ERβ alters the chemosensitivity of luminal breast cancer cells by regulating p53 function

Anticancer or carcinogenic? The role of estrogen receptor β in breast cancer progression

Estrogen receptor β (ERβ) is closely related to breast cancer (BC) progression. Traditional concepts regard ERβ as a tumor suppressor. As studies show the carcinogenic effect of ERβ, some people have come to a new conclusion that ERβ serves as a tumor suppressor in estrogen receptor α (ERα)-positive breast cancer, while it is a carcinogen in ERα-negative breast cancer. However, we re-examine the role of ERβ and find this conclusion to be misleading based on the last decade's research. A large number of studies have shown that ERβ plays an anticancer role in both ERα-positive and ERα-negative breast cancers, and its carcinogenicity does not depend solely on the presence of ERα. Herein, we review the anticancer and oncogenic effects of ERβ on breast cancer progression in the past ten years, discuss the mechanism respectively, analyze the main reasons for the inconsistency and update ERβ selective ligand library. We believe a detailed and continuously updated review will help correct the one-sided understanding of ERβ, promoting ERβ-targeted breast cancer therapy.

In Vitro Evaluation of the Antioxidant Activity and Chemopreventive Potential in Human Breast Cancer Cell Lines of the Standardized Extract Obtained from the Aerial Parts of Zigzag Clover (Trifolium medium L.)

The aboveground parts of Trifolium medium L. (zigzag clover), a little-known representative of the family Fabaceae, collected during flowering in a wild stand (Sławin-Szerokie district, Lublin, Poland), were used in this study. Our previous investigations confirmed the higher content of phytoestrogenic isoflavones (especially biochanin A and formononetin derivatives) in T. medium compared to the closely related medicinal plant T. pratense (red clover) and the involvement of these compounds in anti-osteoporotic effects in ovariectomized female rats. The current study focused on evaluating other antibiodegenerative (antioxidant, chemopreventive, and cytostatic) effects for the lyophilisate (TML) obtained from wild zigzag clover. For this purpose, efficient ultrasound-assisted extraction (UAE) was employed, followed by vacuum drying and phytochemical standardization using a newly developed reversed-phase high-performance liquid chromatography (RP-LC) coupled with a PDA detection. Malonylglycosides of biochanin A and formononetin were the predominant compounds and were found to contribute more than 54% to the total isoflavone content determined in the standardized extract of zigzag clover. The antioxidant potential of TML was examined in vitro using the Folin–Ciocalteu and cupric ion-reducing (CUPRAC) methods in addition to the free radical (DPPH• and ABTS•+) scavenging assays. The cytotoxic effects of TML, formononetin, and ononin were evaluated on MCF-7 (estrogen-dependent) and MDA-MB-231 (estrogen-independent) human breast cancer cell lines using the MTT assay. The important role of malonyl isoflavone derivatives has been indicated both in chemoprevention and potential cytotoxic effects of TML against certain types of breast cancer.

The expression and clinical significance of ERβ/ERα in ovarian cancer: can we predict the effectiveness of platinum plus taxane therapy?

Estrogens play an extremely important role in regulating the proliferation of ovarian cancer. The estrogen receptor alpha (ERα) stimulates cell growth, whereas ERβ can be attributed to tumor suppressors. The study aims to assess the relationship between the expression of estrogen receptors in tumors and the efficacy of front-line platinum plus taxane chemotherapy in ovarian cancer patients.

MATERIALS AND METHODS

ERα and ERβ tumor expression was evaluated quantitatively by flow cytometry in a narrowly defined group (31 patients): stage III high-grade serous ovarian carcinoma (HGSOC), suboptimal surgical cytoreduction, front-line platinum plus taxane chemotherapy (front-line, six cycles).

RESULTS

The median of progression-free survival (PFS) was 2 times greater (18 vs 8 months, p = 0.04) and the recurrence risk (HR) was 2.2 times (95 % CI: 1.1-6.2, p = 0.04) lower in the group with high (in more than 40% of the cells) vs low level of ERβ tumor expression. The statistically significant difference between PFS in the groups with high vs low tumor ERα expression was not revealed.

CONCLUSION

A high level of ERβ and not ERα expression can predict the efficacy of front-line platinum plus taxane chemotherapy in stage III HGSOC patients. The status of estrogen receptor beta can be considered as one of the possible predictors for evaluating the effectiveness of ovarian cancer therapy.

Estrogen Receptor β-Mediated Inhibition of Actin-Based Cell Migration Suppresses Metastasis of Inflammatory Breast Cancer

Inflammatory breast cancer (IBC) is a highly metastatic breast carcinoma with high frequency of estrogen receptor α (ERα) negativity. Here we explored the role of the second ER subtype, ERβ, and report expression in IBC tumors and its correlation with reduced metastasis. Ablation of ERβ in IBC cells promoted cell migration and activated gene networks that control actin reorganization, including G-protein-coupled receptors and downstream effectors that activate Rho GTPases. Analysis of preclinical mouse models of IBC revealed decreased metastasis of IBC tumors when ERβ was expressed or activated by chemical agonists. Our findings support a tumor-suppressive role of ERβ by demonstrating the ability of the receptor to inhibit dissemination of IBC cells and prevent metastasis. On the basis of these findings, we propose ERβ as a potentially novel biomarker and therapeutic target that can inhibit IBC metastasis and reduce its associated mortality. SIGNIFICANCE: These findings demonstrate the capacity of ERβ to elicit antimetastatic effects in highly aggressive inflammatory breast cancer and propose ERβ and the identified associated genes as potential therapeutic targets in this disease.

Histone deacetylase inhibitors enhance estrogen receptor beta expression and augment agonist-mediated tumor suppression in glioblastoma

BACKGROUND

Glioblastomas (GBMs) are the most lethal primary brain tumors. Estrogen receptor β (ESR2/ERβ) function as a tumor suppressor in GBM, however, ERβ expression is commonly suppressed during glioma progression. In this study, we examined whether drugs that reverse epigenetic modifications will enhance ERβ expression and augment ERβ agonist-mediated tumor suppression.

METHODS

We tested the utility of epigenetic drugs which act as an inhibitor of histone deacetylases (HDACs), histone methylases, and BET enzymes. Mechanistic studies utilized RT-qPCR, chromatin immunoprecipitation (ChIP), and western blotting. Cell viability, apoptosis, colony formation, and invasion were measured using in vitro assays. An orthotopic GBM model was used to test the efficacy of in vivo.

RESULTS

Of all inhibitors tested, HDACi (panobinostat and romidepsin) showed the potential to increase the expression of ERβ in GBM cells. Treatment with HDACi uniquely upregulated ERβ isoform 1 expression that functions as a tumor suppressor but not ERβ isoform 5 that drives oncogenic functions. Further, combination therapy of HDACi with the ERβ agonist, LY500307, potently reduced cell viability, invasion, colony formation, and enhanced apoptosis. Mechanistic studies showed that HDACi induced ERβ is functional, as it enhanced ERβ reporter activities and ERβ target genes expression. ChIP analysis confirmed alterations in the histone acetylation at the ERβ and its target gene promoters. In orthotopic GBM model, combination therapy of panobinostat and LY500307 enhanced survival of tumor-bearing mice.

CONCLUSIONS

Our results suggest that the combination therapy of HDACi and LY500307 provides therapeutic utility in overcoming the suppression of ERβ expression that commonly occurs in GBM progression.

The role of estrogen receptor beta in breast cancer

Breast cancer, a malignant tumor originating from mammary epithelial tissue, is the most common cancer among women worldwide. Challenges facing the diagnosis and treatment of breast cancer necessitate the search for new mechanisms and drugs to improve outcomes. Estrogen receptor (ER) is considered to be important for determining the diagnosis and treatment strategy. The discovery of the second estrogen receptor, ERβ, provides an opportunity to understand estrogen action. The emergence of ERβ can be traced back to 1996. Over the past 20 years, an increasing body of evidence has implicated the vital effect of ERβ in breast cancer. Although there is controversy among scholars, ERβ is generally thought to have antiproliferative effects in disease progression. This review summarizes available evidence regarding the involvement of ERβ in the clinical treatment and prognosis of breast cancer and describes signaling pathways associated with ERβ. We hope to highlight the potential of ERβ as a therapeutic target.

Moonlight human ribosomal protein L13a downregulation is associated with p53 and HER2/neu expression in breast cancer

Breast cancer is the most common malignancy among females worldwide. Recent studies have shown extra-ribosomal roles of the moonlight ribosomal proteins in the development of human cancers. Accurate quantification of the gene expression level is based on the selection of the reference genes whose expression is independent of cancer properties and patient's characteristics. The aim of this study was the evaluation of the expression level of a previously proposed ribosomal protein as moonlight, L13a (RPL13A), in breast cancer samples and their adjacent tissues. Its association with genes of known roles in developing cancers was also investigated. Traditionally used housekeeping genes were selected and their expression was analyzed in 80 surgically excised breast tissue specimens (40 tumors and 40 tumor-adjacent tissues) by applying three software tools including GeNorm, NormFinder, and BestKeeper to select the most stable reference genes. Then, mRNA expression levels of RPL13A and p53 were evaluated. Additionally, protein expression levels of RPL13A were measured. It was demonstrated that PUM1 and ACTB are the most reliable reference genes and RPL13A is the least stable gene. There was a positive correlation between RPL13A and p53 mRNA expression levels in all the tumor samples. Moreover, significant downregulation of RPL13A expression levels was revealed in HER2+ tumor samples compared to HER2- ones. There was also a marked decrease in p53 mRNA expression levels in HER2+ tumor subtypes. Our results suggest that there is a probable relationship between RPL13A decreased expression with p53 and HER2/neu expression in the breast cancer.

Overexpression Of ERβ Participates In The Progression Of Liver Cancer Via Inhibiting The Notch Signaling Pathway

PURPOSE

This study aimed to explore the role of Estrogen Receptor-β (ERβ)-mediated Notch signaling pathway in the regulation of proliferation and apoptosis in liver cancer cells.

METHODS

HepG2 cells (Pbi-EGFP-ER) were transfected with ERβ that mediated by liposome, and normal HepG2 cells (Blank) and empty plasmid-transfected HepG2 cells (Pbi-EGFP-C) were used as controls. Then, Huh7 cells were transfected with shERβ lentivirus to knock down ERβ expression. The Huh7 cells were divided into three groups including Blank, experimental group (shERβ) and negative group (shLuc). Then, qRT-PCR, Western blot, CCK-8 assay, cell scratch assay, Transwell assay, Annexin V-FITC and PI double staining were performed based on these groups. Finally, a mouse xenograft model was constructed to verify the regulation of ERβ on Notch signaling pathway in liver cancer.

RESULTS

In HepG2 cells, the ERβ expression in Pbi-EGFP-E group was higher than that in Blank and Bi-EGFP-C group. Overexpression of ERβ inhibited HepG2 cell proliferation, migration, invasion and Ki67 protein expression, as well as promoted apoptosis, Bcl-2 and Bax expression. Overexpression of ERβ decreased Notch1, Notch2 and Hes1 expression. In Huh7 cells, the effect of low ERβ expression was contrary to that of high ERβ expression. The shERβ + DAPT group reversed the effect of shERβ on the volume and weight of transplanted tumors.

CONCLUSION

ERβ may inhibit the development of liver cancer and promote apoptosis via inhibiting the Notch pathway.

Optimized immunohistochemical detection of estrogen receptor beta using two validated monoclonal antibodies confirms its expression in normal and malignant breast tissues

PURPOSE

Significant controversy exists regarding the expression patterns of estrogen receptor beta (ERβ) in normal and diseased breast tissue. To address this issue, we have validated two ERβ antibodies, optimized the IHC protocols for both antibodies and now report the expression patterns of ERβ in normal and malignant breast tissues.

METHODS

ERβ antibody specificity was determined using western blot and IHC analysis. ERβ protein expression patterns were assessed via IHC in normal breast tissue and invasive breast carcinoma. Further, we report the detailed protocol of the ERβ IHC assay developed in our CAP/CLIA certified laboratory to provide a standardized method for future studies.

RESULTS

We have confirmed the specificity of two independent ERβ monoclonal antibodies, one that detects total (i.e., full length plus splice variants 2-5, which do not include the ligand binding domain) ERβ protein (PPZ0506) and one that detects only the full-length form, which includes the ligand binding domain, of ERβ (PPG5/10). Using these two antibodies, we demonstrate that ERβ is highly expressed in normal human breast tissue as well as in 20-30% of invasive breast cancers. Further, these two antibodies exhibited similar staining patterns across multiple different tissues and were highly concordant with regard to determining ERβ positivity in breast cancers.

CONCLUSIONS

ERβ protein was shown to be abundant in the majority of normal breast epithelial cells and is present in 20-30% of breast cancers. Use of these two antibodies, along with their standardized IHC protocols, provide a reference for future studies aimed at determining the utility of ERβ as a prognostic and/or predictive biomarker in various tissues of benign or malignant states.

Characteristics, behaviour and role of biomarkers in metastatic triple-negative breast cancer

AIMS

Characterising the factors responsible for metastatic triple-negative breast cancer (TNBC) is of significant importance, considering its high mortality rate and scant data. In this study, we evaluated the characteristics, clinical behaviour and role of biomarkers (androgen receptor (AR), oestrogen receptor beta (ERβ) and p53) in metastatic TNBC.

METHODS

Immunohistochemistry was performed for AR, ERβ and p53 on 125 primary TNBCs with known metastasis and correlated with clinicopathological parameters and outcome. AR and p53 mRNA profiling was also carried out on 34 tumours from the same series and correlated with outcomes.

RESULTS

In this cohort, grade 3 and pT2 tumours predominated. The most common site for metastasis was the lung and pleura (41, 32.8%), and 15 (12.0%) cases demonstrated metastasis in multiple sites. Among these, 92% of tumours metastasised without preceding local recurrences. Five- and ten-year overall survival (OS) rates were 27% and 7.2%, while 5- and 10- year survival rates after metastasis were 9.6% and 3.2% respectively. AR, ERβ and p53 protein expressions were observed in 16%, 96.8% and 58.1% of tumours, respectively. A combinational phenotype of AR-ERβ+p53+ tumours was associated with poorer OS (HR 1.543, 95%CI 1.030 to 2.310, p=0.035). Higher AR mRNA levels were significantly associated with favourable OS (p=0.015) and survival after metastasis (p=0.027).

CONCLUSIONS

Metastatic TNBC harboured aggressive behaviour and displayed predominantly visceral metastasis with most metastatic events occurring without intervening local recurrences. A combinational phenotype of AR-ERβ+p53+ was significantly associated with poorer OS.

Estrogen receptor beta enhances chemotherapy response of GBM cells by down regulating DNA damage response pathways

Glioblastoma (GBM) is the most commonly diagnosed brain tumor that exhibit high mortality rate and chemotherapy resistance is a major clinical problem. Recent studies suggest that estrogen receptor beta (ERβ), may function as a tumor suppressor in GBM. However, the mechanism(s) by which ERβ contributes to GBM suppression and chemotherapy response remains unknown. We examined the role of ERβ in the DNA damage response of GBM cells, and tested whether ERβ sensitizes GBM cells to chemotherapy. Cell viability and survival assays using multiple epitope tagged ERβ expressing established and primary GBM cells demonstrated that ERβ sensitizes GBM cells to DNA damaging agents including temozolomide (TMZ). RNA-seq studies using ERβ overexpression models revealed downregulation of number of genes involved in DNA recombination and repair, ATM signaling and cell cycle check point control. Gene set enrichment analysis (GSEA) suggested that ERβ–modulated genes were correlated negatively with homologous recombination, mismatch repair and G2M checkpoint genes. Further, RT-qPCR analysis revealed that chemotherapy induced activation of cell cycle arrest and apoptosis genes were attenuated in ERβKO cells. Additionally, ERβ overexpressing cells had a higher number of γH2AX foci following TMZ treatment. Mechanistic studies showed that ERβ plays an important role in homologous recombination (HR) mediated repair and ERβ reduced expression and activation of ATM upon DNA damage. More importantly, GBM cells expressing ERβ had increased survival when compared to control GBM cells in orthotopic GBM models. ERβ overexpression further enhanced the survival of mice to TMZ therapy in both TMZ sensitive and TMZ resistant GBM models. Additionally, IHC analysis revealed that ERβ tumors had increased expression of γH2AX and cleaved caspase-3. Using ERβ-overexpression and ERβ-KO GBM model cells, we have provided the evidence that ERβ is required for optimal chemotherapy induced DNA damage response and apoptosis in GBM cells.

Good Guy or Bad Guy? The Duality of Wild-Type p53 in Hormone-Dependent Breast Cancer Origin, Treatment, and Recurrence

"Lactation is at one point perilously near becoming a cancerous process if it is at all arrested", Beatson, 1896. Most breast cancers arise from the milk-producing cells that are characterized by aberrant cellular, molecular, and epigenetic translation. By understanding the underlying molecular disruptions leading to the origin of cancer, we might be able to design novel strategies for more efficacious treatments or, ambitiously, divert the cancerous process. It is an established reality that full-term pregnancy in a young woman provides a lifetime reduction in breast cancer risk, whereas delay in full-term pregnancy increases short-term breast cancer risk and the probability of latent breast cancer development. Hormonal activation of the p53 protein (encode by the TP53 gene) in the mammary gland at a critical time in pregnancy has been identified as one of the most important determinants of whether the mammary gland develops latent breast cancer. This review discusses what is known about the protective influence of female hormones in young parous women, with a specific focus on the opportune role of wild-type p53 reprogramming in mammary cell differentiation. The importance of p53 as a protector or perpetrator in hormone-dependent breast cancer, resistance to treatment, and recurrence is also explored.