A new lactoferrin- and iron-dependent lysosomal death pathway is induced by benzo[a]pyrene in hepatic epithelial cells

Toxicol Appl Pharmacol. 2008 Apr 15;228(2):212-24. doi: 10.1016/j.taap.2007.12.021. Epub 2008 Jan 3.

Abstract

While lysosomal disruption seems to be a late step of necrosis, a moderate lysosomal destabilization has been suggested to participate early in the apoptotic cascade. The origin of lysosomal dysfunction and its precise role in apoptosis or apoptosis-like process still needs to be clarified, especially upon carcinogen exposure. In this study, we focused on the implication of lysosomes in cell death induced by the prototype carcinogen benzo[a]pyrene (B[a]P; 50 nM) in rat hepatic epithelial F258 cells. We first demonstrated that B[a]P affected lysosomal morphology (increase in size) and pH (alkalinization), and that these changes were involved in caspase-3 activation and cell death. Subsequently, we showed that lysosomal modifications were partly dependent on mitochondrial dysfunction, and that lysosomes together with mitochondria participate in B[a]P-induced oxidative stress. Using two iron chelators (desferrioxamine and deferiprone) and siRNA targeting the lysosomal iron-binding protease lactoferrin, we further demonstrated that both lysosomal iron content and lactoferrin were required for caspase-3 activation and apoptosis-like cell death.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acridine Orange / pharmacology
  • Animals
  • Apoptosis / drug effects*
  • Benzo(a)pyrene / chemistry
  • Benzo(a)pyrene / toxicity*
  • Carcinogens / chemistry
  • Carcinogens / toxicity
  • Caspase 3 / metabolism
  • Cell Line
  • Cell Size / drug effects
  • Deferiprone
  • Deferoxamine / pharmacology
  • Dose-Response Relationship, Drug
  • Epithelial Cells / drug effects*
  • Epithelial Cells / metabolism
  • Epithelial Cells / ultrastructure
  • Iron / antagonists & inhibitors
  • Iron / metabolism*
  • Iron Chelating Agents / pharmacology
  • Lactoferrin / genetics
  • Lactoferrin / metabolism*
  • Liver / cytology
  • Lysosomes / drug effects*
  • Lysosomes / metabolism
  • Microscopy, Electron
  • Models, Biological
  • Oxidative Stress / drug effects
  • Pyridones / pharmacology
  • RNA, Small Interfering / genetics
  • Rats
  • Transfection

Substances

  • Carcinogens
  • Iron Chelating Agents
  • Pyridones
  • RNA, Small Interfering
  • Deferiprone
  • Benzo(a)pyrene
  • Iron
  • Lactoferrin
  • Caspase 3
  • Acridine Orange
  • Deferoxamine