Chemopreventive effects of curcumin and green tea on B[a]P-induced carcinogenesis in the hamster cheek pouch

The present study was carried out to examine the chemopreventive effects of curcumin and green tea polyphenols on the hamster cheek pouch carcinogenesis model. This model of oral carcinogenesis has been widely used in chemoprevention studies, however, these studies have been limited to the use of DMBA as the carcinogenic agent. We have developed a protocol of carcinogenesis in the hamster cheek pouch using B[a]P, a broadly distributed environmental carcinogen, formed as a by-product of the combustion of organic materials including cigarette smoke. B[a]P- induced tumors in the hamster cheek pouch are primarily endophytic squamous cell carcinomas that closely resemble squamous cell carcinomas of the human oral mucosa. The cheek pouch of male Syrian hamsters were treated topically for eight weeks with 0.6% curcumin, 6.0% curcumin, 2.5% green tea polyphenols, or 5.0% green tea polyphenols, 3 times per week 30 minutes prior to the application of 2.0% B[a]P. The animals were sacrificed 24 hours and 72 hours after the last treatments. Short-term mechanistic markers of malignant progression were used to determine effects of each compound. Cellular proliferation, assessed by bromodeoxyuridine (Brdu) incorporation, p53 protein accumulation, and apoptotic activity were evaluated. The results of the present study demonstrated that 0.6% curcumin and 2.5% green tea polyphenols had strong inhibitory effects on cellular proliferation and p53 protein accumulation. And 6.0% curcumin and 5.0% green tea polyphenols appeared to induce apoptosis. Our data suggest that curcumin and green tea polyphenols may have a plausible chemopreventive effect on oral carcinogenesis in the hamster cheek pouch model.