Role of Nrf2 Cross-Talk in Cancer Chemoprevention

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DESCRIPTION (provided by applicant): Activation of the Keap1-Nrf2 signaling pathway is an adaptive response to environmental and endogenous stresses and serves to render animals resistant to chemical carcinogenesis and other forms of toxicity, whereas disruption of the pathway exacerbates these outcomes. This pathway, which can be activated by sulfhydryl reactive, small-molecule pharmacologic and food-based agents used in chemoprevention, regulates the inducible expression of an extended battery of cytoprotective genes, often by direct binding of the transcription factor Nrf2 to antioxidant response elements in the promoter regions of target genes. However, our recent work indicates that some of the protective effects may be mediated indirectly through cross-talk with additional pathways affecting cell survival and other aspects of cell fate. These interactions provide a multi-tiered, integrated response to chemical stresses through: (i) prevention of macromolecular damage through induction of antioxidative, anti-inflammatory and carcinogen detoxication genes; (ii) induction of macromolecular damage recognition, repair/removal systems; and (iii) activation of tissue repair/regeneration pathways. In this project we seek to use molecular, genetic and chemical approaches to test the hypothesis that chemoprotection mediated by Nrf2 reflects both activation of its direct target genes but importantly cross- talk with other adaptive response signaling networks affecting cell fate, such as Notch1. The overall goals of the proposed studies are two-fold: to assess the underlying mechanisms and consequences of pathway cross-talk and to assess the functional significance and possible untoward effects of chronic induction of the Nrf2 response in order to facilitate the identification and utilization of safe, efficacious chemopreventive agents.