Affinity For Androgen Receptor Research Articles

In vitro combination effects of plant-derived quercetin with synthetic bicalutamide on prostate cancer and normal cell lines: in silico comparison.

Prostate cancer is the second most frequent and the fifth greatest cause of death in men. Although diet has been connected to the prevalence of cancer in addition to other factors, the relation between cancer and prevention is weak. Treatment options are at risk due to cell resistance. To identify new combinations, we tried plant-derived quercetin with bicalutamide on cell lines. To determine the cytotoxicity and apoptotic potential of plant-derived quercetin and its combination, MTT [3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide] and dual stain assays were performed. In silico protein-ligand interaction was performed to support the in vitro findings. A thin layer, column, and high-performance chromatography were used to purify quercetin along with an authentic sample. In the cytotoxic study, quercetin was minimized by 80% similar to bicalutamide and a combination of quercetin and bicalutamide by 50% when compared to controls by 2%. Quercetin and bicalutamide showed a similar binding affinity for androgen receptors (9.7 and 9.8), hub genes (10.8 and 10.0), and a few other PCa-related genes (9.4 and 9.1). We propose to conclude that the combination of quercetin plus bicalutamide can be used for chemotherapy if additional in vivo studies are conducted. The intake of foods high in polyphenolic compounds can help to prevent prostate cancer. Examination of quercetin on several cell lines will provide a definite conclusion to combat cancers.

Deciphering the mechanisms and interactions of the endocrine disruptor bisphenol A and its analogs with the androgen receptor

Bisphenol A (BPA) and its various forms used as BPA alternatives in industries are recognized toxic compounds and antiandrogenic endocrine disruptors. These chemicals are widespread in the environment and frequently detected in biological samples. Concerns exist about their impact on hormones, disrupting natural biological processes in humans, together with their negative impacts on the environment and biotic life. This study aims to characterize the interaction between BPA analogs and the androgen receptor (AR) and the effect on the receptor's normal activity. To achieve this goal, molecular docking was conducted with BPA and its analogs and dihydrotestosterone (DHT) as a reference ligand. Four BPA analogs exhibited higher affinity (−10.2 to −8.7 kcal/mol) for AR compared to BPA (−8.6 kcal/mol), displaying distinct interaction patterns. Interestingly, DHT (−11.0 kcal/mol) shared a binding pattern with BPA. ADMET analysis of the top 10 compounds, followed by molecular dynamics simulations, revealed toxicity and dynamic behavior. Experimental studies demonstrated that only BPA disrupts DHT-induced AR dimerization, thereby affecting AR's function due to its binding nature. This similarity to DHT was observed during computational analysis. These findings emphasize the importance of targeted strategies to mitigate BPA toxicity, offering crucial insights for interventions in human health and environmental well-being.

Development and Evaluation of 99mTc Tricarbonyl Complexes Derived from Flutamide with Affinity for Androgen Receptor.

With the objective to develop a potential 99mTc radiopharmaceutical for imaging the androgen receptor (AR) in prostate cancer, four ligands bearing the same pharmacophore derived from the AR antagonist flutamide were prepared, labeled with 99mTc, and their structures corroborated via comparison with the corresponding stable rhenium analogs. All complexes were obtained with high radiochemical purity. Three of the complexes were highly stable, and, due to their favorable physicochemical properties, were further evaluated using AR-positive and AR-negative cells in culture. All complexes exhibited considerable uptake in AR-positive cells, which could be blocked by an excess of flutamide. The efflux from the cells was moderate. They also showed significantly lower uptakes in AR-negative cells, indicating interactions with the AR receptor. However, the binding affinities were considerably reduced by the coordination to 99mTc, and the complex that exhibited the best biological behavior did not show sufficient specificity towards AR-positive cells.

Synthesis, bioactivity, and molecular docking of novel arylpiperazine derivatives as potential AR antagonists.

Prostate cancer is one of the malignant tumors and the second most common malignant tumor in men. Clinically used androgen receptor (AR)–targeted drugs can antagonize androgen and inhibit tumor growth, but these drugs can cause serious resistance problems. To develop novel AR antagonists, 22 kinds of arylpiperazine derivatives were designed and synthesized, and the derivatives 5, 8, 12, 19, 21, 22, 25, and 26 not only showed strong antagonistic potency (>55% inhibition) and binding affinities (IC50 <3 μM) to AR, but also showed stronger inhibitory activity to LNCaP cells versus PC-3 cells. Among them, derivative 21 exhibited the highest binding affinity for AR (IC50 = 0.65 μM) and the highest antagonistic potency (76.2% inhibition). Docking studies suggested that the derivative 21 is primarily bound to the AR-LBP site by the hydrophobic interactions. Overall, those results provided experimental methods for developing novel arylpiperazine derivatives as potent AR antagonists.

Active Antialopecia Chemical Identification of Merremia peltata Leaves and Computational Study toward Androgen Receptor Using Molecular Docking and Molecular Dynamic Simulation

Alopecia is a health condition in which the hair loses its function in some or all of the body. Alopecia occurs due to various genetic, environmental, and nutritional factors. One of the methods developed to treat alopecia is through inhibition of the enzyme 5-α-reductase, which converts testosterone into its more potent metabolite, dihydrotestosterone (DHT). In ethnomedicine, the leaves of Merremia peltata are used by the people of Sulawesi as a remedy for baldness. Therefore, in this study, an in vivo study was conducted on rabbits to investigate the antialopecia activity of the ethanolic extract of M. peltata leaves. The purified M. peltata leaf extract was fractionated using vacuum liquid chromatography with several solvents to produce fractions F1–F5. Each fraction was then retested in vivo in rabbits, and its content was then analyzed by LC-MS. An in silico study was then carried out using minoxidil as a comparison ligand; 17 compounds derived from M. peltata leaves were identified as antialopecia compounds through prediction of molecular interactions and molecular dynamics simulation and prediction of absorption, distribution, metabolism, excretion, and toxicology (ADME-Tox). The assay results showed that fractions F2 and F3 had a better effect on hair growth compared to the positive control, and the test compound obtained from the LC-MS analysis, bufotalinin, had a strong binding energy to the receptor in the molecular docking interaction study: −5.99 kcal/mol compared to −4.8 kcal/mol for minoxidil. Molecular dynamics simulation analysis with complex stability parameters based on solvent-accessible surface area (SASA), principal component analysis (PCA), root mean square deviation (RMSD), and root mean square fluctuation (RMSF) showed that bufotalinin has good affinity for androgen receptors. ADME-Tox prediction for bufotalinin showed good results for the parameters of skin permeability, absorption, and distribution. Therefore, bufotalinin, a steroid compound, is a potential androgen receptor antagonist and could be useful in the treatment of alopecia.

Targeting the androgen receptor signaling pathway in advanced prostate cancer.

This article summarizes current androgen receptor (AR)-directed therapies that have received regulatory approval for the treatment of advanced prostate adenocarcinoma (herein referred to as prostate cancer, PC). PC is an androgen-dependent malignancy in which ligands including testosterone and dihydrotestosterone bind to AR, initiating androgen-AR complex translocation to the nucleus followed by AR-mediated transcription of target genes. Androgen deprivation therapy (ADT), including gonadotropin hormone-releasing hormone (GnRH) agonists with or without AR antagonists (antiandrogens), GnRH antagonists, or bilateral orchiectomy, forms the backbone of treatment for patients with metastatic castration-naive PC and/or castration-resistant PC (CRPC). ADT is also an option for high-risk, early-stage PC after prostatectomy and/or radiation. While ADT is often very effective as initial therapy, resistance ultimately develops despite suppression of gonadal and/or adrenal androgens, leading to CRPC, which is characterized by mechanisms such as reactivation of the AR signaling pathway, AR gene overexpression, and mutations in the ligand-binding domain of AR that lead to disease progression, resulting in increased symptom burden and ultimately death. However, disease in patients with CRPC is still dependent on androgen signaling, and these patients continue on ADT to maintain a castrate level of serum testosterone. Novel hormonal therapies including agents that target AR directly (eg, AR antagonists) are often added to ADT in this setting. Targeting the AR signaling pathway led to the development of second-generation AR antagonists, examples of which include enzalutamide, apalutamide, and darolutamide. These agents do not exhibit partial agonism, possess a higher affinity for AR, and are postulated to improve survival outcomes relative to their first-generation counterparts for patients with CRPC. Lastly, the emergence of ADT, including second-generation AR antagonists, has led to the development of supportive care for treatment-related adverse effects. Major advances have been made in targeting the AR signaling pathway in patients with advanced PC. Further studies are warranted to identify the optimal sequencing of therapies to maximize treatment benefit. Mitigation of treatment-related adverse effects presents new opportunities to advance clinical pharmacy practice.

Synthesis and Evaluation of 18F-Enzalutamide, a New Radioligand for PET Imaging of Androgen Receptors: A Comparison with 16β-18F-Fluoro-5α-Dihydrotestosterone.

16β-18F-fluoro-5α-dihydrotestosterone (18F-FDHT) is a radiopharmaceutical that has been investigated as a diagnostic agent for the assessment of androgen receptor (AR) density in prostate cancer using PET. However, 18F-FDHT is rapidly metabolized in humans and excreted via the kidneys into the urine, potentially compromising the detection of tumor lesions close to the prostate. Enzalutamide is an AR signaling inhibitor currently used in different stages of prostate cancer. Enzalutamide and its primary metabolite N-desmethylenzalutamide have an AR affinity comparable to that of FDHT but are excreted mainly via the hepatic route. Radiolabeled enzalutamide could thus be a suitable candidate PET tracer for AR imaging. Here, we describe the radiolabeling of enzalutamide with 18F. Moreover, the invitro and invivo behavior of 18F-enzalutamide was evaluated and compared with the current standard, 18F-FDHT. Methods:18F-enzalutamide was obtained by fluorination of the nitro precursor. In vitro cellular uptake studies with 18F-enzalutamide and 18F-FDHT were performed in LNCaP (AR-positive) and HEK293 (AR-negative) cells. Competition assays with both tracers were conducted on the LNCaP (AR-positive) cell line. In vivo PET imaging, ex vivo biodistribution, and metabolite studies with 18F-enzalutamide and 18F-FDHT were conducted on athymic nude male mice bearing an LNCaP xenograft in the shoulder. Results:18F-enzalutamide was obtained in 1.4% ± 0.9% radiochemical yield with an apparent molar activity of 6.2 ± 10.3 GBq/µmol. 18F-FDHT was obtained in 1.5% ± 0.8% yield with a molar activity of more than 25 GBq/µmol. Coincubation with an excess of 5α-dihydrotestosterone or enzalutamide significantly reduced the cellular uptake of 18F-enzalutamide and 18F-FDHT to about 50% in AR-positive LNCaP cells but not in AR-negative HEK293 cells. PET and biodistribution studies on male mice bearing a LnCaP xenograft showed about 3 times higher tumor uptake for 18F-enzalutamide than for 18F-FDHT. Sixty minutes after tracer injection, 93% of 18F-enzalutamide in plasma was still intact, compared with only 3% of 18F-FDHT. Conclusion: Despite its lower apparent molar activity, 18F-enzalutamide shows higher tumor uptake and better metabolic stability than 18F-FDHT and thus seems to have more favorable properties for imaging of AR with PET. However, further evaluation in other oncologic animal models and patients is warranted to confirm these results.

An up-to-date evaluation of darolutamide for the treatment of prostate cancer

ABSTRACT Introduction: Currently, in prostate cancer, an increasing number of novel drugs are being used to delay its advancement to metastatic castration-resistant prostate cancer (mCRPC). Apalutamide, enzalutamide, and most recently, darolutamide (novel androgen receptor antagonists) have been approved for nonmetastatic castration-resistant prostate cancer (nmCRPC). Areas covered: The authors have evaluated darolutamide, covering all aspects of the clinical development, competence, and safety profile of the drug. Expert opinion: The unique structure of darolutamide is characterized by a high affinity for androgen receptors and detainment of antagonist activity in mutant isoforms of androgen receptors. In clinical practice, this is the main reason that makes darolutamide exceptional in terms of safety and efficacy compared to other drugs in this category. Darolutamide is considered to have the lowest probability for adverse events (AEs) compared to apalutamide and enzalutamide. Future studies, along with real-world clinical data are warranted to improve personalized treatment strategies as well as sequencing treatment between approved novel drugs.

Darolutamide antagonizes androgen signaling by blocking enhancer and super-enhancer activation.

Prostate cancer (PCa) is one of the most frequent tumor types in the male Western population. Early‐stage PCa and late‐stage PCa are dependent on androgen signaling, and inhibitors of the androgen receptor (AR) axis represent the standard therapy. Here, we studied in detail the global impact of darolutamide, a newly approved AR antagonist, on the transcriptome and AR‐bound cistrome in two PCa cell models. Darolutamide strongly depleted the AR from gene regulatory regions and abolished AR‐driven transcriptional signaling. Enhancer activation was blocked at the chromatin level as evaluated by H3K27 acetylation (H3K27ac), H3K4 monomethylation (H3K4me1), and FOXA1, MED1, and BRD4 binding. We identified genomic regions with high affinities for the AR in androgen‐stimulated, but also in androgen‐depleted conditions. A similar AR affinity pattern was observed in healthy and PCa tissue samples. High FOXA1, BRD4, H3K27ac, and H3K4me1 levels were found to mark regions showing AR binding in the hormone‐depleted setting. Conversely, low FOXA1, BRD4, and H3K27ac levels were observed at regulatory sites that responded strongly to androgen stimulation, and AR interactions at these sites were blocked by darolutamide. Beside marked loss of AR occupancy, FOXA1 recruitment to chromatin was also clearly reduced after darolutamide treatment. We furthermore identified numerous androgen‐regulated super‐enhancers (SEs) that were associated with hallmark androgen and cell proliferation‐associated gene sets. Importantly, these SEs are also active in PCa tissues and sensitive to darolutamide treatment in our models. Our findings demonstrate that darolutamide is a potent AR antagonist blocking genome‐wide AR enhancer and SE activation, and downstream transcription. We also show the existence of a dynamic AR cistrome that depends on the androgen levels and on high AR affinity regions present in PCa cell lines and also in tissue samples.

Targeting prostate cancer cells with enzalutamide-HDAC inhibitor hybrid drug 2-75.

The progression of castration-resistant prostate cancer (CRPC) still relies on the function of androgen receptor (AR), achieved by evolving mechanisms to reactivate AR signaling under hormonal therapy. Histone deacetylase inhibitors (HDACis) disrupt cytoplasmic AR chaperone heat shock protein 90 (Hsp90) via HDAC6 inhibition, leading to AR degradation and growth suppression of prostate cancer (PCa) cells. However, current HDACis are not effective in clinical trials treating CRPC. We designed hybrid molecules containing partial chemical scaffolds of AR antagonist enzalutamide (Enz) and HDACi suberoylanilide hydroxamic acid (SAHA) as new anti-PCa agents. We previously demonstrated that Enz-HDACi hybrid drug 2-75 targets both AR and Hsp90, which inhibits the growth of Enz-resistant C4-2 cells. In the current study, we further investigate the molecular and cellular actions of 2-75 and test its anti-PCa effects in vivo. Compared with Enz, 2-75 had greater AR antagonistic effects by decreasing the stability, transcriptional activity, and nuclear translocation of intracellular AR. In addition to inhibition of full-length AR (FL AR), 2-75 downregulated the AR-V7 variant in multiple PCa cell lines. Mechanistic studies indicated that the AR affinity of 2-75 retains the drug in the cytoplasm of AR + PCa cells and further directs 2-75 to the AR-associated protein complex, which permits localized effects on AR-associated Hsp90. Further, unlike pan-HDACi SAHA, the cytoplasm-retaining property allows 2-75 to significantly inhibit cytoplasmic HDAC6 with limited impact on nuclear HDACs. These selective cytoplasmic actions of 2-75 overcome the unfavorable resistance and toxicity properties associated with classical AR antagonists, HDACis, and Hsp90 inhibitors. Finally, 2-75 showed greater antitumor activities than Enz in vivo on SQ xenografts derived from LNCaP cells. Novel therapeutic strategy using newly designed 2-75 and related AR antagonist-HDACi hybrid drugs has great potential for effective treatment of CRPC.

QSAR Analysis of a Series of Hydantoin-based Androgen Receptor Modulators and Corresponding Binding Affinities.

Androgen receptor (AR), a member of the nuclear hormone receptor superfamily of intracellular ligand-dependent transcription factors, plays an indispensable role in normal male development through the regulation of androgen through the binding with endogenous androgens. Inappropriate amounts of androgens have a severe adverse effect on men. Excessive androgen may contribute to accelerate prostatic hypertrophy, even prostate cancer, while the absence of androgen may result in reduced muscle mass and strength, decreased bone mass, low energy, diminished sexual function and an increased risk of osteoporosis and fracture. In these cases, androgen receptor modulators are important to maintain the normal biological function of AR. So androgen receptor modulators are necessary for human being to improve their happy life index. To explore the relationships between molecular structures and corresponding binding abilities to aid the new AR modulator design, multiple linear regressions (MLR) are employed to analyze a series of hydantoin analogues, which can bind to androgen receptor acting as AR modulators. The obtained optimum model presents wonderful reliabilities and strong predictive abilities with R2 =0.858, =0.822, =0.813, =0.840, =0.807, =0.814, CCC=0.893, respectively. The derived model can be used to predict the binding abilities of unknown chemicals and may help to design novel molecules with better AR affinity activity.

Abstract OT1-02-02: A phase 1, first-in-human, multi-part study of RAD140, an oral nonsteroidal selective androgen receptor modulator, in postmenopausal women with hormone receptor positive breast cancer

Abstract Background: Hormone receptor-positive (HR+) breast cancer accounts for about 75% of breast cancer cases. Despite initial response to ER-targeted therapies, subsequent tumor progression remains an important clinical problem, highlighting the need for new therapies with activity in endocrine-resistant tumors. The androgen receptor (AR) is expressed in up to 90% of ER+ breast cancers, and until the 1970s, breast cancer was commonly treated with androgens with single-agent response rates ranging from 20% to 25%. However, androgen-based therapy for breast cancer declined due to lack of tissue selectivity, potential for aromatization to estrogen, and the emergence of ER-targeted agents such as tamoxifen. RAD140 is an oral nonsteroidal selective androgen receptor modulator (SARM) that cannot be converted to estrogen by aromatase. RAD140 has high AR affinity and target selectivity, demonstrating marked tissue-selective AR agonist activity comparable to natural androgens in breast cancer cells, but lacking agonist activity in prostate cancer cells. Preclinical efficacy studies in multiple in vivo and in vitro models of AR+/ER+ breast cancer demonstrate potent anti-tumor activity of RAD140 as a single agent and in combination with a CDK4/6 inhibitor. This first-in-human study will evaluate the safety, tolerability, pharmacokinetics (PK) and clinical activity of RAD140 in patients with HR+ breast cancer. Trial Design and Specific Aims: This is a Phase I, open-label dose escalation and safety expansion study of RAD140 in postmenopausal patients (pts) with advanced HR+ breast cancer for whom no standard therapy is available. During dose escalation (Part A), pts are assigned sequentially to escalating doses of RAD140 using a standard 3+3 design to establish a maximum tolerated dose (MTD) and/or recommended dose (RD) based on safety, PK and preliminary clinical activity. The Safety Expansion (Part B) will further evaluate the safety, tolerability and clinical activity of the RD. Eligibility Criteria: Pts must be post-menopausal females ≥18 years old with locally advanced or metastatic ER+/HER2- (Part A) or ER+/AR+/HER2- (Part B) breast cancer and ECOG 0 or 1. Part A pts must not be eligible for standard therapy. Pts in Part B must have had at least 1 line of prior systemic therapy in the metastatic setting and at least 6 months of prior endocrine therapy in the metastatic setting and progressed on the most recent endocrine therapy. Measurable disease by RECIST 1.1 is also required for enrollment in Part B. Statistical Methods: Descriptive statistics (including mean, standard deviation, median for continuous variables; frequency counts and percentages for categorical variables) will be presented by dose. Plasma or serum PK parameters for RAD140 will be estimated using non-compartmental methods. Present Accrual and Target Accrual: The study will enroll up to 40 pts, including up to approximately 24 pts enrolled in cohorts of 3 to 6 in Part A, and another 15 pts enrolled in Part B. As of June 2018, 11 pts have enrolled at 5 sites. (NCT03088527) Citation Format: Hamilton E, Vidula N, Ma C, LoRusso P, Saeh J, Reichert V, Yu Z, Annett M, Weitzman A, Hattersly G, O'Neill A, Weise A. A phase 1, first-in-human, multi-part study of RAD140, an oral nonsteroidal selective androgen receptor modulator, in postmenopausal women with hormone receptor positive breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT1-02-02.

Theranostic Pt(IV) Conjugate with Target Selectivity for Androgen Receptor.

It is difficult to diagnose and treat castration-resistant prostate cancer (CRPC) which occurs due to the overexpression of androgen receptor (AR). Because there is a high level of AR in CRPC, we designed and prepared three Pt(IV)-based prodrugs targeting AR. Among them, compound 3, a three-in-one hybrid (an AR binding ligand, a cisplatin unit, and a coumarin moiety), was found to display satisfactory AR binding affinity and antagonist activity against androgen receptor, which could also be effectively internalized and visualized in LNCaP (AR+) cells. Due to its AR affinity, 3 selectively accumulated in greater quantities in LNCaP (AR+) cells than in PC-3 (AR-) cells. Moreover, compound 3 exhibited excellent anticancer activity superior to cisplatin.These results highlight the targeting theranostic application of Pt(IV) prodrugs.

NAD(P)H-quinone oxidoreductase 1 silencing aggravates hormone-induced prostatic hyperplasia in mice.

NAD(P)H-quinone oxidoreductase 1 (NQO1) is a highly inducible flavoprotein known to involve in various cellular defence mechanisms. In this study, we explored whether NQO1 deletion affects hormone-induced prostatic hyperplasia. Testosterone propionate (3mg/kg, IP) was injected into wild-type (WT) and NOQ1 knockout C57BL/6 mice (NQO1-/- ) for 14 consecutive days, and the samples were collected for biological and histochemical studies. The testosterone-treated NQO1-/- showed about 140% higher prostate weight than the testosterone-treated WT, with enhanced connective tissue and hyperplastic glands formations. However, increased dihydrotestosterone level after testosterone treatment was not significantly different between the WT and NQO1-/- . In contrast, the enhanced nuclear expression of proliferating cell nuclear antigen in NQO1-/- prostate confirmed aggravated prostatic hyperplasia in NQO1-/- . Moreover, the expression of heat shock protein (HSP) 90-α was markedly increased in the NQO1-/- , and this was supported by increased testosterone-induced nuclear androgen receptor expression in NQO1-silenced LNCaP cells. Testosterone-induced prostate-specific antigen expression was not reversed in NOQ1-silenced cells after finasteride treatment. Although the exact role of NQO1 in prostatic hyperplasia remains unclear, the hyperplasia exacerbation due to NQO1 deletion might be independent of type 2 5α-reductase and might be related to enhanced androgen receptor affinity due to enhanced HSP90-α expression.

Seasonal expression of P450c17 and 5α-reductase-2 in the scented gland of male muskrats (Ondatra zibethicus)

Cytochrome P450 17A1 (P450c17) is the key enzyme required for the production of androgenic sex steroids by converting progestogens to androgens. 5α-reductases are enzymes that convert testosterone (T) to dihydrotestosterone (DHT), which has a greater affinity for androgen receptors (AR) and stronger action than T. Our previous studies revealed that the scented glands of male muskrats expressed AR during the breeding and nonbreeding seasons. To further seek evidence of the activities of androgens in scented glands, the expression patterns of P450c17 and 5α-reductase 2 were investigated in the scented glands of male muskrats during the breeding and nonbreeding seasons. The weight and size of scented glands in the breeding season were significantly higher than those of the nonbreeding season. Immunohistochemical data showed that P450c17 and 5α-reductase 2 were presented in the glandular cells and epithelial cells of scented glands in both the seasons. The protein and mRNA expression of P450c17 and 5α-reductase 2 were significantly higher in the scented gland during the breeding season than those during the nonbreeding season. In addition, the levels of DHT and T in the scented gland were remarkably higher during the breeding season. Taken together, these results suggested that the scented glands of male muskrats were capable of locally synthesizing T and DHT, and T and DHT might play an important role in the scented glandular function via an autocrine or paracrine manner.

Abstract 1236: Novel androgen receptor inhibitors in triple negative breast cancer

Abstract Triple negative breast cancer (TNBC), which lacks expression of hormone receptors and human epidermal growth factor receptor 2, has the worst prognosis of all breast cancer subtypes, due to inherent chemo-resistance and a lack of therapeutic targets. A subset of TNBC has been shown to express androgen receptor (AR) but despite promising pre-clinical data, clinical trials evaluating the use of approved anti-androgens (bicalutamide, enzalutamide) in AR-positive TNBC has shown modest efficacy to date. In prostate cancer, bicalutamide binds to AR with low affinity and in the presence of AR gene amplification or mutation, can exhibit partial agonist activity leading to resistance. In order to increase affinity for AR and to avoid AR antagonist to agonist conversion synthesized 7-substituted umbelliferones (UMB) derivatives with a distinct scaffold modified from available AR antagonists (Kandil et al Bioorganic &amp; Medicinal Chemistry Letters, 2016). These agents exhibited inhibitory activity in human prostate cancer cells lines at sub-micro molar level, a 50-fold and 30-fold improvement over bicalutamide and enzalutamide, respectively. We hypothesized that these novel AR antagonists would be effective in inhibiting the growth of AR-positive TNBC cells. Methods: TNBC AR negative mesenchymal MDA-MB-231 (as control) and AR positive MDA-MB-231 cells were utilized for determination of the efficacy of the UMB derivatives. For proliferation assays, viability of the cells was monitored over a period of 72 hours with redox dye Cell Titer-Blue. Standard Western blotting techniques were used for protein detection. For apoptosis analysis, standard flow cytometry reagents, FITC labelled Annexin V and Propidium Iodine(PI) mix were utilized. Results: UMB derivatives decreased the expression of AR in AR-positive MDA-MB-453 in a dose dependent manner. UMB derivatives, at micro Molar concentration decreased cell proliferation of AR-positive and interestingly AR-negative cell lines by 20 to 50%, also in a dose dependent manner. UMB derivatives induced apoptosis in both cell lines. Interestingly, UMB derivatives induced a change from a mesenchymal to epithelial phenotype in AR-negative MDA-MB-231 cells, which was confirmed by decreased expression of vimentin and other mesenchymal markers. Conclusions: Novel UMB derivatives inhibit growth and cause apoptosis in TNBC cells and induce mesenchymal-to-epithelial transition in an AR-negative mesenchymal TNBC cell line. Targeting AR with novel AR antagonists seem to be a promising therapeutic approach for AR-positive TNBC and further evaluation of AR antagonists in AR-negative mesenchymal TNBC is warranted. Citation Format: Saswati Bhattacharya, Yuanqi Cai, Steven Kurina, Pamela Westmark, Benjamin Hokanson, Matthew Anderson, Ruth O’Regan. Novel androgen receptor inhibitors in triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1236. doi:10.1158/1538-7445.AM2017-1236

Circulating AR copy number and outcome to enzalutamide in patients with metastatic castration-resistant prostate cancer after docetaxel.

e16583Background: Enzalutamide is a new anti-androgen with a great affinity for androgen receptor (AR). We aimed at identifying circulating AR copy number (CN) gain as non-invasive biomarker for ou...

Structure–activity relationship studies of miniproteins targeting the androgen receptor–coactivator interaction

Miniproteins featuring a stable α-helical motif allow exploring point mutations in and around FXXLF motifs to improve androgen receptor affinity.

Anti-Tumor Effects and Pharmacokinetics of S-40542, a Novel Non-Steroidal Anti-Androgen, in Mice.

The current study was undertaken to explore novel anti-androgens. We investigated a series of tetrahydroquinoline compounds and identified 1-(8-nitro-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]quinolin-4-yl)ethane-1,2-diol (S-40542). Affinity for androgen receptor of S-40542 was evaluated in receptor binding assay. Effects of repeated treatment with S-40542 and bicalutamide on prostate weight were examined in mice subcutaneously treated for 14days. Efficacy of S-40542 and bicalutamide against prostate cancer was evaluated in an androgen-dependent prostate cancer xenograft model using KUCaP-2 cell line. Plasma concentrations of these agents in mice after oral and subcutaneous administration were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) system. S-40542 displayed twofold higher affinity to androgen receptor than bicalutamide in vitro. Subcutaneous repeated administration of S-40542 (10-100 mg/kg) significantly reduced the prostate weight. Oral repeated treatment with S-40542 (30, 100 mg/kg) for 28 days significantly suppressed growth of KUCaP-2 tumor. Similar administration of bicalutamide also exerted significantly anti-tumor effect in the model. The serum prostate-specific antigen level was little influenced by the S-40542 treatment, while significantly decreased by bicalutamide. Oral treatment with S-40542 resulted in a dose-dependent elevation of the plasma concentration, and its Cmax and AUC were much lower than those of bicalutamide. The pharmacokinetic study showed that this agent had relatively short plasma half-life and low oral bioavailability. S-40542 as well as bicalutamide has shown as an anti-androgen by reducing the prostate weight of mice. Repeated oral treatment with S-40542 was shown to significantly suppress tumor growth in the KUCaP-2 xenograft model.

Steroid derivatives as pure antagonists of the androgen receptor

BackgroundWhile the androgens of testicular origin (representing about 50% of total androgens in men over 50 years) can be completely eliminated by surgical or medical castration with GnRH (gonadotropin-releasing hormone) agonists or antagonists, the antiandrogens currently available as blockers of androgen binding to the androgen receptor (AR), namely bicalutamide (BICA), flutamide (FLU) and nilutamide have too weak affinity to completely neutralize the other 50% of androgens made locally from dehydroepiandrosterone (DHEA) in the prostate cancer tissue by the mechanisms of intracrinology. Materials and methodsSeries of steroid derivatives having pure and potent antagonistic activity on the human and rodent AR were synthesized. Assays of AR binding and activity in carcinoma mouse Shionogi and human LNCaP cells as well as in vivo bioavailability measurements and in vivo prostate weight assays in the rat were used. ResultsThe chosen lead steroidal compound, namely EM-5854, has a 3.7-fold higher affinity than BICA for the human AR while EM-5855, an important metabolite of EM-5854, has a 94-fold higher affinity for the human AR compared to BICA. EM-5854 and EM-5855 are 14 times more potent than BICA in inhibiting androgen (R1881)-stimulated prostatic specific antigen (PSA) secretion in human prostatic carcinoma LNCaP cells in vitro. MDV3100 has a potency comparable to bicalutamide in these assays. Depending upon the oral formulation, EM-5854 is 5- to 10-times more potent than BICA to inhibit dihydrotestosterone (DHT)-stimulated ventral prostatic weight in vivo in the rat while MDV3100 has lower activity than BICA in this in vivo model. These data are supported by respective 40-fold and 105-fold higher potencies of EM-5854 and EM-5855 compared to BICA to inhibit cell proliferation in the androgen-sensitive Shionogi carcinoma cell model. ConclusionsAlthough the present preclinical results data need evaluation in clinical trials in men, combination of the data obtained in vitro in human LNCaP cells as indicator of potency in the human prostate and the data on metabolism evaluated in vivo on ventral prostate weight in the rat, could suggest the possibility of a 70- to 140-fold higher potency of EM-5854 compared to bicalutamide (Casodex) for the treatment of prostate cancer in men.