Dietary curcumin post-treatment enhances the disappearance of B(a)P-derived DNA adducts in mouse liver and lungs

To study the post-treatment effects of dietary curcumin on the levels of benzo(a)pyrene [B(a)P]-induced DNA adducts, mice were administered oil or B(a)P and randomized into 7 subgroups after 24 h. One of the subgroups from both the oil and B(a)P groups was killed at 24 h while the remaining 6 subgroups were shifted to powdered control or 0.05% curcumin diet and killed after 24, 72 and 120 h (experiment 1), and 7, 14, and 28 days (experiment 2). Quantitative comparisons of BPDE-DNA nuclear adducts (area and intensity) in immunohistochemically stained lungs and liver sections was carried out by IHC profiler. A time-dependent decrease in the levels of adducts in B(a)P-treated animals was further enhanced by curcumin exposure compared to the levels in time-matched controls. To assess the contribution of apoptosis and cell proliferation in observed curcumin-mediated enhanced decrease of BPDE-DNA adducts, comparative evaluation of apoptosis and cell proliferation markers was undertaken. Results suggested enhancement of B(a)P-induced apoptosis in liver and lungs by curcumin during 24-120 h while no such enhancement was observed at 7-28 days. Results suggest curcumin-mediated enhancement in apoptosis (experiment 1) and adduct dilution (experiment 2) to be the reason for the observed higher decrease of BPDE-DNA adducts.