Nrf2: a potential molecular target for cancer chemoprevention by natural compounds.
One of the most prominent strategies of cancer chemoprevention might be protecting cells or tissues against various carcinogens and carcinogenic metabolites derived from exogenous or endogenous sources. This protection could be achieved through the induction of phase 2 detoxifying enzymes and antioxidant enzymes such as glutathione S-transferase, NAD(P)H quinone oxidoreductase 1, and heme oxygenase-1, a process that is mediated mainly by the antioxidant response elements (ARE) within the promoter regions of these genes. Nuclear factor-erythroid 2-related factor 2 (Nrf2), a member of the Cap 'n' collar (CNC) family of basic region-leucine zipper transcription factors, plays a key role in ARE-mediated gene expression. Under normal condition, Nrf2 is sequestered in the cytoplasm by an actin-binding protein, Kelch-like ECH associating protein 1 (Keap1), and upon exposure of cells to inducers such as oxidative stress and certain chemopreventive agents, Nrf2 dissociates from Keap1, translocates to the nucleus, binds to AREs, and transactivates phase 2 detoxifying and antioxidant genes. Several upstream signaling pathways including mitogen-activated protein kinases, protein kinase C, phosphatidylinositol 3-kinase, and transmembrane kinase are implicated in the regulation of Nrf2/ARE activity. Furthermore, many natural chemopreventive agents are known to induce Nrf2/ARE-dependent gene expression, also in part by regulating the turnover of the Nrf2 protein itself. This review discusses our current understanding of the Nrf2/ARE pathway as a potential molecular target for cancer chemoprevention, as well as the feasibility of screening natural compounds for activation of this pathway and as potential cancer preventive agents for human use.
Food Science Institute, School of Food & Life Science, College of Biomedical Science & Engineering, Inje University, South Korea.
Woo-Sik
WS
Jeong
Mira
M
Jun
Ah-Ng Tony
AN
Kong
D000818:Animals; D016588:Anticarcinogenic Agents / Q000627:therapeutic use; D000975:Antioxidants / Q000627:therapeutic use*; D001688:Biological Products / Q000627:therapeutic use*; D005786:Gene Expression Regulation; D006801:Humans; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D009369:Neoplasms / Q000517:prevention & control*; D021381:Protein Transport
D016588:Anticarcinogenic Agents; D000975:Antioxidants; D001688:Biological Products; D051267:NF-E2-Related Factor 2