title: Cooperative interaction of benzo[a]pyrene and ethanol on plasma membrane remodeling is responsible for enhanced oxidative stress and cell death in primary rat hepatocytes.
abstract: Several epidemiologic studies have shown an interactive effect of heavy smoking and heavy alcohol drinking on the development of hepatocellular carcinoma. It has also been recently described that chronic hepatocyte death can trigger excessive compensatory proliferation resulting later in the formation of tumors in mouse liver. As we previously demonstrated that both benzo[a]pyrene (B[a]P), an environmental agent found in cigarette smoke, and ethanol possess similar targets, especially oxidative stress, to trigger death of liver cells, we decided to study here the cellular and molecular mechanisms of the effects of B[a]P/ethanol coexposure on cell death. After an 18-h incubation with 100nM B[a]P, primary rat hepatocytes were supplemented with 50mM ethanol for 5 or 8h. B[a]P/ethanol coexposure led to a greater apoptotic cell death that could be linked to an increase in lipid peroxidation. Plasma membrane remodeling, as depicted by membrane fluidity elevation and physicochemical alterations in lipid rafts, appeared to play a key role, because both toxicants acted with specific complementary effects. Membrane remodeling was shown to induce an accumulation of lysosomes leading to an important increase in low-molecular-weight iron cellular content. Finally, ethanol metabolism, but not that of B[a]P, by providing reactive oxygen species, induced the ultimate toxic process. Indeed, in lysosomes, ethanol promoted the Fenton reaction, lipid peroxidation, and membrane permeabilization, thereby triggering cell death. To conclude, B[a]P exposure, by depleting hepatocyte membrane cholesterol content, would constitute a favorable ground for a later toxic insult such as ethanol intoxication. Membrane stabilization of both plasma membrane and lysosomes might be a potential target for further investigation considering cytoprotective strategies.
authors.affiliation: UMR INSERM 1085, IRSET, UFR des Sciences Pharmaceutiques et Biologiques, and 35043 Rennes Cédex, France; Biosit UMS3080, Université de Rennes 1, 35043 Rennes Cédex, France.
authors.forename: Aurore
authors.initials: A
authors.lastname: Collin
authors.affiliation: UMR INSERM 1085, IRSET, UFR des Sciences Pharmaceutiques et Biologiques, and 35043 Rennes Cédex, France; Biosit UMS3080, Université de Rennes 1, 35043 Rennes Cédex, France.
authors.forename: Kevin
authors.initials: K
authors.lastname: Hardonnière
authors.affiliation: UMR INSERM 1085, IRSET, UFR des Sciences Pharmaceutiques et Biologiques, and 35043 Rennes Cédex, France; Biosit UMS3080, Université de Rennes 1, 35043 Rennes Cédex, France.
authors.forename: Martine
authors.initials: M
authors.lastname: Chevanne
authors.affiliation: UMR INSERM 1085, IRSET, UFR des Sciences Pharmaceutiques et Biologiques, and 35043 Rennes Cédex, France; Biosit UMS3080, Université de Rennes 1, 35043 Rennes Cédex, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Vuillemin
authors.affiliation: UMR INSERM 1085, IRSET, UFR des Sciences Pharmaceutiques et Biologiques, and 35043 Rennes Cédex, France; Biosit UMS3080, Université de Rennes 1, 35043 Rennes Cédex, France.
authors.forename: Normand
authors.initials: N
authors.lastname: Podechard
authors.affiliation: Biosit UMS3080, Université de Rennes 1, 35043 Rennes Cédex, France.
authors.forename: Agnès
authors.initials: A
authors.lastname: Burel
authors.affiliation: UMR INSERM 1085, IRSET, UFR des Sciences Pharmaceutiques et Biologiques, and 35043 Rennes Cédex, France; Biosit UMS3080, Université de Rennes 1, 35043 Rennes Cédex, France.
authors.forename: Marie-Thérèse
authors.initials: MT
authors.lastname: Dimanche-Boitrel
authors.affiliation: UMR INSERM 1085, IRSET, UFR des Sciences Pharmaceutiques et Biologiques, and 35043 Rennes Cédex, France; Biosit UMS3080, Université de Rennes 1, 35043 Rennes Cédex, France. Electronic address: dominique.lagadic@univ-rennes1.fr.
authors.forename: Dominique
authors.initials: D
authors.lastname: Lagadic-Gossmann
authors.affiliation: UMR INSERM 1085, IRSET, UFR des Sciences Pharmaceutiques et Biologiques, and 35043 Rennes Cédex, France; Biosit UMS3080, Université de Rennes 1, 35043 Rennes Cédex, France. Electronic address: osergent@univ-rennes1.fr.
authors.forename: Odile
authors.initials: O
authors.lastname: Sergent
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001564:Benzo(a)pyrene / Q000633:toxicity*; D002273:Carcinogens / Q000633:toxicity; D002462:Cell Membrane / Q000187:drug effects*; D002492:Central Nervous System Depressants / Q000633:toxicity; D000431:Ethanol / Q000633:toxicity*; D022781:Hepatocytes / Q000187:drug effects* / Q000473:pathology; D015227:Lipid Peroxidation / Q000187:drug effects; D008247:Lysosomes / Q000187:drug effects; D046529:Microscopy, Electron, Transmission; D018384:Oxidative Stress / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D002273:Carcinogens; D002492:Central Nervous System Depressants; D001564:Benzo(a)pyrene; D000431:Ethanol
keywords: Benzo[a]pyrene; Ethanol; Iron; Lipid rafts; Liver; Lysosome; Membrane fluidity; Oxidative stress; Primary rat hepatocytes; Reactive oxygen species