Geraniin-mediated apoptosis by cleavage of focal adhesion kinase through up-regulation of Fas ligand expression in human melanoma cells

Mol Nutr Food Res. 2008 Jun;52(6):655-63. doi: 10.1002/mnfr.200700381.

Abstract

Geraniin, a form of tannin separated from geranium, causes cell death through induction of apoptosis; however, cell death characteristics for geraniin have not yet been elucidated. Here, we investigated the mechanism of geraniin-induced apoptosis in human melanoma cells and demonstrated that geraniin was able to induce cell apoptosis in a concentration- and time-dependent manner. We also examined the signaling pathway related to geraniin-induced apoptosis. To clarify the relationship between focal adhesion kinase (FAK) and geraniin-induced apoptosis, we treated human melanoma cells with geraniin and found that this resulted dose- and time-dependent degradation in FAK. However, FAK cleavage was significantly inhibited when cells were pretreated with a selective inhibitor of caspase-3 (Ac-Asp-Glu-Val-Asp-CHO). Here, we demonstrated for the first time that geraniin triggered cell death by caspase-3-mediated cleavage of FAK. There were two possible mechanisms for activating caspase-3, mitochondria-mediated and receptor-mediated apoptosis. To confirm the geraniin-relevant signaling pathway, using immunoblot analysis we found that geraniin-induced apoptosis was associated with the up-regulation of Fas ligand expression, the activation of caspase-8, the cleavage of Bid, and the induction of cytochrome c release from mitochondria to the cytosol. Treatment with geraniin caused induction of caspase-3 activity in a dose- and time-dependent manner followed by proteolytic cleavage of poly-(ADP-ribose) polymerase, and DNA fragmentation factor 45. The geraniin-induced apoptosis may provide a pivotal mechanism for its cancer-chemopreventive action.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anticarcinogenic Agents / pharmacology
  • Apoptosis / drug effects*
  • BH3 Interacting Domain Death Agonist Protein / metabolism
  • Caspase 8 / metabolism
  • Caspase Inhibitors
  • Cell Line, Tumor
  • Cytochromes c / metabolism
  • Enzyme Activation / drug effects
  • Enzyme Inhibitors / pharmacology
  • Fas Ligand Protein / genetics*
  • Focal Adhesion Protein-Tyrosine Kinases / metabolism*
  • Glucosides / metabolism
  • Glucosides / pharmacology*
  • Humans
  • Hydrolyzable Tannins / metabolism
  • Hydrolyzable Tannins / pharmacology*
  • Melanoma / metabolism*
  • Up-Regulation / drug effects*

Substances

  • Anticarcinogenic Agents
  • BH3 Interacting Domain Death Agonist Protein
  • Caspase Inhibitors
  • Enzyme Inhibitors
  • Fas Ligand Protein
  • Glucosides
  • Hydrolyzable Tannins
  • Geraniin
  • Cytochromes c
  • Focal Adhesion Protein-Tyrosine Kinases
  • Caspase 8