Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0079731 (B-cell lymphoma)
 16,671 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In human T cells CD45 is reported to associate with both cell surface and intracellular molecules including CD2, CD4/CD8, CD5, p56lck and p59fyn. In this study the association of molecules with CD45 in murine T lymphocytes was explored using biotinylation, chemical cross-linking, immunoprecipitation and 32P-labelling. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of CD45 monoclonal antibody (mAb) (S-450-15.2) immunoprecipitates from Triton X-100 lysates of murine thymocytes that were surface biotinylated and treated with the chemical cross-linker 3,3'-dithio-bis(sulpho-succinimidylpropionate) (DTSSP) showed that CD45 can be chemically linked to molecules of 25,000-32,000, 42,000 and 60,000-70,000 MW. The CD45 mAb also co-precipitated a prominent 32,000 MW molecule from digitonin lysates of surface biotinylated murine thymocytes, splenocytes and D10 cells, but a weaker association was also detected on splenic B cells and on the murine B-cell lymphoma line A20. The results suggest that in these cells CD45 is associated with a 32,000 MW molecule which is exposed extracellularly. Experiments in which thymocytes were biotinylated after permeabilization with lysolecithin showed that additional molecules of 33,000, 55,000, 60,000 and 90,000 MW, presumably localized intracellularly, also co-precipitated with CD45. Labelling of murine thymocytes or D10 cells with H3(32)PO4 in vivo, and of CD45 immunoprecipitates by in vitro kinase reaction, revealed that the 32,000-33,000 MW molecules are phosphoproteins. The relationship of these molecules with the 30,000-34,000 MW molecules previously reported to associate with CD45 in human T cells is not clear as a number of differences were observed. Firstly, the molecular weight of the CD45-associated 32,000-33,000 MW molecule(s) on murine T cells and B cells is slightly lower than that observed in the human T-cell line Jurkat (34,000 MW). Secondly, phosphoamino acid analysis after in vitro kinase labelling of CD45 immunoprecipitates showed that the murine 32,000-33,000 MW molecules are phosphorylated exclusively on serines. Thirdly, although in vitro phosphorylation of the 32,000-33,000 MW molecules was inhibited by preincubation with either GTP-gamma-S or GDP-beta-S, the 32,000-33,000 MW CD45-associated molecules did not bind 32P-GTP, GDP-agarose, or react with antisera to a consensus sequence of G proteins. The crucial role of CD45 for proper function of the T-cell receptor (TCR), suggests that the CD45-associated 32,000-33,000 MW molecules and kinases also may play a role in the signalling events leading to T-cell activation.
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PMID:Evidence for an association of CD45 with 32,000-33,000 MW phosphoproteins on murine T and B lymphocytes. 783 67

Guanylate kinase catalyzes the phosphorylation of either GMP to GDP or dGMP to dGDP and is an essential enzyme in nucleotide metabolism pathways. Despite its involvement in antiviral drug activation in humans and in mouse model systems and as a target for chemotherapy, the human and mouse primary structures have never been elucidated. Full-length cDNA clones encoding enzymatically active guanylate kinase were isolated from mouse B-cell lymphoma and human peripheral blood lymphocyte cDNA libraries. Multiple tissue Northern blots demonstrated an mRNA species of approximately 1 kilobase for both mice and humans in all tissue types examined. The mouse cDNA is predicted to encode a 198-amino acid protein with a molecular mass of 21,904 daltons. The human cDNA is predicted to encode a 197-amino acid protein with a molecular mass of 21,696 daltons. These proteins share 88% sequence identity with each other and 52-54% identity with the yeast guanylate kinase. Molecular modeling using the yeast diffraction coordinates indicates a high degree of conservation within the active site and maintenance of the overall structural integrity, despite a lack of similarity along the periphery of the enzyme.
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PMID:Cloning, characterization, and modeling of mouse and human guanylate kinases. 866 13

The human alpha1,3-fucosyltransferase, Fuc-TVII, a key enzyme in the biosynthesis of selectin ligands, was expressed as a soluble protein-A chimeric form in a human B cell lymphoma cell line, Namalwa KJM-1, and purified using IgG-Sepharose. The enzymatic properties of recombinant soluble Fuc-TVII were then examined. Its enzyme activity was highest at pH 7.5, and the presence of 25 mM Mn2+ was required for full activity. Fuc-TVII exhibits an acceptor specificity restricted to alpha2,3-sialylated type 2 oligosaccharides, and the apparent Km values for alpha2,3-sialyl lacto-N-neotetraose and GDP-fucose were 3.08 mM and 16.4 microM, respectively. The inhibitory effects of various nucleotides on the activity of Fuc-TVII reflected its donor specificity for the nucleotide portion of GDP. Fuc-TVII was demonstrated to be useful for the synthesis of a sialyl Lewis x hexasaccharide from lacto-N-neotetraose in combination with an alpha2, 3-sialyltransferase, ST3Gal IV. Polyethylene glycols enhanced the thermal stability of Fuc-TVII, leading to increased formation of the reaction product.
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PMID:Enzymatic characterization of human alpha1,3-fucosyltransferase Fuc-TVII synthesized in a B cell lymphoma cell line. 940 91

The Cool-2 (cloned-out of library-2) protein (identical to alpha-Pix for Pak-interactive exchange factor) has been implicated in various biological responses including chemoattractant signaling and in certain forms of mental retardation. We show that when Cool-2 exists as a dimer, it functions as a Rac-specific guanine nucleotide exchange factor (GEF). Dimerization of Cool-2 enables its Dbl (diffuse B-cell lymphoma) and pleckstrin homology domains to work together (in trans) to bind specifically to Rac-GDP. Dissociation of dimeric Cool-2 into its monomeric form allows it to act as a GEF for Cdc42 as well as for Rac. The binding of either PAK (p21-activated kinase) or Cbl (Casitas B-lymphoma) to the SH3 domain of monomeric Cool-2 is necessary for the functional interactions between GDP-bound Cdc42 or Rac and the Cool-2 monomer. The betagamma subunit complex of large GTP-binding proteins, by interacting with PAK, stimulates the dissociation of the Cool-2 dimer and activates its GEF activity for Cdc42. Overall, these findings highlight novel mechanisms by which extracellular signals can direct the specific activation of Rac versus Cdc42 by Cool-2/alpha-Pix.
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PMID:Novel regulatory mechanisms for the Dbl family guanine nucleotide exchange factor Cool-2/alpha-Pix. 1530 50

The small GTPase Cdc42 has been implicated in a number of cellular responses ranging from the regulation of the actin cytoskeletal architecture to intracellular trafficking and cell cycle progression. Cdc42 mutants that constitutively exchange GDP for GTP but still hydrolyze GTP (called 'fast-cycling' mutants) promote cellular transformation, whereas Cdc42 mutants that are unable to hydrolyze GTP and are irreversibly trapped in the GTP-bound state often inhibit cell growth. In this work, we have set out to further establish that Cdc42 needs to cycle between its 'on' and 'off' states to stimulate cell growth, by examining the consequences of manipulating its GTP-binding/GTP hydrolytic cycle in two different ways. One approach was to examine whether substitutions that act in a manner opposite to the 'fast cyclers', and extend the lifetime of the activated GTP-bound state by slowing the GTP hydrolytic reaction (i.e., 'slow-cycling' mutations), positively influence cell growth. Indeed we show that one such slow-cycling mutant, Cdc42[Y32A], which is insensitive to Cdc42GAP but still exhibits a measurable intrinsic GTP hydrolytic activity, gives rise to increased levels of activated Cdc42 in NIH 3T3 cells. We go on to show that the Y32A mutant stimulates the actin cytoskeletal changes that lead to filopodia formation, confer growth advantages to fibroblasts under low serum conditions, and enable cells to grow to high densities when exposed to normal levels of serum. The second approach was to determine whether the transforming activity of the fast-cycling Cdc42[F28L] mutant can be reversed by compensating for its accelerated nucleotide exchange reaction through the expression of the GTPase-activating protein (Cdc42GAP) and the ensuing stimulation of GTP hydrolytic activity. We showed that expression of the limit functional domain of Cdc42GAP inhibited Cdc42[F28L]-induced transformation, as well as selectively reversed the transformed phenotypes caused by the hyperactivation of wild-type Cdc42 in cells expressing the oncogenic version of Dbl (for Diffuse B cell lymphoma), a guanine nucleotide exchange factor for Cdc42 and the related Rac and Rho GTPases. Overall, the results reported here establish the requirement for Cdc42 to cycle between its signaling-on and -off states in order to positively influence cell growth and highlight how the Cdc42GAP can play an important role in regulating cell proliferation.
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PMID:Influencing cellular transformation by modulating the rates of GTP hydrolysis by Cdc42. 1678 26

HGAL is a germinal center (GC)-specific gene that negatively regulates lymphocyte motility and whose expression predicts improved survival of patients with diffuse large B-cell lymphoma (DLBCL) and classical Hodgkin lymphoma (cHL). We demonstrate that HGAL serves as a regulator of the RhoA signaling pathway. HGAL enhances activation of RhoA and its down-stream effectors by a novel mechanism - direct binding to the catalytic DH-domain of the RhoA-specific guanine nucleotide exchange factors (RhoGEFs) PDZ-RhoGEF and LARG that stimulate the GDP-GTP exchange rate of RhoA. We delineate the structural domain of HGAL that mediates its interaction with the PDZ-RhoGEF protein. These observations reveal a novel molecular mechanism underlying the inhibitory effects of GC-specific HGAL protein on the motility of GC-derived lymphoma cells. This mechanism may underlie the limited dissemination and better outcome of patients with HGAL-expressing DLBCL and cHL.
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PMID:HGAL, a germinal center specific protein, decreases lymphoma cell motility by modulation of the RhoA signaling pathway. 2084 36

Dbl is the prototype of a large family of GDP-GTP exchange factors for small GTPases of the Rho family. In vitro, Dbl is known to activate Rho, Rac, and Cdc42 and to induce a transformed phenotype in murine fibroblasts. We previously reported that Dbl-null mice are viable and fertile but display defective dendrite elongation of distinct subpopulations of cortical neurons, suggesting a role of Dbl in controlling dendritic growth. To gain deeper insights into the role of Dbl in development and disease, we attempted a knock-in approach to create an endogenous allele that encodes a missense-mutation-mediated loss of function in the DH domain. We generated, by gene targeting technology, a mutant mouse strain by inserting a mutagenized human proto-Dbl cDNA clone expressing only the Dbl N terminus regulatory sequence at the starting codon of murine exon 1. Animals were monitored over a 21-month period, and necropsy specimens were collected for histological examination and immunohistochemistry analysis. Dbl knock-in mice are viable and did not manifest either decreased reproductive performances or gross developmental phenotype but revealed a reduced lifespan compared to wild-type (w.t.) mice and showed, with aging, a B cell lymphoproliferation that often has features of a frank diffuse large B cell lymphoma. Moreover, Dbl knock-in male mice displayed an increased incidence of lung adenoma compared to w.t. mice. These data indicate that Dbl is a tumor susceptibility gene in mice and that loss of function of Dbl DH domain by genetic missense mutations is responsible for induction of diffuse large B cell lymphoma.
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PMID:High frequency of development of B cell lymphoproliferation and diffuse large B cell lymphoma in Dbl knock-in mice. 2122 14

Patients with primary refractory diffuse large B-cell lymphoma (REF DLBCL: progression on or within 3 months of completion of primary therapy) sensitive to salvage chemotherapy undergo autologous stem cell transplant (ASCT). We conducted a retrospective review of 111 patients with REF DLBCL treated between 1999 and 2007. Primary treatment consisted of cyclophosphamide, adriamycin, vincristine and prednisone (CHOP; 66%) and rituximab with CHOP (R-CHOP; 33%); 14% received involved field radiation. The response rate (RR) to first salvage chemotherapy was 23% (RR by regimen: dexamethasone, cytosine arabinoside and cisplatin [DHAP] 15%, etoposide, Solu-Medrol, cytosine arabinoside and cisplatin [ESHAP] 36%, and gemcitabine, dexamethasone and cisplatin [GDP] 45%); 25% (n = 28) of patients underwent ASCT. With a median follow-up of 5.9 months (range 1-94), the median progression-free and overall survival from primary treatment failure was 3 and 10 months, respectively. Outcomes in patients with REF DLBCL after CHOP or R-CHOP appear equally poor. Second-generation platinum-containing regimens (ESHAP, GDP) may be superior to DHAP in this setting. Novel, prospectively evaluated treatment approaches should be pursued in REF DLBCL.
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PMID:Salvage chemotherapy and autologous stem cell transplant in primary refractory diffuse large B-cell lymphoma: outcomes and prognostic factors. 2218 38

This study was conducted to evaluate the efficacy and safety of Rituximab, Gemcitabine, Cisplatin, and Dexamethasone (R-GDP) in relapsed or refractory aggressive B-Cell Non-Hodgkin's Lymphoma (NHL). Treatments consisted of rituximab 375 mg/m2, i.v. on day 1; gemcitabine 1,000 mg/m2, i.v. on days 1 and 8, dexamethasone 40 mg i.v. on days 1-4, and cisplatin 25 mg/m2 i.v. on days 1-3, every 21 days. The primary end-points were the overall survival (OS) and progression-free survival (PFS). Secondary endpoints included response rate (ORR; CR) and toxicities. Eligible patients could then proceed to high-dose chemotherapy (HDC) and autologous stem cell transplantation (ASCT) or receive up to six treatment cycles. From January 2005 to December 2010, 50 successive patients at Tianjin cancer hospital lymphoma department were enrolled in this study. All patients were recurrent or refractory aggressive B-cell NHL, including diffuse large B-cell lymphoma (n=30) and follicular lymphoma grade 3b (n=20). The median follow-up time was 42 months (range, 12-70). After two cycles, the overall response rate was 72.0%, with a CR/CRu rate of 56%. The 2-year OS and PFS of all patients were 70.0 and 48.0%, respectively. Grade III-IV neutropenia and thrombocytopenia occurred in 34 and 40% of patients, respectively. Twenty-one patients (42%) proceeded to ASCT. Higher International Prognostic Index and refractory disease were independently associated with worse survival and progression-free survival. R-GDP chemotherapy in patients with refractory or relapsed aggressive B-Cell NHL was effective as a salvage therapy and helpful for HDC/ASCT.
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PMID:Rituximab, gemcitabine, cisplatin, and dexamethasone in patients with refractory or relapsed aggressive B-cell lymphoma. 2247 61

High-dose chemotherapy supported by autologous stem cell support/transplantation (HDT/ASCT) has been a standard of care over the last two decades in patients with relapsed or refractory(R/R) diffuse large B-cell lymphoma (DLBCL), which is sensitive to salvage chemotherapy. HDT/ASCT for high-risk DLBCL in upfront setting remains controversial, so it is not recommended for clinical practice. Various promising salvage chemotherapy regimens have been reported in phase 2 studies; however, two large randomized phase 3 studies showed similar efficacy of R-ICE vs. R-DHAP and R-GDP vs. R-DHAP. Since the registry data shows feasibility and efficacy of HDT/ASCT in elderly R/R DLBCL patients, older age (> 65 years) itself is not a contraindication for HDT/ASCT. Rituximab maintenance failed to demonstrate a significant benefit compared with observation only after HDT/ASCT. While sensitive R/R DLBCL might be cured by HDT/ASCT even in third-line therapy, the prognosis of insensitive R/R DLBCL is extremely poor. Further study to establish treatment strategies for high-risk patients defined by prognostic factors or biomarkers, and insensitive patients is warranted.
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PMID:Autologous Hematopoietic Stem Cell Transplantation for Diffuse Large B-Cell Lymphoma. 2798 Feb 99


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