Although
isothiocyanates have been shown to inhibit
carcinogen-induced
tumorigenesis, no studies have been made to determine their therapeutic potential for the treatment of
breast cancer. In the present study, we evaluated the apoptotic activities of
phenethyl isothiocyanate (
PEITC) in human
breast cancer MCF-7 cells. Exposure to
PEITC potently reduced cell viability. In addition,
DNA fragments and TUNEL positive nuclei were detected in
PEITC-treated cells. Furthermore,
PEITC induced apoptosis via activation of
caspases 7 and 9 and the cleavage of PARP, and these effects were reversed by treatment with the
caspase inhibitor,
Z-VAD-fmk.
PEITC also caused a decrease in the levels of Bcl-2 with a concomitant increase in Bax levels, which resulted in the release of
cytochrome c. XIAP suppression and Smac translocation also contributed to the
PEITC-induced apoptosis. However,
PEITC did not increase the expressions of p53 and p21. Taken together, the results of this study demonstrate that
PEITC significantly induces apoptosis via a mitochondrial pathway. Specifically,
PEITC induced a change in the Bax/Bcl-2 ratios, XIAP levels and Smac translocation that was conjunction with the release of
cytochrome c and following
caspase activation. Therefore,
PEITC has the potential for use as a therapeutic agent for the treatment of
breast cancer.