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Open Access Highly Accessed Research article

Capsaicin induces cell cycle arrest and apoptosis in human KB cancer cells

Chia-Han Lin1, Wei-Cheng Lu2, Che-Wei Wang1, Ya-Chi Chan2 and Mu-Kuan Chen1*

Author Affiliations

1 Department of Otorhinolaryngology, Head and Neck Surgery, Changhua Christian Hospital, 135 Nanhsiao St, Changhua, Taiwan

2 Cancer Research Center, Changhua Christian Hospital, Changhua, Taiwan

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BMC Complementary and Alternative Medicine 2013, 13:46  doi:10.1186/1472-6882-13-46

Published: 25 February 2013

Abstract

Background

Capsaicin, a pungent phytochemical in a variety of red peppers of the genus Capsicum, has shown an anti-proliferative effect on various human cancer cell lines. In contrast, capsaicin has also been considered to promote the growth of cancer cells. Thus, the effects of capsaicin on various cell types need to be explored. The anti-proliferative effects of capsaicin on human KB cancer cells are still unknown. Therefore, we examined the viability, cell cycle progression, and factors associated with apoptosis in KB cells treated with capsaicin.

Methods

The cell proliferation/viability and cytotoxicity of KB cells exposed to capsaicin were determined by a sulforhodamine B colorimetric assay and trypan blue exclusion. Apoptosis was detected by Hoechst staining and confirmed by western blot analysis of poly-(ADP-ribose) polymerase cleavage. Cell cycle distribution and changes of the mitochondrial membrane potential were analyzed by flow cytometry. Furthermore, the expression of caspase 3, 8 and 9 was evaluated by immunoblotting.

Results

We found that treatment of KB cells with capsaicin significantly reduced cell proliferation/viability and induced cell death in a dose-dependent manner compared with that in the untreated control. Cell cycle analysis indicated that exposure of KB cells to capsaicin resulted in cell cycle arrest at G2/M phase. Capsaicin-induced growth inhibition of KB cells appeared to be associated with induction of apoptosis. Moreover, capsaicin induced disruption of the mitochondrial membrane potential as well as activation of caspase 9, 3 and poly-(ADP-ribose) polymerase in KB cells.

Conclusions

Our data demonstrate that capsaicin modulates cell cycle progression and induces apoptosis in human KB cancer cells through mitochondrial membrane permeabilization and caspase activation. These observations suggest an anti-cancer activity of capsaicin.

Keywords:
Capsaicin; KB cells; Cell cycle; Apoptosis; Mitochondria