Is androgen receptor targeting an emerging treatment strategy for triple negative breast cancer?

Treatments Targeting the Androgen Receptor and Its Splice Variants in Breast Cancer

Breast cancer is a major cause of death worldwide. The complexity of endocrine regulation in breast cancer may allow the cancer cells to escape from a particular treatment and result in resistant and aggressive disease. These breast cancers usually have fewer treatment options. Targeted therapies for cancer patients may offer fewer adverse side effects because of specificity compared to conventional chemotherapy. Signaling pathways of nuclear receptors, such as the estrogen receptor (ER), have been intensively studied and used as therapeutic targets. Recently, the role of the androgen receptor (AR) in breast cancer is gaining greater attention as a therapeutic target and as a prognostic biomarker. The expression of constitutively active truncated AR splice variants in breast cancer is a possible mechanism contributing to treatment resistance. Therefore, targeting both the full-length AR and AR variants, either through the activation or suppression of AR function, depending on the status of the ER, progesterone receptor, or human epidermal growth factor receptor 2, may provide additional treatment options. Studies targeting AR in combination with other treatment strategies are ongoing in clinical trials. The determination of the status of nuclear receptors to classify and identify patient subgroups will facilitate optimized and targeted combination therapies.

Assessment of androgen receptor expression in breast cancer patients using 18 F-FDG PET/CT radiomics and clinicopathological characteristics

OBJECTIVE

In the present study, we mainly aimed to predict the expression of androgen receptor (AR) in breast cancer (BC) patients by combing radiomic features and clinicopathological factors in a non-invasive machine learning way.

MATERIALS AND METHODS

A total of 48 BC patients, who were initially diagnosed by ¹⁸F-FDG PET/CT, were retrospectively enrolled in this study. LIFEx software was used to extract radiomic features based on PET and CT data. The most useful predictive features were selected by the LASSO (least absolute shrinkage and selection operator) regression and t-test. Radiomic signatures and clinicopathologic characteristics were incorporated to develop a prediction model using multivariable logistic regression analysis. The receiver operating characteristic (ROC) curve, Hosmer-Lemeshow (H-L) test, and decision curve analysis (DCA) were conducted to assess the predictive efficiency of the model.

RESULTS

In the univariate analysis, the metabolic tumor volume (MTV) was significantly correlated with the expression of AR in BC patients (p < 0.05). However, there only existed feeble correlations between estrogen receptor (ER), progesterone receptor (PR), and AR status (p = 0.127, p = 0.061, respectively). Based on the binary logistic regression method, MTV, SHAPE_Sphericity_CT (CT Sphericity from SHAPE), and GLCM_Contrast_CT (CT Contrast from grey-level co-occurrence matrix) were included in the prediction model for AR expression. Among them, GLCM_Contrast_CT was an independent predictor of AR status (OR = 9.00, p = 0.018). The area under the curve (AUC) of ROC in this model was 0.832. The p-value of the H-L test was beyond 0.05.

CONCLUSIONS

A prediction model combining radiomic features and clinicopathological characteristics could be a promising approach to predict the expression of AR and noninvasively screen the BC patients who could benefit from anti-AR regimens.

Epigenetic reprogramming of cell cycle genes by ACK1 promotes breast cancer resistance to CDK4/6 inhibitor

Hormone receptor-positive, HER2-negative advanced breast cancers exhibit high sensitivity to CDK4/6 inhibitors such as palbociclib. However, most patients inevitably develop resistance, thus identification of new actionable therapeutic targets to overcome the recurrent disease is an urgent need. Immunohistochemical studies of tissue microarray revealed increased activation of non-receptor tyrosine kinase, ACK1 (also known as TNK2) in most of the breast cancer subtypes, independent of their hormone receptor status. Chromatin immunoprecipitation studies demonstrated that the nuclear target of activated ACK1, pY88-H4 epigenetic marks, were deposited at cell cycle genes, CCNB1, CCNB2 and CDC20, which in turn initiated their efficient transcription. Pharmacological inhibition of ACK1 using its inhibitor, (R)-9b dampened CCNB1, CCNB2 and CDC20 expression, caused G2/M arrest, culminating in regression of palbociclib-resistant breast tumor growth. Further, (R)-9b suppressed expression of CXCR4 receptor, which resulted in significant impairment of metastasis of breast cancer cells to lung. Overall, our pre-clinical data identifies activated ACK1 as an oncogene that epigenetically controls the cell cycle genes governing the G2/M transition in breast cancer cells. ACK1 inhibitor, (R)-9b could be a novel therapeutic option for the breast cancer patients that have developed resistance to CDK4/6 inhibitors.

Newly Developed Targeted Therapies Against the Androgen Receptor in Triple-Negative Breast Cancer: A Review

Among different types of breast cancers (BC), triple-negative BC (TNBC) amounts to 15% to 20% of breast malignancies. Three principal characteristics of TNBC cells are (i) extreme aggressiveness, (ii) absence of hormones, and (iii) growth factor receptors. Due to the lack or poor expression of the estrogen receptor, human epidermal growth factor receptor 2, and progesterone receptor, TNBC is resistant to hormones and endocrine therapies. Consequently, chemotherapy is currently used as the primary approach against TNBC. Expression of androgen receptor (AR) in carcinoma cells has been observed in a subset of patients with TNBC; therefore, inhibiting androgen signaling pathways holds promise for TNBC targeting. The new AR inhibitors have opened up new therapy possibilities for BC patients carrying AR-positive TNBC cells. Our group provides a comprehensive review of the structure and function of the AR and clinical evidence for targeting the cell's nuclear receptor in TNBC. We updated AR agonists, inhibitors, and antagonists. We also presented a new era of genetic manipulating CRISPR/Cas9 and nanotechnology as state-of-the-art approaches against AR to promote the efficiency of targeted therapy in TNBC. SIGNIFICANCE STATEMENT: The lack of effective treatment for triple-negative breast cancer is a health challenge. The main disadvantages of existing treatments are their side effects, due to their nonspecific targeting. Molecular targeting of cellular receptors, such as androgen receptors, increased expression in malignant tissues, significantly improving the survival rate of breast cancer patients.

Potential Therapeutic Targets for Luminal Androgen Receptor Breast Cancer: What We Know so Far

Luminal Androgen Receptor Breast Cancers (LAR BCs) are characterized by a triple negative phenotype and by the expression of Androgen Receptor (AR), coupled with luminal-like genomic features. This unique BC subtype, accounting for about 10% of all triple negative BC, has raised considerable interest given its ill-defined clinical behavior and the chance to exploit AR as a therapeutic target. The complexity of AR activity in BC cells, as revealed by decades of mechanistic studies, holds promise to offer additional therapeutic options beyond mere AR inhibition. Indeed, preclinical and translational evidence showed that several pathways and mediators, including PI3K/mToR, HER2, BRCA1, cell cycle and immune modulation, can be tackled in LAR BCs. Moving from bench to bedside, several clinical trials tested anti-androgen therapies in LAR BCs, but their results are inconsistent and often disappointing. More recently, studies exploring combinations of anti-androgen agents with other targeted therapies have been designed and are currently ongoing. While the results from these trials are awaited, a concerted effort will be needed to find the biological vulnerabilities of LAR BCs which may disclose new and effective therapeutic targets, eventually improving patients' outcomes.

Adaptation to Hypoxia May Promote Therapeutic Resistance to Androgen Receptor Inhibition in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) surpasses other BC subtypes as the most challenging to treat due to its lack of traditional BC biomarkers. Nearly 30% of TNBC patients express the androgen receptor (AR), and the blockade of androgen production and AR signaling have been the cornerstones of therapies for AR-positive TNBC. However, the majority of women are resistant to AR-targeted therapy, which is a major impediment to improving outcomes for the AR-positive TNBC subpopulation. The hypoxia signaling cascade is frequently activated in the tumor microenvironment in response to low oxygen levels; activation of the hypoxia signaling cascade allows tumors to survive despite hypoxia-mediated interference with cellular metabolism. The activation of hypoxia signaling networks in TNBC promotes resistance to most anticancer drugs including AR inhibitors. The activation of hypoxia network signaling occurs more frequently in TNBC compared to other BC subtypes. Herein, we examine the (1) interplay between hypoxia signaling networks and AR and (2) whether hypoxia and hypoxic stress adaptive pathways promote the emergence of resistance to therapies that target AR. We also pose the well-supported question, “Can the efficacy of androgen-/AR-targeted treatments be enhanced by co-targeting hypoxia?” By critically examining the evidence and the complex entwinement of these two oncogenic pathways, we argue that the simultaneous targeting of androgen biosynthesis/AR signaling and hypoxia may enhance the sensitivity of AR-positive TNBCs to AR-targeted treatments, derail the emergence of therapy resistance, and improve patient outcomes.

Diverse role of androgen action in human breast cancer

Breast cancer is a hormone-dependent cancer, and sex steroids play a pivotal role in breast cancer progression. Estrogens are strongly associated with breast cancers, and the estrogen receptor (estrogen receptor α; ERα) is expressed in 70-80% of human breast carcinoma tissues. Although antiestrogen therapies (endocrine therapies) have significantly improved clinical outcomes in ERα-positive breast cancer patients, some patients experience recurrence after treatment. In addition, patients with breast carcinoma lacking ERα expression do not benefit from endocrine therapy. The androgen receptor (AR) is also expressed in >70% of breast carcinoma tissues. Growing evidence supports this novel therapeutic target for the treatment of triple-negative breast cancers that lack ERα, progesterone receptor, and human EGF receptor 2, and ERα-positive breast cancers, which are resistant to conventional endocrine therapy. However, the clinical significance of AR expression is still controversial and the biological function of androgens in breast cancers is unclear. In this review, we focus on the recent findings concerning androgen action in breast cancers and the contributions of androgens to improved breast cancer therapy.

Carcinogenesis of Triple-Negative Breast Cancer and Sex Steroid Hormones

Simple Summary

Triple-negative breast cancer (TNBC) lacks all of three treatment targets (estrogen receptor-α, ER-α; progesterone receptor, PgR; and human epidermal growth factor receptor 2, HER2) and is usually associated with a poor clinical outcome; however, several sex steroid receptors, such as androgen receptor (AR), ER-β, and G-protein-coupled estrogen receptor, are frequently expressed and their biological and clinical importance has been suggested. Despite the structural similarity between sex steroid hormones (androgens and estrogens) or receptors (AR and ER-β), similar signaling mechanisms of these hormones, and the coexistence of these hormones and their receptors in TNBC in a clinical setting, most studies or reviews focused on only one of these receptors, and rarely reviewed them in a comprehensive way. In this review, the carcinogenic or pathobiological role of sex steroid hormones in TNBC is considered, focusing on common and differing features of hormone actions.

Abstract

Triple-negative breast cancer (TNBC) lacks an effective treatment target and is usually associated with a poor clinical outcome; however, hormone unresponsiveness, which is the most important biological characteristic of TNBC, only means the lack of nuclear estrogenic signaling through the classical estrogen receptor (ER), ER-α. Several sex steroid receptors other than ER-α: androgen receptor (AR), second ER, ER-β, and non-nuclear receptors represented by G-protein-coupled estrogen receptor (GPER), are frequently expressed in TNBC and their biological and clinical importance has been suggested by a large number of studies. Despite the structural similarity between each sex steroid hormone (androgens and estrogens) or each receptor (AR and ER-β), and similarity in the signaling mechanisms of these hormones, most studies or reviews focused on one of these receptors, and rarely reviewed them in a comprehensive way. Considering the coexistence of these hormones and their receptors in TNBC in a clinical setting, a comprehensive viewpoint would be important to correctly understand the association between the carcinogenic mechanism or pathobiology of TNBC and sex steroid hormones. In this review, the carcinogenic or pathobiological role of sex steroid hormones in TNBC is considered, focusing on the common and divergent features of the action of these hormones.

Progress: Targeted Therapy, Immunotherapy, and New Chemotherapy Strategies in Advanced Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is one of the most aggressive subtypes of breast cancer, accounting for approximately 15% of cases, and is defined by the lack of expression of hormone receptors (estrogen and progesterone receptors) and lack of amplification or overexpression of human epidermal growth receptor 2 (HER2). Due to the lack of targets of hormone receptors and HER2, treatment of TNBC or advanced TNBC relies on conventional chemotherapeutic agents, but their efficacy and prognosis are poor. In patients with advanced TNBC, poorer outcomes are observed. Recently, with the launch of clinical trials and advancements in molecular studies, targeted therapy for signaling transduction pathways, immunotherapy for immune checkpoints, and new chemotherapy strategies have provided feasible or potential therapeutic options for advanced TNBC. This review aimed to summarize recent progress in targeted therapy, immunotherapy, and chemotherapy for advanced TNBC.

Role of androgen and microRNA in triple-negative breast cancer

Breast cancer (BC) is the most frequent type of malignancy affecting females worldwide. Molecular-based studies resulted in an identification of at least four subtypes of breast carcinoma, including luminal A and luminal B, Human growth factor receptor (HER-2)-enriched and triple-negative tumors (basal-like and normal breast-like). A proportion of BC cases are of the triple-negative breast cancer (TNBC) type. TNBC lacks the expression of estrogen receptor (ER), progesterone receptor (PR), and HER-2, and is known to express androgen receptor (AR) at considerable levels. AR has been shown to promote the progression of TNBC. However, the exact mechanisms have yet to be unraveled. One of these mechanisms could be through regulating the expression of microRNA (miRNA) molecules, which play an important regulatory role in BC through post-transcriptional gene silencing. Activation of AR controls the expression of miRNA molecules, which target selective mRNAs, consequently, affecting protein expression. In this review we attempt to elucidate the relations between AR and miRNA in TNBC.

Distribution and characteristics of androgen receptor (AR) in breast cancer among women in Addis Ababa, Ethiopia: A cross sectional study

Evaluation of the role of androgen receptor (AR) in the biology of breast cancer is an emerging area of research. There are compelling evidences that AR expression may be used to further refine breast cancer molecular subtyping with prognostic and therapeutic implications. Many studies indicated co-expression of AR with the hormonal receptors in breast cancer has a favorable prognosis. AR is also investigated by many researchers as a potential therapeutic target in treatment of breast cancer. Studies on the frequency and distribution of AR in breast cancer among Africans is barely available. Given the heightened interest to understand its role in breast cancer, we determined AR expression and assessed its association with clinicopathological parameters among Ethiopian women. In this study, 112 newly diagnosed patient with invasive breast cancer at Tikur Anbessa Specialized Hospital were enrolled. Immunohistochemical assessment of AR, ER, PR, Ki67 and HER2 were performed using tissue microarrays (TMA) constructed from their primary tumor block. Out of the 112 participants, 91 (81%) were positive for AR expression and the remaining 21 participants (19%) were negative for AR expression. Expression of AR in ER+, HER2+ and TNBC cases were 93%, 83% and 48% respectively. Our study reveals AR is expressed in a significant number of breast cancers patients and this may indicate that breast cancers cases in Ethiopia have favorable prognosis and could benefit from progresses in AR targeted treatments. Since AR expression has important consequences on the prognosis and treatment of breast cancer, further studies with an increased number of participants is necessary to confirm our reports.

Androgen Receptor in Breast Cancer-Clinical and Preclinical Research Insights

The Androgen Receptor (AR) is emerging as an important factor in the pathogenesis of breast cancer (BC), which is the most common malignancy among females worldwide. The concordance of more than 70% of AR expression in primary and metastatic breast tumors implies that AR may be a new marker and a potential therapeutic target among AR-positive breast cancer patients. Biological insight into AR-positive breast cancer reveals that AR may cross-talk with several vital signaling pathways, including key molecules and receptors. AR exhibits different behavior depending on the breast cancer subtype. Preliminary clinical research using AR-targeted drugs, which have already been FDA-approved for prostate cancer (PC), has given promising results for AR-positive breast cancer patients. However, since the prognostic and predictive value of AR positivity remains uncertain, it is difficult to identify and stratify patients that would benefit from AR-targeted therapies. Herein, through a review of preclinical studies, clinical studies, and clinical trials, we summarize the biology of AR, its prognostic and predictive value, as well as its therapeutic implications by breast cancer molecular subtype.

Androgen Receptors in Resected Ductal Carcinoma In Situ of Breast: Novel Insights With Possible Implications for Testing and Targeted Endocrine Chemoprevention Trials

Mammary ductal carcinoma in situ (DCIS) is classically treated by combinations of excision, radiation, and endocrine therapy, based upon the specific needs of individual patients. Estrogen receptor (ER) status is generally assessed by immunohistochemistry (IHC) in newly diagnosed cases of DCIS, and endocrine therapy in this setting is thought to be chemopreventive. The potential impact of androgens on mammary carcinogenesis has been studied in recent years, and several authors have proposed androgen receptor (AR) IHC testing and targeted antiandrogenic therapy in patients with locally advanced or metastatic triple-negative invasive breast cancer (ie, negative for ER and progesterone receptor and HER-2). Very little has been published on AR in DCIS. We report results of AR IHC on archival tissue blocks from 221 adult female patients, each of whom underwent definitive breast resection of DCIS. Of the 221 cases, 72 (33%) were shown to express AR in their DCIS at or above the 10% threshold often used for invasive carcinoma. AR expression was seen in all grades of DCIS. Of the 72 positive AR cases, 21 (29%) were ER negative, corresponding to 10% (21/221) of all patients. The majority of the AR-positive cases were high grade, and the most common histologic subtype in this subset was a solid growth pattern with apocrine features. Early data from clinical trials evaluating AR antagonists in invasive/metastatic triple-negative breast cancer suggest that some patients may benefit from androgen blockade. IHC testing and potential clinical trials of AR antagonists for chemoprevention in patients with AR-positive and ER-negative DCIS could be considered.

Estrogen receptor beta increases sensitivity to enzalutamide in androgen receptor-positive triple-negative breast cancer

PURPOSE

Androgen receptor (AR) is playing an important role in the progression of a subset of TNBC. We evaluated the impact of ERβ expression along with anti-AR drugs in AR-positive TNBC.

METHODS

ERβ expression was examined in AR-positive TNBC cell line using MTT assay, scratch and Annexin V-FITC assay in the presence or absence of anti-androgens. Protein levels of involved molecules were assessed using Western blot. Receptors' localization was detected by immunofluorescence and their physical association was examined using proximity ligation assay (PLA), which enables the visualization of interacting proteins in fixed cells and tissues.

RESULTS

Transient transfection of ERβ in MDA-MB 453 AR-positive TNBC cell line significantly inhibited cell proliferation, metastatic potential and induced apoptosis. ERβ expression reversed the aggravating role of AR in both indirect and direct ways. Indirectly, ERβ decreased AR activation through the inhibition of PI3K/AKT signaling pathway. Directly, ERβ formed heterodimers with AR in MDA-MB 453 cells and in human tissue samples impeding AR from forming homodimers. Enzalutamide is a more potent anti-androgen in AR + TNBC compared to bicalutamide. ERβ expression increased the sensitivity of MDA-MB 453 cells to anti-androgens and especially to enzalutamide. The administration of enzalutamide enhanced AR:ERβ heterodimers formation increasing the anti-tumor capacity of ERβ.

CONCLUSIONS

Collectively, our results provide evidence for a novel mechanism by which ERβ exerts oncosuppressive effect in AR-positive TBNC through direct and indirect interactions with AR. Moreover, ERβ expression may identify a new subset of TNBC that would respond more favorable to anti-androgens.

AR-PDEF pathway promotes tumour proliferation and upregulates MYC-mediated gene transcription by promoting MAD1 degradation in ER-negative breast cancer

Background

Androgen receptor (AR) is expressed in 60%~ 70% oestrogen receptor (ER)-negative breast cancer (BC) cases and promotes the growth of this cancer subtype. Expression of prostate-derived Ets factor (PDEF), a transcription factor, is highly restricted to epithelial cells in hormone-regulated tissues. MYC and its negative regulator MAD1 play an important role in BC progression. Previously, we found that PDEF expression is strongly correlated with AR expression. However, the relationship between AR and PDEF and the function of PDEF in ER-negative BC proliferation are unclear.

Methods

AR and PDEF expression in ER-negative BC tissues and cell lines was determined by performing immunohistochemistry or western blotting. Protein expression levels and location were analysed by performing western blotting, RT-qPCR and immunofluorescence staining. Co-immunoprecipitation and chromatin immunoprecipitation assays were performed to validate the regulation of AR–PDEF–MAD1–MYC axis. Moreover, the effect of AR and PDEF on BC progression was investigated both in vitro and in vivo.

Results

We found that PDEF was overexpressed in ER-negative BC tissues and cell lines and appeared to function as an oncogene. PDEF expression levels were strongly correlated with AR expression in ER-negative BC, and PDEF transcription was positively regulated by AR. PDEF upregulated MYC-mediated gene transcription by promoting MAD1 degradation in ER-negative BC. Finally, we found that compared with the inhibition of AR expression alone, simultaneous inhibition of AR and PDEF expression further suppressed tumour proliferation both in vitro and in vivo.

Conclusions

Our data highlight the role of the AR–PDEF–MAD1–MYC axis in BC progression and suggest that PDEF can be used as a new clinical therapeutic target for treating ER-negative BC.

Electronic supplementary material

The online version of this article (10.1186/s12943-018-0883-0) contains supplementary material, which is available to authorized users.

The preoperative prognostic nutritional index is a predictive and prognostic factor of high-grade serous ovarian cancer

BACKGROUND

The aim of our study was to investigate whether an inflammation-based prognostic score, the prognostic nutritional index (PNI), was associated with clinical characteristics and prognosis in patients with high-grade serous ovarian cancer (HGSC).

METHODS

We retrospectively investigated 875 patients who underwent primary staging or debulking surgery for HGSC between April 2005 and June 2013 at our institution. None of these patients received neoadjuvant chemotherapy. Preoperative PNI was calculated as serum albumin (g/L) + 0.005 × lymphocyte count (per mm³). The optimal PNI cutoff value for overall survival (OS) was identified using the online tool "Cutoff Finder". Clinical characteristics and PNI were compared with chi-square or Fisher's exact tests, as appropriate. The impact of PNI on OS was analyzed using the Kaplan-Meier method and Cox proportional hazards model.

RESULTS

The median (range) PNI was 46.2 (29.2-67.7). The 45.45 cutoff value discriminated patients into the high-PNI and low-PNI groups. A low preoperative PNI was associated with an advanced FIGO stage, increased CA125 level, more extensive ascites, residual disease and platinum resistance. For univariate analyses, a high PNI was associated with increased OS (p < 0.001). In multivariate analyses, the PNI remained an independent predictor of OS as a continuous variable (p = 0.021) but not as dichotomized groups (p = 0.346).

CONCLUSION

Our study demonstrated that the PNI could be a predictive and prognostic parameter for HGSC.

The cellular and molecular effects of the androgen receptor agonist, Cl-4AS-1, on breast cancer cells

PURPOSE

The androgen receptor (AR) has attracted attention in the treatment of breast cancer. Due to the undesirable side effects of AR agonists, attempts have been undertaken to develop selective AR modulators. One of these compounds is Cl-4AS-1. This study examined this compound more closely at the cellular and molecular levels.

METHODS

Three different breast cancer cell lines were utilized, namely the luminal MCF-7 cells, the molecular apocrine MDA-MB-453 cells, and the triple negative, basal MDA-MB-231 cells.

RESULTS

High and significant concordance between dihydrotestosterone (DHT) and Cl-4AS-1 in regulation of gene expression in MDA-MB-453 cells was found. However, some differences were noted including the expression of AR, which was upregulated by DHT, but not Cl-4AS-1. In addition, both DHT and Cl-4AS-1 caused a similar morphological change and reorganization of the actin structure of MDA-MB-453 cells into a mesenchymal phenotype. Treatment of cells with DHT resulted in induction of proliferation of MCF-7 and MDA-MB-453 cells, but no effect was observed on the growth of MDA-MB-231 cells. On the other hand, increasing doses of Cl-4AS-1 resulted in a dose-dependent inhibition on the growth of the three cell lines. This inhibition was a result of induction of apoptosis whereby Cl-4AS-1 caused a block in entry of cells into the S-phase followed by DNA degradation.

CONCLUSIONS

These results indicate that although Cl-4AS-1 has characteristics of classical AR agonist, it has dissimilar properties that may make it useful in treating breast cancer.

Clinical significance of androgen receptor expression in triple negative breast cancer-an immunohistochemistry study

Androgen receptor (AR) is closely associated with the occurrence and progression of breast cancer; however, the clinical significance of it in triple negative breast cancer (TNBC) has been controversial. There is a limited amount of research regarding the effect of neoadjuvant chemotherapy on AR expression. By examining the expression of AR in patients with TNBC, the aim of the present study is to explore the clinical significance of AR and provide evidence for AR-directed treatment in TNBC. A total of 188 patients with primary TNBC with complete medical records were included in this retrospective study. Tumor sections from 41 patients (21.8%) were positive for AR, which was more often detected in small tumors (P=0.042) and cases with no lymph node involvement (P=0.032). Among them, 102 were treated with neoadjuvant chemotherapy (NAC). A total of 17 patients (16.7%) exhibited pathological complete response. However, the patient response was irrelevant to AR expression. Matched pathological tissues before and after NAC were collected for 49 cases, suggesting an enrichment of AR-expressing tumors following chemotherapy (P=0.008). Further analysis indicated that AR expression had no correlation with the disease-free and overall survival of patients with general TNBC; rather, it predicted a poor survival of the patients with stage III TNBC in comparison with those at earlier stages (P=0.035). AR expression occurs more often in small TNBC tumors or in cases with no lymph node metastasis. It is associated with a poor prognosis of the patients with advanced stages of tumors.

PIK3CA mutation, reduced AKT serine 473 phosphorylation, and increased ERα serine 167 phosphorylation are positive prognostic indicators in postmenopausal estrogen receptor-positive early breast cancer

Although endocrine therapy is the most important treatment option in estrogen receptor (ER)-positive breast cancer, new strategies, such as molecular targeted agents together with endocrine therapy are required to improve survival. PIK3CA is the most frequent mutated gene in ER-positive early breast cancers, and PIK3CA mutation status is reported to affect activation of AKT and ERα. Moreover, recent studies demonstrate that patients had a better prognosis when tumors expressed ER, androgen receptor (AR), and vitamin D receptor (VDR). In this study, we examined expression of AR and VDR, phosphorylation of AKT serine (Ser) 473 (AKT phospho-Ser473) and ERα Ser167 (ERα phospho-Ser167) by immunohistochemistry in ER-positive, HER2-negative early breast cancer. PIK3CA gene mutations were also detected in genomic DNA extracted from tumor blocks. Correlations between these biological markers, clinicopathological factors and prognosis were analyzed. Levels of AKT phospho-Ser473 were significantly higher in premenopausal women than in postmenopausal women. In contrast, AR expression was significantly higher in postmenopausal women than in premenopausal women. PIK3CA mutations were detected in 47% in premenopausal women and 47% in postmenopausal women. Postmenopausal women with PIK3CA wild-type tumors had significantly worse disease-free survival than patients with PIK3CA mutant tumors. Low levels of AKT phospho-Ser473 and high levels of ERα phospho-Ser167 were strongly associated with increased disease-free survival in postmenopausal women. Evaluation of ERα activation, in addition to PIK3CA mutation status, might be helpful in identifying patients who are likely to benefit from endocrine therapy alone versus those who are not in postmenopausal ER-positive early breast cancer.

Risk Factors and Preventions of Breast Cancer

Breast cancer is the second leading cause of cancer deaths among women. The development of breast cancer is a multi-step process involving multiple cell types, and its prevention remains challenging in the world. Early diagnosis of breast cancer is one of the best approaches to prevent this disease. In some developed countries, the 5-year relative survival rate of breast cancer patients is above 80% due to early prevention. In the recent decade, great progress has been made in the understanding of breast cancer as well as in the development of preventative methods. The pathogenesis and tumor drug-resistant mechanisms are revealed by discovering breast cancer stem cells, and many genes are found related to breast cancer. Currently, people have more drug options for the chemoprevention of breast cancer, while biological prevention has been recently developed to improve patients' quality of life. In this review, we will summarize key studies of pathogenesis, related genes, risk factors and preventative methods on breast cancer over the past years. These findings represent a small step in the long fight against breast cancer.

Androgen Receptor Immunohistochemistry as a Companion Diagnostic Approach to Predict Clinical Response to Enzalutamide in Triple-Negative Breast Cancer

Purpose

The androgen receptor (AR) is increasingly recognized as a potential biomarker for identifying a subset of patients with possible hormonally driven triple-negative breast cancer (TNBC). However, its performance as a companion diagnostic remains elusive. Thus, we evaluated AR expression by immunohistochemistry in patients with advanced TNBC before treatment with the AR inhibitor enzalutamide.

Methods

We optimized and validated immunohistochemistry assays in breast and prostate cancer cell lines and tissues using two commercial AR monoclonal antibodies (SP107 and AR441). AR expression was then examined in patients with advanced TNBC enrolled in a phase II study of enzalutamide (ClinicalTrials.gov identifier: NCT01889238) on archived or fresh tissue before treatment. Association with clinical response was assessed by sensitivity, specificity, positive predictive value (PPV), drop-out rate, and survival.

Results

AR expression was detected in 80% and 63% of breast cancer tissue using SP107 and AR441, respectively. SP107 was selected for additional analyses because of its higher sensitivity and robustness. Total AR nuclear staining demonstrated the best accuracy in predicting clinical response (area under receiver operating characteristic curve, 0.72; P = .0001). At a threshold of 10%, 74.6% of patients were AR positive, leading to 30% PPV, 90% sensitivity, and 30% specificity. These patients showed a significantly higher median progression-free survival (hazard ratio, 0.56; 95% CI, 0.36 to 0.88; P = .011) and overall survival (hazard ratio, 0.54; 95% CI, 0.32 to 0.91; P = .019) compared with those with AR-negative (< 10%) TNBC.

Conclusion

At a threshold of ≥ 10% nuclear expression, the AR was associated with TNBC response to enzalutamide. However, the modest PPV may restrict its clinical application, and additional diagnostic tools may be helpful for improved patient selection.

The prognostic significance of combined androgen receptor, E-Cadherin, Ki67 and CK5/6 expression in patients with triple negative breast cancer

Background

Triple Negative Breast Cancer (TNBC) represents a heterogeneous group of tumors with poor prognosis owing to aggressive tumor biology and lack of targeted therapies. No clear prognostic biomarkers have been identified to date for this subgroup.

Materials and Methods

In this retrospective study we evaluated the prognostic role of 4 different molecular determinants, including androgen receptor (AR), E-cadherin (CDH1), Ki67 index, and basal cytokeratins (CKs) 5/6, in a cohort of 99 patients with TNBC. All patients received neo/adjuvant chemotherapy (mostly anthracycline/taxane-based). Immunohistochemistry (IHC) was performed in formalin-fixed paraffin-embedded primary tumor samples. CDH1 expression was considered positive as ≥ 30% of the membrane cells staining. AR positivity was defined as > 10% of positive tumor cells. High Ki67 was defined as ≥20% positive tumor cells. CK5/6 expression was judged positive if the score was ≥1.

Results

The absence of AR expression was significantly associated with highly undifferentiated tumors. Univariate analyses showed that lack of expression of CDH1, tumor size and nodal status were significantly correlated with worse RFS and OS (p< 0.05). AR expression and low Ki67 showed a trend towards better RFS and OS. Patients with absent CK5/6 expression in univariate and multivariate analyses had poorer RFS (p=0.02 and p=0.002, respectively) and OS (p=0.05 and p=0.02, respectively). Multivariate analysis showed an independent association between CDH1 expression and better RFS and OS (p< 0.05) beyond tumor size, nodal status, and grade. The Kaplan-Meier curves showed that patients with AR and CDH1 negative expression and high Ki-67 levels have a significant correlation with poor outcome.

Conclusions

Our study supports the use of IHC expression of AR, CDH1, Ki67, and CK5/6 as prognostic markers in TNBCs and suggests a link between their expression and prognosis and may help to stratify TNBC patients in different prognostic classes.

Molecular alterations in triple-negative breast cancer-the road to new treatment strategies

Triple-negative breast cancer is a heterogeneous disease and specific therapies have not been available for a long time. Therefore, conventional chemotherapy is still considered the clinical state of the art. Different subgroups of triple-negative breast cancer have been identified on the basis of protein expression, mRNA signatures, and genomic alterations. Important elements of triple-negative breast cancer biology include high proliferative activity, an increased immunological infiltrate, a basal-like and a mesenchymal phenotype, and deficiency in homologous recombination, which is in part associated with loss of BRCA1 or BRCA2 function. A minority of triple-negative tumours express luminal markers, such as androgen receptors, and have a lower proliferative activity. These biological subgroups are overlapping and currently cannot be combined into a unified model of triple-negative breast cancer biology. Nevertheless, the molecular analysis of this disease has identified potential options for targeted therapeutic intervention. This has led to promising clinical strategies, including modified chemotherapy approaches targeting the DNA damage response, angiogenesis inhibitors, immune checkpoint inhibitors, or even anti-androgens, all of which are being evaluated in phase 1-3 clinical studies. This Series paper focuses on the most relevant clinical questions, summarises the results of recent clinical trials, and gives an overview of ongoing studies and trial concepts that will lead to a more refined therapy for this tumour type.

[Androgen receptors in breast cancer: Expression, value and therapeutic prospects]

Triple-negative (TN) breast cancer are characterized by lack of estrogen receptor (OR) and progesterone receptor (PR) expression, and the absence of overexpression of human epidermal growth factor receptor 2 (HER2). It is a heterogeneous group of tumors with a more pejorative prognosis than other subtypes of breast cancer. Androgen receptors (AR) are nuclear receptors whose expression varies from 80 to 85% of primary breast cancers and 60 to 75% of metastatic cancers. Among the TN breast cancers, the luminal androgen receptor (LAR) subtype expresses AR more frequently, up to 53% of the cases. AR are associated with lower tumor size, histological grade, Ki67, and lymph node involvement. The results of recent clinical trials evaluating anti-androgen therapies in locally advanced or metastatic TN breast cancer are promising. Many new therapies are tested, including enzalutamide or abiraterone acetate, and numerous therapeutic combinations including PI3K/AKT/mTOR inhibitors or CDK inhibitors. These therapies would allow an alternative treatment of patients with TN breast cancer for which there is often a therapeutic impasse.

A Tale of Two Signals: AR and WNT in Development and Tumorigenesis of Prostate and Mammary Gland

Prostate cancer (PCa) is one of the most common cancers and among the leading causes of cancer deaths for men in industrialized countries. It has long been recognized that the prostate is an androgen-dependent organ and PCa is an androgen-dependent disease. Androgen action is mediated by the androgen receptor (AR). Androgen deprivation therapy (ADT) is the standard treatment for metastatic PCa. However, almost all advanced PCa cases progress to castration-resistant prostate cancer (CRPC) after a period of ADT. A variety of mechanisms of progression from androgen-dependent PCa to CRPC under ADT have been postulated, but it remains largely unclear as to when and how castration resistance arises within prostate tumors. In addition, AR signaling may be modulated by extracellular factors among which are the cysteine-rich glycoproteins WNTs. The WNTs are capable of signaling through several pathways, the best-characterized being the canonical WNT/β-catenin/TCF-mediated canonical pathway. Recent studies from sequencing PCa genomes revealed that CRPC cells frequently harbor mutations in major components of the WNT/β-catenin pathway. Moreover, the finding of an interaction between β-catenin and AR suggests a possible mechanism of cross talk between WNT and androgen/AR signaling pathways. In this review, we discuss the current knowledge of both AR and WNT pathways in prostate development and tumorigenesis, and their interaction during development of CRPC. We also review the possible therapeutic application of drugs that target both AR and WNT/β-catenin pathways. Finally, we extend our review of AR and WNT signaling to the mammary gland system and breast cancer. We highlight that the role of AR signaling and its interaction with WNT signaling in these two hormone-related cancer types are highly context-dependent.

Triple-negative breast cancer: treatment challenges and solutions

Triple-negative breast cancers (TNBCs) are defined by the absence of estrogen and progesterone receptors and the absence of HER2 overexpression. These cancers represent a heterogeneous breast cancer subtype with a poor prognosis. Few systemic treatment options exist besides the use of chemotherapy (CT). The heterogeneity of the disease has limited the successful development of targeted therapy in unselected patient populations. Currently, there are no approved targeted therapies for TNBC. However, intense research is ongoing to identify specific targets and develop additional and better systemic treatment options. Standard adjuvant and neoadjuvant regimens include anthracyclines, cyclophosphamide, and taxanes. Platinum-based CT has been proposed as another CT option of interest in TNBC. We review the role of this therapy in general, and particularly in patients carrying BRCA germ-line mutations. Available data concerning the role of platinum-based CT in TNBC were acquired primarily in the neoadjuvant setting. The routine use of platinum-based CT is not yet recommended by available guidelines. Many studies have reported the molecular characterization of TNBCs. Several actionable targets have been identified. Novel therapeutic strategies are currently being tested in clinical trials based on promising results observed in preclinical studies. These targets include androgen receptor, EGFR, PARP, FGFR, and the angiogenic pathway. We review the recent data on experimental drugs in this field. We also discuss the recent data concerning immunologic checkpoint inhibitors.

A clinically applicable molecular classification for high-grade serous ovarian cancer based on hormone receptor expression

To establish an effective hormone receptor-based molecular classification of high-grade serous ovarian cancer (HGSC), we retrospectively examined 875 consecutive HGSC patients who underwent primary surgery at our hospital and constructed tissue microarrays from these specimens. The expression levels of the hormone receptors were as follows: ER 64.4%, PR 12.6%, AR 35.6%, FSHR 54.5%, LHR 34.8%, and GnRHR 88.3%. Based on clustering of their expression patterns, we classified patients into five subgroups with distinctive clinical features (PR+, PR - ER + AR+, PR - ER + AR-, PR - ER - AR+, and PR - ER - AR-). Patients in the PR + group were younger compared to those in the other groups (p < 0.001). More patients were of advanced stage in the PR - ER + AR- group than the other groups (p = 0.020). A greater proportion of patients were sensitive to platinum-based chemotherapy in the PR - ER - AR + group compared with the other groups (p = 0.034). A trend of increasing risk of death was observed among these subgroups (p < 0.001). In the multivariate analysis, patients also had orderly increased hazard ratios for death in the PR + (HR = 2.256, 95% CI, 0.983-5.175), PR - ER + AR + (HR = 2.188, 95% CI, 1.004-4.796), PR - ER - AR- (HR = 2.316, 95% CI, 1.097-5.082) and PR - ER + AR- (HR = 2.928, 95% CI, 1.366-6.276) subgroups compared to the PR - ER - AR+ subgroup. Our classification could help predict patient clinical outcomes, guide individual treatments and stratify patients in future clinical trials.

Vitamin D and androgen receptor-targeted therapy for triple-negative breast cancer

Anti-estrogen and anti-HER2 treatments have been among the first and most successful examples of targeted therapy for breast cancer (BC). However, the treatment of triple-negative BC (TNBC) that lack estrogen receptor expression or HER2 amplification remains a major challenge. We previously discovered that approximately two-thirds of TNBCs express vitamin D receptor (VDR) and/or androgen receptor (AR) and hypothesized that TNBCs co-expressing AR and VDR (HR2-av TNBC) could be treated by targeting both of these hormone receptors. To evaluate the feasibility of VDR/AR-targeted therapy in TNBC, we characterized 15 different BC lines and identified 2 HR2-av TNBC lines and examined the changes in their phenotype, viability, and proliferation after VDR and AR-targeted treatment. Treatment of BC cell lines with VDR or AR agonists inhibited cell viability in a receptor-dependent manner, and their combination appeared to inhibit cell viability additively. Moreover, cell viability was further decreased when AR/VDR agonist hormones were combined with chemotherapeutic drugs. The mechanisms of inhibition by AR/VDR agonist hormones included cell cycle arrest and apoptosis in TNBC cell lines. In addition, AR/VDR agonist hormones induced differentiation and inhibited cancer stem cells (CSCs) measured by reduction in tumorsphere formation efficiency, high aldehyde dehydrogenase activity, and CSC markers. Surprisingly, we found that AR antagonists inhibited proliferation of most BC cell lines in an AR-independent manner, raising questions regarding their mechanism of action. In summary, AR/VDR-targeted agonist hormone therapy can inhibit HR2-av TNBC through multiple mechanisms in a receptor-dependent manner and can be combined with chemotherapy.

Targeting Androgen/Estrogen Receptors Crosstalk in Cancer

The actions of estrogens are mediated by estrogen receptors, ERα and ERβ. Recent genomic landscaping of ERα- and ERβ-binding sites has revealed important distinctions regarding their transcriptional activity. ERβ and its isoforms have been correlated with endocrine treatment responsiveness in breast tumors, while post-translational modifications, receptor dimerization patterns, and subcellular localization are increasingly recognized as crucial modulators in prostate carcinogenesis. Androgen receptor (AR) is essential for the development and progression of prostate cancer as well as of certain breast cancer types. The balance between the activity of these two hormone receptors and their molecular interactions in different clinical settings is influenced by several coregulators. This comprises a dynamic regulatory network enhancing or limiting the activity of AR-directed treatments in breast and prostate tumorigenesis. In this review, we discuss the molecular background regarding the therapeutic targeting of androgen/estrogen receptor crosstalk in breast and prostate cancer.

MiRNAs and Other Epigenetic Changes as Biomarkers in Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is characterised by the lack of receptors for estrogen (ER), progesterone (PR), and human epidermal growth factor 2 (HER2). Since it cannot be treated by current endocrine therapies which target these receptors and due to its aggressive nature, it has one of the worst prognoses of all breast cancer subtypes. The only treatments remain chemo- and/or radio-therapy and surgery and because of this, novel biomarkers or treatment targets are urgently required to improve disease outcomes. MicroRNAs represent an attractive candidate for targeted therapies against TNBC, due to their natural ability to act as antisense interactors and regulators of entire gene sets involved in malignancy and their superiority over mRNA profiling to accurately classify disease. Here we review the current knowledge regarding miRNAs as biomarkers in TNBC and their potential use as therapeutic targets in this disease. Further, we review other epigenetic changes and interactions of these changes with microRNAs in this breast cancer subtype, which may lead to the discovery of new treatment targets for TNBC.

Androgen Receptor Biology in Triple Negative Breast Cancer: a Case for Classification as AR+ or Quadruple Negative Disease

Triple negative breast cancer (TNBC) is an aggressive breast cancer subtype that lacks estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2) amplification. Due to the absence of these receptors, TNBC does not respond to traditional endocrine or HER2-targeted therapies that improve patient prognosis in other breast cancer subtypes. TNBC has a poor prognosis, and currently, there are no effective targeted therapies. Some TNBC tumors express androgen receptor (AR) and may benefit from AR-targeted therapies. Here, we review the literature on AR in TNBC and propose that TNBC be further sub-classified as either AR+ TNBC or quadruple negative breast cancer since targeting AR may represent a viable therapeutic option for a subset of TNBC.