Discovery and therapeutic promise of selective androgen receptor modulators

The disordering effect of SARMs on a biomembrane model

From medicine to sport, selective androgen receptor modulators (SARMs) have represented promising applications. The ability of SARMs to selectively interact with the androgen receptor (AR) indicates that this kind of molecule can interfere with numerous physiological and pathological processes controlled by the AR regulatory mechanism. However, critical concerns in relation to safety and potential side effects of SARMs remain under discussion and investigation. SARMs, being hydrophobic/organic compounds, can be subjected to hydrophobic interactions. In this perspective, we hypothesize that SARMs interact with lipid membranes, producing significant physical and chemical changes that could be associated with several effects that SARMs represent in biological systems. In this context, the effect of SARMs on lipid membranes mediated by non-specific interactions is little explored. Here, we report significant information related to the changes that ostarine, ligandrol, andarine, and cardarine produce in the thermodynamic properties of a lipid biomembrane model. Physical changes and chemical interactions of the systems were investigated by differential scanning calorimetry (DSC), dynamic light scattering (DLS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and theoretical calculations implementing density functional theory (DFT). We demonstrate that ostarine, ligandrol, andarine, and cardarine can strongly interact with a lipid biomembrane model composed of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), and accordingly, these molecules can be incorporated into the polar/hydrophobic regions of the lipid bilayer. By employing theoretical calculations, we gained insights into the possible electrostatic interactions between SARMs and phospholipid molecules, enhancing our understanding of the driving forces behind the interactions of SARMs with lipid membranes. Overall, this investigation provides relevant knowledge related to the biophysical-chemical effects that SARMs produce in biomembrane models and could be of practical reference for promising applications of SARMs in medicine and sport.

Contaminants in Dietary Supplements: Toxicity, Doping Risk, and Current Regulation

Athletes, both amateur and professional, often resort to the consumption of nutritional supplements without professional supervision and without being aware of the risks they may entail. We conducted an exhaustive literature search to determine the most common substances found as contaminants in dietary supplements. For each substance, we analyzed its mechanism of action, clinical indication, health risk, and putative use as doping agent. In addition, we evaluated the current regulation of these supplements. Contamination of nutritional supplements (accidental or intentional), especially with steroids and stimulants, is a hazardous situation. The prolonged consumption of these products without being aware of their composition can cause serious health risks and, in the case of professional athletes, a possible sanction for doping.

Evidence of ostarine cross-contamination via sweat in 2 athletes sharing the same neoprene hamstring sleeves. An original situation of drug transfer where the anti-doping rule violation was suspended by the sport authorities

The presence of ostarine, a selective androgen receptor modulator (SARM) in an athlete's sample constitutes one of the most frequent anti-doping rules violation. It is possible to challenge this violation but it is the athlete who has to demonstrate he / she is innocent. The conditions to evidence no fault or negligence are mostly based on 2 points: 1. the athlete or his/her legal representative must present verified circumstances of contamination and the source of contamination must be identified; and 2. there must be verified claims by the athlete about the fact that he / she did not knowingly take the prohibited substance, i.e. that the violation was not intentional. During a 2-weeks period, a male athlete tested two times positive for ostarine in urine (<0.1 ng/ml) and he challenged these results. His hair and nail tests returned negative (LOQ at 0.5 pg/mg). He admitted using two neoprene hamstring sleeves of another athlete who confessed abusing ostarine. This was confirmed in his hair (190 pg/mg), his fingernail clippings (780 pg/mg) and his toenail clippings (45 pg/mg). To document the presence of ostarine in the hamstring sleeves and therefore possible drug transfer, the hamstring sleeves were analysed. Ostarine was identified in 12 different selected pieces (about 1 g) of the sleeves at concentrations ranging from 3 to 142 pg/g. Sport authorities (USADA) agreed that the most likely source of contamination was the hamstring sleeves, thus confirming the scenario of drug transfer and gave the athlete a no fault.

Investigation of in vitro generated metabolites of LGD-4033, a selective androgen receptor modulator, in homogenized camel liver for anti-doping applications

RATIONALE

The use of selective androgen receptor modulators (SARM) in sports is prohibited by the World Anti-Doping Agency (WADA) due to their potential as performance-enhancing drugs, offering an unfair advantage. LGD-4033 is a SARM known for its similarities to anabolic steroids and can be easily purchased online, leading to increased availability and misuse. Adverse analytical findings have revealed the presence of SARMs in dietary supplements. Although LGD-4033 misuse has been reported in human sports over the years, concerns also arise regarding its illicit use in animal sports, including camel racing. Although various studies have investigated the metabolism of LGD-4033 in humans, horse, and other species, there is limited research specifically dedicated to racing camels.

METHODS

This study focuses on the in vitro metabolism of LGD-4033 in homogenized camel liver using liquid chromatography-high-resolution mass spectrometry (LC-HRMS) to identify and characterize the metabolites.

RESULTS

The findings indicated the presence of 12 phase I metabolites and 1 phase II metabolite. Hydroxylation was responsible for the formation of the main phase I metabolites that were identified. A glucuronic acid conjugate of the parent drug was observed in this study, but no sulfonic acid conjugate was found. The possible chemical structures of these metabolites, along with their fragmentation patterns, were identified using MS.

CONCLUSIONS

These findings provide valuable insights into the metabolism of LGD-4033 in camels and aid in the development of effective doping control methods for the detection of SARMs in camel racing.

A combined treatment with selective androgen and estrogen receptor modulators prevents bone loss in orchiectomized rats

PURPOSE

Enobosarm (EN), a selective androgen receptor modulator and raloxifene (RAL), a selective estrogen receptor modulator, have been shown to improve bone tissue in osteoporotic males. The present study evaluated the effects of a combination therapy of EN and RAL on bone properties in orchiectomized rats compared to the respective single treatments.

METHODS

Eight-month-old male Sprague-Dawley rats were either left intact (Non-Orx) or orchiectomized (Orx). The Orx rats were divided into four groups (n = 15 each): 1) Orx, 2) EN treatment (Orx + EN), 3) RAL treatment (Orx + RAL), 4) combined treatment (Orx + EN + RAL). EN and RAL (0.4 mg and 7 mg/kg body weight/day) were applied immediately after Orx with a soy-free pelleted diet for up to 18 weeks. The lumbar spine and femora were examined by micro-CT, biomechanical, histomorphological, ashing, and gene expression analyses.

RESULTS

EN exhibited an anabolic effect on bone, improving some of its parameters in Orx rats, but did not affect biomechanical properties. RAL exhibited antiresorptive activity, maintaining the biomechanical and trabecular parameters of Orx rats at the levels of Non-Orx rats. EN + RAL exerted a stronger effect than the single treatments, improving most of the bone parameters. Liver weight increased after all treatments; the kidney, prostate, and levator ani muscle weights increased after EN and EN + RAL treatments. BW was reduced due to a decreased food intake in the Orx + RAL group and due a reduced visceral fat weight in the Orx + EN + RAL group.

CONCLUSION

The EN + RAL treatment appeared to be promising in preventing male osteoporosis, but given the observed side effects on liver, kidney, and prostate weights, it requires further investigation.

The forensic response after an adverse analytical finding (doping) involving a selective androgen receptor modulator (SARM) in human athlete

Selective androgen receptor modulators (SARMs) are a class of drugs presenting identical anabolic properties to anabolic steroids in addition to marked reduced androgenic effects. These drugs have emerged in the doping area within the early 2000's. Ligandrol, ostarine, RAD-140 and andarine are the most popular agents belonging to this class. According to the world anti-doping agency (WADA) prohibited list, SARMs are prohibited at all times (i.e. in and out-of-competition) and are listed under the section S1.2 (other anabolic agents). The compilation of the WADA testing figures reports from 2015 to 2019 has indicated a regular increase of adverse analytical findings (AAF) due to SARMs, particularly with ostarine and ligandrol. The implementation of highly sensitive chromatographic anti-doping analyses has induced high-profile challenges of anti-doping rules violations as athletes have claimed in numerous occasions that contamination was the reason for their AAF. Since the early 2000's, it has been accepted by the Court of Arbitration for Sports (CAS) in Lausanne (Switzerland) that, under some specific circumstances, unusual explanations can be provided to the Panel to explain an AAF. This was the open door for forensic investigations, as it is done in criminal Courts. A forensic approach can include testing for SARMs in food, drinks, but mostly in dietary supplements. As most anti-doping rules violations are only known several weeks after urine collection, this biological matrix is seldom use for further tests, despite the fact that most SARMs can be detected for several weeks in urine. Luckily, hair or nail testing can be a complement to document the claim of the athlete but of course, it cannot be considered as an alternative to urinalysis. This is because a negative hair or nail result cannot exclude the use of the detected drug and cannot overrule the urine result. To date, all methods for SARMs identification in various matrices involve liquid chromatography coupled to tandem mass spectrometry or high-resolution mass spectrometry. The aim of this paper is to review the scientific literature on the analytical possibilities of testing SARMs in dietary supplements, urine and hair or nail clippings after an AAF to document the claims of an athlete or his/her legal team.

Peroxisome Proliferator-Activated Receptor Delta Agonist (PPAR- δ) and Selective Androgen Receptor Modulator (SARM) Abuse: Clinical, Analytical and Biological Data in a Case Involving a Poisonous Combination of GW1516 (Cardarine) and MK2866 (Ostarine)

A 43-year-old male, sport coach, presented him-self at the Emergency unit of a local hospital for epigastric pain, myalgia pain and severe headache. He claimed having used for some days a combination of GW1516 (cardarine), a peroxisome proliferator-activated receptor delta agonist (PPAR- δ) and MK2866 (ostarine), a selective androgen receptor modulator (SARM) to gain skeletal muscles. Cytolysis with marked increase of alanine aminotransferase or ALT (up to 922 UI/L) and aspartate aminotransferase or AST (up to 2558 UI/L) and massive rhabdomyolysis with elevated creatine phosphokinase or CPK (up to 86435 UI/L) were the main unusual biochemistry parameters. Using a specific liquid chromatography coupled to tandem mass spectrometry method, cardarine and ostarine tested positive in blood at 403 and 1 ng/mL, respectively. In urine, due to extensive metabolism, the parent GW1516 was not identified, while ostarine was at 88 ng/mL. Finally, both drugs were identified in hair (2 cm in length, brown in colour), at 146 and 1105 pg/mg for cardarine and ostarine, respectively. This clearly demonstrates repetitive abuse over the last 2 months. Asthenia was persistent for 2 weeks and 6 weeks after the admission, the subject fully recovered.

Performance- and image-enhancing drug use in the community: use prevalence, user demographics and the potential role of wastewater-based epidemiology

Performance- and image-enhancing drug (PIED) misuse is a significant public health issue. Currently, seizure data, surveys, anti-doping testing, and needle service provider data are used to estimate PIED use in populations. These methods are time consuming, single point-in-time measurements that often consist of small sample sizes and do not truly capture PIED prevalence. Wastewater-based epidemiology (WBE) has been used globally to assess and monitor licit and illicit drug consumption within the general community. This method can objectively cover large populations as well as specific subpopulations (gyms, music festivals, prisons), and has potential as a complementary monitoring method for PIED use. Information obtained through WBE could be used to aid public health authorities in developing targeted prevention and education programmes. Research on PIED analysis in wastewater is limited and presents a significant gap in the literature. The focus is on anabolic steroids, and one steroid alternative currently growing in popularity; selective androgenic receptor modulators. This encompasses medical uses, addiction, prevalence, user typology, and associated public health implications. An overview of WBE is described including its benefits, limitations and potential as a monitoring method for PIED use. A summary of previous work in this field is presented. Finally, we summarise gaps in the literature, future perspectives, and recommendations for monitoring PIEDs in wastewater.

Simultaneous detection of different chemical classes of selective androgen receptor modulators in urine by liquid chromatography-mass spectrometry-based techniques

Analytical procedures to detect the misuse of selective androgen receptor modulators in human urine, targeting either the parent drugs and/or their main metabolites, were developed and validated. In detail, 19 target compounds belonging to 9 different chemical classes were considered: arylpropionamide (i.e., andarine (S4), ostarine (S22), S1, S6, S9 and S23), diarylhydantoin (i.e., GLPG0492), indole (i.e., LY2452473, GSK2881078), isoquinoline-carbonyle (i.e., PF-02620414), phenyl-oxadiazole (i.e., RAD140), pyrrolidinyl-benzonitrile (i.e., LGD4033), quinolinone (i.e., LGD2226, LGD3303), steroidal (i.e., Cl-4AS-1, MK0773 and TFM-4AS-1), and tropanol (i.e., AC-262536 and ACP105) derivatives. The metabolites of the target compounds considered were enzymatically synthesized by using human liver microsomes. Sample pre-treatment included enzymatic hydrolysis followed by liquid-liquid extraction at neutral pH. The instrumental analysis was performed by ultra-high-performance liquid chromatography coupled to either high- or low-resolution mass spectrometry. Validation was performed according to the ISO 17025 and the World Anti-Doping Agency guidelines. The analyses carried out on negative samples confirmed the method's selectivity, not showing any significant interferences at the retention times of the analytes of interest. Detection capability was determined in the range of 0.1-1.0 ng/mL for the screening procedure and 0.2-1.0 ng/mL for the confirmation procedure (except for GLPG0492 and GSK2881078). The recovery was greater than 80 % for all analytes, and the matrix effect was smaller than 35 %. The method also matched the criteria of the World Anti-Doping Agency in terms of repeatability of the relative retention times (CV% < 1.0) and of the relative abundances of the selected ion transitions (performed only in the case of triple quadrupole, CV% < 15), ensuring the correct identification of all the analytes considered. Urine samples containing andarine, ostarine, or LGD4033 were used to confirm the actual applicability of the selected analytical strategies. All target compounds (parent drugs and their main metabolites) were detected and correctly identified.

Drug Repurposing for Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most aggressive type of breast cancer which presents a high rate of relapse, metastasis, and mortality. Nowadays, the absence of approved specific targeted therapies to eradicate TNBC remains one of the main challenges in clinical practice. Drug discovery is a long and costly process that can be dramatically improved by drug repurposing, which identifies new uses for existing drugs, both approved and investigational. Drug repositioning benefits from improvements in computational methods related to chemoinformatics, genomics, and systems biology. To the best of our knowledge, we propose a novel and inclusive classification of those approaches whereby drug repurposing can be achieved in silico: structure-based, transcriptional signatures-based, biological networks-based, and data-mining-based drug repositioning. This review specially emphasizes the most relevant research, both at preclinical and clinical settings, aimed at repurposing pre-existing drugs to treat TNBC on the basis of molecular mechanisms and signaling pathways such as androgen receptor, adrenergic receptor, STAT3, nitric oxide synthase, or AXL. Finally, because of the ability and relevance of cancer stem cells (CSCs) to drive tumor aggressiveness and poor clinical outcome, we also focus on those molecules repurposed to specifically target this cell population to tackle recurrence and metastases associated with the progression of TNBC.

Dietary Supplement and Food Contaminations and Their Implications for Doping Controls

A narrative review with an overall aim of indicating the current state of knowledge and the relevance concerning food and supplement contamination and/or adulteration with doping agents and the respective implications for sports drug testing is presented. The identification of a doping agent (or its metabolite) in sports drug testing samples constitutes a violation of the anti-doping rules defined by the World Anti-Doping Agency. Reasons for such Adverse Analytical Findings (AAFs) include the intentional misuse of performance-enhancing/banned drugs; however, also the scenario of inadvertent administrations of doping agents was proven in the past, caused by, amongst others, the ingestion of contaminated dietary supplements, drugs, or food. Even though controversial positions concerning the effectiveness of dietary supplements in healthy subjects exist, they are frequently used by athletes, anticipating positive effects on health, recovery, and performance. However, most supplement users are unaware of the fact that the administration of such products can be associated with unforeseeable health risks and AAFs in sports. In particular anabolic androgenic steroids (AAS) and stimulants have been frequently found as undeclared ingredients of dietary supplements, either as a result of cross-contaminations due to substandard manufacturing practices and missing quality controls or an intentional admixture to increase the effectiveness of the preparations. Cross-contaminations were also found to affect therapeutic drug preparations. While the sensitivity of assays employed to test pharmaceuticals for impurities is in accordance with good manufacturing practice guidelines allowing to exclude any physiological effects, minute trace amounts of contaminating compounds can still result in positive doping tests. In addition, food was found to be a potential source of unintentional doping, the most prominent example being meat tainted with the anabolic agent clenbuterol. The athletes’ compliance with anti-doping rules is frequently tested by routine doping controls. Different measures including offers of topical information and education of the athletes as well as the maintenance of databases summarizing low- or high-risk supplements are important cornerstones in preventing unintentional anti-doping rule violations. Further, the collection of additional analytical data has been shown to allow for supporting result management processes.

Neural network activation similarity: a new measure to assist decision making in chemical toxicology

Deep learning neural networks, constructed for the prediction of chemical binding at 79 pharmacologically important human biological targets, show extremely high performance on test data (accuracy 92.2 ± 4.2%, MCC 0.814 ± 0.093 and ROC-AUC 0.96 ± 0.04). A new molecular similarity measure, Neural Network Activation Similarity, has been developed, based on signal propagation through the network. This is complementary to standard Tanimoto similarity, and the combined use increases confidence in the computer's prediction of activity for new chemicals by providing a greater understanding of the underlying justification. The in silico prediction of these human molecular initiating events is central to the future of chemical safety risk assessment and improves the efficiency of safety decision making.

Selective Androgen Receptor Modulators: Current Knowledge and Clinical Applications

INTRODUCTION

Selective androgen receptor modulators (SARMs) differentially bind to androgen receptors depending on each SARM's chemical structure. As a result, SARMs result in anabolic cellular activity while avoiding many of the side effects of currently available anabolic steroids. SARMs have been studied in the treatment of breast cancer and cachexia and have also been used as performance-enhancing agents. Here, we evaluate and summarize the current literature on SARMs.

AIM

To present the background, mechanisms, current and potential clinical applications, as well as risks and benefits of SARMs.

METHODS

A literature review was performed in MEDLINE using the terms selective androgen receptor modulator, hypogonadism, cachexia, breast cancer, benign prostatic hyperplasia, libido, and lean muscle mass. Both basic research and clinical studies were included.

MAIN OUTCOME MEASURE

To complete a review of peer-reviewed literature.

RESULTS

Although there are currently no U.S. Food and Drug Agency-approved indications for SARMs, investigators are exploring the potential uses for these compounds. Basic research has focused on the pharmacokinetics and pharmacodynamics of these agents, demonstrating good availability with a paucity of drug interactions. Early clinical studies have demonstrated potential uses for SARMs in the treatment of cancer-related cachexia, benign prostatic hyperplasia (BPH), hypogonadism, and breast cancer, with positive results.

CONCLUSION

SARMs have numerous possible clinical applications, with promise for the safe use in the treatment of cachexia, BPH, hypogonadism, breast cancer, and prostate cancer. Solomon ZJ, Mirabal JR, Mazur DJ, et al. Selective Androgen Receptor Modulators: Current Knowledge and Clinical Applications. Sex Med Rev 2019;7:84-94.

Detection of SARMs in doping control analysis

The class of selective androgen receptor modulators (SARMs) has been the subject of intense and dedicated clinical research over the past two decades. Potential therapeutic applications of SARMs are manifold and focus particularly on the treatment of conditions manifesting in muscle loss such as general sarcopenia, cancer-associated cachexia, muscular dystrophy, etc. Consequently, based on the substantial muscle- and bone-anabolic properties of SARMs, these agents constitute substances with significant potential for misuse in sport and have therefore been added to the Word Anti-Doping Agency's (WADA's) Prohibited List in 2008. Since then, numerous adverse analytical findings have been reported for various different SARMs, which has underlined the importance of proactive and preventive anti-doping measures concerning emerging drugs such as these anabolic agents, which have evidently been misused in sport despite the fact that none of these SARMs has yet received full clinical approval. In this review, analytical data on SARMs generated in the context of research conducted for sports drug testing purposes are summarized and state-of-the-art test methods aiming at intact drugs as well as diagnostic urinary metabolites are discussed. Doping control analytical approaches predominantly rely on chromatography hyphenated to mass spectrometry, which have allowed for appropriately covering the considerable variety of pharmacophores present in SARMs such as the non-steroidal representatives ACP-105, BMS-564929, GLPG0492 (DT-200), LG-121071, LGD-2226, LGD-4033/VK 5211, ostarine/enobosarm, RAD-140, S-40503, etc. as well as steroidal compounds such as MK-0773 and YK-11.

Mass spectrometric studies on selective androgen receptor modulators (SARMs) using electron ionization and electrospray ionization/collision-induced dissociation

Selective androgen receptor modulators (SARMs) have been identified as a promising class of drug candidates potentially applicable to diverse pathological conditions commonly associated with significantly reduced muscle mass. Due to a suspected and meanwhile repeatedly proven misuse of SARMs in elite and amateur sport, sustaining constantly updated doping control analytical methods is critical for sports drug testing laboratories. These test methods predominantly utilize mass spectrometry-based instrumentations and, consequently, studies on the mass spectrometric behavior of new compounds and, where available, their metabolic products are vital for comprehensive doping controls. In this communication, the dissociation patterns of three new SARM drug candidates referred to as GSK2881078, PF-06260414, and TFM-4 AS-1 as observed under electron ionization as well as electrospray ionization/collision-induced dissociation are discussed. By means of high resolution/high accuracy tandem mass spectrometry employing quadrupole-orbitrap mass analyzers, information on precursor-product ion relationships and elemental compositions was obtained and subsequently utilized to suggest dissociation routes of the target compounds. This information can contribute to future studies concerning structure assignments of metabolites and accelerate the identification of related substances if distributed and/or illicitly used in the world of sport.

Mass spectrometric characterization of the selective androgen receptor modulator (SARM) YK-11 for doping control purposes

RATIONALE

Selective androgen receptor modulators (SARMs) represent an emerging class of therapeutics targeting inter alia conditions referred to as cachexia and sarcopenia. Due to their anabolic properties, the use of SARMs is prohibited in sports as regulated by the World Anti-Doping Agency (WADA), and doping control laboratories test for these anabolic agents in blood and urine. In order to accomplish and maintain comprehensive test methods, the characterization of new drug candidates is critical for efficient sports drug testing. Hence, in the present study the mass spectrometric properties of the SARM YK-11 were investigated.

METHODS

YK-11 was synthesized according to literature data and three different stable-isotope-labeled analogs were prepared to support the mass spectrometric studies. Using high-resolution/high-accuracy mass spectrometry following electrospray ionization as well as electron ionization, the dissociation pathways of YK-11 were investigated, and characteristic features of its (product ion) mass spectra were elucidated. These studies were flanked by density functional theory (DFT) computation providing information on proton affinities of selected functional groups of the analyte.

RESULTS AND CONCLUSIONS

The steroidal SARM YK-11 was found to readily protonate under ESI conditions followed by substantial in-source dissociation processes eliminating methanol, acetic acid methyl ester, and/or ketene. DFT computation yielded energetically favored structures of the protonated species resulting from the aforementioned elimination processes particularly following protonation of the steroidal D-ring substituent. Underlying dissociation pathways were suggested, supported by stable-isotope labeling of the analyte, and diagnostic product ions for the steroidal nucleus and the D-ring substituent were identified. Further, trimethylsilylated YK-11 and its deuterated analogs were subjected to electron ionization high-resolution/high-accuracy mass spectrometry, complementing the dataset characterizing this new SARM. The obtained fragment ions resulted primarily from A/B- and C/D-ring structures of the steroidal nucleus, thus supporting future studies e.g. concerning metabolic pathways of the substance. Copyright © 2017 John Wiley & Sons, Ltd.

Sex Differences in Muscle Wasting

With aging and other muscle wasting diseases, men and women undergo similar pathological changes in skeletal muscle: increased inflammation, enhanced oxidative stress, mitochondrial dysfunction, satellite cell senescence, elevated apoptosis and proteasome activity, and suppressed protein synthesis and myocyte regeneration. Decreased food intake and physical activity also indirectly contribute to muscle wasting. Sex hormones also play important roles in maintaining skeletal muscle homeostasis. Testosterone is a potent anabolic factor promoting muscle protein synthesis and muscular regeneration. Estrogens have a protective effect on skeletal muscle by attenuating inflammation; however, the mechanisms of estrogen action in skeletal muscle are less well characterized than those of testosterone. Age- and/or disease-induced alterations in sex hormones are major contributors to muscle wasting. Hence, men and women may respond differently to catabolic conditions because of their hormonal profiles. Here we review the similarities and differences between men and women with common wasting conditions including sarcopenia and cachexia due to cancer, end-stage renal disease/chronic kidney disease, liver disease, chronic heart failure, and chronic obstructive pulmonary disease based on the literature in clinical studies. In addition, the responses in men and women to the commonly used therapeutic agents and their efficacy to improve muscle mass and function are also reviewed.

Pushing estrogen receptor around in breast cancer

The estrogen receptor-α (herein called ER) is a nuclear sex steroid receptor (SSR) that is expressed in approximately 75% of breast cancers. Therapies that modulate ER action have substantially improved the survival of patients with ER-positive breast cancer, but resistance to treatment still remains a major clinical problem. Treating resistant breast cancer requires co-targeting of ER and alternate signalling pathways that contribute to resistance to improve the efficacy and benefit of currently available treatments. Emerging data have shown that other SSRs may regulate the sites at which ER binds to DNA in ways that can powerfully suppress the oncogenic activity of ER in breast cancer. This includes the progesterone receptor (PR) that was recently shown to reprogram the ER DNA binding landscape towards genes associated with a favourable outcome. Another attractive candidate is the androgen receptor (AR), which is expressed in the majority of breast cancers and inhibits growth of the normal breast and ER-positive tumours when activated by ligand. These findings have led to the initiation of breast cancer clinical trials evaluating therapies that selectively harness the ability of SSRs to 'push' ER towards anti-tumorigenic activity. Our review will focus on the established and emerging clinical evidence for activating PR or AR in ER-positive breast cancer to inhibit the tumour growth-promoting functions of ER.

Investigation of the selective androgen receptor modulators S1, S4 and S22 and their metabolites in equine plasma using high-resolution mass spectrometry

RATIONALE

Selective androgen receptor modulators (SARMs) are prohibited in sports due to their performance enhancing ability. It is important to investigate the metabolism to determine appropriate targets for doping control. This is the first study where the equine metabolites of SARMs S1, S4 (Andarine) and S22 (Ostarine) have been studied in plasma.

METHODS

Each SARM was administered to three horses as an intravenous bolus dose and plasma samples were collected. The samples were pretreated with protein precipitation using cold acetonitrile before separation by liquid chromatography. The mass spectrometric analysis was performed using negative electrospray, quadrupole time-of-flight mass spectrometry operated in MS(E) mode and triple-quadrupole mass spectrometry operated in selected reaction monitoring mode. For the quantification of SARM S1, a deuterated analogue was used as internal standard.

RESULTS

The numbers of observed metabolites were eight, nine and four for the SARMs S1, S4 and S22, respectively. The major metabolite was formed by the same metabolic reactions for all three SARMs, namely amide hydrolysis, hydroxylation and sulfonation. The values of the determined maximum plasma concentrations were in the range of 97-170 ng/mL for SARM S1, 95-115 ng/mL for SARM S4 and 92-147 ng/mL for SARM S22 and the compounds could be detected for 96 h, 12 h and 18 h, respectively.

CONCLUSIONS

The maximum plasma concentration of SARMs S1, S4 and S22 was measured in the first sample (5 min) after administration and they were eliminated fast from plasma. The proposed targets to be used in equine doping control are the parent compounds for all three SARMs, but with the metabolite yielding the highest response as a complementary target. Copyright © 2016 John Wiley & Sons, Ltd.

In vitro metabolism study of a black market product containing SARM LGD-4033

Anabolic agents are often used by athletes to enhance their performance. However, use of steroids leads to considerable side effects. Non-steroidal selective androgen receptor modulators (SARMs) are a novel class of substances that have not been approved so far but seem to have a more favourable anabolic/androgenic ratio than steroids and produce fewer side effects. Therefore the use of SARMs has been prohibited since 2008 by the World Anti-Doping Agency (WADA). Several of these SARMs have been detected on the black market. Metabolism studies are essential to identify the best urinary markers to ensure effective control of emerging substances by doping control laboratories. As black market products often contain non-pharmaceutical-grade substances, alternatives for human excretion studies are needed to elucidate the metabolism. A black market product labelled to contain the SARM LGD-4033 was purchased over the Internet. Purity verification of the black market product led to the detection of LGD-4033, without other contaminants. Human liver microsomes and S9 liver fractions were used to perform phase I and phase II (glucuronidation) metabolism studies. The samples of the in vitro metabolism studies were analyzed by gas chromatography-(tandem) mass spectrometry (GC-MS(/MS)), liquid chromatography-high resolution-tandem mass spectrometry (LC-(HR)MS/MS). LC-HRMS product ion scans allowed to identify typical fragment ions for the parent compound and to further determine metabolite structures. In total five metabolites were detected, all modified in the pyrrolidine ring of LGD-4033. The metabolic modifications ranged from hydroxylation combined with keto-formation (M1) or cleavage of the pyrrolidine ring (M2), hydroxylation and methylation (M3/M4) and dihydroxylation (M5). The parent compound and M2 were also detected as glucuronide-conjugates. Copyright © 2016 John Wiley & Sons, Ltd.

Identification of a Novel Coregulator, SH3YL1, That Interacts With the Androgen Receptor N-Terminus

Nuclear receptor (NR)-mediated transcriptional activity is a dynamic process that is regulated by the binding of ligands that induce distinct conformational changes in the NR. These structural alterations lead to the differential recruitment of coregulators (coactivators or corepressors) that control the expression of NR-regulated genes. Here, we show that a stretch of proline residues located within the N-terminus of androgen receptor (AR) is a bona fide coregulator binding surface, the disruption of which reduces the androgen-dependent proliferation and migration of prostate cancer (PCa) cells. Using T7 phage display, we identified a novel AR-interacting protein, Src homology 3 (SH3)-domain containing, Ysc84-like 1 (SH3YL1), whose interaction with the receptor is dependent upon this polyproline domain. As with mutations within the AR polyproline domain, knockdown of SH3YL1 attenuated androgen-mediated cell growth and migration. RNA expression analysis revealed that SH3YL1 was required for the induction of a subset of AR-modulated genes. Notable was the observation that ubinuclein 1 (UBN1), a key member of a histone H3.3 chaperone complex, was a transcriptional target of the AR/SH3YL1 complex, correlated with aggressive PCa in patients, and was necessary for the maximal androgen-mediated proliferation and migration of PCa cells. Collectively, these data highlight the importance of an amino-terminal activation domain, its associated coregulator, and downstream transcriptional targets in regulating cellular processes of pathological importance in PCa.

Characterization of a non-approved selective androgen receptor modulator drug candidate sold via the Internet and identification of in vitro generated phase-I metabolites for human sports drug testing

RATIONALE

Potentially performance-enhancing agents, particularly anabolic agents, are advertised and distributed by Internet-based suppliers to a substantial extent. Among these anabolic agents, a substance referred to as LGD-4033 has been made available, comprising the core structure of a class of selective androgen receptor modulators (SARMs).

METHODS

In order to provide comprehensive analytical data for doping controls, the substance was obtained and characterized by nuclear magnetic resonance spectroscopy (NMR) and liquid chromatography/electrospray ionization high resolution/high accuracy tandem mass spectrometry (LC/ESI-HRMS). Following the identification of 4-(2-(2,2,2-trifluoro-1-hydroxyethyl)pyrrolidin-1-yl)-2-(trifluoromethyl)benzonitrile, the substance was subjected to in vitro metabolism studies employing human liver microsomes and Cunninghamella elegans (C. elegans) preparations as well as electrochemical metabolism simulations.

RESULTS

By means of LC/ESI-HRMS, five main phase-I metabolites were identified as products of liver microsomal preparations including three monohydroxylated and two bishydroxylated species. The two most abundant metabolites (one mono- and one bishydroxylated product) were structurally confirmed by LC/ESI-HRMS and NMR. Comparing the metabolic conversion of 4-(2-(2,2,2-trifluoro-1-hydroxyethyl)pyrrolidin-1-yl)-2-(trifluoromethyl)benzonitrile observed in human liver microsomes with C. elegans and electrochemically derived metabolites, one monohydroxylated product was found to be predominantly formed in all three methodologies.

CONCLUSIONS

The implementation of the intact SARM-like compound and its presumed urinary phase-I metabolites into routine doping controls is suggested to expand and complement existing sports drug testing methods.

Recent discoveries and developments of androgen receptor based therapy for prostate cancer

The main focus of this review is to discuss the discoveries and developments of various therapies for prostate cancer.

The athlete biological passport: ticket to a fair Commonwealth Games

In summer 2014, the world watched as Glasgow hosted the 2014 Commonwealth Games and athletes pushed the boundaries of human performance. Sport has developed into a multi-billion pound industry leading to the development of a 'win at any cost' mentality in some individuals. The abuse of performance-enhancing drugs has developed into a sophisticated arms race between those unfairly enhancing performance and those wishing to preserve the dignity of sport and the health of the competitors. The challenge for the Commonwealth games organising committee was to ensure that competition remained fair and that athletes were kept safe. The athlete biological passport is a system implemented by the World Anti-Doping Agency directed towards enhancing the identification of those athletes accountable for the misuse of performance-enhancing substances. This article exemplifies which drugs are currently being exploited and how the athlete biological passport has evolved to improve their detection.

Evaluation of Resettin® on serum hormone levels in sedentary males

Background

Comparisons of hormones such as dihydrotestosterone (DHT), estradiol (E2), and testosterone indicate their impact on metabolism and body composition. While less is known regarding DHT and E2, testosterone is an androgenic metabolic hormone capable of positively regulating a variety of anabolic and androgenic processes in the body. Accordingly, it has been postulated that the age-related reduction in serum testosterone levels leads to reductions in lean muscle mass, bone mineral density, and other physical conditions that impair physical performance and decrease quality of life. Preliminary studies suggest that key ingredients found in Resettin®/MyTosterone™, a natural supplement containing the carotenoid astaxanthin from Haematococcus pluvialis and Saw Palmetto berry lipid extract from Serenoa repens, could positively impact testosterone levels. To investigate the clinical efficacy of Resettin®, the serum profiles of testosterone, E2 and DHT in healthy sedentary males before and after Resettin® treatment were evaluated in a randomized, placebo controlled clinical trial.

Method

Twenty healthy, sedentary men between the ages of 21 and 70 were randomized into either an 800 mg/day or 1200 mg/day Resettin®/MyTosterone™ treatment group or lecithin, which was used as the placebo. After a 14-day treatment period, there was a 14-day washout period. After the wash-out period, participants were crossed over within their respective group to either Resettin®/MyTosterone™ or the lecithin placebo for 14 days.

Results

After 14 days, participants receiving 800 mg per day of Resettin® had significantly reduced baseline-subtracted serum DHT levels in comparison to the placebo control group. While after 14 days, participants receiving 1200 mg per day of Resettin® had significantly reduced baseline-subtracted serum DHT and E2 levels in comparison to the placebo control group. Moreover, participants receiving 1200 mg per day of Resettin® experienced a 38% increase in serum testosterone levels in comparison to the placebo control group, but the effect did not reach statistical significance.

Conclusion

Although additional studies will be required to evaluate how Resettin® may promote proper testosterone regulation, these findings indicate that Resettin® can favorably influence serum hormone profiles in men.

Emerging therapeutic targets for osteoporosis treatment

INTRODUCTION

To date, osteoporosis still remains a major public health burden especially for the aging populations. Over the last few decades treatments for osteoporosis have largely focused on anti-resorptive agents represented by bisphosphonates and estrogen therapy that dominated the market. Unsatisfactory efficacy, non-specificity and long-term safety of current therapies necessitate the need for new targets effectively preventing and treating of osteoporosis.

AREAS COVERED

This review expatiates on the mechanism of osteoporosis occurrence and bone remodeling cycle in detail. New targets of antiresorptive and anabolic agents based on the functions of osteoblasts and osteoclasts as well as associated signaling pathways are outlined.

EXPERT OPINION

Advanced understanding in the fields of bone remodeling, functions of osteoblasts, osteoclasts and osteocytes associated with osteoporosis occurrence offers the emerging bone-resorptive or bone-formative targets. Currently, molecules involving RANK-RANKL-OPG system and Wnt/β-catenin signaling pathway act as the most promising targets.

Nuclear receptors and their selective pharmacologic modulators

Nuclear receptors are ligand-activated transcription factors and include the receptors for steroid hormones, lipophilic vitamins, sterols, and bile acids. These receptors serve as targets for development of myriad drugs that target a range of disorders. Classically defined ligands that bind to the ligand-binding domain of nuclear receptors, whether they are endogenous or synthetic, either activate receptor activity (agonists) or block activation (antagonists) and due to the ability to alter activity of the receptors are often termed receptor "modulators." The complex pharmacology of nuclear receptors has provided a class of ligands distinct from these simple modulators where ligands display agonist/partial agonist/antagonist function in a tissue or gene selective manner. This class of ligands is defined as selective modulators. Here, we review the development and pharmacology of a range of selective nuclear receptor modulators.

The androgen receptor and its use in biological assays: looking toward effect-based testing and its applications

Steroid abuse is a growing problem among amateur and professional athletes. Because of an inundation of newly and illegally synthesized steroids with minor structural modifications and other designer steroid receptor modulators, there is a need to develop new methods of detection which do not require prior knowledge of the abused steroid structure. The number of designer steroids currently being abused is unknown because detection methods in general are only identifying substances with a known structure. The detection of doping is moving away from merely checking for exposure to prohibited substance toward detecting an effect of prohibited substances, as biological assays can do. Cell-based biological assays are the next generation of assays which should be utilized by antidoping laboratories; they can detect androgenic anabolic steroid and other human androgen receptor (hAR) ligand presence without knowledge of their structure and assess the relative biological activity of these compounds. This review summarizes the hAR and its action and discusses its relevance to sports doping and its use in biological assays.

Alanine aminotransferase regulation by androgens in non-hepatic tissues

PURPOSE

Alanine amino-transferases (ALTs) play a crucial role in drug development as a surrogate marker of liver injury where elevations in serum ALT activity are used to diagnose drug-induced liver damage. Two ALT isoforms have been characterized with disparate but overlapping tissue expression. ALT1 is primarily expressed in live; ALT2 is found in muscle and prostate tissues. We investigate ALT gene expression in diverse rodent tissues following administration of the steroidal androgen receptor (AR) agonist dihydrotestosterone and a novel tissue selective nonsteroidal agonist S-23.

METHODS

Putative AR regulation of ALT expression was determined in silico by an orthologous promoter androgen response element (ARE) search. Regulation was evaluated by transient transfection of ALT promoter region constructs and qRT-PCR experiments in cultured cells and in tissues following androgen administration.

RESULTS

Several putative AREs were found in the proximal promoter regions of ALT1 and ALT2. AREs in ALT2 but not ALT1 were capable of AR-mediated transcription. ALT2 expression was affected by castration and androgen administration in muscle and prostate but not liver tissues.

CONCLUSIONS

Androgen action in non-hepatic tissues, as opposed to xenobiotic toxicity alone, may contribute to increases in serum ALT activity following androgen administration.

Androgen receptor as a therapeutic target

Androgens function as sex hormone primarily via activation of a single androgen receptor (AR, or NR3C4). AR is an important therapeutic target for the treatment of diseases such as hypogonadism and prostate cancer. AR ligands of different chemical structures and/or pharmacological properties are widely used for these therapeutic applications, and all of the AR ligands currently available for therapy modulate AR function via direct binding to the ligand-binding pocket (LBP) of the receptor. In the past ten years, our understanding of AR structure and molecular mechanism of action has progressed extensively, which has encouraged the rapid development of newer generation of AR ligands, particularly tissue-selective AR ligands. With improved tissue selectivity, future generations of AR ligands are expected to greatly expand the therapeutic applications of this class of drugs. This review will provide an overview of the common therapeutic applications of currently available AR ligands, and discussion of the major challenges as well as novel therapeutic strategies proposed for future drug development.

Doping and musculoskeletal system: short-term and long-lasting effects of doping agents

Doping is a problem that has plagued the world of competition and sports for ages. Even before the dawn of Olympic history in ancient Greece, competitors have looked for artificial means to improve athletic performance. Since ancient times, athletes have attempted to gain an unfair competitive advantage through the use of doping substances. A Prohibited List of doping substances and methods banned in sports is published yearly by the World Anti-Doping Agency. Among the substances included are steroidal and peptide hormones and their modulators, stimulants, glucocorticosteroids, β₂-agonists, diuretics and masking agents, narcotics, and cannabinoids. Blood doping, tampering, infusions, and gene doping are examples of prohibited methods indicated on the List. Apart from the unethical aspect of doping, as it abrogates fair-play's principle, it is extremely important to consider the hazards it presents to the health and well-being of athletes. The referred negative effects for the athlete's health have to do, on the one hand, by the high doses of the performance-enhancing agents and on the other hand, by the relentless, superhuman strict training that the elite or amateur athletes put their muscles, bones, and joints. The purpose of this article is to highlight the early and the long-lasting consequences of the doping abuse on bone and muscle metabolism.