Assays to Interrogate the Ability of Compounds to Inhibit the AF-2 or AF-1 Transactivation Domains of the Androgen Receptor

Optimization and calibration of 384-well kinetic Ca2+ mobilization assays for the human transient receptor potential cation channels TRPM8, TRPV1, and TRPA1

Development, optimization, and calibration of human transient receptor potential (TRP) channel Ca2+ mobilization assays for TRPM8, TRPV1, and TRPA1 are described. Heterologous expression of hTRPM8 in HEK293T cells was required for anti-TRPM8 antibody staining and TRPM8 agonist induced Ca2+ mobilization signals which were both used to optimize transfection efficiency. FLIPR Calcium 6 dye concentration, loading time, and TRPM8 transfected cell seeding density were optimized and a DMSO tolerance of ≤0.2 % was set. The resting baseline relative fluorescent unit (RFUs) signals of the TRPM8 Ca2+ mobilization assay exhibited substantial well-to-well variability, even though such differences were small relative to maximal agonist induced responses. Maximum RFU, cumulative RFU sum, or area under the curve values were extracted from Ca2+ mobilization kinetic data to plot curves and calculate EC50 and IC50 values. Fold over baseline (FOB) ratio data processing eliminated well-to-well differences in resting baseline signals, reduced error bars, improved curve fits and reduced 95 % confidence interval EC50 and IC50 ranges. FOB ratio data processing decreased variability and improved the precision of repeat measurements in single experimental sessions thereby reducing the minimum threshold difference in EC50 or IC50 values required to distinguish compound potencies. EC50 and IC50 values of TRPM8 agonists and antagonists determined in single experiments were strongly aligned to those from multiple independent experiments. Benchmark TRPM8, TRPV1, and TRPA1 EC50 and IC50 values were within the ranges previously reported for agonist and antagonist standards. The improved precision and accuracy of the TRP Ca2+ mobilization assays afforded by FOB ratio data processing enhances their utility for investigating structure activity relationships.

Hydropathic AF-2 variants in the androgen receptor gene among androgen insensitivity patients

BACKGROUND

Androgen insensitivity syndrome (AIS) is a common condition among individuals with differences of sexual development (DSD) and results from germline allelic variants in the androgen receptor (AR) gene. Understanding the phenotypic consequences of AR allelic variants that disrupt the activation function 2 (AF2) region is essential to grasping its clinical significance.

OBJECTIVES

This study aims to provide insights into the phenotypic characteristics and clinical impact of AR mutations affecting the AF2 region in AIS patients. We achieve this by reviewing reported AR variants in the AF2 region among individuals with AIS, including identifying a new phenotype associated with the c.2138T>C variant (p.Leu713Pro) in the AR gene.

MATERIALS AND METHODS

We comprehensively reviewed AR variants within the AF2 region reported in AIS and applied molecular dynamics simulations to assess the impact of the p.Leu713Pro variant on protein dynamics.

RESULTS

Our review of reported AR variants in the AF2 region revealed a spectrum of phenotypic outcomes in AIS patients. Molecular dynamics simulations indicated that the p.Leu713Pro variant significantly alters the local dynamics of the AR protein and disrupts the correlation and covariance between variables.

DISCUSSION

The diverse phenotypic presentations observed among individuals with AR variants in the AF2 region highlight the complexity of AIS. The altered protein dynamics resulting from the p.Leu713Pro variant further emphasize the importance of the AF2 region in AR function.

CONCLUSION

Our study provides valuable insights into AR mutations' phenotypic characteristics and clinical impact on the AF2 region in AIS. Moreover, the disruption of protein dynamics underscores the significance of the AF2 region in AR function and its role in the pathogenesis of AIS.

Characterization of allosteric modulators that disrupt androgen receptor co-activator protein-protein interactions to alter transactivation-Drug leads for metastatic castration resistant prostate cancer

Three series of compounds were prioritized from a high content screening campaign that identified molecules that blocked dihydrotestosterone (DHT) induced formation of Androgen Receptor (AR) protein-protein interactions (PPIs) with the Transcriptional Intermediary Factor 2 (TIF2) coactivator and also disrupted preformed AR-TIF2 PPI complexes; the hydrobenzo-oxazepins (S1), thiadiazol-5-piperidine-carboxamides (S2), and phenyl-methyl-indoles (S3). Compounds from these series inhibited AR PPIs with TIF2 and SRC-1, another p160 coactivator, in mammalian 2-hybrid assays and blocked transcriptional activation in reporter assays driven by full length AR or AR-V7 splice variants. Compounds inhibited the growth of five prostate cancer cell lines, with many exhibiting differential cytotoxicity towards AR positive cell lines. Representative compounds from the 3 series substantially reduced both endogenous and DHT-enhanced expression and secretion of the prostate specific antigen (PSA) cancer biomarker in the C4-2 castration resistant prostate cancer (CRPC) cell line. The comparatively weak activities of series compounds in the H3-DHT and/or TIF2 box 3 LXXLL-peptide binding assays to the recombinant ligand binding domain of AR suggest that direct antagonism at the orthosteric ligand binding site or AF-2 surface respectively are unlikely mechanisms of action. Cellular enhanced thermal stability assays (CETSA) indicated that compounds engaged AR and reduced the maximum efficacy and right shifted the EC50 of DHT-enhanced AR thermal stabilization consistent with the effects of negative allosteric modulators. Molecular docking of potent representative hits from each series to AR structures suggest that S1-1 and S2-6 engage a novel binding pocket (BP-1) adjacent to the orthosteric ligand binding site, while S3-11 occupies the AR binding function 3 (BF-3) allosteric pocket. Hit binding poses indicate spaces and residues adjacent to the BP-1 and BF-3 pockets that will be exploited in future medicinal chemistry optimization studies. Small molecule allosteric modulators that prevent/disrupt AR PPIs with coactivators like TIF2 to alter transcriptional activation in the presence of orthosteric agonists might evade the resistance mechanisms to existing prostate cancer drugs and provide novel starting points for medicinal chemistry lead optimization and future development into therapies for metastatic CRPC.

Current and emerging approaches to noncompetitive AR inhibition

The androgen receptor (AR) has been shown to be a key determinant in the pathogenesis of castration-resistant prostate cancer (CRPC). The current standard of care therapies targets the ligand-binding domain of the receptor and can afford improvements to life expectancy often only in the order of months before resistance occurs. Emerging preclinical and clinical compounds that inhibit receptor activity via differentiated mechanisms of action which are orthogonal to current antiandrogens show promise for overcoming treatment resistance. In this review, we present an authoritative summary of molecules that noncompetitively target the AR. Emerging small molecule strategies for targeting alternative domains of the AR represent a promising area of research that shows significant potential for future therapies. The overall quality of lead candidates in the area of noncompetitive AR inhibition is discussed, and it identifies the key chemotypes and associated properties which are likely to be, or are currently, positioned to be first in human applications.

Mild androgen insensitivity syndrome: the current landscape

OBJECTIVE

Mild Androgen Insensitivity (MAIS) belongs to the Androgen Insensitivity Syndrome (AIS) spectrum, an X-linked genetic disease that is the most common cause of differences in sex development (DSD). Unfortunately, AIS studies mainly focus on the partial and the complete phenotype, and the mild phenotype (MAIS) has been barely reported. Our purpose is to explore the MAIS facets, clinical features, and molecular aspects.

METHODS

We collected all reported MAIS cases in the medical literature and presented them based on the phenotype and the molecular diagnosis.

RESULTS

We identified 49 different AR mutations in 69 individuals in the literature. We compared the AR mutations presented in MAIS individuals with AR mutations previously reported in other AIS phenotypes (CAIS and PAIS) regarding the type, location, genotype-phenotype correlation, and functional studies.

CONCLUSION

This review provides a landscape of the mild phenotype of AIS. Most MAIS patients present with male infertility. Therefore, AR gene sequencing should be considered during male infertility investigation, even in males with typically male external genitalia. In addition, MAIS can be part of other medical conditions, such as X-linked spinal and bulbar muscular atrophy (Kennedy's disease).

The Role of Androgens and Androgen Receptor in Human Bladder Cancer

Bladder cancer (urothelial carcinoma) is one of the most frequently diagnosed neoplasms, with an estimated half a million new cases and 200,000 deaths per year worldwide. This pathology mainly affects men. Men have a higher risk (4:1) of developing bladder cancer than women. Cigarette smoking and exposure to chemicals such as aromatic amines, and aniline dyes have been established as risk factors for bladder cancer and may contribute to the sex disparity. Male internal genitalia, including the urothelium and prostate, are derived from urothelial sinus endoderm; both tissues express the androgen receptor (AR). Several investigations have shown evidence that the AR plays an important role in the initiation and development of different types of cancer including bladder cancer. In this article, we summarize the available data that help to explain the role of the AR in the development and progression of bladder cancer, as well as the therapies used for its treatment.