The present study has investigated the modulating effect of carnosic acid on the expression pattern of cell proliferative (proliferating cell nuclear antigen (PCNA) cyclin D1 and a transcription factor c-fos), apoptotic (p53, Bcl-2, Bax caspase -3 and 9), inflammatory (Nuclear factor kappa B (NFκB) and cyclooxygenase-2 (COX-2) and angiogenic (vascular endothelial growth factor (VEGF) markers during 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch carcinogenesis. Oral tumors were developed in the hamsters buccal pouches by painting with 0.5% DMBA in liquid paraffin three times a week for 14 weeks. Hundred per cent tumour formation (well-differentiated squamous cell carcinoma) accompanied by deregulation in the above mentioned molecular markers was noticed in hamsters treated with DMBA alone (tumour bearing hamsters). Oral administration of carnosic acid at dose of 10mg/kg bw to hamsters treated with DMBA not only completely prevented the tumour formation, but also corrected the abnormalities in the expression pattern of molecular markers. The present study suggests that carnosic acid might have inhibited the tumour formation by exerting anti-cell-proliferative, anti-inflammatory, anti-angiogenic and apoptotic potential during DMBA-induced hamster buccal pouch carcinogenesis.

Apoptosis, also known as cell suicide or programmed cell death, removes unwanted and genetically damaged cells from the body. Evasion of apoptosis is one of the major characteristic features of rapidly proliferating tumor cells. Chemopreventive agents inhibit or suppress tumor formation through apoptotic induction in target tissues. The aim of the present study was to investigate the pro-apoptotic potential of lupeol during 7,12-dimethylbenz(a) anthracene (DMBA) induced hamster buccal pouch carcinogenesis. Topical application of 0.5% DMBA three times a week for 14 weeks in the buccal pouches of golden Syrian hamsters resulted in oral squamous cell carcinoma. The expression pattern of apoptotic markers was analyzed using immunohistochemistry (p53, Bcl-2, Bax) and ELISA reader (caspase 3 and 9). In the present study, 100% tumor formation with defects in apoptotic markerexpression pattern was noticed in hamsters treated with DMBA alone. Oral administration of lupeol at a dose of 50mg/kg bw completely prevented the formation oral tumors as well as decreased the expression p53 and Bcl-2, while increasing the expression of Bax and the activities of caspase 3 and 9. The present study thus indicated that lupeol might inhibit DMBA-induced oral tumor formation through its pro-apoptotic potential in golden Syrian hamsters.

The oral cancer chemopreventive efficacy of lupeol, a bioactive triterpene, was assessed by monitoring the tumor incidence and using the status of phase I and II xenobiotic metabolizing enzymes, lipid peroxidation and antioxidants as biochemical end points during 7,12-dimethylbenz(a)anthracene (DMBA) induced hamster buccal pouch carcinogenesis. Oral tumors were developed in the buccal pouch of golden Syrian hamsters by painting with 0.5 % DMBA three times a week for 14 weeks. Well differentiated oral squamous cell carcinoma with marked abnormalities in the status of biochemical markers were noticed in hamsters treated with DMBA alone. Oral administration of lupeol at a dose of 50 mg/kg bw completely inhibited the formation of oral tumors and restored the status of biochemical markers during DMBA induced oral carcinogenesis. The present study thus demonstrates the chemopreventive potential of lupeol in DMBA induced oral carcinogenesis. The chemopreventive potential of lupeol is probably due to its antioxidant or free radical scavenging property and modulating effect on phase I and II xenobiotic metabolizing enzymes in favour of the excretion of carcinogenic metabolites during DMBA induced hamster buccal pouch carcinogenesis.