ABSTRACT
AIM: 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. CONCLUSION: Benzothiophene compound BC-1 activates ARE signaling via reactive metabolite formation that is independent of estrogen receptors.
Subject(s)
Antioxidant Response Elements/drug effects , Antioxidants/metabolism , Phenols/pharmacology , Selective Estrogen Receptor Modulators/pharmacology , Signal Transduction/drug effects , Thiophenes/pharmacology , Animals , Antioxidant Response Elements/genetics , Hep G2 Cells , Humans , Mice , Microsomes, Liver/drug effects , Microsomes, Liver/metabolism , Molecular Structure , NF-E2-Related Factor 2/antagonists & inhibitors , NF-E2-Related Factor 2/genetics , Phenols/chemistry , RNA, Small Interfering/genetics , RNA, Small Interfering/pharmacology , Rats , Receptors, Estrogen/agonists , Receptors, Estrogen/antagonists & inhibitors , Selective Estrogen Receptor Modulators/chemistry , Thiophenes/chemistryABSTRACT
OBJECTIVE: To investigate the impact of cigarette smoking on sperm nucleoprotein transition and its association with sperm motility in infertile males. METHODS: We examined the semen quality and sperm nucleoprotein transition of 116 non-smokers and 113 heavy smokers (aged 25 -50 years) who visited the Research Institute of Obstetrics and Gynecology for male infertility. We determined the rate of individual sperm nucleoprotein transition by aniline blue staining and analyzed the correlation of cigarette smoking with routine semen parameters and the rate of sperm nucleoprotein transition. Based on the smoking index (SI) derived from smoking frequency (no. of cigarettes/d) multiplied by smoking duration (yr), the men with SI = 0 were considered as non-smokers, and those with SI > or = 200 as heavy smokers. RESULTS: The rate of abnormal sperm nucleoprotein transition was significantly higher in the asthenozoospermic (23.5 +/- 9.4, P < 0.01) and oligoasthenozoospermic (28.2 +/- 9.2, P < 0.01) than in the normozoospermic males (19.0 +/- 9.0). Compared with the non-smokers, cigarette smoking remarkably reduced sperm nucleoprotein transition in both the men with normal sperm motility (21.9 +/- 9.8 vs 16.8 +/- 7.7, P < 0.01) and those with abnormal sperm motility (26.0 +/- 9.9 vs 22.7 +/- 8.8, P < 0.05). A weak correlation was observed between the rate of sperm nucleoprotein transition and routine semen parameters. CONCLUSION: Cigarette smoking is not significantly correlated with sperm motility but decreases sperm nucleoprotein transition in infertile males.
