Selective estrogen receptor modulator promotes weight loss in ovariectomized female rhesus monkeys (Macaca mulatta) by decreasing food intake and increasing activity.

The effect of hormone replacement therapy (HRT) on body weight in postmenopausal women is controversial, with studies reporting an increase, a decrease, and no change in body weight. To examine estrogen receptor actions on body weight, we investigated the effects of treatment with a selective estrogen receptor modulator (SERM) on body weight, food intake, and activity and metabolic rate in a nonhuman primate model. Eighteen ovariectomized female rhesus monkeys were treated with a nonsteroidal SERM (GSK232802A, 5 mg/kg po) for 3 mo. GSK232802A decreased lutenizing hormone (P < 0.0001) and follicle-stimulating hormone levels (P < 0.0001), consistent with the estrogenic action of the compound. GSK232802A treatment produced a small but sustained weight loss (4.6 ± 1.0%, P < 0.0001) and reduced adiposity (P < 0.0001), which was due at least in part to a suppression of food intake (3.6 ± 3.7%, P < 0.0001). Physical activity increased during the 3rd mo of treatment (P = 0.04). Baseline activity level and the change in activity due to treatment were correlated, with the most sedentary individuals exhibiting increased physical activity during the 1st mo of treatment (P = 0.02). Metabolic rate did not change (P = 0.58). These results indicate that GSK232802A treatment reduces body weight and adiposity in ovariectomized nonhuman primates by suppressing food intake and increasing activity, particularly in the most sedentary individuals. These findings suggest that SERM treatment may counteract weight gain in postmenopausal women.

Synthesis of 3-alkyl naphthalenes as novel estrogen receptor ligands.

A series of estrogen receptor ligands based on a 3-alkyl naphthalene scaffold was synthesized using an intramolecular enolate-alkyne cycloaromatization as the key step. Several of these compounds bearing a C6-OH group were shown to be high affinity ligands. All compounds had similar ERalpha and ERbeta binding affinity ranging from micromolar to low nanomolar.

Discovery of novel quinoline-based estrogen receptor ligands using peptide interaction profiling.

Traditional approaches to discovery of selective estrogen receptor modulators (SERMs) have relied on ER binding and cell-based estrogen response element-driven assays to identify compounds that are osteoprotective but nonproliferative in breast and uterine tissues. To discover new classes of potential SERMs, we have employed a cell-free microsphere-based binding assay to rapidly characterize ERalpha interactions with conformation-sensing cofactor or phage display peptides. Peptide profiles of constrained triarenes were compared to known proliferative and nonproliferative ER ligands to discover potent quinoline-based ligands with minimal Ishikawa cell stimulation.

Correlation between in vitro peptide binding profiles and cellular activities for estrogen receptor-modulating compounds.

Numerous biochemical and structural studies have shown that the conformation of the estrogen receptor alpha (ERalpha) can be influenced by ligand binding. In turn, the conformational state of ERalpha affects the ability of the receptor to interact with a wide variety of protein accessory factors. To globally investigate ligand-based cofactor recruitment activities of ERalpha, we have applied a flow cytometric multiplexed binding assay to determine the simultaneous binding of ERalpha to over 50 different peptides derived from both known cofactor proteins and random peptide phage display. Using over 400 ERalpha-binding compounds, we have observed that the multiplexed in vitro peptide-binding profiles are distinct for a number of compounds and that these profiles can predict the effect that ERalpha ligands have on various cellular activities. These cell-based activities include transcriptional regulation at an estrogen response element, MCF-7 cell proliferation, and Ishikawa endometrial cell stimulation. The majority of the compound-induced diversity in the peptide profiling assay is provided by the unique phage display peptides. Importantly, some of these peptides show a sequence relationship with the corepressor motif, suggesting that peptides identified via phage display might represent natural binding partners of ERalpha. These in vitro:cellular correlations may in part explain tissue-specific activities of ERalpha-modulating compounds.

A new series of estrogen receptor modulators that display selectivity for estrogen receptor beta.

A series of 1,3,5-triazine-based estrogen receptor (ER) modulators that are modestly selective for the ERbeta subtype are reported. Compound 1, which displayed modest potency and selectivity for ERbeta vs ERalpha, was identified via high-throughput screening utilizing an ERbeta SPA-based binding assay. Subsequent analogue preparation resulted in the identification of compounds such as 21 and 43 that display 25- to 30-fold selectivity for ERbeta with potencies in the 10-30 nM range. These compounds profile as full antagonists at ERbeta and weak partial agonists at ERalpha in a cell-based reporter gene assay. In addition, the X-ray crystal structure of compound 15 complexed with the ligand binding domain of ERbeta has been solved and was utilized in the design of more conformationally restrained analogues such as 31 in an attempt to increase selectivity for the ERbeta subtype.