title: Selective estrogen receptor modulator BC-1 activates antioxidant signaling pathway in vitro via formation of reactive metabolites.
abstract: OBJECTIVE
  Benzothiophene compounds are selective estrogen receptor modulators (SERMs), which are recently found to activate antioxidant signaling. In this study the molecular mechanisms of antioxidant signaling activation by benzothiophene compound BC-1 were investigated.
  
  
  METHODS
  HepG2 cells were stably transfected with antioxidant response element (ARE)-luciferase reporter (HepG2-ARE cells). The expression of nuclear factor erythroid 2-related factor 2 (Nrf2) in HepG2-ARE cells was suppressed using siRNA. The metabolites of BC-1 in rat liver microsome incubation were analyzed using LC-UV and LC-MS.
  
  
  RESULTS
  Addition of BC-1 (5 μmol/L) in HepG2-ARE cells resulted in a 17-fold increase of ARE-luciferase activity. Pretreatment with the estrogen receptor agonist E2 (5 μmol/L) or antagonist ICI 182,780 (5 μmol/L) did not affect BC-1-induced ARE-luciferase activity. However, transfection of the cells with anti-Nrf2 siRNA suppressed this effect by 79%. Addition of BC-1 in rat microsome incubation resulted in formation of di-quinone methides and o-quinones, followed by formation of GSH conjugates. BC-1 analogues with hydrogen (BC-2) or fluorine (BC-3) at the 4' position did not form the di-quinone methides. Both BC-2 and BC-3 showed comparable estrogenic activity with BC-1, but did not induce ARE-luciferase activity in HepG2-ARE cells.
  
  
  CONCLUSIONS
  Benzothiophene compound BC-1 activates ARE signaling via reactive metabolite formation that is independent of estrogen receptors.
authors: Key Laboratory of Reproduction and Genetics of Guangdong Higher Education Institute, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou 510150, China. yubolan@gmail.com
authors: Bo-lan
authors: BL
authors: Yu
authors: Zi-xin
authors: ZX
authors: Mai
authors: Xu-xiang
authors: XX
authors: Liu
authors: Zhao-feng
authors: ZF
authors: Huang
mesh_terms: D000818:Animals; D061745:Antioxidant Response Elements / Q000187:drug effects* / Q000235:genetics; D000975:Antioxidants / Q000378:metabolism*; D056945:Hep G2 Cells; D006801:Humans; D051379:Mice; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D015394:Molecular Structure; D051267:NF-E2-Related Factor 2 / Q000037:antagonists & inhibitors / Q000235:genetics; D010636:Phenols / Q000737:chemistry / Q000494:pharmacology*; D034741:RNA, Small Interfering / Q000235:genetics / Q000494:pharmacology; D051381:Rats; D011960:Receptors, Estrogen / Q000819:agonists / Q000037:antagonists & inhibitors; D020845:Selective Estrogen Receptor Modulators / Q000737:chemistry / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects*; D013876:Thiophenes / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; C585238:BC-1 benzothiophene compound; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D010636:Phenols; D034741:RNA, Small Interfering; D011960:Receptors, Estrogen; D020845:Selective Estrogen Receptor Modulators; D013876:Thiophenes