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Berlin Brandenburg


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  • Michaelis, Martin  (9)
  • Cinatl Jr., J.  (9)
  • Valproic Acid
Type of Medium
  • 1
    Language: English
    In: FEBS Letters, 03 April 2007, Vol.581(7), pp.1317-1322
    Description: Treatment of transformed cells from leukemia or solid tumors with histone deacetylase inhibitors (HDACi) was shown to increase their sensitivity to NK cell lysis. In this study, treatment of IL-2-activated NK cells with HDACi including suberoylanilide hydroxamic acid and valproic acid was studied. Both drugs at therapeutic concentrations inhibited NK cell cytotoxicity on human leukemic cells. This inhibition was associated with decreased expression and function of NK cell activating receptors NKp46 and NKp30 as well as impaired granule exocytosis. NFκB activation in IL-2-activated NK cells was inhibited by both HDACi. Pharmacologic inhibition of NFκB activity resulted in similar effects on NK cell activity like those observed for HDACi. These results demonstrate for the first time that HDACi prevent NK cytotoxicity by downregulation of NK cell activating receptors probably through the inhibition of NFκB activation.
    Keywords: Cytotoxicity ; Nk Cells ; Histone Deacetylase Inhibitors ; Nk Cell Activating and Inhibitory Receptors ; Nuclear Factor Kappa B ; Biology ; Chemistry ; Anatomy & Physiology
    ISSN: 0014-5793
    E-ISSN: 1873-3468
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  • 2
    In: Current Pharmaceutical Design, November 2007, Vol.13(33), pp.3378-3393
    Description: The short chain fatty acid valproic acid (VPA, 2-propylpetanoic acid) is approved for the treatment of epilepsia, bipolar disorders and migraine and clinically used for schizophrenia. In 1999, the first clinical anti-cancer trial using VPA was initiated. Currently, VPA is examined in numerous clinical trials for different leukaemias and solid tumour entities. In addition to clinical assessment, the experimental examination of VPA as anti-cancer drug is ongoing and many questions remain unanswered. Although other mechanisms may also contribute to VPA-induced anti-cancer effects, inhibition of histone deacetylases appears to play a central role. This review focuses on recent developments regarding the anti-cancer activity of VPA.
    Keywords: Hdac ; Differentiation ; Combination Therapy ; Clinical Studies ; Valproic Acid ; Angiogenesis
    ISSN: 1381-6128
    E-ISSN: 18734286
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  • 3
    Language: English
    In: Current medicinal chemistry, August 2002, Vol.9(15), pp.1417-33
    Description: The branched-chain fatty acid valproic acid (VPA) is the most commonly used antiepileptic drug for treating generalized epilepsy. Although originally considered to be of low toxicity, VPA has proved to possess considerable teratogenic potential when applied to the pregnant epileptic women. During the last few years, it has become evident that some of the mechanisms which account for the malformations produced by VPA are related to distinct anti-tumor properties of this compound. This intriguing discovery opens novel aspects for the treatment of tumor patients. In the present review, the biological, biochemical and pharmacological properties of VPA are discussed. Analyses of structure-activity relationships can provide the necessary insight into the molecular structures responsible for the anti-tumor effects.
    Keywords: Antineoplastic Agents -- Pharmacology ; Valproic Acid -- Analogs & Derivatives
    ISSN: 0929-8673
    E-ISSN: 1875533X
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  • 4
    Language: English
    In: International Journal of Oncology, December 2004, Vol.25(6), pp.1795-1799
    Description: Valproic acid (VPA) as a differentiation inducing anti-neoplastic substance is currently tested in solid tumour and leukaemia patients. Previously, we were able to show that the anti-cancer activity of VPA was synergistically increased by interferon-α (IFN-α) in Be(2)-C neuroblastoma (NB) cells. Now, we studied the effects of VPA in combination with IFN-α on two other NB cell lines. UKF-NB-2 and UKF-NB-3 cell growth was synergistically inhibited by VPA and IFN-α. Cell cycle investigations revealed massive accumulation of cells in G0/G1-phase after a combined treatment with VPA and IFN-α. The VPA-induced accumulation of acetylated histones in NB cell nuclei that indicates inhibition of histone deacetylases was not further enhanced by the combination treatment with IFN-α. Most strikingly, VPA plus IFN-α synergistically inhibited growth of UKF-NB-3 xenograft tumours in nude mice and induced complete cures in two out of six animals, while single treatment merely inhibited tumour growth. The results of this study together with our previous report strongly encourage the clinical evaluation of VPA and IFN-α for NB patients.
    Keywords: Enzyme Inhibitors -- Pharmacology ; Interferon-Alpha -- Pharmacology ; Neuroblastoma -- Pathology ; Valproic Acid -- Pharmacology;
    ISSN: 1019-6439
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  • 5
    In: Cardiovascular Research, 2008, Vol. 77(3), pp.544-550
    Description: AIMS: The endothelium represents a natural site of human cytomegalovirus (HCMV) infection involved in viral spreading and persistence. Moreover, HCMV infection of endothelial cells has been associated with different pathological conditions of the cardiovascular system. Here, the influence of the antiepileptic drug valproic acid (VPA) was investigated on HCMV replication in human umbilical vein endothelial cells alone or in combination with the antiviral drugs ganciclovir, cidofovir or foscarnet.METHODS AND RESULTS: HCMV replication was observed by immunostaining for viral antigens and by virus yield assay. Protein expression and phosphorylation were examined by western blot. Cell viability was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide dye reduction assay. Therapeutic VPA concentrations (〈 or =1 mM) increased HCMV immediate early antigen, late antigen, and viral titres of different endotheliotropic and non-endotheliotropic HCMV strains in a concentration- and time-dependent manner up to 30-fold. Moreover, VPA impaired the antiviral activity of the anti-HCMV drugs ganciclovir, cidofovir, and foscarnet. VPA inhibits histone deacetylases (HDAC) and induces HDAC-independently extracellular signal-regulated kinases 1/2 (ERK 1/2) phosphorylation in endothelial cells. Both effects observed, HCMV stimulation and interference with antiviral drugs, depend on HDAC inhibition but not on ERK 1/2 phosphorylation.CONCLUSION: These findings suggest to carefully monitor the frequency of HCMV reactivation in cardiovascular patients treated with VPA (or other HDAC inhibitors) in comparison to control individuals.
    Keywords: Human Cytomegalovirus ; Antiviral Therapy ; Endothelium
    ISSN: 0008-6363
    E-ISSN: 1755-3245
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  • 6
    Language: English
    In: Medicinal Research Reviews, July 2005, Vol.25(4), pp.383-397
    Description: The short chain fatty acid valproic acid (VPA) and VPA‐analogs modulate the biology of diverse tumor cell entities by inducing differentiation, inhibiting proliferation, increasing apoptosis, and immunogenicity and by decreasing metastatic and angiogenetic potential. This review updates an earlier one in 2002, reflecting the interest in VPA as a potent anticancer drug. A number of studies show that the types of known tumor cells susceptible to VPA is steadily increasing. Of special note is the strong antineoplastic activity of VPA in chemoresistant cancer cells. A novel and promising approach is combining VPA with other drugs to achieve a broad therapeutic index. Clinical studies are underway and the preliminary results indicate that VPA alone or in combination offers a promising avenue of treatment, both in solid and hematopoetic malignancies. © 2005 Wiley Periodicals, Inc.
    Keywords: Valproic Acid ; Hdac ; Differentiation ; Angiogenesis ; Combination Therapy ; Clinical Studies
    ISSN: 0198-6325
    E-ISSN: 1098-1128
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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: Molecular pharmacology, March 2004, Vol.65(3), pp.520-7
    Description: Valproic acid (VPA) is a widely used antiepileptic agent that is undergoing clinical evaluation for anticancer therapy. We assessed the effects of VPA on angiogenesis in vitro and in vivo. In human umbilical vein endothelial cells, therapeutically relevant concentrations of VPA (0.25 to 1 mM) inhibited proliferation, migration, and tube formation. VPA 1 mM inhibited endothelial cell proliferation by 51 +/- 5%, migration by 86 +/- 11%, and tube formation by 82 +/- 3%. These changes were preceded by the hyperacetylation of histone H4, indicating the inhibition of histone deacetylase (HDAC), and a decreased expression of the endothelial nitric-oxide synthase (eNOS). The inhibition of endothelial cell tube formation by VPA was prevented by addition of the nitric oxide donor (Z)-1-[2-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA NONOate). The anticonvulsive active VPA derivative 2-ethyl-4-methylpentanoic acid, which does not inhibit HDAC, did not affect endothelial cell proliferation, tube formation, or eNOS expression. VPA was also found to inhibit angiogenesis in vivo in the chicken chorioallantoic membrane assay and in a Matrigel plug assay in mice. Embryos from VPA-treated mice showed disturbed vessel formation. These results indicate that therapeutic plasma levels of VPA inhibit angiogenesis by a mechanism involving a decrease in eNOS expression preceded by HDAC inhibition.
    Keywords: Angiogenesis Inhibitors -- Pharmacology ; Endothelium, Vascular -- Drug Effects ; Neovascularization, Physiologic -- Drug Effects ; Valproic Acid -- Pharmacology
    ISSN: 0026-895X
    E-ISSN: 15210111
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  • 9
    Language: English
    In: Investigative ophthalmology & visual science, September 2005, Vol.46(9), pp.3451-7
    Description: Human cytomegalovirus (HCMV) replication depends on different cellular pathways, including histone acetylation and extracellular-signal regulated kinases 1 and 2 (Erk 1/2). In the present study, the influence of therapeutic valproic acid (VPA) concentrations was investigated on HCMV replication in retinal pigment epithelial (RPE) cells. HCMV antigen expression and replication were detected by immunostaining, real-time RT-PCR, and determination of virus titers. Histone acetylation and Erk 1/2 phosphorylation were detected by Western blot. Pretreatment with VPA 〈 or =1 mM enhanced HCMV antigen expression and replication by up to ninefold. In addition to histone deacetylase (HDAC) inhibition, VPA stimulated Erk 1/2 phosphorylation in RPE cells. Investigation of six VPA derivatives revealed that S-2-pentyl-4-pentynoic acid was the only derivative that induced histone hyperacetylation, indicating HDAC inhibition, in the observed concentrations 〈 or =1 mM and that increased HCMV antigen expression. Other derivatives did not enhance HCMV replication in the tested concentrations, although some were found to induce Erk 1/2 phosphorylation. The mitogen-activated protein kinase kinase (MEK) inhibitor PD98059 inhibited VPA-induced Erk 1/2 phosphorylation but did not affect VPA-induced increased HCMV replication. In addition, the structurally nonrelated HDACI trichostatin A enhanced HCMV replication but did not affect Erk 1/2 phosphorylation in RPE cells. The data demonstrate that VPA stimulates HCMV replication by HDAC inhibition independent of Erk 1/2 phosphorylation in therapeutic concentrations in RPE cells. Therefore, patients at risk of HCMV retinitis who are treated with VPA or other HDAC inhibitors should be carefully monitored.
    Keywords: Histone Deacetylase Inhibitors ; Cytomegalovirus -- Physiology ; Enzyme Inhibitors -- Pharmacology ; Pigment Epithelium of Eye -- Virology ; Valproic Acid -- Pharmacology ; Virus Replication -- Drug Effects
    ISSN: 0146-0404
    E-ISSN: 15525783
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