Aims: 

We previously reported that dietary isoflavones mediate vascular relaxation via rapid activation of endothelial nitric oxide synthase (eNOS) (Joy et al., 2006) and hypothesized that isoflavone-stimulated production of reactive oxygen species (ROS) may activate induction of antioxidant defence enzymes via the Nrf2/ARE signalling pathway (Siow et al., 2007). We have now compared the effects of the estrogen receptor (ER) antagonist ICI 182,780 and selective ERb agonist diarylpripionitrile (DPN) on Nrf2/ARE mediated gene expression in human umbilical vein endothelial cells.

Methods: 

Confluent endothelial monolayers were serum-deprived (1% FCS) for 4 h and treated for 3-24 h with vehicle (0.1% DMSO), ICI 182,780 (0.01-10 mM) or DPN (100 nM). Cell lysates were extracted for SDS-PAGE analysis of heme oxygenase-1 (HO-1), NAD(P)H:quinone oxidoreductase-1 (NQO1) or glutathione peroxidase-1 (GPx-1) expression.

Results: 

ICI 182,780 evoked a concentration-dependent increase in HO-1 expression, with maximal protein expression detected after 8-12 h. ICI 182,780 had negligible effects on NQO1 or GPx-1 expression. DPN (100 nM) similarly increased HO-1 expression.

Conclusions: 

Similar to the actions of isoflavones, ER antagonists/agonist may stimulate intracellular ROS production and kinase pathways leading to Nrf2/ARE mediated gene expression.

References: Joy S et al. J. Biol. Chem. 281:27335-27345, 2006. Siow RC et al. Free Radic. Biol. Med. 42:909-925, 2007.

Supported by Heart Research UK and EU COST ACTION B35