Differential response of estrogen receptor subtypes to 1,3-diarylindene and 2,3-diarylindene ligands

Estrogen receptors (ERs) control transcription of genes important for normal human development and reproduction. The signaling networks are complex, and there is a need for a molecular level understanding of the roles of receptor subtypes ER alpha and ER beta in normal physiology and as therapeutic targets. We synthesized two series of ER ligands, based on a common indene scaffold, in an attempt to develop compounds that can selectively modulate ER-mediated transcription. The 3-ethyl-1,2-diarylindenes, utilizing an amide linker for the 1-aryl extension, bind weakly to the ERs. The 2,3-diarylindenes bind with high affinity to the ER subtypes and demonstrate a range of different biological activities, both in transcriptional reporter gene assays and inhibition of estradiol-stimulated proliferation of MCF-7 cells. Several ligands differentiate between ER alpha and ER beta subtypes at an estrogen response element (ERE), displaying various levels of partial to full agonist activity at ER alpha, while antagonizing estradiol action at ER beta.