Prognostic relevance of androgen receptor detection in operable breast cancer

Androgen Receptor is Expressed in Breast Cancer Brain Metastases

BACKGROUND

Androgen receptor (AR) expression is a potential therapeutic target in breast cancer (BC) as it is frequently expressed in the luminal A and B subtypes and in approximately one third of basal-like cancers. As AR-positive BC displays a distinct biological behavior, we aimed to analyze AR expression in the particular context of BC brain metastases (BM).

MATERIALS AND METHODS

Patients with newly diagnosed BC BM treated with neurosurgical resection were identified from the Vienna Brain Metastasis Registry and clinical data including patient characteristics, biological tumor subtypes and overall survival were obtained by retrospective chart review. Formalin-fixed and paraffin-embedded specimen containing BM tissue were retrieved from the Neuro-Biobank. Immunohistochemical staining of AR was performed and AR expression in the tumor-cell nucleus was evaluated.

RESULTS

Fifty-seven BM samples from 57 individual patients with BC were available for this analysis. AR expression of ≥1% tumor cells was evident in 20/57 (35.1%) BM specimens; the median AR-expression rate was 10% (range: 1% to 60%). AR expression was observed in 11/21 (52.4%) BM of the luminal/human epidermal growth factor receptor 2 (HER2)-negative subtype, 3/13 (23.1%) of the luminal/HER2-positive subtype, 2/7 (28.6%) of the HER2-positive subtype and 4/16 (25.0%) of the triple-negative subtype (P=0.247). Median survival from diagnosis of BM was 10 months (range: 0 to 104 mo) in the entire cohort. No significant association of overall survival and AR expression ≥1% was observed (15 vs. 13 mo; P>0.05).

CONCLUSION

AR is expressed in more than one third of BC BM with the highest rates among the luminal/HER2-negative BC subtype and may therefore be a potential prognostic and predictive biomarker in this particular BC population.

The importance of androgen receptors in breast cancer

Background and aim

Breast cancer (BC) is the most common malignancy among women worldwide, and one of the leading causes of cancer-related deaths in females. For the breast malignant tumors there are numerous targeted therapies, depending on the receptors expressed. Regulating the process of epithelial-mesenchyme transcription, the steroid nuclear receptors are important in invasion and progression of BC cells. Till now, it is known that androgen receptor (AR) is present in about 60-80% of BC cells but, unfortunately, there is no targeted therapy available yet.

Methods

We revised the recent literature that included the AR mechanism of action in patients diagnosed with breast cancer, the preclinical, retrospective and clinical studies and the aspects related to the prognosis of these patients, depending on the molecular subtype.

Results

A total of 12 articles were eligible for this review. AR positivity was assessed using immunohistochemistry. Herein, neither 1 nor 10% cut-points were robustly prognostic. AR was an independent prognostic marker of BC outcome, especially in triple negative BC group.

Conclusion

AR is a potential targeted pathway which can improve the prognostic of AR positive patients with BC. Further preclinical and clinical studies are necessary to clarify the mechanism of action and to establish the drugs which can be used, either alone or in combination.

Immunohistochemical Expression of Androgen Receptors (AR) in Various Breast Cancer Subtypes

BACKGROUND:

Breast carcinoma ranks the first among malignant tumours in females and is the chief cause of cancer-related mortality. Androgen in implicated in the induction of proliferation and growth of mammary cells through binding to their corresponding receptors. Androgens influence the risk of acquiring breast cancer through either direct binding to androgen receptors (AR) or indirectly through their transformation to estradiol or competing for steroid binding proteins.

AIM:

To study the expression of AR in various breast cancer subtypes and to elucidate its clinical significance by correlating it with clinicopathological parameters.

METHODS:

One hundred and fifty breast cancer cases were studied using AR immunohistochemistry, and its expression was correlated with different clinicopathologic parameters and with ER, PR, Her-2/neu and Ki 67 expression.

RESULTS:

AR was expressed in 91 breast carcinoma cases out of 150 examined. There was a statistically significant correlation between AR expression and tumour size, mitotic count, tumour necrosis, infiltrative borders, the hormonal status of the tumour and subsequently luminal subtypes (p < 0.05). A subset of studied TNBC (34.6%) also expressed AR. On the other hand, there was no significant correlation between AR expression and other clinicopathological parameters.

CONCLUSION:

Positive AR immunostaining was associated with favourable prognostic factors and luminal subtypes (A&B). Also, a subset of TNBC cases showed positive AR expression. These results introduce the current potent, next-generation AR- antagonist as possible target therapy in breast cancer. Further researches on AR expression in breast cancer are recommended on a larger scale with follow up and survival to validate the current results.

The Magnitude of Androgen Receptor Positivity in Breast Cancer Is Critical for Reliable Prediction of Disease Outcome

Purpose: Consensus is lacking regarding the androgen receptor (AR) as a prognostic marker in breast cancer. The objectives of this study were to comprehensively review the literature on AR prognostication and determine optimal criteria for AR as an independent predictor of breast cancer survival.Experimental Design: AR positivity was assessed by immunostaining in two clinically validated primary breast cancer cohorts [training cohort, n = 219; validation cohort, n = 418; 77% and 79% estrogen receptor alpha (ERα) positive, respectively]. The optimal AR cut-point was determined by ROC analysis in the training cohort and applied to both cohorts.Results: AR was an independent prognostic marker of breast cancer outcome in 22 of 46 (48%) previous studies that performed multivariate analyses. Most studies used cut-points of 1% or 10% nuclear positivity. Herein, neither 1% nor 10% cut-points were robustly prognostic. ROC analysis revealed that a higher AR cut-point (78% positivity) provided optimal sensitivity and specificity to predict breast cancer survival in the training (HR, 0.41; P = 0.015) and validation (HR, 0.50; P = 0.014) cohorts. Tenfold cross-validation confirmed the robustness of this AR cut-point. Patients with ERα-positive tumors and AR positivity ≥78% had the best survival in both cohorts (P < 0.0001). Among the combined ERα-positive cases, those with comparable or higher levels of AR (AR:ERα-positivity ratio >0.87) had the best outcomes (P < 0.0001).Conclusions: This study defines an optimal AR cut-point to reliably predict breast cancer survival. Testing this cut-point in prospective cohorts is warranted for implementation of AR as a prognostic factor in the clinical management of breast cancer. Clin Cancer Res; 24(10); 2328-41. ©2018 AACR.

The Prognostic Role of Androgen Receptor in Patients with Early-Stage Breast Cancer: A Meta-analysis of Clinical and Gene Expression Data

Purpose: Androgen receptor (AR) expression has been observed in about 70% of patients with breast cancer, but its prognostic role remains uncertain.Experimental Design: To assess the prognostic role of AR expression in early-stage breast cancer, we performed a meta-analysis of studies that evaluated the impact of AR at the protein and gene expression level on disease-free survival (DFS) and/or overall survival (OS). Eligible studies were identified by systematic review of electronic databases using the MeSH-terms "breast neoplasm" and "androgen receptor" and were selected after a qualitative assessment based on the REMARK criteria. A pooled gene expression analysis of 35 publicly available microarray data sets was also performed from patients with early-stage breast cancer with available gene expression and clinical outcome data.Results: Twenty-two of 33 eligible studies for the clinical meta-analysis, including 10,004 patients, were considered as evaluable for the current study after the qualitative assessment. AR positivity defined by IHC was associated with improved DFS in all patients with breast cancer [multivariate (M) analysis, HR 0.46; 95% confidence interval (CI) 0.37-0.58, P < 0.001] and better OS [M-HR 0.53; 95% CI, 0.38-0.73, P < 0.001]. Thirty-five datasets including 7,220 patients were eligible for the pooled gene expression analysis. High AR mRNA levels were found to confer positive prognosis overall in terms of DFS (HR 0.82; 95% CI 0.72-0.92;P = 0.0007) and OS (HR 0.84; 95% CI, 0.75-0.94; P = 0.02) only in univariate analysis.Conclusions: Our analysis, conducted among more than 17,000 women with early-stage breast cancer included in clinical and gene expression analysis, demonstrates that AR positivity is associated with favorable clinical outcome. Clin Cancer Res; 23(11); 2702-12. ©2016 AACR.

Nuclear tristetraprolin acts as a corepressor of multiple steroid nuclear receptors in breast cancer cells

Tristetraprolin (TTP) is a 34-kDa, zinc finger-containing factor that in mammalian cells acts as a tumor suppressor protein through two different mechanisms. In the cytoplasm TTP promotes the decay of hundreds of mRNAs encoding cell factors involved in inflammation, tissue invasion, and metastasis. In the cell nucleus TTP has been identified as a transcriptional corepressor of the estrogen receptor alpha (ERα), which has been associated to the development and progression of the majority of breast cancer tumors. In this work we report that nuclear TTP modulates the transactivation activity of progesterone receptor (PR), glucocorticoid receptor (GR) and androgen receptor (AR). In recent years these steroid nuclear receptors have been shown to be of clinical and therapeutical relevance in breast cancer. The functional association between TTP and steroid nuclear receptors is supported by the finding that TTP physically interacts with ERα, PR, GR and AR in vivo. We also show that TTP overexpression attenuates the transactivation of all the steroid nuclear receptors tested. In contrast, siRNA-mediated reduction of endogenous TTP expression in MCF-7 cells produced an increase in the transcriptional activities of ERα, PR, GR and AR. Taken together, these results suggest that the function of nuclear TTP in breast cancer cells is to act as a corepressor of ERα, PR, GR and AR. We propose that the reduction of TTP expression observed in different types of breast cancer tumors may contribute to the development of this disease by producing a dysregulation of the transactivation activity of multiple steroid nuclear receptors.

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.

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.

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.

The impact of androgen receptor expression on breast cancer survival: a retrospective study and meta-analysis

Recent studies have highlighted the role of androgen receptor (AR) as a prognostic biomarker of breast cancer. However, its predictive role in disease free survival (DFS) and overall survival (OS) still remains inconclusive. The present study aimed to retrospectively investigate the association between AR and survival outcomes in breast cancer and also identify this association by a meta-analysis of published researches. Clinical data from 109 patients with breast cancer, who underwent surgery at Ruijin Hospital, Shanghai, were retrospectively analyzed for immunohistochemical AR expression measured by tissue microarray. For meta-analysis, articles available in Pubmed on the relationship between AR and breast cancer outcomes were included. Data obtained from both were combined and analyzed. Women with AR positive tumors in the retrospective study had a significantly better DFS (HR 0.24, 95% CI 0.07-0.88) and OS (HR 0.19, 95% CI 0.04-0.85) than women with AR negative ones. Meta-analysis showed that AR expression in breast tumors was an indicator of better DFS (HR 0.52, 95% CI 0.43-0.64). In subgroup analysis, AR could predict DFS outcome in estrogen receptor (ER) positive (HR 0.45, 95% CI 0.34-0.59), ER negative (HR 0.42, 95% CI 0.26-0.67), and triple negative breast cancer (HR 0.40, 95% CI 0.23-0.69). Moreover, in ER positive breast cancer patients, the expression of AR could predict better OS (HR 0.39, 95% CI 0.19-0.82). The present analysis indicated that AR expression was associated with lower risk of recurrence in patients with all breast cancer types and better OS in cases with ER positive.

The Role of the Androgen Receptor in Triple-Negative Breast Cancer

Greater than 70% of human breast cancers express the androgen receptor (AR). Emerging preclinical and clinical data suggest that AR may play a role in breast cancer pathogenesis and may serve as a therapeutic target in certain more difficult-to-treat breast cancer subtypes, such as triple-negative breast cancer. Although this is an area of active investigation, the clinical significance of this hormone receptor as a prognostic/predictive marker and its functional role in tumorigenesis is unclear. This review provides an update on the advances made in the last several years regarding the role of AR as a prognostic/predictive biomarker in breast cancer, the underlying biology of AR signaling in breast cancer development and the available clinical data for the use of androgen inhibition in the treatment of AR+ triple-negative breast cancer.

Androgen receptor in triple negative breast cancer

The clinical management of triple negative breast cancer (TNBC) is challenging due to the relatively aggressive biological behaviour and paucity of specific targeted therapy. A subset of TNBC patients has been reported to express androgen receptor (AR) in carcinoma cells and the manipulation of androgen signalling or AR targeted therapies have been proposed. However, the biological significance of AR in TNBC has remained relatively unknown. Therefore, this review aims to summarise the reported studies assessing the rates of AR positivity in TNBC patients and androgenic effects in TNBC cell lines. The rates of AR positivity among TNBC cases varied depending on the study population (0-53% of all TNBC patients). This difference among the reported studies may be largely due to the methodological differences of analysing AR. While the majority of cell line studies suggest that androgen increase proliferation and preliminary clinical studies suggest that AR antagonists improve the prognosis of AR positive TNBC patients, cell line transfection experiments and survival analyses of histological samples suggest that the presence of AR in tumour is either benign or predicts better survival. Therefore further translational investigations regarding the mechanisms of androgen action in TNBC are required to explain this discrepancy between clinical and basic studies.

The Role of Androgen Receptor in Breast Cancer

The androgen receptor (AR) is a proven clinical target in prostate cancer. Recent research indicates that it is an emerging hormonal target in breast cancer as well, with potential clinical benefit in both estrogen receptor(ER) positive and negative tumors. Compared to the ER, AR contains unique functional domains with relevance to its altered role in human breast cancer. The majority of ER-positive tumors express AR, and a significant percentage of ER-negative tumors might benefit from combined targeting of AR and the ErbB2/HER2 oncogene. Signaling downstream of AR might also affect many clinically important pathways which are also emerging clinical targets in breast cancer. AR expression might also play a role during tumor progression to metastatic disease. The role of AR as a new important biomarker in breast cancer will be reviewed herein.

Clinical importance of androgen receptor in breast cancer patients treated with adjuvant tamoxifen monotherapy

BACKGROUND: Despite many studies, the clinicopathological importance of the androgen receptor (AR) in breast cancer is not well established, and its significance as an independent predictor of clinical outcome is controversial. A large and systematic study is needed to address these issues. The aim of the present study was to elucidate whether AR has independent clinical value, examining its importance in a large and well-predefined patient group with a long follow-up period and complete clinicopathological data. METHODS: Archival materials of 403 invasive breast cancers from women treated with adjuvant tamoxifen monotherapy (median follow-up period 11.0 years) were subjected to immunohistochemical study using anti-AR monoclonal antibody. AR expression was compared with established clinicopathological factors, estrogen receptor (ER)-β expression, and clinical outcome. RESULTS: AR positivity was correlated with ER-α positivity, progesterone receptor positivity, ER-β positivity, and a lower nuclear grade. Patients with AR-positive carcinomas exhibited a significantly better clinical outcome than those with AR-negative carcinomas (P = 0.0165 for disease-free survival, P = 0.0344 for overall survival). Multivariate analysis did not yield significant differences in clinical outcome according to the AR status, whereas the ER-β status showed significant differences in multivariate analysis. CONCLUSIONS: Although, and in agreement with previous reports, AR positivity correlated with some established favorable prognostic factors and with ER-β positivity, AR was not an independent predictor of clinical outcome. Controversy regarding the value of AR as an independent predictor of clinical outcome may at least partly reflect the relatively limited power of AR in breast cancer.

Androgens and breast cancer

The role of androgens on breast cancer development and progression has not been fully elucidated. Several in vivo and in vitro studies demonstrate that androgens have an inhibitory effect on the mammary epithelium, whereas the majority of epidemiological studies report a positive association between high androgen levels and risk of breast cancer. Expression of the androgen receptor is a positive prognostic factor. Understanding the role of androgens in breast carcinogenesis is important because many women use testosterone replacement for the alleviation of symptoms brought on by menopause, in particular high-risk women who undergo surgical menopause at an early age. We overview the literature examining a role of androgens in the etiology of breast cancer.

Differential effects of exogenous androgen and an androgen receptor antagonist in the peri- and postpubertal murine mammary gland

There is emerging evidence that androgens inhibit proliferation of normal and malignant breast epithelial cells, but the actions of androgens in normal mammary gland morphogenesis are not well understood. In this study, we investigated whether development of the murine mammary gland could be altered by stimulating or suppressing androgen receptor (AR) signaling in vivo. Intact virgin female mice aged 5 wk (midpuberty) or 12 wk (postpuberty) were implanted with slow-release pellets containing either placebo, 5α-dihydrotestosterone (1.5 mg) or the AR antagonist flutamide (60 mg). Treatment with 5α-dihydrotestosterone from midpuberty to 12 wk of age-retarded ductal extension by 40% (P = 0.007), but treatment from 12-21 wk had no significant effect on gland morphology. In contrast, inhibition of AR signaling with flutamide from midpuberty had no effect on the mammary gland, but flutamide treatment from 12-21 wk increased ductal branching (P = 0.004) and proliferation (P = 0.03) of breast epithelial cells. The increased proliferation in flutamide-treated mice was not correlated with serum estradiol levels or estrogen receptor-α (ERα) expression. In control mice, the frequency and intensity of AR immunostaining in mammary epithelial cells was significantly increased in the 12- to 21-wk treatment group compared with the 5- to 12-wk group (P < 0.001). In contrast, no change in ERα occurred, resulting in a marked increase in the AR to ERα ratio from 0.56 (±0.12) to 1.47 (±0.10). Our findings indicate that androgen signaling influences development and structure of the adult mammary gland and that homeostasis between estrogen and androgen signaling in mature glands is critical to constrain the proliferative effects of estradiol.

Investigating and critically appraising the expression and potential role of androgen receptor in breast carcinoma

The potential role of the androgen receptor (AR) as a predictive or prognostic factor in breast cancer remains unclear. We aimed to determine the prognostic significance of AR in a cohort of breast carcinomas with long-term follow-up and to critically appraise this in the context of existing literature. Four hundred and eight cases of invasive breast cancer were incorporated into tissue microarrays (TMAs). All received tamoxifen and comprised 108 cases which relapsed and 300 cases which did not. Mean follow-up time for the former was 84 months (range 1-142, SD 38.8) and for the latter was 77 months (range 11-229, SD 49.7). TMAs were immunohistochemically stained with AR and scored as a continuous variable and using the Allred score. AR expression was significantly associated with grade, recurrence on tamoxifen, non-breast cancer death estrogen receptor alpha (ERα) and progesterone receptor (PR). AR correlated significantly with better overall survival (OS) and disease-free survival (DFS) using an Allred cut-off of 4 (log rank=0.0053 and 0.0044, respectively), and 20% positive tumor cells (log rank=0.0027 and 0.0059, respectively). AR expression was additionally associated with a reduced risk of recurrence following endocrine therapy. In summary, AR positive breast tumors have better OS and DFS and are less likely to recur following endocrine treatment.

Androgen receptor expression and breast cancer survival in postmenopausal women

PURPOSE

Androgen receptor (AR) is commonly expressed in breast cancers. However, the association between tumor AR status and breast cancer survival is uncertain. Hence, we examined the association between AR status and breast cancer survival in the Nurses' Health Study (NHS).

EXPERIMENTAL DESIGN

It was a prospective study of postmenopausal women enrolled in the Nurses' Health Study with stage I to III breast cancer diagnosed between 1976 and 1997 and followed from the date of diagnosis until January 1, 2008 or death. Analyses were conducted using Kaplan-Meier methods and Cox proportional hazard models, to determine the association of AR status with survival outcomes adjusting for covariates.

RESULTS

Among 1467 breast cancers, 78.7% were AR-positive (AR+). Among 1,164 estrogen receptor (ER)-positive cases, 88.0% were AR+. AR positivity was associated with a significant reduction in breast cancer mortality (HR, 0.68; 95% CI, 0.47-0.99) and overall mortality (HR, 0.70; 95% CI, 0.53-0.91) after adjustment for covariates. In contrast, among women with ER-negative tumors (303 cases), 42.9% were AR+. There was a nonsignificant association between AR status and breast cancer death (HR, 1.59; 95% CI, 0.94-2.68).

CONCLUSIONS

The association of AR status and breast cancer survival is dependent on ER status. In particular, AR expression was associated with a more favorable prognosis among women with ER-positive tumors. Thus, determination of AR status may provide additional information on prognosis for postmenopausal women with breast cancer, and provide novel opportunities for targeted therapy.