Anti-tumour promoting activity of diphenylmethyl selenocyanate against two-stage mouse skin carcinogenesis.

Epidemiological, clinical and experimental evidence collectively suggests that Se in different inorganic and organic forms provides a potential cancer chemopreventive agent, active against several types of cancer. It can exert preventive activity in all the three stages of cancer: initiation, promotion and progression. Literature reports revealed that organoselenocyanates have more potential as chemopreventive agents than inorganic forms due to their lower toxicity. In our previous report we showed chemopreventive efficacy of diphenylmethyl selenocyanate during the initiation and pre- plus post-initiation phases of skin and colon carcinogenesis process. The present study was undertaken to explore the anti-tumour promoting activity of diphenylmethyl selenocyanate in a 7,12-dimethylbenz (a) anthracene (DMBA)-croton oil two-stage skin carcinogenesis model. The results obtained showed significant (p<0.01) reduction of the incidence and number of skin papillomas, precancerous skin lesions, along with significant (p<0.01) elevation of phase II detoxifying enzymes (GST, Catalase and SOD) and inhibition of lipid peroxidation in liver and skin. Thus, the present data strongly suggest that diphenylmethyl selenocyanate also has the potential to act as anti-tumour promoter agent in a two-stage skin carcinogenesis mouse model, pointing to possible general efficacy.

Inhibition of DMBA-croton oil two-stage mouse skin carcinogenesis by diphenylmethyl selenocyanate through modulation of cutaneous oxidative stress and inhibition of nitric oxide production.

Selenium, an essential micronutrient, plays important roles against different diseases, including several types of cancer. In the present study, antioxidative and chemopreventive properties of a synthetic organoselenium compound, diphenylmethyl selenocyanate, were evaluated with a 7,12-dimethylbenz (a) anthracene - croton oil induced two-stage mouse skin carcinogenesis model. The compound was administered orally to carcinogen-treated mice at two different non-toxic doses, 2mg/kg. b.w. and 3mg/kg. b.w. Significant inhibition in the incidence of papilloma formation (53-80%) as well as in the cumulative numbers of papillomas per papilloma bearing mouse were observed in the treated groups as compared to the carcinogen control group. The compound was also found to upregulate significantly different phase II detoxifying enzymes such as glutathione-S-transferase (p<0.01) and superoxide dismutase (p<0.01) in skin cytosol when measured after 15 days and also after 12 weeks of the first 7,12-dimethylbenz (a) anthracene treatment. Lipid peroxidation measured with reference to thiobarbituric acid reactive substances in skin microsomes was significantly inhibited (p<0.05) in a dose dependent manner by diphenylmethyl selenocyanate. Considerable inhibition of the level of nitric oxide production in peritoneal macrophages was observed after 12 weeks (p<0.05). Thus the compound appears to exert chemopreventive activity in terms of papilloma formation, which may be through modulation of cutaneous lipid peroxidation, the phase II detoxifying enzyme system and nitric oxide production.