Derailed estrogen signaling and breast cancer: an authentic couple

A Systematic Review and Meta-Analysis of the Effects of Dietary Isoflavones on Female Hormone-Dependent Cancers for Benefit-Risk Evaluation

Female hormone-dependent cancers depend on estrogen for their growth. Numerous studies have explored the antitumor effect of dietary isoflavones on female hormone-dependent cancers. Still, few clinical evidence supports the use of isoflavones in female hormone-dependent cancer patients. This study was performed to examine the impact of dietary isoflavones on tumor growth of female hormone-dependent cancers and accelerate the transformation of research from bench to bedside. We searched PubMed Medline, Web of Science, and Google Scholar for relevant articles related to the effect of dietary isoflavone on tumor growth of experimental animal models of female hormone-dependent cancers from 1998 to 2024. The effects of dietary isoflavones on tumor growth were analyzed between the control and treatment groups using comprehensive meta-analysis software (CMA). We included 30 studies describing tumor growth focused on female hormone-dependent cancer types, including breast, ovarian, and uterine cancers. Overall, a pooled analysis revealed that dietary isoflavones reduced tumor volume (Hedge's g = -1.151, 95% CI = -1.717 to -0.585, p = 0.000) and tumor weight (Hedge's g = -2.584, 95% CI = -3.618 to -1.549, p = 0.000). On the other hand, dietary isoflavones increased tumor area (Hedge's g = 1.136, 95% CI = 0.752 to 1.520, p = 0.000). Dietary isoflavones have potential benefits and risks in female hormone-dependent cancers. Therefore, caution should be exercised when considering the intake of dietary isoflavones in female hormone-dependent cancer patients, particularly in the form of supplements.

METTL14-mediated m6A modification enhances USP22-ERα axis to drive breast cancer malignancy

The abundance and activity of estrogen receptor alpha (ERα) are tightly regulated by ubiquitin-specific peptidase 22 (USP22) during the progression of breast cancer (BCa). However, the post-transcriptional modifications on the USP22-ERα axis remain elusive. N6-methyladenosine (m6A) is critical to modulate RNA status in eukaryotic cells. Here, we find that METTL14 positively regulates the mRNA expression of USP22 and ERα. Mechanistically, METTL14 potently binds to the USP22 and ERα mRNA, and thereby enhancing their stability through m6A modification. YTHDC1 and YTHDF1 function as readers for m6A-modified USP22 and ERα, respectively. Additionally, METTL14 promotes the growth and migration of ERα+ BCa via the USP22-ERα-Cyclin D1 axis. Enforced expression of USP22/ERα significantly reverses the METTL14 depletion-induced growth and migration inhibition in BCa. Moreover, our analysis of clinical samples shows that the expression of METTL14, USP22, and ERα is upregulated and correlated in BCa tissues. Overall, our findings reveal the key role of the METTL14-USP22-ERα axis in BCa progression, which further provides a druggable target to treat BCa.

MicroRNA signature of stromal-epithelial interactions in prostate and breast cancers

Stromal-epithelial communication is an absolute necessity when it comes to the morphogenesis and pathogenesis of solid tissues, including the prostate and breast. So far, signalling pathways of several growth factors have been investigated. Besides such chemical factors, non-coding RNAs such as miRNAs have recently gained much interest because of their variety and complexity of action. Prostate and breast tissues being highly responsive to steroid hormones such as androgen and estrogen, respectively, it is not surprising that a huge set of available literature critically investigated the interplay between such hormones and miRNAs, especially in carcinogenesis. This review showcases our effort to highlight hormonally-related miRNAs that also somehow perturb the regular stromal-epithelial interactions during carcinogenesis in the prostate and breast. In future, we look forward to exploring how hormonal changes in the tissue microenvironment bring about miRNA-mediated changes in stromal-epithelial interactome in carcinogenesis and cancer progression.

Interrogating Estrogen Signaling Pathways in Human ER-Positive Breast Cancer Cells Forming Bone Metastases in Mice

Breast cancer bone metastases (BMET) are incurable, primarily osteolytic, and occur most commonly in estrogen receptor-α positive (ER+) breast cancer. ER+ human breast cancer BMET modeling in mice has demonstrated an estrogen (E2)-dependent increase in tumor-associated osteolysis and bone-resorbing osteoclasts, independent of estrogenic effects on tumor proliferation or bone turnover, suggesting a possible mechanistic link between tumoral ERα-driven osteolysis and ER+ bone progression. To explore this question, inducible secretion of the osteolytic factor, parathyroid hormone-related protein (PTHrP), was utilized as an in vitro screening bioassay to query the osteolytic potential of estrogen receptor- and signaling pathway-specific ligands in BMET-forming ER+ human breast cancer cells expressing ERα, ERß, and G protein-coupled ER. After identifying genomic ERα signaling, also responsibility for estrogen's proliferative effects, as necessary and sufficient for osteolytic PTHrP secretion, in vivo effects of a genomic-only ER agonist, estetrol (E4), on osteolytic ER+ BMET progression were examined. Surprisingly, while pharmacologic effects of E4 on estrogen-dependent tissues, including bone, were evident, E4 did not support osteolytic BMET progression (vs robust E2 effects), suggesting an important role for nongenomic ER signaling in ER+ metastatic progression at this site. Because bone effects of E4 did not completely recapitulate those of E2, the relative importance of nongenomic ER signaling in tumor vs bone cannot be ascertained here. Nonetheless, these intriguing findings suggest that targeted manipulation of estrogen signaling to mitigate ER+ metastatic progression in bone may require a nuanced approach, considering genomic and nongenomic effects of ER signaling on both sides of the tumor/bone interface.

Endocrine Disruptors and Metabolic Changes: Impact on Puberty Control

OBJECTIVE

This study aims to explore the significant impact of environmental chemicals on disease development, focusing on their role in developing metabolic and endocrine diseases. The objective is to understand how these chemicals contribute to the increasing prevalence of precocious puberty, considering various factors, including epigenetic changes, lifestyle, and emotional disturbances.

METHODS

The study employs a comprehensive review of descriptive observational studies in both human and animal models to identify a degree of causality between exposure to environmental chemicals and disease development, specifically focusing on endocrine disruption. Due to ethical constraints, direct causation studies in human subjects are not feasible; therefore, the research relies on accumulated observational data.

RESULTS

Puberty is a crucial life period with marked physiological and psychological changes. The age at which sexual characteristics develop is changing in many regions. The findings indicate a correlation between exposure to endocrine-disrupting chemicals and the early onset of puberty. These chemicals have been shown to interfere with normal hormonal processes, particularly during critical developmental stages such as adolescence. The research also highlights the interaction of these chemical exposures with other factors, including nutritional history, social and lifestyle changes, and emotional stress, which together contribute to the prevalence of precocious puberty.

CONCLUSION

Environmental chemicals significantly contribute to the development of certain metabolic and endocrine diseases, particularly in the rising incidence of precocious puberty. Although the evidence is mainly observational, it adequately justifies regulatory actions to reduce exposure risks. Furthermore, these findings highlight the urgent need for more research on the epigenetic effects of these chemicals and their wider impact on human health, especially during vital developmental periods.

Reviewing the significance of dendritic cell vaccines in interrupting breast cancer development

Breast cancer is a heterogeneous disease and is the most prevalent cancer in women. According to the U.S breast cancer statistics, about 1 in every 8 women develop an invasive form of breast cancer during their lifetime. Immunotherapy has been a significant advancement in the treatment of cancer with multiple studies reporting favourable patient outcomes by modulating the immune response to cancer cells. Here, we review the significance of dendritic cell vaccines in treating breast cancer patients. We discuss the involvement of dendritic cells and oncodrivers in breast tumorigenesis, highlighting the rationale for targeting oncodrivers and neoantigens using dendritic cell vaccine therapy. We review different dendritic cell subsets and maturation states previously used to develop vaccines and suggest the use of DC vaccines for breast cancer prevention. Further, we highlight that the intratumoral delivery of type 1 dendritic cell vaccines in breast cancer patients activates tumor antigen-specific CD4+ T helper cell type 1 (Th1) cells, promoting an anti-tumorigenic immune response while concurrently blocking pro-tumorigenic responses. In summary, this review provides an overview of the current state of dendritic cell vaccines in breast cancer highlighting the challenges and considerations necessary for an efficient dendritic cell vaccine design in interrupting breast cancer development.

PSMD14 stabilizes estrogen signaling and facilitates breast cancer progression via deubiquitinating ERα

The over-activation of ERα signaling is regarded as the major driver for luminal breast cancers, which could be effective controlled via selective estrogen receptor modulators (SERM), such as tamoxifen. The endocrine resistance is still a challenge for breast cancer treatment, while recently studies implicate the post-translational modification on ERα play important roles in endocrine resistance. The stability of ERα protein and ERα transcriptome are subject to a balance between E3 ubiquitin ligases and deubiquitinases. Through deubiquitinases siRNA library screening, we discover PSMD14 as a critical deubiquitinase for ERα signaling and breast cancer progression. PSMD14 could facilitate breast cancer progression through ERα signaling in vitro and in vivo, while pharmaceutical inhibition of PSMD14 via Thiolutin could block the tumorigenesis in breast cancer. In endocrine resistant models, PSMD14 inhibition could de-stabilize the resistant form of ERα (Y537S) and restore tamoxifen sensitivity. Molecular studies reveal that PSMD14 could inhibition K48-linked poly-ubiquitination on ERα, facilitate ERα transcriptome. Interestingly, ChIP assay shows that ERα could bind to the promoter region of PSMD14 and facilitate its gene transcription, which indicates PSMD14 is both the upstream modulator and downstream target for ERα signaling in breast cancer. In general, we identified a novel positive feedback loop between PSMD14 and ERα signaling in breast cancer progression, while blockade of PSMD14 could be a plausible strategy for luminal breast cancer.

MYSM1 acts as a novel co-activator of ERα to confer antiestrogen resistance in breast cancer

Endocrine resistance is a crucial challenge in estrogen receptor alpha (ERα)-positive breast cancer (BCa). Aberrant alteration in modulation of E2/ERα signaling pathway has emerged as the putative contributor for endocrine resistance in BCa. Herein, we demonstrate that MYSM1 as a deubiquitinase participates in modulating ERα action via histone and non-histone deubiquitination. MYSM1 is involved in maintenance of ERα stability via ERα deubiquitination. MYSM1 regulates relevant histone modifications on cis regulatory elements of ERα-regulated genes, facilitating chromatin decondensation. MYSM1 is highly expressed in clinical BCa samples. MYSM1 depletion attenuates BCa-derived cell growth in xenograft models and increases the sensitivity of antiestrogen agents in BCa cells. A virtual screen shows that the small molecule Imatinib could potentially interact with catalytic MPN domain of MYSM1 to inhibit BCa cell growth via MYSM1-ERα axis. These findings clarify the molecular mechanism of MYSM1 as an epigenetic modifier in regulation of ERα action and provide a potential therapeutic target for endocrine resistance in BCa.

Gut microbiome influences incidence and outcomes of breast cancer by regulating levels and activity of steroid hormones in women

BACKGROUND

Breast cancer, the leading cancer type in women worldwide, is affected by reproductive and nonreproductive factors. Estrogen and progesterone influence the incidence and progression of breast cancer. The microbiome of the gut, a complex organ that plays a vital role in digestion and homeostasis, enhances availability of estrogen and progesterone in the host. Thus, an altered gut microbiome may influence the hormone-induced breast cancer incidence. This review describes the current understanding of the roles of gut microbiome in influencing the incidence and progression of breast cancer, with an emphasis on the microbiome-induced metabolism of estrogen and progesterone.

RECENT FINDINGS

Microbiome has been recognized as a promising hallmark of cancer. Next-generation sequencing technologies have aided in rapid identification of components of the gut microbiome that are capable of metabolizing estrogen and progesterone. Moreover, studies have indicated a wider role of the gut microbiome in metabolizing chemotherapeutic and hormonal therapy agents and reducing their efficacy in patients with breast cancer, with a predominant effect in postmenopausal women.

CONCLUSION

The gut microbiome and variations in its composition significantly alter the incidence and therapy outcomes of patients with breast cancer. Thus, a healthy and diverse microbiome is required for better response to anticancer therapies. Finally, the review emphasizes the requirement of studies to elucidate mechanisms that may aid in improving the gut microbiome composition, and hence, survival outcomes of patients with breast cancer.

circRNA-SFMBT2 orchestrates ERα activation to drive tamoxifen resistance in breast cancer cells

Dysregulated ERα signaling is responsible for endocrine resistance and eventual relapse in patients with estrogen receptor-positive (ER⁺) breast cancer. Thus, identifying novel ERα regulators is necessary to fully understand the mechanisms of endocrine resistance. Here, we identified circRNA-SFMBT2 to be highly expressed in ER⁺ breast cancer cells in comparison to ER^- cells and found that high circRNA-SFMBT2 levels were related to larger tumor size and poor prognosis in patients with ER⁺ breast cancer. In vitro and in vivo experiments confirmed that the circRNA-SFMBT2 level was positively correlated with the ERα protein level, implying a regulatory role for circRNA-SFMBT2 in ERα signaling. Moreover, we found that circRNA-SFMBT2 biogenesis could be facilitated via RNA-binding protein quaking (QKI), and biologically elevated circRNA-SFMBT2 expression promoted cell growth and tamoxifen resistance in ER⁺ breast cancer. Mechanistically, circRNA-SFMBT2 exhibits a specific tertiary structure that endows it with a high binding affinity for ERα and allows it to interact with the AF2 and DBD domains of ERα, enforcing recruitment of RNF181 to the AF1 domain of ERα. Furthermore, the circRNA-SFMBT2/RNF181 axis differentially regulated K48-linked and K63-linked ubiquitination of ERα to enhance ERα stability, resulting in increased expression of ERα target genes and tumor progression. In summary, circRNA-SFMBT2 is an important regulator of ERα signaling, and antagonizing circRNA-SFMBT2 expression may constitute a potential therapeutic strategy for breast cancer.

Sexual dysfunctions in breast cancer patients: evidence in context

INTRODUCTION

In breast cancer patients, endocrine therapy may exert a negative impact on sexual functioning in both genders, with potentially relevant consequences concerning quality of life and treatment adherence. The availability of effective interventions to maintain and/or restore sexual health in breast cancer patients is a key issue to a research agenda.

OBJECTIVES

To summarize and critically discuss the most updated and qualitatively relevant literature on the therapeutic approach to sexual impairment in breast cancer patients, with a focus on patients treated with endocrine therapy.

METHODS

We searched PubMed from its inception to February 2022 for observational and intervention trials including participants with sexual dysfunctions. We were particularly interested in studies of breast cancer patients with sexual dysfunctions while undergoing endocrine therapy. We developed a search strategy with the aim of maximizing the number of articles considered for screening and potential inclusion.

RESULTS

Forty-five studies were selected: 3 observational and 42 intervention studies. Thirty-five studies were exclusively focused on female breast cancer populations. We could not identify studies exclusively focused on or also including male breast cancer patients. Overall, in female patients, the available armamentarium encompasses vaginal lubricants, moisturizers, estrogens, dehydroepiandrosterone, CO2 laser, ospemifene, and counseling. None of these interventions has been demonstrated to completely solve sexual dysfunctions when singularly considered. More favorable outcomes have come from the combination of different therapies.

CONCLUSION

In female breast cancer, future research is oriented toward the gain of evidence on combined therapies and long-term data on safety issues on the most promising interventions. The lack of evidence on sexual disturbances in male breast cancer patients remains a major concern.

Design, synthesis, antiproliferative activity, estrogen receptors binding affinity of C-3 pregnenolone-dihydropyrimidine derivatives for the treatment of breast cancer

Breast cancer (BCa) is very common malignancy and globally, has become the second leading cause of cancer death among women. For the treatment of BCa, estrogen receptors-alpha (ERα) has proven to be a therapeutic target. In continuation of our previous reported dihydropyrimidine-based pregnenolone derivatives, we modified at C-3 hydroxyl group. Structural architecture of estrogen receptors (ER) with excellent ER binding affinity was used for modification. MTT assay was used to evaluate the synthesized steroidal analogs for their antiproliferative activities against ER-positive MCF-7, ER-negative MDA-MB-231 (ER^-) breast cancer cells and non-cancerous HEK-293 cells. Structure activity relationship (SAR) studies revealed that diethanolamine containing pregnenolone derivatives showed significant cytotoxicity against ER + MCF-7 and also showed good binding affinity with ERα and are relatively safe against HEK-293 cell model. Docking studies demonstrated that high binding affinity of diethanolamine analogs is due to their binding interaction with key amino acid residues present in the binding site of Erα.

Embryonic Programs in Cancer and Metastasis—Insights From the Mammary Gland

Cancer is characterized as a reversion of a differentiated cell to a primitive cell state that recapitulates, in many aspects, features of embryonic cells. This review explores the current knowledge of developmental mechanisms that are essential for embryonic mouse mammary gland development, with a particular focus on genes and signaling pathway components that are essential for the induction, morphogenesis, and lineage specification of the mammary gland. The roles of these same genes and signaling pathways in mammary gland or breast tumorigenesis and metastasis are then summarized. Strikingly, key embryonic developmental pathways are often reactivated or dysregulated during tumorigenesis and metastasis in processes such as aberrant proliferation, epithelial-to-mesenchymal transition (EMT), and stem cell potency which affects cellular lineage hierarchy. These observations are in line with findings from recent studies using lineage tracing as well as bulk- and single-cell transcriptomics that have uncovered features of embryonic cells in cancer and metastasis through the identification of cell types, cell states and characterisation of their dynamic changes. Given the many overlapping features and similarities of the molecular signatures of normal development and cancer, embryonic molecular signatures could be useful prognostic markers for cancer. In this way, the study of embryonic development will continue to complement the understanding of the mechanisms of cancer and aid in the discovery of novel therapeutic targets and strategies.

Network pharmacology-based study to identify the significant pathways of Lentinula edodes against cancer

Lentinula edodes (LE) is known as a good food source with potent anticancer efficacy, but its active chemical compounds and pathways against cancer have not been revealed. This study was to uncover the active chemical constituents and pathways of LE against cancer through network pharmacology. The chemical compositions were recognized by gas chromatography-mass spectrometry (GC-MS) and filtered drug-like compounds (DLCs) by SwissADME. Targets related to filtered compounds were recognized by two public databases and the final overlapping targets were identified by Venn diagram. Then, protein-protein interaction (PPI) and pathway-target-compound (PTC) networks were built by RStudio. Ultimately, we recognized the key compounds and targets via molecular docking test (MDT). A total of 33 compounds from LE were accepted by Lipinski's rule were selected as DLCs. The 33 compounds were associated with 108 targets and a key target (cyclooxygenase2 [COX2]) was identified through PPI networks. Most significantly, inactivation of pathways in cancer and activation of peroxisome proliferator activated receptor signaling pathway were significant pathways of LE. On MDT, we identified a key compound (Indole, 2-methyl-3-phenyl) on COX2 related to inactivation of athways in cancer, additionally, the number of 6 ergostane steroids was associated with the two pathways might be dual efficacy to alleviate inflammation against cancer. Overall, 13 targets, 11 compounds, and 2 key pathways of LE were identified as the significant elements to treat cancer. Hence, this study shows therapeutic evidence to verify the promising clinical effect of LE on cancer, suggesting that LE might be an important mushroom against cancer. PRACTICAL APPLICATIONS: Lentinula edodes (LE) has been used widely in cuisine as well as alternative medicines, especially, for anticancer. The LE has rich nutritional compounds including proteins, vitamins, polyphenols, and glucans, however, most of which have a critical hurdle as poor bioavailability not to be applicable for pharmaceuticals. Its main cause is very hydrophilic property. Thus, we adopted GC-MS analysis to identify lipophilic compounds to enhance cell permeability involved in bioavailability. The compounds selected from LE were confirmed by Lipinski's rule for drug-like-compounds (DLCs). Then, we retrieved targets associated with DLCs, and multiple pathways, multiple targets, and multiple compounds against cancer on network-based analysis. In summary, our study reveals the medicinal value of LE on cancer based on the multicomponents. Overall, the aim of this work is to represent the pharmacological evidence to reveal the therapeutic efficacy of AC on cancer, suggesting that DLCs from AC might be alleviators to dampen cancer.

A review on epidermal growth factor receptor's role in breast and non-small cell lung cancer

Epithelial growth factor receptor (EGFR) is a cell surface transmembrane receptor that mediates the tyrosine signaling pathway to carry the extracellular messages inside the cell and thereby alter the function of nucleus. This leads to the generation of various protein products to up or downregulate the cellular function. It is encoded by cell erythroblastosis virus oncogene B1, so called C-erb B1/ERBB2/HER-2 gene that acts as a proto-oncogene. It belongs to the HER-2 receptor-family in breast cancer and responds best with anti-Herceptin therapy (anti-tyrosine kinase monoclonal antibody). HER-2 positive breast cancer patient exhibits worse prognosis without Herceptin therapy. Similar incidence and prognosis are reported in other epithelial neoplasms like EGFR + lung non-small cell carcinoma and glioblastoma (grade IV brain glial tumor). Present study highlights the role and connectivity of EGF with various cancers via signaling pathways, cell surface receptors mechanism, macromolecules, mitochondrial genes and neoplasm. Present study describes the EGFR associated gene expression profiling (in breast cancer and NSCLC), relation between mitrochondrial genes and carcinoma, and several in vitro and in vivo models to screen the synergistic effect of various combination treatments. According to this study, although clinical studies including targeted treatments, immunotherapies, radiotherapy, TKi-EGFR combined targeted therapy have been carried out to investigate the synergism of combination therapy; however still there is a gap to apply the scenarios of experimental and clinical studies for further developments. This review will give an idea about the transition from experimental to most advanced clinical studies with different combination drug strategies to treat cancer.

Immunoprecipitation Analyses of Estrogen Receptor α Phosphorylated at Serine 216 in the Mouse Liver

Estrogen receptor α (ERα) conserves a phosphorylation motif at Serine 216. This site constitutes a protein kinase C phosphorylation motif located within the DNA binding domain (DBD) of ERα. The liver plays a critical role in the regulation of metabolism of various xenobiotics, fatty acids, and cholesterol or endogenous compounds. Moreover, numerous metabolizing enzymes are mainly expressed in the liver. In this chapter, we describe several practical experimental procedures confirming that mouse ERα is phosphorylated at serine 216 in livers upon phenobarbital (PB) treatment. Also, this phosphorylation regulates the expression of estrogen sulfotransferase gene (SULT1E1) which has an important role to sulfate and inactivate estrogen. In response to PB, the conserved motif within the DBD activates the Sult1e1 gene. When this motif was mutated, the activation of Sult1e1 was suppressed significantly. This chapter also describes the use of a phospho-peptide antibody (αP-S216) in the chromatin immunoprecipitation (ChIP) assay, and the co-immunoprecipitation (Co-IP) assay visualized by Western blot analysis.

Regulation of TET2 gene expression and 5mC oxidation in breast cancer cells by estrogen signaling

Estrogen signaling plays important roles in diverse physiological and pathophysiological processes. However, the relationship between estrogen signaling and epigenetic regulation is not fully understood. Here, we explored the effect of estrogen signaling on the expression of Ten-Eleven Translocation (TET) family genes and DNA hydroxylmethylation in estrogen receptor alpha positive (ERα+) breast cancer cells. By analyzing the RNA-seq data, we identified TET2 as an estradiol (E2)-responsive gene in ERα+ MCF7 cells. RT-qPCR and Western blot analyses confirmed that both the mRNA and protein levels of TET2 gene were upregulated in MCF7 cells by E2 treatment. ChIP-seq and qPCR analyses showed that the enrichment of ERα and H3K27ac on the upstream regulatory regions of TET2 gene was increased in MCF7 cells upon E2 treatment. Moreover, E2 treatment also led to a significant increase in the global 5-hydroxymethylcytosine (5hmC) level, while knockout of TET2 abolished such E2-induced 5hmC increase. Conversely, treatment with ICI 182780, a potent and selective estrogen receptor degrader (SERD), inhibited TET2 gene expression and down-regulated the 5hmC level in MCF7 cells. Taken together, our study identified an ERα/TET2/5hmC epigenetic pathway, which may participate in the estrogen-associated physiological and pathophysiological processes.

p21 activated kinase-1 and tamoxifen - A deadly nexus impacting breast cancer outcomes

Tamoxifen is a commonly used drug in the treatment of ER + ve breast cancers since 1970. However, development of resistance towards tamoxifen limits its remarkable clinical success. In this review, we have attempted to provide a brief overview of multiple mechanism that may lead to tamoxifen resistance, with a special emphasis on the roles played by the oncogenic kinase- PAK1. Analysing the genomic data sets available in the cBioPortal, we found that PAK1 gene amplification significantly affects the Relapse Free Survival of the ER + ve breast cancer patients. While PAK1 is known to promote tamoxifen resistance by phosphorylating ERα at Ser305, existing literature suggests that PAK1 can fuel up tamoxifen resistance obliquely by phosphorylating other substrates. We have summarised some of the approaches in the mass spectrometry based proteomics, which would enable us to study the tamoxifen resistance specific phosphoproteomic landscape of PAK1. We also propose that elucidating the multiple mechanisms by which PAK1 promotes tamoxifen resistance might help us discover druggable targets and biomarkers.

FLTX2: A Novel Tamoxifen Derivative Endowed with Antiestrogenic, Fluorescent, and Photosensitizer Properties

Tamoxifen is the most widely used selective modulator of estrogen receptors (SERM) and the first strategy as coadjuvant therapy for the treatment of estrogen-receptor (ER) positive breast cancer worldwide. In spite of such success, tamoxifen is not devoid of undesirable effects, the most life-threatening reported so far affecting uterine tissues. Indeed, tamoxifen treatment is discouraged in women under risk of uterine cancers. Recent molecular design efforts have endeavoured the development of tamoxifen derivatives with antiestrogen properties but lacking agonistic uterine tropism. One of this is FLTX2, formed by the covalent binding of tamoxifen as ER binding core, 7-nitrobenzofurazan (NBD) as the florescent dye, and Rose Bengal (RB) as source for reactive oxygen species. Our analyses demonstrate (1) FLTX2 is endowed with similar antiestrogen potency as tamoxifen and its predecessor FLTX1, (2) shows a strong absorption in the blue spectral range, associated to the NBD moiety, which efficiently transfers the excitation energy to RB through intramolecular FRET mechanism, (3) generates superoxide anions in a concentration- and irradiation time-dependent process, and (4) Induces concentration- and time-dependent MCF7 apoptotic cell death. These properties make FLTX2 a very promising candidate to lead a novel generation of SERMs with the endogenous capacity to promote breast tumour cell death in situ by photosensitization.

Coexpression of Smac/DIABLO and Estrogen Receptor in breast cancer

BACKGROUND

Smac/DIABLO is a proapoptotic protein deregulated in breast cancer, with a controversial role as a tumor marker, possibly due to a lack of correlative mRNA and protein analyses.

OBJECTIVE

To investigate the association of Smac/DIABLO gene and protein levels with clinical variables in breast cancer patients.

METHODS

Smac/DIABLO mRNA expression was analyzed by qPCR in 57 frozen tissues, whereas protein levels were assessed by immunohistochemistry in 82 paraffin-embedded tissues. Survivin mRNA levels were also measured. In vitro assays were performed to investigate possible regulators of Smac/DIABLO.

RESULTS

Higher levels of Smac/DIABLO mRNA and protein were found in estrogen receptor (ER)-positive samples (p= 0.0054 and p= 0.0043, respectively) in comparison to ER-negative tumors. A negligible positive association was found between Smac/DIABLO and survivin expression. In vitro assays showed that Smac/DIABLO is not regulated by ER and, conversely, it does not participate in ER expression modulation.

CONCLUSIONS

mRNA and protein levels of Smac/DIABLO were increased in ER-positive breast tumors in comparison with ER-negative samples, although the mechanism of this regulation is still unknown. Public databases showed a possible clinical relevance for this association.

Cyclin-dependent kinase inhibitors (CDKIs) and the DNA damage response: The link between signaling pathways and cancer

At the cellular level, DNA repair mechanisms are crucial in maintaining both genomic integrity and stability. DNA damage appears to be a central culprit in tumor onset and progression. Cyclin-dependent kinases (CDKs) and their regulatory partners coordinate the cell cycle progression. Aberrant CDK activity has been linked to a variety of cancers through deregulation of cell-cycle control. Besides DNA damaging agents and chromosome instability (CIN), disruptions in the levels of cell cycle regulators including cyclin-dependent kinase inhibitors (CDKIs) would result in unscheduled proliferation and cell division. The INK4 and Cip/Kip (CDK interacting protein/kinase inhibitor protein) family of CDKI proteins are involved in cell cycle regulation, transcription regulation, apoptosis, and cell migration. A thorough understanding of how these CDKIs regulate the DNA damage response through multiple signaling pathways may provide an opportunity to design efficient treatment strategies to inhibit carcinogenesis.

Generating a Precision Endoxifen Prediction Algorithm to Advance Personalized Tamoxifen Treatment in Patients with Breast Cancer

Tamoxifen is an endocrine treatment for hormone receptor positive breast cancer. The effectiveness of tamoxifen may be compromised in patients with metabolic resistance, who have insufficient metabolic generation of the active metabolites endoxifen and 4-hydroxy-tamoxifen. This has been challenging to validate due to the lack of measured metabolite concentrations in tamoxifen clinical trials. CYP2D6 activity is the primary determinant of endoxifen concentration. Inconclusive results from studies investigating whether CYP2D6 genotype is associated with tamoxifen efficacy may be due to the imprecision in using CYP2D6 genotype as a surrogate of endoxifen concentration without incorporating the influence of other genetic and clinical variables. This review summarizes the evidence that active metabolite concentrations determine tamoxifen efficacy. We then introduce a novel approach to validate this relationship by generating a precision endoxifen prediction algorithm and comprehensively review the factors that must be incorporated into the algorithm, including genetics of CYP2D6 and other pharmacogenes. A precision endoxifen algorithm could be used to validate metabolic resistance in existing tamoxifen clinical trial cohorts and could then be used to select personalized tamoxifen doses to ensure all patients achieve adequate endoxifen concentrations and maximum benefit from tamoxifen treatment.

The Breast Cancer Stem Cells Traits and Drug Resistance

Drug resistance is a major challenge in breast cancer (BC) treatment at present. Accumulating studies indicate that breast cancer stem cells (BCSCs) are responsible for the BC drugs resistance, causing relapse and metastasis in BC patients. Thus, BCSCs elimination could reverse drug resistance and improve drug efficacy to benefit BC patients. Consequently, mastering the knowledge on the proliferation, resistance mechanisms, and separation of BCSCs in BC therapy is extremely helpful for BCSCs-targeted therapeutic strategies. Herein, we summarize the principal BCSCs surface markers and signaling pathways, and list the BCSCs-related drug resistance mechanisms in chemotherapy (CT), endocrine therapy (ET), and targeted therapy (TT), and display therapeutic strategies for targeting BCSCs to reverse drug resistance in BC. Even more importantly, more attention should be paid to studies on BCSC-targeted strategies to overcome the drug resistant dilemma of clinical therapies in the future.

A Closer Look at Estrogen Receptor Mutations in Breast Cancer and Their Implications for Estrogen and Antiestrogen Responses

Breast cancer (BC) is the most common cancer among women worldwide. More than 70% of BC cases express estrogen receptor alpha (ERα), a central transcription factor that stimulates the proliferation of breast cancer cells, usually in the presence of estrogen. While most cases of ER-positive BC initially respond to antiestrogen therapies, a high percentage of cases develop resistance to treatment over time. The recent discovery of mutated forms of ERα that result in constitutively active forms of the receptor in the metastatic-resistance stage of BC has provided a strong rationale for the development of new antiestrogens. These molecules targeting clinically relevant ERα mutants and a combination with other pharmacological inhibitors of specific pathways may constitute alternative treatments to improve clinical practice in the fight against metastatic-resistant ER-positive BC. In this review, we summarize the latest advances regarding the particular involvement of point mutations of ERα in endocrine resistance. We also discuss the involvement of synonymous ERα mutations with respect to co-translational folding of the receptor and ribosome biogenesis in breast carcinogenesis.

CNA2Subpathway: identification of dysregulated subpathway driven by copy number alterations in cancer

Biological pathways reflect the key cellular mechanisms that dictate disease states, drug response and altered cellular function. The local areas of pathways are defined as subpathways (SPs), whose dysfunction has been reported to be associated with the occurrence and development of cancer. With the development of high-throughput sequencing technology, identifying dysfunctional SPs by using multi-omics data has become possible. Moreover, the SPs are not isolated in the biological system but interact with each other. Here, we propose a network-based calculated method, CNA2Subpathway, to identify dysfunctional SPs is driven by somatic copy number alterations (CNAs) in cancer through integrating pathway topology information, multi-omics data and SP crosstalk. This provides a novel way of SP analysis by using the SP interactions in the system biological level. Using data sets from breast cancer and head and neck cancer, we validate the effectiveness of CNA2Subpathway in identifying cancer-relevant SPs driven by the somatic CNAs, which are also shown to be associated with cancer immune and prognosis of patients. We further compare our results with five pathway or SP analysis methods based on CNA and gene expression data without considering SP crosstalk. With these analyses, we show that CNA2Subpathway could help to uncover dysfunctional SPs underlying cancer via the use of SP crosstalk. CNA2Subpathway is developed as an R-based tool, which is freely available on GitHub (https://github.com/hanjunwei-lab/CNA2Subpathway).

Digital Image Analysis of Ki-67 Stained Tissue Microarrays and Recurrence in Tamoxifen-Treated Breast Cancer Patients

Purpose

The proliferation marker Ki-67 has been used as a prognostic marker to separate low- and high-risk breast cancer subtypes and guide treatment decisions for adjuvant chemotherapy. The association of Ki-67 with response to tamoxifen therapy is unclear. High-throughput automated scoring of Ki-67 might enable standardization of quantification and definition of clinical cut-off values. We hypothesized that digital image analysis (DIA) of Ki-67 can be used to evaluate proliferation in breast cancer tumors, and that Ki-67 may be associated with tamoxifen resistance in early-stage breast cancer.

Patients and Methods

Here, we apply DIA technology from Visiopharm using a custom designed algorithm for quantifying the expression of Ki-67, in a case–control study nested in the Danish Breast Cancer Group clinical database, consisting of stages I, II, or III breast cancer patients of 35–69 years of age, diagnosed during 1985–2001, in the Jutland peninsula, Denmark. We assessed DIA-Ki-67 score on tissue microarrays (TMAs) from breast cancer patients in a case–control study including 541 ER-positive and 300 ER-negative recurrent cases and their non-recurrent controls, matched on ER-status, cancer stage, menopausal status, year of diagnosis, and county of residence. We used logistic regression to estimate odds ratios and associated 95% confidence intervals to determine the association of Ki-67 expression with recurrence risk, adjusting for matching factors, chemotherapy, type of surgery, receipt of radiation therapy, age category, and comorbidity.

Results

Ki-67 was not associated with increased risk of recurrence in tamoxifen-treated patients (ORadj =0.72, 95% CI 0.54, 0.96) or ER-negative patients (ORadj =0.85, 95% CI 0.54, 1.34).

Conclusion

Our findings suggest that Ki-67 digital image analysis in TMAs is not associated with increased risk of recurrence among tamoxifen-treated ER-positive breast cancer or ER-negative breast cancer patients. Overall, our findings do not support an increased risk of recurrence associated with Ki-67 expression.

A novel tumor suppressor ZBTB1 regulates tamoxifen resistance and aerobic glycolysis through suppressing HER2 expression in breast cancer

Transcriptional repressor zinc finger and BTB domain containing 1 (ZBTB1) is required for DNA repair. Because DNA repair defects often underlie genome instability and tumorigenesis, we determined to study the role of ZBTB1 in cancer. In this study, we found that ZBTB1 is down-regulated in breast cancer and this down-regulation is associated with poor outcome of breast cancer patients. ZBTB1 suppresses breast cancer cell proliferation and tumor growth. The majority of breast cancers are estrogen receptor (ER) positive and selective estrogen receptor modulators such as tamoxifen have been widely used in the treatment of these patients. Unfortunately, many patients develop resistance to endocrine therapy. Tamoxifen-resistant cancer cells often exhibit higher HER2 expression and an increase of glycolysis. Our data revealed that ZBTB1 plays a critical role in tamoxifen resistance in vitro and in vivo To see if ZBTB1 regulates HER2 expression, we tested the recruitments of ZBTB1 on HER2 regulatory sequences. We observed that over-expressed ZBTB1 occupies the estrogen receptor α (ERα)-binding site of the HER2 intron in tamoxifen-resistant cells, suppressing tamoxifen-induced transcription. In an effort to identify potential microRNAs (miRNAs) regulating ZBTB1, we found that miR-23b-3p directly targets ZBTB1. MiR-23b-3p regulates HER2 expression and tamoxifen resistance via targeting ZBTB1. Finally, we found that miR-23b-3p/ZBTB1 regulates aerobic glycolysis in tamoxifen-resistant cells. Together, our data demonstrate that ZBTB1 is a tumor suppressor in breast cancer cells and that targeting the miR-23b-3p/ZBTB1 may serve as a potential therapeutic approach for the treatment of tamoxifen resistant breast cancer.

USP22 positively modulates ERα action via its deubiquitinase activity in breast cancer

Estrogen receptor α (ERα) is the crucial factor in ERα-positive breast cancer progression. Endocrine therapies targeting ERα signaling is one of the widely used therapeutic strategies for breast cancer. However, a large number of the patients become refractory to therapy. Abnormal expression of ERα co-regulator facilitates breast cancer development and tendency of endocrine resistance. Thus, it is necessary to discover the novel co-regulators modulating ERα action. Here, we demonstrate that histone deubiquitinase USP22 is highly expressed in breast cancer samples compared with that in the benign tissue, and high expression of USP22 was significantly associated with poorer overall survival in BCa samples. Moreover, USP22 associates with ERα to be involved in maintenance of ERα stability. USP22 enhances ERα-induced transactivation. We further provide the evidence that USP22 is recruited together with ERα to cis-regulatory elements of ERα target gene. USP22 promotes cell growth even under hypoxia condition and with the treatment of ERα antagonist in breast cancer cells. Importantly, the deubiquitination activity of USP22 is required for its functions on maintenance of ERα stability, thereby enhancing ERα action and conferring endocrine resistance in breast cancer.

HDAC3-ERα Selectively Regulates TNF-α-Induced Apoptotic Cell Death in MCF-7 Human Breast Cancer Cells via the p53 Signaling Pathway

Tumor necrosis factor-α (TNF-α) plays a significant role in inflammation and cancer-related apoptosis. We identified a TNF-α-mediated epigenetic mechanism of apoptotic cell death regulation in estrogen receptor-α (ERα)-positive human breast cancer cells. To assess the apoptotic effect of TNF-α, annexin V/ propidium iodide (PI) double staining, cell viability assays, and Western blotting were performed. To elucidate this mechanism, histone deacetylase (HDAC) activity assay and immunoprecipitation (IP) were conducted; the mechanism was subsequently confirmed through chromatin IP (ChIP) assays. Finally, we assessed HDAC3-ERα-mediated apoptotic cell death after TNF-α treatment in ERα-positive human breast cancer (MCF-7) cells via the transcriptional activation of p53 target genes using luciferase assay and quantitative reverse transcription PCR. The TNF-α-induced selective apoptosis in MCF-7 cells was negatively regulated by the HDAC3-ERα complex in a caspase-7-dependent manner. HDAC3 possessed a p53-binding element, thus suppressing the transcriptional activity of its target genes. In contrast, MCF-7 cell treatment with TNF-α led to dissociation of the HDAC3-ERα complex and substitution of the occupancy on the promoter by the p53-p300 complex, thus accelerating p53 target gene expression. In this process, p53 stabilization was accompanied by its acetylation. This study showed that p53-mediated apoptosis in ERα-positive human breast cancer cells was negatively regulated by HDAC3-ERα in a caspase-7-dependent manner. Therefore, these proteins have potential application in therapeutic strategies.

Antitumor activity of Z-endoxifen in aromatase inhibitor-sensitive and aromatase inhibitor-resistant estrogen receptor-positive breast cancer

BACKGROUND

The tamoxifen metabolite, Z-endoxifen, demonstrated promising antitumor activity in endocrine-resistant estrogen receptor-positive (ER+) breast cancer. We compared the antitumor activity of Z-endoxifen with tamoxifen and letrozole in the letrozole-sensitive MCF7 aromatase expressing model (MCF7AC1), as well as with tamoxifen, fulvestrant, exemestane, and exemestane plus everolimus in a letrozole-resistant MCF7 model (MCF7LR).

METHODS

MCF7AC1 tumor-bearing mice were randomized to control (no drug), letrozole (10 μg/day), tamoxifen (500 μg/day), or Z-endoxifen (25 and 75 mg/kg). Treatment in the letrozole arm was continued until resistance developed. MCF7LR tumor-bearing mice were then randomized to Z-endoxifen (50 mg/kg) or tamoxifen for 4 weeks and tumors harvested for microarray and immunohistochemistry analysis. The antitumor activity of Z-endoxifen in the MCF7LR tumors was further compared in a second in vivo study with exemestane, exemestane plus everolimus, and fulvestrant.

RESULTS

In the MCF7AC1 tumors, both Z-endoxifen doses were significantly superior to control and tamoxifen in reducing tumor volumes at 4 weeks. Additionally, the 75 mg/kg Z-endoxifen dose was additionally superior to letrozole. Prolonged letrozole exposure resulted in resistance at 25 weeks. In MCF7LR tumor-bearing mice, Z-endoxifen significantly reduced tumor volumes compared to tamoxifen, letrozole, and exemestane, with no significant differences compared to exemestane plus everolimus and fulvestrant. Additionally, compared to tamoxifen, Z-endoxifen markedly inhibited ERα target genes, Ki67 and Akt expression in vivo.

CONCLUSION

In endocrine-sensitive and letrozole-resistant breast tumors, Z-endoxifen results in robust antitumor and antiestrogenic activity compared to tamoxifen and aromatase inhibitor monotherapy. These data support the ongoing development of Z-endoxifen.

Distinct Roles of mTOR Targets S6K1 and S6K2 in Breast Cancer

The mechanistic target of rapamycin (mTOR) is a master regulator of protein translation, metabolism, cell growth and proliferation. It forms two complexes, mTOR complex 1 (mTORC1) and 2 (mTORC2). mTORC1 is frequently deregulated in many cancers, including breast cancer, and is an important target for cancer therapy. The immunosuppressant drug rapamycin and its analogs that inhibit mTOR are currently being evaluated for their potential as anti-cancer agents, albeit with limited efficacy. mTORC1 mediates its function via its downstream targets 40S ribosomal S6 kinases (S6K) and eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1). There are two homologs of S6K: S6K1 and S6K2. Most of the earlier studies focused on S6K1 rather than S6K2. Because of their high degree of structural homology, it was generally believed that they behave similarly. Recent studies suggest that while they may share some functions, they may also exhibit distinct or even opposite functions. Both homologs have been implicated in breast cancer, although how they contribute to breast cancer may differ. The purpose of this review article is to compare and contrast the expression, structure, regulation and function of these two S6K homologs in breast cancer.

Estrogen Induces Mammary Ductal Dysplasia via the Upregulation of Myc Expression in a DNA-Repair-Deficient Condition

Mammary ductal dysplasia is a phenotype observed in precancerous lesions and early-stage breast cancer. However, the mechanism of dysplasia formation remains elusive. Here we show, by establishing a novel dysplasia model system, that estrogen, a female hormone, has the potential to cause mammary ductal dysplasia. We injected estradiol (E2), the most active form of estrogen, daily into scid mice with a defect in non-homologous end joining repair and observed dysplasia formation with cell proliferation at day 30. The protooncogene Myc is a downstream target of estrogen signaling, and we found that its expression is augmented in mammary epithelial cells in this dysplasia model. Treatment with a Myc inhibitor reduced E2-induced dysplasia formation. Moreover, we found that isoflavones inhibited E2-induced dysplasia formation. Our dysplasia model system provides insights into the mechanistic understanding of breast tumorigenesis and the development of breast cancer prevention.

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Excess amount of estrogen administration in scid mice induces mammary ductal dysplasia

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E2-induced Myc expression is one of the causes of dysplasia formation

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Progesterone and isoflavones have a potential to prevent E2-induced dysplasia

TOX3 Promotes Ovarian Estrogen Synthesis: An RNA-Sequencing and Network Study

BACKGROUND

Women who undergo chronic exposure to excessive estrogen are at a high risk of developing breast cancer. TOX3 has been reported to be highly expressed in breast tumors and is closely related to estrogen receptors. However, the effect of TOX3 on estrogen synthesis remains poorly understood.

METHODS

Using lentiviruses as a vector, we stably overexpressed TOX3 in the ovarian granulosa cell line KGN, the cells where estradiol is primarily produced, to investigate its role in estrogen production as well as cell viability and apoptosis. RNA-Sequencing was applied to uncover the global gene expression upon TOX3 overexpression.

RESULTS

We observed an increased level of cell viability and a reduced cell apoptosis rate after TOX3 overexpression, and the level of estradiol in the cell culture supernatant also increased significantly. Gene set enrichment analysis of the transcriptome showed that the ovarian steroidogenesis pathway was significantly enriched. Similarly, pathway mapping using the Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analyses also showed that TOX3 overexpression affects the ovarian steroidogenesis pathway. Further experiments showed that upregulated FSHR, CYP19A1, and BMP6 accounted for the enhanced estrogen synthesis.

CONCLUSION

Our study demonstrated that TOX3 quantitatively and qualitatively stimulates estrogen synthesis by enhancing estrogen signaling pathway-related gene expression in ovarian granulosa cells. These findings suggest that TOX3 may play a vital role in the pathogenesis of breast cancer.

Obesity as potential breast cancer risk factor for postmenopausal women

Breast cancer is the second highest prevalent cancer globally after lung cancer with 2.09 million cases during 2018. Adults about 1.9 billion were overweight and over 650 million out of these were obese during 2016. There is a significant relationship between breast cancer risk and obesity. Premature menopause and premenopausal obesity diminish the risk whereas postmenopausal obesity amplifies the risk, because adipose tissue acts as the major reservoir for estrogen biosynthesis after menopause. Lofty estrogen levels in serum along with enhanced peripheral site production of estrogen have been viewed as major reasons of developing breast cancer in overweight postmenopausal women. This review explains body fat as a peripheral site for estrogen biosynthesis, estrogen exposure affecting body fat distribution, and the mechanism of estrogen production from body fats.

Abrupt involution induces inflammation, estrogenic signaling, and hyperplasia linking lack of breastfeeding with increased risk of breast cancer

Background

A large collaborative analysis of data from 47 epidemiological studies concluded that longer duration of breastfeeding reduces the risk of developing breast cancer. Despite the strong epidemiological evidence, the molecular mechanisms linking prolonged breastfeeding to decreased risk of breast cancer remain poorly understood.

Methods

We modeled two types of breastfeeding behaviors in wild type FVB/N mice: (1) normal or gradual involution of breast tissue following prolonged breastfeeding and (2) forced or abrupt involution following short-term breastfeeding. To accomplish this, pups were gradually weaned between 28 and 31 days (gradual involution) or abruptly at 7 days postpartum (abrupt involution). Mammary glands were examined for histological changes, proliferation, and inflammatory markers by immunohistochemistry. Fluorescence-activated cell sorting was used to quantify mammary epithelial subpopulations. Gene set enrichment analysis was used to analyze gene expression data from mouse mammary luminal progenitor cells. Similar analysis was done using gene expression data generated from human breast samples obtained from parous women enrolled on a tissue collection study, OSU-2011C0094, and were undergoing reduction mammoplasty without history of breast cancer.

Results

Mammary glands from mice that underwent abrupt involution exhibited denser stroma, altered collagen composition, higher inflammation and proliferation, increased estrogen receptor α and progesterone receptor expression compared to those that underwent gradual involution. Importantly, when aged to 4 months postpartum, mice that were in the abrupt involution cohort developed ductal hyperplasia and squamous metaplasia. Abrupt involution also resulted in a significant expansion of the luminal progenitor cell compartment associated with enrichment of Notch and estrogen signaling pathway genes. Breast tissues obtained from healthy women who breastfed for < 6 months vs ≥ 6 months showed significant enrichment of Notch signaling pathway genes, along with a trend for enrichment for luminal progenitor gene signature similar to what is observed in BRCA1 mutation carriers and basal-like breast tumors.

Conclusions

We report here for the first time that forced or abrupt involution of the mammary glands following pregnancy and lack of breastfeeding results in expansion of luminal progenitor cells, higher inflammation, proliferation, and ductal hyperplasia, a known risk factor for developing breast cancer.

Electronic supplementary material

The online version of this article (10.1186/s13058-019-1163-7) contains supplementary material, which is available to authorized users.

Identification of 10-dehydrooxyglycyuralin E as a selective human estrogen receptor alpha partial agonist

Selective estrogen receptor modulators (SERMs) act as either agonist or antagonist of estrogen receptor (ER) in a tissue selective manner and have been used in several diseases such as breast cancer, postmenopausal syndrome, osteoporosis, and cardiovascular diseases. However, current SERMs may also increase the risk of serious side effects and trigger drug resistance. Herein, a screening program, that was designed to search for novel SERMs, resulted in the identification of a series of 2-arylbenzofuran-containing compounds that are ligands for ERα, when applying the Gaussia-luciferase reporter assay. One of these compounds, 10-dehydrooxyglycyuralin E (T9) was chemically synthesized. T9 showed anti-estrogenic/proliferative activity in ERα-positive breast cancer cells. Pretreatment of T9 prevented the mRNA expression of GREB1, which is an estrogen response gene. Furthermore, by an in silico docking simulation study we demonstrated that T9 showed interactions directly to ERα. Taken together, these results demonstrated that T9 is a candidate of SERMs and a useful seed compound for the foundation of the selective activity of SERMs.

Grainyhead-like Protein 2: The Emerging Role in Hormone-Dependent Cancers and Epigenetics

In mammals, the grainyhead-like transcription factor (GRHL) family is composed of three nuclear proteins that are responsible for driving epithelial cell fate: GRHL1, GRHL2, and GRHL3. GRHL2 is important in maintaining proper tubulogenesis during development and in suppressing the epithelial-to-mesenchymal transition. Within the last decade, evidence indicates both tumor-suppressive and oncogenic roles for GRHL2 in various types of cancers. Recent studies suggest that GRHL2 may be especially important in hormone-dependent cancers, as correlative relationships exist between GRHL2 and various steroid receptors, such as the androgen and estrogen receptors. Acting as a pioneer factor and coactivator, GRHL2 may directly affect steroid receptor transcriptional activity. This review will highlight recent discoveries of GRHL2 activity in cancer and in maintaining the epithelial state, while also exploring recent literature on the role of GRHL2 in hormone-dependent cancers and epigenetics.

The Functions of DNA Damage Factor RNF8 in the Pathogenesis and Progression of Cancer

The really interesting new gene (RING) finger protein 8 (RNF8) is a central factor in DNA double strand break (DSB) signal transduction. DSB damage is the most toxic type of DNA damage to cells and is related to genomic instability. Multiple roles for RNF8 have been identified in DNA damage response as well as in other functions, such as telomere protection, cell cycle control and transcriptional regulation. These functions are closely correlated to tumorigenesis and cancer progression. Indeed, deficiency of RNF8 caused spontaneous tumorigenesis in a mouse model. Deciphering these mechanisms of RNF8 may shed light on strategies for cancer treatment. In this review, we summarize the current understanding of both classical and nonclassical functions of RNF8, and discuss its roles in the pathogenesis and progression of tumor.

Flightless-I mediates the repression of estrogen receptor α target gene expression by the glucocorticoid receptor in MCF-7 cells

The human homologue of flightless-I (FLII) belong to the gelsolin protein family and contain a gelsolin-like domain at the C-terminus and a leucine-rich repeat (LRR) domain at the N-terminus. FLII regulates estrogen receptor alpha (ERα) and glucocorticoid receptor (GR)-mediated transcription by direct interaction through different domains, suggestive of its potential role in the crosstalk between the ERα and GR signaling pathway. Here, we demonstrate that FLII plays a critical role in GR-mediated repression of ERα target gene expression. In FLII-depleted cells, the reduction in 17-β-estradiol (E2)-induced ERα occupancy following treatment with dexamethasone (Dex) at the estrogen responsive element (ERE) site of the ERα target gene was significantly inhibited. The ERE binding of GR by the cotreatment with E2 and Dex was significantly inhibited by FLII depletion, indicating that FLII is required for the recruitment of GR at the ERE sites of ERα target genes. In addition, the recruitment of ERα-induced FLII to ERE sites was significantly reduced by Dex treatment. In protein binding assays, GR inhibited the E2-induced interaction between ERα and FLII, suggesting that GR interferes with the binding of ERα and FLII at the ERα target genes, resulting in the release of ERα and FLII from EREs. Taken together, our data reveal an unknown mechanism by which the transcription coactivator FLII regulates the GR-mediated repression of ERα target gene expression in MCF-7 cells.

Prognostic relevance of RIP140 and ERβ expression in unifocal versus multifocal breast cancers: a preliminary report

The aim of this study was to investigate the expression of two nuclear receptor transcriptional coregulators, namely RIP140 (receptor-interacting protein of 140 kDa) and LCoR (ligand-dependent corepressor) in unifocal versus multifocal breast cancers. The expression of these two proteins was analyzed by immunohistochemistry in a matched-pair cohort of 21 unifocal and 21 multifocal breast tumors. The expression of the two estrogen receptors (ERα and ERβ) was studied in parallel. RIP140 and LCoR levels appeared lower in unifocal tumors compared to multifocal samples (decreased of immune-reactive scores and reduced number of high expressing cells). In both tumor types, RIP140 and LCoR expression was correlated with each other and with expression of ERβ. Very interestingly, the expression of RIP140, LCoR, and ERβ was inversely correlated with overall survival only for the unifocal group. The negative correlation with overall and recurrence free survival was more pronounced in patients whose unifocal tumors expressed high levels of both RIP140 and ERβ. Altogether, this preliminary report indicates that the ERβ/RIP140 signaling is altered in unifocal breast cancers and correlated with patient outcome. Further investigation is needed to decipher the molecular mechanisms and the biological relevance of this deregulation.

The Emerging Roles of Steroid Hormone Receptors in Ductal Carcinoma in Situ (DCIS) of the Breast

Ductal carcinoma in situ (DCIS) is a non-obligate precursor to most types of invasive breast cancer (IBC). Although it is estimated only one third of untreated patients with DCIS will progress to IBC, standard of care for treatment is surgery and radiation. This therapeutic approach combined with a lack of reliable biomarker panels to predict DCIS progression is a major clinical problem. DCIS shares the same molecular subtypes as IBC including estrogen receptor (ER) and progesterone receptor (PR) positive luminal subtypes, which encompass the majority (60-70%) of DCIS. Compared to the established roles of ER and PR in luminal IBC, much less is known about the roles and mechanism of action of estrogen (E2) and progesterone (P4) and their cognate receptors in the development and progression of DCIS. This is an underexplored area of research due in part to a paucity of suitable experimental models of ER+/PR + DCIS. This review summarizes information from clinical and observational studies on steroid hormones as breast cancer risk factors and ER and PR as biomarkers in DCIS. Lastly, we discuss emerging experimental models of ER+/PR+ DCIS.

Expression of calcium pumps is differentially regulated by histone deacetylase inhibitors and estrogen receptor alpha in breast cancer cells

Background

Remodeling of Ca²⁺ signaling is an important step in cancer progression, and altered expression of members of the Ca²⁺ signaling toolkit including the plasma membrane Ca²⁺ ATPases (PMCA proteins encoded by ATP2B genes) is common in tumors.

Methods

In this study PMCAs were examined in breast cancer datasets and in a variety of breast cancer cell lines representing different subtypes. We investigated how estrogen receptor alpha (ER-α) and histone deacetylase (HDAC) inhibitors regulate the expression of these pumps.

Results

Three distinct datasets displayed significantly lower ATP2B4 mRNA expression in invasive breast cancer tissue samples compared to normal breast tissue, whereas the expression of ATP2B1 and ATP2B2 was not altered. Studying the protein expression profiles of Ca²⁺ pumps in a variety of breast cancer cell lines revealed low PMCA4b expression in the ER-α positive cells, and its marked upregulation upon HDAC inhibitor treatments. PMCA4b expression was also positively regulated by the ER-α pathway in MCF-7 cells that led to enhanced Ca²⁺ extrusion capacity in response to 17β-estradiol (E2) treatment. E2-induced PMCA4b expression was further augmented by HDAC inhibitors. Surprisingly, E2 did not affect the expression of PMCA4b in other ER-α positive cells ZR-75-1, T-47D and BT-474. These findings were in good accordance with ChIP-seq data analysis that revealed an ER-α binding site in the ATP2B4 gene in MCF-7 cells but not in other ER-α positive tumor cells. In the triple negative cells PMCA4b expression was relatively high, and the effect of HDAC inhibitor treatment was less pronounced as compared to that of the ER-α positive cells. Although, the expression of PMCA4b was relatively high in the triple negative cells, a fraction of the protein was found in intracellular compartments that could interfere with the cellular function of the protein.

Conclusions

Our results suggest that the expression of Ca²⁺ pumps is highly regulated in breast cancer cells in a subtype specific manner. Our results suggest that hormonal imbalances, epigenetic modifications and impaired protein trafficking could interfere with the expression and cellular function of PMCA4b in the course of breast cancer progression.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4945-x) contains supplementary material, which is available to authorized users.

The impact of transcription on metabolism in prostate and breast cancers

Metabolic dysregulation is regarded as an important driver in cancer development and progression. The impact of transcriptional changes on metabolism has been intensively studied in hormone-dependent cancers, and in particular, in prostate and breast cancer. These cancers have strong similarities in the function of important transcriptional drivers, such as the oestrogen and androgen receptors, at the level of dietary risk and epidemiology, genetics and therapeutically. In this review, we will focus on the function of these nuclear hormone receptors and their downstream impact on metabolism, with a particular focus on lipid metabolism. We go on to discuss how lipid metabolism remains dysregulated as the cancers progress. We conclude by discussing the opportunities that this presents for drug repurposing, imaging and the development and testing of new therapeutics and treatment combinations.

Polyubiquitination inhibition of estrogen receptor alpha and its implications in breast cancer

Estrogen receptor alpha (ERα) is detected in more than 70% of the cases of breast cancer. Nuclear activity of ERα, a transcriptional regulator, is linked to the development of mammary tumors, whereas the extranuclear activity of ERα is related to endocrine therapy resistance. ERα polyubiquitination is induced by the estradiol hormone, and also by selective estrogen receptor degraders, resulting in ERα degradation via the ubiquitin proteasome system. Moreover, polyubiquitination is related to the ERα transcription cycle, and some E3-ubiquitin ligases also function as coactivators for ERα. Several studies have demonstrated that ERα polyubiquitination is inhibited by multiple mechanisms that include posttranslational modifications, interactions with coregulators, and formation of specific protein complexes with ERα. These events are responsible for an increase in ERα protein levels and deregulation of its signaling in breast cancers. Thus, ERα polyubiquitination inhibition may be a key factor in the progression of breast cancer and resistance to endocrine therapy.

Breast cancer amelioration by Butea monosperma in-vitro and in-vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Butea monosperma belonging to family Fabaceae is used in the Indian traditional medicine (Ayurveda) for various ailments including abdominal tumors and possess anti-estrogenic activity.

AIM OF THE STUDY

The present study is aimed at investigating the chemo-preventive potential of Butea monosperma in breast cancer and elucidating it's mechanism of action by assessing its effect on key processes like apoptosis, angiogenesis and metastasis.

METHODS

Cytotoxic potential of methanol extract of Butea monosperma flower (MEBM) was tested in MCF-7 (estrogen receptor positive), MDA-MB-231 (triple negative) and MDA-MB-453 (HER2 positive) human breast cancer cells by MTT assay. Chemo-preventive potential was evaluated in-vivo in Methylnitrosourea (MNU) induced mammary cancer in nulliparous Sprague-Dawley rats. The mechanism for anticancer potential was screened by in-vitro studies involving Annexin V- FITC assay (apoptosis), Chick Chorioallantoic Membrane assay (angiogenesis) and Migration assay (metastasis). Statistical analysis was done by one way and two way ANOVA (for Growth Rate and feed consumption efficiency) followed by post hoc Bonferroni's test with P value < 0.05.

RESULTS

It is observed that the exposure of MEBM, at various concentrations and time intervals to different cell lines, resulted in decreased cell proliferation. The IC₅₀ value of MCF-7 cells was found significantly less than that of MDA-MB-231 and MDA-MB-453 cells, which indicated that the extract of said medicinal plant were more potent inhibitors of estrogen positive breast cancer cells than other types of breast cancer cells in vitro. Corroborative evidences were acquired in MNU actuated mammary carcinogenesis where MEBM constricted tumor parameters, decreased expression of estrogen and progesterone, nucleic acid content and increased latency period. MEBM also induced apoptosis, inhibited angiogenesis and metastasis in-vitro.

CONCLUSION

Selective cytotoxic activity in MCF-7 estrogen positive breast cancer cells and inhibition of growth of mammary carcinoma in-vivo by methanol extract of Butea monosperma flowers (MEBM) suggests chemo-prevention through modulation of estrogen and progesterone receptor, apoptotic, anti-angiogenesis and anti-metastatic activity.

Obesity and breast cancer - Role of estrogens and the molecular underpinnings of aromatase regulation in breast adipose tissue

One in eight women will develop breast cancer over their lifetime making it the most common female cancer. The cause of breast cancer is multifactorial and includes hormonal, genetic and environmental cues. Obesity is now an accepted risk factor for breast cancer in postmenopausal women, particularly for the hormone-dependent subtype of breast cancer. Obesity, which is characterized by an excess accumulation of body fat, is at the origin of chronic inflammation of white adipose tissue and is associated with dramatic changes in the biology of adipocytes leading to their dysfunction. Inflammatory factors found in the breast of obese women considerably impact estrogen signaling, mainly by driving changes in aromatase expression the enzyme responsible for estrogen production, and therefore promote tumor formation and progression. There is thus a strong link between adipose inflammation and estrogen biosynthesis and their signaling pathways converge in obese patients. This review describes how obesity-related factors can affect the risk of hormone-dependent breast cancer, highlighting the different molecular mechanisms and metabolic pathways involved in aromatase regulation, estrogen production and breast malignancy in the context of obesity.

The effects of black cohosh on the regulation of estrogen receptor (ERα) and progesterone receptor (PR) in breast cancer cells

The North American plant Cimicifuga racemosa, also known as black cohosh (BC), is a herb that recently has gained attention for its hormonal effects. As the usage of hormone replacement therapy is declining due to its adverse effects in women with cancer, many are turning to herbal remedies like BC to treat menopausal symptoms. It is crucial to determine whether the effects of BC involve estrogen receptor-alpha (ERα). Previous studies from our laboratory have shown ERα to be a possible molecular target for BC. In this study, we examined the effects of BC (8% triterpene glycosides) alone and in combination with hormones and antihormones on the cellular viability, expression of ERα and progesterone receptor (PR)-A/B, and cytolocalization of ERα in ER (+) and PR-A/B (+) T-47D breast cancer cells. Cells were cultured and proteins were extracted and quantified. Western blot analysis revealed alterations in the expression of ERα and PR after treatment with BC (5–100 µM). BC induced a concentration-dependent decrease in ERα and PR protein levels when compared to the control. Image cytometric analysis with propidium iodide staining was used to enumerate changes in T-47D cell number and viability. A decrease in T-47D cell viability was observed upon treatment with 5–100 µM BC. The ideal concentration of BC (100 µM) was used in combination with hormones and antihormones in an effort to further understand the possible similarities between this compound and other known effectors of ERα and PR. After a 24-hour concomitant treatment with and/or in combination of BC, estradiol, ICI 182, 780, and Tamoxifen, downregulation of ERα and PR protein levels was observed. Delineating the role of BC in the regulation of ERα, PR, as well as its mechanisms of action, may be important in understanding the influence of BC on hormone receptors in breast cancer.