Androgen receptor gene expression in primary breast cancer

Tamoxifen-predictive value of gene expression signatures in premenopausal breast cancer: data from the randomized SBII:2 trial

BACKGROUND

Gene expression (GEX) signatures in breast cancer provide prognostic information, but little is known about their predictive value for tamoxifen treatment. We examined the tamoxifen-predictive value and prognostic effects of different GEX signatures in premenopausal women with early breast cancer.

METHODS

RNA from formalin-fixed paraffin-embedded tumor tissue from premenopausal women randomized between two years of tamoxifen treatment and no systemic treatment was extracted and successfully subjected to GEX profiling (n = 437, NanoString Breast Cancer 360™ panel). The median follow-up periods for a recurrence-free interval (RFi) and overall survival (OS) were 28 and 33 years, respectively. Associations between GEX signatures and tamoxifen effect were assessed in patients with estrogen receptor-positive/human epidermal growth factor receptor 2-negative (ER+ /HER2-) tumors using Kaplan-Meier estimates and Cox regression. The prognostic effects of GEX signatures were studied in the entire cohort. False discovery rate adjustments (q-values) were applied to account for multiple hypothesis testing.

RESULTS

In patients with ER+/HER2- tumors, FOXA1 expression below the median was associated with an improved effect of tamoxifen after 10 years with regard to RFi (hazard ratio [HR]FOXA1(high) = 1.04, 95% CI = 0.61-1.76, HRFOXA1(low) = 0.30, 95% CI = 0.14-0.67, qinteraction = 0.0013), and a resembling trend was observed for AR (HRAR(high) = 1.15, 95% CI = 0.60-2.20, HRAR(low) = 0.42, 95% CI = 0.24-0.75, qinteraction = 0.87). Similar patterns were observed for OS. Tamoxifen was in the same subgroup most beneficial for RFi in patients with low ESR1 expression (HRRFi ESR1(high) = 0.76, 95% CI = 0.43-1.35, HRRFi, ESR1(low) = 0.56, 95% CI = 0.29-1.06, qinteraction = 0.37). Irrespective of molecular subtype, higher levels of ESR1, Mast cells, and PGR on a continuous scale were correlated with improved 10 years RFi (HRESR1 = 0.80, 95% CI = 0.69-0.92, q = 0.005; HRMast cells = 0.74, 95% CI = 0.65-0.85, q < 0.0001; and HRPGR = 0.78, 95% CI = 0.68-0.89, q = 0.002). For BC proliferation and Hypoxia, higher scores associated with worse outcomes (HRBCproliferation = 1.54, 95% CI = 1.33-1.79, q < 0.0001; HRHypoxia = 1.38, 95% CI = 1.20-1.58, q < 0.0001). The results were similar for OS.

CONCLUSIONS

Expression of FOXA1 is a promising predictive biomarker for tamoxifen effect in ER+/HER2- premenopausal breast cancer. In addition, each of the signatures BC proliferation, Hypoxia, Mast cells, and the GEX of AR, ESR1, and PGR had prognostic value, also after adjusting for established prognostic factors. Trial registration This trial was retrospectively registered in the ISRCTN database the 6th of December 2019, trial ID: https://clinicaltrials.gov/ct2/show/ISRCTN12474687 .

MYC Deregulation and PTEN Loss Model Tumor and Stromal Heterogeneity of Aggressive Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) patients have a poor prognosis and few treatment options. Mouse models of TNBC are important for development of new therapies, however, few mouse models represent the complexity of TNBC. Here, we develop a female TNBC murine model by mimicking two common TNBC mutations with high co-occurrence: amplification of the oncogene MYC and deletion of the tumor suppressor PTEN. This Myc;Ptenfl model develops heterogeneous triple-negative mammary tumors that display histological and molecular features commonly found in human TNBC. Our research involves deep molecular and spatial analyses on Myc;Ptenfl tumors including bulk and single-cell RNA-sequencing, and multiplex tissue-imaging. Through comparison with human TNBC, we demonstrate that this genetic mouse model develops mammary tumors with differential survival and therapeutic responses that closely resemble the inter- and intra-tumoral and microenvironmental heterogeneity of human TNBC, providing a pre-clinical tool for assessing the spectrum of patient TNBC biology and drug response.

Germline Mutations in 32 Cancer Susceptibility Genes by Next-Generation Sequencing among Breast Cancer Patients

INTRODUCTION

BRCA1/2 germline mutations are the most well-known genetic determinants for breast cancer. However, the distribution of germline mutations in non-BRCA1/2 cancer susceptibility genes in Chinese breast cancer patients is unclear. The association between clinical characteristics and germline mutations remains to be explored.

METHODS

Consecutive breast cancer patients from Peking University People's Hospital were enrolled. Clinical characteristics were collected, and next-generation sequencing was performed using blood samples of participants to identify pathogenic/likely pathogenic (P/LP) germline mutations in 32 cancer susceptibility genes including homologous recombination repair (HRR) genes.

RESULTS

A total of 885 breast cancer patients underwent the detection of germline mutations. 107 P/LP germline mutations of 17 genes were identified in 116 breast cancer patients including 79 (8.9%) in BRCA1/2 and 40 (4.5%) in 15 non-BRCA1/2 genes. PALB2 was the most frequently mutated gene other than BRCA1/2 but still relatively rare (1.1%). There were 38 novel P/LP germline variants detected. P/LP germline mutations in BRCA1/2 were significantly associated with onset age (p < 0.001), the family history of breast/ovarian cancer (p = 0.010), and molecular subtype (p < 0.001), while being correlated with onset age (p < 0.001), site of breast tumor (p = 0.028), and molecular subtype (p < 0.001) in HRR genes.

CONCLUSIONS

The multiple-gene panel prominently increased the detection rate of P/LP germline mutations in 32 cancer susceptibility genes compared to BRCA1/2 alone. Onset younger than or equal to 45 years of age, bilateral and triple-negative breast cancer patients may be more likely to be recommended for detecting P/LP germline mutations in HRR genes.

Pharmacological Targeting of Androgen Receptor Elicits Context-Specific Effects in Estrogen Receptor-Positive Breast Cancer

Androgen receptor (AR) is expressed in 80% to 90% of estrogen receptor α-positive (ER+) breast cancers. Accumulated evidence has shown that AR is a tumor suppressor and that its expression is associated with improved prognosis in ER+ breast cancer. However, both a selective AR agonist (RAD140) and an AR inhibitor (enzalutamide, ENZ) have shown a therapeutic effect on ER+ breast cancer, so the potential for clinical application of AR-targeting therapy for ER+ breast cancer is still in dispute. In this study, we evaluated the efficacy of ENZ and RAD140 in vivo and in vitro in AR+/ER+ breast cancer models, characterizing the relationship of AR and ER levels to response to AR-targeting drugs and investigating the alterations of global gene expression and chromatin binding of AR and ERα after ENZ treatment. In the AR-low setting, ENZ directly functioned as an ERα antagonist. Cell growth inhibition by ENZ in breast cancer with low AR expression was independent of AR and instead dependent on ER. In AR-high breast cancer models, AR repressed ERα signaling and ENZ promoted ERα signaling by antagonizing AR. In contrast, RAD140 activated AR signaling and suppressed AR-high tumor growth by deregulating ERα expression and blocking ERα function. Overall, analysis of the dynamic efficacies and outcomes of AR agonist, and antagonist in the presence of different AR and ERα levels reveals regulators of response and supports the clinical investigation of ENZ in selected ER+ tumors with a low AR/ER ratio and AR agonists in tumors with a high AR/ER ratio.

SIGNIFICANCE

The ratio of androgen receptor to estrogen receptor in breast cancer dictates the response to AR-targeted therapies, providing guidelines for developing AR-directed treatment strategies for patients with breast cancer.

Prognostic value of androgen receptor expression in different molecular types of breast cancer in women

BACKGROUND

Breast cancer is a common women's disease. Usually, oestrogen is blamed in the aetiology and correlated with the prognosis; however, androgens are recently raising concern about its role in the breast cancer treatment and prognosis.

METHODS

In this study we retrieved archival paraffin blocks of breast cancer patients and stained it for androgen. Thereafter, we compared clinico-epidemiologic parameters, histopathology, neoadjuvant response and recurrence rate and pattern among patients with and without androgen receptor (AR) expression.

RESULTS

In total, 119 patients fulfilled enrolment criteria; AR expression were present in 77.3% of the patients. AR expression was associated with less grade III (6.8% versus 36.4%), and less triple negative (6.2% versus 25%), but similar overall recurrence rate (25% versus 22.2%). However, distant recurrence was significantly higher in androgen positive patients (91.3% versus 33.3% of all recurrences).

CONCLUSION

Androgen expression appears to be common among breast cancer, but with no clear implication in tumour aggressiveness or effect on the rate of recurrence. However, being commonly associated with distant spread may have an impact on survival of the patients.

Clinicopathological features and androgen receptor expression in triple negative breast cancer at Lagos, Nigeria

INTRODUCTION

Androgen receptor (AR) is one of the predominant nuclear hormone receptors in invasive breast cancer and can be explored as a biomarker of response for targeted anti-androgen therapy, especially in the setting of triple negative breast cancer (TNBC). Luminal AR is a distinct subtype amongst TNBC cases following gene expression studies. TNBC is higher in Africans (23%-82%) and African-Americans (29.8%) compared to Caucasian (10%-15%) breast cancer patients; however, there is a paucity of data on AR expression in this population. The aim of this study is to determine the expression of AR and the proportion of AR positive cancers in TNBCs at the Lagos University Teaching Hospital, Lagos, Nigeria.

METHODOLOGY

Out of 99 reviewed cases, 78 formalin fixed, paraffin embedded TNBC cases were assembled into a tissue microarray, stained and analysed for AR expression using immunohistochemistry.

RESULTS

The mean age of the TNBC patients was 49.3 years (range: 20-80 years). The histologic types in this study were invasive carcinoma (no special type) 75.4%; metaplastic carcinoma 21.4%; lobular carcinoma and mucinous carcinoma 1.6% each. Of 61 TNBC cases analysed, 37.7% were AR positive and 62.3% were AR negative, making the latter to become quadruple negative breast cancers. There was a significant association between age and AR expression (p = 0.02). In the subjects that expressed AR positivity, patients below 50 years accounted for 34.8% (8 of 23) while 65.2% (15 of 23) were above 50 years. There was no significant association between AR expression and histologic type or tumour grade.

CONCLUSION

Over a third of this Nigerian TNBC cohort study is AR+. This warrants further exploration of the predictive and prognostic significance of its expression amongst TNBC and the potential for targeted therapy, specifically androgen antagonists to improve the outcome of this disease with limited therapeutic options.

Association of androgen receptor expression with glucose metabolic features in triple-negative breast cancer

Background

Androgen receptor (AR) is a potential therapeutic target in triple-negative breast cancer (TNBC). We aimed to elucidate the association of AR expression with glucose metabolic features in TNBC.

Methods

Two independent datasets were analyzed: FDG PET data of our institution and a public dataset of GSE135565. In PET analysis, patients with TNBC who underwent pretreatment PET between Jan 2013 and Dec 2017 were retrospectively enrolled. Clinicopathologic features and maximum standardized uptake value (SUVmax) of tumors were compared with AR expression. In GSE135565 dataset, glycolysis score was calculated by the pattern of glycolysis-related genes, and of which association with SUVmax and AR gene expression were analyzed.

Results

A total of 608 female patients were included in the PET data of our institution. SUVmax was lower in AR-positive tumors (P < 0.001) and correlated with lower AR expression (rho = –0.26, P < 0.001). In multivariate analysis, AR was a deterministic factor for low SUVmax (P = 0.012), along with other key clinicopathologic features. In the GSE135565 dataset, AR expression also exhibited a negative correlation with SUVmax (r = –0.34, P = 0.001) and the glycolysis score (r = –0.27, P = 0.013).

Conclusions

Low glucose metabolism is a signature of AR expression in TNBC. It is suggested that evaluation of AR expression status needs to be considered in clinical practice particularly in TNBC with low glucose metabolism.

Luminal androgen receptor (LAR) subtype of triple-negative breast cancer: molecular, morphological, and clinical features

According to the classification presented by Lehmann BD (2016), triple-negative breast cancer (TNBC) is a heterogeneous group of malignant tumors with four specific subtypes: basal-like (subtype 1 and subtype 2), mesenchymal, and luminal androgen receptor (LAR) subtypes. The basal-like subtypes of carcinomas predominate in this group, accounting for up to 80% of all cases. Despite the significantly lower proportions of mesenchymal and LAR variants in the group of breast carcinomas with a TNBC profile, such tumors are characterized by aggressive biological behavior. To this end, the LAR subtype is of particular interest, since the literature on such tumors presents different and even contradictory data concerning the disease course and prognosis. This review is devoted to the analysis of the relevant literature, reflecting the main results of studies on the molecular properties and clinical features of the disease course of LAR-type TNBC carcinomas.

Androgen Receptor: A New Marker to Predict Pathological Complete Response in HER2-Positive Breast Cancer Patients Treated with Trastuzumab Plus Pertuzumab Neoadjuvant Therapy

(1) Background: Neoadjuvant therapy is the main therapeutic strategy for human epidermal growth factor receptor 2 (HER2)-positive breast cancer patients, and the combination of trastuzumab and pertuzumab (HP) has become a routine treatment. How to predict and screen patients who are less likely to respond to neoadjuvant therapy is the focus of research. The androgen receptor (AR) is a biomarker that is widely expressed in all breast cancer subtypes and is probably related to treatment response and prognosis. In this study, we investigated the relationship between AR expression and treatment response in HER2-positive breast cancer patients treated with HP neoadjuvant therapy. (2) Methods: We evaluated early breast cancer patients treated with HP neoadjuvant therapy from Jan. 2019 to Oct. 2020 at Peking University First Hospital Breast Cancer Center. The inclusion criteria were as follows: early HER2-positive breast cancer patients diagnosed by core needle biopsy who underwent both HP neoadjuvant therapy and surgery. We compared the clinical and pathological features between pathological complete response (pCR) and non-pCR patients. (3) Results: We included 44 patients. A total of 90.9% of patients received neoadjuvant therapy of taxanes, carboplatin, trastuzumab and pertuzumab (TCHP), and the total pCR rate was 50%. pCR was negatively related to estrogen receptor (ER) positivity (OR 0.075 [95% confidence interval (CI) 0.008–0.678], p = 0.021) and positively related to high expression levels of AR (OR 33.145 [95% CI 2.803–391.900], p = 0.005). We drew a receiver operating characteristic (ROC) curve to assess the predictive value of AR expression for pCR, and the area under the curve was 0.737 (95% CI 0.585–0.889, p = 0.007). The optimal cutoff of AR for predicting pCR was 85%. (4) Conclusion: AR is a potential marker for the prediction of pCR in HER2-positive breast cancer patients treated with HP neoadjuvant therapy.

Androgen receptor in breast cancer: The "5W" questions

Androgen receptor (AR) is expressed in 60-70% of breast cancers (BCs) and the availability of anti-AR compounds, currently used for treating prostate cancer, paves the way to tackle specifically AR-positive BC patients. The prognostic and predictive role of AR in BC is a matter of debate, since the results from clinical trials are not striking, probably due to both technical and biological reasons. In this review, we aimed to highlight WHAT is AR, describing its structure and functions, WHAT to test and HOW to detect AR, WHERE AR should be tested (on primary tumor or metastasis) and WHY studying this fascinating hormone receptor, exploring and debating on its prognostic and predictive role. We considered AR and its ratio with other hormone receptors, analyzing also studies including patients with ductal carcinoma in situ and with early and advanced BC, as well. We also emphasized the effects that both other hormone receptors and the newly emerging androgen-inducible non coding RNAs may have on AR function in BC pathology and the putative implementation in the clinical setting. Moreover, we pointed out the latest results by clinical trials and we speculated about the use of anti-AR therapies in BC clinical practice.

Abiraterone Acetate in Patients With Castration-Resistant, Androgen Receptor-Expressing Salivary Gland Cancer: A Phase II Trial

PURPOSE

The activity of androgen-deprivation therapy (ADT) in androgen receptor-positive (AR+) salivary gland carcinomas (SGCs) has been established in the past few years. Second-line treatment in castration-resistant patients is still unknown. We investigated the activity of abiraterone acetate as second-line treatment in ADT-resistant, AR+ patients with SGC.

METHODS

This was a single-institution phase II trial. A two-stage Simon's design was applied. The primary end point was confirmed objective response rate. Secondary end points were disease control rate, safety, progression-free survival, and overall survival. Patients were eligible when the following criteria were met: histologic diagnosis of AR-overexpressing SGC, measurable disease according to RECIST 1.1, clinical and/or radiologic progression on ADT, suppressed serum testosterone, and no limits for the number of previous chemotherapy lines. All patients received abiraterone 1 g daily plus prednisone 10 mg and luteinizing hormone-releasing hormone agonist until progression or unacceptable toxicities.

RESULTS

From 2015 to 2019, 24 AR+ patients with SGC (23 men; median age 65.8 years) were treated within the study. The overall response rate was 21% (5 partial responses), with a disease control rate of 62.5%. The median duration of response was 5.82 months. Median progression-free survival was 3.65 months (95% CI, 1.94 to 5.89), and median overall survival was 22.47 months (95% CI, 6.74 to not reached). Objective response to previous ADT did not correlate with the activity of abiraterone. Adverse events (AEs) were recorded in 22 cases (92%) with grade 3 AEs in six patients (25%): fatigue (two), flushing (one), supraventricular tachycardia (one), and two non-drug-related AEs. No drug-related grade 4 or 5 AEs were recorded.

CONCLUSION

Abiraterone plus luteinizing hormone-releasing hormone agonist is active and safe as a second-line option in AR-expressing, castration-resistant SGC.

Intrinsic Subtypes and Androgen Receptor Gene Expression in Primary Breast Cancer. A Meta-Analysis

The androgen receptor (AR) is frequently expressed in breast cancer (BC), but its association with clinical and biological parameters of BC patients remains unclear. Here, we investigated the association of AR gene expression according to intrinsic BC subtypes by meta-analysis of large-scale microarray transcriptomic datasets. Sixty-two datasets including 10315 BC patients were used in the meta-analyses. Interestingly, AR mRNA level is significantly increased in patients categorized with less aggressive intrinsic molecular subtypes including, Luminal A compared to Basal-like (standardized mean difference, SMD: 2.12; 95% confidence interval, CI: 1.88 to 2.35; p < 0.001) or when comparing Luminal B to Basal-like (SMD: 1.53; CI: 1.33 to 1.72; p < 0.001). The same trend was observed when analyses were performed using immunohistochemistry-based surrogate subtypes. Consistently, the AR mRNA expression was higher in patients with low histological grade (p < 0.001). Furthermore, our data revealed higher levels of AR mRNA in BC patients expressing either estrogen or progesterone receptors (p < 0.001). Together, our findings indicate that high mRNA levels of AR are associated with BC subgroups with the less aggressive clinical features.

Steroid Ligands, the Forgotten Triggers of Nuclear Receptor Action; Implications for Acquired Resistance to Endocrine Therapy

PURPOSE

There is strong epidemiologic evidence indicating that estrogens may not be the sole steroid drivers of breast cancer. We hypothesize that abundant adrenal androgenic steroid precursors, acting via the androgen receptor (AR), promote an endocrine-resistant breast cancer phenotype.

EXPERIMENTAL DESIGN

AR was evaluated in a primary breast cancer tissue microarray (n = 844). Androstenedione (4AD) levels were evaluated in serum samples (n = 42) from hormone receptor-positive, postmenopausal breast cancer. Levels of androgens, progesterone, and estradiol were quantified using LC/MS-MS in serum from age- and grade-matched recurrent and nonrecurrent patients (n = 6) before and after aromatase inhibitor (AI) therapy (>12 months). AR and estrogen receptor (ER) signaling pathway activities were analyzed in two independent AI-treated cohorts.

RESULTS

AR protein expression was associated with favorable progression-free survival in the total population (Wilcoxon, P < 0.001). Pretherapy serum samples from breast cancer patients showed decreasing levels of 4AD with age only in the nonrecurrent group (P < 0.05). LC/MS-MS analysis of an AI-sensitive and AI-resistant cohort demonstrated the ability to detect altered levels of steroids in serum of patients before and after AI therapy. Transcriptional analysis showed an increased ratio of AR:ER signaling pathway activities in patients failing AI therapy (t test P < 0.05); furthermore, 4AD mediated gene changes associated with acquired AI resistance.

CONCLUSIONS

This study highlights the importance of examining the therapeutic consequences of the steroid microenvironment and demonstrable receptor activation using indicative gene expression signatures.

Cancer stem cells in TNBC

Triple-negative breast cancer (TNBC) is a broad collection of breast cancer that tests negative for estrogen receptors (ER), progesterone receptors (PR), and excess human epidermal growth factor receptor 2 (HER2) protein. TNBC is considered to have poorer prognosis than other types of breast cancer because of a lack of effective therapeutic targets. The success of precision cancer therapies relies on the clarification of key molecular mechanisms that drive tumor growth and metastasis; however, TNBC is highly heterogeneous in terms of their cellular lineage composition and the molecular nature within each individual case. In particular, the rare and sometimes slow cycling cancer stem cells (CSCs) can provide effective means for TNBC to resist various treatments. Single cell analysis technologies, including single-cell RNA-seq (scRNA-seq) and proteomics, provide an avenue to unravel patient-level intratumoral heterogeneity by identifying CSCs populations, CSC biomarkers and the range of tumor microenvironment cellular constituents that contribute to tumor growth. This review discusses the emerging evidence for the role of CSCs in driving TNBC incidence and the therapeutic implications in manipulating molecular signaling against this rare cell population for the control of this deadly disease.

Hormone Receptor Expression Variations in Normal Breast Tissue: Preliminary Results of a Prospective Observational Study

Normal breast tissue undergoes great variations during a woman’s life as a consequence of the different hormonal stimulation. The purpose of the present study was to examine the hormonal receptor expression variations according to age, menstrual cycle, menopausal state and body mass index. To this purpose, 49 tissue samples of normal breast tissue, obtained during surgery performed for benign and malignant conditions, were immunostained with Estrogen (ER), Progesterone (PR) and Androgen receptors (AR). In addition, Ki67 and Gross Cystic Disease Fluid Protein were studied. The data obtained revealed a great variability of hormone receptor expression. ER and AR generally increased in older and post-menopausal women, while young women presented a higher proliferative rate, evaluated with Ki67. PR increase was observed in women with BMI higher than 25. The different hormonal receptor expression could favor the development of breast cancer.

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

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

Diagnostic and prognostic role of NR3C4 in breast cancer through a genomic network understanding

The androgen receptor (AR, NR3C4) is believed to participate in the development of breast cancer, but its molecular mechanism and role in prognosis is still controversial and opaque. This study aimed to explore the expression, associations with clinicopathologic features and underlying molecular mechanisms of AR in breast cancer. The present study investigated invasive breast carcinoma through comprehensive bioinformatics. The expression and mutation rate of AR in breast cancer was obtained from the TCGA database. Training survival prediction analysis was applied to the data extracted from the KM plotter database. The prediction of the survival cohort was validated using the bcGenExMiner database in breast cancer molecular subgroups. Represented immunohistochemical images of AR and its related expression with the molecular subtype status were generated. The underlying molecular mechanism for AR in breast cancer was analyzed with the GEO dataset and Gene Ontology. A protein-to-protein interaction network and core pathways were constructed to show the protein functions with AR. Our results show that AR expression was significantly higher in cancerous tissue than in normal breast tissue and differentially expressed in the clinical stages. AR would also generally be considered as a favorable prognostic biomarker when including the major molecular subtypes of breast cancer. AR IHC staining could be easily used in clinical applications. The major molecular functions for AR were regulating the cell cycle checkpoints and chromatin remodeling. Our investigation showed that AR expression level could be used as a favorable and independent prognostic prediction factor for the disease-free survival time in breast cancer, especially for the ER-positive subgroup. However, AR was not a sensitive prognostic biomarker for the prediction of overall survival time or for the PR and TBC subgroups. In terms of the underlying molecular mechanism, AR may mainly participate in the cell cycle checkpoints related to the G1/S transition of the mitotic cell cycle to control the subdivision of the epithelial terminal unit and chromatin remodeling in breast cancer.

miR-9-5p as a Regulator of the Androgen Receptor Pathway in Breast Cancer Cell Lines

Breast cancer (BC) is the most diagnosed carcinoma and the leading cause of cancer death in female over 100 countries. Thanks to the advance in therapeutic strategies, patients' survival has improved. However, the lack of response to treatments and drug resistance are still a main concern, demanding for new therapeutic approaches, in particular for the advanced stages of the disease. Androgen receptor (AR) is gaining increasing interest as a fourth targetable receptor in BC, however, its regulation in BC cells is still poorly understood. MicroRNAs (miRNAs) regulate gene expression post-transcriptionally. Here, we identified miR-9-5p as an inhibitor of AR expression, we validated the inverse correlation between miR-9-5p and AR in primary BC samples and we further identified a feedback loop in which androgen agonists of AR up-regulate miR-9-5p. We also provided evidence that miR-9-5p elicits anti-proliferative effects in BC cell lines regardless of their estrogen receptor status. Finally, we showed that miR-9-5p can revert AR-downstream signaling even in presence of AR-agonists, highlighting the role of this miR in the hormonal response of BC. In conclusion, this study supports the role of miR-9-5p as an anti-proliferative miR in BC and as a central modulator of AR-signaling response to circulating androgens in BC.

Novel Agents for Metastatic Triple-Negative Breast Cancer: Finding the Positive in the Negative

Metastatic triple-negative breast cancer (TNBC) is associated with a poor prognosis, and the development of better therapeutics represents a major unmet clinical need. Although the mainstay of treatment of metastatic TNBC is chemotherapy, advances in genomics and molecular profiling have helped better define subtypes of TNBC with distinct biologic drivers to guide the therapeutic development of targeted therapies, including AKT inhibitors for PI3K/AKT-altered TNBC, checkpoint inhibitors for PD-L1-positive TNBC, and PARP inhibitors for BRCA1/2 mutant TNBC. This progress may ultimately convert TNBC from a disease traditionally defined by the absence of therapeutically actionable receptors to one that is defined by the presence of discrete molecular targets with therapeutic implications. Furthermore, antibody drug conjugates have emerged as an important therapeutic strategy to target genomically complex tumors that lack actionable oncogenes but have overexpressed actionable surface receptors such as trop-2. In this article, we discuss promising novel agents for advanced TNBC, some of which have been incorporated into current clinical practice, and others that will likely change the therapeutic landscape and redefine the TNBC terminology in the near future.

Lack of Androgen Receptor Expression Selects for Basal-Like Phenotype and Is a Predictor of Poor Clinical Outcome in Non-Metastatic Triple Negative Breast Cancer

Background: Androgen receptor (AR) has emerged as a significant favorable prognostic indicator in estrogen receptor expressing (ER⁺) breast cancer (BCa); however, its clinical and biological relevance in triple negative breast cancer (TNBC) and association with cancer stem cell (CSC) markers remain ambiguous. Methods: We examined the immunohistochemical expression of AR in a cohort of stage I-III TNBC cases (n = 197) with a long-term clinical follow-up data (mean follow-up = 53.6 months). Significance of AR expression was correlated with prognostic biomarkers including cancer stem cell markers (CD44, CD24, and ALDH1), basal markers (CK5, CK14, and nestin), proliferation marker (ki-67), apoptotic marker (Bcl-2), and COX-2. Expression of CK5 and nestin was used for the categorization of TNBC into basal (TN, CK5⁺, and/or nestin⁺) and non-basal (TN, CK5^-, and/or nestin^-) phenotypes, and Kaplan-Meier curves were used for estimation of overall survival and breast cancer-specific survival (BCSS). Results: AR expression was observed in 18.8% of non-metastatic TNBC tumors. Expression of AR correlated with lower grade (P < 0.001) and conferred a favorable prognostic significance in patients with axillary lymph node metastasis (P = 0.005). Lack of AR expression correlated with expression of CSC phenotype (CD44⁺/CD24^-) (P < 0.001), COX-2 (P = 0.02), basal markers (CK5: P = 0.03), and nestin (P = 0.01). Basal-like phenotype (TN, CK5⁺, and/or nestin⁺) correlated with quadruple-negative breast cancer (QNBC) and showed a significant association with adverse prognostic markers including high proliferation index (P < 0.001), expression of COX-2 (P = 0.009), and CSC phenotype (CD44⁺/CD24^-: P = 0.01). Expression of AR remained an independent prognostic indicator for improved overall survival (P = 0.003), whereas basal-like phenotype was associated with an adverse BCSS (P = 0.013). Conclusions: Assessment of AR and basal markers identified biologically and clinically distinct subgroups of TNBC. Expression of AR defined a low-risk TNBC subgroup associated with improved overall survival, whereas expression of basal markers (CK5 and nestin) identified a high-risk subgroup associated with adverse BCSS. Integration of immunohistochemical analysis of AR and basal biomarkers to the assessment of TNBC tumors is expected to improve the prognostication of an otherwise heterogeneous disease.

Pathology of triple negative breast cancer

Triple negative breast cancer (TNBC) is a subtype of breast tumor lacking hormone receptors expression and HER2 gene amplification and represents 24 % of newly diagnosed breast neoplasms. In this review, pathological aspects of triple-negative breast cancer are illustrated, with particular attention to the seminal studies that defined this subtype of breast cancer by a molecular point of view. This paper also focuses on practical issues raised in clinical routine by the introduction of genetic expression breast cancer profiling and the innovative prognostic and predictive impact on triple-negative breast cancer pathology. Moreover, histopathological aspects of triple-negative neoplasms are also mentioned, underlying the importance of histologic diagnosis of particular cancer subtypes with decisive impact on clinical outcome. Importantly, focus on new therapeutic frontier represented by immunotherapy is illustrated, with particular mention of immune checkpoint inhibitors introduction in TNBC therapy and their impact on future treatments.