title: Trichostatin A effectively induces apoptosis in chronic lymphocytic leukemia cells via inhibition of Wnt signaling and histone deacetylation.
abstract: BACKGROUND
  The ontogenetic Wnt pathway shows almost no activity in adult tissues. In contrast, chronic lymphocytic leukemia (CLL) cells show constitutionally active Wnt signaling, which is associated with upregulated levels of pathway members such as Wnt3 and lymphoid enhancer-binding factor-1. Functionally, this results in increased resistance to apoptosis. We therefore assumed that targeting members of the pathway could reveal new therapeutic options for the treatment of CLL.
  
  
  METHODS
  Screening a Wnt compound library with 75 Wnt modulators via ATP assay revealed Trichostatin A as an outstanding substance with strong viability decreasing effects on CLL cells and little effect on healthy peripheral blood mononuclear cells (PBMCs). Further survival analysis was performed via fluorescence-activated cell sorting analysis.
  
  
  RESULTS
  A maximum effect was achieved after 48 h with a wide therapeutic window in contrast to PBMCs (CLL cells: 0.253 µM, PBMCs: 145.22 µM). Trichostatin A induced caspases and acted via a dual mechanism to reveal histone and non-histone targets. Histone targets were displayed in deacetylation inhibition at DNA level, and non-histone targeting was demonstrated by elevated levels of Dickkopf-related protein 1 mRNA. Primary cells of patients with critical mutations such as TP53 or those who had already undergone extensive previous treatment responded well to the treatment. Moreover, the approved histone deacetylase (HDAC) inhibitor suberoylanilidehydroxamic acid (SAHA) was not as effective as Trichostatin A (Trichostatin A: 0.253 µM, SAHA: 7.88 µM). Combining Trichostatin A with established CLL drugs fludarabine or bendamustine showed an additive effect in vitro.
  
  
  CONCLUSIONS
  Taken together, Trichostatin A appears to act via a dual anti-HDAC/Wnt mechanism with a high selectivity and efficacy in CLL and therefore warrants further investigation.
authors.affiliation: Department I of Internal Medicine, University at Cologne, Kerpener Strasse 62, 50937, Cologne, Germany.
authors.forename: Lukas
authors.initials: L
authors.lastname: Peiffer
authors.forename: Simon Jonas
authors.initials: SJ
authors.lastname: Poll-Wolbeck
authors.forename: Hanna
authors.initials: H
authors.lastname: Flamme
authors.forename: Iris
authors.initials: I
authors.lastname: Gehrke
authors.forename: Michael
authors.initials: M
authors.lastname: Hallek
authors.forename: Karl-Anton
authors.initials: KA
authors.lastname: Kreuzer
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D004357:Drug Synergism; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006657:Histones / Q000378:metabolism*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D007963:Leukocytes, Mononuclear / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D017384:Sequence Deletion; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics; D000077337:Vorinostat; D060449:Wnt Signaling Pathway / Q000187:drug effects*
chemical_list: D000970:Antineoplastic Agents; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D006877:Hydroxamic Acids; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C012589:trichostatin A; D000077337:Vorinostat; C505407:CASP3 protein, human; C505520:CASP7 protein, human; D053148:Caspase 3; D053179:Caspase 7