DescriptionThe cancer chemoprevention is the strategy of blocking or slowing the onset of premalignant tumors and decreases the incidence of cancer with relatively nontoxic chemical substance. More importantly, Nrf2 and Nrf2-antioxidant response element (ARE) pathway plays a critical role in the cancer chemoprevention. Studies of the induction of Nrf2 and subsequent phase II detoxifying/antioxidant drug metabolism enzymes expression by phytochemicals in vivo or in vitro are considered as a major topic. This thesis will focus on the factors important in the regulation of Nrf2 and phase II xenobiotic metabolizing enzymes which are generally considered as antioxidant and detoxifying enzymes in cancer chemoprevention. Accumulating evidence from epidemiological studies indicates that chronic inflammation and oxidative stress play critical roles in neoplastic development. Our results show that tea Chrysanthemun zawadskii (CZ) and licorice Glycyrrhiza uralensis (LE) extracts exhibited potent anti-inflammatory activities by suppressing the mRNA and protein expression levels of pro-inflammatory biomarkers and the NF-kB luciferase activity. Both extracts also showed strong inhibitory effects against NF-kB-mediated inflammatory as well as strong activation of the Nrf2-ARE-antioxidative stress signaling pathways. Indole-3-carbinol (I3C) and its acid condensation product, 3,3’-diindolylmethane (DIM) were examined the chemopreventive effect and the molecular mechanism, particularly the anti-oxidative stress pathway regulated by Nrf2, in transgenic adenocarcinoma of mouse prostate (TRAMP) mice and TRAMP C1 cells. I3C and DIM significantly suppressed the incidence of palpable tumor (p<0.05) and reduced the genitourinary weight (p<0.05) and induced Nrf2 and related genes expression in TRAMP mice. DIM can also epigenetically modify the CpG methylation status of Nrf2 in vivo and in vitro, and enhanced expression of Nrf2 and Nrf2-mediated genes. Using dietary phytochemicals to modulate the genomic as well as epigenomic is thought to be plausible in cancer chemoprevention in the future.