Expression of androgen receptors in primary breast cancer

Androgen receptor expression predicts beneficial tamoxifen response in oestrogen receptor-α-negative breast cancer

Background:

Although the androgen receptor (AR) is frequently expressed in breast cancer, its relevance in the disease is not fully understood. In addition, the relevance of AR in determining tamoxifen treatment efficiency requires evaluation.

Purpose:

To investigate the tamoxifen predictive relevance of the AR protein expression in breast cancer.

Methods

Patients were randomised to tamoxifen 40 mg daily for 2 or 5 years or to no endocrine treatment. Mean follow-up was 15 years. Hazard ratios were calculated with recurrence-free survival as end point.

Results:

In patients with oestrogen receptor (ER)-negative tumours, expression of AR predicted decreased recurrence rate with tamoxifen (hazard ratio (HR)=0.34; 95% confidence interval (CI)=0.14–0.81; P=0.015), whereas the opposite was seen in the AR− group (HR=2.92; 95% CI=1.16–7.31; P=0.022). Interaction test was significant P<0.001. Patients with triple-negative and AR+ tumours benefitted from tamoxifen treatment (HR=0.12; 95% CI=0.014–0.95 P=0.044), whereas patients with AR− tumours had worse outcome when treated with tamoxifen (HR=3.98; 95% CI=1.32–12.03; P=0.014). Interaction test was significant P=0.003. Patients with ER+ tumours showed benefit from tamoxifen treatment regardless of AR expression.

Conclusions:

AR can predict tamoxifen treatment benefit in patients with ER− tumours and triple-negative breast cancer.

Expression of androgen receptor splice variants in clinical breast cancers

The importance of androgen receptor (AR) signaling is increasingly being recognized in breast cancer, which has elicited clinical trials aimed at assessing the efficacy of androgen deprivation therapy (ADT) for metastatic disease. In prostate cancer, resistance to ADT is frequently associated with the emergence of androgen-independent splice variants of the AR (AR variants, AR-Vs) that lack the LBD and are constitutively active. Women with breast cancer may be prone to a similar phenomenon. Herein, we show that in addition to the prototypical transcript, the AR gene produces a diverse range of AR-V transcripts in primary breast tumors. The most frequently and highly expressed variant was AR-V7 (exons 1/2/3/CE3), which was detectable at the mRNA level in > 50% of all breast cancers and at the protein level in a subset of ERα-negative tumors. Functionally, AR-V7 is a constitutively active and ADT-resistant transcription factor that promotes growth and regulates a transcriptional program distinct from AR in ERα-negative breast cancer cells. Importantly, we provide ex vivo evidence that AR-V7 is upregulated by the AR antagonist enzalutamide in primary breast tumors. These findings have implications for treatment response in the ongoing clinical trials of ADT in breast cancer.

Beyond the C18 frontier: Androgen and glucocorticoid metabolism in breast cancer tissues: The role of non-typical steroid hormones in breast cancer development and progression

Breast cancer's hormonal dependence is well known and has been so for a long time. However in the last two decades great advances have been made in understanding the local metabolism of steroids within tissue. In the form of aromatase inhibition this is already one of the mainstays of breast cancer therapy. This review aims to summarise briefly what is known in terms of the metabolism of C18 steroids but perhaps more importantly to touch on the new developments regarding the importance of the metabolism of androgens and glucocorticoids in breast tissue. It is our hope that this review should provide the reader with a "birds eye view" of the current state of knowledge regarding localised steroid metabolism in the breast.

Abiraterone acetate, exemestane or the combination in postmenopausal patients with estrogen receptor-positive metastatic breast cancer

Resistance to nonsteroidal aromatase inhibitors is a major obstacle in the management of estrogen receptor-positive postmenopausal metastatic breast cancer. The addition of abiraterone acetate to exemestane did not improve clinical outcomes compared with exemestane alone in an androgen receptor-enriched population, potentially due to induced serum progesterone as a resistance mechanism.

Background

Androgen receptor (AR) signaling and incomplete inhibition of estrogen signaling may contribute to metastatic breast cancer (MBC) resistance to a nonsteroidal aromatase inhibitor (NSAI; letrozole or anastrozole). We assessed whether combined inhibition of androgen biosynthesis with abiraterone acetate plus prednisone and estradiol synthesis with exemestane (E) may be of clinical benefit to postmenopausal patients with NSAI-pretreated estrogen receptor-positive (ER+) MBC.

Patients and methods

Patients (N = 297) were stratified by the number of prior therapies for metastatic disease (0–1 versus 2) and by prior NSAI use (adjuvant versus metastatic), and randomized (1 : 1 : 1) to receive oral once daily 1000 mg abiraterone acetate plus 5 mg prednisone (AA) versus AA with 25 mg E (AAE) versus 25 mg E alone (E). Each treatment arm was well balanced with regard to the proportion of patients with AR-positive breast cancer. The primary end point was progression-free survival (PFS). Secondary end points included overall survival, clinical benefit rate, duration of response, and overall response rate.

Results

There was no significant difference in PFS with AA versus E (3.7 versus 3.7 months; hazard ratio [HR] = 1.1; 95% confidence interval [CI] 0.82–1.60; P = 0.437) or AAE versus E (4.5 versus 3.7 months; HR = 0.96; 95% CI 0.70–1.32; P = 0.794). Increased serum progesterone concentrations were observed in both arms receiving AA, but not with E. Grade 3 or 4 treatment-emergent adverse events associated with AA, including hypokalemia and hypertension, were less common in patients in the E (2.0% and 2.9%, respectively) and AA arms (3.4% and 1.1%, respectively) than in the AAE arm (5.8% for both).

Conclusions

Adding AA to E in NSAI-pretreated ER+ MBC patients did not improve PFS compared with treatment with E. An AA-induced progesterone increase may have contributed to this lack of clinical activity.

ClinicalTrials.gov

NCT01381874.

Alcohol Consumption and Risk of Breast Cancer by Tumor Receptor Expression

In epidemiologic studies, alcohol consumption appears more strongly associated with risk of estrogen receptor (ER)-positive than ER-negative breast cancer. However, this association has not been assessed by other potentially relevant tumor markers, such as androgen receptor (AR) or insulin receptor (IR). In the prospective Nurses' Health Study cohort, we evaluated alcohol consumption and breast cancer risk by individual tumor marker expression (i.e., ER, progesterone receptor [PR], AR, and IR) while controlling for other markers and also assessed the joint effect of these receptors. During 26 years follow-up of 106,037 women, 2552 invasive breast cancers contributed to the analysis. When all four markers were considered simultaneously, no significant heterogeneity of the alcohol and breast cancer association was observed by any of the markers. However, each increment in one drink per day was associated with 10% (95% confidence interval [CI] = 4%, 15%) and 9% (95% CI = 4%, 15%) increased risk of AR-positive and ER-positive breast cancer, respectively, while no increased risk was observed among AR-negative or ER-negative tumors. The association was independent of PR and IR expression. Assessment of the joint expression of hormone receptors revealed a significantly increased risk among AR+/ER+/PR+ (hazard ratio [HR] per drink/day = 1.11, 95% CI = 1.06, 1.17) but not in other subgroups (e.g. , AR-/ER-/PR-: HR = 0.99; 95% CI = 0.88, 1.12). Our data suggest that the alcohol and breast cancer association may be more pronounced among ER-positive and/or AR-positive breast tumors. However, our data do not support an important role of IR in the association.

Expression of ARs in triple negative breast cancer tumors: a potential prognostic factor?

Background/aim

In light of the controversial published literature, this study aims to examine the potential prognostic role of AR immunohistochemical expression in triple negative breast cancer (TNBC).

Patients and methods

Ninety patients with TNBC were included in this study; the associations between AR expression (Allred score), clinicopathological variables (stage, grade, histological subtype, tumor size, nodal status, age at diagnosis, Ki67 expression, and p53 expression), and overall survival were evaluated.

Results

AR expression was not associated with stage, grade, histological subtype, tumor size, nodal status, age at diagnosis, Ki67 expression, and p53 expression. AR immunopositivity was not associated with overall survival either at the univariate or at the multivariate Cox regression analysis (multivariate hazard ratio =0.66, 95% confidence interval: 0.26–1.70, P=0.393).

Conclusion

AR expression does not seem to play a prognostic role in TNBC.

Hormone receptors as a marker of poor survival in epithelial ovarian cancer

OBJECTIVE

Androgen receptor (AR), estrogen receptor α and β (ERα, ERβ), and progesterone receptor (PR) are potential therapeutic targets in epithelial ovarian cancer. In this study we evaluate the prognostic value of these hormone receptors in ovarian cancer patients.

METHODS

In a prospective multicenter randomized controlled phase II trial 196 ovarian cancer patients were randomized to carboplatin/docetaxel±celecoxib. Of 121 patients sufficient tumor tissue was available for hormone receptor analysis. Tissue micro-arrays were stained for AR, ERα, ERβ, and PR. Cluster analysis was performed to identify subgroups based on hormone receptor expression profile. Receptor expression was correlated to progression-free survival (PFS) and overall survival (OS) in uni- and multivariate analysis.

RESULTS

AR, ERα, ERβ, and PR were expressed in respectively 10%, 31%, 73%, and 19%. In patients with synchronous metastasis tissue available (n=69 patients), discordant receptor expression was observed in 9-32%. ERβ-expression was associated with poor PFS and OS (hazard ratios 1.88 and 1.92). Clustering analysis revealed a subgroup with hormone receptor negative disease that had a favorable PFS and OS.

CONCLUSION

Hormone receptors are expressed in the majority of ovarian cancer tumors and may serve as therapeutic targets. Clustering analysis can reveal subgroups with different outcome, which may prove valuable in selecting patients for endocrine therapy.

Androgen Receptor (AR), E-Cadherin, and Ki-67 as Emerging Targets and Novel Prognostic Markers in Triple-Negative Breast Cancer (TNBC) Patients

Background

TNBC is an aggressive subset of breast cancer (BC) without specific target therapy.

Methods

This observational, retrospective study included 45 cases of TNBC. The aim of this study was to evaluate the expression of the AR, E-cadherin and Ki-67 in relation to histological type, time to relapse and overall survival (OS). Immunohistochemistry (IHC) was carried out on formalin-fixed paraffin-embedded tumor samples obtained from patients defined TNBC.

Results

The AR was positive (IHC >10%) in 26.6%. E-cadherin (CDH1) expression was considered positive if the score was ≥ 2. This expression was negative in 53.3% cases. The Ki-67 index was ≥ 20% in 37.7%. Univariate analyses showed that AR, CDH1 and Ki-67 are significantly associated with OS. Multivariate analysis showed that AR and Ki-67 expression are independent variables associated with OS. The statistical analysis showed that patients with AR negative and Ki-67 positive expression have a significant correlation with poor outcome.

Conclusions

Our data suggest that the combination of AR and E-cadherin expression as well as Ki-67 status might be useful prognostic markers in TNBC. Hence, these molecular determinants could play an interesting role to classify subgroups of TNBC.

Influence of Androgen Receptor Expression on the Survival Outcomes in Breast Cancer: A Meta-Analysis

PURPOSE

Despite the fact that the androgen receptor (AR) is known to be involved in the pathogenesis of breast cancer, its prognostic effect remains controversial. In this meta-analysis, we explored AR expression and its impact on survival outcomes in breast cancer.

METHODS

We searched PubMed, EMBASE, Cochrane Library, ScienceDirect, SpringerLink, and Ovid databases and references of articles to identify studies reporting data until December 2013. Disease-free survival (DFS) and overall survival (OS) were analyzed by extracting the number of patients with recurrence and survival according to AR expression.

RESULTS

There were 16 articles that met the criteria for inclusion in our meta-analysis. DFS and OS were significantly longer in patients with AR expression compared with patients without AR expression (odds ratio [OR], 0.60; 95% confidence interval [CI], 0.40-0.90; OR, 0.53; 95% CI, 0.38-0.73, respectively). In addition, hormone receptor (HR) positive patients had a longer DFS when AR was also expressed (OR, 0.63; 95% CI, 0.41-0.98). For patients with triple negative breast cancer (TNBC), AR expression was also associated with longer DFS and OS (OR, 0.44, 95% CI, 0.26-0.75; OR, 0.26, 95% CI, 0.12-0.55, respectively). Furthermore, AR expression was associated with a longer DFS and OS in women (OR, 0.42, 95% CI, 0.27-0.64; OR, 0.47, 95% CI, 0.38-0.59, respectively). However, in men, AR expression was associated with a worse DFS (OR, 6.00; 95% CI, 1.46-24.73).

CONCLUSION

Expression of AR in breast cancer might be associated with better survival outcomes, especially in patients with HR-positive tumors and TNBC, and women. Based on this meta-analysis, we propose that AR expression might be related to prognostic features and contribute to clinical outcomes.

Targeting the androgen receptor in prostate and breast cancer: several new agents in development

Prostate cancer (PCa) and breast cancer (BCa) share similarities as hormone-sensitive cancers with a wide heterogeneity of both phenotype and biology. The androgen receptor (AR) is a hormone receptor involved in both benign and malignant processes. Targeting androgen synthesis and the AR pathway has been and remains central to PCa therapy. Recently, there has been increased interest in the role of the AR in BCa development and growth, with results indicating AR co-expression with estrogen, progesterone, and human epidermal growth factor receptors, across all intrinsic subtypes of BCa. Targeting the AR axis is an evolving field with novel therapies in development which may ultimately be applicable to both tumor types. In this review, we offer an overview of available agents which target the AR axis in both PCa and BCa and provide insights into the novel drugs in development for targeting this signaling pathway.

Is the future of personalized therapy in triple-negative breast cancer based on molecular subtype?

Significant research has been conducted to better understand the extensive, heterogeneous molecular features of triple-negative breast cancer (TNBC). We reviewed published TNBC molecular classifications to identify major groupings that have potential for clinical trial development. With the ultimate aim to streamline translational medicine, we linked these categories of TNBC according to their gene-expression signatures, biological function, and clinical outcome. To this end, we define five potential clinically actionable groupings of TNBC: 1) basal-like TNBC with DNA-repair deficiency or growth factor pathways; 2) mesenchymal-like TNBC with epithelial-to-mesenchymal transition and cancer stem cell features; 3) immune-associated TNBC; 4) luminal/apocrine TNBC with androgen-receptor overexpression; and 5) HER2-enriched TNBC. For each defined subtype, we highlight the major biological pathways and discuss potential targeted therapies in TNBC that might abrogate disease progression. However, many of these potential targets need clinical validation by clinical trials. We have yet to know how we can enrich the targets by molecular classifications.

Expression of androgen receptor and its association with estrogen receptor and androgen receptor downstream proteins in normal/benign breast luminal epithelium

The androgen receptor (AR) is strongly expressed in the majority of breast carcinomas, but its role in breast hormonal carcinogenesis is not clear. We believe a better knowledge of the biology of normal/benign breast tissue will be the key to understanding this process. Using standard immunohistochemical staining on consecutive sections and dual immunohistochemical labeling, we studied the expression pattern of AR and estrogen receptor (ER) in normal/benign breast luminal epithelial cells. We found that most of the AR-positive cells are also ER positive, about 10% of the cells are AR-positive only, whereas ER-positive only cells are uncommon, a distribution pattern of hormone receptor expression similar to what was revealed in invasive breast carcinomas. Whereas the expression of AR downstream proteins, such as prostate-specific antigen and gross cystic disease fluid protein, was either negative or unrelated to the AR status. We conclude that AR and ER expression status in invasive breast carcinomas reflects that of their progenitor cells in terminal duct lobular units. Our study did not reveal the expression of AR downstream proteins in normal/benign luminal epithelial cells at the regular immunohistochemistry level.

The fate of chemoresistance in triple negative breast cancer (TNBC)

BACKGROUND

Treatment options for women presenting with triple negative breast cancer (TNBC) are limited due to the lack of a therapeutic target and as a result, are managed with standard chemotherapy such as paclitaxel (Taxol®). Following chemotherapy, the ideal tumour response is apoptotic cell death. Post-chemotherapy, cells can maintain viability by undergoing viable cellular responses such as cellular senescence, generating secretomes which can directly enhance the malignant phenotype.

SCOPE OF REVIEW

How tumour cells retain viability in response to chemotherapeutic engagement is discussed. In addition we discuss the implications of this retained tumour cell viability in the context of the development of recurrent and metastatic TNBC disease. Current adjuvant and neo-adjuvant treatments available and the novel potential therapies that are being researched are also reviewed.

MAJOR CONCLUSIONS

Cellular senescence and cytoprotective autophagy are potential mechanisms of chemoresistance in TNBC. These two non-apoptotic outcomes in response to chemotherapy are inextricably linked and are neglected outcomes of investigation in the chemotherapeutic arena. Cellular fate assessments may therefore have the potential to predict TNBC patient outcome.

GENERAL SIGNIFICANCE

Focusing on the fact that cancer cells can bypass the desired cellular apoptotic response to chemotherapy through cellular senescence and cytoprotective autophagy will highlight the importance of targeting non-apoptotic survival pathways to enhance chemotherapeutic efficacy.

In-silico identification and functional validation of allele-dependent AR enhancers

Androgen Receptor (AR) and Estrogen Receptors (ERs) are key nuclear receptors that can cooperate in orchestrating gene expression programs in multiple tissues and diseases, targeting binding elements in promoters and distant enhancers. We report the unbiased identification of enhancer elements bound by AR and ER-α whose activity can be allele-specific depending on the status of nearby Single Nucleotide Polymorphisms (SNP). ENCODE data were computationally mined to nominate genomic loci with: (i) chromatin signature of enhancer activity from activation histone marks, (ii) binding evidence by AR and ER-α, (iii) presence of a SNP. Forty-one loci were identified and two, on 1q21.3 and 13q34, selected for characterization by gene reporter, Chromatin immunoprecipitation (ChIP) and RT-qPCR assays in breast (MCF7) and prostate (PC-3) cancer-derived cell lines. We observed allele-specific enhancer activity, responsiveness to ligand-bound AR, and potentially influence on the transcription of closely located genes (RAB20, ING1, ARHGEF7, ADAM15). The 1q21.3 variant, rs2242193, showed impact on AR binding in MCF7 cells that are heterozygous for the SNP. Our unbiased genome-wide search proved to be an efficient methodology to discover new functional polymorphic regulatory regions (PRR) potentially acting as risk modifiers in hormone-driven cancers and overall nominated SNPs in PRR across 136 transcription factors.

Androgen receptor, EGFR, and BRCA1 as biomarkers in triple-negative breast cancer: a meta-analysis

OBJECTIVE

More and more evidences demonstrate that androgen receptor (AR), epidermal growth factor receptor (EGFR), and breast cancer susceptibility gene 1 (BRCA1) have unique clinical implications for targeted therapy or prognosis in triple-negative breast cancer (TNBC). Therefore, we conducted a meta-analysis to summarize the possible associations.

METHODS

We retrieved published articles about AR, EGFR, and BRCA1 in TNBC from PubMed and EMBASE. The analysis was performed with Rev-Man 5.2 software.

RESULTS

A total of 38 articles were eligible for the meta-analysis. Our study showed that the expression level of EGFR (OR = 6.88, P < 0.00001) and the prevalence of BRCA1 mutation (RR = 5.26, P < 0.00001) were higher in TNBC than non-TNBC. In contrast, the expression level of AR was lower in TNBC than non-TNBC (OR = 0.07, P < 0.00001). In the subgroup related to EGFR expression, the level of EGFR expression was significantly increased in Asians (OR = 9.60) compared with Caucasians (OR = 5.53) for TNBC patients. Additionally, the prevalence of BRCA1 mutation in Asians (RR = 5.43, P < 0.00001) was higher than that in Caucasians (RR = 5.16, P < 0.00001).

CONCLUSIONS

The distinct expression of AR and EGFR and the prevalence of BRCA1 mutation indicated that AR, EGFR, and BRCA1 might be unique biomarkers for targeted therapy and prognosis in TNBC.

Prolactin-induced protein is required for cell cycle progression in breast cancer

Prolactin-induced protein (PIP) is expressed in the majority of breast cancers and is used for the diagnostic evaluation of this disease as a characteristic biomarker; however, the molecular mechanisms of PIP function in breast cancer have remained largely unknown. In this study, we carried out a comprehensive investigation of PIP function using PIP silencing in a broad group of breast cancer cell lines, analysis of expression microarray data, proteomic analysis using mass spectrometry, and biomarker studies on breast tumors. We demonstrated that PIP is required for the progression through G1 phase, mitosis, and cytokinesis in luminal A, luminal B, and molecular apocrine breast cancer cells. In addition, PIP expression is associated with a transcriptional signature enriched with cell cycle genes and regulates key genes in this process including cyclin D1, cyclin B1, BUB1, and forkhead box M1 (FOXM1). It is notable that defects in mitotic transition and cytokinesis following PIP silencing are accompanied by an increase in aneuploidy of breast cancer cells. Importantly, we have identified novel PIP-binding partners in breast cancer and shown that PIP binds to β-tubulin and is necessary for microtubule polymerization. Furthermore, PIP interacts with actin-binding proteins including Arp2/3 and is needed for inside-out activation of integrin-β1 mediated through talin. This study suggests that PIP is required for cell cycle progression in breast cancer and provides a rationale for exploring PIP inhibition as a therapeutic approach in breast cancer that can potentially target microtubule polymerization.

Triple-negative breast cancer: new perspectives for targeted therapies

Breast cancer is a heterogeneous disease, encompassing a large number of entities showing different morphological features and having clinical behaviors. It has became apparent that this diversity may be justified by distinct patterns of genetic, epigenetic, and transcriptomic aberrations. The identification of gene-expression microarray-based characteristics has led to the identification of at least five breast cancer subgroups: luminal A, luminal B, normal breast-like, human epidermal growth factor receptor 2, and basal-like. Triple-negative breast cancer is a complex disease diagnosed by immunohistochemistry, and it is characterized by malignant cells not expressing estrogen receptors or progesterone receptors at all, and human epidermal growth factor receptor 2. Along with this knowledge, recent data show that triple-negative breast cancer has specific molecular features that could be possible targets for new biological targeted drugs. The aim of this article is to explore the use of new drugs in this particular setting, which is still associated with poor prognosis and high risk of distant recurrence and death.

Prolactin-induced protein in breast cancer

Prolactin-induced protein (PIP) is a 17-kDa single polypeptide chain that is secreted by a number of normal apocrine cells, such as milk, saliva, and seminal fluid. PIP is widely expressed in breast cancer and is commonly used as a diagnostic biomarker for the histopathological diagnosis of this disease. Expression of PIP in breast cancer is regulated by androgen and prolactin through a number of transcription factors and signaling cross-talks, including STAT5, Runx2, and CREB1. Notably, PIP is induced by a positive feedback loop between androgen receptor (AR) and extracellular signal-regulated kinase (ERK). The available data indicate that PIP has an aspartyl protease activity that can degrade fibronectin. Importantly, PIP is necessary for outside-in activation of integrin-β1 signaling pathway and regulation of key downstream signaling targets of this pathway such as interaction of integrin-β1 with integrin-linked kinase 1 (ILK1) and ErbB2. Furthermore, the importance of PIP in cell proliferation has been demonstrated by the fact that purified PIP promotes growth of breast cancer cells and PIP expression is necessary for the proliferation of T-47D and MDA-MB-453 cell lines. In addition to cell proliferation, PIP mediates invasion of breast cancer cells in a process that partially depends on the degradation of fibronectin by this protein. Therefore, PIP is a breast cancer-related protein that is expressed in a majority of breast tumors and has a significant function in the biology of this disease.

Differences in biological features of breast cancer between Caucasian (Italian) and African (Tanzanian) populations

Information on hormone receptor and human epidermal growth factor receptor-2 (HER2) expression in breast cancer is acknowledged as mandatory for prognostic stratification and treatment planning. Data on the biological features of African breast cancers are poor. We decided to compare histopathological and biomolecular characteristics (estrogen and progesterone receptor—ER, PgR, and HER2) of Tanzanian and Italian breast cancers. Differences in proliferating index and androgen receptor (AR) expression in triple-negative patients from the two case series were also assessed. Of the 103 consecutive patients seen at the Bugando Medical Center (Mwanza, Tanzania) from 2003 to 2010, who underwent biopsy or surgical resection of primary breast cancer, 69 patients had tissue samples that were evaluable for estrogen receptor (ER), progesterone receptor (PgR), and HER2. Histopathological assessment and biomolecular determinations were performed at the Cancer Institute of Romagna (IRST IRCCS, Meldola, Italy). Caucasian breast cancers were randomly extracted from an electronic database and matched (1:2 ratio) for year of diagnosis and age at diagnosis. Median age of both populations was 51 years (range 27–84). With respect to Caucasian tumors, Tanzanian breast cancers at diagnosis more frequently showed high histological grade (mainly grade 3) (P = 0.03), advanced clinical stage (III or IV) (P\0.001), ER negativity (52.2 %, P\0.001) and high proliferation (P = 0.0002). Triple-negative tumors were over-represented in Tanzanian women. AR was positive in 38.5 and 38 %of triple-negative Tanzanian and Italian breast cancers, respectively. Our results show that histopathological and biomolecular characteristics in Tanzanian and Italian breast cancers differ substantially. The high frequency of poorly differentiated, ER-negative, highly proliferating tumors, together with advanced stage at presentation, could be considered as the main prognostic factors linked to the high mortality rates for breast cancer in the African population.

Dietary lignan intake and androgen receptor expression in breast tumors

PURPOSE

Lignans, a class of phytoestrogen commonly found in the Western diet, have been linked to decreased breast cancer risks in epidemiologic studies. Similar to estrogen receptors, the androgen receptor (AR), a prognostic factor in breast tumors, may be affected by lignans. However, few studies have investigated this link in the context of breast cancer etiology. We evaluated the relationship between dietary lignan intake and AR expression in incident breast tumors.

METHODS

Tumor tissue, epidemiological, and clinical data were collected from 216 women with incident, primary, histologically confirmed breast cancer enrolled in the Roswell Park Cancer Institute (RPCI) Data Bank and BioRepository (DBBR). On average, three tumor cores from each participant were assembled into a tissue micro array. After immunohistochemical staining, a trained RPCI pathologist determined AR status of each core. Lignan intake was calculated from a food frequency questionnaire collected upon enrollment into the DBBR.

RESULTS

We observed a weak positive association between dietary lignans and AR expression [β (SE) 27.6 (17.0), p 0.10], and there was no significant difference in lignan intake across categories of AR expression (p = 0.09, R (2) = 0.35).

CONCLUSION

Our results do not support a clear relationship between dietary lignan intake and AR expression. This investigation is the first, to our knowledge, to examine dietary lignan intake and AR expression in breast tumors. Further research is needed within a larger, more representative sample to determine whether lignan intake is truly associated with AR expression.

Periocular sebaceous gland carcinoma: do androgen receptor (NR3C4) and nuclear survivin (BIRC5) have a prognostic significance?

PURPOSE

The study aimed at evaluating the expression of androgen receptor (AR) and nuclear survivin (NS) in periocular sebaceous gland carcinoma (SGC) and to determine whether this expression is associated with histopathological features, markers of apoptosis and proliferation and with clinical outcomes.

METHODS

This was a retrospective, comparative case series which included 56 patients with a biopsy-proven periocular SGC. Immunohistochemical staining for AR, survivin, p53 and Ki-67 was analysed in all cases.

RESULTS

All patients expressed AR, p53 and Ki-67 in the nucleus of tumour cells. Twenty-four patients (42.8%) had a high AR score, and 32 patients (57.2%) had a low AR score. Twenty-four (42.8%) patients expressed survivin in the nucleus of tumour cells. Nine (37.5%) had a high NS score, and 15 (62.5%) had a low NS score. Patients with a high AR score had a greater recurrence (p < 0.005), higher expression of Ki-67 (p < 0.0001) and a lower p53 expression (p < 0.005). Nuclear expression of survivin correlated with a high Ki-67 labelling index (0.0001) and low p53 expression (<0.005). Neither nuclear expression of survivin nor the NS score correlated with any clinicopathological features.

CONCLUSION

Expression of AR significantly impacts prognosis and is thus promising prognostic marker in periocular SGC.

Selective androgen receptor modulators as improved androgen therapy for advanced breast cancer

Androgens were at one time a therapeutic mainstay in the treatment of advanced breast cancer. Despite comparable efficacy, SERMs and aromatase inhibitors eventually became the therapies of choice due to in part to preferred side-effect profiles. Molecular characterization of breast tumors has revealed an abundance of androgen receptor expression but the choice of an appropriate androgen receptor ligand (agonist or antagonist) has been confounded by multiple conflicting reports concerning the role of the receptor in the disease. Modern clinical efforts have almost exclusively utilized antagonists. However, the recent clinical development of selective androgen receptor modulators with greatly improved side-effect profiles has renewed interest in androgen agonist therapy for advanced breast cancer.

Clinicopathologic study of salivary duct carcinoma and the efficacy of androgen deprivation therapy

OBJECTIVE

Salivary duct carcinoma is a rare and aggressive tumor of the salivary glands. The objectives of this study were to investigate the clinicopathological features of salivary duct carcinoma and to determine whether androgen deprivation therapy should be recommended.

STUDY DESIGN AND METHODS

The clinical records of seven patients diagnosed with salivary duct carcinoma between 2002 and 2012 were retrospectively assessed. Tumor specimens were examined for overexpression of human epidermal growth factor receptor 2 (HER2) and androgen receptor by immunohistochemistry. A case of androgen receptor-positive salivary duct carcinoma who received androgen deprivation therapy is presented.

RESULTS

Of the seven patients, 43% had recurrences and metastases, and the 5-year survival rate was 68.6%. All patients were androgen receptor-positive, and 71% were HER2-positive. One patient, a 66-year-old man with androgen receptor-positive salivary duct carcinoma, received oral bicalutimide for 14 months and practically all lung metastases disappeared.

CONCLUSION

Androgen receptor is often overexpressed in salivary duct carcinoma. Androgen deprivation therapy is safe and should be considered for patients with androgen receptor-positive salivary duct carcinoma.

Claudin 4 expression in triple-negative breast cancer: correlation with androgen receptors and Ki-67 expression

Breast cancer is the most common malignancy in women and the leading cause of cancer mortality worldwide. Triple-negative breast cancer (TNBC) is an important phenotype of breast cancer that accounts for a relatively small number of breast cancer cases but still represent a focus of increasing interest at the clinical, biological, and epidemiological level. Claudins are the major component of the tight junction, and only a few studies have addressed the role of claudins in breast cancer, especially TNBC. Androgen receptors (ARs), as members of the nuclear receptor superfamily, are known to be involved in a complex network of signaling pathways that collectively regulate cell proliferation. However, roles of AR in breast cancer development and progression have not been very clearly understood. The proliferation marker Ki-67 has been confirmed as an independent predictive and prognostic factor in early breast cancer. The aims of this study are to identify the clinicopathologic associations and prognostic value of claudin 4 expression in TNBC and to correlate claudin 4 expression with AR status and Ki-67 expression. Paraffin blocks obtained from 56 female patients with triple-negative primary invasive ductal breast carcinomas were analyzed for claudin 4, AR, and Ki-67 immunohistochemical expression. High levels of claudin 4 expression were detected in 66.1% of TNBC cases. There was a significant positive correlation with age, tumor size, grade, nodal status, metastasis, and Ki-67 expression (all P < .05) and negative correlation with AR status (P < .001). Androgen receptor showed positivity in 29 cases (51.78%). There was a statistical negative correlation with the all the studied clinicopathologic parameters, claudin 4 and Ki-67 expression. High claudin 4 expression, negative AR expression, and high Ki-67 index would provide a strong prognostic power to differentiate the patients with worse outcome among TNBC patients. Moreover, target treatment for TNBC cells expressing claudin 4 or AR enriched would be valuable for future therapies.

Coagulation factor VII is regulated by androgen receptor in breast cancer

Androgen receptor (AR) is widely expressed in breast cancer; however, there is limited information on the key molecular functions and gene targets of AR in this disease. In this study, gene expression data from a cohort of 52 breast cancer cell lines was analyzed to identify a network of AR co-expressed genes. A total of 300 genes, which were significantly enriched for cell cycle and metabolic functions, showed absolute correlation coefficients (|CC|) of more than 0.5 with AR expression across the dataset. In this network, a subset of 35 "AR-signature" genes were highly co-expressed with AR (|CC|>0.6) that included transcriptional regulators PATZ1, NFATC4, and SPDEF. Furthermore, gene encoding coagulation factor VII (F7) demonstrated the closest expression pattern with AR (CC=0.716) in the dataset and factor VII protein expression was significantly associated to that of AR in a cohort of 209 breast tumors. Moreover, functional studies demonstrated that AR activation results in the induction of factor VII expression at both transcript and protein levels and AR directly binds to a proximal region of F7 promoter in breast cancer cells. Importantly, AR activation in breast cancer cells induced endogenous factor VII activity to convert factor X to Xa in conjunction with tissue factor. In summary, F7 is a novel AR target gene and AR activation regulates the ectopic expression and activity of factor VII in breast cancer cells. These findings have functional implications in the pathobiology of thromboembolic events and regulation of factor VII/tissue factor signaling in breast cancer.

A targetable androgen receptor-positive breast cancer subtype hidden among the triple-negative cancers

CONTEXT

Triple-negative breast cancer (TNBC) is a subgroup of breast cancers that by definition lack expression of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2). A diverse group of tumors, TNBC shares some morphologic and molecular features with basal-like breast cancer, a category of breast cancer defined by gene expression profiling. More likely to occur in young women and African Americans, TNBCs may exhibit aggressive behavior and are associated with poor prognosis despite their initial response to conventional chemotherapy. Because hormonal or HER2-targeted therapies are ineffective for these tumors, the main therapeutic option is systemic chemotherapy. Therefore, identification of new targets for therapy is urgently needed for this group.

OBJECTIVE

To review and present recent literature along with our own experience regarding the clinical and morphologic characteristics and the prevalence of androgen receptor (AR) expression in TNBC, and to discuss the potential use of AR as a therapeutic target for AR(+) TNBC.

DATA SOURCES

Data sources are published articles from peer-reviewed journals in PubMed (US National Library of Medicine).

CONCLUSIONS

AR is the most commonly expressed hormone receptor among all breast carcinomas, with a prevalence of 25% to 75% among TNBCs. Therefore, we strongly support the routine assessment of AR in TNBC, and preferably in all breast carcinomas.

Triple-negative breast cancer: investigating potential molecular therapeutic target

INTRODUCTION

Triple-negative breast cancer (TNBC) makes up about 10 - 20% of all breast cancers and the lack of hormone receptors and human epidermal growth factor receptor-2/Neu expression is responsible for poor prognosis, no targeted therapies and trouble in the clinical management. Tumor heterogeneity, also within the same tumor, is a major cause for this difficulty. Based on the introduction of new biological drugs against different kinds of tumor, many efforts have been made for classification of genetic alterations present in TNBC, leading to the identification of several oncogenes and tumor suppressor genes involved in breast cancer carcinogenesis.

AREAS COVERED

In this review we investigated the molecular alteration present in TNBC which could lead to the creation of new targeted therapies in the future, with the aim to counteract this disease in the most effective way.

EXPERT OPINION

In this context some hormone receptors like G-protein-coupled receptor 30 and androgen receptors may be a fascinating area to investigate; also, angiogenesis, represented not only by the classical VEGF/VEGFR relationship, but also by other molecules, like semaphorins, fibroblast growth factor and heparin-binding-EGF-like, is a mechanism in which new developments are expected. In this perspective, one technique that may show promise is the gene therapy; in particular the gene transfer could correct abnormal genetic function in cancer cells.

Heterogeneity of triple-negative breast cancer: mammographic, US, and MR imaging features according to androgen receptor expression

OBJECTIVE

Our aim was to determine whether triple-negative breast cancers (TNBCs) with and without androgen receptor (AR) expression have distinguishing imaging features on mammography, breast ultrasound (US), and magnetic resonance (MR) imaging.

METHODS

AR expression was assessed immunohistochemically in 125 patients with TNBC from a consecutive series of 1,086 operable invasive breast cancers. Two experienced radiologists blinded to clinicopathological findings reviewed all imaging studies in consensus using the BI-RADS lexicon. The imaging and pathological features of 33 AR-positive TNBCs were compared with those of 92 AR-negative TNBCs.

RESULTS

The presence of mammographic calcifications with or without a mass (p < 0.001), non-mass enhancement on MR imaging (p < 0.001), and masses with irregular shape or spiculated margins on US (p < 0.001 and p = 0.002) and MR imaging (p = 0.001 and p < 0.001) were significantly associated with AR-positive TNBC. Compared with AR-negative TNBC, AR-positive TNBC was more likely to have a ductal carcinoma in situ component (59.8% vs. 90.9%, p = 0.001) and low Ki-67 expression (30.4% vs. 51.5%, p = 0.030).

CONCLUSION

AR-positive and AR-negative TNBCs have different imaging features, and certain imaging findings can be useful to predict AR status in TNBC.

KEY POINTS

• Triple-negative breast cancers have distinguishing imaging features according to AR expression. • AR-positive TNBC is associated with calcifications, spiculated masses, and non-mass enhancement. • Multimodality imaging can help predict androgen receptor status in TNBC.

The renaissance of endocrine therapy in breast cancer

PURPOSE OF REVIEW

Endocrine therapy for breast cancer has been the cornerstone of treatment for over a century since the discovery of the regressive effect of oophorectomy on 'cancer of the mamma' in 1896 by Beatson. Studies in the prevention and treatment of both early and metastatic breast cancer will be reviewed with a focus on recent large randomized clinical trials that may be practice changing.

RECENT FINDINGS

Data from pivotal clinical trials that looked at the duration of adjuvant tamoxifen therapy in premenopausal women will be discussed. In addition, several recent clinical trials that address the optimal sequence of endocrine therapy and advances in the treatment of endocrine-resistant metastatic disease will be reviewed. New findings from molecular studies that demonstrate targets in the endocrine axis and the role of aromatase inhibitors in the prevention setting will be highlighted.

SUMMARY

Overall, these clinical trials show the benefit of aromatase inhibitors in the prevention setting, longer duration of tamoxifen in the adjuvant setting for premenopausal women, and new biologic agents with hormonal therapies.

Androgen receptor expression predicts decreased survival in early stage triple-negative breast cancer

BACKGROUND

A subset of triple-negative breast cancer (TNBC) has been reported to express androgen receptor (AR); however, the clinical significance of AR expression in TNBC is unclear.

METHODS

We examined immunohistochemical expression of AR in a large cohort of TNBC cases and correlated its expression with clinicopathologic features and clinical outcome.

RESULTS

AR expression was found in 17.7% (87/492) of TNBCs. Positive expression of AR showed significant correlation with older age (p < 0.001), apocrine histology (p = 0.001), and lower histologic grade (p < 0.001). AR was a poor prognostic marker for overall survival (OS) in univariate (p = 0.026) and multivariate (p = 0.008) analyses. In the lymph node-negative (n = 316) subgroup, AR expression was a significant predictor of worse OS and disease-free survival (DFS) in both univariate (p = 0.028 and 0.011) and multivariate (p = 0.024 and 0.01, respectively) analyses. AR expression also was a prognostic factor in pT1 subgroup (OS, p = 0.007; DFS, p = 0.01); however, its prognostic value was not observed in TNBC patients with lymph node metastasis or tumor size larger than pT1.

CONCLUSIONS

AR-expressing TNBCs represent a distinct breast cancer subgroup with adverse clinical outcome and AR blockade could be a potential endocrine therapy for these TNBC patients. Evaluation of AR status may provide additional information on prognosis and treatment in patients with TNBC.

Complexities of androgen receptor signalling in breast cancer

While the clinical benefit of androgen-based therapeutics in breast cancer has been known since the 1940s, we have only recently begun to fully understand the mechanisms of androgen action in breast cancer. Androgen signalling pathways can have either beneficial or deleterious effects in breast cancer depending on the breast cancer subtype and intracellular context. This review discusses our current knowledge of androgen signalling in breast cancer, including the relationship between serum androgens and breast cancer risk, the prognostic significance of androgen receptor (AR) expression in different breast cancer subtypes and the downstream molecular pathways mediating androgen action in breast cancer cells. Intracrine androgen metabolism has also been discussed and proposed as a potential mechanism that may explain some of the reported differences regarding dichotomous androgen actions in breast cancers. A better understanding of AR signalling in this disease is critical given the current resurgence in interest in utilising contemporary AR-directed therapies for breast cancer and the need for biomarkers that will accurately predict clinical response.

Influence of stromal-epithelial interactions on androgen action

Androgen receptor (AR) signaling is vital to the development and function of the prostate and is a key pathway in prostate cancer. AR is differentially expressed in the stroma and epithelium, with both paracrine and autocrine control throughout the prostate. Stromal-epithelial interactions within the prostate are commonly dependent on AR signaling and expression. Alterations in these pathways can promote tumorigenesis. AR is also expressed in normal and malignant mammary tissues. Emerging data indicate a role for AR in certain subtypes of breast cancer that has the potential to be exploited therapeutically. The aim of this review is to highlight the importance of these interactions in normal development and tumorigenesis, with a focus on the prostate and breast.

Androgen receptor expression in early triple-negative breast cancer: clinical significance and prognostic associations

BACKGROUND

Triple-negative breast cancers (TNBC) are characterized by aggressive tumour biology resulting in a poor prognosis. Androgen receptor (AR) is one of newly emerging biomarker in TNBC. In recent years, ARs have been demonstrated to play an important role in the genesis and in the development of breast cancer, although their prognostic role is still debated. In the present study, we explored the correlation of AR expression with clinical, pathological and molecular features and its impact on prognosis in early TNBC.

PATIENTS AND METHODS

ARs were considered positive in case of tumors with >10% nuclear-stained. Survival distribution was estimated by the Kaplan Meier method. The univariate and multivariate analyses were performed. The difference among variables were calculated by chi-square test.

RESULTS

81 TNBC patients diagnosed between January 2006 and December 2011 were included in the analysis. Slides were stained immunohistochemically for estrogen and progesterone receptors, HER-2, Ki-67, ALDH1, e-cadherin and AR. Of the 81 TNBC samples, 18.8% showed positive immunostaining for AR, 23.5% and 44.4% of patients were negative for e-cadherin and ALDH1, respectively. Positive AR immunostaining was inversely correlated with a higher Ki-67 (p < 0.0001) and a lympho-vascular invasion (p = 0.01), but no other variables. Univariate survival analysis revealed that AR expression was not associated with disease-free survival (p = 0.72) or overall survival (p = 0.93).

CONCLUSIONS

The expression of AR is associated with some biological features of TNBC, such as Ki-67 and lympho-vascular invasion; nevertheless the prognostic significance of AR was not documented in our analysis. However, since ARs are expressed in a significant number of TNBC, prospective studies in order to determine the biological mechanisms and their potential role as novel treatment target.

Expression of androgen receptor in inflammatory breast cancer and its clinical relevance

BACKGROUND

Inflammatory breast cancer (IBC) is characterized by an aggressive clinical course with early metastasis and frequent resistance to conventional therapies. Identifying a novel therapeutic approach may improve the prognosis for patients with IBC. Because androgen receptor (AR)-expressing tumors may be targeted by anti-AR therapy, the authors examined the prevalence of AR expression in IBC tumors and explored its clinical relevance.

METHODS

Tissue microarrays of 88 IBC tumors were stained immunohistochemically with monoclonal antibody against AR, and the results were correlated with clinicopathologic parameters and survival outcomes.

RESULTS

The median follow-up was 10.8 years. AR was positive in 39% of the IBC tumors and in approximately one-third of estrogen receptor (ER)-negative and progesterone receptor (PR)-negative tumors. AR positivity was significantly associated with lymphovascular invasion (P = .01) but not with other clinicopathologic parameters. There was a trend toward an association between AR expression and PR expression (P = .07). In univariate survival analysis, patients who had AR-negative/ER-negative tumors had significantly worse overall survival (P = .03) and disease-specific survival (P = .04) than patients who had tumors with other combinations of AR/ER status.

CONCLUSIONS

AR expression was common in IBC tumors, and AR positivity was significantly associated with lymphovascular invasion. Patients who had AR-negative/ER-negative tumors had the worst survival outcomes. Further study with a larger series will be required to delineate the biologic mechanisms of AR and their clinical significance in IBC tumors.

Revising the role of the androgen receptor in breast cancer

Breast cancer (BC) is traditionally viewed as an oestrogen-dependent disease in which the androgen receptor (AR) is inhibitory, counteracting the oncogenic activity of oestrogen receptor α (ERα (ESR1)). Most probably as a result of this crosstalk, the AR has prognostic value in ER-positive disease, with AR positivity reported to correlate with a better prognosis. Activation of the AR pathway has been previously used as a therapeutic strategy to treat BC, but its usage declined following the introduction of the anti-oestrogen tamoxifen. More recently, it has been demonstrated that a subset of triple-negative BCs (molecular apocrine) are dependent upon androgen signalling for growth and therapies that inhibit androgen signalling, currently used for the treatment of prostate cancer, e.g. the antiandrogen bicalutamide and the CYP17 inhibitor abiraterone acetate are undergoing clinical trials to investigate their efficacy in this BC subtype. This review summarises the current knowledge of AR activity in BC.

Age at first childbirth and oral contraceptive use are associated with risk of androgen receptor-negative breast cancer: the Malmö Diet and Cancer Cohort

PURPOSE

Risk factors for breast cancer vary according to breast cancer subtype. This study analyzes the impact of potential risk factors in breast cancer by androgen receptor (AR) status.

METHODS

A total of 17,035 women were followed in the population-based prospective Malmö Diet and Cancer Study. Baseline data included lifestyle factors including anthropometry, reproductive history, and exogenous hormone use. During follow-up (mean: 12.8 years), 747 invasive breast cancers were diagnosed. Expression of AR was determined by immunohistochemistry in tumor tissue microarrays.

RESULTS

AR status was assessable in 516 of 747 tumors (69%). Among these, 467 tumors (90.5%) were AR positive (AR(+)) and 49 tumors (9.5%) were AR negative (AR(-)). AR negativity was significantly associated with estrogen receptor (ER) and progesterone receptor negativity, higher grade and proliferation (Ki67). Cox regression analyses stratified by AR status showed significant associations between reproductive factors and AR(-) breast cancer. The older the woman at first childbirth the higher the risk of AR(-) breast cancer; adjusted HR≤20yrs = 0.35, HR>20-≤25yrs = 0.62, HRnulliparous = 1.00, HR>25-≤30yrs = 1.29, HR>30yrs = 1.92, p trend = 0.001. No such association was seen for AR(+) tumors. Similarly, ever oral contraceptive use increased the risk of AR(-) breast cancer [Adj. HR = 2.59, 95% CI (1.26-5.34)] compared to never use, but not for AR(+) breast cancer.

CONCLUSIONS

Advanced age at first child birth and use of oral contraceptives were associated with increased risk of AR(-) breast cancer. This study may contribute to enhanced understanding of the role of the AR in breast carcinogenesis and improve risk stratification tools for personalized breast cancer prevention.

Expression of the Androgen Receptor, pAkt, and pPTEN in Breast Cancer and Their Potential in Prognostication

BACKGROUND

Importance of androgen receptor (AR) as an independent prognostic marker in Pakistani women with breast cancer (BCa) remains unexplored. Our aim was to identify the expression and potential prognostic value of AR, its upstream regulator (pAkt) and target gene (pPTEN) in invasive BCa.

METHODS

This study used a cohort of 200 Pakistani women with invasive BCa diagnosed during 2002-2011. Expression of AR, pAkt and pPTEN was determined on formalin fixed paraffin embedded tissue sections by immunohistochemistry. The association of AR, pAkt and pPTEN with clinicopathological parameters was determined. Survival analyses were undertaken on patients with ≥5years of follow-up (n=82).

RESULTS

Expression of AR, pAkt and pPTEN was observed in 47.5%, 81.3% and 50.6% of patients, respectively. AR-expressing tumors were low or intermediate in grade (P<.001) and expressed ER (P=.002) and PR (P=.001). Patients with AR+ tumors had significantly higher OS (Mean OS=10.2±0.465years) compared to patients with AR- tumors (Mean OS=5.8±0.348years) (P=.047). Furthermore, AR-positivity was associated with improved OS in patients receiving endocrine therapy (P=.020). Patients with AR+ /pAkt+ /pPTEN- tumors, had increased OS (Mean OS=7.1±0.535years) compared to patients with AR-/pAkt+/pPTEN- tumors (Mean OS=5.1±0.738years).

CONCLUSION

AR-expressing tumors are frequently characterized by low or intermediate grade tumors, expressing ER and PR. In addition, expression of AR, pAkt and pPTEN, could be considered in prognostication of patients with invasive BCa.

Phospho-kinase profile of triple negative breast cancer and androgen receptor signaling

Background

The androgen receptor (AR) plays a central role in the oncogenesis of different tumors, as is the case in prostate cancer. In triple negative breast cancer (TNBC) a gene expression classification has described different subgroups including a luminal androgen subtype. The AR can be controlled by several mechanisms like the activation of membrane tyrosine kinases and downstream signaling pathways. However little is known in TNBC about how the AR is modulated by these mechanisms and the potential therapeutic strategists to inhibit its expression.

Methods

We used human samples to evaluate the expression of AR by western-blot and phospho-proteomic kinase arrays that recognize membrane tyrosine kinase receptors and downstream mediators. Western-blots in human cell lines were carried out to analyze the expression and activation of individual proteins. Drugs against these kinases in different conditions were used to measure the expression of the androgen receptor. PCR experiments were performed to assess changes in the AR gene after therapeutic modulation of these pathways.

Results

AR is present in a subset of TNBC and its expression correlates with activated membrane receptor kinases-EGFR and PDGFRβ in human samples and cell lines. Inhibition of the PI3K/mTOR pathway in TNBC cell lines decreased notably the expression of the AR. Concomitant administration of the anti-androgen bicalutamide with the EGFR, PDGFRβ and Erk1/2 inhibitors, decreased the amount of AR compared to each agent given alone, and had an additive anti-proliferative effect. Administration of dihydrotestosterone augmented the expression of AR that was not modified by the inhibition of the PI3K/mTOR or Erk1/2 pathways. AR expression was posttranscriptionally regulated by PI3K or Erk1/2 inhibition.

Conclusion

Our results describe the expression of the AR in TNBC as a druggable target and further suggest the combination of bicalutamide with inhibitors of EGFR, PDGFRβ or Erk1/2 for future development.

The androgen receptor as a surrogate marker for molecular apocrine breast cancer subtyping

The Androgen Receptor (AR) is a potential prognostic marker and therapeutic target in breast cancer. We evaluated AR protein expression in high-risk breast cancer treated in the adjuvant setting. Tumors were subtyped into luminal (ER+/PgR±/AR±), molecular apocrine (MAC, [ER-/PgR-/AR+]) and hormone receptor negative carcinomas (HR-negative, [ER-/PgR-/AR-]). Subtyping was evaluated with respect to prognosis and to taxane therapy. High histologic grade (p < 0.001) and increased proliferation (p = 0.001) more often appeared in MAC and HR-negative than in luminal tumors. Patients with MAC had outcome comparable to the luminal group, while patients with HR-negative disease had increased risk for relapse and death. MAC outcome was favorable upon taxane-containing treatment; this remained significant upon multivariate analysis for overall survival (HR 0.31, 95%CI 0.13-0.74, interaction p = 0.035) and as a trend for time to relapse (p = 0.15). In conclusion, AR-related subtyping of breast cancer may be prognostic and serve for selecting optimal treatment combinations.

Loss of androgen receptor expression predicts early recurrence in triple-negative and basal-like breast cancer

Treatment of triple-negative invasive breast cancers, defined by the absence of estrogen and progesterone receptors and c-erbB2 expression, remains challenging. Androgen receptor, a member of the nuclear receptor superfamily that is involved in signaling pathways regulating cell proliferation, has been implicated in breast tumorigenesis. We immunohistochemically examined the expression of androgen receptor, basal markers (CK14, 34βE12) and EGFR in 699 triple-negative invasive breast cancers in tissue microarrays using the streptavidin-biotin method, and correlated the findings with clinical outcome. Positive androgen receptor expression was defined as staining of 1% or more of tumor cell nuclei. Survival outcomes were estimated with the Kaplan-Meier method and compared between groups with log-rank statistics. Cox proportional hazards models were used to determine the effect of androgen receptor on survival outcomes. Immunohistochemical positivity was observed in 38% of tumors, with the proportion of stained tumor cells ranging from 1 to 95% (mean 29%, median 10%). Androgen receptor expression was inversely associated with histologic grade and mitotic score. CK14, 34βE12 and EGFR confirmed 85% of cases to be basal-like, without significant association of basal-like phenotype with androgen receptor expression. Disease-free survival was significantly better in androgen receptor-positive triple-negative breast cancer, with a trend for improved overall survival. Decreased recurrence likelihood in both triple-negative and basal-like tumors (hazard ratio, 0.704; 95% confidence intervals, 0.498-0.994; P=0.0464; and hazard ratio, 0.675; 95% confidence intervals, 0.468-0.974; P=0.0355, respectively) was noted within 5 years of diagnosis but not thereafter. Our study suggests that loss of androgen receptor in triple-negative breast cancers augurs a worse prognosis, including those with basal-like features. More work in elucidating its relationship with mechanisms of progression, as well as trials of targeted treatment for androgen receptor-expressing triple-negative tumors, needs to be performed.

Subtype classification for prediction of prognosis of breast cancer from a biomarker panel: correlations and indications

Background

Hormone receptors, including the estrogen receptor and progesterone receptor, human epidermal growth factor receptor 2 (HER2), and other biomarkers like Ki67, epidermal growth factor receptor (EGFR, also known as HER1), the androgen receptor, and p53, are key molecules in breast cancer. This study evaluated the relationship between HER2 and hormone receptors and explored the additional prognostic value of Ki67, EGFR, the androgen receptor, and p53.

Methods

Quantitative determination of HER2 and EGFR was performed in 240 invasive breast cancer tissue microarray specimens using quantum dot (QD)-based nanotechnology. We identified two subtypes of HER2, ie, high total HER2 load (HTH2) and low total HER2 load (LTH2), and three subtypes of hormone receptor, ie, high hormone receptor (HHR), low hormone receptor (LHR), and no hormone receptor (NHR). Therefore, breast cancer patients could be divided into five subtypes according to HER2 and hormone receptor status. Ki67, p53, and the androgen receptor were determined by traditional immunohistochemistry techniques. The relationship between hormone receptors and HER2 was investigated and the additional value of Ki67, EGFR, the androgen receptor, and p53 for prediction of 5-year disease-free survival was assessed.

Results

In all patients, quantitative determination showed a statistically significant (P<0.001) negative correlation between HER2 and the hormone receptors and a significant positive correlation (P<0.001) between the estrogen receptor and the progesterone receptor (r=0.588), but a significant negative correlation (P<0.001, r=−0.618) with the HHR subtype. There were significant differences between the estrogen receptor, progesterone receptor, and HER2 subtypes with regard to total HER2 load and hormone receptor subtypes. The rates of androgen receptor and p53 positivity were 46.3% and 57.0%, respectively. Other than the androgen receptor, differences in expression of Ki67, EGFR, and p53 did not achieve statistical significance (P>0.05) between the five subtypes. EGFR and Ki67 had prognostic significance for 5-year disease-free survival in univariate analysis, but the androgen receptor and p53 did not. Multivariate analysis identified that EGFR expression had predictive significance for 5-year disease-free survival in hormone-receptor positive patients and in those with the lymph node-positive breast cancer subtype.

Conclusion

Hormone receptor expression was indeed one of the molecular profiles in the subtypes identified by quantitative HER2 and vice versa. EGFR status may provide discriminative prognostic information in addition to HER2 and hormone receptor status, and should be integrated into routine practice to help formulate more specific prediction of the prognosis and appropriate individualized treatment.