Butylated hydroxyanisole (
BHA), a commonly used food preservative, is reported to have anticarcinogenic properties in some animal models. However, the use of
BHA as a chemopreventive agent against
cancer in human has been challenged by the observation that
BHA may exert toxic effect in some tissues of animals. Therefore, it is of great significance to understand the mechanism of
BHA-induced toxicity. Here, we report that
BHA induces apoptosis in freshly isolated rat hepatocytes. Treatment of hepatocytes with
BHA also induced loss of mitochondrial transmembrane potential (Deltapsi(m)),
cytochrome c, and activation of
caspase-3, -8, and -9 but not caspase-1. Pretreatment with
cyclosporin A, an agent that stabilizes
mitochondrial permeability transition pore, inhibited
BHA-induced loss of Deltapsi(m),
cytochrome c release,
caspase activation, and apoptosis. Interestingly,
benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl
ketone failed to prevent these mitochondrial events, although it blocked
caspase activation and apoptosis. Furthermore,
BHA-induced apoptosis appeared to be independent of formation of reactive intermediates, as evidenced by the lack of effects of
antioxidants N-acetyl-L-cysteine and
ascorbic acid. Indeed, direct incubation of
BHA with isolated mitochondria triggered
cytochrome c release. Thus, these results indicate that the cytotoxicity of
BHA is due to the induction of apoptosis that is mediated by the direct release of
cytochrome c and the subsequent activation of
caspases.