A novel GPER antagonist protects against the formation of estrogen-induced cholesterol gallstones in female mice

Abstract

Many clinical studies and epidemiological investigations have clearly demonstrated that women are twice as likely to develop cholesterol gallstones as men, and oral contraceptives and other estrogen therapies dramatically increase that risk. Further, animal studies have revealed that estrogen promotes cholesterol gallstone formation through the estrogen receptor (ER) α, but not ERβ, pathway. More importantly, some genetic and pathophysiological studies have found that G protein-coupled estrogen receptor (GPER) 1 is a new gallstone gene, Lith18, on chromosome 5 in mice and produces additional lithogenic actions, working independently of ERα, to markedly increase cholelithogenesis in female mice. Based on computational modeling of GPER, a novel series of GPER-selective antagonists were designed, synthesized, and subsequently assessed for their therapeutic effects via calcium mobilization, cAMP, and ERα and ERβ fluorescence polarization binding assays. From this series of compounds, one new compound, 2-cyclohexyl-4-isopropyl-N-(4-methoxybenzyl)aniline (CIMBA), exhibits superior antagonism and selectivity exclusively for GPER. Furthermore, CIMBA reduces the formation of 17β-estradiol-induced gallstones in a dose-dependent manner in ovariectomized mice fed a lithogenic diet for 8 weeks. At 32 μg/day/kg CIMBA, no gallstones are found, even in ovariectomized ERα (−/−) mice treated with 6 μg/day 17β-estradiol and fed the lithogenic diet for 8 weeks. In conclusion, CIMBA treatment protects against the formation of estrogen-induced cholesterol gallstones by inhibiting the GPER signaling pathway in female mice. CIMBA may thus be a new agent for effectively treating cholesterol gallstone disease in women.­

Therapeutic Perspectives on the Modulation of G-Protein Coupled Estrogen Receptor, GPER, Function

“…Thus, GPER provides a likely mechanism by which metabolic disorder may be part of the landscape for estrogen-driven malignancies. The selective GPER antagonists, G15 delays the growth of endometrial cancer (63) and exciting new data indicates that a new GPER antagonist, CIMBA, can prevent estrogen-induced gallstones (119).…”

“…G36 inhibits E2 and G-1-dependent calcium mobilization as well as erk-1/2 activation in SKBR3 cells (IC 50 = 200 nM) and blocks the growth of transplanted estrogen-dependent type II endometrial cancer cells (63). Recently, Chris Arnatt and David Wang have collaborated to report a new GPER antagonist that protects ovariectomized ERa null mice from estrogen-induced cholesterol gallstones (119). Using a receptor-ligand interaction computational screen, a novel series of GPER-selective antagonists were generated, including one new compound, 2cyclohexyl-4-isopropyl-N-(4-methoxybenzyl) aniline (CIMBA).…”

G Protein-Coupled Estrogen Receptor, GPER1, Offers a Novel Target for the Treatment of Digestive Diseases

“…More recently, exciting evidence shows that a novel, potent GPER1-selective antagonist, CIMBA, reduces the prevalence of E2-induced gallstones in a dose-dependent manner by impeding the GPER1 signaling pathway in female wild-type mice (76). However, gallstones can be completely prevented in E2-treated ESR1 knockout mice even on the lithogenic diet (76). These results are consistent with the findings that the deletion of either Esr1 or Gper1 significantly reduces the prevalence of E2-induced gallstones but could not abolish it completely.…”

GPER and Testicular Germ Cell Cancer

“…However, G-15 exhibits a partial cross-reactivity with ERα explaining why G-36 is mainly used in the study of GPER/GPR30 ( 102 ). Other pharmacological ligands were synthetized (GPER/GPR30-L1 and GPER/GPR30-L2) ( 102 , 103 ) but they exhibit variable affinities for GPER/GPR30 and potential cross-reactivity with classical ERs, explaining why they cannot be considered as therapeutic tools at this time ( 104 ). These small molecules were used especially in vitro , as we did with seminoma cells; in our model, G-1 was able to mimic the proliferative effect of BPA while G-15 neutralized this effect and reduced cell proliferation in the presence of BPA ( 71 ).…”