Increased androgen receptor expression in estrogen receptor-positive/progesterone receptor-negative breast cancer

Nuclear receptors in cancer: Unveiling theranostic potentials and innovative therapeutic strategies

Nuclear receptors (NRs) include a family of 48 transcription factors (TFs) that regulate gene expression implicated in biological processes such as cell proliferation, differentiation, metabolism, and immune response. Cancer development has been widely linked to the dysregulation of NRs and their signaling pathways, providing promising targets for therapeutic applications. Recent progress in OMIC approaches and high-throughput drug screening has facilitated the emergence of biomolecules, especially phytochemicals, as potential substitutes for synthetic anti-cancer drugs. This review aims to highlight the anticancer potency of diverse classes of biocompounds that target NRs, including phytocompounds, dietary components, venom constituents, microbial metabolites, as well as many small molecules generated from computer-aided drug design (CADD) approaches in the design of innovative and safe treatments. We examine critically the preclinical and clinical trials investigating these candidates for preventing and treating cancer, focusing on their modes of action, their proven efficacy, and their limitations. In addition, we underline significant molecular processes modulated by these natural compounds, highlighting their ability to surmount drug resistance and minimize the toxic effects of standard treatments. Overall, we believe this work has the potential to pave the way for new paradigms in identifying innovative therapeutic options for NR-mediated management of specific types of cancer.

Molecular Targets of Minor Cannabinoids in Breast Cancer: In Silico and In Vitro Studies

BACKGROUND

Breast cancer therapy has been facing remarkable changes. Classic treatments are now combined with other therapies to improve efficacy and surpass resistance. Indeed, the emergence of resistance demands the development of novel therapeutic approaches. Due to key estrogen signaling, estrogen receptor-positive (ER+) breast cancer treatment has always been focused on aromatase inhibition and ER modulation. Lately, the effects of phytocannabinoids, mainly Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), have been evaluated in different cancers, including breast. However, Cannabis sativa contains more than 120 phytocannabinoids less researched and understood.

METHODS

Here, we evaluated, both in silico and in vitro, the ability of 129 phytocannabinoids to modulate important molecular targets in ER+ breast cancer: aromatase, ER, and androgen receptor (AR).

RESULTS

In silico results suggested that some cannabinoids may inhibit aromatase and act as ERα antagonists. Nine selected cannabinoids showed, in vitro, potential to act either as ER antagonists with inverse agonist properties, or as ER agonists. Moreover, these cannabinoids were considered as weak aromatase inhibitors and AR antagonists with inverse agonist action.

CONCLUSIONS

Overall, we present, for the first time, a comprehensive analysis of the actions of the phytocannabinoids in targets of ER+ breast tumors, pointing out their therapeutic potential in cancer and in other diseases.

Mechanistic insights into steroid hormone-mediated regulation of the androgen receptor gene

Expression of the androgen receptor is key to the response of cells and tissues to androgenic steroids, such as testosterone or dihydrotestosterone, as well as impacting the benefit of hormone-dependent therapies for endocrine diseases and hormone-dependent cancers. However, the mechanisms controlling androgen receptor expression are not fully understood, limiting our ability to effectively promote or inhibit androgenic signalling therapeutically. An autoregulatory loop has been described in which androgen receptor may repress its own expression in the presence of hormone, although the molecular mechanisms are not fully understood. In this work, we elucidate the mechanisms of autoregulation and demonstrate, for the first time, that a similar repression of the AR gene is facilitated by the progesterone receptor. We show that the progesterone receptor, like the androgen receptor binds to response elements within the AR gene to effect transcriptional repression in response to hormone treatment. Mechanistically, this repression involves hormone-dependent histone deacetylation within the AR 5'UTR region and looping between sequences in intron 2 and the transcription start site (TSS). This novel pathway controlling AR expression in response to hormone stimulation may have important implications for understanding cell or tissue selective receptor signalling.

Core Needle Biopsy Accuracy for Androgen Receptor Expression in Invasive Breast Cancer

OBJECTIVE

 Breast cancer (BC) biomarkers, such as hormone receptors expression, are crucial to guide therapy in BC patients. Antiandrogens have been studied in BC; however, limited data are available on androgen receptor (AR) expression test methodology. We aim to report the core needle biopsy (CNB) accuracy for AR expression in BC.

METHODS

 Patients diagnosed with stage I-III invasive BC from a single institution were included. Androgen receptor expression was evaluated by immunohistochemistry (IHC) using 1 and 10% cutoff and the AR expression in surgical specimens (SS) was the gold standard. Kappa coefficients were used to evaluate the intraprocedural agreement.

RESULTS

 A total of 72 patients were included, with a mean age of 61 years old and 84% were Luminal A or B tumors. The prevalence of AR expression in all BC samples was 87.5% using a cutoff ≥ 10% in SS. With a cutoff value ≥ 1%, CNB had an accuracy of 95.8% (Kappa value = 0.645; 95% confidence interval [CI]: 0.272-1.000; p < 0.001) and 86.1% (Kappa value = 0.365; 95% CI: 0.052-0.679; p < 0.001) when ≥ 10% cutoff was used for AR positivity. Androgen receptor expression in CNB (cutoff ≥ 1%) had a sensitivity of 98.5%, specificity of 60%, positive predictive value of 97.0%, and a negative predictive value of 76.9% in the detection of AR expression in SS.

CONCLUSION

 Core needle biopsy has good accuracy in evaluating AR expression in BC. The accuracy of CNB decreases with higher cutoff values for AR positivity.

The Prognostic Values of Androgen Receptor in Breast Cancer

CONTEXT.—

Whether androgen receptor (AR) expression can predict prognosis in breast cancer is under debate.

OBJECTIVE.—

To analyze, retrospectively, the prognostic and treatment-predictive ability of AR status in breast cancer.

DESIGN.—

A total of 5765 patients diagnosed with primary invasive breast cancer without distant metastasis in the adjuvant setting were analyzed. The propensity score-matching method was used to develop a new cohort of 3978 patients (1989 patients each) in which important prognostic factors were balanced.

RESULTS.—

Positive AR expression is an independent prognostic factor for disease-free survival and overall survival. Estrogen receptor (ER)+ and progesterone receptor (PR)+ AR+ breast cancer patients had the longest survival, whereas ER-PR-AR- breast cancer patients had the shortest survival. The ER/PR/AR combinations could not predict the treatment effects for adjuvant trastuzumab but could be used for adjuvant chemotherapy and endocrine therapy selection. The worst survival was found in ER+PR-AR- patients receiving toremifene, ER+PR-AR+ patients receiving exemestane, ER+PR+AR- patients receiving anthracycline, and ER-PR-AR+ patients receiving taxanes. ER+PR-AR-, ER-PR-AR+, and ER-PR-AR- patients were associated with the worst survival among those who received radiotherapy and anthracycline plus taxanes.

CONCLUSIONS.—

AR in combination with ER and PR could predict the prognosis and treatment effects of chemotherapy, endocrine therapy, and radiotherapy in the adjuvant setting.

Androgen receptor expression and its prognostic value in T1N0 luminal/HER2- breast cancer

Purpose: The authors aimed to evaluate the prognostic and predictive value of androgen receptor (AR) expression in patients with luminal/human EGFR2 negative (HER2-) T1N0 breast cancer. Methods: The cohort in this retrospective study comprised 471 patients with luminal/HER2- T1N0 breast cancer who had undergone surgery between 2013 and 2017 in the authors' center. Results: Androgen receptor (AR)+ tumors were associated with favorable characteristics. AR+ patients had better 5-year recurrence-free survival rates and the risk of recurrence was greater for AR- than for AR+ patients. AR- status predicted the failure of adjuvant endocrine therapy with aromatase inhibitors and of adjuvant chemotherapy with docetaxel plus cyclophosphamide. Conclusion: AR+ expression is significantly related to a better prognosis. AR expression may be an additional biomarker for both endocrine and chemotherapy responsiveness.

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.

Is it time to consider the Androgen receptor as a therapeutic target in breast cancer?

Breast cancer (BC) is a heterogeneous disease and the most prevalent malignant tumor in women worldwide. The majority of BC cases are positive for estrogen receptor (ER) and progesterone receptor (PgR), both known to be involved in cancer pathogenesis, progression, and invasion. In line with this, hormonal deprivation therapy appears to be a useful tool and an effective treatment for these BC subtypes. Unfortunately, prognosis among patients with hormone-negative tumors or therapy-refractory and metastatic patients remains poor. Novel biomarkers are urgently needed in order to predict the course of the disease, make better therapy decisions and improve the overall survival of patients. In this respect, the androgen receptor (AR), a member of the hormonal nuclear receptor superfamily and ER and PgR, emerges as an interesting feature widely expressed in human BCs. Despite the advances, the precise tumorigenic mechanism of AR and the role of its endogenous ligands are yet not well-understood. In this review, we aim to elaborate on the prognostic impact of AR expression and current AR-targeting approaches based on previous studies investigating AR's role in different BC subtypes.

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.

Progesterone receptors in normal breast development and breast cancer

Progesterone receptors (PR) play a pivotal role in many female reproductive tissues such as the uterus, the ovary, and the mammary gland (MG). Moreover, PR play a key role in breast cancer growth and progression. This has led to the development and study of different progestins and antiprogestins, many of which are currently being tested in clinical trials for cancer treatment. Recent reviews have addressed the role of PR in MG development, carcinogenesis, and breast cancer growth. Thus, in this review, in addition to making an overview on PR action in normal and tumor breast, the focus has been put on highlighting the still unresolved topics on hormone treatment involving PR isoforms and breast cancer prognosis.