TNF-alpha enhances estrogen-induced cell proliferation of estrogen-dependent breast tumor cells through a complex containing nuclear factor-kappa B

Single-Cell Transcription Mapping of Murine and Human Mammary Organoids Responses to Female Hormones

During female adolescence and pregnancy, rising levels of hormones result in a cyclic source of signals that control the development of mammary tissue. While such alterations are well understood from a whole-gland perspective, the alterations that such hormones bring to organoid cultures derived from mammary glands have yet to be fully mapped. This is of special importance given that organoids are considered suitable systems to understand cross species breast development. Here we utilized single-cell transcriptional profiling to delineate responses of murine and human normal breast organoid systems to female hormones across evolutionary distinct species. Collectively, our study represents a molecular atlas of epithelial dynamics in response to estrogen and pregnancy hormones.

Single-cell transcription mapping of murine and human mammary organoids responses to female hormones

During female adolescence and pregnancy, rising levels of hormones result in a cyclic source of signals that control the development of mammary tissue. While such alterations are well understood from a whole-gland perspective, the alterations that such hormones bring to organoid cultures derived from mammary glands have yet to be fully mapped. This is of special importance given that organoids are considered suitable systems to understand cross species breast development. Here we utilized single-cell transcriptional profiling to delineate responses of murine and human normal breast organoid systems to female hormones across evolutionary distinct species. Collectively, our study represents a molecular atlas of epithelial dynamics in response to estrogen and pregnancy hormones.

Inhibition of RNA Polymerase III Augments the Anti-Cancer Properties of TNFα

Tumour necrosis factor alpha (TNFα) is a multifunctional cytokine that plays a pivotal role in apoptosis, cell survival, as well as in inflammation and immunity. Although named for its antitumor properties, TNFα also has tumour-promoting properties. TNFα is often present in large quantities in tumours, and cancer cells frequently acquire resistance to this cytokine. Consequently, TNFα may increase the proliferation and metastatic potential of cancer cells. Furthermore, the TNFα-driven increase in metastasis is a result of the ability of this cytokine to induce the epithelial-to-mesenchymal transition (EMT). Overcoming the resistance of cancer cells to TNFα may have a potential therapeutic benefit. NF-κB is a crucial transcription factor mediating inflammatory signals and has a wide-ranging role in tumour progression. NF-κB is strongly activated in response to TNFα and contributes to cell survival and proliferation. The pro-inflammatory and pro-survival function of NF-κB can be disrupted by blocking macromolecule synthesis (transcription, translation). Consistently, inhibition of transcription or translation strongly sensitises cells to TNFα-induced cell death. RNA polymerase III (Pol III) synthesises several essential components of the protein biosynthetic machinery, such as tRNA, 5S rRNA, and 7SL RNA. No studies, however, directly explored the possibility that specific inhibition of Pol III activity sensitises cancer cells to TNFα. Here we show that in colorectal cancer cells, Pol III inhibition augments the cytotoxic and cytostatic effects of TNFα. Pol III inhibition enhances TNFα-induced apoptosis and also blocks TNFα-induced EMT. Concomitantly, we observe alterations in the levels of proteins related to proliferation, migration, and EMT. Finally, our data show that Pol III inhibition is associated with lower NF-κB activation upon TNFα treatment, thus potentially suggesting the mechanism of Pol III inhibition-driven sensitisation of cancer cells to this cytokine.

Crosstalk of Inflammatory Cytokines within the Breast Tumor Microenvironment

Several immune and immunocompetent cells, including dendritic cells, macrophages, adipocytes, natural killer cells, T cells, and B cells, are significantly correlated with the complex discipline of oncology. Cytotoxic innate and adaptive immune cells can block tumor proliferation, and others can prevent the immune system from rejecting malignant cells and provide a favorable environment for tumor progression. These cells communicate with the microenvironment through cytokines, a chemical messenger, in an endocrine, paracrine, or autocrine manner. These cytokines play an important role in health and disease, particularly in host immune responses to infection and inflammation. They include chemokines, interleukins (ILs), adipokines, interferons, colony-stimulating factors (CSFs), and tumor necrosis factor (TNF), which are produced by a wide range of cells, including immune cells, such as macrophages, B-cells, T-cells, and mast cells, as well as endothelial cells, fibroblasts, a variety of stromal cells, and some cancer cells. Cytokines play a crucial role in cancer and cancer-related inflammation, with direct and indirect effects on tumor antagonistic or tumor promoting functions. They have been extensively researched as immunostimulatory mediators to promote the generation, migration and recruitment of immune cells that contribute to an effective antitumor immune response or pro-tumor microenvironment. Thus, in many cancers such as breast cancer, cytokines including leptin, IL-1B, IL-6, IL-8, IL-23, IL-17, and IL-10 stimulate while others including IL-2, IL-12, and IFN-γ, inhibit cancer proliferation and/or invasion and enhance the body's anti-tumor defense. Indeed, the multifactorial functions of cytokines in tumorigenesis will advance our understanding of cytokine crosstalk pathways in the tumor microenvironment, such as JAK/STAT, PI3K, AKT, Rac, MAPK, NF-κB, JunB, cFos, and mTOR, which are involved in angiogenesis, cancer proliferation and metastasis. Accordingly, targeting and blocking tumor-promoting cytokines or activating and amplifying tumor-inhibiting cytokines are considered cancer-directed therapies. Here, we focus on the role of the inflammatory cytokine system in pro- and anti-tumor immune responses, discuss cytokine pathways involved in immune responses to cancer and some anti-cancer therapeutic applications.

A Novel Inflammatory Response-Related Gene Signature Predicts Immune Status and Prognosis of Breast Cancer

PURPOSE

Breast cancer is the most common type of cancer and the leading cause of cancer-related death in women worldwide. In this study, we aimed to construct an inflammatory response-related gene model for predicting the immune status and prognosis of breast cancer patients.

METHODS

We obtained the inflammatory response-related genes from the Molecular Signatures Database. Furthermore, we used univariate Cox regression analysis, the least absolute shrinkage and selection operator (LASSO) regression analysis, and multivariate Cox regression to construct an inflammatory response-related gene signature (IRGS) model based on dataset obtained from The Cancer Genome Atlas (TCGA). Patients were consequently categorized into high-risk and low-risk groups. Kaplan-Meier analysis was used to compare the overall survival (OS) of high-risk and low-risk groups. Following that, we validated the model using a dataset (GSE96058) acquired from Gene Expression Omnibus (GEO) database. Univariate and multivariate Cox analyses were used to determine the independent prognostic value of the IRGS in the TCGA and GSE96058 cohorts. A nomogram was constructed to predict the OS in the TCGA cohort. Further, we used Gene Set Enrichment Analysis (GSEA), CIBERSORT, and single-sample Gene Set Enrichment Analysis (ssGSEA) to evaluate the associations of IRGS with immune-associated pathways and immune infiltration. Finally, the relationship between the expression of the signature genes and drug sensitivity was conducted using Pearson correlation analysis.

RESULTS

We established an IRGS to stratify breast cancer patients into the low-risk and high-risk groups. In both the training and validation sets, patients in the high-risk group had significantly shorter OS than those in the low-risk group. The risk score was significantly correlated with the clinical characteristics and could be used as a tool to predict the prognosis of breast cancer. Moreover, we found that the IRGS risk score was an independent predictor of OS in breast cancer patients, and a nomogram model based on IRGS risk score and other clinical factors could effectively predict the prognosis of breast cancer patients. Furthermore, the IRGS risk score was correlated with immune characteristics and was inversely associated with the abundance of immune cell infiltration. Patients with a low IRGS risk score had higher expression levels of immune checkpoint genes, suggesting that IRGS can be used as a potential indicator for immunotherapy. Finally, we found that the expression levels of prognostic genes were significantly correlated with tumor cell sensitivity to chemotherapeutic drugs.

CONCLUSION

Overall, these findings suggest that the IRGS can be used to predict the prognosis and immune status of breast cancer patients and provide new therapeutic targets for the treatment of these patients.

Characterization of transcriptome diversity and in vitro behavior of primary human high-risk breast cells

Biology and transcriptomes of non-cancerous human mammary epithelial cells at risk for breast cancer development were explored following primary isolation utilizing conditional reprogramming cell technology from mastectomy tissue ipsilateral to invasive breast cancer. Cultures demonstrated consistent categorizable behaviors. Relative viability and mammosphere formation differed between samples but were stable across three different mammary-specific media. E2F cell cycle target genes expression levels were positively correlated with viability and advancing age was inversely associated. Estrogen growth response was associated with Tissue necrosis factor signaling and Interferon alpha response gene enrichment. Neoadjuvant chemotherapy exposure significantly altered transcriptomes, shifting them towards expression of genes linked to mammary stem cell formation. Breast cancer prognostic signature sets include genes that in normal development are limited to specific stages of pregnancy or the menstrual cycle. Sample transcriptomes were queried for stage specific gene expression patterns. All cancer samples and a portion of high-risk samples showed overlapping stages reflective of abnormal gene expression patterns, while other high-risk samples exhibited more stage specific patterns. In conclusion, at-risk cells preserve behavioral and transcriptome diversity that could reflect different risk profiles. It is possible that prognostic platforms analogous to those used for breast cancer could be developed for high-risk mammary cells.

Cancer and Covid-19: Collectively catastrophic

The Covid-19 pandemic has spread rapidly across the globe, resulting in more than 3 million deaths worldwide. The symptoms of Covid-19 are usually mild and non-specific, however in some cases patients may develop acute respiratory distress syndrome (ARDS) and systemic inflammation. Individuals with inflammatory or immunocompromising illnesses, such as cancer, are more susceptible to develop ARDS and have higher rates of mortality. This is mediated through an initial hyperstimulated immune response which results in elevated levels of pro-inflammatory cytokines and a subsequent cytokine storm. This potentiates positive feedback loops which are unable to be balanced by anti-inflammatory mediators. Therefore, elevated levels of IL-1β, as a result of NLRP3 inflammasome activation, as well as IL-6 and TNF-α amongst many others, contribute to the progression of various cancer types. Furthermore, Covid-19 progression is associated with the depletion of CD8⁺ and CD4⁺ T cells, B cell and natural killer cell numbers. Collectively, a Covid-19-dependent pro-inflammatory profile and immune suppression promotes the optimal microenvironment for tumourigenesis, initiation and immune evasion of malignant cells, tumour progression and metastasis as well as cancer recurrence. There are, however, therapeutic windows of opportunity that may combat both Covid-19 and cancer to improve patient outcomes.

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.

Local Biomarkers Involved in the Interplay between Obesity and Breast Cancer

Simple Summary

Breast cancer is the second most common cancer in women worldwide. The risk of developing breast cancer depends on various mechanisms, such as age, heredity, reproductive factors, physical inactivity, and obesity. Obesity increases the risk of breast cancer and worsens outcomes for breast cancer patients. The rate of obesity is increasing worldwide, stressing the need for awareness of the association between obesity and breast cancer. In this review, we outline the biomarkers—including cellular and soluble factors—in the breast, associated with obesity, that affect the risk of breast cancer and breast cancer prognosis. Through these biomarkers, we aim to better identify patients with obesity with a higher risk of breast cancer and an inferior prognosis.

Abstract

Obesity is associated with an increased risk of breast cancer, which is the most common cancer in women worldwide (excluding non-melanoma skin cancer). Furthermore, breast cancer patients with obesity have an impaired prognosis. Adipose tissue is abundant in the breast. Therefore, breast cancer develops in an adipose-rich environment. During obesity, changes in the local environment in the breast occur which are associated with breast cancer. A shift towards a pro-inflammatory state is seen, resulting in altered levels of cytokines and immune cells. Levels of adipokines, such as leptin, adiponectin, and resistin, are changed. Aromatase activity rises, resulting in higher levels of potent estrogen in the breast. Lastly, remodeling of the extracellular matrix takes place. In this review, we address the current knowledge on the changes in the breast adipose tissue in obesity associated with breast cancer initiation and progression. We aim to identify obesity-associated biomarkers in the breast involved in the interplay between obesity and breast cancer. Hereby, we can improve identification of women with obesity with an increased risk of breast cancer and an impaired prognosis. Studies investigating mammary adipocytes and breast adipose tissue in women with obesity versus women without obesity are, however, sparse and further research is needed.

Molecular insights into the interplay between adiposity, breast cancer and bone metastasis

Cancer is a complex disease, with various pre-existing health ailments enhancing its pathology. In cancer, the extracellular environment contains various intrinsic physiological factors whose levels are altered with aging and pre-existing conditions. In obesity, the tumor microenvironment and metastases are enriched with factors that are both derived locally, and from other physiological compartments. Similarly, in obesity, the cancer cell environment both at the site of origin and at the secondary site i.e., metastatic niche, contains significantly more phenotypically-altered adipocytes than that of un-obese cancer patients. Indeed, obesity has been linked with cancer progression, metastasis, and therapy resistance. Adipocytes not only interact with tumor cells, but also with adjacent stromal cells at primary and metastatic sites. This review emphasizes the importance of bidirectional interactions between adipocytes and breast tumor cells in breast cancer progression and its bone metastases. This paper not only chronicles the role of various adipocyte-derived factors in tumor growth, but also describes the significance of adipocyte-derived bone metastatic factors in the development of bone metastasis of breast cancer. It provides a molecular view of the interplay between the adipocytes and tumor cells involved in breast cancer bone metastasis. However, more research is needed to determine if targeting cancer-associated adipocytes holds promise as a potential therapeutic approach for breast cancer bone metastasis treatment. Interplay between adipocytes and breast cancer cells at primary cancer site and metastatic bone microenvironment. AMSC Adipose-derived mesenchymal stem cell, CAA Cancer associated adipocytes, CAF Cancer associated fibroblast, BMSC Bone marrow derived mesenchymal stem cell, BMA Bone marrow adipocyte.

Toll-like receptor (TLR) gene expression and immunostimulatory effect of CpG oligonucleotides in hormone receptor positive cell line T47D and triple negative breast cancer cell line MDA-MB-468

BACKGROUND

We investigated the expression of TLR genes and the effects of CpG ODN in Estrogen Receptor positive, Progesterone Receptor positive breast cancer cell line (T47D) and a triple-negative breast cancer cell line (MDA-MB-468) followed by studying the immunostimulatory activity of CpG oligonucleotides in breast cancer cell lines T47D and MDA-MB-468.

MATERIALS AND METHODS

We evaluated the expression pattern of TLR genes (TLR1 to TLR9) in T47D and MDA-MB-468 cells using Real-time qPCR analysis. The intracellular TLR9 protein expression was studied by flow cytometry. The effect of CpG ODN on cell viability was tested using MTT assay. The relative expression of pro-inflammatory (IL6 and TNFα) and anti- inflammatory/immunosuppressive cytokines genes (IL10 and TGF beta1) were examined by Real-time qPCR.

RESULTS

We found that MDA-MB-468 cells expressed TLR2, TLR3, TLR6, TLR8, and TLR9 genes and T47D cells expressed TLR3, TRL5, TLR8, and TLR9 genes. Stimulation of TLR9 in vitro with CpG significantly reduced the cell viability of T47D and MDA-MB-468 cells. IL6 cytokine gene expression was significantly reduced in both CpG treated T47D cells and MDA-MB-468 cells. TNFα gene expression was significantly reduced after treatment with CpG in MDA-MB-468 cells but not in T47D cells. IL10 and TGFβ1 expression were downregulated in CpG treated T47D cells. Whereas, IL10 and TGFβ1 were elevated in CpG treated MDA-MB-468 cells.

CONCLUSION

Our in vitro finding gives preliminary evidence that triggering TLR9 using CpG ODN decreases the cell proliferation and alters the pro-inflammatory cytokines in favor of inhibition of hormone receptor positive breast cancer cells T47D and triple negative breast cancer cells MDA-MB-468.

Polymorphisms in the Tumor Necrosis Factor Genes Are Associated with Breast Cancer in the Moroccan Population

Background: The multifunctional cytokines of the tumor necrosis factor (TNF) family have been found to be involved in the promotion of inflammatory responses, and to play critical roles in the pathogenesis of inflammatory, autoimmune, and malignant diseases. The aim of the present study was to assess the associations among the TNFα -238 G > A (rs361525), TNFα -308 G > A (rs1800629), and TNFβ +252 A>G (rs909253) polymorphisms, and the breast cancer (BC) susceptibility in the Moroccan population. Materials and Methods: We conducted a case-control study, including 492 participants made up of 264 pathologically confirmed BC subjects, and 228 healthy women as controls. The samples were genotyped by means of polymerase chain reaction-restriction fragment length polymorphism analyses. Results: The TNFα -238 G > A and TNFα -308 G > A polymorphisms were significantly associated with increased risk of BC for the AA genotype, while, the AG genotype of TNFβ +252 A>G may offer a protective effect in this population. Haplotypic analyses showed that the GAA and AAG haplotypes increased the risk significantly for BC. Moreover, a significant association was observed between polymorphisms at the TNFα -238 A>G locus and the clinical profiles of the patients with regard to their estrogen-and progesterone-positive receptor status. Conclusion: These findings indicate that TNF gene polymorphisms are linked with the risk of BC in the Moroccan population. Further studies implementing a larger sample size are needed to support our findings.

Tumor Necrosis Factor α Blockade: An Opportunity to Tackle Breast Cancer

Breast cancer is the most frequently diagnosed cancer and the principal cause of mortality by malignancy in women and represents a main problem for public health worldwide. Tumor necrosis factor α (TNFα) is a pro-inflammatory cytokine whose expression is increased in a variety of cancers. In particular, in breast cancer it correlates with augmented tumor cell proliferation, higher malignancy grade, increased occurrence of metastasis and general poor prognosis for the patient. These characteristics highlight TNFα as an attractive therapeutic target, and consequently, the study of soluble and transmembrane TNFα effects and its receptors in breast cancer is an area of active research. In this review we summarize the recent findings on TNFα participation in luminal, HER2-positive and triple negative breast cancer progression and metastasis. Also, we describe TNFα role in immune response against tumors and in chemotherapy, hormone therapy, HER2-targeted therapy and anti-immune checkpoint therapy resistance in breast cancer. Furthermore, we discuss the use of TNFα blocking strategies as potential therapies and their clinical relevance for breast cancer. These TNFα blocking agents have long been used in the clinical setting to treat inflammatory and autoimmune diseases. TNFα blockade can be achieved by monoclonal antibodies (such as infliximab, adalimumab, etc.), fusion proteins (etanercept) and dominant negative proteins (INB03). Here we address the different effects of each compound and also analyze the use of potential biomarkers in the selection of patients who would benefit from a combination of TNFα blocking agents with HER2-targeted treatments to prevent or overcome therapy resistance in breast cancer.

The dual role of tumor necrosis factor-alpha (TNF-α) in breast cancer: molecular insights and therapeutic approaches

BACKGROUND

Breast cancer is the most prevalent cancer among women worldwide and the fifth cause of death among all cancer patients. Breast cancer development is driven by genetic and epigenetic alterations, with the tumor microenvironment (TME) playing an essential role in disease progression and evolution through mechanisms like inflammation promotion. TNF-α is one of the essential pro-inflammatory cytokines found in the TME of breast cancer patients, being secreted both by stromal cells, mainly by tumor-associated macrophages, and by the cancer cells themselves. In this review, we explore the biological and clinical impact of TNF-α in all stages of breast cancer development. First of all, we explore the correlation between TNF-α expression levels at the tumor site or in plasma/serum of breast cancer patients and their respective clinical status and outcome. Secondly, we emphasize the role of TNF-α signaling in both estrogen-positive and -negative breast cancer cells. Thirdly, we underline TNF-α involvement in epithelial-to-mesenchymal transition (EMT) and metastasis of breast cancer cells, and we point out the contribution of TNF-α to the development of acquired drug resistance.

CONCLUSIONS

Collectively, these data reveal a pro-tumorigenic role of TNF-α during breast cancer progression and metastasis. We systemize the knowledge regarding TNF-α-related therapies in breast cancer, and we explain how TNF-α may act as both a target and a drug in different breast cancer therapeutic approaches. By corroborating the known molecular effects of TNF-α signaling in breast cancer cells with the results from several preclinical and clinical trials, including TNF-α-related clinical observations, we conclude that the potential of TNF-α in breast cancer therapy promises to be of great interest.

Partners in crime: TNFα-based networks promoting cancer progression

Current therapeutic approaches in malignancy are often based on combination therapies, reflecting present understanding of the way different players act together in cancer. The cooperative activity of several elements can potentiate the pro-metastatic functions of the cancer cells and of the tumor microenvironment (TME), together leading to a more aggressive disease phenotype. The design of improved therapeutic modalities requires better identification of networks that act at specific cancer-related settings, and of the molecular mechanisms involved. Such studies will indicate if therapies that co-target several factors or their receptors, simultaneously, could apply. Also, by delineating the intracellular pathways that are activated under such cooperative activities, it will be possible to determine whether to inhibit one specific molecular route that is shared by the different partners, or alternatively, design modalities that jointly target intracellular components acting in concert. This Focused Research Review illuminates the therapeutic relevance of this research field by describing our published findings in breast cancer-related publications, which identified networks that are established by the pro-inflammatory/pro-metastatic cytokine TNFα. It describes the additive/synergistic activities of TNFα with other soluble factors residing at the TME (e.g., IL-1β, TGFβ1, estrogen, EGF), with intracellular components such as the Ras oncogene, and with the tumor-stroma contexture through the activation of molecular cascades (Notch). The roles of the p65 (NF-κB) pathway-acting alone or in intricate relationships with other intracellular mechanisms-are described, the "TNFα-based network" is discussed as a general paradigm in malignancy and its clinical implications in cancer therapy are addressed.

Pathological and molecular characteristics of inflammatory breast cancer

Inflammatory breast cancer (IBC) is a rare and aggressive form of breast cancer characterized by the presence of many dermal tumor emboli in the papillary and reticular dermis of the skin overlying the breast. IBC patients, compared to other breast cancer patients, have more frequently metastatic axillary lymph nodes. IBC is often high grade, negative for hormone receptors and presents with amplification of the HER2 gene. Invasive IBC is frequently of ductal phenotype, even if a specific histological distinction for these lesions has not been described. The pathogenesis and evolution of IBC are strongly dependent upon tumor microenvironment, characterized by several macrophages/monocytes and lymphocytes. The tumor and microenvironment cells are well molecularly characterized, showing the main contributor of inflammatory pathways in tumor biology of IBC. In addition, several molecular alterations are described in this tumor, such as mutations of ERBB2, KRAS, BRAF, EGFR, PIK3CA, PTEN, AKT1, and AKT3 genes that could suggest a therapeutic stratification of IBC patients with the combination of different biological target therapies.

The Effects of Adipocytes on the Regulation of Breast Cancer in the Tumor Microenvironment: An Update

Obesity is a global pandemic and it is well evident that obesity is associated with the development of many disorders including many cancer types. Breast cancer is one of that associated with a high mortality rate. Adipocytes, a major cellular component in adipose tissue, are dysfunctional during obesity and also known to promote breast cancer development both in vitro and in vivo. Dysfunctional adipocytes can release metabolic substrates, adipokines, and cytokines, which promote proliferation, progression, invasion, and migration of breast cancer cells. The secretion of adipocytes can alter gene expression profile, induce inflammation and hypoxia, as well as inhibit apoptosis. It is known that excessive free fatty acids, cholesterol, triglycerides, hormones, leptin, interleukins, and chemokines upregulate breast cancer development. Interestingly, adiponectin is the only adipokine that has anti-tumor properties. Moreover, adipocytes are also related to chemotherapeutic resistance, resulting in the poorer outcome of treatment and advanced stages in breast cancer. Evaluation of the adipocyte secretion levels in the circulation can be useful for prognosis and evaluation of the effectiveness of cancer therapy in the patients. Therefore, understanding about functions of adipocytes as well as obesity in breast cancer may reveal novel targets that support the development of new anti-tumor therapy. In this systemic review, we summarize and update the effects of secreted factors by adipocytes on the regulation of breast cancer in the tumor microenvironment.

Mindfulness based stress reduction provides psychological benefit and restores immune function of women newly diagnosed with breast cancer: A randomized trial with active control

BACKGROUND

Women newly diagnosed with breast cancer experience psychological distress, accompanied by reduced Natural Killer Cell Activity (NKCA) and altered levels of cytokines, which may compromise cancer control. Few studies have evaluated psycho-immune outcomes of mindfulness-based stress reduction (MBSR) for women newly diagnosed with breast cancer in comparison to an active control condition.

OBJECTIVE

The purpose of this study was to determine whether MBSR benefits psychological, behavioral, and immunological function in women recently diagnosed with breast cancer.

DESIGN

After confirmation of breast cancer staging, women diagnosed with early-stage breast cancer (n = 192) were randomized to an 8-week MBSR program or an 8-week active control condition (ACC). The ACC consisted of a series of cancer recovery and health education classes. Both MBSR and the ACC were administered in group format.

METHODS

Women completed psychometric instruments and provided blood for NKCA and cytokine levels at pre-, mid-, and completion of program, as well as at 1- and 6-months post-program. One hundred and twenty four women completed all five-assessments (MBSR, n = 63; ACC, n = 61). Hierarchical linear modeling was used to analyze trajectories of outcomes over time and between groups.

RESULTS

Compared to the ACC group, women randomized to MBSR exhibited decreasing trajectories of perceived stress, fatigue, sleep disturbance, and depressive symptoms. Further, compared to women randomized to ACC, MBSR women exhibited trajectories demonstrating significantly more rapid restoration of NKCA, accompanied by lower circulating TNF-alpha levels, lower IL-6 production, and greater IFN-gamma production.

CONCLUSIONS

These results demonstrate early provision of MBSR for women newly diagnosed with breast cancer provides not only psychological benefit, but also optimizes immune function supportive of cancer control.

The inflammatory cytokine TNF contributes with RAC3-induced malignant transformation

RAC3 is a coactivator of steroid receptors and NF-κB. It is usually overexpressed in several tumors, contributes to maintain cancer stem cells and also to induce them when is overexpressed in non-tumoral cells. In this work, we investigated whether the inflammatory cytokine TNF may contribute to the transforming effects of RAC3 overexpression in the non-tumoral HEK293 cell line.

The study model included the HEK293 tumoral transformed cell line constitutively overexpressing RAC3 by stable transfection and control non-tumoral cells transfected with an empty vector. The HeLa and T47D tumoral cells that naturally overexpress RAC3 were used as positive control.

We found that TNF potentiated RAC3-induced mesenchymal transition, involving an increased E-Cadherin downregulation, Vimentin and SNAIL upregulation and enhanced migratory behavior. Moreover, concerning the molecular mechanisms by which TNF potentiates the RAC3 transforming action, they involve the IKK activation, which in addition induced the β-Catenin transactivation.

Our results demonstrate that although RAC3 overexpression could be a signal strong enough to induce cancer stem cells, the inflammatory microenvironment may be playing a key role contributing to the migratory and invasive phenotype required for metastasis and cancer persistence.

Role of RAC3 coactivator in the adipocyte differentiation

RAC3 is a member of the p160 family of steroid receptor coactivators and it is highly expressed in several human cancers, contributing to enhanced cell proliferation and cellular transformation. In this work, we have studied the role of RAC3 in adipogenesis in L-929 cells. Adipogenesis is a highly regulated process, involving cell cycle arrest and changes in the gene expression pattern required for morphological remodelling. We found that RAC3 expression levels are downregulated during adipocyte differentiation induced by specific stimulus. In addition, cells constitutively expressing low levels of RAC3 (shRNA), showed enhanced adipocyte differentiation which was evidenced by the early detection of the adipocyte markers Perilipin, PPARγ and Oil Red O staining. Moreover, RAC3 downregulation favoured cell arrest and autophagy. Early and late autophagy inhibitors blocked adipocyte differentiation in control cells, but partially inhibited shRAC3 differentiation, demonstrating that although autophagy is required for adipogenesis, additional signals could be trigged by RAC3 downregulation. We conclude that RAC3 is a key regulator of adipogenesis, since its downregulation generates the cellular arrest and autophagic responses that are required steps for this process.

Obesity and Cancer: Existing and New Hypotheses for a Causal Connection

Existing explanations of obesity-associated cancer emphasise direct mutagenic effects of dietary components or hormonal imbalance. Some of these hypotheses are reviewed briefly, but recent evidence suggests a major role for chronic inflammation in cancer risk, possibly involving dietary content. These ideas include the inflammation-induced activation of the kynurenine pathway and its role in feeding and metabolism by activation of the aryl hydrocarbon receptor (AHR) and by modulating synaptic transmission in the brain. Evidence for a role of the kynurenine pathway in carcinogenesis then provides a potentially major link between obesity and cancer. A second new hypothesis is based on evidence that serine proteases can deplete cells of the tumour suppressors Deleted in Colorectal Cancer (DCC) and neogenin. These enzymes include mammalian chymotryptic proteases released by pro-inflammatory neutrophils and macrophages. Blood levels of chymotrypsin itself increase in parallel with food intake. The mechanistically similar bacterial enzyme subtilisin is widespread in the environment, animal probiotics, meat processing and cleaning products. Simple public health schemes in these areas, with selective serine protease inhibitors and AHR antagonists and could prevent a range of intestinal and other cancers.

NF-κB at the Crossroads of Normal Mammary Gland Biology and the Pathogenesis and Prevention of BRCA1-Mutated Breast Cancer

Recent studies have shown that progesterone receptor (PR)-expressing cells respond to progesterone in part through the induction of the receptor activator of NF-κB ligand (RANKL), which acts in a paracrine manner to induce expansion of a RANK-expressing luminal progenitor cell population. The RANK⁺ population in human breast tissue from carriers of BRCA1 mutations (BRCA1^mut/+) as well as the luminal progenitor population in Brca1-deficient mouse mammary glands is abnormally amplified. Remarkably, mouse Brca1^+/- and human BRCA1^mut/+ progenitor cells are able to form colonies in vitro in the absence of progesterone, demonstrating a hormone-independent proliferative capacity. Our research has demonstrated that proliferation in BRCA1-deficient cells results in a DNA damage response (DDR) that activates a persistent NF-κB signal, which supplants progesterone/RANKL signaling for an extended time period. Thus, the transcriptional targets normally activated by RANKL that promote a proliferative response in luminal progenitors can contribute to the susceptibility of mammary epithelial cells to BRCA1-mutated breast cancers as a consequence of DDR-induced NF-κB. Together, these latest findings mark substantial progress in uncovering the mechanisms driving high rates of breast tumorigenesis in BRCA1 mutation carriers and ultimately reveal possibilities for nonsurgical prevention strategies. Cancer Prev Res; 11(2); 69-80. ©2017 AACR.

Challenging a Misnomer? The Role of Inflammatory Pathways in Inflammatory Breast Cancer

Inflammatory breast cancer is a rare, yet highly aggressive form of breast cancer, which accounts for less than 5% of all locally advanced presentations. The clinical presentation of inflammatory breast cancer often differs significantly from that of noninflammatory breast cancer; however, immunohistochemistry reveals few, if any, distinguishing features. The more aggressive triple-negative and HER2-positive breast cancer subtypes are overrepresented in inflammatory breast cancer compared with noninflammatory breast cancer, with a poorer prognosis in response to conventional therapies. Despite its name, there remains some controversy regarding the role of inflammation in inflammatory breast cancer. This review summarises the current molecular evidence suggesting that inflammatory signaling pathways are upregulated in this disease, including NF-κB activation and excessive IL-6 production among others, which may provide an avenue for novel therapeutics. The role of the tumor microenvironment, through tumor-associated macrophages, infiltrating lymphocytes, and cancer stem cells is also discussed, suggesting that these tumor extrinsic factors may help account for the differences in behavior between inflammatory breast cancer and noninflammatory breast cancer. While there are various novel treatment strategies already underway in clinical trials, the need for further development of preclinical models of this rare but aggressive disease is paramount.

Humanin inhibits apoptosis in pituitary tumor cells through several signaling pathways including NF-κB activation

Humanin (HN) and Rattin (HNr), its homologous in the rat, are peptides with cytoprotective action in several cell types such as neurons, lymphocytes and testicular germ cells. Previously, we have shown that HNr is expressed in pituitary cells and that HN inhibited the apoptotic effect of TNF-α in both normal and tumor pituitary cells. The aim of the present study was to identify signaling pathways that mediate the antiapoptotic effect of HN in anterior pituitary cells from ovariectomized rats and in GH3 cells, a somatolactotrope cell line. We assessed the role of STAT3, JNK, Akt and MAPKs as well as proteins of the Bcl-2 family, previously implicated in the antiapoptotic effect of HN. We also evaluated the participation of NF-κB in the antiapoptotic action of HN. STAT3 inhibition reversed the inhibitory effect of HN on TNF-α-induced apoptosis in normal and pituitary tumor cells, indicating that STAT3 signaling pathway mediates the antiapoptotic effect of HN on pituitary cells. Inhibition of NF-κB pathway did not affect action of HN on normal anterior pituitary cells but blocked the cytoprotective effect of HN on TNF-α-induced apoptosis of GH3 cells, suggesting that the NF-κB pathway is involved in HN action in tumor pituitary cells. HN also induced NF-κB-p65 nuclear translocation in these cells. In pituitary tumor cells, JNK and MEK inhibitors also impaired HN cytoprotective action. In addition, HN increased Bcl-2 expression and decreased Bax mitochondrial translocation. Since HN expression in GH3 cells is higher than in normal pituitary cells, we may suggest that through multiple pathways HN could be involved in pituitary tumorigenesis.

ClC-3 Chloride Channel Proteins Regulate the Cell Cycle by Up-regulating cyclin D1-CDK4/6 through Suppressing p21/p27 Expression in Nasopharyngeal Carcinoma Cells

It was shown in this study that knockdown of ClC-3 expression by ClC-3 siRNA prevented the activation of hypotonicity-induced chloride currents, and arrested cells at the G0/G1 phase in nasopharyngeal carcinoma CNE-2Z cells. Reconstitution of ClC-3 expression with ClC-3 expression plasmids could rescue the cells from the cell cycle arrest caused by ClC-3 siRNA treatments. Transfection of cells with ClC-3 siRNA decreased the expression of cyclin D1, cyclin dependent kinase 4 and 6, and increased the expression of cyclin dependent kinase inhibitors (CDKIs), p21 and p27. Pretreatments of cells with p21 and p27 siRNAs depleted the inhibitory effects of ClC-3 siRNA on the expression of CDK4 and CDK6, but not on that of cyclin D1, indicating the requirement of p21 and p27 for the inhibitory effects of ClC-3 siRNA on CDK4 and CDK6 expression. ClC-3 siRNA inhibited cells to progress from the G1 phase to the S phase, but pretreatments of cells with p21 and p27 siRNAs abolished the inhibitory effects of ClC-3 siRNA on the cell cycle progress. Our data suggest that ClC-3 may regulate cell cycle transition between G0/G1 and S phases by up-regulation of the expression of CDK4 and CDK6 through suppression of p21 and p27 expression.

Targeting truncated RXRα for cancer therapy

Retinoid X receptor-alpha (RXRα), a unique member of the nuclear receptor superfamily, is a well-established drug target, representing one of the most important targets for pharmacologic interventions and therapeutic applications for cancer. However, how RXRα regulates cancer cell growth and how RXRα modulators suppress tumorigenesis are poorly understood. Altered expression and aberrant function of RXRα are implicated in the development of cancer. Previously, several studies had demonstrated the presence of N-terminally truncated RXRα (tRXRα) proteins resulted from limited proteolysis of RXRα in tumor cells. Recently, we discovered that overexpression of tRXRα can promote tumor growth by interacting with tumor necrosis factor-alpha-induced phosphoinositide 3-kinase and NF-κB signal transduction pathways. We also identified nonsteroidal anti-inflammatory drug Sulindac and analogs as effective inhibitors of tRXRα activities via a unique binding mechanism. This review discusses the emerging roles of tRXRα and modulators in the regulation of cancer cell survival and death as well as inflammation and our recent understanding of tRXRα regulation by targeting the alternate binding sites on its surface.

RAC3 more than a nuclear receptor coactivator: a key inhibitor of senescence that is downregulated in aging

Receptor-associated coactivator 3 (RAC3) is a nuclear receptor coactivator usually overexpressed in tumors that exerts oncogenic functions in the cytoplasm and the nucleus. Although as part of its oncogenic actions it was previously identified as an inhibitor of apoptosis and autophagy, its expression is required in order to preserve the pluripotency and embryonic stem cell self-renewal. In this work we investigated its role in cellular senescence. We found that RAC3 overexpression in the nontumoral HEK293 cells inhibits the premature senescence induced by hydrogen peroxide or rapamycin. The mechanism involves not only the inhibition of autophagy early induced by these stimuli in the pathway to senescence, but also the increase in levels and nuclear localization of both the cell cycle suppressors p53/p21 and the longevity promoters FOXO1A, FOXO3A and SIRT1. Furthermore, we found that RAC3 overexpression is required in order to maintain the telomerase activity. In tumoral HeLa cells its activity was inhibited by depletion of RAC3 inducing replicative senescence. Moreover, we demonstrated that in vivo, levels of RAC3 are downregulated in the liver from aged as compared with young rats, whereas the levels of p21 are increased, correlating with the expected senescent cell contents in aged tissues. A similar downregulation of RAC3 was observed in the premature and replicative senescence of human fetal WI-38 cells and premature senescence of hepatocyte HepG2 cell line. Taken together, all these results demonstrate that RAC3 is an inhibitor of senescence whose downregulation in aged individuals could be probably a tumor suppressor mechanism, avoiding the clonal expansion of risky old cells having damaged DNA.

Regulation of the inflammatory profile of stromal cells in human breast cancer: prominent roles for TNF-α and the NF-κB pathway

Introduction

Breast cancer progression is promoted by stromal cells that populate the tumors, including cancer-associated fibroblasts (CAFs) and mesenchymal stem/stromal cells (MSCs). The activities of CAFs and MSCs in breast cancer are integrated within an intimate inflammatory tumor microenvironment (TME) that includes high levels of tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β). Here, we identified the impact of TNF-α and IL-1β on the inflammatory phenotype of CAFs and MSCs by determining the expression of inflammatory chemokines that are well-characterized as pro-tumorigenic in breast cancer: CCL2 (MCP-1), CXCL8 (IL-8) and CCL5 (RANTES).

Methods

Chemokine expression was determined in breast cancer patient-derived CAFs by ELISA and in patient biopsies by immunohistochemistry. Chemokine levels were determined by ELISA in (1) human bone marrow-derived MSCs stimulated by tumor conditioned media (Tumor CM) of breast tumor cells (MDA-MB-231 and MCF-7) at the end of MSC-to-CAF-conversion process; (2) Tumor CM-derived CAFs, patient CAFs and MSCs stimulated by TNF-α (and IL-1β). The roles of AP-1 and NF-κB in chemokine secretion were analyzed by Western blotting and by siRNAs to c-Jun and p65, respectively. Migration of monocytic cells was determined in modified Boyden chambers.

Results

TNF-α (and IL-1β) induced the release of CCL2, CXCL8 and CCL5 by MSCs and CAFs generated by prolonged stimulation of MSCs with Tumor CM of MDA-MB-231 and MCF-7 cells. Patient-derived CAFs expressed CCL2 and CXCL8, and secreted CCL5 following TNF-α (and IL-1β) stimulation. CCL2 was expressed in CAFs residing in proximity to breast tumor cells in biopsies of patients diagnosed with invasive ductal carcinoma. CCL2 release by TNF-α-stimulated MSCs was mediated by TNF-RI and TNF-RII, through the NF-κB but not via the AP-1 pathway. Exposure of MSCs to TNF-α led to potent CCL2-induced migration of monocytic cells, a process that may yield pro-cancerous myeloid infiltrates in breast tumors.

Conclusions

Our novel results emphasize the important roles of inflammation-stroma interactions in breast cancer, and suggest that NF-κB may be a potential target for inhibition in tumor-adjacent stromal cells, enabling improved tumor control in inflammation-driven malignancies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0080-7) contains supplementary material, which is available to authorized users.

Garcinol, an acetyltransferase inhibitor, suppresses proliferation of breast cancer cell line MCF-7 promoted by 17β-estradiol

The acetyltransferase inhibitor garcinol, a polyisoprenylated benzophenone, is extracted from the rind of the fruit of Garcinia indica, a plant found extensively in tropical regions. Anti-cancer activity has been suggested but there is no report on its action via inhibiting acetylation against cell proliferation, cell cycle progression, and apoptosis-inhibtion induced by estradiol (E2) in human breast cancer MCF-7 cells. The main purposes of this study were to investigate the effects of the acetyltransferase inhibitor garcinol on cell proliferation, cell cycle progression and apoptosis inhibition in human breast cancer MCF-7 cells treated with estrogen, and to explore the significance of changes in acetylation levels in this process. We used a variety of techniques such as CCK-8 analysis of cell proliferation, FCM analysis of cell cycling and apoptosis, immunofluorescence analysis of NF-κB/ p65 localization, and RT-PCR and Western blotting analysis of ac-H3, ac-H4, ac-p65, cyclin D1, Bcl-2 and Bcl- xl. We found that on treatment with garcinol in MCF-7 cells, E2-induced proliferation was inhibited, cell cycle progression was arrested at G0/G1 phase, and the cell apoptosis rate was increased. Expression of ac-H3, ac-H4 and NF-κB/ac-p65 proteins in E2-treated MCF-7 cells was increased, this being inhibited by garcinol but not ac- H4.The nuclear translocation of NF-κB/p65 in E2-treated MCF-7 cells was also inhibited, along with cyclin D1, Bcl-2 and Bcl-xl in mRNA and protein expression levels. These results suggest that the effect of E2 on promoting proliferation and inhibiting apoptosis is linked to hyperacetylation levels of histones and nonhistone NF-κB/ p65 in MCF-7 cells. The acetyltransferase inhibitor garcinol plays an inhibitive role in MCF-7 cell proliferation promoted by E2. Mechanisms are probably associated with decreasing ac-p65 protein expression level in the NF-κB pathway, thus down-regulating the expression of cyclin D1, Bcl-2 and Bcl-xl.

Intratumoural inflammation and endocrine resistance in breast cancer

It is becoming clear that inflammation-associated mechanisms can affect progression of breast cancer and modulate responses to treatment. Estrogen receptor alpha (ERα (ESR1)) is the principal biomarker and therapeutic target for endocrine therapies in breast cancer. Over 70% of patients are ESR1-positive at diagnosis and are candidates for endocrine therapy. However, ESR1-positive tumours can become resistant to endocrine therapy. Multiple mechanisms of endocrine resistance have been proposed, including suppression of ESR1. This review discusses the relationship between intratumoural inflammation and endocrine resistance with a particular focus on inflammation-mediated suppression of ESR1.

Tumor necrosis factor alpha promotes the proliferation of human nucleus pulposus cells via nuclear factor-κB, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinase

Although tumor necrosis factor alpha (TNF-α) is known to play a critical role in intervertebral disc (IVD) degeneration, the effect of TNF-α on nucleus pulposus (NP) cells has not yet been elucidated. The aim of this study was to explore the effect of TNF-α on proliferation of human NP cells. NP cells were treated with different concentrations of TNF-α. Cell proliferation was determined by cell counting kit-8 (CCK-8) analysis and Ki67 immunofluorescence staining, and expression of cyclin B1 was studied by quantitative real-time RT-PCR. Cell cycle was measured by flow cytometry and cell apoptosis was analyzed using an Annexin V-fluorescein isothiocyanate (FITC) & propidium iodide (PI) apoptosis detection kit. To identify the mechanism by which TNF-α induced proliferation of NP cells, selective inhibitors of major signaling pathways were used and Western blotting was carried out. Treatment with TNF-α increased cell viability (as determined by CCK-8 analysis) and expression of cyclin B1 and the number of Ki67-positive and S-phase NP cells, indicating enhancement of proliferation. Consistent with this, NP cell apoptosis was suppressed by TNF-α treatment. Moreover, inhibition of NF-κB, c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK) blocked TNF-α-stimulated proliferation of NP cells. In conclusion, the current findings suggest that the effect of TNF-α on IVD degeneration involves promotion of the proliferation of human NP cells via the NF-κB, JNK, and p38 MAPK pathways.

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.

Inflammatory factors of the tumor microenvironment induce plasticity in nontransformed breast epithelial cells: EMT, invasion, and collapse of normally organized breast textures

Nontransformed breast epithelial cells that are adjacent to tumor cells are constantly exposed to tumor necrosis factor-α (TNFα) and interleukin-1β (IL-1β), two inflammatory cytokines identified as having pro-tumoral causative roles. We show that continuous stimulation of nontransformed breast epithelial cells by TNFα + IL-1β for 2 to 3 weeks induced their spreading and epithelial-to-mesenchymal transition (EMT). The mechanistic bases for this slow induction of EMT by TNFα + IL-1β are: 1) it took 2 to 3 weeks for the cytokines to induce the expression of the EMT activators Zeb1 and Snail; 2) although Twist has amplified the EMT-inducing activities of Zeb1 + Snail, its expression was reduced by TNFα + IL-1β; however, the lack of Twist was compensated by prolonged stimulation with TNFα + IL-1β that has potentiated the EMT-inducing activities of Zeb1 + Snail. Stimulation by TNFα + IL-1β has induced the following dissemination-related properties in the nontransformed cells: 1) up-regulation of functional matrix metalloproteinases; 2) induction of migratory and invasive capabilities; 3) disruption of the normal phenotype of organized three-dimensional acini structures typically formed only by nontransformed breast cells and spreading of nontransformed cells out of such acini. Our findings suggest that TNFα + IL-1β induce dissemination of nontransformed breast epithelial cells and their reseeding at the primary tumor site; if, then, such detached cells are exposed to transforming events, they may form secondary malignant focus and lead to disease recurrence. Thus, our study reveals novel pathways through which the inflammatory microenvironment may contribute to relapsed disease in breast cancer.

Hormonal regulation of the cytokine microenvironment in the mammary gland

The mammary gland is a unique organ that undergoes hormone-driven developmental changes over the course of the ovarian cycle during adult life. Macrophages play a role in regulating cellular turnover in the mammary gland and may affect cancer susceptibility. However, the immune microenvironment that regulates macrophage function has not been described. Hormonal regulation of the cytokine microenvironment across the ovarian cycle was explored using microbead multiplex assay for 15 cytokines in mammary glands from C57Bl/6 mice at different stages of the oestrous cycle, and in ovariectomised mice administered oestradiol and progesterone. The cytokines that were found to fluctuate over the course of the oestrous cycle were colony-stimulating factor (CSF)1, CSF2, interferon gamma (IFNG) and tumour necrosis factor alpha (TNFA), all of which were significantly elevated at oestrus compared with other phases. The concentration of serum progesterone during the oestrus phase negatively correlated with the abundance of cytokines CSF3, IL12p40, IFNG and leukaemia inhibitory factor (LIF). In ovariectomised mice, exogenous oestradiol administration increased mammary gland CSF1, CSF2, IFNG and LIF, compared with ovariectomised control mice. Progesterone administration together with oestradiol resulted in reduced CSF1, CSF3 and IFNG compared with oestradiol administration alone. This study suggests that the cytokine microenvironment in the mammary gland at the oestrus phase of the ovarian cycle is relatively pro-inflammatory compared with other stages of the cycle, and that the oestradiol-induced cytokine microenvironment is significantly attenuated by progesterone. A continuously fluctuating cytokine microenvironment in the mammary gland presumably regulates the phenotypes of resident leukocytes and may affect mammary gland cancer susceptibility.

The levels of RAC3 expression are up regulated by TNF in the inflammatory response

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The inflammatory response increases the expression of RAC3 in vitro and in vivo.

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TNF induces the increase of RAC3 at transcriptional level through NF-κB activation.

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Glucocorticoids also induce the increase of RAC3 expression levels.

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RAC3 appears to be essential for NF-κB- and GR-mediated transcription.

RAC3 is a coactivator of glucocorticoid receptor and nuclear factor-κB (NF-κB) that is usually over-expressed in tumors and which also has important functions in the immune system. We investigated the role of the inflammatory response in the control of RAC3 expression levels in vivo and in vitro. We found that inflammation regulates RAC3 levels. In mice, sub-lethal doses of lipopolysaccharide induce the increase of RAC3 in spleen and the administration of the synthetic anti-inflammatory glucocorticoid dexamethasone has a similar effect. However, the simultaneous treatment with both stimuli is mutually antagonistic. In vitro stimulation of the HEK293 cell line with tumor necrosis factor (TNF), one of the cytokines induced by lipopolysaccharide, also increases the levels of RAC3 mRNA and protein, which correlates with an enhanced transcription dependent on the RAC3 gene promoter. We found that binding of the transcription factor NF-κB to the RAC3 gene promoter could be responsible for these effects. Our results suggest that increase of RAC3 during the inflammatory response could be a molecular mechanism involved in the control of sensitivity to both pro- and anti-inflammatory stimuli in order to maintain the normal healthy course of the immune response.

Contribution of ER and NF-κB to endocrine resistance in inflammatory breast cancer

SUMMARY Inflammatory breast cancer (IBC) is a very aggressive form of breast cancer with a high mortality rate. Most patients have lymph node metastasis at the time of diagnosis and 30% of patients already have metastases in distant organs. IBC is normally treated with multimodality therapy. Endocrine therapy is administered in cases of ER-positive tumors. Nevertheless, IBC has a high HOXB13:Il17RB ratio, predicting a poor response to tamoxifen treatment. These data suggest a possible role for IBC as a model for endocrine resistance. Previous studies have shown that NF-κB, a transcription factor regulating different cellular processes, is more highly activated in IBC than in non-IBC, while ER is often downregulated in this tumor type. This article summarizes the activity of ER and NF-κB in IBC and their possible contribution to endocrine resistance in this breast cancer subtype.

The role of inflammation in inflammatory breast cancer

Inflammatory breast cancer (IBC) is the most aggressive form of breast cancer. Despite extensive study, whether inflammation contributes to the tumorigenicity or aggressiveness of IBC remains largely unknown. In this chapter, we will review the potential role played by inflammation in IBC based on the results of in vitro, in vivo, and patient studies. Current evidence suggests that several major inflammatory signaling pathways are constitutively active in IBC and breast cancer. Among them, the NF-κB, COX-2, and JAK/STAT signaling systems seem to play a major role in the tumorigenesis of IBC. Inflammatory molecules such as interleukin-6, tumor necrosis factor alpha (TNF-α), and gamma interferon have been shown to contribute to malignant transformation in preclinical studies of IBC, while transforming growth factor-β, interleukins 8 and 1β, as well as TNF-α appear to play a role in proliferation, survival, epithelial-mesenchymal transition, invasion, and metastasis. In this chapter, we also describe work thus far involving inhibitors of inflammation in the development of prevention and treatment strategies for IBC.

MEK5/ERK5 signaling suppresses estrogen receptor expression and promotes hormone-independent tumorigenesis

Endocrine resistance and metastatic progression are primary causes of treatment failure in breast cancer. While mitogen activated protein kinases (MAPKs) are known to promote ligand-independent cell growth, the role of the MEK5-ERK5 pathway in the progression of clinical breast carcinoma remains poorly understood. Here, we demonstrated increased ERK5 activation in 30 of 39 (76.9%) clinical tumor samples, as well as across breast cancer cell systems. Overexpression of MEK5 in MCF-7 cells promoted both hormone-dependent and hormone-independent tumorigenesis in vitro and in vivo and conferred endocrine therapy resistance to previously sensitive breast cancer cells. Expression of MEK5 suppressed estrogen receptor (ER)α, but not ER-β protein levels, and abrogated downstream estrogen response element (ERE) transcriptional activity and ER-mediated gene transcription. Global gene expression changes associated with upregulation of MEK5 included increased activation of ER-α independent growth signaling pathways and promotion of epithelial-to-mesenchymal transition (EMT) markers. Taken together, our findings show that the MEK5-ERK5 pathway mediates progression to an ER(-), mesenchymal and endocrine therapy resistant phenotype. Given the need for new clinical therapeutic targets, our results demonstrate the therapeutic potential of targeting the MEK5-ERK5 pathway in breast cancer.

Huaier aqueous extract suppresses human breast cancer cell proliferation through inhibition of estrogen receptor α signaling

Estrogen receptor α (ERα) has been reported to play a critical role in promoting the growth of breast tumor cells. In the present study, we explored the effect of Huaier extract on estrogen receptor α signaling in breast cancer cell lines. Our data demonstrated that Huaier extract effectively inhibited the proliferation of the MCF-7, T47D and ZR-75-1 human breast cancer cell lines. For the mechanism analysis, we demonstrated that Huaier extract significantly reduced the mRNA and protein levels of ERα in all three ERα-positive cell lines. The downregulation of ERα protein levels was correlated with activation of the proteasomes. We demonstrated that Huaier extract markedly decreased the expression of both ERα and its downstream genes, inhibited the estrogen-stimulated proliferation and reversed the estrogen-induced activation of the nuclear factor κB (NFκB) pathway. Our study provides evidence that Huaier extract is a novel estrogen receptor modulator and is a promising drug for the prevention and treatment of ERα-positive human breast cancers.

Nuclear receptor coactivator RAC3 inhibits autophagy

RAC3 is an oncogene naturally overexpressed in several tumors. Besides its role as coactivator, it can exert several protumoral cytoplasmic actions. Autophagy was found to act either as a tumor suppressor during the early stages of tumor development, or as a protector of the tumor cell in later stages under hypoxic conditions. We found that RAC3 overexpression inhibits autophagy when induced by starvation or rapamycin and involves RAC3 nuclear translocation-dependent and -independent mechanisms. Moreover, hypoxia inhibits the RAC3 gene expression leading to the autophagy process, allowing tumor cells to survive until angiogenesis occurs. The interplay between RAC3, hypoxia, and autophagy could be an important mechanism for tumor progression and a good target for a future anticancer therapy.

The interaction between ER and NFκB in resistance to endocrine therapy

Endocrine therapy is a commonly used treatment for estrogen receptor (ER)-positive breast cancer. Although endocrine therapy has a favorable outcome in many patients, development of resistance is common. Recent studies have shown that NFκB, a transcription factor regulating a wide variety of cellular processes, might play a role in the development of endocrine resistance. The precise interaction between ER and NFκB and how this contributes to the attenuated responsiveness of ER-positive breast cancer cells to hormonal treatment remains unclear. This review provides an overview of the mechanisms of action for both transcription factors and focuses on the current knowledge explaining how ER and NFκB affect each other's activity and how this cross-talk might contribute to the development of an endocrine resistance phenotype in breast cancer cells.

Altered death receptor signaling promotes epithelial-to-mesenchymal transition and acquired chemoresistance

Altered death receptor signaling and resistance to subsequent apoptosis is an important clinical resistance mechanism. Here, we investigated the role of death receptor resistance in breast cancer progression. Resistance of the estrogen receptor alpha (ER)-positive, chemosensitive MCF7 breast cancer cell line to tumor necrosis factor (TNF) was associated with loss of ER expression and a multi-drug resistant phenotype. Changes in three major pathways were involved in this transition to a multidrug resistance phenotype: ER, Death Receptor and epithelial to mesenchymal transition (EMT). Resistant cells exhibited altered ER signaling, resulting in decreased ER target gene expression. The death receptor pathway was significantly altered, blocking extrinsic apoptosis and increasing NF-kappaB survival signaling. TNF resistance promoted EMT changes, resulting in a more aggressive phenotype. This first report identifying specific mechanisms underlying acquired resistance to TNF could lead to a better understanding of the progression of breast cancer in response to chemotherapy treatment.

Notch and Mef2 synergize to promote proliferation and metastasis through JNK signal activation in Drosophila

Genetic analyses in Drosophila revealed a synergy between Notch and the pleiotropic transcription factor Mef2 (myocyte enhancer factor 2), which profoundly influences proliferation and metastasis. We show that these hyperproliferative and invasive Drosophila phenotypes are attributed to upregulation of eiger, a member of the tumour necrosis factor superfamily of ligands, and the consequent activation of Jun N-terminal kinase signalling, which in turn triggers the expression of the invasive marker MMP1. Expression studies in human breast tumour samples demonstrate correlation between Notch and Mef2 paralogues and support the notion that Notch-MEF2 synergy may be significant for modulating human mammary oncogenesis.

Regulation of SVEP1 gene expression by 17β-estradiol and TNFα in pre-osteoblastic and mammary adenocarcinoma cells

Breast cancer is one of several tumors, including prostate, thyroid and kidney, which display a remarkable predilection for metastasis to bone. The preference to metastasize to bone by tumor cells relies on specific interactions among tumor cells, bone marrow microenvironment and bone cells. Osteomimicry is postulated to enable the survival of tumor cells in the bone tissue. Using gene profiling array and RT-PCR we demonstrated the message expression of few bone matrix proteins in mammary adenocarcinoma cells as well as that of cell adhesion molecules (CAMs). A CAM molecule, named SVEP1, was previously shown to be expressed in osteoblastic cells both in vivo and in vitro mediating cell adhesion in the bone-marrow niches. Both estradiol (17βE(2)) and TNFα regulate the expression of adhesion molecules and act in bone-cancer-crosstalk. We focused on differential regulation of SVEP1 gene comparing pre-osteoblastic MBA-15 and mammary adenocarcinoma DA3 cells. 17βE(2) and TNFα activated SVEP1 promoter, increased its message and protein levels in both cell types. Using chromatin immunoprecipitation assay, we quantified SVEP1 promoter occupancy by transcription factors; TFIIB, ERα, NF-κB, Sp1 and their binding was also regulated by both factors. By comparing pre-osteoblastic with mammary adenocarcinoma cells, the study expands our understanding of SVEP1 gene expression regulation and it sheds light on its involvement in bone-cancer-microenvironment interactions.

Oncostatin M suppresses oestrogen receptor-α expression and is associated with poor outcome in human breast cancer

The most important clinical biomarker for breast cancer management is oestrogen receptor alpha (ERα). Tumours that express ER are candidates for endocrine therapy and are biologically less aggressive, while ER-negative tumours are largely treated with conventional chemotherapy and have a poor prognosis. Despite its significance, the mechanisms regulating ER expression are poorly understood. We hypothesised that the inflammatory cytokine oncostatin M (OSM) can downregulate ER expression in breast cancer. Recombinant OSM potently suppressed ER protein and mRNA expression in vitro in a dose- and time-dependent manner in two human ER+ breast cancer cell lines, MCF7 and T47D. This was dependent on the expression of OSM receptor beta (OSMRβ) and could be blocked by inhibition of the MEKK1/2 mitogen-activated protein kinases. ER loss was also necessary for maximal OSM-induced signal transduction and migratory activity. In vivo, high expression of OSM and OSMR mRNA (determined by RT-PCR) was associated with reduced ER (P<0.01) and progesterone receptor (P<0.05) protein levels in a cohort of 70 invasive breast cancers. High OSM and OSMR mRNA expression was also associated with low expression of ESR1 (ER, P<0.0001) and ER-regulated genes in a previously published breast cancer gene expression dataset (n=321 cases). In the latter cohort, high OSMR expression was associated with shorter recurrence-free and overall survival in univariate (P<0.0001) and multivariate (P=0.022) analyses. OSM signalling may be a novel factor causing suppression of ER and disease progression in breast cancer.

Minireview: Inflammation: an instigator of more aggressive estrogen receptor (ER) positive breast cancers

Approximately 75% of breast tumors express the estrogen receptor (ER), and women with these tumors will receive endocrine therapy. Unfortunately, up to 50% of these patients will fail ER-targeted therapies due to either de novo or acquired resistance. ER-positive tumors can be classified based on gene expression profiles into Luminal A- and Luminal B-intrinsic subtypes, with distinctly different responses to endocrine therapy and overall patient outcome. However, the underlying biology causing this tumor heterogeneity has yet to become clear. This review will explore the role of inflammation as a risk factor in breast cancer as well as a player in the development of more aggressive, therapy-resistant ER-positive breast cancers. First, breast cancer risk factors, such as obesity and mammary gland involution after pregnancy, which can foster an inflammatory microenvironment within the breast, will be described. Second, inflammatory components of the tumor microenvironment, including tumor-associated macrophages and proinflammatory cytokines, which can act on nearby breast cancer cells and modulate tumor phenotype, will be explored. Finally, activation of the nuclear factor κB (NF-κB) pathway and its cross talk with ER in the regulation of key genes in the promotion of more aggressive breast cancers will be reviewed. From these multiple lines of evidence, we propose that inflammation may promote more aggressive ER-positive tumors and that combination therapy targeting both inflammation and estrogen production or actions could benefit a significant portion of women whose ER-positive breast tumors fail to respond to endocrine therapy.

Cyclin D1 is a NF-κB corepressor

NF-κB regulates the expression of Cyclin D1 (CD1), while RAC3 is an NF-κB coactivator that enhances its transcriptional activity. In this work, we investigated the regulatory role of CD1 on NF-κB activity. We found that CD1 inhibits NF-κB transcriptional activity through a corepressor function that can be reverted by over-expressing RAC3. In both, tumoral and non-tumoral cells, the expression pattern of RAC3 and CD1 is regulated by the cell cycle, showing a gap between the maximal expression levels of each protein. The individual increase, by transfection, of either CD1 or RAC3 enhances cell proliferation. However the simultaneous and constitutive over-expression of both proteins has an inhibitory effect. Our results suggest that the relative amounts of CD1 and RAC3, and the timing of expression of these oncogenes could tilt the balance of tumor cell proliferation in response to external signals.

CBP mediates NF-κB-dependent histone acetylation and estrogen receptor recruitment to an estrogen response element in the BIRC3 promoter

Estrogen receptor (ER) and NF-κB are transcription factors with profound effects on breast cancer cell proliferation and survival. While many studies demonstrate that ER and NF-κB can repress each other, we previously identified a gene signature that is synergistically upregulated by these two factors in more aggressive luminal B breast tumors. Herein, we examine a novel mechanism of cross talk between ER and NF-κB that results in the upregulation of the antiapoptotic gene BIRC3 (also known as cIAP2). We demonstrate that NF-κB, acting through two response elements, is required for ER recruitment to an adjacent estrogen response element (ERE) in the BIRC3 promoter. This effect is accompanied by a major increase in NF-κB-dependent histone acetylation around the ERE. Interestingly, CBP, a histone acetyltransferase previously implicated in repressive interactions between ER and NF-κB, plays a permissive role by promoting histone acetylation and ER recruitment, as well as enhanced expression of BIRC3. These findings suggest a new gene regulatory mechanism by which inflammation and NF-κB activation can influence ER recruitment to inherently inactive ER binding sites. This fine-tuning mechanism may explain how two factors that generally repress each other's activity may work together on certain genes to promote breast cancer cell survival and tumor progression.

A new regulator of osteoclastogenesis: estrogen response element-binding protein in bone

The heterogeneous nuclear ribonucleoprotein (hnRNP)-like estrogen response element-binding protein (ERE-BP) competes with estrogen receptor α (ERα) for occupancy of estrogen response elements (EREs). Here we report that ERE-BP potently stimulates osteoclastogenesis. ERE-BP mRNA and protein were found to be expressed ubiquitously in bone. Overexpression of ERE-BP in cultured osteoblasts stimulated expression of the receptor activator of NF-κB ligand (RANKL) and decreased osteoprotegerin (OPG). The effect of ERE-BP on RANKL was shown to be transcriptional in transient transfection assay and competed with via the ER. Constitutive expression of ERE-BP increased the sensitivity of cells toward 1,25-dihydroxyvitamin D(3) stimulation of RANKL expression. In contrast, knockdown of ERE-BP in stromal ST-2 cells decreased basal RANKL promoter activity. Cocultures of ERE-BP lentivirus-transduced ST-2 cells with spleen monocytes induced formation of multinucleated osteoclasts (OCs) characterized by tartrate-resistant acid phosphatase, calcitonin receptors, and functional calcium resorption from bone slices. Although ERα competed with ERE-BP for an ERE in a dose-dependent manner, ERE-BP was an independent and potent regulator of RANKL and osteoclastogenesis. In preosteoclastic RAW cells, overexpression of ERE-BP increased RANK, upregulated NF-κB signaling, and enhanced differentiation toward a mature OC phenotype independent of RANKL. These results identify ERE-BP as a potent modulator of osteoclastogenesis. We hypothesize that ERE-BP may play a critical role in the regulation of bone homeostasis as a modulator of estrogen sensitivity as well as by direct action on the transcription of critical osteoclastogenic genes.