Effects of Inhibiting the Proteasomal Degradation of Estrogen Receptor α on Estrogen Receptor α Activation under Hypoxic Conditions

Abstract

Hypoxia, which is intimately associated with the biology of breast carcinomas, modulates the level of estrogen receptor (ER) α expression and transactivation. We investigated the effect of blocking ER degradation on ERα-mediated transactivation under hypoxic conditions using the proteasome inhibitor MG132. Pretreatment with MG132 blocked hypoxia-induced degradation of ERα protein. Our data imply that ERα proteasomal inhibition is linked to receptor transactivation under hypoxia.