Estrogen receptor (ER) beta is predicted to play an important role in the prevention of breast cancer development and progression. We have previously shown that ER beta suppresses hypoxia inducible factor (HIF)1-mediated transcription through aryl hydrocarbon receptor nuclear translocator (ARNT) degradation via ubiquitination processes. In this study, we attempted to examine the effect of ER beta specific ligand on HIF-1 inhibition in ER beta positive PC3 cells and ER beta transfected MCF-7 cells. ER beta specific agonist diarylpropionitrile (DPN) stimulated estrogen response element (ERE)-luciferase activity in a similar fashion to estradiol in PC3 cells. We observed that DPN down-regulates the ARNT protein levels leading to an attenuation of hypoxia-induced hypoxia response element (HRE)-driven luciferase reporter gene activation in PC3 cells. Treatment of DPN reduced vascular endothelial growth factor (VEGF) expression and co-treatment with ER beta specific antagonist PHTPP abrogated the effect in PC3 cells. We then examined the effect of DPN in ER beta transfected MCF-7 cells. HIF-1 transcriptional activity repression by ER beta was not further reduced by DPN, as examined by HRE-driven luciferase assays. Expression of ER beta significantly decreased VEGF secretion and ARNT expression under hypoxic conditions. However, DPN did not additionally affect this suppression in MCF-7 cells transfected with ER beta. This result shows that unliganded ER beta is sufficient to inhibit HIF-1 in systems of overexpression. (C) 2014 Elsevier Inc. All rights reserved.