The G protein-coupled estrogen receptor (GPER, GPR30) represents a promising target for the treatment of estrogen receptor α and β negative breast cancers. Previously reported agonists of GPER have shown that activation of GPER inhibits breast cancer cell proliferation. We report herein a new GPER agonist scaffold based upon in silico pharmacophore screening. Three of these compounds were found to increase cAMP at similar levels as the known GPER-selective agonist G-1. Compound was found to be selective for GPER (over estrogen receptor α and β) and inhibit breast cancer cell proliferation at levels consistent with G-1. Docking studies go on to suggest that both 5 and G-1 bind within the same binding pocket in GPER and point to possible key residues that are important in GPER activation.

The G protein‐coupled estrogen receptor (GPER) has been implicated in the neuroprotective effects of 17β‐estradiol and selective GPER agonist, G‐1. Currently, G‐1 remains the standard for GPER agonists, necessitating the design and identification of novel candidates. Previously, our group synthesized and biologically evaluated a series of GPER antagonists. Modification of an aromatic moiety on the scaffold altered the pharmacological profile from antagonists to agonists. Using a fluorescence‐based binding assay for the classical estrogen receptors, ERa and ERb, we discovered off‐target binding. Due to the similarity in functionalization to estradiol, we hypothesized that the hydrogen bonding abilities of the initial candidate were responsible for the observed off‐target binding. To mitigate off‐target binding, modifications were made to reduce the hydrogen bonding ability. For each resulting candidate, the EC50 value was determined through in vitro biochemical screening. From these studies, we identified a lead compound that exhibited an EC50 value below that of our experimentally determined EC50 value of G‐1. Using E18 rat embryonic hippocampal neurons, the lead compound was shown to increase synaptogenesis. These results suggest that the identified lead compound for GPER may be a potential candidate for neurodegenerative diseases.Support or Funding InformationSaint Louis UniversityThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The prevalence of gallstone disease is a major public health issue globally, and due to complex etiology of gallstones, there are a limited number of pharmaceuticals available. While the G protein‐coupled estrogen receptor (GPR30/GPER) has been shown to induce gallstone formation, little is known about its chemical biology and pharmacology. Building upon previous computational modeling of GPER, a novel series of antagonists were designed and synthesized. These novel compounds were assessed for their therapeutic value via calcium mobilization, cyclic AMP, and estrogen receptor a and β binding assays. From this series of compounds, one compound, SG‐1, exhibited superior antagonism and selectivity for GPER. The potential therapeutic value of SG‐1 was further validated in an in vivo mouse model of gallstone formation. Data revealed that SG‐1 treatment results in a dose‐dependent reduction in gallstone prevalence in estrogen‐treated ovariectomized mice.Support or Funding InformationSupported by startup funds from Saint Louis University (C.A.) and this work was supported in part by research grants DK73917 and DK101793 (to D.W.).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

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