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:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The BCR/ABL tyrosine kinase inhibitor imatinib mesylate (Gleevec, STI571; Novartis, Basel, Switzerland) has shown remarkable efficacy in the treatment of chronic myelogenous leukemia (CML), with a high proportion of patients achieving complete cytogenetic responses (CCRs). However, it is not clear whether remissions will be durable and whether imatinib mesylate can eliminate the malignant primitive progenitors in which the disease arises. We investigated whether residual BCR/ABL+ hematopoietic progenitors were present in patients who achieved CCRs with imatinib mesylate treatment. CD34+ progenitor cells were selected from bone marrow mononuclear cells (MNCs) and analyzed for the presence of the BCR/ABL fusion gene by fluorescence in situ hybridization (FISH). CD34+ cells were also plated in committed progenitor (colony-forming cell, or CFC) and primitive progenitor (long-term bone marrow culture-initiating cell, or LTCIC) cultures and resulting colonies analyzed for the presence of BCR/ABL+ cells by FISH. Using these assays, residual BCR/ABL+ progenitors were detected in all patients studied. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis demonstrated increased levels of BCR/ABL mRNA in CD34+ cells compared with total MNCs. Evaluation of samples collected at different time points demonstrated persistence of BCR/ABL+ progenitors despite continued treatment with imatinib mesylate. Our results indicate that inhibition of BCR/ABL tyrosine kinase activity by imatinib mesylate does not eliminate malignant primitive progenitors in CML patients. Patients in CCR with imatinib mesylate treatment need to be followed carefully to assess for risk of relapse.
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PMID:Persistence of malignant hematopoietic progenitors in chronic myelogenous leukemia patients in complete cytogenetic remission following imatinib mesylate treatment. 1257 34

Receptor kinases play a key role in the communication of cells with their environment and could be important mediators of the effects of host cytokines on endoparasitic organisms. In this paper we describe, for the first time, the characterisation of a receptor tyrosine kinase of the insulin receptor family from a parasitic helminth. Using a degenerative PCR approach, we identified and completely characterised the 5.5kb coding DNA for an Echinococcus multilocularis factor (EmIR) which displays significant homologies to insulin receptors of different phylogenetic origin. EmIR exhibited a domain structure which is typical for the protein family and contained all catalytically important residues at corresponding positions. One striking difference between EmIR and known insulin receptors was the presence of a 172 amino acid insert in the tyrosine kinase region of, as yet, unknown function. In yeast two-hybrid analyses, the ligand binding domains of the human insulin receptor and of EmIR showed comparable affinity to human insulin. The EmIR encoding chromosomal locus (emir) was characterised and comprised 16.5kb. Southern blot hybridisations demonstrated that emir is present as a single copy locus in E. multilocularis. Furthermore, structural comparisons indicated that emir and the insulin receptor genes from mammals and insects derive from a common ancestor. Based on reverse transcriptase-polymerase chain reaction analyses, emir was found to be expressed in the two larval stages metacestode and protoscolex. EmIR is, therefore, likely to play an important role in echinococcal development and possibly also in the interaction with the mammalian host.
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PMID:Identification and molecular characterisation of a gene encoding a member of the insulin receptor family in Echinococcus multilocularis. 1267 May 15

Expression of ALK protein by lymphoid cells and the description of variant anaplastic lymphoma kinase (ALK) translocations have typically been restricted to cases of T-cell and null anaplastic large-cell lymphoma (ALCL). All such cases result from a novel fusion created by the ALK gene on chromosome 2p23 and NPM on 5q35 or other variant translocation partners. A rare variant of diffuse large B-cell lymphoma (DLBCL), originally described in 1997, was thought to overexpress full-length ALK in contrast to a chimeric protein characteristic of ALCL. However, full-length ALK protein lacks tyrosine kinase activity and thus the mechanism of oncogenesis has remained elusive. We describe 6 cases of ALK+ DLBCL characterized by a simple or complex t(2;17)(p23;q23) involving the clathrin gene (CLTC) at chromosome band 17q23 and the ALK gene at chromosome band 2p23. All cases were studied using fluorescence in situ hybridization (FISH), complemented in one case with standard cytogenetic analysis, multicolor karyotyping (M-FISH), and reverse transcriptase-polymerase chain reaction. These results clearly demonstrate that most cases of ALK+ DLBCL share the same mechanism of deregulated ALK expression. Moreover, these results demonstrate the presence of CLTC-ALK fusions in these tumors and extend the list of diseases associated with this genetic abnormality to include classical T-cell or null ALCL, ALK+ DLBCL, and inflammatory myofibroblastic tumors.
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PMID:ALK-positive diffuse large B-cell lymphoma is associated with Clathrin-ALK rearrangements: report of 6 cases. 1276 27

Human myometrial smooth muscle cells (SMCs) were used to evaluate the proliferative activity of lysophosphatidic acid (LPA). This study specifically focuses on the role of Ca(2+)/calmodulin-dependent protein (CaM) kinase and epidermal growth factor (EGF) receptor tyrosine kinase. Myometrial SMCs were cultured from biopsies taken at Cesarean sections. The expression of LPA receptors was determined by reverse transcriptase polymerase chain reaction (RT-PCR), and DNA-synthesis was measured by [3H]thymidine incorporation. LPA(1), LPA(2), and LPA(3)receptor subtypes were detected in the SMCs using RT-PCR. KN-62, an inhibitor of CaM kinase, and Tyrphostin AG 1478, an inhibitor of EGF receptor tyrosine kinase, dose-dependently decreased LPA-stimulated [3H]thymidine incorporation. Furthermore, BB-3103, an inhibitor of matrix metalloproteinases (MMPs), also reduced DNA-synthesis induced by LPA in these cells. The results show, for the first time, that human myometrial SMCs express all three known LPA receptor subtypes. Growth stimulatory effects of LPA on myometrial SMCs seems to be mediated by several pathways, where transactivation of EGF receptors through MMPs appears to be of importance. Furthermore, CaM kinase activity may be critical for LPA signaling since inhibition of CaM kinase totally abolish the proliferative effect of LPA.
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PMID:Inhibition of Ca2+/calmodulin-dependent protein kinase or epidermal growth factor receptor tyrosine kinase abolishes lysophosphatidic acid-mediated DNA-synthesis in human myometrial smooth muscle cells. 1278 50

Imatinib mesylate is effective in the treatment of hematologic malignancies that are characterized by either abl- or PDGFR beta- activating mutations. The drug is also active in a subset of patients with eosinophilic disorders and systemic mast cell disease (SMCD). Recently, a novel tyrosine kinase that is generated from fusion of the Fip1-like 1 (FIP1L1) and PDGFR alpha (PDGFRA) genes has been identified as a therapeutic target for imatinib mesylate in hypereosinophilic syndrome (HES). We used fluorescence in situ hybridization (FISH) to detect deletion of the CHIC2 locus at 4q12 as a surrogate for the FIP1L1-PDGFRA fusion. CHIC2 deletion was observed in bone marrow cells for 3 of 5 patients with SMCD associated with eosinophilia. Deletion of this locus and expression of the FIP1L1-platelet-derived growth factor receptor alpha (PDGFRA) fusion was also documented in enriched eosinophils, neutrophils, or mononuclear cells by both FISH and reverse transcriptase-polymerase chain reaction (RT-PCR) for one patient. While all 3 patients with the FIP1L1-PDGFRA rearrangement achieved a sustained complete response with imatinib mesylate therapy, the other two, both carrying the c-kit Asp816 to Val (Asp816Val) mutation, did not. These observations suggest that the FIP1L1-PDGFRA rearrangement occurs in an early hematopoietic progenitor and suggests that the molecular pathogenesis for a subset of SMCD patients is similar to that of HES. Screening for the FIP1L1-PDGFRA rearrangement and Asp816Val mutation will advance rational therapy decisions in SMCD.
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PMID:CHIC2 deletion, a surrogate for FIP1L1-PDGFRA fusion, occurs in systemic mastocytosis associated with eosinophilia and predicts response to imatinib mesylate therapy. 1284 79

Bruton's tyrosine kinase (BTK) is a cytoplasmic tyrosine kinase that serves an essential role in B cell signaling and development. We examined the BTK expression profile of primary leukemic cells from infants with newly diagnosed acute lymphoblastic leukemia (ALL) (N = 14) and from pediatric patients with newly diagnosed (N = 10) or relapsed (N = 5) B-lineage ALL. Analysis of BTK protein and mRNA expression in the infant patient cells (N = 14) showed variable levels of BTK expression with the majority of samples having reduced to absent BTK expression. Sequence analysis of reverse transcriptase-polymerase chain reaction (RT-PCR) products of Btk mRNA from infant leukemia cells revealed the presence of aberrant transcripts. These Btk transcripts were characterized by either deletion of exon 16 (delta16) alone or deletion of both exons 15 and 16 (delta15 and 16). These deletions involve exact exon skipping and encode BTK proteins with either a deleted (delta16), or truncated (delta15 and 16) kinase domain. Extension of these Btk transcript sequencing studies to 15 pediatric B-lineage ALL patients revealed expression of exon 16 deleted Btk transcripts in several pediatric patients, however, none of these pediatric patients expressed transcripts with the exon 15 and 16 deletion. Both reduced expression of Btk message and expression of aberrant deleted Btk transcripts would contribute to reduced BTK protein expression and function in B-lineage leukemia cells. Since BTK is required for radiation induced apoptosis, reduced to absent expression of functional BTK in infant ALL cells could contribute to their radiation resistance.
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PMID:Defective expression of Bruton's tyrosine kinase in acute lymphoblastic leukemia. 1285 3

Fibroblast growth factor receptor 3 (FGFR3) is one of four high-affinity tyrosine kinase receptors for the FGF family of ligands, frequently associated with growth arrest and induction of differentiation. The extracellular immunoglobulin (IgG)-like domains II and III are responsible for ligand binding; alternative usage of exons IIIb and IIIc of the Ig-like domain III determining the ligand-binding specificity of the receptor. By reverse transcriptase polymerase chain reaction (RT-PCR) a novel FGFR3IIIc variant FGFR3IIIS, expressed in a high proportion of tumours and tumour cell lines but rarely in normal tissues, has been identified. Unlike recently described nonsense transcripts of FGFR3, the coding region of FGFR3IIIS remains in-frame producing a novel protein. The protein product is coexpressed with FGFR3IIIc in the membrane and soluble cell fractions; expression in the soluble fraction is decreased after exposure to bFGF but not aFGF. Knockout of FGFR3IIIS using antisense has a growth-inhibitory effect in vitro, suggesting a dominant-negative function for FGFR3IIIS inhibiting FGFR3-induced growth arrest. In summary, alternative splicing of the FGFR3 Ig-domain III represents a mechanism for the generation of receptor diversity. FGFR3IIIS may regulate FGF and FGFR trafficking and function, possibly contributing to the development of a malignant phenotype.
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PMID:FGFR3IIIS: a novel soluble FGFR3 spliced variant that modulates growth is frequently expressed in tumour cells. 1452 Apr 60

Glial cell line-derived neurotrophic factor (GDNF) signals through multisubunit receptor complex consisting of RET tyrosine kinase and a glycosylphosphatidylinositol-anchored coreceptor called GDNF family receptor alpha1 (GFRalpha1). In the current study, we cloned a human SEP1 gene as a GDNF-inducible gene using human neuroblastoma cells that express RET and GFRalpha1. The induction of the SEP1 gene showed two peaks at 0.5-2 h and 24-48 h after GDNF stimulation by Northern blotting and quantitative real-time reverse transcriptase polymerase chain reaction. The late induction was also confirmed at protein levels by Western blotting with anti-SEP1 antibody. Immunostaining revealed that the expression of the SEP1 protein was detected in cell body, elongated neurites and growth cone-like structure of neuroblastoma cells treated with GDNF. In addition, we found a high level of SEP1 expression in neurons of the dorsal root and superior cervical ganglia and motor neurons of the spinal cord of mice in which RET is also expressed. SEP1 was co-immunoprecipitated with alpha- and beta-tubulins from the lysate of mouse brain. These results thus suggested that SEP1 is a GDNF-inducible and microtubule-associated protein that may play a role in the nervous system.
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PMID:Identification of human SEP1 as a glial cell line-derived neurotrophic factor-inducible protein and its expression in the nervous system. 1458 Sep 40

KIT (CD117), a tyrosine kinase receptor, has not been widely studied in epithelial tumours. In a systematic immunohistochemical survey of KIT expression on tissue arrays incorporating 671 cases, it was found that thymic carcinomas frequently express KIT. Twenty-two thymic carcinomas, 110 thymomas, and 16 non-neoplastic thymus glands were retrieved for further analyses. Immunohistochemically, 19 (86%) thymic carcinomas revealed heterogeneous to diffuse membranous positivity, whereas no thymomas or normal thymus glands contained positive epithelial cells. Using reverse transcriptase-polymerase chain reaction (RT-PCR), c-kit transcripts could be demonstrated in all immunohistochemically positive cases. PCR amplification and direct sequencing of the c-kit juxtamembrane domains (exons 9 and 11) and tyrosine kinase domain (exons 13 and 17) were also performed on the thymic carcinomas but mutations were not found. Some non-thymic epithelial tumours showed frequent KIT expression including adenoid cystic carcinomas of the salivary gland (100% positive), chromophobe renal cell carcinomas (94%), renal oncocytomas (67%), and neuroendocrine tumours (34%). Other carcinomas were infrequently immunoreactive for KIT. The findings of this study suggest that KIT is involved in the pathogenesis of thymic carcinomas. The overexpression of KIT in thymic carcinomas has potential diagnostic utility in differentiating these tumours from thymomas and carcinomas arising from other sites, which express KIT infrequently.
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PMID:KIT (CD117) is frequently overexpressed in thymic carcinomas but is absent in thymomas. 1499 4

Obstructive diseases of blood vessels and the lung are characterized by degradation and synthesis of new extracellular matrix (ECM) components. Regulated remodeling of the ECM in diseases such as atherosclerosis and lymphangioleiomyomatosis (LAM), both characterized by excessive accumulation of smooth muscle cells (SMCs), is thought to be controlled in part by cell surface receptors for specific ECM components. Discoidin domain receptors (DDR) 1 and 2 represent a family of tyrosine kinase collagen receptors that are activated by fibrillar collagens. To test the hypothesis that DDR may be involved in ECM remodeling by SMCs in vivo, we analyzed DDR expression by reverse transcriptase-polymerase chain reaction and immunohistochemistry and demonstrate that both DDR1 and DDR2 are up-regulated in nodules of LAM as compared to normal controls, and are expressed in lesions of atherosclerosis. In vitro, retroviral overexpression of DDR1 or DDR2 in human SMCs cultured on polymerized collagen gels leads to a reduction of collagen expression and induces matrix metalloproteinase (MMP) 1 at both mRNA and protein levels, but only DDR2 enhances MMP2 activation. Moreover, DDR2 overexpression increases SMC-mediated collagen and elastin degradation in vitro. Using laser microdissection, we extend our studies to the analysis of SMCs from LAM nodules where we observe higher MMP1 expression and MMP2 activation. Taken together, these data provide evidence for the potential roles of DDR1 and DDR2 in the regulation of collagen turnover mediated by SMCs in obstructive diseases of blood vessels and the lung.
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PMID:Role of discoidin domain receptors 1 and 2 in human smooth muscle cell-mediated collagen remodeling: potential implications in atherosclerosis and lymphangioleiomyomatosis. 1511 4


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