title: Hepatocellular toxicity of benzbromarone: effects on mitochondrial function and structure.
abstract: Benzbromarone is an uricosuric structurally related to amiodarone and a known mitochondrial toxicant. The aim of the current study was to improve our understanding in the molecular mechanisms of benzbromarone-associated hepatic mitochondrial toxicity. In HepG2 cells and primary human hepatocytes, ATP levels started to decrease in the presence of 25-50μM benzbromarone for 24-48h, whereas cytotoxicity was observed only at 100μM. In HepG2 cells, benzbromarone decreased the mitochondrial membrane potential starting at 50μM following incubation for 24h. Additionally, in HepG2 cells, 50μM benzbromarone for 24h induced mitochondrial uncoupling,and decreased mitochondrial ATP turnover and maximal respiration. This was accompanied by an increased lactate concentration in the cell culture supernatant, reflecting increased glycolysis as a compensatory mechanism to maintain cellular ATP. Investigation of the electron transport chain revealed a decreased activity of all relevant enzyme complexes. Furthermore, treatment with benzbromarone was associated with increased cellular ROS production, which could be located specifically to mitochondria. In HepG2 cells and in isolated mouse liver mitochondria, benzbromarone also reduced palmitic acid metabolism due to an inhibition of the long-chain acyl CoA synthetase. In HepG2 cells, benzbromarone disrupted the mitochondrial network, leading to mitochondrial fragmentation and a decreased mitochondrial volume per cell. Cell death occurred by both apoptosis and necrosis. The study demonstrates that benzbromarone not only affects the function of mitochondria in HepG2 cells and human hepatocytes, but is also associated with profound changes in mitochondrial structure which may be associated with apoptosis.
authors.affiliation: Clinical Pharmacology & Toxicology, University Hospital Basel, Switzerland; Department of Biomedicine, University of Basel, Switzerland.
authors.forename: Andrea
authors.initials: A
authors.lastname: Felser
authors.affiliation: Clinical Pharmacology & Toxicology, University Hospital Basel, Switzerland; Department of Biomedicine, University of Basel, Switzerland; Swiss Center of Applied Human Toxicology (SCAHT), Switzerland.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Lindinger
authors.affiliation: Clinical Pharmacology & Toxicology, University Hospital Basel, Switzerland; Department of Biomedicine, University of Basel, Switzerland.
authors.forename: Dominik
authors.initials: D
authors.lastname: Schnell
authors.affiliation: Swiss Center of Applied Human Toxicology (SCAHT), Switzerland; Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, Switzerland.
authors.forename: Denise V
authors.initials: DV
authors.lastname: Kratschmar
authors.affiliation: Swiss Center of Applied Human Toxicology (SCAHT), Switzerland; Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, Switzerland.
authors.forename: Alex
authors.initials: A
authors.lastname: Odermatt
authors.affiliation: Biozentrum, University of Basel, Switzerland.
authors.forename: Suzette
authors.initials: S
authors.lastname: Mies
authors.affiliation: Biozentrum, University of Basel, Switzerland.
authors.forename: Paul
authors.initials: P
authors.lastname: Jenö
authors.affiliation: Clinical Pharmacology & Toxicology, University Hospital Basel, Switzerland; Department of Biomedicine, University of Basel, Switzerland; Swiss Center of Applied Human Toxicology (SCAHT), Switzerland. Electronic address: kraehenbuehl@uhbs.ch.
authors.forename: Stephan
authors.initials: S
authors.lastname: Krähenbühl
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001553:Benzbromarone / Q000633:toxicity*; D056486:Chemical and Drug Induced Liver Injury / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism / Q000187:drug effects*; D006019:Glycolysis / Q000187:drug effects; D056945:Hep G2 Cells; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D009336:Necrosis; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors
chemical_list: D017382:Reactive Oxygen Species; D019344:Lactic Acid; D001553:Benzbromarone; D000255:Adenosine Triphosphate
keywords: Benzbromarone; Mitochondrial fragmentation; Mitochondrial toxicity; Respiratory chain; β-oxidation