title: Dietary flavonoid genistein induces Nrf2 and phase II detoxification gene expression via ERKs and PKC pathways and protects against oxidative stress in Caco-2 cells.
abstract: METHODS
  Flavonoids have well-known antioxidant, anti-inflammatory, and anti-cancer activities. Isoflavone genistein is considered a potent antioxidant agent against oxidative stress. Although several mechanisms have been proposed, a clear antioxidant mechanism of genistein is still remained to be answered.
  
  
  RESULTS
  In this study, we focused on the concerted effects on expression of Nrf2 and phase II enzyme pathway components. Transient transfection assays, RT-PCR and immunoblot analysis were performed to study its molecular mechanisms of action. In Caco-2 cells, treatment with genistein markedly attenuated H(2)O(2) -induced peroxide formation; this amelioration was reversed by buthionine sulfoximine(GCLC inhibitor) and zinc protoporphyrin(HO-1 inhibitor). Genistein increased HO-1 and GCLC mRNA and protein expression. Genistein treatment activated the ERK1/2 and PKC signaling pathway; therefore increased Nrf2 mRNA and protein expression. The roles of the ERK1/2 and PKC signaling pathway were determined using PD98059 (ERK1/2 inhibitor) and GF109203X (PKC inhibitor) and RNA interference directed against Nrf2. Both inhibitors and siNrf2 abolished genistein-induced HO-1 and GCLC protein expression. These results suggest the involvement of ERK1/2, PKC, and Nrf2 in inducing HO-1 and GCLC by genistein.
  
  
  CONCLUSIONS
  Our studies show that genistein up-regulated HO-1 and GCLC expression through the EKR1/2 and PKC /Nrf2 pathways during oxidative stress.
authors.affiliation: Department of Pharmacology, Dalian Medical University, Dalian, P R China.
authors.forename: Xiaohan
authors.initials: X
authors.lastname: Zhai
authors.forename: Musen
authors.initials: M
authors.lastname: Lin
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Hu
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Xu
authors.forename: Yubing
authors.initials: Y
authors.lastname: Li
authors.forename: Kexin
authors.initials: K
authors.lastname: Liu
authors.forename: Xiaochi
authors.initials: X
authors.lastname: Ma
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Tian
authors.forename: Jihong
authors.initials: J
authors.lastname: Yao
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D019328:Buthionine Sulfoximine / Q000009:adverse effects; D018938:Caco-2 Cells; D005419:Flavonoids / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D019833:Genistein / Q000494:pharmacology*; D005721:Glutamate-Cysteine Ligase / Q000037:antagonists & inhibitors / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D050217:Metabolic Detoxication, Phase II / Q000502:physiology*; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D011524:Protoporphyrins / Q000009:adverse effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D011524:Protoporphyrins; D012333:RNA, Messenger; C017803:zinc protoporphyrin; D019328:Buthionine Sulfoximine; D006861:Hydrogen Peroxide; D019833:Genistein; D051547:Heme Oxygenase-1; D011493:Protein Kinase C; D005721:Glutamate-Cysteine Ligase; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one