Antitumor effect of 1, 8-cineole against colon cancer.

Several essential oils possess pharmacological effects. Among the various constituents of essential oils, 1, 8-cineole has been shown to possess pharmacological effects such as anti-bacterial and anti-inflammatory effects. The effect of 1, 8-cineole on human colorectal cancer cells, however, has not reported previously. In this study, we have investigated the anti-proliferative effect of 1, 8-cineole on human colon cancer cell lines HCT116 and RKO by WST-8 and BrdU assays. The cytotoxicity of 1, 8-cineole was investigated by LDH activity and TUNEL staining. The mechanism of apoptosis by 1, 8-cineole was determined by western blot analyses. In in vivo study, RKO cells were injected into the SCID mice and the effect of 1, 8-cineole was investigated. Specific induction of apoptosis, not necrosis, was observed in human colon cancer cell lines HCT116 and RKO by 1, 8-cineole. The treatment with 1, 8-cineole was associated with inactivation of survivin and Akt and activation of p38. These molecules induced cleaved PARP and caspase-3, finally causing apoptosis. In xenotransplanted SCID mice, the 1, 8-cineole group showed significantly inhibited tumor progression compared to the control group. These results indicated 1, 8-cineole suppressed human colorectal cancer proliferation by inducing apoptosis. Based on these studies 1, 8-cineole would be an effective strategy to treat colorectal cancer.