Thearubigins/Polymeric black tea polyphenols (PBPs) do not prevent benzo[a]pyrene (B[a]P) induced lung tumors in A/J...

Previously we have demonstrated the chemopreventive effect of Thearubigins/Polymeric Black-tea Polyphenols (PBPs) upon pre-treatment to a combination of carcinogens, that is, Benzo[a]pyrene (B[a]P) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) which are present in Tobacco smoke (TS). However, the chemopreventive effect in response to B[a]P as a single carcinogen remains unexplored. B[a]P is a universal carcinogen and an important constituent of particulate matter 2.5 (PM_2.5) found in the environment and in TS.

We investigated the pre-treatment of Thearubigins/PBPs as a chemopreventive agent at three doses (1.5, 5, 10%) against B[a]P-induced lung carcinogenesis at early & late time points. We also investigated the effect of PBPs at early time points to understand molecular changes by employing western blotting in xenobiotic metabolism pathways, DNA damage, inflammation, apoptosis, and proliferation as they are modulated in response to carcinogens. We used 6-8 weeks male A/J mice for tumorigenicty and western blotting to probe the molecular biomarkers.

We report no decrease in tumor incidence and multiplicity upon pre and concurrent treatment of Thearubigins/PBPs. Further, we also report no changes in molecular markers at early time points, in agreement with former observations.

Our results suggest that chemopreventive agents need to be tested with different combinations of carcinogens and regimens to fully understand the complex interplay between carcinogenesis and the efficacy of chemopreventive agents. Studies like these will provide meaningful data before initiating large-scale clinical trials.