title: Autophagy-related cell death by pan-histone deacetylase inhibition in liver cancer.
abstract: Autophagy is a homeostatic, catabolic degradation process and cell fate essential regulatory mechanism. Protracted autophagy triggers cell death; its aberrant function is responsible for several malignancies. Panobinostat, a potent pan-deacetylase inhibitor, causes endoplasmic reticulum stress-induced cell death. The aim of this study was to investigate the role of autophagy in deacetylase inhibitor-triggered liver cancer cell death.HepG2 (p53wt) and Hep3B (p53 null) liver cancer cell lines were exposed to panobinostat. RT-qPCR and western blot confirmed autophagic factor modulation. Immuno-fluorescence, -precipitation and -histochemistry as well as transmission electron microscopy verified autophagosome formation. The cytotoxicity of panobinostat and autophagy modulators was detected using a real time cell viability assay.Panobinostat induced autophagy-related factor expression and aggregation. Map1LC3B and Beclin1 were significantly over-expressed in HepG2 xenografts in nude mice treated with panobinostat for 4 weeks. Subcellular distribution of Beclin1 increased with the appearance of autophagosomes-like aggregates. Cytosolic loss of p53, in HepG2, and p73, in Hep3B cells, and a corresponding gain of their nuclear level, together with modulation of DRAM1, were observed. Autophagosome aggregation was visible after 6 h of treatment. Treatment of cells stably expressing GFP-RFPtag Map1LC3B resulted in aggregation and a fluorescence switch, thus confirming autophagosome formation and maturation. Tamoxifen, an inducer of autophagy, caused only a block in cell proliferation; but in combination with panobinostat it resulted in cell death.Autophagy triggers cell demise in liver cancer. Its modulation by the combination of tamoxifen and panobinostat could be a new option for palliative treatment of hepatocellular carcinoma.
authors.affiliation: Department of Visceral, Thoracic and Vascular Surgery, Philipps University of Marburg, Marburg, Germany.
authors.forename: Pietro
authors.initials: P
authors.lastname: Di Fazio
authors.affiliation: Institute for Biomedical Aging Research, University of Innsbruck, Rennweg, Innsbruck, Austria.
authors.forename: Petra
authors.initials: P
authors.lastname: Waldegger
authors.affiliation: Institute for Anatomy I, University of Erlangen-Nurnberg, Erlangen, Germany.
authors.forename: Samir
authors.initials: S
authors.lastname: Jabari
authors.affiliation: Department of Urology, Philipps University of Marburg, Marburg, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Lingelbach
authors.affiliation: Department of Visceral, Thoracic and Vascular Surgery, Philipps University of Marburg, Marburg, Germany.
authors.forename: Roberta
authors.initials: R
authors.lastname: Montalbano
authors.affiliation: Institute for Surgical Research, Philipps University of Marburg, Marburg, Germany.|Experimental Medicine Oncology, Bayer Pharma AG, Berlin Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Ocker
authors.affiliation: Department of Visceral, Thoracic and Vascular Surgery, Philipps University of Marburg, Marburg, Germany.
authors.forename: Emily P
authors.initials: EP
authors.lastname: Slater
authors.affiliation: Department of Visceral, Thoracic and Vascular Surgery, Philipps University of Marburg, Marburg, Germany.
authors.forename: Detlef K
authors.initials: DK
authors.lastname: Bartsch
authors.affiliation: Institute of Pathology, Paracelsus Medical University/Salzburger Landeskliniken (SALK), Salzburg, Austria.
authors.forename: Romana
authors.initials: R
authors.lastname: Illig
authors.affiliation: Institute of Pathology, Paracelsus Medical University/Salzburger Landeskliniken (SALK), Salzburg, Austria.
authors.forename: Daniel
authors.initials: D
authors.lastname: Neureiter
authors.affiliation: Department of Gastroenterology and Endocrinology, Philipps University of Marburg, Marburg, Germany.
authors.forename: Thaddeus T
authors.initials: TT
authors.lastname: Wissniowski
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D001343:Autophagy / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D016923:Cell Death / Q000187:drug effects; D056945:Hep G2 Cells; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology*; D008113:Liver Neoplasms / Q000473:pathology*; D051379:Mice; D008819:Mice, Nude; D000077767:Panobinostat; D013629:Tamoxifen / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays
chemical_list: D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D007211:Indoles; D013629:Tamoxifen; D000077767:Panobinostat
keywords: autophagic cell death; autophagosomes; cancer therapy; liver cancer; pan-deacetylase inhibitor