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Berlin Brandenburg

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  • 1
    Language: English
    In: Biochemical Pharmacology, 2011, Vol.81(2), pp.251-258
    Description: Enzastaurin is a selective protein kinase Cβ inhibitor which is shown to have direct antitumor effect as well as suppress glycogen synthase kinase-3β (GSK-3β) phosphorylation (resulting in its activation) in both tumor tissues and peripheral blood mononuclear cells (PBMC). It is currently used in phase II trials for the treatment of colon cancer, refractory glioblastoma and diffuse large B cell lymphoma. In this study, the direct effect of enzastaurin on effector function of human natural killer (NK) cells was investigated. The results obtained showed that enzastaurin suppressed both natural and antibody-dependent cellular cytotoxicity (ADCC) of NK cells against different tumor targets. This inhibition was associated with a specific down-regulation of surface expression of NK cell activating receptor NKG2D and CD16 involved in natural cytotoxicity and ADCC respectively, as well as the inhibition of perforin release. Analysis of signal transduction revealed that enzastaurin activated GSK-3β by inhibition of GSK-3β phosphorylation. Treatment of NK cells with GSK-3β-specific inhibitor TDZD-8 prevented enzastaurin-induced inhibition of NK cell cytotoxicity. Apart from the known antitumor and antiangiogenic effects, these results demonstrate that enzastaurin suppresses NK cell activity and may therefore interfere with NK cell-mediated tumor control in enzastaurin-treated cancer patients.
    Keywords: Antibody-Dependent Cellular Cytotoxicity ; Natural Cytotoxicity ; Nkg2d ; Protein Kinase Cβ ; Glycogen Synthase Kinase-3β ; Pharmacy, Therapeutics, & Pharmacology ; Chemistry
    ISSN: 0006-2952
    E-ISSN: 1873-2968
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  • 2
    Language: English
    In: Biochemical Pharmacology, 15 January 2010, Vol.79(2), pp.188-197
    Description: Ribavirin, a broad-spectrum anti-viral drug, exhibits immunomodulatory activities. To study direct effects of ribavirin on natural killer (NK) cell effector functions and signaling, resting NK cells and interleukin (IL)-15-activated NK cells were treated for 5 days with therapeutic ribavirin concentrations ranging from 5 μg/ml to 20 μg/ml. Both resting and IL-15-activated NK cells that were not treated with ribavirin were used as control. Cytotoxicity assays, flow cytometry, enzyme linked immunosorbent assays, and Western blot experiments were performed to elucidate ribavirin effect on NK cells. Results showed that ribavirin (not toxic at concentrations tested; IC 〉 80 μg/ml) had no influence on lysis of target cells by freshly isolated NK cells. Conversely, ribavirin dose-dependently inhibited lysis of target cells by up to 66% and impaired interferon gamma production when IL-15-activated NK cells were used. IL-15-induced increased expression and hence function of NK cell activating receptors including NKp30, NKp44, NKp46 and NKG2D were selectively down-regulated and impaired. These inhibitory effects were associated with the down-regulation of IL-15 receptor beta and gamma expression. Accordingly, downstream events involved in NK cell signaling via IL-15 receptors including the activation of Janus kinase (Jak)-1, signal transducer and activator of transcription STAT-1, STAT-3, and STAT-5 as well as pathways responsible for NK cell degranulation including extracellular signal-regulated kinase (ERK1/2) and c-Jun N-terminal kinase (JNK) were impaired. These results reveal a novel mechanism by which ribavirin exerts its immunomodulatory activities.
    Keywords: Nk Cell Activating Receptors ; Nk Cell Signaling ; Nk Cell Degranulation ; Perforin and Granzyme B Release ; Il-15 Receptors ; Pharmacy, Therapeutics, & Pharmacology ; Chemistry
    ISSN: 0006-2952
    E-ISSN: 1873-2968
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  • 3
    Language: English
    In: Biochemical Pharmacology, 01 February 2010, Vol.79(3), pp.413-420
    Description: The antioxidant N-acetyl- -cysteine (NAC) had been shown to inhibit replication of seasonal human influenza A viruses. Here, the effects of NAC on virus replication, virus-induced pro-inflammatory responses and virus-induced apoptosis were investigated in H5N1-infected lung epithelial (A549) cells. NAC at concentrations ranging from 5 to 15 mM reduced H5N1-induced cytopathogenic effects (CPEs), virus-induced apoptosis and infectious viral yields 24 h post-infection. NAC also decreased the production of pro-inflammatory molecules (CXCL8, CXCL10, CCL5 and interleukin-6 (IL-6)) in H5N1-infected A549 cells and reduced monocyte migration towards supernatants of H5N1-infected A549 cells. The antiviral and anti-inflammatory mechanisms of NAC included inhibition of activation of oxidant sensitive pathways including transcription factor NF-κB and mitogen activated protein kinase p38. Pharmacological inhibitors of NF-κB (BAY 11-7085) or p38 (SB203580) exerted similar effects like those determined for NAC in H5N1-infected cells. The combination of BAY 11-7085 and SB203580 resulted in increased inhibitory effects on virus replication and production of pro-inflammatory molecules relative to either single treatment. NAC inhibits H5N1 replication and H5N1-induced production of pro-inflammatory molecules. Therefore, antioxidants like NAC represent a potential additional treatment option that could be considered in the case of an influenza A virus pandemic.
    Keywords: Ros ; NAC ; Cytokines ; H5n1 ; Apoptosis ; Pharmacy, Therapeutics, & Pharmacology ; Chemistry
    ISSN: 0006-2952
    E-ISSN: 1873-2968
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  • 4
    Language: English
    In: Biochemical Pharmacology, 2012, Vol.83(2), pp.228-240
    Description: 5-Lipoxygenase (5-LO) is a crucial enzyme of the arachidonic acid (AA) cascade and catalyzes the formation of bioactive leukotrienes (LTs) which are involved in inflammatory diseases and allergic reactions. The pathophysiological effects of LTs are considered to be prevented by 5-LO inhibitors. In this study we present cyclohexyl-[6-methyl-2-(4-morpholin-4-yl-phenyl)-imidazo[1,2- ]pyridin-3-yl]-amine ( ), a novel imidazo[1,2- ]pyridine based compound and its characterization in several assays. suppresses 5-LO activity in intact polymorphonuclear leukocytes with an IC value of 0.16 μM and exhibits full inhibitory potency in cell free assays (IC value of 0.05 μM for purified 5-LO). The efficacy of was not affected by the redox tone or the concentration of exogenous AA, characteristic drawbacks known for the class of nonredox-type 5-LO inhibitors. Furthermore, suppressed 5-LO activity independently of the cell stimulus or the activation pathway of 5-LO contrary to what is known for some nonredox-type inhibitors. Using molecular modeling and site-directed mutagenesis studies, we were able to derive a feasible binding region within the C2-like domain of 5-LO that can serve as a new starting point for optimization and development of new 5-LO inhibitors targeting this site. has promising effects on cell viability of tumor cells without mutagenic activity. Hence the drug may possess potential for intervention with inflammatory and allergic diseases and certain types of cancer including leukemia.
    Keywords: 5-Lipoxygenase ; Inflammation ; Inhibitor ; Leukotrienes ; Molecular Modeling ; Pharmacy, Therapeutics, & Pharmacology ; Chemistry
    ISSN: 0006-2952
    E-ISSN: 1873-2968
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  • 5
    Language: English
    In: Biochemical Pharmacology, 15 January 2010, Vol.79(2), pp.130-136
    Description: Artemisinin derivatives are well-tolerated anti-malaria drugs that also exert anti-cancer activity. Here, we investigated artemisinin and its derivatives dihydroartemisinin and artesunate in a panel of chemosensitive and chemoresistant human neuroblastoma cells as well as in primary neuroblastoma cultures. Only dihydroartemisinin and artesunate affected neuroblastoma cell viability with artesunate being more active. Artesunate-induced apoptosis and reactive oxygen species in neuroblastoma cells. Of 16 cell lines and two primary cultures, only UKF-NB-3 CDDP showed low sensitivity to artesunate. Characteristic gene expression signatures based on a previous analysis of artesunate resistance in the NCI60 cell line panel clearly separated UKF-NB-3 CDDP from the other cell lines. -Buthionine-S,R-sulfoximine, an inhibitor of GCL (glutamate–cysteine ligase), resensitised in part UKF-NB-3 CDDP cells to artesunate. This finding together with bioinformatic analysis of expression of genes involved in glutathione metabolism showed that this pathway is involved in artesunate resistance. These data indicate that neuroblastoma represents an artesunate-sensitive cancer entity and that artesunate is also effective in chemoresistant neuroblastoma cells.
    Keywords: Neuroblastoma ; Artesunate ; Artemisinin ; Chemoresistance ; Cancer ; Chemotherapy ; Pharmacy, Therapeutics, & Pharmacology ; Chemistry
    ISSN: 0006-2952
    E-ISSN: 1873-2968
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  • 6
    Language: English
    In: Biochemical Pharmacology, 13 November 2009, Vol.79(2), p.130
    Description: Artemisinin derivatives are well-tolerated anti-malaria drugs that also exert anti-cancer activity. Here, we investigated artemisinin and its derivatives dihydroartemisinin and artesunate in a panel of chemosensitive and chemoresistant human neuroblastoma cells as well as in primary neuroblastoma cultures. Only dihydroartemisinin and artesunate affected neuroblastoma cell viability with artesunate being more active. Artesunate induced apoptosis and reactive oxygen species in neuroblastoma cells. Of 16 cell lines and two primary cultures, only UKF-NB-3CDDP showed low sensitivity to artesunate. Characteristic gene expression signatures based on a previous analysis of artesunate resistance in the NCI60 cell line panel clearly separated UKF-NB-3CDDP from the other cell lines. L-Buthionine-S,R-sulfoximine, an inhibitor of GCL (glutamate-cysteine ligase), resensitised in part UKF-NB-3CDDP cells to artesunate. This finding together with bioinformatic analysis of expression of genes involved in glutathione metabolism showed that this pathway is involved in artesunate resistance. These data indicate that neuroblastoma represents an artesunate-sensitive cancer entity and that artesunate is also effective in chemoresistant neuroblastoma cells.
    Keywords: Neuroblastoma ; Artesunate ; Artemisinin ; Chemoresistance ; Cancer ; Chemotherapy ; Pharmacy, Therapeutics, & Pharmacology ; Chemistry
    ISSN: 0006-2952
    E-ISSN: 1873-2968
    Source: Hyper Article en Ligne (CCSd)
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  • 7
    Language: English
    In: Biochemical Pharmacology, 2004, Vol.68(3), pp.531-538
    Description: Valproic acid (2-propylpentanoic acid, VPA), an effective inhibitor of histone deacetylases (HDAC) is used for the treatment of epilepsia. In this study, structure–activity relationships for the action of structurally modified VPA derivatives on human cytomegalovirus (HCMV) replication and HDAC inhibition were defined. Pretreatment of human foreskin fibroblasts with VPA (0.125–1 mM) caused a concentration-dependent increase of HCMV immediate early and antigen late antigen expression. Structure–activity relationships of VPA derivatives for HCMV stimulation were compared to those for teratogenic action and those for HDAC inhibition. Side chain elongation and introduction of a triple bond in 4-position of the other chain caused teratogenicity, stimulated HCMV replication, and increased HDAC inhibition, as demonstrated by enhanced levels of acetylated histones. Teratogenic VPA derivatives with a branched chain in 3-position as well as a non-teratogenic anticonvulsive active VPA derivative did not stimulate HCMV or accumulation of acetylated histones. This demonstrates a strict correlation between inhibition of HDAC and increased HCMV replication.
    Keywords: Valproic Acid ; Human Cytomegalovirus ; Histone Deacetylases ; Teratogenicity ; Structure–Activity Relationship ; Pharmacy, Therapeutics, & Pharmacology ; Chemistry
    ISSN: 0006-2952
    E-ISSN: 1873-2968
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  • 8
    Language: English
    In: Biochemical pharmacology, 15 July 2002, Vol.64(2), pp.239-46
    Description: Continuous cultivation of T-lymphoid H9 cells in the presence of 3'-azido-2',3'-dideoxythymidine (AZT) resulted in a cell variant cross-resistant to both thymidine and deoxycytidine analogs. Cytotoxic effects of AZT, 2',3'-didehydro-3'-deoxythymidine as well as different deoxycytidine analogs such as 2',3'-dideoxycytidine, 2',2'-difluoro-2'-deoxycytidine (dFdC) and 1-ss-D-arabinofuranosylcytosine (Ara-C) were strongly reduced in H9 cells continuously exposed to AZT when compared to parental cells (〉8.3-, 〉6.6-, 〉9.1-, 5 x 10(4)-, 5 x 10(3)-fold, respectively). Moreover, anti-HIV-1 effects of AZT, d4T, ddC and 2',3'-dideoxy-3'-thiacytidine (3TC) were significantly diminished (〉222-, 〉25-, 〉400-, 〉200-fold, respectively) in AZT-resistant H9 cells. Study of cellular mechanisms responsible for cross-resistance to pyrimidine analogs in AZT-resistant H9 cells revealed decreased mRNA levels of thymidine kinase 1 (TK1) and lack of deoxycytidine kinase (dCK) mRNA expression. The loss of dCK gene expression was confirmed by western blot analysis of dCK protein as well as dCK enzyme activity assay. Moreover, enzyme activity of TK1 and TK2 was reduced in AZT-resistant cells. In order to determine whether lack of dCK affected the formation of the active triphosphate of the deoxycytidine analog dFdC, dFdCTP accumulation and retention was measured in H9 parental and AZT-resistant cells after exposure to 1 and 10 microM dFdC. Parental H9 cells accumulated about 30 and 100 pmol dFdCTP/10(6) cells after 4hr, whereas in AZT-resistant cells no dFdCTP accumulation was detected. These results demonstrate that continuous treatment of H9 cells in the presence of AZT selected for a thymidine analog resistant cell variant with cross-resistance to deoxycytidine analogs, due to deficiency in TK1, TK2, and dCK.
    Keywords: Anti-HIV Agents -- Pharmacology ; Deoxycytidine -- Analogs & Derivatives ; Deoxycytidine Kinase -- Metabolism ; T-Lymphocytes -- Drug Effects ; Thymidine Kinase -- Metabolism ; Zidovudine -- Pharmacology
    ISSN: 0006-2952
    Source: MEDLINE/PubMed (U.S. National Library of Medicine)
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  • 9
    Language: English
    In: Biochemical Pharmacology, 2002, Vol.64(2), pp.239-246
    Description: Continuous cultivation of T-lymphoid H9 cells in the presence of 3′-azido-2′,3′-dideoxythymidine (AZT) resulted in a cell variant cross-resistant to both thymidine and deoxycytidine analogs. Cytotoxic effects of AZT, 2′,3′-didehydro-3′-deoxythymidine as well as different deoxycytidine analogs such as 2′,3′-dideoxycytidine, 2′,2′-difluoro-2′-deoxycytidine (dFdC) and 1-ß-D-arabinofuranosylcytosine (Ara-C) were strongly reduced in H9 cells continuously exposed to AZT when compared to parental cells (〉8.3-, 〉6.6-, 〉9.1-, 5×10 4 -, 5×10 3 -fold, respectively). Moreover, anti-HIV-1 effects of AZT, d4T, ddC and 2′,3′-dideoxy-3′-thiacytidine (3TC) were significantly diminished (〉222-, 〉25-, 〉400-, 〉200-fold, respectively) in AZT-resistant H9 cells. Study of cellular mechanisms responsible for cross-resistance to pyrimidine analogs in AZT-resistant H9 cells revealed decreased mRNA levels of thymidine kinase 1 (TK1) and lack of deoxycytidine kinase (dCK) mRNA expression. The loss of dCK gene expression was confirmed by western blot analysis of dCK protein as well as dCK enzyme activity assay. Moreover, enzyme activity of TK1 and TK2 was reduced in AZT-resistant cells. In order to determine whether lack of dCK affected the formation of the active triphosphate of the deoxycytidine analog dFdC, dFdCTP accumulation and retention was measured in H9 parental and AZT-resistant cells after exposure to 1 and 10 μM dFdC. Parental H9 cells accumulated about 30 and 100 pmol dFdCTP/10 6 cells after 4 hr, whereas in AZT-resistant cells no dFdCTP accumulation was detected. These results demonstrate that continuous treatment of H9 cells in the presence of AZT selected for a thymidine analog resistant cell variant with cross-resistance to deoxycytidine analogs, due to deficiency in TK1, TK2, and dCK.
    Keywords: Cellular Resistance ; Zidovudine ; Gemcitabine ; Cytarabine ; Thymidine Kinase 1 ; Deoxycytidine Kinase ; Pharmacy, Therapeutics, & Pharmacology ; Chemistry
    ISSN: 0006-2952
    E-ISSN: 1873-2968
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