Estrogens and progesterone promote persistent CCND1 gene activation during G1 by inducing transcriptional derepression via c-Jun/c-Fos/estrogen receptor (progesterone receptor) complex assembly to a distal regulatory element and recruitment of cyclin D1 to its own gene promoter

Hormone Signaling in Breast Development and Cancer

Hormones control normal breast development and function. They also impinge on breast cancer (BC) development and disease progression in direct and indirect ways. The major ovarian hormones, estrogens and progesterone, have long been established as key regulators of mammary gland development in rodents and linked to human disease. However, their roles have been difficult to disentangle because they act on multiple tissues and can act directly and indirectly on different cell types in the breast, and their receptors interact at different levels within the target cell. Estrogens are well-recognized drivers of estrogen receptor-positive (ER+) breast cancers, and the ER is successfully targeted in ER+ disease. The role of progesterone receptor (PR) as a potential target to be activated or inhibited is debated, and androgen receptor (AR) signaling has emerged as a potentially interesting pathway to target on the stage.In this chapter, we discuss hormone signaling in normal breast development and in cancer, with a specific focus on the key sex hormones: estrogen, progesterone, and testosterone. We will highlight the complexities of endocrine control mechanisms at the organismal, tissue, cellular, and molecular levels. As we delve into the mechanisms of action of hormone receptors, their interplay and their context-dependent roles in breast cancer will be discussed. Drawing insights from new preclinical models, we will describe the lessons learned and the current challenges in understanding hormone action in breast cancer.

Exploration of Novel Therapeutic Targets for Breast Carcinoma and Molecular Docking Studies of Anticancer Compound Libraries with Cyclin-dependent Kinase 4/6 (CDK4/6): A Comprehensive Study of Signalling Pathways for Drug Repurposing

AIMS

This study aims to identify and evaluate promising therapeutic proteins and compounds for breast cancer treatment through a comprehensive database search and molecular docking analysis.

BACKGROUND

Breast cancer (BC), primarily originating from the terminal ductal-lobular unit of the breast, is the most prevalent form of cancer globally. In 2020, an estimated 2.3 million new cases were reported, resulting in approximately 685,000 deaths. Mutations in the BRCA1 and BRCA2 genes are well-established in hereditary breast cancer. The identification of effective therapeutic proteins for BC remains a complex and evolving area of research.

OBJECTIVE

This study aims to identify and evaluate promising therapeutic proteins and compounds specific to breast cancer through a comprehensive database search and molecular docking analysis.

METHODS

A rigorous search was conducted within the National Cancer Institute (NCI), NCI Metathesaurus, SIGnaling Network Open Resource (SIGNOR), Human Protein Atlas (HPA), and the Human Phenotype Ontology (HPO) to shortlist proteins linked to BC (CUI C0678222). Recent studies were reviewed to understand the administration of CDK4/6 inhibitors (palbociclib, ribociclib, abemaciclib) combined with endocrine therapy for HR-positive and HER2-negative breast cancer. Anticancer compound libraries available at ZINC and PubChem were analyzed. Compounds were evaluated based on their binding energies with CDK4 protein, a rationally selected druggable target.

RESULTS

Key proteins linked to breast cancer were identified through database searches. Proliferation, apoptosis, and G1/S transition pathways were frequently found dysregulated in breast cancer. ZINC13152284 exhibited the strongest binding energy at -10.9 Kcal/mol, followed by ZINC05492794 with a binding energy of -10.4 Kcal/mol. Preexisting drugs showed lower binding energies with the CDK4 protein.

CONCLUSION

The study highlights the importance of drug repurposing as a strategy for the safe and effective treatment of breast cancer. Synthetic inhibitors often cause severe side effects, emphasizing the need for novel targets and compounds with better therapeutic profiles. Molecular docking identified promising compounds from the ZINC database, suggesting potential new avenues for breast cancer therapy.

Interdependency of estradiol-mediated ERα activation and subsequent PR and GREB1 induction to control cell cycle progression

Various groups of chemicals that we encounter in every-day life are known to disrupt the endocrine system, such as estrogen mimics that can disturb normal cellular development and homeostasis. To understand the effect of estrogen on intracellular protein dynamics and how this relates to cell proliferation, we aimed to develop a quantitative description of transcription factor complexes and their regulation of cell cycle progression in response to estrogenic stimulation. We designed a mathematical model that describes the dynamics of three proteins, GREB1, PR and TFF1, that are transcriptionally activated upon binding of 17β-estradiol (E2) to estrogen receptor alpha (ERα). Calibration of this model to imaging data monitoring the expression dynamics of these proteins in MCF7 cells suggests that transcriptional activation of GREB1 and PR depends on the association of the E2-ERα complex with both GREB1 and PR. We subsequently combined this ER signaling model with a previously published cell cycle model and compared this to quantification of cell cycle durations in MCF7 cells following nuclei tracking based on images segmented with deep neural networks. The resulting model predicts the effect of GREB1 and PR knockdown on cell cycle progression, thus providing mechanistic insight in the molecular interactions between ERα-regulated proteins and their relation to cell cycle progression. Our findings form a valuable basis to further investigate the pharmacodynamics of endocrine disrupting chemicals and their influence on cellular behavior.

A genetic variant in gene NDUFAF4 confers the risk of non-small cell lung cancer by perturbing hsa-miR-215 binding

Hsa-microRNA-215 (hsa-miR-215) plays multiple roles in carcinogenesis through regulating its target genes. Genetic variants in hsa-miR-215 target sites thus may affect hsa-miR-215-mRNA interactions, result in altered expression of target genes and even influence cancer susceptibility. This study aimed to investigate the associations of genetic variants which located in the binding sites of hsa-miR-215 with non-small cell lung cancer (NSCLC) susceptibility in the Chinese population and reveal the potential regulatory mechanism of functional variants in NSCLC development. The candidate genetic variants were predicted and screened through bioinformatics analysis based on the degree of complementarity of hsa-miR-215 sequences. The potential effects of genetic variants on the binding ability of hsa-miR-215 and target genes were also predicted. A case-control study with 932 NSCLC patients and 1036 healthy controls was conducted to evaluate the association of candidate genetic variants with NSCLC susceptibility, and an independent case-control study with 552 NSCLC cases and 571 controls were used to further validate the promising associations. Dual luciferase reporter gene assay was applied to explore the regulation of the genetic variants on transcription activity of target gene. Cell phenotyping experiments in vitro and RNA sequencing (RNA-seq) were then carried out to preliminarily explore the potential regulatory mechanisms of the target genes in NSCLC. A total of five candidate genetic variants located in the binding sites of hsa-miR-215 were screened. The two-stage case-control study showed that a variant rs1854268 A > T, which located in the 3' untranslated (3'UTR) region of NDUFAF4 gene, was associated with decreased risk of NSCLC (additive model, odds ratio [OR] = 0.83, 95% confidence interval [CI]: 0.75-0.92, p < 0.001). Functional annotation displayed that rs1854268 A > T might downregulate the expression of NDUFAF4 by enhancing the binding affinity of hsa-miR-215-5p to NDUFAF4 mRNA. Additionally, transient knockdown of the NDUFAF4 could inhibit lung cancer cell migration and promote lung cancer cell apoptosis. Further RNA-seq analysis revealed that the knockdown of NDUFAF4 may affect NSCLC development by downregulating the nuclear factor kappa B (NF-κB) and phosphoinositide 3 kinase-AKT (PI3K-AKT) signaling pathways. Moreover, the overexpression of CCND1 could partially attenuate the effects of NDUFAF4 knock down on lung cancer cell migration and apoptosis, indicating that CCND1 may be involved in the tumor-promoting effects of NDUFAF4 as a downstream molecule of NDUFAF4 gene. In conclusion, the genetic variant rs1854268 (A > T) on NDUFAF4 confers NSCLC susceptibility by altering the binding affinity of hsa-miR-215-5p, thus regulating the expression of NDUFAF4 and subsequently influencing downstream tumor molecules and pathways such as CCND1, NF kappa B, and PI3K-AKT signaling pathways.

Oncogenic signals prime cancer cells for toxic cell overgrowth during a G1 cell cycle arrest

CDK4/6 inhibitors are remarkable anti-cancer drugs that can arrest tumor cells in G1 and induce their senescence while causing only relatively mild toxicities in healthy tissues. How they achieve this mechanistically is unclear. We show here that tumor cells are specifically vulnerable to CDK4/6 inhibition because during the G1 arrest, oncogenic signals drive toxic cell overgrowth. This overgrowth causes permanent cell cycle withdrawal by either preventing progression from G1 or inducing genotoxic damage during the subsequent S-phase and mitosis. Inhibiting or reverting oncogenic signals that converge onto mTOR can rescue this excessive growth, DNA damage, and cell cycle exit in cancer cells. Conversely, inducing oncogenic signals in non-transformed cells can drive these toxic phenotypes and sensitize the cells to CDK4/6 inhibition. Together, this demonstrates that cell cycle arrest and oncogenic cell growth is a synthetic lethal combination that is exploited by CDK4/6 inhibitors to induce tumor-specific toxicity.

Interactions between genes altered during cardiotoxicity and neurotoxicity in zebrafish revealed using induced network modules analysis

As the manufacturing and development of new synthetic compounds increase to keep pace with the expanding global demand, adverse health effects due to these compounds are emerging as critical public health concerns. Zebrafish have become a prominent model organism to study toxicology due to their genomic similarity to humans, optical clarity, well-defined developmental stages, short generation time, and cost-effective maintenance. It also provides a shorter time frame for in vivo toxicology evaluation compared to the mammalian experimental systems. Here, we used meta-analysis to examine the alteration in genes during cardiotoxicity and neurotoxicity in zebrafish, caused by chemical exposure of any kind. First, we searched the literature comprehensively for genes that are altered during neurotoxicity and cardiotoxicity followed by meta-analysis using ConsensusPathDB. Since constant communication between the heart and the brain is an important physiological phenomenon, we also analyzed interactions among genes altered simultaneously during cardiotoxicity and neurotoxicity using induced network modules analysis in ConsensusPathDB. We observed inflammation and regeneration as the major pathways involved in cardiotoxicity and neurotoxicity. A large number of intermediate genes and input genes anchored in these pathways are molecular regulators of cell cycle progression and cell death and are implicated in tumor manifestation. We propose potential predictive biomarkers for neurotoxicity and cardiotoxicity and the major pathways potentially implicated in the manifestation of a particular toxicity phenotype.

Glyphosate mimics 17β-estradiol effects promoting estrogen receptor alpha activity in breast cancer cells

Glyphosate, the active ingredient in several broad-spectrum herbicide formulations, has been validated and widely used throughout the world. Recent reports have questioned its safety, showing that glyphosate may act as an endocrine disruptor by promoting estrogenic activity. However, the molecular mechanism involved in this phenomenon remains unclear. Therefore, here we aimed to elucidate the mechanism by which glyphosate induces estrogenic activity using estrogen-sensitive breast cancer cell line models. Our results show that glyphosate mimics the cell effects of 17β-estradiol (E2), promoting estrogen receptor α (ERα) phosphorylation, its degradation, and transcriptional activity at high concentrations. The molecular mechanism seems involved in the ERα ligand-binding domain (LBD). Molecular simulations suggest a plausible interaction between glyphosate and the LBD through a coordinated complex involving divalent cations such as Zn (II). In addition, glyphosate exposure alters the level of Cyclin-dependent kinase 7 that contribute to ERα phosphorylation. Finally, glyphosate increases cell proliferation rate and levels of cell cycle regulators, accompanied by an increase in anchorage-independent growth capacity. These findings suggest that glyphosate at high concentrations, induces estrogen-like effects through an ERα ligand binding site-dependent mechanism, leading to cellular responses resulting from a complex interplay of genomic and non-genomic events.

Umbilical cord mesenchymal stem cells and breast cancer: a good therapeutic candidate or not? A minireview

Breast cancer (BC), as the most common cancer among women, affects a great number of subjects around the world. This heterogenic disease is divided into several types and subtypes, and each subtype has various phenotypes and genotypes. Against BC, several options have been proposed, such as surgery, radiotherapy, and chemotherapeutic agents. However, these approaches may have detrimental effects on health and life quality of patients. Hence, harnessing a therapeutic tool with high effectiveness and low side effects is required. Recently, mesenchymal stem cells (MSCs) have created a new window to treat various disorders, like cancer, and among these, umbilical cord (UC)-derived MSCs have acquired much interest due to their advantages. Therefore, in this narrative review, the influences of UC-derived MSCs on BC were reviewed and summarized with a focus on the molecular mechanisms involved in its pathogenesis and treatment.

Wnt Signaling in the Breast: From Development to Disease

The Wnt cascade is a primordial developmental signaling pathway that plays a myriad of essential functions throughout development and adult homeostasis in virtually all animal species. Aberrant Wnt activity is implicated in embryonic and tissue morphogenesis defects, and several diseases, most notably cancer. The role of Wnt signaling in mammary gland development and breast cancer initiation, maintenance, and progression is far from being completely understood and is rather shrouded in controversy. In this review, we dissect the fundamental role of Wnt signaling in mammary gland development and adult homeostasis and explore how defects in its tightly regulated and intricated molecular network are interlinked with cancer, with a focus on the breast.

Prognostic and Predictive Value of CCND1/Cyclin D1 Amplification in Breast Cancer With a Focus on Postmenopausal Patients: A Systematic Review and Meta-Analysis

BACKGROUND

Up to 80% of breast cancers (BCa) are estrogen receptor positive and current treatments target the estrogen receptor (endocrine therapies) and/or CDK4/6 (CDK4/6 inhibitors). CCND1 encodes the protein cyclin D1, responsible for regulation of G1 to S phase transition in the cell cycle. CCND1 amplification is common in BCa and contributes to increased cyclin D1 expression. As there are signalling interactions between cyclin D1 and the estrogen receptor, understanding the impact of CCND1 amplification on estrogen receptor positive patients' disease outcomes, is vital. This review aims to evaluate CCND1 amplification as a prognostic and predictive biomarker in BCa.

MATERIALS AND METHODS

Publications were retrieved from the databases: PubMed, MEDLINE, Embase and Cochrane library. Exclusion criteria were duplication, publication type, non-English language, in vitro and animal studies, not BCa, male BCa, premenopausal BCa, cohort size <35, CCND1 amplification not reported. Publications with cohort duplication, and inadequate recurrence free survival (RFS) and overall survival (OS) data, were also excluded. Included publications were assessed for Risk of Bias (RoB) using the Quality In Prognosis Studies tool. Statistical analyses (Inverse Variance and Mantel-Haenszel) were performed in Review Manager. The PROSPERO registration number is [CRD42020208179].

RESULTS

CCND1 amplification was significantly associated with positive estrogen receptor status (OR:1.70, 95% CI:1.19-2.43, p = 0.004) and cyclin D1 overexpression (OR: 5.64, 95% CI: 2.32-13.74, p=0.0001). CCND1 amplification was significantly associated with shorter RFS (OR: 1.64, 95% CI: 1.13-2.38, p = 0.009), and OS (OR: 1.51, 95% CI: 1.19-1.92, p = 0.0008) after removal of studies with a high RoB. In endocrine therapy treated patients specifically, CCND1 amplification predicted shorter RFS (HR: 2.59, 95% CI: 1.96-3.41, p < 0.00001) and OS (HR: 1.59, 95% CI: 1.00-2.49, p = 0.05) also after removal of studies with a high RoB.

CONCLUSION

While a lack of standardised approach for the detection of CCND1 amplification is to be considered as a limitation, CCND1 amplification was found to be prognostic of shorter RFS and OS in BCa. CCND1 amplification is also predictive of reduced RFS and OS in endocrine therapy treated patients specifically. With standardised methods and cut offs for the detection of CCND1 amplification, CCND1 amplification would have potential as a predictive biomarker in breast cancer patients.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/, identifier CRD42020208179.

NAP1L1 interacts with hepatoma-derived growth factor to recruit c-Jun inducing breast cancer growth

BACKGROUND

Breast cancer is a common cancer among women in the world. However, its pathogenesis is still to be determined. The role and molecular mechanism of Nucleosome Assembly Protein 1 Like 1 (NAP1L1) in breast cancer have not been reported. Elucidation of molecular mechanism might provide a novel therapeutic target for breast cancer treatment.

METHODS

A bioinformatics analysis was conducted to determine the differential expression of NAP1L1 in breast cancer and find the potential biomarker that interacts with NAP1L1 and hepatoma-derived growth factor (HDGF). The expression of NAP1L1 in tissues was detected by using immunohistochemistry. Breast cancer cells were transfected with the corresponding lentiviral particles and siRNA. The efficiency of transfection was measured by RT-qPCR and western blotting. Then, MTT, Edu, plate clone formation, and subcutaneous tumorigenesis in nude mice were used to detect the cell proliferation in breast cancer. Furthermore, coimmunoprecipitation (Co-IP) assay and confocal microscopy were performed to explore the detailed molecular mechanism of NAP1L1 in breast cancer.

RESULTS

In this study, NAP1L1 protein was upregulated based on the Clinical Proteomic Tumor Analysis Consortium (CPTAC) database. Consistent with the prediction, immunohistochemistry staining showed that NAP1L1 protein expression was significantly increased in breast cancer tissues. Its elevated expression was an unfavorable factor for breast cancer clinical progression and poor prognosis. Stably or transiently knocking down NAP1L1 reduced the cell growth in vivo and in vitro via repressing the cell cycle signal in breast cancer. Furthermore, the molecular basis of NAP1L1-induced cell cycle signal was further studied. NAP1L1 interacted with the HDGF, an oncogenic factor for tumors, and the latter subsequently recruited the key oncogenic transcription factor c-Jun, which finally induced the expression of cell cycle promoter Cyclin D1(CCND1) and thus the cell growth of breast cancer.

CONCLUSIONS

Our data demonstrated that NAP1L1 functions as a potential oncogene via interacting with HDGF to recruit c-Jun in breast cancer.

Nuclear Receptor-Mediated Metabolic Reprogramming and the Impact on HR+ Breast Cancer

Simple Summary

Breast cancer is the most commonly diagnosed and second leading cause of cancer-related deaths in women in the United States, with hormone receptor positive (HR+) tumors representing more than two-thirds of new cases. Recent evidence has indicated that dysregulation of multiple metabolic programs, which can be driven through nuclear receptor activity, is essential for tumor genesis, progression, therapeutic resistance and metastasis. This study will review the current advances in our understanding of the impact and implication of altered metabolic processes driven by nuclear receptors, including hormone-dependent signaling, on HR+ breast cancer.

Abstract

Metabolic reprogramming enables cancer cells to adapt to the changing microenvironment in order to maintain metabolic energy and to provide the necessary biological macromolecules required for cell growth and tumor progression. While changes in tumor metabolism have been long recognized as a hallmark of cancer, recent advances have begun to delineate the mechanisms that modulate metabolic pathways and the consequence of altered signaling on tumorigenesis. This is particularly evident in hormone receptor positive (HR+) breast cancers which account for approximately 70% of breast cancer cases. Emerging evidence indicates that HR+ breast tumors are dependent on multiple metabolic processes for tumor progression, metastasis, and therapeutic resistance and that changes in metabolic programs are driven, in part, by a number of key nuclear receptors including hormone-dependent signaling. In this review, we discuss the mechanisms and impact of hormone receptor mediated metabolic reprogramming on HR+ breast cancer genesis and progression as well as the therapeutic implications of these metabolic processes in this disease.

Steroid Receptors in Breast Cancer: Understanding of Molecular Function as a Basis for Effective Therapy Development

Breast cancer remains one of the most important health problems worldwide. The family of steroid receptors (SRs), which comprise estrogen (ER), progesterone (PR), androgen (AR), glucocorticoid (GR) and mineralocorticoid (MR) receptors, along with a receptor for a secosteroid-vitamin D, play a crucial role in the pathogenesis of the disease. They function predominantly as nuclear receptors to regulate gene expression, however, their full spectrum of action reaches far beyond this basic mechanism. SRs are involved in a vast variety of interactions with other proteins, including extensive crosstalk with each other. How they affect the biology of a breast cell depends on such factors as post-translational modifications, expression of coregulators, or which SR isoform is predominantly synthesized in a given cellular context. Although ER has been successfully utilized as a breast cancer therapy target for years, research on therapeutic application of other SRs is still ongoing. Designing effective hormone therapies requires thorough understanding of the molecular function of the SRs. Over the past decades, huge amount of data was obtained in multiple studies exploring this field, therefore in this review we attempt to summarize the current knowledge in a comprehensive way.

Oestrogen receptor activity in hormone-dependent breast cancer during chemotherapy

Background

Chemotherapy efficacy in early-stage hormone receptor-positive (HR+) breast cancer (BC) according to menopausal status needs a biological explanation.

Methods

We compared early-stage HR+ BC biological features before and after (neo)adjuvant chemotherapy or endocrine therapy (ET), and assessed oestrogen receptor (ER) pathway activity in both pre- and post-menopausal patients. The nCounter platform was used to detect gene expression levels.

Findings

In 106 post-menopausal patients with HR+/HER2-negative BC randomized to neoadjuvant chemotherapy or ET (letrozole+ribociclib), a total of 19 oestrogen-regulated genes, including progesterone receptor (PGR), were found downregulated in the ET-based arm-only. We confirmed this finding in an independent dataset of 20 letrozole-treated post-menopausal patients and found, conversely, an up-regulation of the same signature in HR+/HER2-negative MCF7 cell line treated with estradiol. PGR was found down-regulated by 2 weeks of ET+anti-HER2 therapy in pre-/post-menopausal patients with HR+/HER2-positive (HER2+) BC, while anti-HER2 therapy alone increased PGR expression in HR-negative/HER2+ BC. In 88 pre- and post-menopausal patients with newly diagnosed HR+/HER2-negative BC treated with chemotherapy, the 19 oestrogen-regulated genes were found significantly downregulated only in pre-menopausal patients. In progesterone receptor (PR)+/HER2-negative BC treated with neoadjuvant chemotherapy (n=40), tumours became PR-negative in 69.2% of pre-menopausal patients and 14.8% of post-menopausal patients (p=0.001). Finally, a mean decrease in PGR levels was only observed in pre-menopausal patients undergoing anti-HER2-based multi-agent chemotherapy.

Interpretation

Chemotherapy reduces the expression of ER-regulated genes in pre-menopausal women suffering from hormone-dependent BC by supressing ovarian function. Further studies should test the value of chemotherapy in this patient population when ovarian function is suppressed by other methods.

Funding

Instituto de Salud Carlos III, Breast Cancer Now, the Breast Cancer Research Foundation, the American Association for Cancer Research, Fundació La Marató TV3, the European Union's Horizon 2020 Research and Innovation Programme, Pas a Pas, Save the Mama, Fundación Científica Asociación Española Contra el Cáncer, PhD4MDgrant of “Departament de Salut”, exp SLT008/18/00122, Fundación SEOM and ESMO. Any views, opinions, findings, conclusions, or recommendations expressed in this material are those solely of the author(s).

Physiologically Relevant Estrogen Receptor Alpha Pathway Reporters for Single-Cell Imaging-Based Carcinogenic Hazard Assessment of Estrogenic Compounds

Estrogen receptor alpha (ERα) belongs to the nuclear hormone receptor family of ligand-inducible transcription factors and regulates gene networks in biological processes such as cell growth and proliferation. Disruption of these networks by chemical compounds with estrogenic activity can result in adverse outcomes such as unscheduled cell proliferation, ultimately culminating in tumor formation. To distinguish disruptive activation from normal physiological responses, it is essential to quantify relationships between different key events leading to a particular adverse outcome. For this purpose, we established fluorescent protein MCF7 reporter cell lines for ERα-induced proliferation by bacterial artificial chromosome-based tagging of 3 ERα target genes: GREB1, PGR, and TFF1. These target genes are inducible by the non-genotoxic carcinogen and ERα agonist 17β-estradiol in an ERα-dependent manner and are essential for ERα-dependent cell-cycle progression and proliferation. The 3 GFP reporter cell lines were characterized in detail and showed different activation dynamics upon exposure to 17β-estradiol. In addition, they demonstrated specific activation in response to other established reference estrogenic compounds of different potencies, with similar sensitivities as validated OECD test methods. This study shows that these fluorescent reporter cell lines can be used to monitor the spatial and temporal dynamics of ERα pathway activation at the single-cell level for more mechanistic insight, thereby allowing a detailed assessment of the potential carcinogenic activity of estrogenic compounds in humans.

CBP-JMF: An Improved Joint Matrix Tri-Factorization Method for Characterizing Complex Biological Processes of Diseases

Multi-omics molecules regulate complex biological processes (CBPs), which reflect the activities of various molecules in living organisms. Meanwhile, the applications to represent disease subtypes and cell types have created an urgent need for sample grouping and associated CBP-inferring tools. In this paper, we present CBP-JMF, a practical tool primarily for discovering CBPs, which underlie sample groups as disease subtypes in applications. Differently from existing methods, CBP-JMF is based on a joint non-negative matrix tri-factorization framework and is implemented in Python. As a pragmatic application, we apply CBP-JMF to identify CBPs for four subtypes of breast cancer. The result shows significant overlapping between genes extracted from CBPs and known subtype pathways. We verify the effectiveness of our tool in detecting CBPs that interpret subtypes of disease.

Expression of Estrogen Receptor- and Progesterone Receptor-Regulating MicroRNAs in Breast Cancer

In ~70% of breast cancer (BC) cases, estrogen and progesterone receptors (ER and PR) are overexpressed, which can change during tumor progression. Expression changes of these receptors during cancer initiation and progression can be caused by alterations in microRNA (miR, miRNA) expression. To assess the association of BC progression with aberrant expression of miRNAs that target ER and PR mRNAs, we quantified miR-19b, -222, -22, -378a, and -181a in BC samples (n = 174) by real-time PCR. Underexpression of miR-222 and miR-378a in stage T2–T4 BC was characteristic for HER2-overexpressing tumors. In addition, the expression of miR-181a and miR-378a was higher in these tumors than in tumors with a HER2 IHC score of 0 or 1+. In tumors with a Ki-67 index ≥ 14%, all tested miRNAs were underexpressed in BC with a high Allred PR score (6–8). In ER-and-PR–negative tumors, miR-22, miR-222, miR-181a, and miR-378a underexpression was associated with Ki-67 index > 35% (median value). MiR-19b and miR-22 underexpression could be a marker of lymph node metastasis in ER- and/or PR-positive tumors with HER2 IHC score 0. Thus, the association of miR-19b, miR-22, miR-222, miR-378a, and miR-181a levels with BC characteristics is influenced by the status of tumor ER, PR, HER2, and Ki-67.

Expression of estrogen-, progesterone-, and androgen-responsive genes in MCF-7 and MDA-MB-231 cells treated with o,p'-DDT, p,p'-DDT, or endosulfan

Endocrine disruptors are a major concern due to their possible association with hormone-dependent carcinogenesis. Some examples of compounds with such properties are organochlorine pesticides (OCPs). OCPs are persistent pollutants with high lipophilicity, long half-life, and bioaccumulation potential. In the past, some of the most commonly used OCPs were dichlorodiphenyltrichloroethane (DDT) and endosulfan. Here, we investigated the effects of o,p'-DDT, p,p'-DDT, and endosulfan and of hormones estradiol, testosterone, and progesterone on the expression of estrogen, progesterone, and androgen receptors (ER, PR, and AR) and of their target genes (KLF4, VEGFA, CCND1, PRLR, CDKN1A, and BCL6) in MCF-7 and MDA-MB-231 cells. The results confirmed that under the action of the insecticides, there are dose- and time-dependent changes in the expression of these receptors and target genes. As corroborated by an experiment with ER, PR, and AR negative MDA-MB-231 cells, the change in the expression of KLF4, VEGFA, CCND1, and PRLR in MCF-7 cells treated with o,p'-DDT and the change in CDKN1A and PRLR expression in MCF-7 cells treated with p,p'-DDT are likely mediated by ER, PR, and AR pathways. In conclusion, we have identified some targets of DDT and endosulfan and confirmed that the effects of insecticides on the expression of these target genes differ for breast cancer cell lines with different receptor statuses.

Constitutive expression of progesterone receptor isoforms promotes the development of hormone-dependent ovarian neoplasms

Differences in the relative abundances of the progesterone receptor (PGR) isoforms PGRA and PGRB are often observed in women with reproductive tract cancers. To assess the importance of the PGR isoform ratio in the maintenance of the reproductive tract, we generated mice that overexpress PGRA or PGRB in all PGR-positive tissues. Whereas few PGRA-overexpressing mice developed reproductive tract tumors, all PGRB-overexpressing mice developed ovarian neoplasms that were derived from ovarian luteal cells. Transcriptomic analyses of the ovarian tumors from PGRB-overexpressing mice revealed enhanced AKT signaling and a gene expression signature similar to those of human ovarian and endometrial cancers. Treating PGRB-overexpressing mice with the PGR antagonist RU486 stalled tumor growth and decreased the expression of cell cycle-associated genes, indicating that tumor growth and cell proliferation were hormone dependent in addition to being isoform dependent. Analysis of the PGRB cistrome identified binding events at genes encoding proteins that are critical regulators of mitotic phase entry. This work suggests a mechanism whereby an increase in the abundance of PGRB relative to that of PGRA drives neoplasia in vivo by stimulating cell cycling.

Progesterone receptor membrane component 1 is required for mammary gland development†

The physiological functions of progesterone (P4) in female reproductive organs including the mammary glands are mediated via the progesterone receptor (PR), but not all P4 functions can be explained by PR-mediated signaling. Progesterone receptor membrane component 1 (PGRMC1), a potential mediator of P4 actions, plays an important role in the ovary and uterus in maintaining female fertility and pregnancy, but its function in mammary glands has not been elucidated. This study investigated the role of PGRMC1 in mouse mammary gland development. Unlike in the uterus, exogenous estrogen (E2) and/or P4 did not alter PGRMC1 expression in the mammary gland, and Pgrmc1-knockout (KO) mice displayed reduced ductal elongation and side branching in response to hormone treatment. During pregnancy, PGRMC1 was expressed within both the luminal and basal epithelium and gradually increased with gestation and decreased rapidly after parturition. Moreover, although lactogenic capacity was normal after parturition, Pgrmc1 KO resulted in defective mammary gland development from puberty until midpregnancy, while the expression of PR and its target genes was not significantly different between wild-type and Pgrmc1-KO mammary gland. These data suggest that PGRMC1 is essential for mammary gland development during puberty and pregnancy in a PR-independent manner.

Exposure to DEHP or its metabolite MEHP promotes progesterone secretion and inhibits proliferation in mouse placenta or JEG-3 cells

Di (2-ethyl-hexyl)phthalate (DEHP) is an environmental endocrine disruptor and commonly used as plasticizer. Maternal DEHP exposure during pregnancy reduces placental size and destroys placental structure. However, the underlying mechanisms were unclear. In this study, we supposed that DEHP disturbs endocrine function of placenta to inhibit the proliferation of placental cell. Using radioimmunoassay and ELISA, we found that DEHP and its active metabolite mono (2-ethyl-hexyl) phthalate (MEHP) promoted progesterone secretion in pregnant mouse and in JEG-3 cells, respectively. Therefore, placental endocrine function was altered by DEHP. The mRNA and protein level of progesterone synthetase 3β-HSD1 was elevated by DEHP, which is conducive to the synthesis of progesterone. The level of progesterone receptor was down-regulated by DEHP and MEHP in mouse placenta and in JEG-3 cells, respectively. PR deficiency further promoted the level of 3β-HSD1, which leads to a higher progesterone level. In turn, higher concentration of progesterone further inhibited the expression of PGR (PR gene). Therefore, higher progesterone down-regulated the level of its receptor PR. Meanwhile, decreased PR induced more progesterone secretion. There is a feedback loop between progesterone and PR. PR deficiency down-regulated the protein level of Cyclin D1 which plays an important role in cell proliferation. Accordingly, DEHP and its active metabolite MEHP can restrain proliferation of placental cell and disturb the progesterone secretion via decreasing the level of PR.

Molecular mechanisms underlying progesterone receptor action in breast cancer: Insights into cell proliferation and stem cell regulation

The ovarian steroid hormone progesterone and its nuclear receptor, the Progesterone Receptor (PR), play an essential role in the regulation of cell proliferation and differentiation in the mammary gland. In addition, experimental and clinical evidence demonstrate their critical role in controlling mammary gland tumorigenesis and breast cancer development. When bound to its ligand, the main action of PR is as a transcription factor, which regulates the expression of target genes networks. PR also activates signal transduction pathways through a rapid or non-genomic mechanism in breast cancer cells, an event that is fully integrated with its genomic effects. This review summarizes the molecular mechanisms of the ligand-activated PR actions that drive epithelial cell proliferation and the regulation of the stem cell population in the normal breast and in breast cancer.

Equol Pretreatment Protection of SH-SY5Y Cells against Aβ (25-35)-Induced Cytotoxicity and Cell-Cycle Reentry via Sustaining Estrogen Receptor Alpha Expression

β-amyloid formation in the brain is one of the characteristics of Alzheimer’s disease. Exposure to this peptide may result in reentry into the cell cycle leading to cell death. The phytoestrogen equol has similar biological effects as estrogen without the side effects. This study investigated the possible mechanism of the neuron cell-protecting effect of equol during treatment with Aβ. SH-SY5Y neuroblastoma cells were treated with either 1 μM S-equol or 10 nM 17β-estradiol for 24 h prior to 1 μM Aβ (25–35) exposure. After 24 h exposure to Aβ (25–35), a significant reduction in cell survival and a reentry into the cell cycle process accompanied by increased levels of cyclin D1 were observed. The expressions of estrogen receptor alpha (ERα) and its coactivator, steroid receptor coactivator-1 (SRC-1), were also significantly downregulated by Aβ (25–35) in parallel with activated extracellular signal-regulated kinase (ERK)1/2. However, pretreatment of cells with S-equol or 17β-estradiol reversed these effects. Treatment with the ER antagonist, ICI-182,780 (1 μM), completely blocked the effects of S-equol and 17β-estradiol on cell viability, ERα, and ERK1/2 after Aβ (25–35) exposure. These data suggest that S-equol possesses a neuroprotective potential as it effectively antagonizes Aβ (25–35)-induced cell cytotoxicity and prevents cell cycle reentry in SH-SY5Y cells. The mechanism underlying S-equol neuroprotection might involve ERα-mediated pathways.

Yin Yang 1 Suppresses Dilated Cardiomyopathy and Cardiac Fibrosis Through Regulation of Bmp7 and Ctgf

RATIONALE

Pathogenic variations in the lamin gene (LMNA) cause familial dilated cardiomyopathy (DCM). LMNA insufficiency caused by LMNA pathogenic variants is believed to be the basic mechanism underpinning LMNA-related DCM.

OBJECTIVE

To assess whether silencing of cardiac Lmna causes DCM and investigate the role of Yin Yang 1 (Yy1) in suppressing Lmna DCM.

METHODS AND RESULTS

We developed a Lmna DCM mouse model induced by cardiac-specific Lmna short hairpin RNA. Silencing of cardiac Lmna induced DCM with associated cardiac fibrosis and inflammation. We demonstrated that upregulation of Yy1 suppressed Lmna DCM and cardiac fibrosis by inducing Bmp7 expression and preventing upregulation of Ctgf. Knockdown of upregulated Bmp7 attenuated the suppressive effect of Yy1 on DCM and cardiac fibrosis. However, upregulation of Bmp7 alone was not sufficient to suppress DCM and cardiac fibrosis. Importantly, upregulation of Bmp7 together with Ctgf silencing significantly suppressed DCM and cardiac fibrosis. Mechanistically, upregulation of Yy1 regulated Bmp7 and Ctgf reporter activities and modulated Bmp7 and Ctgf gene expression in cardiomyocytes. Downregulation of Ctgf inhibited TGF-β (transforming growth factor-β)/Smad signaling in DCM hearts. Regulation of both Bmp7 and Ctgf further suppressed TGFβ/Smad signaling. In addition, co-modulation of Bmp7 and Ctgf reduced CD3+ T cell numbers in DCM hearts.

CONCLUSIONS

Our findings demonstrate that upregulation of Yy1 or co-modulation of Bmp7 and Ctgf offer novel therapeutic strategies for the treatment of DCM caused by LMNA insufficiency.

Fulvestrant in management of hormone receptor-positive metastatic breast cancer

Fulvestrant is a steroidal selective estrogen receptor degrader that was approved by the US FDA in 2002 for treatment of ER-positive metastatic breast cancer (ER + MBC) post-progression on aromatase inhibitors. In 2017, the label was updated to include endocrine therapy naive ER + MBC. While initially fulvestrant was thought to be equivalent to aromatase inhibitors with monthly dose of 250 mg intramuscular injection, several postmarketing trials challenged this understanding. Subsequently, the recommended dose changed to 500 mg monthly plus loading dose, and this was proven to be superior to anastrozole in efficacy. Most recently the results of FALCON trial have further challenged the way fulvestrant is viewed and used. This report provides a historical perspective on this compound, its evolving role in management of ER + MBC and what the future may hold for this drug.

Breast cancer development and progression: Risk factors, cancer stem cells, signaling pathways, genomics, and molecular pathogenesis

As the most commonly occurring cancer in women worldwide, breast cancer poses a formidable public health challenge on a global scale. Breast cancer consists of a group of biologically and molecularly heterogeneous diseases originated from the breast. While the risk factors associated with this cancer varies with respect to other cancers, genetic predisposition, most notably mutations in BRCA1 or BRCA2 gene, is an important causative factor for this malignancy. Breast cancers can begin in different areas of the breast, such as the ducts, the lobules, or the tissue in between. Within the large group of diverse breast carcinomas, there are various denoted types of breast cancer based on their invasiveness relative to the primary tumor sites. It is important to distinguish between the various subtypes because they have different prognoses and treatment implications. As there are remarkable parallels between normal development and breast cancer progression at the molecular level, it has been postulated that breast cancer may be derived from mammary cancer stem cells. Normal breast development and mammary stem cells are regulated by several signaling pathways, such as estrogen receptors (ERs), HER2, and Wnt/β-catenin signaling pathways, which control stem cell proliferation, cell death, cell differentiation, and cell motility. Furthermore, emerging evidence indicates that epigenetic regulations and noncoding RNAs may play important roles in breast cancer development and may contribute to the heterogeneity and metastatic aspects of breast cancer, especially for triple-negative breast cancer. This review provides a comprehensive survey of the molecular, cellular and genetic aspects of breast cancer.

Revisiting progesterone receptor (PR) actions in breast cancer: Insights into PR repressive functions

Progesterone receptor (PR) is a master regulator in female reproductive tissues that controls developmental processes and proliferation and differentiation during the reproductive cycle and pregnancy. PR also plays a role in progression of endocrine-dependent breast cancer. As a member of the nuclear receptor family of ligand-dependent transcription factors, the main action of PR is to regulate networks of target gene expression in response to binding its cognate steroid hormone, progesterone. Liganded-PR transcriptional activation has been thoroughly studied and associated mechanisms have been described while progesterone-mediated repression has remained less explored. The present work summarizes recent advances in the understanding of how PR-mediated repression is accomplished in breast cancer cells and highlights the significance of fully understanding the determinants of context-dependent PR action.

YY1 Positively Regulates Transcription by Targeting Promoters and Super-Enhancers through the BAF Complex in Embryonic Stem Cells

Yin Yang 1 (YY1) regulates early embryogenesis and adult tissue formation. However, the role of YY1 in stem cell regulation remains unclear. YY1 has a Polycomb group (PcG) protein-dependent role in mammalian cells. The PcG-independent functions of YY1 are also reported, although their underlying mechanism is still undefined. This paper reports the role of YY1 and BAF complex in the OCT4-mediated pluripotency network in mouse embryonic stem cells (mESCs). The interaction between YY1 and BAF complex promotes mESC proliferation and pluripotency. Knockdown of Yy1 or Smarca4, the core component of the BAF complex, downregulates pluripotency markers and upregulates several differentiation markers. Moreover, YY1 enriches at both promoter and super-enhancer regions to stimulate transcription. Thus, this study elucidates the role of YY1 in regulating pluripotency through its interaction with OCT4 and the BAF complex and the role of BAF complex in integrating YY1 into the core pluripotency network.

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YY1 is integrated into the core pluripotency network through the BAF complex

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YY1 and the BAF complex promote ESC proliferation

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YY1 activates gene expression through the BAF complex to maintain pluripotency

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YY1 is enriched at the ESC-specific super-enhancers to promote gene expression

Cyclin D1 promoter -56 and -54bp CpG un-methylation predicts invasive progression in arsenic-induced Bowen's disease

BACKGROUND

Patients with arsenic-induced Bowen's disease (As-BD) are at risk of developing invasive cancers in the skin, lung, and urinary bladder. However, a longitudinal follow-up study on the association between As-BD and invasive cancers is still lacking.

OBJECTIVES

This study aims to investigate the underlying molecular mechanisms of this malignant progression in the skin and internal organs.

METHODS

This is a biopsy-based follow-up study. We tested the DNA histograms, Cyclin D1 (CCND1) protein expression and CCND1 promoter DNA methylation in 40 pathologically confirmed specimens from As-BD patients to correlate with individual's invasive cancer occurrence in the 5-year follow-up.

RESULTS

Flow cytometric DNA histogram analysis of skin specimens showed aneuploid (n=15), G2/M arrest (n=22), and normal (n=3) DNA histograms. No patients with normal DNA histograms developed invasive cancers, whereas 13 developed invasive cancers in the aneuploid group and 2 developed invasive cancers in the G2/M arrest group. The aneuploid group showed a high risk of invasive cancer development. In all assessed aneuploid specimens, the CCND1 promoter hypomethylation was observed. Statistically, percentage of un-methylation more than 55.85% among 17 detected CpG sites showed extremely high predictive power in the occurrence of invasive arsenical cancers. Furthermore, the un-methylation at -56 and -54bp CpG sites was statistically significantly associated with invasive arsenical cancer development (p=1.29×10^-5).

CONCLUSIONS

As-BD lesions showing an aneuploid DNA histogram had a high risk of invasive cancer development. Un-methyaltion at -56 and -54bp CpG in the CCND1 promoter serves as a predictor for invasive progression in As-BD patients.

Suppression of LETM1 by siRNA inhibits cell proliferation and invasion of bladder cancer cells

The leucine zipper-EF-hand containing transmembrane protein 1 (LETM1) is highly expressed in many human malignancies and is correlated with poor prognosis. However, the function of LETM1 in bladder cancer still remains unknown. In the present study, we analyzed the expression levels of LETM1 in bladder cancer tissues and non-cancerous tissues as well as in four bladder cancer cell lines (T24, EJ, 5637 and J82) and a human bladder epithelial immortalized cell line SV-HUC-1. Small interfering RNA (siRNA) was employed to knockdown the expression of LETM1 in the T24 cells. The proliferation of T24 cells was significantly repressed as evaluated by CCK-8 assays. Transwell migration and invasion assays indicated that knockdown of LETM1 suppressed cell migration and invasion significantly. Flow cytometric analysis revealed that cells had accumulated at the S-phase when the expression of LETM1 was suppressed. Moreover, we found that several oncogenic proteins in the Wnt/β-catenin signaling pathway, namely β-catenin, cyclin D1 and c-Myc were significantly decreased by the LETM1 siRNA. Collectively, these results revealed that the knockdown of LETM1 exhibited tumor suppressive effects, possibly by controlling the downstream Wnt/β-catenin signaling pathway.

JMJD2A promotes the Warburg effect and nasopharyngeal carcinoma progression by transactivating LDHA expression

BACKGROUND

Jumonji C domain 2A (JMJD2A), as a histone demethylases, plays a vital role in tumorigenesis and progression. But, its functions and underlying mechanisms of JMJD2A in nasopharyngeal carcinoma (NPC) metabolism are remained to be clarified. In this study, we investigated glycolysis regulation by JMJD2A in NPC and the possible mechanism.

METHODS

JMJD2A expression was detected by Western blotting and Reverse transcription quantitative real-time PCR analysis. Then, we knocked down and ectopically expressed JMJD2A to detect changes in glycolytic enzymes. We also evaluated the impacts of JMJD2A-lactate dehydrogenase A (LDHA) signaling on NPC cell proliferation, migration and invasion. ChIP assays were used to test whether JMJD2A bound to the LDHA promoter. Finally, IHC was used to verify JMJD2A and LDHA expression in NPC tissue samples and analyze their correlation between expression and clinical features.

RESULTS

JMJD2A was expressed at high levels in NPC tumor tissues and cell lines. Both JMJD2A and LDHA expression were positively correlated with the tumor stage, metastasis and clinical stage. Additionally, the level of JMJD2A was positively correlated with LDHA expression in NPC patients, and higher JMJD2A and LDHA expression predicted a worse prognosis. JMJD2A alteration did not influence most of glycolytic enzymes expression, with the exception of PFK-L, PGAM-1, LDHB and LDHA, and LDHA exhibited the greatest decrease in expression. JMJD2A silencing decreased LDHA expression and the intracellular ATP level and increased LDH activity, lactate production and glucose utilization, while JMJD2A overexpression produced the opposite results. Furthermore, JMJD2A could combine to LDHA promoter region and regulate LDHA expression at the level of transcription. Activated JMJD2A-LDHA signaling pathway promoted NPC cell proliferation, migration and invasion.

CONCLUSIONS

JMJD2A regulated aerobic glycolysis by regulating LDHA expression. Therefore, the novel JMJD2A-LDHA signaling pathway could contribute to the Warburg effects in NPC progression.

HDAC1, HDAC4, and HDAC9 Bind to PC3/Tis21/Btg2 and Are Required for Its Inhibition of Cell Cycle Progression and Cyclin D1 Expression

PC3/Tis21 is a transcriptional cofactor that inhibits proliferation in several cell types, including neural progenitors. Here, we report that PC3/Tis21 associates with HDAC1, HDAC4, and HDAC9 in vivo, in fibroblast cells. Furthermore, when HDAC1, HDAC4, or HDAC9 are silenced in fibroblasts or in a line of cerebellar progenitor cells, the ability of PC3/Tis21 to inhibit proliferation is significantly reduced. Overexpression of HDAC1, HDAC4, or HDAC9 in fibroblasts and in cerebellar precursor cells synergizes with PC3/Tis21 in inhibiting the expression of cyclin D1, a cyclin selectively inhibited by PC3/Tis21. Conversely, the depletion of HDAC1 or HDAC4 (but not HDAC9) in fibroblasts and in cerebellar precursor cells significantly impairs the ability of PC3/Tis21 to inhibit cyclin D1 expression. An analysis of HDAC4 deletion mutants shows that both the amino-terminal moiety and the catalytic domain of HDAC4 associate to PC3/Tis21, but neither alone is sufficient to potentiate the inhibition of cyclin D1 by PC3/Tis21. As a whole, our findings indicate that PC3/Tis21 inhibits cell proliferation in a way dependent on the presence of HDACs, in fibroblasts as well as in neural cells. Considering that several reports have demonstrated that HDACs can act as transcriptional corepressors on the cyclin D1 promoter, our data suggest that the association of PC3/Tis21 to HDACs is functional to recruit them to target genes, such as cyclin D1, for repression of their expression. J. Cell. Physiol. 232: 1696-1707, 2017. © 2016 Wiley Periodicals, Inc.

Full antagonism of the estrogen receptor without a prototypical ligand side chain

Resistance to endocrine therapies remains a major clinical problem for the treatment of estrogen receptor-α (ERα)-positive breast cancer. On-target side effects limit therapeutic compliance and use for chemoprevention, highlighting an unmet need for new therapies. Here we present a full-antagonist ligand series lacking the prototypical ligand side chain that has been universally used to engender antagonism of ERα through poorly understood structural mechanisms. A series of crystal structures and phenotypic assays reveal a structure-based design strategy with separate design elements for antagonism and degradation of the receptor, and access to a structurally distinct space for further improvements in ligand design. Understanding structural rules that guide ligands to produce diverse ERα-mediated phenotypes has broad implications for the treatment of breast cancer and other estrogen-sensitive aspects of human health including bone homeostasis, energy metabolism, and autoimmunity.

Progesterone induces progesterone receptor gene (PGR) expression via rapid activation of protein kinase pathways required for cooperative estrogen receptor alpha (ER) and progesterone receptor (PR) genomic action at ER/PR target genes

Progesterone Receptors (PRs) are critical effectors of estrogen receptor (ER) signaling required for mammary gland development and reproductive proficiency. In breast and reproductive tract malignancies, PR expression is a clinical prognostic marker of ER action. While estrogens primarily regulate PR expression, other factors likely contribute to a dynamic range of receptor expression across diverse tissues. In this study, we identified estrogen-independent but progestin (R5020)-dependent regulation of ER target genes including PGR in ER+/PR+ cancer cell lines. R5020 (10nM-10μM range) induced dose-dependent PR mRNA and protein expression in the absence of estrogen but required both PR and ERα. Antagonists of either PR (RU486, onapristone) or ERα (ICI 182,780) attenuated R5020 induction of TFF1, CTSD, and PGR. Chromatin immunoprecipitation (ChIP) assays performed on ER+/PR+ cells demonstrated that both ERα and PR were recruited to the same ERE/Sp1 site-containing region of the PGR proximal promoter in response to high dose progestin (10μM). Recruitment of ERα and PR to chromatin and subsequent PR mRNA induction were dependent upon rapid activation of MAPK/ERK and AKT; inhibition of these kinase pathways via U0126 or LY294002 blocked these events. Overall, we have identified a novel mechanism of ERα activation initiated by rapid PR-dependent kinase pathway activation and associated with phosphorylation of ERα Ser118 for estrogen-independent but progestin-dependent ER/PR cross talk. These studies may provide insight into mechanisms of persistent ER-target gene expression during periods of hormone (i.e. estrogen) ablation and suggest caution following prolonged treatment with aromatase or CYP17 inhibitors (i.e. contexts when progesterone levels may be abnormally elevated).

Current knowledge of the multifunctional 17β-hydroxysteroid dehydrogenase type 1 (HSD17B1)

At the late 1940s, 17β-HSD1 was discovered as the first member of the 17β-HSD family with its gene cloned. The three-dimensional structure of human 17β-HSD1 is the first example of any human steroid converting enzyme. The human enzyme's structure and biological function have thus been studied extensively in the last two decades. In humans, the enzyme is expressed in placenta, ovary, endometrium and breast. The high activity of estrogen activation provides the basis of 17β-HSD1's implication in estrogen-dependent diseases, such as breast cancer, endometriosis and non-small cell lung carcinomas. Its dual function in estrogen activation and androgen inactivation has been revealed in molecular and breast cancer cell levels, significantly stimulating the proliferation of such cells. The enzyme's overexpression in breast cancer was demonstrated by clinical samples. Inhibition of human 17β-HSD1 led to xenograft tumor shrinkage. Unfortunately, through decades of studies, there is still no drug using the enzyme's inhibitors available. This is due to the difficulty to get rid of the estrogenic activity of its inhibitors, which are mostly estrogen analogues. New non-steroid inhibitors for the enzyme provide new hope for non-estrogenic inhibitors of the enzyme.

Identification and characterization of novel and conserved microRNAs in several tissues of the Chinese rare minnow (Gobiocypris rarus) based on illumina deep sequencing technology

BACKGROUND

MicroRNAs (miRNAs), which comprise a large family of endogenous small non-coding RNA molecules, play important roles in the regulation of gene expression in various biological processes. The Chinese rare minnow (Gobiocypris rarus) is a Chinese native fish species and is used extensively as an experimental fish in China; however, relevant biological data, especially miRNA transcriptome data, have not been well documented. To discover conserved and potential novel miRNAs in Chinese rare minnows, a pool of equal amounts of RNA obtained from 6 different adult rare minnow tissues (brain, eye, gill, liver, muscle and heart) was sequenced using illumina deep sequencing technology.

RESULTS

In the present study, 26,930,553 raw reads, representing 2,118,439 unique high-quality reads, were obtained from the pooled small RNA library. Using bioinformatics analysis, 352 conserved and 112 novel Chinese rare minnow miRNAs were first discovered and characterized in this study. Moreover, we found extensive sequence variations (isomiRs) in rare minnow miRNAs, including internal miRNA isomiRs and terminal isomiRs at both the 5' and 3' ends and nucleotide variants. Six conserved and 4 novel miRNAs were selected and validated in 6 different adult rare minnow tissues using quantitative real-time PCR (qPCR). The results showed that miR-30a, miR-30b, and Novel-37 are ubiquitously expressed in a variety of tissues. miR-16a, miR-9, miR-125b, miR-34a, and Novel-69 were predominantly expressed in the brain. Novel-115 and Novel-7 were highly expressed in gills, but were relatively weakly expressed in other tissues. These results provided the expression patterns of miRNA genes in Chinese rare minnow. Finally, based on bioinformatics predictions, we mainly found that Novel-94 and Novel-1b-5p were simultaneously targeted to the 3'UTR of Dmrt1, which controls sex determination and/or sexual differentiation in a variety of metazoans at different sites. Novel-29b targeted the 3'UTR of Foxl2, which is involved in the maintenance of ovarian function and the transcriptional regulation of gonadal differentiation-related genes. Novel-62 and Novel-53 targeted the 3'UTR of ERbeta1 and ERbeta2 (which regulate the transcription of target genes), respectively.

CONCLUSIONS

Rare minnow is a widely used model for assessing the risk of environmental pollution in China. Identifying and characterizing rare minnow miRNA genes is necessary to discover the biological function of miRNAs and to screen for new molecule biomarkers to assess the risk of environmental pollution in the future.

Effects of the lifestyle habits in breast cancer transcriptional regulation

Through research carried out in the last 25 years about the breast cancer etiology, it has been possible to estimate that less than 10 % of patients who are diagnosed with the condition are carriers of some germline or somatic mutation. The clinical reports of breast cancer patients with healthy twins and the development of disease in women without high penetrance mutations detected, warn the participation more factors in the transformation process. The high incidence of mammary adenocarcinoma in the modern woman and the urgent need for new methods of prevention and early detection have demanded more information about the role that environment and lifestyle have on the transformation of mammary gland epithelial cells. Obesity, alcoholism and smoking are factors that have shown a close correlation with the risk of developing breast cancer. And although these conditions affect different cell regulation levels, the study of its effects in the mechanisms of transcriptional and epigenetic regulation is considered critical for a better understanding of the loss of identity of epithelial cells during carcinogenesis of this tissue. The main objective of this review was to establish the importance of changes occurring to transcriptional level in the mammary gland as a consequence of acute or chronic exposure to harmful products such as obesity-causing foods, ethanol and cigarette smoke components. At analyze the main studies related to topic, it has concluded that the understanding of effects caused by the lifestyle factors in performance of the transcriptional mechanisms that determine gene expression of the mammary gland epithelial cells, may help explain the development of this disease in women without genetic propensity and different phenotypic manifestations of this cancer type.

Active FOXO1 Is a Key Determinant of Isoform-Specific Progesterone Receptor Transactivation and Senescence Programming

Progesterone promotes differentiation coupled to proliferation and prosurvival in the breast, but inhibits estrogen-driven growth in the reproductive tract and ovaries. Herein, it is demonstrated, using progesterone receptor (PR) isoform-specific ovarian cancer model systems, that PR-A and PR-B promote distinct gene expression profiles that differ from PR-driven genes in breast cancer cells. In ovarian cancer models, PR-A primarily regulates genes independently of progestin, while PR-B is the dominant ligand-dependent isoform. Notably, FOXO1 and the PR/FOXO1 target gene p21 (CDKN1A) are repressed by PR-A, but induced by PR-B. In the presence of progestin, PR-B, but not PR-A, robustly induced cellular senescence via FOXO1-dependent induction of p21 and p15 (CDKN2B). Chromatin immunoprecipitation (ChIP) assays performed on PR isoform-specific cells demonstrated that while each isoform is recruited to the same PRE-containing region of the p21 promoter in response to progestin, only PR-B elicits active chromatin marks. Overexpression of constitutively active FOXO1 in PR-A-expressing cells conferred robust ligand-dependent upregulation of the PR-B target genes GZMA, IGFBP1, and p21, and induced cellular senescence. In the presence of endogenous active FOXO1, PR-A was phosphorylated on Ser294 and transactivated PR-B at PR-B target genes; these events were blocked by the FOXO1 inhibitor (AS1842856). PR isoform-specific regulation of the FOXO1/p21 axis recapitulated in human primary ovarian tumor explants treated with progestin; loss of progestin sensitivity correlated with high AKT activity.

IMPLICATIONS

This study indicates FOXO1 as a critical component for progesterone signaling to promote cellular senescence and reveals a novel mechanism for transcription factor control of hormone sensitivity.

Heregulin Co-opts PR Transcriptional Action Via Stat3 Role As a Coregulator to Drive Cancer Growth

Accumulated findings have demonstrated the presence of bidirectional interactions between progesterone receptor (PR) and the ErbB family of receptor tyrosine kinases signaling pathways in breast cancer. We previously revealed signal transducer and activator of transcription 3 (Stat3) as a nodal convergence point between said signaling pathways proving that Stat3 is activated by one of the ErbBs' ligands, heregulin (HRG)β1 via ErbB2 and through the co-option of PR as a signaling molecule. Here, we found that HRGβ1 induced Stat3 recruitment to the promoters of the progestin-regulated cell cycle modulators Bcl-XL and p21(CIP1) and also stimulated Stat3 binding to the mouse mammary tumor virus promoter, which carries consensus progesterone response elements. Interestingly, HRGβ1-activated Stat3 displayed differential functions on PR activity depending on the promoter bound. Indeed, Stat3 was required for PR binding in bcl-X, p21(CIP1), and c-myc promoters while exerting a PR coactivator function on the mouse mammary tumor virus promoter. Stat3 also proved to be necessary for HRGβ1-induced in vivo tumor growth. Our results endow Stat3 a novel function as a coregulator of HRGβ1-activated PR to promote breast cancer growth. These findings underscore the importance of understanding the complex interactions between PR and other regulatory factors, such as Stat3, that contribute to determine the context-dependent transcriptional actions of PR.

YY1 regulates melanoma tumorigenesis through a miR-9 ~ RYBP axis

Background

The Yin Yang 1 (YY1) transcription factor has been identified to target a plethora of potential target genes, which are important for cell proliferation and differentiation. Although the role that YY1 plays in different human types of cancer has been reported, its biological and mechanistic significance in melanoma has not been well defined.

Methods

Quantitative RT-PCR analysis was used to determine whether aberrant YY1 and miR-9 expression occurred in melanoma, compared with benign nevi and normal tissue controls. Furthermore, the transcriptional regulation of YY1 on miR-9 expression was assessed by using quantitative ChIP-PCR assay. Subsequently, the effects of YY1 and miR-9 on proliferation, cell cycle, migration and invasion of melanoma cells were detected using CCK-8, flow cytometric analysis, wound healing and transwell invasion assays, respectively. Finally, the post-transcriptional regulation of miR-9 on RYBP was analyzed using luciferase reporter and immunoblot analysis.

Results

Elevated YY1 levels were observed in patients with melanoma, compared with benign nevi and normal tissue controls, and the increased YY1 was associated with melanoma metastasis state and tumor stage. Furthermore, YY1 negatively regulated miR-9 transcription. Silencing of YY1 inhibited proliferation, cell cycle progression, migration and invasion in melanoma cells, while ectopic of miR-9 did the same. Additionally, RYBP was shown to be a direct target of miR-9 through binding to its 3′ UTR, thus forming a YY1 ~ miR-9 ~ RYBP axis.

Conclusions

These results identify a novel YY1 ~ miR-9 ~ RYBP axis involved in melanoma tumorigenesis and reinforce the idea that regulatory circuitries involving miRNAs and TFs are prevalent mechanisms.

Progesterone action in breast, uterine, and ovarian cancers

Progesterone and progesterone receptors (PRs) are essential for the development and cyclical regulation of hormone-responsive tissues including the breast and reproductive tract. Altered functions of PR isoforms contribute to the pathogenesis of tumors that arise in these tissues. In the breast, progesterone acts in concert with estrogen to promote proliferative and pro-survival gene programs. In sharp contrast, progesterone inhibits estrogen-driven growth in the uterus and protects the ovary from neoplastic transformation. Progesterone-dependent actions and associated biology in diverse tissues and tumors are mediated by two PR isoforms, PR-A and PR-B. These isoforms are subject to altered transcriptional activity or expression levels, differential crosstalk with growth factor signaling pathways, and distinct post-translational modifications and cofactor-binding partners. Herein, we summarize and discuss the recent literature focused on progesterone and PR isoform-specific actions in breast, uterine, and ovarian cancers. Understanding the complexity of context-dependent PR actions in these tissues is critical to developing new models that will allow us to advance our knowledge base with the goal of revealing novel and efficacious therapeutic regimens for these hormone-responsive diseases.

The role of the histone demethylase KDM4A in cancer

Histone posttranslational modifications are important components of epigenetic regulation. One extensively studied modification is the methylation of lysine residues. These modifications were thought to be irreversible. However, several proteins with histone lysine demethylase functions have been discovered and characterized. Among these proteins, KDM4A is the first histone lysine demethylase shown to demethylate trimethylated residues. This enzyme plays an important role in gene expression, cellular differentiation, and animal development. Recently, it has also been shown to be involved in cancer. In this review, we focus on describing the structure, mechanisms, and function of KDM4A. We primarily discuss the role of KDM4A in cancer development and the importance of KDM4A as a potential therapeutic target.

Endocrine Resistance in Breast Cancer

Around 70% of all breast cancers are estrogen receptor alpha positive and hence their development is highly dependent on estradiol. While the invention of endocrine therapies has revolusioned the treatment of the disease, resistance to therapy eventually occurs in a large number of patients. This paper seeks to illustrate and discuss the complexity and heterogeneity of the mechanisms which underlie resistance and the approaches proposed to combat them. It will also focus on the use and development of methods for predicting which patients are likely to develop resistance.

Co-treatment of mouse antral follicles with 17β-estradiol interferes with mono-2-ethylhexyl phthalate (MEHP)-induced atresia and altered apoptosis gene expression

Mono-2-ethyhexyl phthalate (MEHP) is a metabolite of a plasticizer found in many consumer products. MEHP inhibits mouse ovarian follicle growth by reducing 17β-estradiol (E2) production. Yet, whether MEHP causes follicle death (atresia) is unclear. We hypothesized that MEHP causes atresia by altering apoptosis gene expression, and that E2 co-treatment blocks these effects. Follicles were exposed to MEHP (0.36-36μM)±E2 for 48-96h to determine the effect of MEHP±E2 on atresia and gene expression. MEHP increased atresia, but this effect was blocked by co-treatment with E2. MEHP increased the expression of the pro-apoptotic gene Aifm1, but decreased that of the pro-apoptotic gene Bok and the anti-apoptotic gene Bcl2l10. E2 interfered with MEHP-induced changes in Aifm1 and Bcl2l10. Our findings suggest that decreased E2 levels are required for MEHP-induced follicle atresia and that Aifm1, Bok, and Bcl2l10 are involved in this process.

CDC2 mediates progestin initiated endometrial stromal cell proliferation: a PR signaling to gene expression independently of its binding to chromatin

Although non-genomic steroid receptor pathways have been studied over the past decade, little is known about the direct gene expression changes that take place as a consequence of their activation. Progesterone controls proliferation of rat endometrial stromal cells during the peri-implantation phase of pregnancy. We showed that picomolar concentration of progestin R5020 mimics this control in UIII endometrial stromal cells via ERK1-2 and AKT activation mediated by interaction of Progesterone Receptor (PR) with Estrogen Receptor beta (ERb) and without transcriptional activity of endogenous PR and ER. Here we identify early downstream targets of cytoplasmic PR signaling and their possible role in endometrial stromal cell proliferation. Microarray analysis of global gene expression changes in UIII cells treated for 45 min with progestin identified 97 up- and 341 down-regulated genes. The most over-represented molecular functions were transcription factors and regulatory factors associated with cell proliferation and cell cycle, a large fraction of which were repressors down-regulated by hormone. Further analysis verified that progestins regulate Ccnd1, JunD, Usf1, Gfi1, Cyr61, and Cdkn1b through PR-mediated activation of ligand-free ER, ERK1-2 or AKT, in the absence of genomic PR binding. ChIP experiments show that progestin promoted the interaction of USF1 with the proximal promoter of the Cdc2 gene. Usf1 knockdown abolished Cdc2 progestin-dependent transcriptional regulation and cell proliferation, which also blocked Cdc2 knockdown. We conclude that progestin-induced proliferation of endometrial stromal cells is mediated by ERK1-2 and AKT dependent early regulation of USF1, which directly induces Cdc2. To our knowledge, this is the first description of early target genes of progestin-activated classical PR via crosstalk with protein kinases and independently of hormone receptor binding to the genomic targets.

BRCA1 and estrogen/estrogen receptor in breast cancer: where they interact?

BRCA1 mainly acts as a tumor suppressor and BRCA1 mutation correlates with increased cancer risk. Although it is well recognized that BRCA1 related tumorigenesis is mainly caused by the increased DNA damage and decreased genome stability, it is not clear that why BRCA1 related patients have higher risk for cancer development mainly in estrogen responsive tissues such as breast and ovary. Recent studies suggested that BRCA1 and E-ER (estrogen and estrogen receptor) signaling synergistically regulate the mammary epithelial cell proliferation and differentiation. In this current presentation, we reviewed the correlation between mammary gland epithelial cell transformation and the status of BRCA1 and ER. Then the mechanisms of BRCA1 and E-ER interaction at both gene transcription level and protein-protein interaction level are discussed. Furthermore, the tumorigenic mechanisms are discussed by focusing on the synergistic effect of BRCA1 and E-ER on cell metabolism, ROS management, and antioxidant activity in mammary gland epithelial cells. Also, the possibility of cell de-differentiation promoted by coordinated effect between BRCA1 mutation and E-ER signal is explored. Together, the currently available evidences suggest that BRCA1 mutation and E-ER signal together, contribute to breast tumorigenesis by providing the metabolic support for cancer cell growth and even may directly be involved in promoting the de-differentiation of cancer-prone epithelial cells.

Resveratrol modulates the inflammatory response via an estrogen receptor-signal integration network

Resveratrol has beneficial effects on aging, inflammation and metabolism, which are thought to result from activation of the lysine deacetylase, sirtuin 1 (SIRT1), the cAMP pathway, or AMP-activated protein kinase. In this study, we report that resveratrol acts as a pathway-selective estrogen receptor-α (ERα) ligand to modulate the inflammatory response but not cell proliferation. A crystal structure of the ERα ligand-binding domain (LBD) as a complex with resveratrol revealed a unique perturbation of the coactivator-binding surface, consistent with an altered coregulator recruitment profile. Gene expression analyses revealed significant overlap of TNFα genes modulated by resveratrol and estradiol. Furthermore, the ability of resveratrol to suppress interleukin-6 transcription was shown to require ERα and several ERα coregulators, suggesting that ERα functions as a primary conduit for resveratrol activity.DOI: http://dx.doi.org/10.7554/eLife.02057.001.

Estrogen receptor α-coupled Bmi1 regulation pathway in breast cancer and its clinical implications

Background

Bmi1 has been identified as an important regulator in breast cancer, but its relationship with other signaling molecules such as ERα and HER2 is undetermined.

Methods

The expression of Bmi1 and its correlation with ERα, PR, Ki-67, HER2, p16^INK4a, cyclin D1 and pRB was evaluated by immunohistochemistry in a collection of 92 cases of breast cancer and statistically analyzed. Stimulation of Bmi1 expression by ERα or 17β-estradiol (E2) was analyzed in cell lines including MCF-7, MDA-MB-231, ERα-restored MDA-MB-231 and ERα-knockdown MCF-7 cells. Luciferase reporter and chromatin immunoprecipitation assays were also performed.

Results

Immunostaining revealed strong correlation of Bmi1 and ERα expression status in breast cancer. Expression of Bmi1 was stimulated by 17β-estradiol in ERα-positive MCF-7 cells but not in ERα-negative MDA-MB-231 cells, while the expression of Bmi1 did not alter expression of ERα. As expected, stimulation of Bmi1 expression could also be achieved in ERα-restored MDA-MB-231 cells, and at the same time depletion of ERα decreased expression of Bmi1. The proximal promoter region of Bmi1 was transcriptionally activated with co-transfection of ERα in luciferase assays, and the interaction of the Bmi1 promoter with ERα was confirmed by chromatin immunoprecipitation. Moreover, in breast cancer tissues activation of the ERα-coupled Bmi1 pathway generally correlated with high levels of cyclin D1, while loss of its activity resulted in aberrant expression of p16^INK4a and a high Ki-67 index, which implied a more aggressive phenotype of breast cancer.

Conclusions

Expression of Bmi1 is influenced by ERα, and the activity of the ERα-coupled Bmi1 signature impacts p16^INK4a and cyclin D1 status and thus correlates with the tumor molecular subtype and biologic behavior. This demonstrates the important role which is played by ERα-coupled Bmi1 in human breast cancer.