Apoptosis measured employing semi-quantitative and quantitative assays, and parameters showed good agreement in direction and extent of change that appears to be one of the major contributors in disappearance of BPDE-DNA adducts in tissues studied. Quantitative analysis and comparison of IHC staining measuring BPDE-DNA adducts and apoptosis in tissue sections have the advantage that preceding or subsequent paraffin-embedded sections from the same portion of the tissue are

compared, and this comparison is likely to be relevant and meaningful. Curcumin-mediated enhancement of apoptosis in B(a)P-treated (normal liver and lung tissues) cells has some similarity with its effects in terms of apoptosis observed in transformed or immortalized cells in culture [23], [24] and [25]. To our knowledge, this is an initial in vivo report demonstrating that dietary curcumin augmented the expression of caspase-3 Talazoparib price and increased the Bax/Bcl-2

find more ratio and a apoptotic index in normal cells in response to B(a)P-induced DNA damage. This in turn probably accounts for the enhanced disappearance of adduct containing nuclei although the degree of responses varied. The other potential contributor in observed relative decrease in BPDE-DNA adducts is cell proliferation, and its role was assessed by comparing the levels of PCNA by western blot analysis. It was seen from experiment 1 that levels of PCNA were enhanced post B(a)P-treatment especially Elongation factor 2 kinase at later time points [subgroups BP(+96h) and BP(+144h)], and B(a)P-mediated

increases were significantly decreased by dietary curcumin when compared to time-matched B(a)P-treated controls in liver [subgroups BP(+96 h) + C 72 h, BP(+144 h) + C 120 h] and lungs [BP(+144 h) + C 120 h]. In experiment 2, levels of PCNA were not altered significantly at 8-28 days post B(a)P [BP(+8d), BP(+15d), BP(+29d)] both in the liver and lungs while curcumin treatment resulted in significant increase in the levels of PCNA in liver [subgroups BP(+8d) + C 7d, BP(+29d) + C 28d] and lungs [BP(+15d) + C 14d, BP(+29d) + C 28d]. It may be noted that exposure to dietary curcumin alone does not alter the levels of PCNA in liver and lungs of mice. After considering and comparing the slope of time-related and curcumin-mediated changes in BPDE-DNA adducts and numbers of cells undergoing apoptosis and cell proliferation, it is seen that the observed decrease in BPDE-DNA adducts in experiment 1 is mainly attributed to curcumin-mediated enhanced apoptosis. In experiment 2 dilution of BPDE-DNA adducts by newly synthesized non-adducted DNA due to cell proliferation appears to be the reason (Figure 3, Figure 5 and Figure 8). In both these experiments, apoptosis (experiment 1) and cell proliferation (experiment 2) alone may not be sufficient to result in the extent of decrease as potential contribution of DNA-repair may also be included.