G-1 Inhibits Breast Cancer Cell Growth via Targeting Colchicine-Binding Site of Tubulin to Interfere with Microtubule Assembly

Suppressing Expression of SERPINE1/PAI1 Through Activation of GPER1 Reduces Progression of Vulvar Carcinoma

BACKGROUND/AIM

The serine proteinase inhibitor 1 (SERPINE1) gene codes for the plasminogen activator inhibitor 1 (PAI1) protein and is thought to play a tumor supportive role in various cancers. In this work we aimed to uncover the role PAI1 plays in the proliferation, migration, and invasion of vulvar cancer (VC), and define the protein's function as an oncogene or tumor suppressor.

MATERIALS AND METHODS

Through treatment with an agonist (G1) and antagonist (G36) of G-coupled estrogen receptor 1 (GPER1), an upstream regulator of SERPINE1 expression, and a forward transfection knockdown protocol, the expression of SERPINE1/PAI1 in VC cells was altered. The effects these altered SERPINE1/PAI1 levels had on tumor cell functions were then examined. Proliferation was analyzed using the resazurin assay, while migration was studied via the gap closure assay. Through colony- and tumor sphere- formation assays clonogenicity was tested, and western blots showed protein expression.

RESULTS

In A431 VC cells, when the levels of PAI1 were reduced via knockdown or treatment with G1, migration, proliferation, and colony growth was reduced. Treatment with G36 increased expression of PAI1 and increased migration and colony size in CAL39 cells.

CONCLUSION

Based on the findings in this study, suppressing PAI1 expression in VC cells appears to reduce their progression and tumorigenic potential. Therefore, PAI1 could possibly function as an oncogene in VC. GPER1 appears to be a suitable target for suppressing PAI1 in VC.

The G-Protein-Coupled Estrogen Receptor Agonist G-1 Mediates Antitumor Effects by Activating Apoptosis Pathways and Regulating Migration and Invasion in Cervical Cancer Cells

BACKGROUND/OBJECTIVES

Estrogens and HPV are necessary for cervical cancer (CC) development. The levels of the G protein-coupled estrogen receptor (GPER) increase as CC progresses, and HPV oncoproteins promote GPER expression. The role of this receptor is controversial due to its anti- and pro-tumor effects. This study aimed to determine the effect of GPER activation, using its agonist G-1, on the transcriptome, cell migration, and invasion in SiHa cells and non-tumorigenic keratinocytes transduced with the HPV16 E6 or E7 oncogenes.

METHODS

Transcriptome analysis was performed to identify G-1-enriched pathways in SiHa cells. We evaluated cell migration, invasion, and the expression of associated proteins in SiHa, HaCaT-16E6, and HaCaT-16E7 cells using various assays.

RESULTS

Transcriptome analysis revealed pathways associated with proliferation/apoptosis (TNF-α signaling, UV radiation response, mitotic spindle formation, G2/M cell cycle, UPR, and IL-6/JAK/STAT), cellular metabolism (oxidative phosphorylation), and cell migration (angiogenesis, EMT, and TGF-α signaling) in SiHa cells. Key differentially expressed genes included PTGS2 (pro/antitumor), FOSL1, TNFRSF9, IL1B, DIO2, and PHLDA1 (antitumor), along with under-expressed genes with pro-tumor effects that may inhibit proliferation. Additionally, DKK1 overexpression suggested inhibition of cell migration. G-1 increased vimentin expression in SiHa cells and reduced it in HaCaT-16E6 and HaCaT-16E7 cells. However, G-1 did not affect α-SMA expression or cell migration in any of the cell lines but increased invasion in HaCaT-16E7 cells.

CONCLUSIONS

GPER is a promising prognostic marker due to its ability to activate apoptosis and inhibit proliferation without promoting migration/invasion in CC cells. G-1 could potentially be a tool in the treatment of this neoplasia.

Exploring the antitumor potential of novel quinoline derivatives via tubulin polymerization inhibition in breast cancer; design, synthesis and molecular docking

A series of quinoline derivatives was designed and synthesized as novel tubulin inhibitors targeting the colchicine binding site. All the rationalized compounds 3a-e, 4a-e, 5a-e, and 6a-e have been chosen for screening their cytotoxic activity against 60 cell lines by NCI. Compounds 3b, 3c, 4c, 5c and 6c demonstrated the most notable antitumor activity against almost all cell lines. Compound 4c emerged as the most potent compound as an antiproliferative agent. This compound was subsequently chosen for five-dose testing and it exhibited remarkable broad-spectrum efficacy with strong antitumor activity against several cell lines. Compound 4c significantly induced cell cycle arrest in MDA-MB-231 cells at G2 and M phases where the cell population increased dramatically to 22.84% compared to the untreated cells at 10.42%. It also increased the population in MDA-MB-231 cells at both early and late stages of apoptosis. Compound 4c can successfully inhibit tubulin polymerization with an IC50 value of 17 ± 0.3 μM. The β-tubulin mRNA levels were notably reduced in MDA-MB-231 cells treated with compound 4c which is similar to the effect observed with colchicine treatment. Docking studies revealed that compound 4c interacted well with crucial amino acids in the active site.

Comprehensive understanding of the role of GPER in estrogen receptor-alpha negative breast cancer

G protein-coupled estrogen receptor (GPER) plays a prominent role in facilitating the rapid, non-genomic signaling of estrogens in breast cancer cells. Herein, a comprehensive overview of the role of GPER in ER-ɑ-negative breast cancer is provided. Activation of GPER affected proliferation, metastasis and epithelial mesenchymal transition in ER-ɑ negative breast cancer cells. Clinical studies have demonstrated that GPER positivity was strongly correlated with larger tumor size and advanced clinical stage, suggesting that GPER/ERK signaling may play a role in promoting tumor progression. Strong evidence existed that environmental contaminants like bisphenol A have a carcinogenic potential mediated by GPER activation. The complexity of the cross talk between GPER and other receptors including ER-β, ER-α36, Estrogen-related receptor α (ERRα) and androgen receptor has been discussed. The potential utility of small molecules and phytoestrogens targeting GPER, adds valuable insights into its therapeutic potential. This review holds promises in advancing our understanding of GPER role in ER-ɑ-negative breast cancer. Overall, the consequences of GPER activation are still an area of active research and the implication are not entirely clear.

The G-Protein-Coupled Estrogen Receptor Selective Agonist G-1 Attenuates Cell Viability and Migration in High-Grade Serous Ovarian Cancer Cell Lines

The G-protein-coupled estrogen receptor (GPER; G-protein-coupled estrogen receptor 30, also known as GPR30) is a novel estrogen receptor and has emerged as a promising target for ovarian cancer. GPER, a seven-transmembrane receptor, suppresses cellular viability and migration in studied ovarian cancer cells. However, its impact on the fallopian tube, which is the potential origin of high-grade serous (HGSC) ovarian cancer, has not been addressed. This study was conducted to evaluate the relationship of GPER, ovarian cancer subtypes, i.e., high-grade serous cell lines (OV90 and OVCAR420), as well as the cell type that is the potential origin of HGSC ovarian cancer (i.e., the fallopian tube cell line FT190). The selective ligand assessed here is the agonist G-1, which was utilized in an in vitro study to characterize its effects on cellular viability and migration. As a result, this study has addressed the effect of a specific GPER agonist on cell viability, providing a better understanding of the effects of this compound on our diverse group of studied cell lines. Strikingly, attenuated cell proliferation and migration behaviors were observed in the presence of G-1. Thus, our in vitro study reveals the impact of the origin of HGSC ovarian cancers and highlights the GPER agonist G-1 as a potential therapy for ovarian cancer.

Current progress and prospects for G protein-coupled estrogen receptor in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a biologically and clinically heterogeneous disease. The G protein-coupled estrogen receptor (GPER) plays a crucial role in mediating the effect of estrogen and estrogen-like compounds in TNBC cells. Compared with other subtypes, GPER has a higher expression in TNBC. The GPER mechanisms have been thoroughly characterized and analyzed in estrogen receptor α (ERα) positive breast cancer, but not in TNBC. Our previous work revealed that a higher expression of GPER mRNA indicates a better prognosis for ERα-positive breast cancer; however, its effects in TNBC differ. Whether GPER could serve as a predictive prognostic marker or therapeutic target for TNBC remains unclear. In this review, we provide a detailed introduction to the subcellular localization of GPER, the different effects of various ligands, and the interactions between GPER and closely associated factors in TNBC. We focused on the internal molecular mechanisms specific to TNBC and thoroughly explored the role of GPER in promoting tumor development. We also discussed the interaction of GPER with specific cytokines and chemokines, and the relationship between GPER and immune evasion. Additionally, we discussed the feasibility of using GPER as a therapeutic target in the context of existing studies. This comprehensive review highlights the effects of GPER on TNBC, providing a framework and directions for future research.

Different Expression Pattern of G Protein-Coupled Estrogen Receptor GPER1 in Esophageal Squamous Cell Carcinoma and Adenocarcinoma

Esophageal carcinoma is a male-dominant malignancy worldwide, and esophageal adenocarcinoma (EAC) shows more significant sex bias than esophageal squamous cell carcinoma (ESCC) in morbidity and mortality. The G protein-coupled estrogen receptor 1 (GPER1) is involved in several sex-related cancers; however, its expression level in esophageal carcinoma has been poorly investigated and its role is not precisely defined, depending on histological types. In the present study, the mRNA levels of GPER1 in esophageal carcinoma were collected from GEPIA and Oncomine databases for meta-analyses. The protein expression levels of GPER1 were detected by immunohistochemistry in the tissue microarray of EAC and ESCC. The GPER1 selective agonist G1, antagonist G15, and siRNA were applied in vitro to investigate their impacts on esophageal cell lines. Analysis of the RNA levels from the databases showed a decreased expression of GPER1 in overall esophageal carcinoma, and low expression levels of GPER1 were found to be associated with low survival of tumor patients. However, in the subgroup of EAC and its precancerous lesion, Barrett's esophagus, overexpression of GPER1 RNA was increased when compared with the normal tissues. The average staining scores of GPER1 protein in the tissue microarray of EAC were significantly higher than normal esophageal samples, and the rate of positive staining increased with the grade of poor tumor differentiation. The scores of GPER1 protein in ESCC tissues were lower than those in the normal tissues. The results from cell line experiments in vitro showed that the GPER1 agonist G1 inhibited proliferation and promoted apoptosis of ESCC cells EC109 with positive expression of GPER1. G1 had no obvious effect on normal esophageal NE2 cells with weak expression of GPER1. In addition, GPER1 RNA knockdown and application of antagonist G15 reversed the effects of G1 on EC109. The results of this study indicate that the expression levels of GPER1 are higher in EAC than in ESCC, which might be correlated with the dimorphic estrogen signaling pathway in different types of esophageal carcinoma.

2-Methoxyestradiol as an Antiproliferative Agent for Long-Term Estrogen-Deprived Breast Cancer Cells

To identify effective treatment modalities for breast cancer with acquired resistance, we first compared the responsiveness of estrogen receptor-positive breast cancer MCF-7 cells and long-term estrogen-deprived (LTED) cells (a cell model of endocrine therapy-resistant breast cancer) derived from MCF-7 cells to G-1 and 2-methoxyestradiol (2-MeO-E2), which are microtubule-destabilizing agents and agonists of the G protein-coupled estrogen receptor 1 (GPER1). The expression of GPER1 in LTED cells was low (~0.44-fold), and LTED cells displayed approximately 1.5-fold faster proliferation than MCF-7 cells. Although G-1 induced comparable antiproliferative effects on both MCF-7 and LTED cells (IC50 values of >10 µM), 2-MeO-E2 exerted antiproliferative effects selective for LTED cells with an IC50 value of 0.93 μM (vs. 6.79 μM for MCF-7 cells) and induced G2/M cell cycle arrest. Moreover, we detected higher amounts of β-tubulin proteins in LTED cells than in MCF-7 cells. Among the β-tubulin (TUBB) isotype genes, the highest expression of TUBB2B (~3.2-fold) was detected in LTED cells compared to that in MCF-7 cells. Additionally, siTUBB2B restores 2-MeO-E2-mediated inhibition of LTED cell proliferation. Other microtubule-targeting agents, i.e., paclitaxel, nocodazole, and colchicine, were not selective for LTED cells. Therefore, 2-MeO-E2 can be an antiproliferative agent to suppress LTED cell proliferation.

Activation of G-Protein-Coupled Estrogen Receptor 1 (GPER1) Reduces Progression of Vulvar Carcinoma Cells

Whether G protein-coupled estrogen receptor 1 (GPER1) is tumor-promoting or tumor-suppressive depends in part on tumor entity. Little is known about the function of GPER1 in vulvar carcinoma. In this work, we aim to clarify what role GPER1 plays in vulvar cancer, tumor-promoting or tumor-suppressive. Localization of GPER1 in A431 and CAL-39 vulvar carcinoma cells was examined by immunofluorescence. Using a tissue microarray of vulvar neoplasias, the correlation between GPER1 expression and grade of malignancy was investigated. A431 and CAL-39 cells were treated either with GPER1 agonist G1 or antagonist G36. Proliferation was quantified by BrdU assay and viability examined using Resazurin assay. Morphological changes were analyzed by microscopy and measured using ImageJ. Cell migration was analyzed by gap closure assay. Clonogenic potential was tested by colony and sphere formation. Expression of estrogen receptors was examined by Western blot. GPER1 was found consistently expressed in vulvar neoplasia tissues. The immune-reactive score was found to be significantly higher in tissue samples of lymph node metastases and neoplasias with grade 3. In A431 and CAL-39 vulvar carcinoma cells, GPER1 expression was mainly found in the cytoplasm and nuclei. Treatment of A431 and CAL-39 cells with GPER1 agonist G1 resulted in a decrease in proliferation and migration. In addition, colony formation and tumor sphere formation were reduced. Furthermore, morphological signs of necrosis and reduction in cell viability after G1 treatment were observed. The GPER1 antagonist G36 did not have significant effects on vulvar carcinoma cells. Neither agonist G1 nor antagonist G36 treatment resulted in altered expression of estrogen receptors. Activation of GPER1 with GPER1 agonist G1 reduces the tumorigenic potential of the vulvar carcinoma cells. It can be deduced from this that GPER1 appears to have a tumor-suppressive effect in vulvar carcinoma.

ASGARD is A Single-cell Guided Pipeline to Aid Repurposing of Drugs

Single-cell RNA sequencing technology has enabled in-depth analysis of intercellular heterogeneity in various diseases. However, its full potential for precision medicine has yet to be reached. Towards this, we propose A Single-cell Guided Pipeline to Aid Repurposing of Drugs (ASGARD) that defines a drug score to recommend drugs by considering all cell clusters to address the intercellular heterogeneity within each patient. ASGARD shows significantly better average accuracy on single-drug therapy compared to two bulk-cell-based drug repurposing methods. We also demonstrated that it performs considerably better than other cell cluster-level predicting methods. In addition, we validate ASGARD using the drug response prediction method TRANSACT with Triple-Negative-Breast-Cancer patient samples. We find that many top-ranked drugs are either approved by the Food and Drug Administration or in clinical trials treating corresponding diseases. In conclusion, ASGARD is a promising drug repurposing recommendation tool guided by single-cell RNA-seq for personalized medicine. ASGARD is free for educational use at https://github.com/lanagarmire/ASGARD .

Molecular Characterization of the Dual Effect of the GPER Agonist G-1 in Glioblastoma

Glioblastoma (GBM) is the most common primary brain tumor in adults. Despite conventional treatment, consisting of a chirurgical resection followed by concomitant radio-chemotherapy, the 5-year survival rate is less than 5%. Few risk factors are clearly identified, but women are 1.4-fold less affected than men, suggesting that hormone and particularly estrogen signaling could have protective properties. Indeed, a high GPER1 (G-protein-coupled estrogen receptor) expression is associated with better survival, especially in women who produce a greater amount of estrogen. Therefore, we addressed the anti-tumor effect of the GPER agonist G-1 in vivo and characterized its molecular mechanism of action in vitro. First, the antiproliferative effect of G-1 was confirmed in a model of xenografted nude mice. A transcriptome analysis of GBM cells exposed to G-1 was performed, followed by functional analysis of the differentially expressed genes. Lipid and steroid synthesis pathways as well as cell division processes were both affected by G-1, depending on the dose and duration of the treatment. ANGPTL4, the first marker of G-1 exposure in GBM, was identified and validated in primary GBM cells and patient samples. These data strongly support the potential of G-1 as a promising chemotherapeutic compound for the treatment of GBM.

Therapeutic activation of G protein-coupled estrogen receptor 1 in Waldenström Macroglobulinemia

Activating G protein-coupled estrogen receptor 1 (GPER1) is an attractive therapeutic strategy for treating a variety of human diseases including cancer. Here, we show that GPER1 is significantly upregulated in tumor cells from different cohorts of Waldenström Macroglobulinemia (WM) patients compared to normal B cells. Using the clinically applicable GPER1-selective small-molecule agonist G-1 (also named Tespria), we found that pharmacological activation of GPER1 leads to G2/M cell cycle arrest and apoptosis both in vitro and in vivo in animal models, even in the context of the protective bone marrow milieu. Activation of GPER1 triggered the TP53 pathway, which remains actionable during WM progression. Thus, this study identifies a novel therapeutic target in WM and paves the way for the clinical development of the GPER1 agonist G-1.

Human papillomavirus targets the YAP1-LATS2 feedback loop to drive cervical cancer development

Human papillomavirus (HPV) infection is very common in sexually active women, but cervical cancer only develops in a small fraction of HPV-infected women, suggesting that unknown intrinsic factors associated with the unique genetic/genomic background of the high-risk population play a critical role in cervical carcinogenesis. Although our previous studies have identified the hyperactivated YAP1 oncogene as a critical contributor to cervical cancer, the molecular mechanism by which YAP1 drives cervical cancer is unknown. In the present study, we found that although the hyperactivated YAP1 caused a malignant transformation of immortalized cervical epithelial cells, it induced cellular senescence in cultures of primary human cervical epithelial cells (HCvECs). However, the hyperactivated YAP1 induced malignant transformation of HCvECs in the presence of high-risk HPV E6/E7 proteins, suggesting that the hyperactivated YAP1 synergizes with HPV to initiate cervical cancer development. Our mechanistic studies demonstrate that YAP1, via up-regulating LATS2, formed a YAP1-LATS2 negative feedback loop in cervical epithelial cells to maintain homeostasis of cervical tissue. Intriguingly, we found that high-risk HPV targets LATS2 to disrupt the feedback loop leading to the malignant transformation of cervical epithelial cells. Finally, we report that mitomycin C, an FDA-approved drug that could upregulate LATS2 and drive cellular senescence in vitro and in vivo, induced a regression of cervical cancer in a pre-clinial animal model. Thus, high-risk HPV targeting the YAP1-LATS2 feedback loop represents a new mechanism of cervical cancer development.

Novel GPER Agonist, CITFA, Increases Neurite Growth in Rat Embryonic (E18) Hippocampal Neurons

Numerous studies have reported neuroprotective and procognitive effects of estrogens. The estrogen 17β-estradiol (E2) activates both the classical nuclear estrogen receptors ERα and ERβ as well as the G protein-coupled estrogen receptor (GPER). The differential effects of targeting the classical estrogen receptors over GPER are not well-understood. A limited number of selective GPER compounds have been described. In this study, 10 novel compounds were synthesized and exhibited half-maximal effective concentration values greater than the known GPER agonist G-1 in calcium mobilization assays performed in nonadherent HL-60 cells. Of these compounds, 2-cyclohexyl-4-isopropyl-N-((5-(tetrahydro-2H-pyran-2-yl)furan-2-yl)methyl)aniline, referred to as CITFA, significantly increased axonal and dendritic growth in neurons extracted from embryonic day 18 (E18) fetal rat hippocampal neurons. Confirmation of the results was performed by treating E18 hippocampal neurons with known GPER-selective antagonist G-36 and challenging with either E2, G-1, or CITFA. Results from these studies revealed an indistinguishable difference in neurite outgrowth between the treatment and control groups, exhibiting that neurite outgrowth in response to G-1 and CITFA originates from GPER activation and can be abolished with pretreatment of an antagonist. Subsequent docking studies using a homology model of GPER showed unique docking poses between G-1 and CIFTA. While docking poses differed between the ligands, CIFTA exhibited more favorable distance, bond angle, and strain for hydrogen-bonding and hydrophobic interactions.

The G-Protein–Coupled Estrogen Receptor Agonist G-1 Inhibits Proliferation and Causes Apoptosis in Leukemia Cell Lines of T Lineage

The G-protein–coupled estrogen receptor (GPER) mediates non-genomic action of estrogen. Due to its differential expression in some tumors as compared to the original healthy tissues, the GPER has been proposed as a therapeutic target. Accordingly, the non-steroidal GPER agonist G-1, which has often demonstrated marked cytotoxicity in experimental models, has been suggested as a novel anticancer agent for several sensitive tumors. We recently revealed that cell lines derived from acute T-cell (query) lymphoblastic leukemia (T-ALL) express the GPER. Here, we address the question whether G-1 is cytotoxic to T-ALL. We have shown that G-1 causes an early rise of intracellular Ca²⁺, arrests the cell cycle in G2/M, reduces viability, and provokes apoptosis in T-ALL cell lines. Importantly, G-1 caused destabilization and depolymerization of microtubules. We assume that it is a disturbance of the cytoskeleton that causes G-1 cytotoxic and cytostatic effects in our model. The observed cytotoxic effects, apparently, were not triggered by the interaction of G-1 with the GPER as pre-incubation with the highly selective GPER antagonist G-36 was ineffective in preventing the cytotoxicity of G-1. However, G-36 prevented the intracellular Ca²⁺ rise provoked by G-1. Finally, G-1 showed only a moderate negative effect on the activation of non-leukemic CD4⁺ lymphocytes. We suggest G-1 as a potential antileukemic drug.

GPER Agonist G-1 Disrupts Tubulin Dynamics and Potentiates Temozolomide to Impair Glioblastoma Cell Proliferation

Glioblastoma (GBM) is the most common brain tumor in adults, which is very aggressive, with a very poor prognosis that affects men twice as much as women, suggesting that female hormones (estrogen) play a protective role. With an in silico approach, we highlighted that the expression of the membrane G-protein-coupled estrogen receptor (GPER) had an impact on GBM female patient survival. In this context, we explored for the first time the role of the GPER agonist G-1 on GBM cell proliferation. Our results suggested that G-1 exposure had a cytostatic effect, leading to reversible G2/M arrest, due to tubulin polymerization blockade during mitosis. However, the observed effect was independent of GPER. Interestingly, G-1 potentiated the efficacy of temozolomide, the current standard chemotherapy treatment, since the combination of both treatments led to prolonged mitotic arrest, even in a temozolomide less-sensitive cell line. In conclusion, our results suggested that G-1, in combination with standard chemotherapy, might be a promising way to limit the progression and aggressiveness of GBM.

Identifying the Effect of Ursolic Acid Against Triple-Negative Breast Cancer: Coupling Network Pharmacology With Experiments Verification

Triple negative breast cancer (TNBC) is a subtype of breast cancer with complex heterogeneity, high invasiveness, and long-term poor prognosis. With the development of molecular pathology and molecular genetics, the gene map of TNBC with distinctive biological characteristics has been outlined more clearly. Natural plant extracts such as paclitaxel, vinblastine, colchicine etc., have occupied an important position in the treatment of hormone-independent breast cancer. Ursolic acid (UA), a triterpenoid acid compound derived from apple, pear, loquat leaves, etc., has been reported to be effective in a variety of cancer treatments, but there are few reports on the treatment of TNBC. This study performed comprehensive bioinformatics analysis and in vitro experiments to identify the effect of UA on TNBC treatment and its potential molecular mechanism. Our results showed that UA could not only reduce the proliferation, migration, and invasion in MDA-MB-231 and MDA-MB-468 cell lines with a dose-dependent manner but also induce cell cycle arrest and apoptosis. Meanwhile, we collected the gene expression data GSE45827 and GSE65194 from GEO for comparison between TNBC and normal cell type and obtained 724 DEGs. Subsequently, PLK1 and CCNB1 related to TNBC were screened as the key targets via topological analysis and molecular docking, and gene set enrichment analysis identified the key pathway as the p53 signaling pathway. In addition, quantitative real-time PCR and western blot verified the key genes were PLK1 and CCNB1. In vivo and in vitro experiments showed that UA could inhibit the growth of TNBC cells, and down-regulate the protein expression levels of PLK1 and CCNB1 by mediating p53 signaling pathway. These findings provide strong evidence for UA intervention in TNBC via multi-target therapy.

4-Methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP) Targets Estrogen Receptor β, to Evoke the Resistance of Human Breast Cancer MCF-7 Cells to G-1, an Agonist for G Protein-Coupled Estrogen Receptor 1

Bisphenol A (BPA) has been shown to induce the activation of nuclear estrogen receptor α/β (ERα/β) in both in vitro and in vivo settings. We originally obtained a 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP), a possible active metabolite of BPA, strongly activating the ERs-mediated transcription in MCF-7 cells with an EC₅₀ of 2.8 nM (i.e., BPA's EC₅₀ = 519 nM). Environmental estrogens can also target G protein-coupled estrogen receptor 1 (GPER1), a membrane-type ER. However, the effects of BPA/MBP on GPER1, have not yet been fully resolved. In this study, we used MCF-7, a ERα/ERβ/GPER1-positive human breast cancer cell line, as a model to investigate the effects of the exposure to BPA or MBP. Our results revealed that at concentrations below 1 nM MBP, but not BPA, downregulates the expression of GPER1 mRNA via upregulated ERβ, and the MCF-7 cells pre-treated with MBP display resistance to GPER1 agonist G-1-mediated anti-proliferative effects. Because GPER1 can act as a tumor suppressor in several types of cancer including breast cancer, the importance of MBP-mediated decrease in GPER1 expression in breast cancer cells is discussed.

G Protein-Coupled Estrogen Receptor Agonist G-1 Inhibits Mantle Cell Lymphoma Growth in Preclinical Models

Mantle cell lymphoma (MCL) is an aggressive form of non-Hodgkin’s B-cell lymphoma with poor prognosis. Despite recent advances, resistance to therapy and relapse remain significant clinical problems. G-protein-coupled estrogen receptor (GPER)-mediated estrogenic rapid signaling is implicated in the development of many cancers. However, its role in MCL is unknown. Here we report that GPER activation with selective agonist G-1 induced cell cycle arrest, DNA damage, mitochondria membrane potential abnormality, and eventually apoptosis of MCL cell lines. We found that G-1 induced DNA damage and apoptosis of MCL cells by promoting the expression of nicotinamide adenine dinucleotide phosphate oxidase and the generation of reactive oxygen species. In addition, G-1 inhibited MCL cell proliferation by inactivation of NF-κB signaling and exhibited anti-tumor functions in MCL xenografted mice. Most significantly, G-1 showed synergistic effect with ibrutinib making it a potential candidate for chemotherapy-free therapies against MCL.

Synthesis and biological evaluation of new 2-methoxyestradiol derivatives: Potent inhibitors of angiogenesis and tubulin polymerization

Here, we report the structural optimization of a hit natural compound, 2-ME₂ (2-methoxyestradiol), which exhibited inhibitory activity but low potency on tubulin polymerization, anti- angiogenesis, MCF-7 proliferation and metastasis in vitro and in vivo. A novel series of 3,17-modified and 17-modified analogs of 2-ME₂ were synthesized and investigated for their antiproliferative activity against MCF-7 and another five different human cancer cell lines leading to the discovery of 9i. 9i bind to tubulin colchicine site tightly, inhibited tubulin polymerization and disrupted cellular microtubule networks. Cellular mechanism studies revealed that 9i could induce G2/M phase arrest by down-regulated expression of p-Cdc2, P21 and cell apoptosis by regulating apoptosis-related proteins (Parp, Caspase families) in a dose-dependent manner. Importantly, 9i significantly inhibited HUVEC tube formation, proliferation, migration and invasion. The inhibitory effect against angiogenesis in vivo was confirmed by zebrafish xenograft. Furthermore, 9i could effectively inhibit the proliferation and metastasis of MCF-7 cells in vitro and in zebrafish xenograft. The satisfactory physicochemical property and metabolic stability of 9i further indicated that it can act as a promising and potent anti-angiogenesis, inhibiting proliferation and metastasis of breast cancer agent via targeting tubulin colchicine binding site.

Reprogramming of Ovarian Granulosa Cells by YAP1 Leads to Development of High-Grade Cancer with Mesenchymal Lineage and Serous Features

Understanding the cell-of-origin of ovarian high grade serous cancer (HGSC) is the prerequisite for efficient prevention and early diagnosis of this most lethal gynecological cancer. Recently, a mesenchymal type of ovarian HGSC with the poorest prognosis among ovarian cancers was identified by both TCGA and AOCS studies. The cell-of-origin of this subtype of ovarian cancer is unknown. While pursuing studies to understand the role of the Hippo pathway in ovarian granulosa cell physiology and pathology, we unexpectedly found that the Yes-associated protein 1 (YAP1), the major effector of the Hippo signaling pathway, induced dedifferentiation and reprogramming of the ovarian granulosa cells, a unique type of ovarian follicular cells with mesenchymal lineage and high plasticity, leading to the development of high grade ovarian cancer with serous features. Our research results unveil a potential cell-of-origin for a subtype of HGSC with mesenchymal features.

A Human Papillomavirus-Independent Cervical Cancer Animal Model Reveals Unconventional Mechanisms of Cervical Carcinogenesis

HPV infections are common in healthy women and only rarely cause cervical cancer, suggesting that individual genetic susceptibility may play a critical role in the establishment of persistent HPV infection and the development of cervical cancer. Here, we provide convincing in vitro and in vivo evidence showing that differential expression and activation of YAP1 oncogene determine individual susceptibility to HPV infection and cervical carcinogenesis. We found that hyperactivation of YAP1 in mouse cervical epithelium was sufficient to induce invasive cervical cancer. Cervical epithelial cell-specific HPV16 E6/E7 and YAP1 double-knockin mouse model demonstrated that high-risk HPV synergized with hyperactivated YAP1 to promote the initiation and progression of cervical cancer. Our mechanistic studies indicated that hyperactivation of YAP1 in cervical epithelial cells facilitated HPV infection by increasing the putative HPV receptor molecules and disrupting host cell innate immunity. Our finding reveals an unconventional mechanism for cervical carcinogenesis.

HPV infections are common in healthy women and only rarely cause cervical cancer. He et al. provide evidence that hyperactivation of the YAP1 oncogene can drive cervical cancer initiation and progression. YAP1 hyperactivation in cervical epithelial cells increases the HPV receptors and disrupts host cell innate immunity, facilitating HPV infection.

Understanding Breast cancer: from conventional therapies to repurposed drugs

Breast cancer is the most common cancer among women and is considered a developed country disease. Moreover, is a heterogenous disease, existing different types and stages of breast cancer development, therefore, better understanding of cancer biology, helps to improve the development of therapies. The conventional treatments accessible after diagnosis, have the main goal of controlling the disease, by improving survival. In more advance stages the aim is to prolong life and symptom palliation care. Surgery, radiation therapy and chemotherapy are the main options available, which must be adapted to each person individually. However, patients are developing resistance to the conventional therapies. This resistance is due to alterations in important regulatory pathways such as PI3K/AKt/mTOR, this pathway contributes to trastuzumab resistance, a reference drug to treat breast cancer. Therefore, is proposed the repurposing of drugs, instead of developing drugs de novo, for example, to seek new medical treatments within the drugs available, to be used in breast cancer treatment. Providing safe and tolerable treatments to patients, and new insights to efficacy and efficiency of breast cancer treatments. The economic and social burden of cancer is enormous so it must be taken measures to relieve this burden and to ensure continued access to therapies to all patients. In this review we focus on how conventional therapies against breast cancer are leading to resistance, by reviewing those mechanisms and discussing the efficacy of repurposed drugs to fight breast cancer.

Expression and Role of the G Protein-Coupled Estrogen Receptor (GPR30/GPER) in the Development and Immune Response in Female Reproductive Cancers

Cancer is a major public health issue and represents the second leading cause of death in women worldwide, as female reproductive-related neoplasms are the main cause of incidence and mortality. Female reproductive cancers have a close relationship to estrogens, the principal female sex steroid hormones. Estrogens exert their actions by the nuclear estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ). ERα, and ERβ act as transcription factors mediating genomic effects. Besides, the G protein-coupled estrogen receptor (GPER, formerly known as GPR30) was recently described as a seven-transmembrane receptor that mediates non-genomic estrogenic signaling, including calcium mobilization, cAMP synthesis, cleavage of matrix metalloproteinases, transactivation of epidermal growth factor receptor (EGFR), and the subsequent activation of PI3K and MAPK signaling pathways, which are the reasons why it is related to cellular processes, such as cell-cycle progression, cellular proliferation, differentiation, apoptosis, migration, and invasion. Since its discovery, selective agonists and antagonists have been found and developed. GPER has been implicated in a variety of hormone-responsiveness tumors, such as breast, endometrial, ovarian, cervical, prostate, and testicular cancer as well as lung, hepatic, thyroid, colorectal, and adrenocortical cancers. Nevertheless, GPER actions in cancer are still debatable due to the conflicting information that has been reported to date, since many reports indicate that activation of this receptor can modulate carcinogenesis. In contrast, many others show that its activation inhibits tumor activity. Besides, estrogens play an essential role in the regulation of the immune system, but little information exists about the role of GPER activation on its modulation within cancer context. This review focuses on the role that the stimulation of GPER plays in female reproductive neoplasms, specifically breast, endometrial, ovarian, and cervical cancers, in its tumor activity and immune response regulation.

2-Methoxyestradiol and Its Combination with a Natural Compound, Ferulic Acid, Induces Melanoma Cell Death via Downregulation of Hsp60 and Hsp90

Melanoma is an aggressive type of skin cancer with one of the highest mortality rates. Notably, its incidence in the last few decades has increased faster than any other cancer. Therefore, searching for novel anticancer therapies is of great clinical importance. In the present study, we investigated the anticancer potential of 2-methoxyestradiol, potent chemotherapeutic, in the A375 melanoma cellular model. In order to furthermore evaluate the anticancer efficacy of 2-methoxyestradiol, we have additionally combined the treatment with a naturally occurring polyphenol, ferulic acid. The results were obtained using the melanoma A375 cellular model. In the study, we used MTT assay, flow cytometry, and western blot techniques. Herein, we have evidenced that the molecular mechanism of action of 2-methoxyestradiol and ferulic acid is partly related to the reduction of Hsp60 and Hsp90 levels and the induction of nitric oxide in the A375 melanoma cell model, while no changes were observed in Hsp70 expression after 2-methoxyestradiol and ferulic acid treatment separately or in combination. This is especially important in case of chemoresistance mechanisms because the accumulation of Hsp70 reduces induction of cancer cell death, thus decreasing antitumour efficacy.

Prognostic role of GPER/Ezrin in triple-negative breast cancer is associated with menopausal status

The role of G protein-coupled estrogen receptor 1 (GPER) signaling, including promotion of Ezrin phosphorylation (which could be activated by estrogen), has not yet been clearly identified in triple-negative breast cancer (TNBC). This study aimed to evaluate the prognostic value of GPER and Ezrin in TNBC patients. Clinicopathologic features including age, menopausal status, tumor size, nuclear grade, lymph node metastasis, AJCC TNM stage, and ER, PR and HER-2 expression were evaluated from 249 TNBC cases. Immunohistochemical staining of GPER and Ezrin was performed on TNBC pathological sections. Kaplan-Meier analyses, as well as logistic regressive and Cox regression model tests were applied to evaluate the prognostic significance between different subgroups. Compared to the GPER-low group, the GPER-high group exhibited higher TNM staging (P = 0.021), more death (P < 0.001), relapse (P < 0.001) and distant events (P < 0.001). Kaplan-Meier analysis showed that GPER-high patients had a decreased OS (P < 0.001), PFS (P < 0.001), LRFS (P < 0.001) and DDFS (P < 0.001) than GPER-low patients. However, these differences in prognosis were not statistically significant in post-menopausal patients (OS, P = 0.8617; PFS, P = 0.1905; LRFS, P = 0.4378; DDFS, P = 0.2538). There was a significant positive correlation between GPER and Ezrin expression level (R = 0.508, P < 0.001) and the effect of Ezrin on survival prognosis corresponded with GPER. Moreover, a multivariable analysis confirmed that GPER and Ezrin level were both significantly associated with poor DDFS (HR: 0.346, 95% CI 0.182-0.658, P = 0.001; HR: 0.320, 95% CI 0.162-0.631, P = 0.001). Thus, overexpression of GPER and Ezrin may contribute to aggressive behavior and indicate unfavorable prognosis in TNBC; this may correspond to an individual's estrogen levels.

Antitumor effect of XCT790, an ERRα inverse agonist, on ERα-negative endometrial cancer cells

PURPOSE

The estrogen-related receptor (ERR) α is structurally similar to classical estrogen receptors (ERs), but is considered to be an orphan nuclear receptor. We previously found that ERRα regulates uterine endometrial cancer progression. Here, we investigated the efficacy of XCT790, a selective inverse agonist of ERRα, on endometrial cancer cells in vitro and in vivo.

METHODS

HEC-1A and KLE, ERα-negative endometrial cancer cells exhibiting high ERRα expression levels, and HEC-1A cell-derived xenograft model mice were treated with XCT790. Transcriptional activity and cell proliferation were examined using luciferase, WST-8 and colony formation assays, respectively. Cell cycle progression was evaluated using flow cytometry, immunofluorescence cytochemistry and Western blotting. Apoptosis was evaluated using a caspase-3/7 activity assay.

RESULTS

We found that XCT790 significantly inhibited ERRα-induced in vitro transcriptional activity, including that of the vascular endothelial growth factor (VEGF) gene, in a concentration-dependent manner (p < 0.05). We also found that XCT790 suppressed colony formation and cell proliferation in a concentration and time-dependent manner (p < 0.01) without cytotoxicity, and induced apoptosis (p < 0.01). XCT790 was found to cause cell cycle arrest at the mitotic phase. Akt and mTOR phosphorylation was found to be inhibited by XCT790, but PI3K levels were not found to be significantly affected. Combination therapy of XCT790 with paclitaxel elicited a synergistic inhibitory effect. Additionally, we found that XCT790 significantly inhibited in vivo tumor growth and angiogenesis, and induced apoptosis without a reduction in body weight, in xenograft models (p < 0.01).

CONCLUSIONS

From our data we conclude that XCT790 has an anti-tumor effect on endometrial cancer cells in vitro and in vivo. As such, it may serve as a novel therapeutic agent for endometrial cancer.

YAP1-LATS2 feedback loop dictates senescent or malignant cell fate to maintain tissue homeostasis

Dysfunction of the homeostasis-maintaining systems in specific cell types or tissues renders the organism susceptible to a range of diseases, including cancers. One of the emerging mechanisms for maintaining tissue homeostasis is cellular senescence. Here, we report that the Hippo pathway plays a critical role in controlling the fate of ovarian cells. Hyperactivation of Yes-associated protein 1 (YAP1), the major effector of the Hippo pathway, induces senescence in cultured primary human ovarian surface epithelial cells (hOSEs). Large tumor suppressor 2 (LATS2), the primary upstream negative regulator of YAP1, is elevated in both YAP1-induced and natural replicative-triggered senescence. Deletion of LATS2 in hOSEs prevents these cells from natural replicative and YAP1-induced senescence. Most importantly, loss of LATS2 switches ovarian cells from YAP-induced senescence to malignant transformation. Our results demonstrate that LATS2 and YAP1, two major components of the Hippo/YAP signaling pathway, form a negative feedback loop to control YAP1 activity and prevent ovarian cells from malignant transformation. Human cancer genomic data extracted from TCGA datasets further confirm the clinical relevance of our finding.

A Series of Indole-Thiazole Derivatives Act as GPER Agonists and Inhibit Breast Cancer Cell Growth

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 5 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.

LncRNAs regulate the cytoskeleton and related Rho/ROCK signaling in cancer metastasis

Some of the key steps in cancer metastasis are the migration and invasion of tumor cells; these processes require rearrangement of the cytoskeleton. Actin filaments, microtubules, and intermediate filaments involved in the formation of cytoskeletal structures, such as stress fibers and pseudopodia, promote the invasion and metastasis of tumor cells. Therefore, it is important to explore the mechanisms underlying cytoskeletal regulation. The ras homolog family (Rho) and Rho-associated coiled-coil containing protein serine/threonine kinase (ROCK) signaling pathway is involved in the regulation of the cytoskeleton. Moreover, long noncoding RNAs (lncRNAs) have essential roles in tumor migration and guide gene regulation during cancer progression. LncRNAs can regulate the cytoskeleton directly or may influence the cytoskeleton via Rho/ROCK signaling during tumor migration. In this review, we focus on the regulatory association between lncRNAs and the cytoskeleton and discuss the pathways and mechanisms involved in the regulation of cancer metastasis.