Refine
Year of publication
Document Type
- Article (31)
- Contribution to a Periodical (3)
- Conference Proceeding (1)
Keywords
- 5-lipoxygenase (4)
- inflammation (4)
- polypharmacology (3)
- Dicer (2)
- soluble epoxide hydrolase (2)
- 1α,25(OH)2D3 (1)
- 5-Lipoxygenase (1)
- 5-lipoxygenase; (1)
- AF4 (1)
- Compound Database (1)
Institute
- 5-Lipoxygenase: underappreciated role of a pro-inflammatory enzyme in tumorigenesis (2010)
- Leukotrienes constitute a group of bioactive lipids generated by the 5-lipoxygenase (5-LO) pathway. An increasing body of evidence supports an acute role for 5-LO products already during the earliest stages of pancreatic, prostate, and colorectal carcinogenesis. Several pieces of experimental data form the basis for this hypothesis and suggest a correlation between 5-LO expression and tumor cell viability. First, several independent studies documented an overexpression of 5-LO in primary tumor cells as well as in established cancer cell lines. Second, addition of 5-LO products to cultured tumor cells also led to increased cell proliferation and activation of anti-apoptotic signaling pathways. 5-LO antisense technology approaches demonstrated impaired tumor cell growth due to reduction of 5-LO expression. Lastly, pharmacological inhibition of 5-LO potently suppressed tumor cell growth by inducing cell cycle arrest and triggering cell death via the intrinsic apoptotic pathway. However, the documented strong cytotoxic off-target effects of 5-LO inhibitors, in combination with the relatively high concentrations of 5-LO products needed to achieve mitogenic effects in cell culture assays, raise concern over the assignment of the cause, and question the relationship between 5-LO products and tumorigenesis. Keywords: leukotriene, apoptosis, cell proliferation, mitogenic effects, cytotoxicity
- Identification and characterization of a new protein isoform of human 5-lipoxygenase (2016)
- Leukotrienes (LTs) are inflammatory mediators that play a pivotal role in many diseases like asthma bronchiale, atherosclerosis and in various types of cancer. The key enzyme for generation of LTs is the 5-lipoxygenase (5-LO). Here, we present a novel putative protein isoform of human 5-LO that lacks exon 4, termed 5-LOΔ4, identified in cells of lymphoid origin, namely the Burkitt lymphoma cell lines Raji and BL41 as well as primary B and T cells. Deletion of exon 4 does not shift the reading frame and therefore the mRNA is not subjected to non-mediated mRNA decay (NMD). By eliminating exon 4, the amino acids Trp144 until Ala184 are omitted in the corresponding protein. Transfection of HEK293T cells with a 5-LOΔ4 expression plasmid led to expression of the corresponding protein which suggests that the 5-LOΔ4 isoform is a stable protein in eukaryotic cells. We were also able to obtain soluble protein after expression in E. coli and purification. The isoform itself lacks canonical enzymatic activity as it misses the non-heme iron but it still retains ATP-binding affinity. Differential scanning fluorimetric analysis shows two transitions, corresponding to the two domains of 5-LO. Whilst the catalytic domain of 5-LO WT is destabilized by calcium, addition of calcium has no influence on the catalytic domain of 5-LOΔ4. Furthermore, we investigated the influence of 5-LOΔ4 on the activity of 5-LO WT and proved that it stimulates 5-LO product formation at low protein concentrations. Therefore regulation of 5-LO by its isoform 5-LOΔ4 might represent a novel mechanism of controlling the biosynthesis of lipid mediators.
- Trichostatin A induces 5-lipoxygenase promoter activity and mRNA expression via inhibition of histone deacetylase 2 and 3 (2012)
- The 5-lipoxygenase (5-LO) is the key enzyme in the formation of leukotrienes. We have previously shown that the histone deacetylase (HDAC) inhibitor trichostatin A (TSA) activates 5-LO transcription via recruitment of Sp1, Sp3 and RNA polymerase II to the proximal promoter. To identify the HDACs involved in the regulation of 5-LO promoter activity isoform-specific HDAC inhibitors were applied. 5-LO promoter activity and mRNA expression were up-regulated by the class I HDAC inhibitors apicidin and MS-275 but not by class II inhibitors. Knockdown of HDAC 1, 2 and 3 revealed that HDAC2 and HDAC3 but not HDAC1 is involved in the up-regulation of 5-LO mRNA expression. To analyse the chromatin modifications at the 5-LO promoter associated with HDAC inhibition, the time course of 5-LO mRNA induction by trichostatin A was investigated and the concomitant changes in histone modifications at the 5-LO promoter in HL-60, U937 and Mono Mac6 cells were determined. Chromatin immunoprecipitation analysis revealed that trichostatin A increases acetylation of histones H3 and H4 at the 5-LO core promoter in HL-60 and U937 cells whereas no significant changes were observed in Mono Mac6 cells. The appearance of H3 and H4 acetylation preceded the 5-LO mRNA induction whereas in all three cell lines, induction of 5-LO mRNA expression correlated with histone H3 lysine 4 trimethylation (H3K4me3), a marker for transcriptional activity of gene promoters.
- Novel insights into the regulation of cyclooxygenase-2 expression by platelet-cancer cell cross-talk (2015)
- Platelets are activated by the interaction with cancer cells and release enhanced levels of lipid mediators [such as thromboxane (TX)A2 and prostaglandin (PG)E2, generated from arachidonic acid (AA) by the activity of cyclooxygenase (COX)-1], granule content, including ADP and growth factors, chemokines, proteases and Wnt proteins. Moreover, activated platelets shed different vesicles, such as microparticles (MPs) and exosomes (rich in genetic material such as mRNAs and miRNAs). These platelet-derived products induce several phenotypic changes in cancer cells which confer high metastatic capacity. A central event involves an aberrant expression of COX-2 which influences cell-cycle progression and contribute to the acquisition of a cell migratory phenotype through the induction of epithelial mesenchymal transition genes and down-regulation of E-cadherin expression. The identification of novel molecular determinants involved in the cross-talk between platelets and cancer cells has led to identify novel targets for anti-cancer drug development.
- R-Flurbiprofen traps prostaglandins within cells by inhibition of multidrug resistance-associated protein-4 (2016)
- R-flurbiprofen is the non-COX-inhibiting enantiomer of flurbiprofen and is not converted to S-flurbiprofen in human cells. Nevertheless, it reduces extracellular prostaglandin E2 (PGE2) in cancer or immune cell cultures and human extracellular fluid. Here, we show that R-flurbiprofen acts through a dual mechanism: (i) it inhibits the translocation of cPLA2α to the plasma membrane and thereby curtails the availability of arachidonic acid and (ii) R-flurbiprofen traps PGE2 inside of the cells by inhibiting multidrug resistance–associated protein 4 (MRP4, ABCC4), which acts as an outward transporter for prostaglandins. Consequently, the effects of R-flurbiprofen were mimicked by RNAi-mediated knockdown of MRP4. Our data show a novel mechanism by which R-flurbiprofen reduces extracellular PGs at physiological concentrations, particularly in cancers with high levels of MRP4, but the mechanism may also contribute to its anti-inflammatory and immune-modulating properties and suggests that it reduces PGs in a site- and context-dependent manner.
- Wie ein Schlag aus heiterem Himmel – Wolfgang Niedecken und sein Umgang mit dem Schlaganfall (2013)
- Bei seiner Einschulung hatte Wolfgang Niedecken ein besonderes Erlebnis, als er im Alter von 6 Jahren bemerkte, dass es höchste Zeit war, ordentlich sprechen zu lernen. Im Elternhaus war ausschließlich Kölsch gesprochen worden. Hochdeutsch war seine erste Fremdsprache, die sie in letzter Konsequenz auch immer geblieben ist. Denken, empfinden und träumen tut Niedecken nach wie vor auf Kölsch, wie er selbst beteuert. Im Sommer 1976 schreibt Wolfgang Niedecken seinen ersten Song auf Kölsch: "Helfe kann dir keiner". 1979 erscheint sein erstes Album mit dem Titel: "Wolfgang Niedecken’s BAP rockt andere kölsche Leeder". Nie hat sich BAP auf seinen Tourneen vor den „Karren politischer Machthaber“ spannen lassen. Zu Zeiten zweier deutscher Staaten sorgten die offenen Worte von „Deshalv spill`mer he“ für einen Eklat. Das Lied sprach sich unmissverständlich nicht nur für die westdeutsche Friedensbewegung, sondern ebenfalls für die ostdeutschen Friedens- und Menschenrechtsinitiativen aus. Als die DDR-Kulturbehörden BAP verboten, den Song zu spielen, platzt am Vorabend des ersten Konzertes im Berliner Palast der Republik die über 14 Stationen geplante und längst ausverkaufte DDR-Tournee. Am 9. November 1992 findet das „Arsch huh“-Konzert gegen Ausländerfeindlichkeit und Rassismus auf dem Kölner Chlodwigplatz vor über 100.000 Menschen statt. Danach ähnliche Konzerte in Frankfurt „Heute die, morgen Du“ und in Leipzig „Gewalt ätzt“ vor ähnlich großer Kulisse. Für sein gesellschaftspolitisches Engagement bekommt Niedecken 1998 das Bundesverdienstkreuz von Bundespräsident Roman Herzog überreicht. In der Laudatio heißt es: „Kölsch-Rock, BAP und Kölner Dialekt sind untrennbar mit ihm verbunden. Er ist einer der profiliertesten Rockmusiker Deutschlands. Als engagierter Künstler hat er sich nachhaltig für Frieden, Toleranz, Demokratie und gegen Fremdenfeindlichkeit eingesetzt.“ Zu Niedeckens 60. Geburtstag, den er am 30. März 2011 mit etwa 500 Gästen auf einem Rheinschiff feiert, sendet der WDR die „Niedecken-Nacht“. Zu seinem Geburtstag erscheint im Verlag Hoffmann und Campe auch das Buch „Für 'ne Moment. Autobiographie“. Auf über 500 Seiten erzählt der Musiker von seiner Familie, einer behüteten frühen Kindheit und der schwierigen Zeit als Heranwachsender im katholischen Internat, von seinem Kunststudium und Aufenthalten in der New Yorker Kunstszene, der ehe zufälligen Gründung von BAP, die zur erfolgreichsten Mundartgruppe Deutschlands wurde. Und dann das: Am 2. November gegen 13 Uhr bemerkt Wolfgang Niedecken beim Lesen, „dass ich nichts mehr kapierte. Ich musste die Seiten immer wieder neu lesen. Dann wurde es nebelig vor den Augen, alles sah merkwürdig aus, mein ganzes Umfeld hatte amorphe Formen. Und dann begegnete ich Gott sei Dank meinem Schutzengel.“ Wolfgang Niedecken hatte einen Schlaganfall erlitten, obwohl er eigentlich kein typischer Schlaganfallpatient war. Es kann also jeden treffen! Dank des schnellen Reagierens seiner Frau Tina konnte das Schlimmste verhindert werden.
- Peroxisome Proliferator-Activated Receptor alpha (PPAR alpha) down-regulation in cystic fibrosis lymphocytes (2006)
- Background: PPARs exhibit anti-inflammatory capacities and are potential modulators of the inflammatory response. We hypothesized that their expression and/or function may be altered in cystic fibrosis (CF), a disorder characterized by an excessive host inflammatory response. Methods: PPARα, β and γ mRNA levels were measured in peripheral blood cells of CF patients and healthy subjects via RT-PCR. PPARα protein expression and subcellular localization was determined via western blot and immunofluorescence, respectively. The activity of PPARα was analyzed by gel shift assay. Results: In lymphocytes, the expression of PPARα mRNA, but not of PPARβ, was reduced (-37%; p < 0.002) in CF patients compared with healthy persons and was therefore further analyzed. A similar reduction of PPARα was observed at protein level (-26%; p < 0.05). The transcription factor was mainly expressed in the cytosol of lymphocytes, with low expression in the nucleus. Moreover, DNA binding activity of the transcription factor was 36% less in lymphocytes of patients (p < 0.01). For PPARα and PPARβ mRNA expression in monocytes and neutrophils, no significant differences were observed between CF patients and healthy persons. In all cells, PPARγ mRNA levels were below the detection limit. Conclusion: Lymphocytes are important regulators of the inflammatory response by releasing cytokines and antibodies. The diminished lymphocytic expression and activity of PPARα may therefore contribute to the inflammatory processes that are observed in CF.
- AF4 and AF4-MLL mediate transcriptional elongation of 5-lipoxygenase mRNA by 1, 25-dihydroxyvitamin D3 (2015)
- The human 5-lipoxygenase (5-LO), encoded by the ALOX5 gene, is the key enzyme in the formation of pro-inflammatory leukotrienes. ALOX5 gene transcription is strongly stimulated by calcitriol (1α, 25-dihydroxyvitamin D3) and TGFβ (transforming growth factor-β). Here, we investigated the influence of MLL (activator of transcript initiation), AF4 (activator of transcriptional elongation) as well as of the leukemogenic fusion proteins MLL-AF4 (ectopic activator of transcript initiation) and AF4-MLL (ectopic activator of transcriptional elongation) on calcitriol/TGFβ-dependent 5-LO transcript elongation. We present evidence that the AF4 complex directly interacts with the vitamin D receptor (VDR) and promotes calcitriol-dependent ALOX5 transcript elongation. Activation of transcript elongation was strongly enhanced by the AF4-MLL fusion protein but was sensitive to Flavopiridol. By contrast, MLL-AF4 displayed no effect on transcriptional elongation. Furthermore, HDAC class I inhibitors inhibited the ectopic effects caused by AF4-MLL on transcriptional elongation, suggesting that HDAC class I inhibitors are potential therapeutics for the treatment of t(4;11)(q21;q23) leukemia.
- How to effectively treat acute leukemia patients bearing MLL-rearrangements ? (2017)
- Chromosomal translocations - leading to the expression of fusion genes - are well-studied genetic abberrations associated with the development of leukemias. Most of them represent altered transcription factors that affect transcription or epigenetics, while others - like BCR-ABL - are enhancing signaling. BCR-ABL has become the prototype for rational drug design, and drugs like Imatinib and subsequently improved drugs have a great impact on cancer treatments. By contrast, MLL-translocations in acute leukemia patients are hard to treat, display a high relapse rate and the overall survival rate is still very poor. Therefore, new treatment modalities are urgently needed. Based on the molecular insights of the most frequent MLL rearrangements, BET-, DOT1L-, SET- and MEN1/LEDGF-inhibitors have been developed and first clinical studies were initiated. Not all results of these studies have are yet available, however, a first paper reports a failure in the DOT1L-inhibitor study although it was the most promising drug based on literature data. One possible explanation is that all of the above mentioned drugs also target the cognate wildtype proteins. Here, we want to strengthen the fact that efforts should be made to develop drugs or strategies to selectively inhibit only the fusion proteins. Some examples will be given that follow exactly this guideline, and proof-of-concept experiments have already demonstrated their feasibility and effectiveness. Some of the mentioned approaches were using drugs that are already on the market, indicating that there are existing opportunities for the future which should be implemented in future therapy strategies.
- Wie sekundäre Pflanzeninhaltsstoffe uns vor Krankheiten schützen : von molekularen Wirkmechanismen zu neuen Medikamenten (2006)
- Wirkungen von Heilpflanzen, Gewürzen, Tees und Lebensmitteln werden in der Naturheilkunde seit der Antike genutzt. Pharmakologisch wirksam sind in der Regel nur die sekundären Pflanzeninhaltsstoffe. Diese in den oft aus vielen Bestandteilen zusammengesetzten Naturstoffen aufzuspüren und ihren molekularbiologischen Wirkungsmechanismus im Körper aufzuklären, ist das Ziel eines Forschungsnetzwerks am Frankfurter ZAFES (Zentrum für Arzneimittelforschung, -Entwicklung und -Sicherheit). So konnten Pharmazeuten und Kliniker gemeinsam herausfinden, wie ein Bestandteil des Rotweins, das Resveratrol, vor Darmkrebs schützt. Die Inhaltsstoffe von Salbei und Rosmarin bieten vielversprechende Ausgangspunkte für neue Medikamente gegen Altersdiabetes. Weihrauch, Myrte und Johanniskraut enthalten Wirkstoffe, die Schlüsselenzyme für Entzündungsreaktionen – etwa bei rheumatischen Beschwerden – hemmen.
