Effects of chemopreventive agents on DNA damage response

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DESCRIPTION (provided by applicant): Benzo[a]pyrene (B[a]P) is a prototypical polycyclic aromatic hydrocarbon produced by incomplete combustion and is a major carcinogen present in cigarette smoke and charred foods. PAH such as B[a]P are major environmental pollutants and exposure is widespread. The highly reactive and mutagenic B[a]P metabolite (+)-7R,8S-dihydroxy-9S,10R-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE) is believed to play a significant role in human lung carcinogenesis. Chemoprevention is a relatively new and promising strategy to prevent cancer. Chemopreventive agents such as genistein, curcumin and resveratrol have a number of molecular targets, impact several signalling pathways and have strong antiproliferation effects on lung, breast, prostate and colon cancers. These three constituents have received a great deal of attention recently as cancer chemoprotective agents. Little work has been done to investigate the chemoprevention effects of genistein, resveratrol and curcumin with respect to PAH-induced DNA damage and repair responses. The global genomic repair component of nucleotide excision repair is regulated by p53 induction in response to DNA damage. P53 is induced in a dose and time-dependent manner after DNA damage. Low dose BPDE which is known to be mutagenic fails to induce the p53 mediated response to DNA damage. Our preliminary results suggest that pretreatment with a combination of resveratrol and curcumin enables p53 induction by low dose BPDE exposure. We hypothesize that chemopreventive agents may "sensitize" the cell to respond to low dose genotoxicant induced DNA damage through induction of p53 which activates global genomic DNA repair process allowing more efficient DNA repair. This study aims to investigate the effects of chemoprevention agents on cellular responses to BPDE-induced DNA damage in human lung cells. We aim to determine mechanism and effects of chemopreventive agents (singly and in combination) on p53 mediated regulation of (1) cell cycle progression and (2) DNA repair induction. Experimental approaches will include western blot to measure p53 and regulated signaling proteins in human lung cells and measure BPDE-induced DNA adduct formation and repair rate by 32P-post-labeling analyses. The results will likely illuminate a chemoprevention mechanism and also provide a deeper understanding of the mechanism of DNA damage and repair under a more physiologically relevant environmental exposure dose.