Identification of novel estrogen receptor alpha antagonists.
We have identified novel estrogen receptor alpha (ERalpha) antagonists using both cell-based and computer-based virtual screening strategies. A mammalian two-hybrid screen was used to select compounds that disrupt the interaction between the ERalpha ligand binding domain (LBD) and the coactivator SRC-3. A virtual screen was designed to select compounds that fit onto the LxxLL peptide-binding surface of the receptor, based on the X-ray crystal structure of the ERalpha LBD complexed with a LxxLL peptide. All selected compounds effectively inhibited 17-beta-estradiol induced coactivator recruitment with potency ranging from nano-molar to micromolar. However, in contrast to classical ER antagonists, these novel inhibitors poorly displace estradiol in the ER-ligand competition assay. Nuclear magnetic resonance (NMR) suggested direct binding of these compounds to the receptors pre-complexed with estradiol and further demonstrated that no estradiol displacement occurred. Partial proteolytic enzyme digestion revealed that, when compared with 17-beta-estradiol- and 4 hydroxy-tamoxifen (4-OHT) bound receptors, at least one of these compounds might induce a unique receptor conformation. These small molecules may represent new classes of ER antagonists, and may have the potential to provide an alternative for the current anti-estrogen therapy.
Shao
Dalei
D
Women's Health and Bone, Wyeth Research, 500 Arcola Road, RN2294, Collegeville, PA 19426, USA. shaod1@wyeth.com
Berrodin
Thomas J
TJ
Manas
Eric
E
Hauze
Diane
D
Powers
Robert
R
Bapat
Ashok
A
Gonder
Daniel
D
Winneker
Richard C
RC
Frail
Donald E
DE
D000123:Acetyltransferases; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D004353:Drug Evaluation, Preclinical / Q000379:methods; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology*; D047628:Estrogen Receptor alpha; D000077267:Fulvestrant; D051548:Histone Acetyltransferases; D006801:Humans; D006915:Hydroxytestosterones / Q000494:pharmacology; D008024:Ligands; D056921:Nuclear Receptor Coactivator 3; D015513:Oncogene Proteins; D011485:Protein Binding / Q000187:drug effects; D011487:Protein Conformation / Q000187:drug effects; D011960:Receptors, Estrogen / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism
D000970:Antineoplastic Agents; D004965:Estrogen Antagonists; D047628:Estrogen Receptor alpha; D006915:Hydroxytestosterones; D008024:Ligands; D015513:Oncogene Proteins; D011960:Receptors, Estrogen; D015534:Trans-Activators; C032278:4,17 beta-dihydroxy-4-androstene-3-one; D000077267:Fulvestrant; D004958:Estradiol; D000123:Acetyltransferases; D051548:Histone Acetyltransferases; C538866:NCOA3 protein, human; D056921:Nuclear Receptor Coactivator 3