protein-tyrosine kinases are also likely to respond to imatinib. Malignant cell responses to imatinib depend on whether any of these tyrosine kinase activities play essential roles in the oncogenesis of a given tumor, as well as the precise molecular mechanism underlying oncogenesis. For example, imatinib efficacy for malignancies arising from constitutively activating point mutations in tyrosine kinases depends on the exact location of the mutation in the kinase molecule.
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PMID:Role of KIT and platelet-derived growth factor receptors as oncoproteins. 1517 98

Solid malignancies often exhibit high interstitial fluid pressure (IFP), which causes poor uptake of anticancer drugs. While there are several mechanisms that regulate IFP in tumors, activation of platelet-derived growth factor receptor, which is expressed in various cell types within the tumor microenvironment, has been observed to play an important role in elevating IFP. In preclinical studies, treatment with imatinib, which inhibits both alpha- and beta-platelet-derived growth factor receptors, as well as KIT, ABL, ARG, and BCR-ABL tyrosine kinases, has been shown to decrease tumor IFP and concomitantly augment uptake of chemotherapeutic drugs, thereby enhancing the efficacy of chemotherapy. This review discusses preclinical studies showing the ability of imatinib to lower IFP and increase drug uptake within solid tumors, as well as the scientific rationale for clinical use of imatinib as combination therapy for chemotherapy.
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PMID:Increasing tumor uptake of anticancer drugs with imatinib. 1517

Imatinib mesylate (Gleevec/Glivec, Novartis, Basel, Switzerland), formerly called STI571, is a specific and potent inhibitor of the BCR-ABL tyrosine kinase, the molecular hallmark of chronic myeloid leukaemia. Several clinical trials have demonstrated the efficacy of imatinib in different phases of this disease. On the other hand, imatinib is also active against other tyrosine kinases, such as ABL, the stem cell factor receptor (c-kit) and the platelet-derived growth factor receptor, whose inhibition might have potential implications for the treatment of several malignancies. In this regard, imatinib has already shown a remarkable activity in patients with hypereosinophilic syndrome and gastrointestinal stromal tumours. Imatinib is an example of how a better understanding of the pathogenetic mechanisms of a neoplastic disease can lead to the development of a molecular-targeted therapy.
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PMID:Imatinib mesylate (Gleevec/Glivec) a molecular-targeted therapy for chronic myeloid leukaemia and other malignancies. 1520 9

The chromosomal translocation t,(9;22) resulting in the fusion of the BCR and ABL1 genes, represents a recurrent aberration in B cell precursor leukemia cells. Their normal counterparts, B cell precursor cells, are positively selected for survival signals through the antigen receptor, whose expression requires a functional immunoglobulin heavy chain (IGH) gene rearrangement. Unexpectedly, B cell precursor leukemia cells harboring a BCR-ABL1 gene rearrangement do not depend on antigen receptor mediated survival signals. Genes involved in the signaling cascade of the antigen receptor are silenced and in most cases, the dominant tumor clone does not carry a functional IGH gene rearrangement. However, upon inhibition of the BCR-ABL1 kinase activity by STI571, only leukemia cells expressing an antigen receptor are able to survive. Since resistance to STI571 is frequent in the therapy of BCR-ABL1(+) B cell precursor leukemia, antigen receptor signaling may represent a mechanism through which these cells can temporarily evade STI571-induced apoptosis. This may open a time frame, during which leukemia cells acquire secondary transforming events that confer definitive resistance to STI571.
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PMID:Interference of BCR-ABL1 kinase activity with antigen receptor signaling in B cell precursor leukemia cells. 1525 1

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

Epidermal growth factor (EGF) and its cognate receptor (EGF-R) are often dysregulated in human neoplasia. Moreover, EGF-R-transformed cell lines have constitutive EGF-R activity, which makes elucidation of its effects difficult to determine. In the following studies, the effects of a novel conditionally activated form of EGF-R, v-ErbB:ER, on the morphological transformation of NIH-3T3 cells and the abrogation of hematopoietic cell cytokine dependence were investigated. The v-ErbB ES-4 oncogene was fused to the hormone binding domain of the estrogen receptor (ER). This construct, v-ErbB:ER, requires beta-estradiol or 4-OH tamoxifen for activation. v-ErbB:ER conditionally transformed NIH-3T3 cells and abrogated cytokine dependence of hematopoietic cells. Stimulation of v-ErbB:ER activity resulted in the activation of the phosphatidylinositol 3-kinase (PI3K)/Akt and Raf/MEK/ERK kinase cascades. To determine the importance of these signal transduction pathways, the conditionally transformed hematopoietic cells were treated with EGF-R, PI3K and MEK inhibitors. The EGF-R inhibitor AG1478 effectively inhibited MEK, ERK and Akt activation, and induced apoptosis when the cells were grown in response to v-ErbB:ER. Apoptosis was observed at 100- to 1000-fold lower concentrations of AG1478 when the cells were grown in response to v-ErbB:ER as opposed to IL-3. Furthermore, the parental, BCR-ABL- and Raf-transformed cells were only susceptible to the apoptosis-inducing effects of AG1478 at the highest concentrations demonstrating the specificity of these inhibitors. MEK or PI3K inhibitors suppressed ERK or Akt activation, respectively, and induced apoptosis in the v-ErbB:ER-responsive cells. However, MEK and PI3K inhibitors only induced apoptosis at 1000-fold higher concentrations than the EGFR inhibitor. This novel v-ErbB:ER construct and these conditionally transformed cell lines will be useful to further elucidate ErbB-mediated signal transduction and to determine the effectiveness of various inhibitors in targeting different aspects of EGF-R-mediated signal transduction and malignant transformation.
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PMID:Effects of a conditionally active v-ErbB and an EGF-R inhibitor on transformation of NIH-3T3 cells and abrogation of cytokine dependency of hematopoietic cells. 1536 36

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

Chronic myeloid leukemia (CML) is sustained by a rare population of primitive, quiescent, BCR-ABL+ cells and represents an excellent example of a malignancy in which tumor-initiating cells represent the key to disease eradication. CML is also the first malignancy for which targeted therapy has replaced conventional chemotherapy. Within a vast excess of proliferating progenitor cells that express breakpoint cluster region-abelson (BCR-ABL) and are exquisitely sensitive to the tyrosine kinase inhibitor imatinib mesylate (IM) resides a small population of quiescent leukemic cells that, despite higher levels of BCR-ABL transcripts, exhibits innate insensitivity to IM. These cells remain after IM therapy, even when apparently complete responses are achieved, and they probably explain molecular disease persistence. Although it can be argued that patients may survive for many years with low levels of leukemia still present, it is possible to achieve disease clearance at the molecular level following an allogeneic stem cell transplantation. The emergence of drug resistance with IM monotherapy also argues in favor of complete disease eradication that we believe should remain the ultimate therapeutic goal in CML. New approaches to the elimination of these primitive CML cells may thus be crucial to the development of curative strategies.
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PMID:Punish the parent not the progeny. 1552 14


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