Characterization of a selective inverse agonist for estrogen related receptor α as a potential agent for breast cancer

Dihydroartemisinin suppresses glioma growth by repressing ERRα-mediated mitochondrial biogenesis

Malignant gliomas are an exceptionally lethal form of cancer with limited treatment options. Dihydroartemisinin (DHA), a sesquiterpene lactone antimalarial compound, has demonstrated therapeutic effects in various solid tumors. In our study, we aimed to investigate the mechanisms underlying the anticancer effects of DHA in gliomas. To explore the therapeutic and molecular mechanisms of DHA, we employed various assays, including cell viability, flow cytometry, mitochondrial membrane potential, glucose uptake and glioma xenograft models. Our data demonstrated that DHA significantly inhibited glioma cell proliferation in both temozolomide-resistant cells and glioma stem-like cells. We found that DHA-induced apoptosis occurred via the mitochondria-mediated pathway by initiating mitochondrial dysfunction before promoting apoptosis. Moreover, we discovered that DHA treatment substantially reduced the expression of the mitochondrial biogenesis-related gene, ERRα, in glioma cells. And the ERRα pathway is a critical target in treating glioma with DHA. Our results also demonstrated that the combination of DHA and temozolomide synergistically inhibited the proliferation of glioma cells. In vivo, DHA treatment remarkably extended survival time in mice bearing orthotopic glioblastoma xenografts. Thus, our findings suggest that DHA has a novel role in modulating cancer cell metabolism and suppressing glioma progression by activating the ERRα-regulated mitochondrial apoptosis pathway.

International Union of Basic and Clinical Pharmacology CXIII: Nuclear Receptor Superfamily-Update 2023

The NR superfamily comprises 48 transcription factors in humans that control a plethora of gene network programs involved in a wide range of physiologic processes. This review will summarize and discuss recent progress in NR biology and drug development derived from integrating various approaches, including biophysical techniques, structural studies, and translational investigation. We also highlight how defective NR signaling results in various diseases and disorders and how NRs can be targeted for therapeutic intervention via modulation via binding to synthetic lipophilic ligands. Furthermore, we also review recent studies that improved our understanding of NR structure and signaling. SIGNIFICANCE STATEMENT: Nuclear receptors (NRs) are ligand-regulated transcription factors that are critical regulators of myriad physiological processes. NRs serve as receptors for an array of drugs, and in this review, we provide an update on recent research into the roles of these drug targets.

Development and pharmacological evaluation of a new chemical series of potent pan-ERR agonists, identification of SLU-PP-915

Estrogen-related receptors (ERR) are an orphan nuclear receptor sub-family that play a critical role in regulating gene transcription for several physiological processes including mitochondrial function, cellular energy utilization and homeostasis. They have also been implicated to play a role in several pathological conditions. Herein, we report the identification, synthesis, structure-activity relationships and pharmacological evaluation of a new chemical series of potent pan-ERR agonists. This template was designed for ERRγ starting from the known acyl hydrazide template and compounds such as agonist GSK-4716 employing a structure-based drug design approach. This led to the preparation of a series of 2,5-disubstituted thiophenes from which several were found to be potent agonists of ERRγ in cell-based co-transfection assays. Additionally, direct binding to ERRγ was established through 1H NMR protein-ligand binding experiments. Compound optimization revealed that the phenolic or aniline groups could be replaced with a boronic acid moiety, which was able to maintain activity and demonstrated improved metabolic stability in microsomal in vitro assays. Further pharmacological evaluation of these compounds showed that they had roughly equivalent agonist activity on ERR isoforms α and β representing an ERR pan-agonist profile. One potent agonist, SLU-PP-915 (10s), which contained a boronic acid moiety was profiled in gene expression assays and found to significantly upregulate the expression of ERR target genes such as peroxisome-proliferator activated receptor γ co-activators-1α, lactate dehydrogenase A, DNA damage inducible transcript 4 and pyruvate dehydrogenase kinase 4 both in vitro and in vivo.

The discovery of a novel series of potential ERRα inverse agonists based on p-nitrobenzenesulfonamide template for triple-negative breast cancer in vivo

Oestrogen related receptor α participated in the regulation of oxidative metabolism and mitochondrial biogenesis, and was overexpressed in many cancers including triple-negative breast cancer. A set of new ERRα inverse agonists based on p-nitrobenzenesulfonamide template were discovered and compound 11 with high potent activity (IC50 = 0.80 μM) could significantly inhibit the transcription of ERRα-regulated target genes. By regulating the downstream signalling pathway, compound 11 could suppress the migration and invasion of the ER-negative MDA-MB-231 cell line. Furthermore, compound 11 demonstrated a significant growth suppression of breast cancer xenograft tumours in vivo (inhibition rate 23.58%). The docking results showed that compound 11 could form hydrogen bonds with Glu331 and Arg372 in addition to its hydrophobic interaction with ligand-binding domain. Our data implied that compound 11 represented a novel and effective ERRα inverse agonist, which had broad application prospects in the treatment of triple-negative breast cancer.

PGC-1β and ERRα Promote Glutamine Metabolism and Colorectal Cancer Survival via Transcriptional Upregulation of PCK2

BACKGROUND

Previous studies have shown that Peroxisome Proliferator-Activated Receptor Gamma, Coactivator 1 Beta (PGC-1β) and Estrogen-Related Receptor Alpha (ERRα) are over-expressed in colorectal cancer and promote tumor survival.

METHODS

In this study, we use immunoprecipitation of epitope tagged endogenous PGC-1β and inducible PGC-1β mutants to show that amino acid motif LRELL on PGC-1β is responsible for the physical interaction with ERRα and promotes ERRα mRNA and protein expression. We use RNAsequencing to determine the genes regulated by both PGC-1β & ERRα and find that mitochondrial Phosphoenolpyruvate Carboxykinase 2 (PCK2) is the gene that decreased most significantly after depletion of both genes.

RESULTS

Depletion of PCK2 in colorectal cancer cells was sufficient to reduce anchorage-independent growth and inhibit glutamine utilization by the TCA cycle. Lastly, shRNA-mediated depletion of ERRα decreased anchorage-independent growth and glutamine metabolism, which could not be rescued by plasmid derived expression of PCK2.

DISCUSSION

These findings suggest that transcriptional control of PCK2 is one mechanism used by PGC-1β and ERRα to promote glutamine metabolism and colorectal cancer cell survival.

Ixazomib Induces Apoptosis and Suppresses Proliferation in Esophageal Squamous Cell Carcinoma through Activation of the c-Myc/NOXA Pathway

Esophageal squamous cell carcinoma (ESCC) is one of the major subtypes of esophageal cancer. More than half of the patients with ESCC in the world are in China, and the 5-year survival rate is less than 10%. As a new oral proteasome inhibitor, ixazomib has shown strong therapeutic effect in many solid tumors. In this study, we aimed to investigate the effects of ixazomib on the proliferation inhibition and apoptosis of ESCC cells. We used four human ESCC cell lines, cell viability assay, cell cycle and apoptosis assay, reverse-transcription polymerase chain reaction (RT-PCR), Western blot, immunohistochemistry, and ESCC xenografts model to clarify the roles of the therapeutic effect and mechanism of ixazomib in ESCC. Ixazomib significantly inhibited the proliferation and induced apoptosis in ESCC cells. RT-PCR results showed that the expressions of endoplasmic reticulum stress-related gene phorbol-12-myristate-13-acetate-induced protein 1 (NOXA) and MYC proto-oncogene (c-Myc) significantly increase after treatment with ixazomib in ESCC cells. When we knocked down the NOXA and c-Myc by small interfering RNA, the therapeutic effect of ixazomib markedly decreased, which confirmed that c-Myc/NOXA pathway played a key role in the treatment of ESCC with ixazomib. In vivo, the xenograft ESCC model mice were given 10 mg/kg of ixazomib every other day for 30 days. The results showed that the tumor size in the treatment group was significantly smaller than the control group. These results suggested that ixazomib is known to suppress proliferation and induce apoptosis in ESCC cell lines, and this effect was likely mediated by increased activation of the c-Myc/NOXA signaling pathways. SIGNIFICANCE STATEMENT: Esophageal squamous cell carcinoma (ESCC) is the common worldwide malignant tumor, but conventional chemotherapeutics suffer from a number of limitations. In this study, the results suggested that ixazomib suppresses proliferation and induces apoptosis in ESCC cell lines. Therefore, ixazomib may be a potential new strategy for ESCC therapy.

Molecular Dynamics Simulations Based on 1-Phenyl-4-Benzoyl-1-Hydro-Triazole ERRα Inverse Agonists

Estrogen-related receptor α (ERRα), which is overexpressed in a variety of cancers has been considered as an effective target for anticancer therapy. ERRα inverse agonists have been proven to effectively inhibit the migration and invasion of cancer cells. As few crystalline complexes have been reported, molecular dynamics (MD) simulations were carried out in this study to deepen the understanding of the interaction mechanism between inverse agonists and ERRα. The binding free energy was analyzed by the MM-GBSA method. The results show that the total binding free energy was positively correlated with the biological activity of an inverse agonist. The interaction of the inverse agonist with the hydrophobic interlayer composed of Phe328 and Phe495 had an important impact on the biological activity of inverse agonists, which was confirmed by the decomposition of energy on residues. As Glu331 flipped and formed a hydrogen bond with Arg372 in the MD simulation process, the formation of hydrogen bond interaction with Glu331 was not a necessary condition for the compound to act as an inverse agonist. These rules provide guidance for the design of new inverse agonists.

FBXL10 promotes ERRα protein stability and proliferation of breast cancer cells by enhancing the mono-ubiquitylation of ERRα

The underlying mechanism of orphan nuclear receptor estrogen-related receptor α (ERRα) in breast cancer was investigated by identifying its interaction partners using mass spectrometry. F-box and leucine-rich repeat protein 10 (FBXL10), which modulates various physiological processes, may interact with ERRα in breast cancer. Here, we investigated the interaction between FBXL10 and ERRα, and their protein expression and correlation in breast cancer. Mechanical studies revealed that FBXL10 stabilized ERRα protein levels by reducing its poly-ubiquitylation and promoting its mono-ubiquitylation. The reporter gene assay and examination of ERRα target genes validated the increased transcriptional activity of ERRα due to its increased protein levels by FBXL10. FBXL10 also increased ERRα enrichment at the promoter region of its target genes. Functionally, FBXL10 facilitated the ERRα/peroxisome proliferator-activated receptor gamma coactivator 1 β (PGC1β)-mediated proliferation and tumorigenesis of breast cancer cells in vitro and in vivo. Our results uncovered a molecular mechanism linking the mono-ubiquitylation and protein stability of ERRα to functional interaction with FBXL10. Moreover, a novel regulatory axis of FBXL10 and ERRα regulating the proliferation and tumorigenesis of breast cancer cells was established.

PGC-1α and ERRα in patients with endometrial cancer: a translational study for predicting myometrial invasion

BACKGROUND

PGC-1α and ERRα are closely related to tumor formation and progression. However, the mechanism underlying the involvement of PGC-1α/ERRα in regulating invasion and migration in endometrial cancer remains to be explored.

RESULTS

Elevated levels of PGC-1α and ERRα were associated with advanced myometrial invasion, and PGC-1α and Vimentin expression was related to the depth of myometrial invasion in premenopausal endometrial cancer. Silencing of PGC-1α reduced ERRα activation and inhibited epithelial-mesenchymal-transition phenotypes, resulting in significant inhibition of invasion and migration. Overexpression of ERRα led to enhanced PGC-1α expression and increased activity of TFEB, promoting epithelial-mesenchymal-transition in endometrial cancer cells.

CONCLUSIONS

PGC-1α and ERRα induce the epithelial-mesenchymal-transition therefore invasion and migration in endometrial cancer, and may be novel biomarkers to predict the risk of advanced myometrial invasion.

METHODS

PGC-1α, ERRα, and vimentin expression was analyzed in tissue microarrays using immunohistochemistry. PGC-1α and ERRα expression in endometrial cancer cell lines was investigated using quantitative PCR and western blotting analyses after infection with lentivirus-mediated small interfering RNA (siRNA) targeting PGC-1α (siRNA-PGC-1α) or overexpressing ERRα. E-cadherin and vimentin levels were determined using western blotting and cell immunouorescence analyses. Cell migration and invasiveness were evaluated using scratch and trans-well chamber assays.

Isolation and functional characterization of a novel endogenous inverse agonist of estrogen related receptors (ERRs) from human pregnancy urine

Estrogen-receptor related receptors (ERRs) which consists of ERRα, ERRβ and ERRγ belong to the orphan nuclear receptor subfamily 3, group B (NR3B) subfamily, and are constitutively active. ERRs have been shown to actively modulate estrogenic responses, and to play an essential role in pregnancy, and are implicated in breast cancer progression. Despite intensive efforts, no endogenous ligand other than the ubiquitous sterol, cholesterol which binds ERRα, has been identified for ERRs so far. The discovery of ligands that bind these orphan receptors will allow the manipulation of this pathway and may lead to novel strategies for the treatment of cancer and other diseases. We previously reported the identification of a novel endogenous estradienolone-like steroid (ED) that is strongly bound to sex hormone binding globulin, in pregnant women. Our recent results show that ED acts as an inverse agonist of ERRα and ERRγ by directly interacting with these receptors, and inhibiting their transcriptional activity. We also demonstrate that ED inhibits the growth of both estrogen receptor-positive (MCF-7) and estrogen receptor-negative (MDA-MB-231) breast cancer cells in a dose dependent manner, while of displaying a little effect on normal epithelial breast cells. Furthermore, the anti-mitogenic effect of ED in breast cancer cells is ERRα-dependent. These data suggest that ED-ERR interaction may represent a novel physiologically relevant hormone response pathway in the human. The finding that ED inhibits both ER negative and ER positive breast cancer cell growth may have important implications in pathophysiology breast cancer.

Identification of New Small-Molecule Inducers of Estrogen-related Receptor α (ERRα) Degradation

A series of (E)-3-(4-((2,4-bis(trifluoromethyl)benzyl)oxy)-3-methoxyphenyl)-2-cyanoacrylamide derivatives were designed and synthesized as new estrogen-related receptor α (ERRα) degraders based on the proteolysis targeting chimera (PROTAC) concept. One of the representative compounds 6c is capable of specifically degrading ERRα protein by >80% at a relatively low concentration of 30 nM, becoming one of the most potent and selective ERRα degraders to date. Compound 6c could be utilized as a new powerful research tool for further biological investigation of ERRα.

Key regulator of cellular metabolism, estrogen-related receptor α, a new therapeutic target in endocrine-related gynecological tumor

The estrogen-related receptor α (ERRα), is an orphan transcription factor. Recently, many studies have reported its regulatory mechanisms and transcriptional targets after identification. Therefore, it may be eligible to join the rank of other nuclear receptors that control almost all aspects of cell metabolism. Cellular metabolism reprogramming plays a key role in fueling malignant change. The purpose of this review was to demonstrate that the ERRα plays an important role in the association between gynecological endocrine-related tumors and energy metabolism. Furthermore, regulation of ERRα may represent a promising strategy to induce cellular metabolic vulnerability of cancer from different origins. Thus, a comprehensive understanding of current treatment strategies may be achieved.

Novel endocrine therapeutic strategy in endometrial carcinoma targeting estrogen-related receptor α by XCT790 and siRNA

Purpose

To explore the targeted therapy of estrogen-related receptor α (ERRα) in endometrial cancer (EC) cells and its potential mechanisms.

Methods

The mRNA and protein expression levels of ERRα and estrogen receptor α (ERα) were detected by qPCR and Western blotting in RL-952, AN3-CA, HEC-1A, and HEC-1B EC cell lines. After treatment with the ERRα-specific antagonist XCT790 or infection with lentivirus-mediated small interfering RNA (siRNA) targeting the ERRα (siRNA-ERRα), cell proliferation and apoptosis were evaluated by MTS assay and flow cytometry. After treatment with siRNA-ERRα, the expression profiles of transcription factors (TFs) were analyzed by protein/DNA arrays in EC cells.

Results

The relative mRNA levels of ERRa in RL-952 (1±0.0831) and AN3-CA (1.162±0.0325) were significantly higher than those in HEC-1A (0.3081±0.0339) and HEC-1B (0.1119±0.0091) (P<0.05), and similar results were observed for ERRα protein levels. A higher ratio of ERa/ERRa was observed in ERα-positive RL-952 (10-fold) and ANC-3A (8.5-fold) cells, whereas a lower ratio was observed in ERα-negative HEC-1A (3.75-fold) and HEC-1B cells (0-fold). Both – exogenous XCT790 and endogenous siRNA-ERRα – can decrease the expression of ERRα, thereby inhibiting proliferation but promoting apoptosis in both ERα-positive and -negative EC cells. The XCT790 presented higher proliferation-inhibition and apoptosis rates in the ERα-positive than ERα-negative cells, whereas the siRNA-ERRα exhibited higher proliferation-inhibition and apoptosis rates in the ERα-negative than in ERα-positive cells. In total, 3 upregulated and 17 downregulated TFs were screened out by knocked-down expression of ERRα in all EC cells. Among them, the upregulated TFs organic cation transporter 3/4(Oct3/4), hepatic nuclear factor 4 (HNF4), HNF4 and chicken ovalbumin upstream TF (COUP-TF) as well as downregulated transcription factor EB (TFEB) were found to be statistically significant (P<0.05).

Conclusion

Targeting ERRα provides a promising novel endocrine therapeutic strategy.

Identification of Estrogen Receptor α Antagonists from Natural Products via In Vitro and In Silico Approaches

Estrogen receptor α (ERα) is a successful target for ER-positive breast cancer and also reported to be relevant in many other diseases. Selective estrogen receptor modulators (SERMs) make a good therapeutic effect in clinic. Because of the drug resistance and side effects of current SERMs, the discovery of new SERMs is given more and more attention. Virtual screening is a validated method to high effectively to identify novel bioactive small molecules. Ligand-based machine learning methods and structure-based molecular docking were first performed for identification of ERα antagonist from in-house natural product library. Naive Bayesian and recursive partitioning models with two kinds of descriptors were built and validated based on training set, test set, and external test set and then were utilized for distinction of active and inactive compounds. Totally, 162 compounds were predicted as ER antagonists and were further evaluated by molecular docking. According to docking score, we selected 8 representative compounds for both ERα competitor assay and luciferase reporter gene assay. Genistein, daidzein, phloretin, ellagic acid, ursolic acid, (-)-epigallocatechin-3-gallate, kaempferol, and naringenin exhibited different levels for antagonistic activity against ERα. These studies validated the feasibility of machine learning methods for predicting bioactivities of ligands and provided better insight into the natural products acting as estrogen receptor modulator, which are important lead compounds for future new drug design.

DT-13 synergistically potentiates the sensitivity of gastric cancer cells to topotecan via cell cycle arrest in vitro and in vivo

Natural medicine has multi-levels, multi-paths and multi-targets, and an increasing number of reports have confirmed that the combination of natural medicine with chemotherapy drugs exhibit a significant synergistic effect. It is necessary to find drug combination strategies to enhance efficacy and reduce toxicity, which can relieve the restrictions on the use of several chemotherapy drugs that have serious toxicity. Our previous reports showed that DT-13 inhibits cancer proliferation, invasion, migration, metastasis, and angiogenesis and induces autophagy. In this study, we evaluated the anti-proliferation effect of DT-13 on a panel of 40 different cancer cell lines for the first time. Moreover, it is also the first time that the combination of DT-13 with 5 different chemotherapy drugs on 3 common cancer cells has been examined. We further confirmed that DT-13 enhanced the sensitivity of gastric cancer cells to topotecan (TPT) via cell cycle arrest in vitro and in vivo. Considering that TPT has been subjected to restriction because of its serious toxicity, DT-13 showed the ability to enhance its effect and reduce its toxicity, which could provide a strategy to reduce the toxic and clinical side effects of TPT.

A novel compound LingH2-10 inhibits the growth of triple negative breast cancer cells in vitro and in vivo as a selective inverse agonist of estrogen-related receptor α

Unlike other breast cancer subtypes, targeted therapies for triple negative breast cancer (TNBC) have yet to progress past clinical trial stage to approval. Accumulating evidences demonstrated that expression of estrogen-related receptor alpha (ERRα) indicated worse prognosis and correlated with poor outcome in breast cancers including TNBC. Therefore, ERRα modulators/regulators may be potential in the therapeutic treatment of breast cancers. In the current study, we presented a novel compound LingH2-10 that bound to ERRα, as identified using a time-resolved fluorescence resonance energy transfer assay (TR-FRET) with the IC50 value of 0.64±0.12μM. Further, functional activity was determined by transient transfection luciferase reporter assay in order to validate the utility of the binding affinity in a cellular context. LingH2-10 showed selective inhibition on ERRα transcriptional activity with the IC50 value of 0.58±0.09μM in cell-based luciferase reporter assay. Moreover, representative in vitro results showed that LingH2-10 suppressed the proliferation of various human cancer cells, and inhibited the migration of triple negative breast cancer cell MDA-MB-231. In addition, our results demonstrated that well known ERRα target genes such as PDK4, Osteopontin and pS2, were all significantly down modulated by LingH2-10. In vivo experiments showed that LingH2-10 (30mg/kg, every other day) observably suppressed the growth of MDA-MB-231 xenograft tumors by 42.02% compared to untreated xenograft tumors. Taken together, all these data suggested that LingH2-10, as a selective inverse agonist of ERRα, was a lead compound of anti-cancer agents for treating TNBC patients.

The discovery of novel, potent ERR-alpha inverse agonists for the treatment of triple negative breast cancer

The estrogen-related receptor α (ERRα) is an orphan receptor and a novel target for solid tumor therapy, conceivably through effects on the regulation of tumor cell energy metabolism associated with energy stress within solid tumor micro environments. Here we describe the discovery of novel potent inverse agonists of ERRα. In vitro, compound 11 potently inhibits ERRα's transcriptional activity by preventing endogenous PGC-1α and ERRα binding and suppresses the proliferation of different human cancer cell lines and the migration of breast cancer cells (MDA-MB-231). In vivo, compound 11 demonstrates a strong inhibitory effect on the growth of human breast cancer xenografts (MDA-MB-231) and the tumor growth is inhibited by 40.9% after treating with compound 11 (30 mg/kg). The binding mode shows that compound 11 interacts with the binding pocket of ERRα through hydrogen interactions with the residue Gly397 and hydrophobic interactions with the hydrophobic residues. All these results suggest that compound 11 represents a novel potent ERRα inverse agonist and is promising in the discovery of antitumor compounds for the treatment of triple negative breast cancer.