A New Avenue toward Androgen Receptor Pan-antagonists: C2 Sterically Hindered Substitution of Hydroxy-propanamides

Synthesis of Indole- and Benzofuran-Based Benzylic Sulfones by Palladium-Catalyzed Sulfonylation of ortho-Iodoaryl Allenes

A highly efficient palladium-catalyzed domino coupling reaction of ortho-iodoaryl allene with sodium sulfonates under mild conditions is described. This novel method provides a practical protocol to access diverse indole- and benzofuran-containing sulfones by simultaneous construction of C(sp2)-C(sp2) bond and a C(sp3)-S bonds in one pot. The salient features of this transformation include simple operations, broad substrate scope, and good functional group tolerance.

Aminosulfonylation of Rhodium Carbene via Ylide Formation and 1,4-Sulfonyl Rearrangement

We report here the use of pyridin-2-yl benzenesulfonates as sulfonylation reagents in a difunctionalization reaction based on oxy-pyridinium ylide chemistry, providing an effective protocol for the installation of both a sulfonyl group and a pyridone moiety into one molecule. Density functional theory (DFT) calculations disclose that the reaction process might proceed through sequential metal-bound ylide formation, keto-enol tautomerism, and the migratory rearrangement of the sulfonyl group.

Toward Bicalutamide Analogues with High Structural Diversity Using Catalytic Asymmetric Oxohydroxylation

A catalytic enantioselective synthesis of bicalutamide derivatives with promising potentials in prostate cancer treatment has been disclosed. The key intermediates, α-hydroxy-β-keto esters, were efficiently constructed through cinchoninium-mediated asymmetric oxohydroxylation of easily accessible alkenes with potassium permanganate. Good yields and high levels of asymmetric induction are achieved. This method provides a new synthetic route to bicalutamide analogues with high structural diversity, which will beneficially support subsequent structure-activity relationship studies and boost prostate cancer drug development.

Growing Utilization of Radical Chemistry in the Synthesis of Pharmaceuticals

Our current unhealthy lifestyle and the exponential surge in the population getting affected by a variety of diseases have made pharmaceuticals or drugs an imperative part of life, making the development of innovative strategies for drug discovery or the introduction of refined, cost-effective and modern technologies for the synthesis of clinically used drugs, a need of the hour. Ever since their discovery, free radicals and radical cations or anions as reactive intermediates have captivated the chemists, resulting in an exceptional utilization of these moieties throughout the field of chemical synthesis, owing to their unprecedented and widespread reactivity. Sticking with the idea of not judging the book by its cover, despite the conventional thought process of radicals being unstable and difficult to control entities, scientists and academicians around the globe have done an appreciable amount of work utilizing both persistent as well as transient radicals for a variety of organic transformations, exemplifying them with the synthesis of significant biologically active pharmaceutical ingredients. This review truly accounts for the organic radical transformations including radical addition, radical cascade cyclization, radical/radical cross-coupling, coupling with metal-complexes and radical cations coupling with nucleophiles, that offers fascinating and unconventional approaches towards the construction of intricate structural frameworks of marketed APIs with high atom- and step-economy; complementing the otherwise employed traditional methods. This tutorial review presents a comprehensive package of diverse methods utilized for radical generation, featuring their reactivity to form critical bonds in pharmaceutical total synthesis or in building key starting materials or intermediates of their synthetic journey, acknowledging their excellence, downsides and underlying mechanisms, which are otherwise poorly highlighted in the literature. Despite great achievements over the past few decades in this area, many challenges and obstacles are yet to be unraveled to shorten the distance between the academics and the industry, which are all discussed in summary and outlook.

Discovery of , a First-in-Class and Orally Bioavailable PROTAC Degrader of the Androgen Receptor Targeting N-Terminal Domain for the Treatment of Prostate Cancer

We report small molecular PROTAC compounds targeting the androgen receptor N-terminal domain (AR-NTD), which were obtained by tethering AR-NTD antagonists and different classes of E3 ligase ligands through chemical linkers. A representative compound, BWA-522, effectively induces degradation of both AR-FL and AR-V7 and is more potent than the corresponding antagonist against prostate cancer (PC) cells in vitro. We have shown that the degradation of AR-FL and AR-V7 proteins by BWA-522 can suppress the expression of AR downstream proteins and induce PC cell apoptosis. BWA-522 achieves 40.5% oral bioavailability in mice and 69.3% in beagle dogs. In a LNCaP xenograft model study, BWA-522 was also proved to be an efficacious PROTAC degrader, resulting in 76% tumor growth inhibition after oral administration of a dose of 60 mg/kg. This study indicates that BWA-522 is a promising AR-NTD PROTAC for the treatment of AR-FL- and AR-V7-dependent tumors.

TBAI-Mediated Cyclization and Methylsulfonylation of Propargylic Amides with Dimethyl Sulfite

A tetramethylammonium iodide (TBAI)-mediated cyclization and methylsulfonylation of propargylic amides enabled by dimethyl sulfite as a SO₂ surrogate and methyl source have been developed. The transition metal-free and oxidant-free reaction provides a practical and efficient approach for the selective synthesis of methylsulfonyl oxazoles in moderate to excellent yields with good functional group compatibility.

Proteolysis-targeting chimeras in biotherapeutics: Current trends and future applications

The success of inhibitor-based therapeutics is largely constrained by the acquisition of therapeutic resistance, which is partially driven by the undruggable proteome. The emergence of proteolysis targeting chimera (PROTAC) technology, designed for degrading proteins involved in specific biological processes, might provide a novel framework for solving the above constraint. A heterobifunctional PROTAC molecule could structurally connect an E3 ubiquitin ligase ligand with a protein of interest (POI)-binding ligand by chemical linkers. Such technology would result in the degradation of the targeted protein via the ubiquitin-proteasome system (UPS), opening up a novel way of selectively inhibiting undruggable proteins. Herein, we will highlight the advantages of PROTAC technology and summarize the current understanding of the potential mechanisms involved in biotherapeutics, with a particular focus on its application and development where therapeutic benefits over classical small-molecule inhibitors have been achieved. Finally, we discuss how this technology can contribute to developing biotherapeutic drugs, such as antivirals against infectious diseases, for use in clinical practices.

Therapeutic Strategies to Target the Androgen Receptor

The androgen receptor (AR) plays a key role in the maintenance of muscle and bone and the support of male sexual-related functions, as well as in the progression of prostate cancer. Accordingly, AR-targeted therapies have been developed for the treatment of related human diseases and conditions. AR agonists are an important class of drugs in the treatment of bone loss and muscle atrophy. AR antagonists have also been developed for the treatment of prostate cancer, including metastatic castration-resistant prostate cancer (mCRPC). Additionally, selective AR degraders (SARDs) have been reported. More recently, heterobifunctional degrader molecules of AR have been developed, and four such compounds are now in clinical development for the treatment of human prostate cancer. This review attempts to summarize the different types of compounds designed to target AR and the current frontiers of research on this important therapeutic target.

Metal- and base-free tandem sulfonylation/cyclization of 1,5-dienes with aryldiazonium salts via the insertion of sulfur dioxide

A metal- and base-free 5-endo-trig sulfonylative cyclization between 1,5-dienes, aryldiazonium salts and SO₂ (from SOgen) is presented. This method could successfully produce sulfonylated pyrrolin-2-ones in one pot with excellent regioselectivity and good-to-excellent yields. This strategy features mild reaction conditions and broad substrate scope. Moreover, a scale-up reaction and three synthetic applications demonstrate the practicality of this method. Lastly, control experiments indicate that the 5-endo-trig sulfonylative cyclization may proceed in a radical pathway.

A new metal- and base-free method for synthesizing sulfonylated pyrrolin-2-ones from 1,5-dienes, aryldiazonium salts and SO₂ is presented. This transformation features mild reaction conditions and broad substrate scope.

Selective 1,4-arylsulfonation of 1,3-enynes via photoredox/nickel dual catalysis

A photoredox/nickel-catalyzed selective 1,4-arylsulfonation of 1,3-enynes to access structurally diverse sulfone-containing allenes has been established with low catalyst loading.

Expeditious and Efficient ortho-Selective Trifluoromethane-sulfonylation of Arylhydroxylamines

A metal- and oxidant-free, practical and efficient method for the synthesis of highly versatile and synthetically useful ortho-trifluoromethanesulfonylated anilines from arylhydroxylamines and trifluoromethanesulfinic chloride was developed. This rapid transformation proceeded smoothly with good yields and excellent ortho-selectivity in the absence of any metals or ligands. Mechanistically, the reaction comprised a noncanonical O-trifluoromethanesulfinylation of the arylhydroxylamine, and the subsequent [2,3]-sigmatropic rearrangement to afford ortho-trifluoromethanesulfonylated aniline derivatives. The practical application of this reaction was demonstrated by further conversion into a series of functional molecules under different reaction conditions.

Copper-Catalyzed N-Directed Distal C(sp3)-H Sulfonylation and Thiolation with Sulfinate Salts

We herein report a selective and catalytic C(sp³)-H functionalization approach to access amines bearing organo-sulfonyl and organo-thiol groups. This reaction proceeds through a cascade process of N-radical formation, alkyl radical formation via 1,5-HAT, and C-S bond formation, thereby offering a series of functionalized amines. This method could enable primary, secondary, and tertiary C(sp³)-H sulfonylation and thiolation and also exhibits good functional group tolerance.

Strategies toward Discovery of Potent and Orally Bioavailable Proteolysis Targeting Chimera Degraders of Androgen Receptor for the Treatment of Prostate Cancer

Proteolysis targeting chimera (PROTAC) small-molecule degraders have emerged as a promising new type of therapeutic agents, but the design of PROTAC degraders with excellent oral pharmacokinetics is a major challenge. In this study, we present our strategies toward the discovery of highly potent PROTAC degraders of androgen receptor (AR) with excellent oral pharmacokinetics. Employing thalidomide to recruit cereblon/cullin 4A E3 ligase and through the rigidification of the linker, we discovered highly potent AR degraders with good oral pharmacokinetic properties in mice with ARD-2128 being the best compound. ARD-2128 achieves 67% oral bioavailability in mice, effectively reduces AR protein and suppresses AR-regulated genes in tumor tissues with oral administration, leading to the effective inhibition of tumor growth in mice without signs of toxicity. This study supports the development of an orally active PROTAC AR degrader for the treatment of prostate cancer and provides insights and guidance into the design of orally active PROTAC degraders.

Copper-Mediated Cross-Coupling of Diazo Compounds with Sulfinates

A copper-mediated cross-coupling reaction between a diazo compound and a sodium alkane(arene)sulfinate gives a sulfone as the product. This reaction proceeds under mild conditions and features excellent functional group compatibility. A wide range of sodium alkane(arene)sulfinates were successfully applied in this chemistry. Mechanistic studies revealed that the overall reaction efficiency of the sulfinates was in line with their nucleophilicity in this reaction.

Copper-Catalyzed Chloro-Arylsulfonylation of Styrene Derivatives via the Insertion of Sulfur Dioxide

A copper-catalyzed four-component chloro-arylsulfonylation of styrene derivatives with aryldiazonium tetrafluoroborates, lithium chloride, and ex-situ generated sulfur dioxide (from SOgen) is presented. This sulfonylation features good functional group compatibility, mild reaction conditions, excellent regioselectivity, and good yields. The robustness and potential of this method have also been successfully demonstrated by a gram-scale reaction. Based on experimental study, a radical-involved mechanism is proposed for the transformation.

Synthesis, biological evaluation and X-ray analysis of bicalutamide sulfoxide analogues for the potential treatment of prostate cancer

The androgen receptor (AR) is a pivotal target for the treatment of prostate cancer (PC) even when the disease progresses toward androgen-independent or castration-resistant forms. In this study, a series of sulfoxide derivatives were prepared and their antiproliferative activity evaluated in vitro against four different human prostate cancer cell lines (22Rv1, DU-145, LNCaP and VCap). Bicalutamide and enzalutamide were used as positive controls. Compound 28 displayed significant enhancement in anticancer activity across the four PC cell lines with IC₅₀ = 9.09 - 31.11 µM compared to the positive controls: bicalutamide (IC₅₀ = 45.20 -51.61 µM) and enzalutamide (IC₅₀ = 11.47 - 53.04 µM). Sulfoxide derivatives of bicalutamide were prepared efficiently from the corresponding sulfides using only one equivalent of mCPBA, limiting the reaction time to 15-30 min and maintaining the temperature at 0 °C. Interestingly, three pairs of sulfoxide diastereomers were separated and NMR comparison of their diastereotopic methylene (CH₂) group is presented. X-ray diffraction crystal structure analysis provided relative configuration assignment at the chiral sulfur and carbon centres. Molecular modelling study of the four diastereoisomers of compound 28 is described.

Photosensitizer-free synthesis of β-keto sulfones via visible-light-induced oxysulfonylation of alkenes with sulfonic acids

A practical and environment-friendly methodology for the construction of β-keto sulfones through visible-light induced direct oxysulfonylation of alkenes with sulfonic acids at ambient temperature under open-air conditions was developed. Most importantly, the reaction proceeded smoothly without the addition of any photocatalyst or strong oxidant, ultimately minimizing the production of chemical waste.

Recent Advances of Sulfonylation Reactions in Water

BACKGROUND

The sulfonyl groups are general structural moieties present in agrochemicals, pharmaceuticals, and natural products. Recently, many efforts have been focused on developing efficient procedures for preparation of organic sulfones.

MATERIALS AND METHODS

Water, a proton source, is considered one of the most ideal and promising solvents in organic synthesis for its easy availability, low cost, nontoxic and nonflammable characteristics. From the green and sustainable point of view, more and more reactions are designed proceeding in water.

OBJECTIVE

The review focuses on recent advances of sulfonylation reactions proceeding in water. Sulfonylation reactions using sodium sulfinates, sulfonyl hydrazides, sulfinic acids, and sulfonyl chlorides as sulfonating agents were introduced in detail.

RESULTS AND DISCUSSION

In this review, sulfonylation reactions proceeding in water developed in recent four yields were presented. Sulfonylation reactions using water as solvent have attracted more and more attention because water is one of the most ideal and promising solvents in organic synthesis for its facile availability, low cost, nontoxic and nonflammable properties.

CONCLUSION

Numerous sulfonating agents such as sodium sulfinates, sulfonyl hydrazides, sulfinic acid, sulfonyl chlorides and disulfides are efficient for sulfonylation reactions which proceed in water.

Non-Steroidal Androgen Receptor Antagonists and Prostate Cancer: A Survey on Chemical Structures Binding this Fast-Mutating Target

The Androgen Receptor (AR) pathway plays a major role in both the pathogenesis and progression of prostate cancer. In particular, AR is chiefly involved in the development of Castration-Resistant Prostate Cancer (CRPC) as well as in the resistance to the secondgeneration AR antagonist enzalutamide, and to the selective inhibitor of cytochrome P450 17A1 (CYP17A1) abiraterone. Several small molecules acting as AR antagonists have been designed and developed so far, also as a result of the ability of cells expressing this molecular target to rapidly develop resistance and turn pure receptor antagonists into ineffective or event detrimental molecules. This review covers a survey of most promising classes of non-steroidal androgen receptor antagonists, also providing insights into their mechanism of action and efficacy in treating prostate cancer.

Non-nuclear AR Signaling in Prostate Cancer

Despite the key role played by androgen receptor (AR) in tumor cell aggressiveness and prostate cancer (PCa) progression, its function in the tumor microenvironment (TME) is still controversial. Increasing studies highlight the crucial role played by TME modulation in treatment outcome and tumor cell spreading. In this context, targeting specific constituents of the TME could be considered an alternative approach to classic treatments directed against cancer cells. Currently, androgen deprivation therapy (ADT) is a routinely adopted strategy in the management of PCa, with initial success, and consecutive fail. A possible justification to this is the fact that ADT aims to target all the transcription/translation-related activities of AR, which are typical of tumor epithelial cells. Less is still known about side effects of ADT on TME. Cancer Associated Fibroblasts (CAFs), for example, express a classic AR, mostly confined in the extra-nuclear portion of the cell. In CAFs ADT exerts a plethora of non-transcriptional effects, depending by the protein partner linked to AR, leading to cell migration, proliferation, and differentiation. In recent years, substantial progress in the structure-function relationships of AR, identification of its binding partners and function of protein complexes including AR have improved our knowledge of its signaling axis. Important AR non-genomic effects and lots of its cytoplasmatic binding partners have been described, pointing out a fine control of AR non-genomic pathways. Accordingly, new AR inhibitors have been designed and are currently under investigation. Prompt development of new approaches to target AR or block recruitment of its signaling effectors, or co-activators, is urgently needed. The present review takes an in-depth look at current literature, furnishing an exhaustive state-of-the-art overview of the non-genomic role of AR in PCa, with particular emphasis on its involvement in TME biology.

Electrochemical Alkoxysulfonylation Difunctionalization of Styrene Derivatives Using Sodium Sulfinates as Sulfonyl Sources

An eco-friendly method for the synthesis of β-alkoxy sulfones via electrochemical alkoxysulfonylation reaction of styrenes with sodium sulfinates as sulfonyl sources has been established. The reaction is conducted in an undivided cell at room temperature and tolerates a wide scope of styrenes, sodium sulfinates, and alcohols. The reaction does not need any chemical oxidants and transition-metal catalysts, which provides a new and green access to β-alkoxy sulfones.

Ligand Pathways in Nuclear Receptors

Nuclear receptors (NRs) are ligand-inducible transcription factors that play an essential role in a multitude of physiological processes as well as diseases, rendering them attractive drug targets. Crystal structures revealed the binding site of NRs to be buried in the core of the protein, with no obvious route for ligands to access this cavity. The process of ligand binding is known to be an often-neglected contributor to the efficacy of drug candidates and is thought to influence the selectivity and specificity of NRs. While experimental methods generally fail to highlight the dynamic processes of ligand access or egress on the atomistic scale, computational methods have provided fundamental insight into the pathways connecting the buried binding pocket to the surrounding environment. Methods based on molecular dynamics (MD) and Monte Carlo simulations have been applied to identify pathways and quantify their capability to transport ligands. Here, we systematically review findings of more than 20 years of research in the field, including the applied methodology and controversies. Further, we establish a unified nomenclature to describe the pathways with respect to their location relative to protein secondary structure elements and summarize findings relevant to drug design. Lastly, we discuss the effect of NR interaction partners such as coactivators and corepressors, as well as mutations on the pathways.

Nerve Growth Factor Induces Proliferation and Aggressiveness In Prostate Cancer Cells

Resistance to hormone therapy and disease progression is the major challenge in clinical management of prostate cancer (PC). Drugs currently used in PC therapy initially show a potent antitumor effects, but PC gradually develops resistance, relapses and spreads. Most patients who fail primary therapy and have recurrences eventually develop castration-resistant prostate cancer (CRPC), which is almost incurable. The nerve growth factor (NGF) acts on a variety of non-neuronal cells by activating the NGF tyrosine-kinase receptor, tropomyosin receptor kinase A (TrkA). NGF signaling is deregulated in PC. In androgen-dependent PC cells, TrkA mediates the proliferative action of NGF through its crosstalk with the androgen receptor (AR). Epithelial PC cells, however, acquire the ability to express NGF and TrkA, as the disease progresses, indicating a role for NGF/TrkA axis in PC progression and androgen-resistance. We here report that once activated by NGF, TrkA mediates proliferation, invasiveness and epithelial-mesenchymal transition (EMT) in various CRPC cells. NGF promotes organoid growth in 3D models of CRPC cells, and specific inhibition of TrkA impairs all these responses. Thus TrkA represents a new biomarker to target in CRPC.

Androgen Receptor-Directed Molecular Conjugates for Targeting Prostate Cancer

Due to its central role in the cellular biology of prostate cancer (PC), androgen receptor (AR) still remains an important therapeutic target for fighting this tumor. Several drugs targeting AR have been reported so far, and many new molecules are expected for the future. In spite of their antitumor efficacy, these drugs are not selective for malignant cells and are subjected to AR-mediated activation of drug resistance mechanisms that are responsible for several drawbacks, including systemic toxicity and disease recurrence and metastasis. Among the several strategies considered to overcome these drawbacks, very appealing appears the design of hybrid small-molecule conjugates targeting AR to drive drug action on receptor-positive PC cells. These compounds are designed around on an AR binder, which selectively engages AR with high potency, coupled with a moiety endowed with different pharmacological properties. In this review we focus on two classes of compounds: a) small-molecules and AR-ligand based conjugates that reduce AR expression, which allow down-regulation of AR levels by activating its proteasome-mediated degradation, and b) AR-ligand-based conjugates for targeting small-molecules, in which the AR binder tethers small-molecules, including conventional antitumor drugs (e.g., cisplatin, doxorubicin, histone deacetylase inhibitors, as well as photo-sensitizers) and selectively directs drug action toward receptor-positive PC cells.

Discovery of ARD-69 as a Highly Potent Proteolysis Targeting Chimera (PROTAC) Degrader of Androgen Receptor (AR) for the Treatment of Prostate Cancer

We report herein the discovery of highly potent PROTAC degraders of androgen receptor (AR), as exemplified by compound 34 (ARD-69). ARD-69 induces degradation of AR protein in AR-positive prostate cancer cell lines in a dose- and time-dependent manner. ARD-69 achieves DC₅₀ values of 0.86, 0.76, and 10.4 nM in LNCaP, VCaP, and 22Rv1 AR+ prostate cancer cell lines, respectively. ARD-69 is capable of reducing the AR protein level by >95% in these prostate cancer cell lines and effectively suppressing AR-regulated gene expression. ARD-69 potently inhibits cell growth in these AR-positive prostate cancer cell lines and is >100 times more potent than AR antagonists. A single dose of ARD-69 effectively reduces the level of AR protein in xenograft tumor tissue in mice. Further optimization of ARD-69 may ultimately lead to a new therapy for AR+, castration-resistant prostate cancer.

Current and potential targets for drug design in the androgen receptor pathway for prostate cancer

INTRODUCTION

Modulating the androgen axis by different agents has been one of the most successful therapeutic interventions in the field of prostate cancer therapy. Newer agents such as abiraterone and enzalutamide have been widely adapted and have contributed to an increase in the overall survival of prostate cancer patients. However, most of these patients will develop resistance to these agents and will need chemotherapy. Areas covered: In this review, this author discusses current agents which modulate the androgen axis, the mechanisms of resistance to these agents and investigative agents which are designed to bypass these mechanisms of resistance. Potential targets in the androgen axis and related biochemical pathways are, furthermore, identified. Expert opinion: Understanding the mechanism of resistance to these agents is crucial in developing third generation anti-androgen agents which can potentially contribute to the longevity of prostate cancer patients to a greater extent. Besides developing more potent agents, it is also important to formulate new strategies to resensitize patients to current anti-androgen agents by carefully sequencing chemotherapy regimens and abrogating genetic changes which are known to cause resistance to anti-androgens. Combinatorial approach with immunotherapy offers prospects which may yield better results and need to be thoroughly explored.

1,4-Substituted Triazoles as Nonsteroidal Anti-Androgens for Prostate Cancer Treatment

Prostate cancer (PC) is the fifth leading cause of cancer death in men, and the androgen receptor (AR) represents the primary target for PC treatment, even though the disease frequently progresses toward androgen-independent forms. Most of the commercially available nonsteroidal antiandrogens show a common scaffold consisting of two aromatic rings connected by a linear or a cyclic spacer. By taking advantage of a facile, one-pot click chemistry reaction, we report herein the preparation of a small library of novel 1,4-substituted triazoles with AR antagonistic activity. Biological and theoretical evaluation demonstrated that the introduction of the triazole core in the scaffold of nonsteroidal antiandrogens allowed the development of small molecules with improved overall AR-antagonist activity. In fact, compound 14d displayed promising in vitro antitumor activity toward three different prostate cancer cell lines and was able to induce 60% tumor growth inhibition of the CW22Rv1 in vivo xenograft model. These results represent a step toward the development of novel and improved AR antagonists.

Small Molecule Antagonists of the Nuclear Androgen Receptor for the Treatment of Castration-Resistant Prostate Cancer

After a high-throughput screening campaign identified thioether 1 as an antagonist of the nuclear androgen receptor, a zone model was developed for structure-activity relationship (SAR) purposes and analogues were synthesized and evaluated in a cell-based luciferase assay. A novel thioether isostere, cyclopropane (1S,2R)-27, showed the desired increased potency and structural properties (stereospecific SAR response, absence of a readily oxidized sulfur atom, low molecular weight, reduced number of flexible bonds and polar surface area, and drug-likeness score) in the prostate-specific antigen luciferase assay in C4-2-PSA-rl cells to qualify as a new lead structure for prostate cancer drug development.

Cross-talk between androgen receptor/filamin A and TrkA regulates neurite outgrowth in PC12 cells

Steroids and growth factors control neuronal development through their receptors under physiological and pathological conditions. We show that PC12 cells harbor endogenous androgen receptor (AR), whose inhibition or silencing strongly interferes with neuritogenesis stimulated by the nonaromatizable synthetic androgen R1881 or NGF. This implies a role for AR not only in androgen signaling, but also in NGF signaling. In turn, a pharmacological TrkA inhibitor interferes with NGF- or androgen-induced neuritogenesis. In addition, androgen or NGF triggers AR association with TrkA, TrkA interaction with PI3-K δ, and downstream activation of PI3-K δ and Rac in PC12 cells. Once associated with AR, filamin A (FlnA) contributes to androgen or NGF neuritogenesis, likely through its interaction with signaling effectors, such as Rac. This study thus identifies a previously unrecognized reciprocal cross-talk between AR and TrkA, which is controlled by β1 integrin. The contribution of FlnA/AR complex and PI3-K δ to neuronal differentiation by androgens and NGF is also novel. This is the first description of AR function in PC12 cells.

Progress in antiandrogen design targeting hormone binding pocket to circumvent mutation based resistance

Androgen receptor (AR) plays a critical role in the development and progression of prostate cancer (PCa). Current clinically used antiandrogens such as flutamide, bicalutamide, and newly approved enzalutamide mainly target the hormone binding pocket (HBP) of AR. However, over time, drug resistance invariably develops and switches these antiandrogens from antagonist to agonist of the AR. Accumulated evidence indicates that AR mutation is an important cause for the drug resistance. This review will give an overview of the mutation based resistance of the current clinically used antiandrogens and the rational drug design to overcome the resistance, provides a promising strategy for the development of the new generation of antiandrogens targeting HBP.

Overview on the complexity of androgen receptor-targeted therapy for prostate cancer

In the past decades, the field of prostate cancer (PCa) biology has developed exponentially and paralleled with that has been the growing interest in translation of laboratory findings into clinical practice. Based on overwhelming evidence of high impact research findings which support the underlying cause of insufficient drug efficacy in patients progressing on standard androgen deprivation therapy (ADT) is due to persistent activation of the androgen receptor (AR) signaling axis. Therefore, newer agents must be discovered especially because newer ADT such as abiraterone and enzalutamide are becoming ineffective due to rapid development of resistance to these agents. High-throughput technologies are generating massive and highly dimensional genetic variation data that has helped in developing a better understanding of the dynamic repertoire of AR and AR variants. Full length AR protein and its variants modulate a sophisticated regulatory system to orchestrate cellular responses. We partition this multicomponent review into subsections addressing the underlying mechanisms of resistance to recent therapeutics, positive and negative regulators of AR signaling cascade, and how SUMOylation modulates AR induced transcriptional activity. Experimentally verified findings obtained from cell culture and preclinical studies focusing on the potential of natural agents in inhibiting mRNA/protein levels of AR, nuclear accumulation and enhanced nuclear export of AR are also discussed. We also provide spotlight on molecular basis of enzalutamide resistance with an overview of the strategies opted to overcome such resistance. AR variants are comprehensively described and different mechanisms that regulate AR variant expression are also discussed. Reconceptualization of phenotype- and genotype-driven studies have convincingly revealed that drug induced resistance is a major stumbling block in standardization of therapy. Therefore, we summarize succinctly the knowledge of drug resistance especially to ADT and potential avenues to overcome such resistance for improving the treatment outcome of PCa patients.