Capsaicin-induced apoptosis in human breast cancer MCF-7 cells through caspase-independent pathway.

Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide), a significant pungent ingredient in a variety of red peppers of the genus Capsicum, is a type of vanilloid. It has been shown to exert biological activities (anticarcinogenic, antimutagenic and chemopreventive) in many cancer cell lines. It was found that capsaicin induces dose-dependent growth inhibition of MCF-7 cells, which does not express caspase-3. In this study, we investigated the molecular mechanism of capsaicin-induced apoptosis in MCF-7 cells. Treatment with capsaicin for 24 h resulted in dose-dependent apoptosis in these cells. After the addition of capsaicin, the levels of reactive oxygen species were reduced slightly in the earlier stage of treatment. Interestingly, an elevation of intracellular calcium ion concentration was detected in the MCF-7 cells. In time course and dosage studies, the mitochondrial membrane potential of MCF-7 cells decreased. However, the change was not significant. It is worth noting that the apoptosis-inducing factor translocated into the cytosol and nucleus from the mitochondria. Our results suggest that capsaicin induces cellular apoptosis through a caspase-independent pathway in MCF-7 cells, and that reactive oxygen species and intracellular calcium ion fluctuation has a minimal role in the process.