G-1

G-1 is a potent and selective agonist of GPR30 with EC50 value of 2 nM [1].

G protein-coupled receptor 30 (GPR30) is an integral membrane protein that localizes to the endoplasmic reticulum and with high affinity for estradiol and aldosterone. GPR30 participates in multiple intracellular signaling pathways [1].

G-1 is a potent and selective GPR30 agonist. In GPR30-expressing cells, G-1 competed binding of the fluorescent estrogen with Ki value of 11 nM, while no substantial binding at concentrations up to 1 μM in ERɑ- and ERβ-expressing cells. In GPR30-expressing COS7 cells, G-1 significantly increased intracellular calcium concentrations with EC50 value of 2 nM in a dose-dependent way. In SKBr3 breast cancer cells that expressed only GPR30, G-1 activated PI3K and resulted in the nuclear accumulation of PIP3 [1].

In female Sprague–Dawley rats with bilateral ovariectomy (OVX), ISO (85 mg/kg for 17 days) was given to make the heart failure models. G-1 (120 μg/kg for 14 days) treatment reduced cardiac fibrosis and concentration of brain natriuretic peptide and increased contraction of the heart. Also, G-1 increased the expression of β2-AR and normalized the expression of β1-AR [2].

References:
[1].  Bologa CG, Revankar CM, Young SM, et al. Virtual and biomolecular screening converge on a selective agonist for GPR30. Nat Chem Biol, 2006, 2(4): 207-212.
[2].  Kang S, Liu Y, Sun D, et al. Chronic activation of the G protein-coupled receptor 30 with agonist G-1 attenuates heart failure. PLoS One, 2012, 7(10): e48185.

Determination of sub-ng g(-)(1) levels of total inorganic arsenic and selenium in foods by hydride-generation atomic absorption spectrometry after pre-concentration.[Pubmed:27879174]

Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2017 Mar;34(3):390-403.

A new and simple ultrasonic-assisted extraction (UAE) procedure was developed for the determination of inorganic arsenic and selenium in foods by hydride-generation atomic absorption spectrometry (HG-AAS). The various analytical variables affecting complex formation and extraction efficiency were investigated and optimised. The method is based on selective complex formation of As(III) and Se(IV) in the presence of excess As(V) and Se(VI) with toluidine red in the presence of tartaric acid at pH 4.5, and then extraction of the resulting condensation products into the micellar phase of non-ionic surfactant, polyethylene glycol dodecyl ether, Brij 35. Under optimised conditions, good linear relationships were obtained in the ranges of 4-225 and 12-400 ng l(-)(1) with limits of detection of 1.1 and 3.5 ng l(-)(1) for As(III) and Se(IV), respectively. The repeatability was better than 3.9% for both analytes (n = 10, 25 ng l(-)(1)) while reproducibility ranged from 4.2% to 4.8%. The recoveries of As(III) and Se(IV) spiked at 25-100 ng l(-)(1) were in the range of 94.2-104.8%. After pre-concentration of a 5.0 ml sample, the sensitivity enhancement factors for As(III) and Se(IV) were 185 and 140, respectively. Accuracy was assessed by analysis of two standard reference materials (SRMs) and spiked recovery experiments. The method was successfully applied to the accurate and reliable determination of total As and total Se by HG-AAS after pre-reduction with a mixture of L-cysteine and tartaric acid. Finally, the method was shown to be rapid and sensitive, with good results for extraction, pre-concentration and determination of total As and Se contents (as As(III) and Se(IV)) from food samples.

G-1 Inhibits Breast Cancer Cell Growth via Targeting Colchicine-Binding Site of Tubulin to Interfere with Microtubule Assembly.[Pubmed:28258163]

Mol Cancer Ther. 2017 Jun;16(6):1080-1091.

G-protein-coupled estrogen receptor 1 (GPER1) has been reported to play a significant role in mediating the rapid estrogen actions in a wide range of normal and cancer cells. G-1 was initially developed as a selective agonist for GPER. However, the molecular mechanisms underlying the actions of G-1 are unknown, and recent studies report inconsistent effects of G-1 on the growth of breast cancer cells. By employing high-resolution laser scanning confocal microscopy and time-lapse imaging technology, as well as biochemical analyses, in the current study, we provide convincing in vitro and in vivo evidence that G-1 is able to suppress the growth of breast cancer cells independent of the expression status of GPERs and classic estrogen receptors. Interestingly, we found that triple-negative breast cancer cells (TNBC) are very sensitive to G-1 treatment. We found that G-1 arrested the cell cycle in the prophase of mitosis, leading to caspase activation and apoptosis of breast cancer cells. Our mechanistic studies indicated that G-1, similar to colchicine and 2-methoxyestradiol, binds to colchicine binding site on tubulin, inhibiting tubulin polymerization and subsequent assembly of normal mitotic spindle apparatus during breast cancer cell mitosis. Therefore, G-1 is a novel microtubule-targeting agent and could be a promising anti-microtubule drug for breast cancer treatment, especially for TNBC treatment. Mol Cancer Ther; 16(6); 1080-91. (c)2017 AACR.

Development of a single-nucleotide-polymorphism marker for specific authentication of Korean ginseng (Panax ginseng Meyer) new cultivar "G-1".[Pubmed:28123319]

J Ginseng Res. 2017 Jan;41(1):31-35.

BACKGROUND: Korean ginseng (Panax ginseng) is a well-known medicinal plant of Oriental medicine that is still in practice today. Until now, a total of 11 Korean ginseng cultivars with unique features to Korean ginseng have been developed based on the pure-line-selection method. Among them, a new cultivar namely G-1 with different agricultural traits related to yield and content of ginsenosides, was developed in 2012. METHODS: The aim of this study was to distinguish the new ginseng cultivar G-1 by identifying the unique single-nucleotide polymorphism (SNP) at its 45S ribosomal DNA and Panax quinquefolius region than other Korean ginseng cultivars using multiplex amplification-refractory mutation system-polymerase chain reaction (ARMS-PCR). RESULTS: A SNP at position of 45S ribosomal DNA region between G-1, P. quinquefolius, and the other Korean ginseng cultivars was identified. By designing modified allele-specific primers based on this site, we could specifically identified G-1 and P. quinquefolius via multiplex PCR. The unique primer for the SNP yielded an amplicon of size 449 bp in G-1 cultivar and P. quinquefolius. This study presents an effective method for the genetic identification of the G-1 cultivar and P. quinquefolius. CONCLUSION: The results from our study shows that this SNP-based approach to identify the G-1 cultivar will be a good way to distinguish accurately the G-1 cultivar and P. quinquefolius from other Korean ginseng cultivars using a SNP at 45S ribosomal DNA region.

Synthesis, DNA binding affinity and anticancer activity of novel 4H-benzo[g][1,2,3]triazolo[5,1-c][1,4]oxazocines.[Pubmed:27714202]

Org Biomol Chem. 2016 Oct 4;14(39):9294-9305.

A new class of tricyclic heterocycles 4H-benzo[g][1,2,3]triazolo[5,1-c][1,4]oxazocines was synthesized through a Knoevenagel condensation/azide-alkyne cycloaddition reaction cascade in one-pot operation. These eight membered ring containing heterocycles exhibited moderately high anticancer activity against four cancer cell lines; human cervix cancer cell line (HeLa), human prostate cancer cell line (DU145), human breast cancer cell line (MCF-7) and human breast adenocarcinoma epithelial cell line (MDA-MB-231). Our results indicate that these compounds have a weak cytotoxic effect on normal human mammary epithelial cell line (MCF-10A). Cell cycle and apoptosis assay indicate that they inhibit the cell cycle at the G2/M phase and induce apoptosis. Through the RED100 assay, it is evident that they have potential to inhibit pBR 322 plasmid DNA cleavage by BamH1. UV-visible, fluorescence titration and viscosity studies suggested that these compounds possess DNA binding affinity.

The G protein-coupled receptor GPR30 inhibits proliferation of estrogen receptor-positive breast cancer cells.[Pubmed:20086172]

Cancer Res. 2010 Feb 1;70(3):1184-94.

The G protein-coupled receptor GPR30 binds 17beta-estradiol (E(2)) yet differs from classic estrogen receptors (ERalpha and ERbeta). GPR30 can mediate E(2)-induced nongenomic signaling, but its role in ERalpha-positive breast cancer remains unclear. Gene expression microarray data from five cohorts comprising 1,250 breast carcinomas showed an association between increased GPR30 expression and ERalpha-positive status. We therefore examined GPR30 in estrogenic activities in ER-positive MCF-7 breast cancer cells using G-1 and diethylstilbestrol (DES), ligands that selectively activate GPR30 and ER, respectively, and small interfering RNAs. In expression studies, E(2) and DES, but not G-1, transiently downregulated both ER and GPR30, indicating that this was ER mediated. In Ca(2+) mobilization studies, GPR30, but not ERalpha, mediated E(2)-induced Ca(2+) responses because E(2), 4-hydroxytamoxifen (activates GPR30), and G-1, but not DES, elicited cytosolic Ca(2+) increases not only in MCF-7 cells but also in ER-negative SKBr3 cells. Additionally, in MCF-7 cells, GPR30 depletion blocked E(2)-induced and G-1-induced Ca(2+) mobilization, but ERalpha depletion did not. Interestingly, GPR30-coupled Ca(2+) responses were sustained and inositol triphosphate receptor mediated in ER-positive MCF-7 cells but transitory and ryanodine receptor mediated in ER-negative SKBr3 cells. Proliferation studies involving GPR30 depletion indicated that the role of GPR30 was to promote SKBr3 cell growth but reduce MCF-7 cell growth. Supporting this, G-1 profoundly inhibited MCF-7 cell growth, potentially via p53 and p21 induction. Further, flow cytometry showed that G-1 blocked MCF-7 cell cycle progression at the G(1) phase. Thus, GPR30 antagonizes growth of ERalpha-positive breast cancer and may represent a new target to combat this disease.

Beneficial role of the GPR30 agonist G-1 in an animal model of multiple sclerosis.[Pubmed:19664827]

J Neuroimmunol. 2009 Sep 29;214(1-2):67-77.

The beneficial effects of estrogens in multiple sclerosis are thought to be mediated exclusively by the classical nuclear estrogen receptors ERalpha and ERbeta. However, recently many reports revealed that estrogens are able to mediate rapid signals through a G protein-coupled receptor (GPCR), known as GPR30. In the present study, we set out to explore whether effects mediated through this receptor were anti-inflammatory and could account for some of the beneficial effects of estrogen. We demonstrate that GPR30 is expressed in both human and mouse immune cells. Furthermore a GPR30-selective agonist, G-1, previously described by us, inhibits the production of lipopolysaccharide (LPS)-induced cytokines such as TNF-alpha and IL-6 in a dose-dependent manner in human primary macrophages and in a murine macrophage cell line. These effects are likely mediated solely through the estrogen-specific receptor GPR30 since the agonist G-1 displayed an IC(50) far greater than 10 microM on the classical nuclear estrogen receptors as well as a panel of 25 other GPCRs. Finally, we show that the agonist G-1 is able to reduce the severity of disease in both active and passive EAE models of multiple sclerosis in SJL mice and that this effect is concomitant with a G-1-mediated decrease in proinflammatory cytokines, including IFN-gamma and IL-17, in immune cells harvested from these mice. The effect of G-1 appears indirect, as the GPR30 agonist did not directly influence IFN-gamma or IL-17 production by purified T cells. These data indicate that G-1 may represent a novel therapeutic agent for the treatment of chronic autoimmune, inflammatory diseases.

G protein-coupled receptor 30 (GPR30) mediates gene expression changes and growth response to 17beta-estradiol and selective GPR30 ligand G-1 in ovarian cancer cells.[Pubmed:17308128]

Cancer Res. 2007 Feb 15;67(4):1859-66.

Estrogens play a crucial role in the development of ovarian tumors; however, the signal transduction pathways involved in hormone action are still poorly defined. The orphan G protein-coupled receptor 30 (GPR30) mediates the nongenomic signaling of 17beta-estradiol (E2) in a variety of estrogen-sensitive cancer cells through activation of the epidermal growth factor receptor (EGFR) pathway. Whether estrogen receptor alpha (ERalpha) also contributes to GPR30/EGFR signaling is less understood. Here, we show that, in ERalpha-positive BG-1 ovarian cancer cells, both E2 and the GPR30-selective ligand G-1 induced c-fos expression and estrogen-responsive element (ERE)-independent activity of a c-fos reporter gene, whereas only E2 stimulated an ERE-responsive reporter gene, indicating that GPR30 signaling does not activate ERalpha-mediated transcription. Similarly, both ligands up-regulated cyclin D1, cyclin E, and cyclin A, whereas only E2 enhanced progesterone receptor expression. Moreover, both GPR30 and ERalpha expression are required for c-fos stimulation and extracellular signal-regulated kinase (ERK) activation in response to either E2 or G-1. Inhibition of the EGFR transduction pathway inhibited c-fos stimulation and ERK activation by either ligand, suggesting that in ovarian cancer cells GPR30/EGFR signaling relays on ERalpha expression. Interestingly, we show that both GPR30 and ERalpha expression along with active EGFR signaling are required for E2-stimulated and G-1-stimulated proliferation of ovarian cancer cells. Because G-1 was able to induce both c-fos expression and proliferation in the ERalpha-negative/GPR30-positive SKBR3 breast cancer cells, the requirement for ERalpha expression in GPR30/EGFR signaling may depend on the specific cellular context of different tumor types.