Involvement of the mitochondrial death pathway in chemopreventive benzyl isothiocyanate-induced apoptosis.

Abstract

In the present study, we studied the molecular mechanism underlying cell death induced by a cancer chemoprotective compound benzyl isothiocyanate (BITC). The cytotoxic effect of BITC was examined in rat liver epithelial RL34 cells. Apoptosis was induced when the cells were treated with 20 mum BITC, characterized by the appearance of phosphatidylserine on the outer surface of the plasma membrane and caspase-3 activation, whereas no caspase activation and propidium iodide incorporation into cell were detected with 50 mum BITC that induced necrosis. The mitochondrial death pathway was suggested to be involved in BITC-induced apoptosis because the treatment of cells with BITC-induced caspase-9-dependent apoptosis and mitochondrial transmembrane potential (Delta Psi m) alteration. We demonstrated here for the first time that BITC directly modifies mitochondrial functions, including inhibition of respiration, mitochondrial swelling, and release of cytochrome c. Moreover, glutathione depletion by diethyl maleate significantly accelerated BITC-triggered apoptosis, suggesting the involvement of a redox-dependent mechanism. This was also implicated by the observations that intracellular accumulation of reactive oxygen species, including superoxide (O(2)) and hydroperoxides (HPOs), was indeed detected in the cells treated with BITC and that the intracellular HPO level was significantly attenuated by pretreatment with N-acetylcysteine. The treatment with a pharmacological scavenger of O(2), Tiron, also diminished the HPO formation by approximately 80%, suggesting that most of the HPOs were H(2)O(2) derived from the dismutation of O(2). These results suggest that BITC induces apoptosis through a mitochondrial redox-sensitive mechanism.

• Authors: Yoshimasa Nakamura, Makiko Kawakami, Akira Yoshihiro, Noriyuki Miyoshi, Hajime Ohigashi, Kiyoshi Kawai, Toshihiko Osawa, Koji Uchida
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 277 Issue 10 Pg. 8492-9 (Mar 08 2002) ISSN: 0021-9258 [Print] United States
• PMID: 11751909 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anticarcinogenic Agents
• Cytochrome c Group
• Isothiocyanates
• Phosphatidylserines
• Reactive Oxygen Species
• benzyl isothiocyanate
• Casp3 protein, rat
• Caspase 3
• Caspases

Topics

• Animals
• Anticarcinogenic Agents (pharmacology)
• Apoptosis
• Caspase 3
• Caspases (metabolism)
• Cell Death (drug effects)
• Cell Line
• Cell Membrane (metabolism)
• Cells, Cultured
• Cytochrome c Group (metabolism)
• Dose-Response Relationship, Drug
• Enzyme Activation
• Epithelial Cells (drug effects)
• Flow Cytometry
• Isothiocyanates (pharmacology)
• Liver (cytology, drug effects)
• Membrane Potentials
• Mitochondria (metabolism, pathology)
• Necrosis
• Oxidation-Reduction
• Phosphatidylserines (metabolism)
• Rats
• Reactive Oxygen Species (metabolism)
• Time Factors