Curcumin and quercetin trigger apoptosis during benzo(a)pyrene-induced lung carcinogenesis

The aim of the present study was to assess the cumulative effects of curcumin and quercetin in inducing apoptosis during benzo(a)pyrene (BP) (100 mg/Kg body weight)-induced lung carcinogenesis in mice. BP treatment resulted in a significant increase in the protein expression of Bcl-2 whereas expression of Bax was significantly decreased. Further, BP treatment brought about a significant decrease in the activities of caspase 3, caspase 9 as well as the number of apoptotic cells. Interestingly, separate as well as combined supplementation of curcumin (60 mg/kg body weight) and quercetin (40 mg/kg body weight) to BP-treated animals resulted in a significant decrease in the protein expression of Bcl-2 but caused a significant increase in the protein expression of Bax along with a noticeable improvement in the number of apoptotic cells. Also, supplementation with curcumin and quercetin separately to BP-treated mice brought a significant improvement in the enzyme activities of caspase 9 as well as caspase 3 but the improvement was more pronounced following combined treatment. Therefore, curcumin and quercetin, if given in combination shall exhibit enhanced chemopreventive potential against development of lung carcinogenesis by stimulating the apoptotic machinery.