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 M 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 M 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 (⌬⌿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 ϳ80%, 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 mitochondial redox-sensitive mechanism.

Anti-angiogenic effects of dietary isothiocyanates: Mechanisms of action and implications for human health

“…5 M (PEITC) [93] 10 M (PEITC) [94] 5 M (SFN) [90] 15 M (SFN) [91] 5 M (BITC) [43] 10 M (PEITC) [95] Induction of Appears to require higher concentrations 25 M (PEITC/BITC) A c c e p t e d M a n u s c r i p t necrosis than induction of apoptosis [96] 50 m (BITC) [97] Metastasis ITCs inhibit cell adhesion, invasion and migration in vitro, and metastasis in vivo 5 M (AITC) [98] 5 M (PEITC) [99] 2 M (PEITC) [24] 2 g/ml (SFN) [100] Inhibition of angiogenesis ITCs inhibit angiogenesis in in vitro and in vivo models 1 M (PEITC) [24] 5 g/ml (AITC) [27] 0.1 -1 M (SFN) [23] Page 30 of 38…”

Curcumin induces mitochondria pathway mediated cell apoptosis in A549 lung adenocarcinoma cells

“…These results suggest that the decrease of mitochondrial membrane potential and increase of cytochrome c release may be due to the alteration in the mitochondria structure. In addition, the mitochondrial swelling and disruption have also been reported in various types of tumor cells exposed to other putative cancer chemopreventive agents during apoptosis (32,33), suggesting that the change of mitochondrial function and structure observed during curcumin-induced apoptosis in A549 cells was perhaps not an agent-or cell type-specific phenomenon.…”

Curcumin induces apoptosis in human lung adenocarcinoma A549 cells through a reactive oxygen species-dependent mitochondrial signaling pathway

“…The results showed that curcumin induced loss of mitochondrial membrane potential in a dose-dependent manner. In addition, the loss of MMP has also been reported in various types of tumor cells exposed to other putative cancer chemopreventive agents during apoptosis (19,20). These would suggest that the change of mitochondrial function observed during curcumin-induced apoptosis in A549 cells was perhaps not an agent-or cell type-specific phenomenon.…”