Identification of a GPER/GPR30 antagonist with improved estrogen receptor counterselectivity

GPER/GPR30 is a seven-transmembrane G protein-coupled estrogen receptor that regulates many aspects of mammalian biology and physiology. We have previously described both a GPER-selective agonist G-1 and antagonist G15 based on a tetrahydro-3H-cyclopenta[c]quinoline scaffold. The antagonist lacks an ethanone moiety that likely forms important hydrogen bonds involved in receptor activation. Computational docking studies suggested that the lack of the ethanone substituent in G15 could minimize key steric conflicts, present in G-1, that limit binding within the ERα ligand binding pocket. In this report, we identify low-affinity cross-reactivity of the GPER antagonist G15 to the classical estrogen receptor ERα. To generate an antagonist with enhanced selectivity, we therefore synthesized an isosteric G-1 derivative, G36, containing an isopropyl moiety in place of the ethanone moiety. We demonstrate that G36 shows decreased binding and activation of ERα, while maintaining its antagonist profile towards GPER. G36 selectively inhibits estrogen-mediated activation of PI3K by GPER but not ERα. It also inhibits estrogen- and G-1-mediated calcium mobilization as well as ERK1/2 activation, with no effect on EGF-mediated ERK1/2 activation. Similar to G15, G36 inhibits estrogen- and G-1-stimulated proliferation of uterine epithelial cells in vivo. The identification of G36 as a GPER antagonist with improved ER counterselectivity represents a significant step towards the development of new highly selective therapeutics for cancer and other diseases.     

MicroRNA expression in ovarian carcinoma and its correlation with clinicopathological features

ABSTRACT: BACKGROUND: MicroRNA (miRNA) expression is known to be deregulated in ovarian carcinomas. However, limited data is available about the miRNA expression pattern for the benign or borderline ovarian tumors as well as differential miRNA expression pattern associated with histological types, grades or clinical stages in ovarian carcinomas. We defined patterns of microRNA expression in tissues from normal, benign, borderline, and malignant ovarian tumors and explored the relationship between frequently deregulated miRNAs and clinicopathologic findings, response to therapy, survival, and association with Her-2/neu status in ovarian carcinomas. METHODS: We measured the expression of nine miRNAs (miR-181d, miR-30a-3p, miR-30c, miR-30d, miR-30e-3p, miR-368, miR-370, miR-493-5p, miR-532-5p) in 171 formalin-fixed, paraffin-embedded ovarian tissue blocks as well as six normal human ovarian surface epithelial (HOSE) cell lines using Taqman-based real-time PCR assays. Her-2/neu overexpression was assessed in ovarian carcinomas (n = 109 cases) by immunohistochemistry analysis. RESULTS: Expression of four miRNAs (miR-30c, miR-30d, miR-30e-3p, miR-370) was significantly different between carcinomas and benign ovarian tissues as well as between carcinoma and borderline tissues. An additional three miRNAs (miR-181d, miR-30a-3p, miR-532-5p) were significantly different between borderline and carcinoma tissues. Expression of miR-532-5p was significantly lower in borderline than in benign tissues. Among ovarian carcinomas, expression of four miRNAs (miR-30a-3p, miR-30c, miR-30d, miR-30e-3p) was lowest in mucinous and highest in clear cell samples. Expression of miR-30a-3p was higher in well-differentiated compared to poorly differentiated tumors (P = 0.02), and expression of miR-370 was higher in stage I/II compared to stage III/IV samples (P = 0.03). In multivariate analyses, higher expression of miR-181d, miR-30c, miR-30d, and miR-30e-3p was associated with significantly better disease-free or overall survival. Finally, lower expression of miR-30c, miR-30d, miR-30e-3p and miR-532-5p was significantly associated with overexpression of Her-2/neu. CONCLUSIONS: Aberrant expression of miRNAs is common in ovarian tumor suggesting involvement of miRNA in ovarian tumorigenesis. They are associated with histology, clinical stage, survival and oncogene expression in ovarian carcinoma.     

VEGF、MMP-2与MMP-9在卵巢癌组织中的表达及其临床意义

目的:探讨VEGF、MMP-2和MMP-9在卵巢癌组织中的表达及其与卵巢癌发生发展的关系.方法:采用免疫组织化学法检测VEGF、MMP-2和MMP-9在正常卵巢组织、卵巢癌组织中的表达,并对三者的相关性进行分析.结果:卵巢癌组织中VEGF、MMP-2和MMP-9蛋白的表达阳性率显著高于正常卵巢组织(P<0.05),且在卵巢癌Ⅲ～Ⅳ期患者标本中阳性率高于Ⅰ～Ⅱ期(P<0.05);VEGF、MMP-2和MMP-9蛋白阳性表达率与卵巢癌临床分期和淋巴结转移有关(P<0.05).结论:正常卵巢组织和卵巢癌组织中VEGF、MMP-2和MMP-9蛋白含量的变化一致;VEGF、MMP-2和MMP-9均参与了卵巢癌的发生发展过程,三者间可能有协同作用.     

Association of the membrane estrogen receptor, GPR30, with breast tumor metastasis and transactivation of the epidermal growth factor receptor

The epidermal growth factor receptor (EGFR) family of receptor tyrosine kinases function as a common signaling conduit for membrane receptors that lack intrinsic enzymatic activity, such as G-protein coupled receptors and integrins. GPR30, an orphan member of the seven transmembrane receptor (7TMR) superfamily has been linked to specific estrogen binding, rapid estrogen-mediated activation of adenylyl cyclase and the release of membrane-tethered proHB-EGF. More recently, GPR30 expression in primary breast adenocarcinoma has been associated with pathological parameters commonly used to assess breast cancer progression, including the development of extramammary metastases. This newly appreciated mechanism of cross communication between estrogen and EGF is consistent with the observation that 7TMR-mediated transactivation of the EGFR is a recurrent signaling paradigm and may explain prior data reporting the EGF-like effects of estrogen. The molecular details surrounding GPR30-mediated release of proHB-EGF, the involvement of integrin beta1 as a signaling intermediary in estrogen-dependent EGFR action, and the possible implications of these data for breast cancer progression are discussed herein.     

High Estrogen Level Modifies Postoperative Hyperalgesia via GPR30 and MMP-9 in Dorsal Root Ganglia Neurons

Neurochemical Research - The cycling of sex hormones is one of the factors affecting pain in females, and the mechanisms are not fully understood. G-protein coupled estrogen receptor 30 (GPR30) is...     

The activation of G protein-coupled receptor 30 (GPR30) inhibits proliferation of estrogen receptor-negative breast cancer cells in vitro and in vivo

There is an urgent clinical need for safe and effective treatment agents and therapy targets for estrogen receptor negative (ER−) breast cancer. G protein-coupled receptor 30 (GPR30), which mediates non-genomic signaling of estrogen to regulate cell growth, is highly expressed in ER− breast cancer cells. We here showed that activation of GPR30 by the receptor-specific agonist G-1 inhibited the growth of ER− breast cancer cells in vitro. Treatment of ER− breast cancer cells with G-1 resulted in G2/M-phase arrest, downregulation of G2-checkpoint regulator cyclin B, and induction of mitochondrial-related apoptosis. The G-1 treatment increased expression of p53 and its phosphorylation levels at Serine 15, promoted its nuclear translocation, and inhibited its ubiquitylation, which mediated the growth arrest effects on cell proliferation. Further, the G-1 induced sustained activation and nuclear translocation of ERK1/2, which was mediated by GPR30/epidermal growth factor receptor (EGFR) signals, also mediated its inhibition effects of G-1. With extensive use of siRNA-knockdown experiments and inhibitors, we found that upregulation of p21 by the cross-talk of GPR30/EGFR and p53 was also involved in G-1-induced cell growth arrest. In vivo experiments showed that G-1 treatment significantly suppressed the growth of SkBr3 xenograft tumors and increased the survival rate, associated with proliferation suppression and upregulation of p53, p21 while downregulation of cyclin B. The discovery of multiple signal pathways mediated the suppression effects of G-1 makes it a promising candidate drug and lays the foundation for future development of GPR30-based therapies for ER− breast cancer treatment.Breast cancer is the most frequently diagnosed cancer and the leading cause of cancer death in females worldwide.¹ Clinically, breast cancer is generally classified into estrogen receptor α positive (ER+) or ER-negative (ER−) subtypes.² ER− tumors are often intrinsically more aggressive and of higher grade than ER+ tumors.³ Since lack of the effectiveness of ER-targeted endocrine treatments (tamoxifen and aromatase inhibitors), patients with ER− breast cancer have significantly worse prognosis and greater 5-year recurrence rate than that of ER+ breast cancer.⁴ Considering that ER− breast cancer constitutes around 30% of all breast cancers,⁵ there is an urgent need to explore new targeted approaches for its treatment.A seven-transmembrane receptor G protein-coupled receptor 30 (GPR30), which is structurally unrelated to nuclear ER, has been recently shown to mediate rapid non-genomic signals of estrogens. The activation of GPR30 can stimulate adenylyl cyclase, transactivate epidermal growth factor receptors (EGFRs), induce mobilization of intracellular calcium (Ca²⁺) stores, and activate mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K) signaling pathways.^6,7 Previous studies revealed that GPR30 can modulate growth of hormonally responsive cancers such as endometrial,⁸ ovarian,⁹ and breast cancer.¹⁰ Therefore, GPR30 likely has an important role in modulating estrogen responsiveness and development and/or progression of ER− breast cancer. Studies revealed that activation of GPR30 can induce the expression of genes and activate pathways that facilitate cell proliferation of endometrial,^11,12 breast,¹³ and ovarian cancer.¹⁴ On the contrary, numerous studies demonstrated that activation of GPR30 by its specific agonist G-1 results in cell-cycle arrest and proliferation inhibition of ERα-positive breast cancer,¹⁰ endothelial cells,¹⁵ prostate,¹⁶ and ovarian⁹ cancer cells. So it requires further investigation on the function of activating GPR30 and the effect of G-1 on the cancer cells.GPR30 has been reported to be expressed in ER− breast cancer cells and suggested to be an excellent new therapeutic target for the treatment of ER− breast cancer.¹⁷ Confusedly, the only two published papers reported contradictory results: Girgert et al.¹⁸ stated that activation of GPR30 promotes growth of ER− breast cancer cells, while Weissenborn et al.¹⁹ revealed that GPR30 functions as a tumor suppressor of ER− breast cancer cells. Therefore, there is an urgent need to illustrate the effects of GPR30 on the proliferation of ER− breast cancer and its downstream signal mechanisms. In the present study, we demonstrated that activation of GPR30 by G-1 inhibits the proliferation of ER− breast cancer cells both in vitro and in vivo.     

Potential role of estrogen receptor Beta as a tumor suppressor of epithelial ovarian cancer

Ovarian cancer is the gynecological cancer exhibiting the highest morbidity and improvement of treatments is still required. Previous studies have shown that Estrogen-receptor beta (ERβ) levels decreased along with ovarian carcinogenesis. Here, we present evidence that reintroduction of ERβ in BG-1 epithelial ovarian cancer cells, which express ERα, leads in vitro to a decrease of basal and estradiol-promoted cell proliferation. ERβ reduced the frequency of cells in S phase and increased the one of cells in G2/M phase. At the molecular level, we found that ERβ downregulated total retinoblastoma (Rb), phosphorylated Rb and phospho-AKT cellular content as well as cyclins D1 and A2. In addition, ERβ had a direct effect on ERα, by strongly inhibiting its expression and activity, which could explain part of the anti-proliferative action of ERβ. By developing a novel preclinical model of ovarian cancer based on a luminescent orthotopic xenograft in athymic Nude mice, we further revealed that ERβ expression reduces tumor growth and the presence of tumor cells in sites of metastasis, hence resulting in improved survival of mice. Altogether, these findings unveil a potential tumor-suppressor role of ERβ in ovarian carcinogenesis, which could be of potential clinical relevance for the selection of the most appropriate treatment for patients.     

The novel estrogen receptor GPER regulates the migration and invasion of ovarian cancer cells

G protein-coupled estrogen receptor (GPER) was identified as a new member of the estrogen receptor family in recent years. It has become apparent that GPER mediates the non-genomic signaling of 17β-estradiol (E₂) in a variety of estrogen-related cancers. Our previous study has found that GPER was overexpressed in human epithelial ovarian cancer and was positively correlated with the expression of matrix metalloproteinase 9 (MMP-9), which suggested GPER might promote the metastasis of ovarian cancer. However, the mechanisms underlying GPER-dependent metastasis of ovarian cancer are still not clear. In the present study, estrogen receptor α (ERα)-negative/GPER-positive OVCAR5 ovarian cancer cell line was used to investigate the role of GPER in the migration and invasion of ovarian cancer. Wound healing assay and transwell matrigel invasion assay were performed to determine the potentials of cell migration and invasion, respectively. The production and activity of MMP-9 in OVCAR5 cells were examined by Western blot and gelatin zymography analysis. The results showed that E₂ and selective GPER agonist G-1 increased cell motility and invasiveness, and upregulated the production and proteolytic activity of MMP-9 in OVCAR5 cells. Small interfering RNA (siRNA) targeting GPER and G protein inhibitor pertussin toxin (PTX) inhibited the migration and invasion of OVCAR5 cells, and also reduced the expression and activity of MMP-9. Our data suggested that GPER promoted the migration and invasion of ovarian cancer cells by increasing the expression and activity of MMP-9. GPER might play an important role in the progression of ovarian cancer.     

GPR30, the non-classical membrane G protein related estrogen receptor, is overexpressed in human seminoma and promotes seminoma cell proliferation

Background

Testicular germ cell tumours are the most frequent cancer of young men with an increasing incidence all over the world. Pathogenesis and reasons of this increase remain unknown but epidemiological and clinical data have suggested that fetal exposure to environmental endocrine disruptors (EEDs) with estrogenic effects, could participate to testicular germ cell carcinogenesis. However, these EEDs (like bisphenol A) are often weak ligands for classical nuclear estrogen receptors. Several research groups recently showed that the non classical membrane G-protein coupled estrogen receptor (GPER/GPR30) mediates the effects of estrogens and several xenoestrogens through rapid non genomic activation of signal transduction pathways in various human estrogen dependent cancer cells (breast, ovary, endometrium). The aim of this study was to demonstrate that GPER was overexpressed in testicular tumours and was able to trigger JKT-1 seminoma cell proliferation.

Results

We report here for the first time a complete morphological and functional characterization of GPER in normal and malignant human testicular germ cells. In normal adult human testes, GPER was expressed by somatic (Sertoli cells) and germ cells (spermatogonia and spermatocytes). GPER was exclusively overexpressed in seminomas, the most frequent testicular germ cell cancer, localized at the cell membrane and triggered a proliferative effect on JKT-1 cells in vitro, which was completely abolished by G15 (a GPER selective antagonist) and by siRNA invalidation.

Conclusion

These results demonstrate that GPER is expressed by human normal adult testicular germ cells, specifically overexpressed in seminoma tumours and able to trigger seminoma cell proliferation in vitro. It should therefore be considered rather than classical ERs when xeno-estrogens or other endocrine disruptors are assessed in testicular germ cell cancers. It may also represent a prognosis marker and/or a therapeutic target for seminomas.     

Retrograde transport of the transmembrane estrogen receptor, G-protein-coupled-receptor-30 (GPR30/GPER) from the plasma membrane towards the nucleus

G-protein-coupled receptor 30 (GPR30/GPER) belongs to the seven transmembrane receptor (7TMR) superfamily, the most common class of surface receptor with approximately 800 known members. GPER promotes estrogen binding and rapid signaling via membrane-associated enzymes resulting in increased cAMP and release of heparan bound epidermal growth factor (proHB-EGF) from breast cancer cells. However, GPER is predominately localized intracellularly in breast cancer cells with minor amounts of receptor on the cell surface, an observation that has caused some controversy regarding its potential role as a plasma membrane estrogen receptor. Using the widely employed approach of tracking recombinant 7TMRs by surface labeling live cells, we have begun to characterize and compare the endocytic fate of GPER to other similarly labeled 7TMRs. Upon ectopic expression in human embryonic kidney HEK-293 cells, functional GPER is generated as these cells acquire the capacity to stimulate cAMP and activate cyclic AMP responsive binding protein in response to estradiol-17 beta stimulation. GPER is detectable on the cell surface by immunofluorescent analysis using HA-specific antibodies, albeit the bulk of the receptor is located intracellularly. Like β1AR (beta 1 adrenergic receptor) and CXCR4 (C-X-C chemokine receptor 4), GPER exits the plasma membrane via clathrin-coated pits and enters early endosomes. Interestingly, GPER has a destination that is uncommon among 7TMRs, as it accumulates in a perinuclear compartment. Like many 7TMRs (approximately one-third), GPER trafficking from the plasma membrane is constitutive (occurs in the absence of agonist). However, its route of intracellular trafficking is highly unusual, as 7TMRs typically recycle to the plasma membrane (e.g. β1AR) or are degraded in lysosomes (e.g. CXCR4). The accumulation of GPER in the perinuclear space and its possible significance for attenuating estrogen action via this newly recognized membrane estrogen receptor is discussed herein.     

MMP-9、TIMP-1及细菌L型在卵巢乳头状癌中的表达及意义

目的探讨MMP-9、TIMP-1及细菌L型在卵巢上皮性肿瘤中的表达及临床意义。方法采用原位杂交和免疫组化及革兰染色方法检测97例卵巢乳头状癌及23例卵巢乳头状瘤组织中MMP-9、TIMP-1的表达及细菌L型检出率,并用2χ检验进行统计学处理。结果卵巢乳头状癌中MMP-9及TIMP-1的表达率均明显高于良性肿瘤(P<0.005)。MMP-9在卵巢乳头状癌中临床分期Ⅲ、Ⅳ期中的表达率明显高于Ⅰ、Ⅱ期(P<0.005~P<0.01),随着病理分级增高而显著增加(P<0.005~P<0.05),腹腔淋巴结有转移和有腹水者均高于无腹腔淋巴结转移和无腹水者(P<0.005~P<0.05)。而TIMP-1阳性表达与MMP-9阳性表达相反,呈负相关。细菌L型检出阳性率与病理分级及临床分期差异有显著性,腹腔淋巴结有转移比无转移者、有腹水比无腹水者差异有显著性(P<0.005)。结论MMP-9、TIMP-1基因及蛋白在卵巢肿瘤中有不同程度的异常表达,两者均可作为判断卵巢肿瘤生物学行为及患者预后参考指标。L型感染极有可能成为诱发肿瘤因素之一,它与MMP-9、TIMP-1可能有协同致瘤及恶性肿瘤侵袭和转移作用。研究细菌L型感染与肿瘤的关系,具有重要的临床应用价值。     

G15, a GPR30 antagonist,induces apoptosis and autophagy in human oral squamous carcinoma cells

As GPR30 has been implicated in mediating cancer cell proliferation, this study aimed to examine the antitumor effect of the GPR30 antagonist G15 in human oral squamous cell carcinoma (OSCC). G15 induced dose-dependent cytotoxicity, apoptosis and G2/M cell cycle arrest in a panel of OSCC cells. The results showed that G15 could inhibit the growth of the oral cancer cells with IC₅₀ value 11.2 μM for SCC4, 15.6 μM for SCC9, and 7.8 μM for HSC-3, respectively. Flow cytometric analysis and Comet assay indicated that G15 suppressed the viability of SCC4 and HSC-3 cells by inducing apoptosis and G2/M arrest. In addition, G15 down regulated the expression of Akt, cell cycle-related proteins, and mitogen-activated protein kinases, but increased the levels of LC3B-II and the accumulation of autophagosomes. Inhibition of autophagy by chloroquine does not affect the G15-induced apoptosis in SCC4 cells. Mechanistic evidence indicated that the antiproliferative effect was mediated through the downregulation of cdc2, cdc25c and NF-κB expression. Taken together, our findings suggest the potential of G15 in treating OSCC.