Androgen receptor (AR) aberrations in castration-resistant prostate cancer

Epitranscriptomic mechanisms of androgen signalling and prostate cancer

Prostate cancer (PCa) is the second most common cancer diagnosed in men. While radical prostatectomy and radiotherapy are often successful in treating localised disease, post-treatment recurrence is common. As the androgen receptor (AR) and androgen hormones play an essential role in prostate carcinogenesis and progression, androgen deprivation therapy (ADT) is often used to deprive PCa cells of the pro-proliferative effect of androgens. ADTs act by either blocking androgen biosynthesis (e.g. abiraterone) or blocking AR function (e.g. bicalutamide, enzalutamide, apalutamide, darolutamide). ADT is often effective in initially suppressing PCa growth and progression, yet emergence of castrate-resistant PCa and progression to neuroendocrine-like PCa following ADT are major clinical challenges. For this reason, there is an urgent need to identify novel approaches to modulate androgen signalling to impede PCa progression whilst also preventing or delaying therapy resistance. The mechanistic convergence of androgen and epitranscriptomic signalling offers a potential novel approach to treat PCa. The epitranscriptome involves covalent modifications of mRNA, notably, in the context of this review, the N(6)-methyladenosine (m6A) modification. m6A is involved in the regulation of mRNA splicing, stability, and translation, and has recently been shown to play a role in PCa and androgen signalling. The m6A modification is dynamically regulated by the METTL3-containing methyltransferase complex, and the FTO and ALKBH5 RNA demethylases. Given the need for novel approaches to treat PCa, there is significant interest in new therapies that target m6A that modulate AR expression and androgen signalling. This review critically summarises the potential benefit of such epitranscriptomic therapies for PCa patients.

Comprehensive data mining reveals RTK/RAS signaling pathway as a promoter of prostate cancer lineage plasticity through transcription factors and CNV

Prostate cancer lineage plasticity is a key driver in the transition to neuroendocrine prostate cancer (NEPC), and the RTK/RAS signaling pathway is a well-established cancer pathway. Nevertheless, the comprehensive link between the RTK/RAS signaling pathway and lineage plasticity has received limited investigation. In particular, the intricate regulatory network governing the interplay between RTK/RAS and lineage plasticity remains largely unexplored. The multi-omics data were clustered with the coefficient of argument and neighbor joining algorithm. Subsequently, the clustered results were analyzed utilizing the GSEA, gene sets related to stemness, multi-lineage state datasets, and canonical cancer pathway gene sets. Finally, a comprehensive exploration of the data based on the ssGSEA, WGCNA, GSEA, VIPER, prostate cancer scRNA-seq data, and the GPSAdb database was conducted. Among the six modules in the clustering results, there are 300 overlapping genes, including 3 previously unreported prostate cancer genes that were validated to be upregulated in prostate cancer through RT-qPCR. Function Module 6 shows a positive correlation with prostate cancer cell stemness, multi-lineage states, and the RTK/RAS signaling pathway. Additionally, the 19 leading-edge genes of the RTK/RAS signaling pathway promote prostate cancer lineage plasticity through a complex network of transcriptional regulation and copy number variations. In the transcriptional regulation network, TP63 and FOXO1 act as suppressors of prostate cancer lineage plasticity, whereas RORC exerts a promoting effect. This study provides a comprehensive perspective on the role of the RTK/RAS pathway in prostate cancer lineage plasticity and offers new clues for the treatment of NEPC.

Structure-Activity Relationship (SAR) Studies of Novel Monovalent AR/AR-V7 Dual Degraders with Potent Efficacy against Advanced Prostate Cancer

Androgen receptor (AR) has been extensively established as a potential therapeutic target for nearly all stages of prostate cancer (PCa). However, acquired resistance to AR-targeted drugs inevitably develops and severely limits their clinical efficacy. Particularly, there currently exists no efficient treatment for patients expressing the constitutively active AR splice variants, such as AR-V7. Herein, we report the structure-activity relationship studies of 55 N-heterocycle-substituted hydantoins, which identified the structural motifs required for AR/AR-V7 degradation. Among them, the most potent compound 27c exhibited selective AR/AR-V7 degradation over other hormone receptors and excellent antiproliferative activities in LNCaP and 22RV1 cells. RNA sequence analysis confirmed that 27c effectively suppressed transcriptional activity of the AR signaling pathway. Importantly, 27c demonstrated potent antitumor efficacy in an enzalutamide-resistant 22RV1 xenograft model. These results highlight the potential of 27c as a promising dual AR/AR-V7 degrader for overcoming drug resistance in advanced PCa expressing AR splice variants.

An Extracellular Matrix Overlay Model for Bioluminescence Microscopy to Measure Single-Cell Heterogeneous Responses to Antiandrogens in Prostate Cancer Cells

Prostate cancer (PCa) displays diverse intra-tumoral traits, impacting its progression and treatment outcomes. This study aimed to refine PCa cell culture conditions for dynamic monitoring of androgen receptor (AR) activity at the single-cell level. We introduced an extracellular matrix-Matrigel (ECM-M) culture model, enhancing cellular tracking during bioluminescence single-cell imaging while improving cell viability. ECM-M notably tripled the traceability of poorly adherent PCa cells, facilitating robust single-cell tracking, without impeding substrate permeability or AR response. This model effectively monitored AR modulation by antiandrogens across various PCa cell lines. Single-cell imaging unveiled heterogeneous antiandrogen responses within populations, correlating non-responsive cell proportions with drug IC50 values. Integrating ECM-M culture with the PSEBC-TSTA biosensor enabled precise characterization of ARi responsiveness within diverse cell populations. Our ECM-M model stands as a promising tool to assess heterogeneous single-cell treatment responses in cancer, offering insights to link drug responses to intracellular signaling dynamics. This approach enhances our comprehension of the nuanced and dynamic nature of PCa treatment responses.

Mechanism-centric regulatory network identifies NME2 and MYC programs as markers of Enzalutamide resistance in CRPC

Heterogeneous response to Enzalutamide, a second-generation androgen receptor signaling inhibitor, is a central problem in castration-resistant prostate cancer (CRPC) management. Genome-wide systems investigation of mechanisms that govern Enzalutamide resistance promise to elucidate markers of heterogeneous treatment response and salvage therapies for CRPC patients. Focusing on the de novo role of MYC as a marker of Enzalutamide resistance, here we reconstruct a CRPC-specific mechanism-centric regulatory network, connecting molecular pathways with their upstream transcriptional regulatory programs. Mining this network with signatures of Enzalutamide response identifies NME2 as an upstream regulatory partner of MYC in CRPC and demonstrates that NME2-MYC increased activities can predict patients at risk of resistance to Enzalutamide, independent of co-variates. Furthermore, our experimental investigations demonstrate that targeting MYC and its partner NME2 is beneficial in Enzalutamide-resistant conditions and could provide an effective strategy for patients at risk of Enzalutamide resistance and/or for patients who failed Enzalutamide treatment.

Photothermal therapy of papillary thyroid cancer tumor xenografts with targeted thyroid stimulating hormone receptor antibody functionalized multiwalled carbon nanotubes

Multiwalled carbon nanotubes (MWCNTs) are being widely investigated in multiple biomedical applications including, and not limited to, drug delivery, gene therapy, imaging, biosensing, and tissue engineering. Their large surface area and aspect ratio in addition to their unique structural, optical properties, and thermal conductivity also make them potent candidates for novel hyperthermia therapy. Here we introduce thyroid hormone stimulating receptor (TSHR) antibody–conjugate–MWCNT formulation as an enhanced tumor targeting and light-absorbing device for the photoablation of xenografted BCPAP papillary thyroid cancer tumors. To ensure successful photothermal tumor ablation, we determined three key criteria that needed to be addressed: (1) predictive pre-operational modeling; (2) real-time monitoring of the tumor ablation process; and (3) post-operational follow-up to assess the efficacy and ensure complete response with minimal side effects. A COMSOL-based model of spatial temperature distributions of MWCNTs upon selected laser irradiation of the tumor was prepared to accurately predict the internal tumor temperature. This modeling ensured that 4.5W of total laser power delivered over 2 min, would cause an increase of tumor temperature above 45 ℃, and be needed to completely ablate the tumor while minimizing the damage to neighboring tissues. Experimentally, our temperature monitoring results were in line with our predictive modeling, with effective tumor photoablation leading to a significantly reduced post 5-week tumor recurrence using the TSHR-targeted MWCNTs. Ultimately, the results from this study support a utility for photosensitive biologically modified MWCNTs as a cancer therapeutic modality. Further studies will assist with the transition of photothermal therapy from preclinical studies to clinical evaluations.

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.

Computationally guided discovery of novel non-steroidal AR-GR dual antagonists demonstrating potency against antiandrogen resistance

As a major class of medicine for treating the lethal type of castration-resistant prostate cancer (PCa), long-term use of androgen receptor (AR) antagonists commonly leads to antiandrogen resistance. When AR signaling pathway is blocked by AR-targeted therapy, glucocorticoid receptor (GR) could compensate for AR function especially at the late stage of PCa. AR-GR dual antagonist is expected to be a good solution for this situation. Nevertheless, no effective non-steroidal AR-GR dual antagonist has been reported so far. In this study, an AR-GR dual binder H18 was first discovered by combining structure-based virtual screening and biological evaluation. Then with the aid of computationally guided design, the AR-GR dual antagonist HD57 was finally identified with antagonistic activity towards both AR (IC50 = 0.394 μM) and GR (IC50 = 17.81 μM). Moreover, HD57 could effectively antagonize various clinically relevant AR mutants. Further molecular dynamics simulation provided more atomic insights into the mode of action of HD57. Our research presents an efficient and rational strategy for discovering novel AR-GR dual antagonists, and the new scaffold provides important clues for the development of novel therapeutics for castration-resistant PCa.

Preclinical models of prostate cancer - modelling androgen dependency and castration resistance in vitro, ex vivo and in vivo

Prostate cancer is well known to be dependent on the androgen receptor (AR) for growth and survival. Thus, AR is the main pharmacological target to treat this disease. However, after an initially positive response to AR-targeting therapies, prostate cancer will eventually evolve to castration-resistant prostate cancer, which is often lethal. Tumour growth was initially thought to become androgen-independent following treatments; however, results from molecular studies have shown that most resistance mechanisms involve the reactivation of AR. Consequently, tumour cells become resistant to castration - the blockade of testicular androgens - and not independent of AR per se. However, confusion still remains on how to properly define preclinical models of prostate cancer, including cell lines. Most cell lines were isolated from patients for cell culture after evolution of the tumour to castration-resistant prostate cancer, but not all of these cell lines are described as castration resistant. Moreover, castration refers to the blockade of testosterone production by the testes; thus, even the concept of "castration" in vitro is questionable. To ensure maximal transfer of knowledge from scientific research to the clinic, understanding the limitations and advantages of preclinical models, as well as how these models recapitulate cancer cell androgen dependency and can be used to study castration resistance mechanisms, is essential.

Targeting the N-terminal domain of the androgen receptor: The effective approach in therapy of CRPC

The androgen receptor (AR) is dominant in prostate cancer (PCa) pathology. Current therapeutic agents for advanced PCa include androgen synthesis inhibitors and AR antagonists that bind to the hormone binding pocket (HBP) at the ligand binding domain (LBD). However, AR amplification, AR splice variants (AR-Vs) expression, and intra-tumoral de novo synthesis of androgens result in the reactivation of AR signalling. The AR N-terminal domain (NTD) plays an essential role in AR transcriptional activity. The AR inhibitor targeting NTD could potentially block the activation of both full-length AR and AR-Vs, thus overcoming major resistance mechanisms to current treatments. This review discusses the progress of research in various NTD inhibitors and provides new insight into the development of AR-NTD inhibitors.

Claudin-3 Loss of Expression Is a Prognostic Marker in Castration-Resistant Prostate Cancer

Castration-resistant prostate cancer (CRPC) development is the foremost concern after treatment of patients with high risk with locally advanced or metastatic prostate cancer. Androgen receptor (AR) is the main driver of CRPC development, through its interaction with epigenetic modifier genes, placing epigenetics modifications in the forefront of CRPC development. Comparing the DNA methylation and expression profile of androgen-sensitive and -refractory prostate cancer cells, we describe the epigenetic silencing of claudin-3 (CLDN3) in AR positive cells resistant to androgen deprivation (LNCaP-abl). CLDN3 silencing was associated with DNA methylation, loss of histone acetylation and H3K27 methylation, and was re-expressed by the combined treatment with the epigenetic modulators Aza and SAHA. From a functional point of view, CLDN3 loss was associated with increased cellular invasion. Immunohistochemical analysis showed decreased CLDN3 expression in samples from CRPC patients. Interestingly, CLDN3 expression was significantly decreased in samples from patients with high total Gleason score (≥8) and locally advanced tumors. Finally, CLDN3 loss of expression was associated with worse disease-free survival and time to clinical progression. In conclusion, our findings strongly indicate that epigenetic silencing of CLDN3 is a common event in CRPC that could be useful as a molecular marker for the prognosis of prostate cancer patients and to discriminate aggressive from indolent prostate tumors.

Androgen Metabolism and Response in Prostate Cancer Anti-Androgen Therapy Resistance

All aspects of prostate cancer evolution are closely related to androgen levels and the status of the androgen receptor (AR). Almost all treatments target androgen metabolism pathways and AR, from castration-sensitive prostate cancer (CSPC) to castration-resistant prostate cancer (CRPC). Alterations in androgen metabolism and its response are one of the main reasons for prostate cancer drug resistance. In this review, we will introduce androgen metabolism, including how the androgen was synthesized, consumed, and responded to in healthy people and prostate cancer patients, and discuss how these alterations in androgen metabolism contribute to the resistance to anti-androgen therapy.

Androgen receptor mutations for precision medicine in prostate cancer

Hormonal therapies including androgen deprivation therapy and androgen receptor (AR) pathway inhibitors such as abiraterone and enzalutamide have been widely used to treat advanced prostate cancer. However, treatment resistance emerges after hormonal manipulation in most prostate cancers, and it is attributable to a number of mechanisms, including AR amplification and overexpression, AR mutations, the expression of constitutively active AR variants, intra-tumor androgen synthesis, and promiscuous AR activation by other factors. Although various AR mutations have been reported in prostate cancer, specific AR mutations (L702H, W742L/C, H875Y, F877L, and T878A/S) were frequently identified after treatment resistance emerged. Intriguingly, these hot spot mutations were also revealed to change the binding affinity of ligands including steroids and antiandrogens and potentially result in altered responses to AR pathway inhibitors. Currently, precision medicine utilizing genetic and genomic data to choose suitable treatment for the patient is becoming to play an increasingly important role in clinical practice for prostate cancer management. Since clinical data between AR mutations and the efficacy of AR pathway inhibitors are accumulating, monitoring the AR mutation status is a promising approach for providing precision medicine in prostate cancer, which would be implemented through the development of clinically available testing modalities for AR mutations using liquid biopsy. However, there are few reviews on clinical significance of AR hot spot mutations in prostate cancer. Then, this review summarized the clinical landscape of AR mutations and discussed their potential implication for clinical utilization.

Design, Synthesis, and Biological Evaluation of Androgen Receptor Degrading and Antagonizing Bifunctional Steroidal Analogs for the Treatment of Advanced Prostate Cancer

Metastatic castration-resistant prostate cancer (mCRPC) with high mortality has seriously threatened men's health. Bifunctional agents simultaneously degrade and antagonize androgen receptor (AR), display robust AR signaling pathway blockade, and show the therapeutic prospect for mCRPC. Herein, systemic structural modifications on the C-3, C-6, and C-17 positions of galeterone led to the discovery of 67-b with the dual functions of AR antagonism and degradation. In vitro, 67-b exhibited excellent antiproliferative activity and potent AR degradation activity in different PCa cells (LNCaP and 22RV1), as well as outstanding antagonistic activity against wild-type and mutant (W741L, T877A, and F876L) ARs. In vivo, 67-b effectively inhibited the growth of hormone-sensitive organs in the Hershberger assay and exhibited tumor regression in the enzalutamide-resistant (c4-2b-ENZ) xenograft model. These results confirmed 67-b to be a promising AR degrader and antagonist for the treatment of mCRPC patients.

Advances in the Current Understanding of the Mechanisms Governing the Acquisition of Castration-Resistant Prostate Cancer

Despite aggressive treatment and androgen-deprivation therapy, most prostate cancer patients ultimately develop castration-resistant prostate cancer (CRPC), which is associated with high mortality rates. However, the mechanisms governing the development of CRPC are poorly understood, and androgen receptor (AR) signaling has been shown to be important in CRPC through AR gene mutations, gene overexpression, co-regulatory factors, AR shear variants, and androgen resynthesis. A growing number of non-AR pathways have also been shown to influence the CRPC progression, including the Wnt and Hh pathways. Moreover, non-coding RNAs have been identified as important regulators of the CRPC pathogenesis. The present review provides an overview of the relevant literature pertaining to the mechanisms governing the molecular acquisition of castration resistance in prostate cancer, providing a foundation for future, targeted therapeutic efforts.

Structural and molecular insights into the mechanism of resistance to enzalutamide by the clinical mutants in androgen receptor (AR) in castration-resistant prostate cancer (CRPC) patients

Androgen receptor (AR) is a key contributing element in the prostate cancer (PCa) instigation, progression and it is among the vastly discovered target for prostate cancer. Numerous mechanisms trigger the expansion of CRPC among which the aberrant AR gene is considered as the prime factor. Recently three essential substitutions H875Y, F877L, and T878A are reported to cause resistance to Enzalutamide. However, no detailed study is available to explore the key events that contribute to the resistance. Hence, considering the applicability of structural bioinformatics and molecular simulation-based methods in the current study, we assessed the impact of these mutations on the binding of Enzalutamide. Using a long-run simulation approach the binding stability, residues flexibility, hydrogen bonding, and protein compactness for each complex were determined to reveal the dynamic variations induced by these mutations. We discovered that the binding mode of Enzalutamide is altered by these mutations which misstarget the key residues required for the antagonistic activity. Molecular simulation of each complex revealed that the wild type H11 and H12 are more flexible moving outside and provides more volume for the ligand optimization. In the mutant complexes, the H12 remained tighter pushing out enzalutamide from the key residues which then essentially misstarget the correct orientation for the antagonist activity. The binding free energy (BFE) for the wild type was computed to be -59.92 ± 0.18 kcal/mol, for H875Y the BFE was -55.92 ± 0.18 kcal/mol, -54.82 ± 0.15 kcal/mol for F877L and -53.87 ± 0.18 kcal/mol for T878A, which further demonstrate that these mutations have destabilized the binding of enzalutamide. The proteins' motion and FEL further validated the aforementioned findings where the wild type reported different dynamic features than the mutant complexes. In conclusion, this study provides a structural basis for the resistance to Enzalutamide, which can be used to design novel effective drugs using structure-based and rationale approaches.

Novel forms of prostate cancer chemoresistance to successful androgen deprivation therapy demand new approaches: Rationale for targeting BET proteins

In patients with prostate cancer, the duration of remission after treatment with androgen deprivation therapies (ADTs) varies dramatically. Clinical experience has demonstrated difficulties in predicting individual risk for progression due to chemoresistance. Drug combinations that inhibit androgen biosynthesis (e.g., abiraterone acetate) and androgen signaling (e.g., enzalutamide or apalutamide) have proven so effective that new forms of ADT resistance are emerging. In particular, prostate cancers with a neuroendocrine transcriptional signature, which demonstrate greater plasticity, and potentially, increased predisposition to metastasize, are becoming more prevalent. Notably, these subtypes had in fact been relatively rare before the widespread success of novel ADT regimens. Therefore, better understanding of these resistance mechanisms and potential alternative treatments are necessary to improve progression-free survival for patients treated with ADT. Targeting the bromodomain and extra-terminal (BET) protein family, specifically BRD4, with newer investigational agents may represent one such option. Several families of chromatin modifiers appear to be involved in ADT resistance and targeting these pathways could also offer novel approaches. However, the limited transcriptional and genomic information on ADT resistance mechanisms, and a serious lack of patient diversity in clinical trials, demand profiling of a much broader clinical and demographic range of patients, before robust conclusions can be drawn and a clear direction established.

Diptoindonesin G antagonizes AR signaling and enhances the efficacy of antiandrogen therapy in prostate cancer

BACKGROUND

The androgen receptor (AR) signaling pathway has been well demonstrated to play a crucial role in the development, progression, and drug resistance of prostate cancer. Although the current anti-androgen therapy could significantly benefit prostate cancer patients initially, the efficacy of the single drug usually lasts for a relatively short period, as drug resistance quickly emerges.

METHODS

We have performed an unbiased bioinformatics analysis using the RNA-seq results in 22Rv1 cells to identify the cell response toward Dip G treatment. The RNA-seq results were validated by qRT-PCR. Protein levels were detected by western blot or staining. Cell viability was measured by Aquabluer and colony formation assay.

RESULTS

Here, we identified that Diptoindonesin G (Dip G), a natural extracted compound, could promote the proteasome degradation of AR and polo-like kinase 1 (PLK1) through modulating the activation of CHIP E3 ligase. Administration of Dip G has shown a profound efficiency in the suppression of AR and PLK1, not only in androgen-dependent LNCaP cells but also in castration-resistant and enzalutamide-resistant cells in a CHIP-dependent manner. Through co-targeting the AR signaling, Dip G robustly improved the efficacy of HSP90 inhibitors and enzalutamide in both human prostate cancer cells and in vivo xenograft mouse model.

CONCLUSIONS

Our results revealed that Dip G-mediated AR degradation would be a promising and valuable therapeutic strategy in the clinic.

Exploring the effects of genetic variation on gene regulation in cancer in the context of 3D genome structure

Background

Numerous genome-wide association studies (GWAS) conducted to date revealed genetic variants associated with various diseases, including breast and prostate cancers. Despite the availability of these large-scale data, relatively few variants have been functionally characterized, mainly because the majority of single-nucleotide polymorphisms (SNPs) map to the non-coding regions of the human genome. The functional characterization of these non-coding variants and the identification of their target genes remain challenging.

Results

In this communication, we explore the potential functional mechanisms of non-coding SNPs by integrating GWAS with the high-resolution chromosome conformation capture (Hi-C) data for breast and prostate cancers. We show that more genetic variants map to regulatory elements through the 3D genome structure than the 1D linear genome lacking physical chromatin interactions. Importantly, the association of enhancers, transcription factors, and their target genes with breast and prostate cancers tends to be higher when these regulatory elements are mapped to high-risk SNPs through spatial interactions compared to simply using a linear proximity. Finally, we demonstrate that topologically associating domains (TADs) carrying high-risk SNPs also contain gene regulatory elements whose association with cancer is generally higher than those belonging to control TADs containing no high-risk variants.

Conclusions

Our results suggest that many SNPs may contribute to the cancer development by affecting the expression of certain tumor-related genes through long-range chromatin interactions with gene regulatory elements. Integrating large-scale genetic datasets with the 3D genome structure offers an attractive and unique approach to systematically investigate the functional mechanisms of genetic variants in disease risk and progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12863-021-01021-x.

Folic Acid-Modified miR-491-5p-Loaded ZIF-8 Nanoparticles Inhibit Castration-Resistant Prostate Cancer by Regulating the Expression of EPHX1

Epoxide hydrolase 1 (EPHX1) has been reported to be related to the development of several tumors. However, the regulation of castration-resistant prostate cancer (CRPC) development by EPHX1 has not been reported. We used proteomic technology and found that the EPHX1 protein was highly expressed in CRPC tissues and the CRPC cell line C4-2. We performed screening and found that EPHX1 is a direct target of miR-491-5p. High miR-491-5p expression significantly reduced the EPHX1 level in C4-2 cells and inhibited C4-2 cell proliferation and migration. Zeolite imidazolate framework-8 (ZIF-8) has good thermal stability, a simple synthesis method, tumor site stability, and specific acid responsiveness. We synthesized ZIF-8 nanodrug vectors to deliver miR-491-5p into C4-2 cells. After loading miR-491-5p into ZIF-8, we modified the ZIF-8 surface with folic acid (FA) as the target group (FA@ZIF-8). Our synthesized nanodrug carrier showed less cytotoxicity to C4-2 cells even at 200 μg/ml. Modified FA could increase the efficiency of nanomaterial entry into C4-2 cells. FA@miR-491-5p@ZIF-8 could stably release miR-491-5p for a long period in both phosphate-buffered saline (pH 7.4) and acetate buffer (pH 4.8), and miR-491-5p was released faster at the beginning of the experiment in acetate buffer (pH 4.8). FA@miR-491-5p@ZIF-8 significantly reduced C4-2 cell proliferation and migration, and FA@miR-491-5p@ZIF-8 had a better effect than miR-491-5p alone. In vivo, FA@miR-491-5p@ZIF-8 significantly inhibited CRPC growth in nude mice. Overall, we verified that miR-491-4p regulated CRPC development by targeting EPHX1. The drug nanocarrier FA@miR-491-5p@ZIF-8 not only significantly reduced C4-2 CRPC cell proliferation and migration but also significantly inhibited CRPC growth. Our research provides a theoretical basis for treatment and treatment strategies for CRPC.

Androgen deprivation‑induced OPHN1 amplification promotes castration‑resistant prostate cancer

Androgen deprivation therapy (ADT) is used to treat prostate cancer (PCa). However, ADT may increase the expression of androgen receptor (AR) through the amplification of chromosome X. The gene oligophrenin 1 (OPHN1) is located in the same region as the AR gene, which could be amplified by ADT. Thus, the role of OPHN1 in PCa pathology was investigated. The expression status of OPHN1 in PCa was searched in The Cancer Genome Atlas (TCGA) database. Androgen-sensitive cells LNCaP and 22RV1 were cultured under ADT conditions, and then the expression of OPHN1 was evaluated by northern blotting. The expression of OPHN1 was enhanced or knocked down in LNCaP and 22RV1 cells by transfection. Subsequently, the LNCaP and 22RV1 cells were cultured under ADT, and the viability rate, apoptosis, and migration of cells were assessed by MTT, flow cytometry, and Transwell assay respectively. The expression of OPHN1 was also enhanced or knocked down in androgen-insensitive PC3 cells, and then the effects of OPHN1 on the viability, apoptosis, and migration of PC3 cells were assessed. A mouse xenograft model was created by injecting LNCaP cells with OPHN1 overexpression subcutaneously, and the tumor growth rates were monitored. In TCGA database, amplification of the OPHN1 gene was observed in the PCa tumors. ADT increased the expression of OPHN1 in LNCaP and 22RV1 cells (P<0.05). OPHN1 could promote resistance of LNCaP and 22RV1 cells to ADT by promoting cell survival and preventing their apoptosis (P<0.05). In addition, OPHN1 contributed to cell viability (P<0.05) and enhanced the migration ability in LNCaP, 22RV1 and PC3 cells (P<0.05). In the mouse model, the PCa xenograft with OPHN1 overexpression had a higher growth rate and was more resistant to the ADT condition (P<0.05). In summary, ADT induced the overexpression of OPHN1 in PCa, which facilitated PCa cell survival and promoted PCa progression.

Molecular Phenotyping of AR Signaling for Predicting Targeted Therapy in Castration Resistant Prostate Cancer

Castration-resistant prostate cancer (CRPC) is defined by resistance of the tumor to androgen deprivation therapy (ADT). Several molecular changes, particularly in the AR signaling cascade, have been described that may explain ADT resistance. The variety of changes may also explain why the response to novel therapies varies between patients. Testing the specific molecular changes may be a major step towards personalized treatment of CRPC patients. The aim of our study was to evaluate the molecular changes in the AR signaling cascade in CRPC patients. We have developed and validated several methods which are easy to use, and require little tissue material, for exploring AR signaling pathway changes simultaneously. We found that the AR signaling pathway is still active in the majority of our CRPC patients, due to molecular changes in AR signaling components. There was heterogeneity in the molecular changes observed, but we could classify the patients into 4 major subgroups which are: AR mutation, AR amplification, active intratumoral steroidogenesis, and combination of AR amplification and active intratumoral steroidogenesis. We suggest characterizing the AR signaling pathway in CRPC patients before beginning any new treatment, and a recent fresh tissue sample from the prostate or a metastatic site should be obtained for the purpose of this characterization.

Limited evolution of the actionable metastatic cancer genome under therapeutic pressure

Genomic profiling is critical for the identification of treatment options for patients with metastatic cancer, but it remains unclear how frequently this procedure should be repeated during the course of the disease. To address this, we analyzed whole-genome sequencing (WGS) data of 250 biopsy pairs, longitudinally collected over the treatment course of 231 adult patients with a representative variety of metastatic solid malignancies. Within the biopsy interval (median, 6.4 months), patients received one or multiple lines of (mostly) standard-of-care (SOC) treatments, with all major treatment modalities being broadly represented. SOC biomarkers and biomarkers for clinical trial enrollment could be identified in 23% and 72% of biopsies, respectively. For SOC genomic biomarkers, we observed full concordance between the first and the second biopsy in 99% of pairs. Of the 219 biomarkers for clinical trial enrollment that were identified in the first biopsies, we recovered 94% in the follow-up biopsies. Furthermore, a second WGS analysis did not identify additional biomarkers for clinical trial enrollment in 91% of patients. More-frequent genomic evolution was observed when considering specific genes targeted by small-molecule inhibitors or hormonal therapies (21% and 22% of cases, respectively). Together, our data demonstrate that there is limited evolution of the actionable genome of treated metastases. A single WGS analysis of a metastatic biopsy is generally sufficient to identify SOC genomic biomarkers and to identify investigational treatment opportunities.

Treatment and trials in non-metastatic castration-resistant prostate cancer

Metastatic prostate cancer is associated with considerable morbidity and mortality. Standard treatment for non-metastatic prostate cancer, to prevent metastatic progression, is androgen deprivation therapy (ADT); however, many patients will eventually develop castration-resistant prostate cancer (CRPC), which can prove challenging to treat. Between the stages of non-metastatic androgen-sensitive disease and metastatic CRPC is an intermediate disease state that has been termed non-metastatic CRPC (nmCRPC), which is a heterogeneous, man-made disease stage that occurs after a patient who has no radiological evidence of metastasis shows evidence of cancer progression even after ADT. Awareness of nmCRPC has risen owing to an increased use of ADT and its eventual failure. Men with nmCRPC are at a high risk of progression to mCRPC, with historically few options to halt this process. However, in the past two decades, multiple therapies have been investigated for the treatment of nmCRPC, including endothelin receptor antagonists and bone-targeted therapies, but none has changed the standard of care. In the past decade, the efficacy of androgen receptor pathway-targeting modalities has been investigated. Three novel nonsteroidal antiandrogen agents for treating high-risk nmCRPC have been investigated; the PROSPER, SPARTAN and ARAMIS trials were phase III, randomized, placebo-controlled clinical trials that investigated the efficacy and safety of enzalutamide, apalutamide and darolutamide, respectively. All three therapeutics showed statistically significant improvements in metastasis-free survival, progression to antineoplastic therapy was lengthened and at final analysis, overall survival was significantly improved. The comparative efficacy and safety of all three agents has not yet been investigated in a comprehensive clinical trial, but approval of these medications by the FDA and other regulatory agencies means that providers now have three effective therapeutic options to augment ADT for patients with nmCRPC.

Androgen Receptor Signaling in Prostate Cancer Genomic Subtypes

While many prostate cancer (PCa) cases remain indolent and treatable, others are aggressive and progress to the metastatic stage where there are limited curative therapies. Androgen receptor (AR) signaling remains an important pathway for proliferative and survival programs in PCa, making disruption of AR signaling a viable therapy option. However, most patients develop resistance to AR-targeted therapies or inherently never respond. The field has turned to PCa genomics to aid in stratifying high risk patients, and to better understand the mechanisms driving aggressive PCa and therapy resistance. While alterations to the AR gene itself occur at later stages, genomic changes at the primary stage can affect the AR axis and impact response to AR-directed therapies. Here, we review common genomic alterations in primary PCa and their influence on AR function and activity. Through a meta-analysis of multiple independent primary PCa databases, we also identified subtypes of significantly co-occurring alterations and examined their combinatorial effects on the AR axis. Further, we discussed the subsequent implications for response to AR-targeted therapies and other treatments. We identified multiple primary PCa genomic subtypes, and given their differing effects on AR activity, patient tumor genetics may be an important stratifying factor for AR therapy resistance.

T-LAK cell-originated protein kinase (TOPK) enhances androgen receptor splice variant (ARv7) and drives androgen-independent growth in prostate cancer

Despite impressive advances in the treatment of prostate cancer with various efficacious inhibitors along the androgen/androgen receptor axis, eventual development of incurable metastatic Castration-Resistant Prostate Cancer (mCRPC) is inevitable and remains a major clinical challenge. Constitutively active androgen receptor (AR) spliced variants have emerged as primary means of resistance to anti-androgens and androgen synthesis inhibitors. The alternatively spliced AR variant, ARv7, has attracted significant interest due to its constitutively active status in CRPC that drives androgen-independence. Factors that are involved in regulating ARv7 levels in CRPC are not clearly known. We recently demonstrated that a protein kinase, T-LAK cell-originated protein kinase (TOPK) level correlates with the aggressiveness of prostate cancer and its invasive behavior. In this study, we investigated whether TOPK plays a role in driving androgen-independence in prostate cancer cells. Our data demonstrate that TOPK overexpression in androgen-dependent LNCaP and VCaP induces ARv7 and drives androgen-independent growth. On the other hand, pharmacological inhibition of TOPK in androgen-independent LNCaP95 and 22Rv1 represses AR transactivation, and AR stability. In summary, this study illustrates a direct role of TOPK in regulating ARv7 and driving androgen-independence in prostate cancer cells.

Undesirable Status of Prostate Cancer Cells after Intensive Inhibition of AR Signaling: Post-AR Era of CRPC Treatment

Recent advances in prostate cancer (PC) research unveiled real androgen receptor (AR) functions in castration-resistant PC (CRPC). Moreover, AR still accelerates PC cell proliferation via the activation of several mechanisms (e.g., mutation, variants, and amplifications in CRPC). New-generation AR signaling-targeted agents, inhibiting extremely the activity of AR, were developed based on these incontrovertible mechanisms of AR-induced CRPC progression. However, long-term administration of AR signaling-targeted agents subsequently induces the major problem that AR (complete)-independent CRPC cells present neither AR nor prostate-specific antigen, including neuroendocrine differentiation as a subtype of AR-independent CRPC. Moreover, there are few treatments effective for AR-independent CRPC with solid evidence. This study focuses on the transformation mechanisms of AR-independent from AR-dependent CRPC cells and potential treatment strategy for AR-independent CRPC and discusses them based on a review of basic and clinical literature.

Cross-Resistance to Abiraterone and Enzalutamide in Castration Resistance Prostate Cancer Cellular Models Is Mediated by AR Transcriptional Reactivation

Androgen deprivation therapy (ADT) and novel hormonal agents (NHAs) (Abiraterone and Enzalutamide) are the goal standard for metastatic prostate cancer (PCa) treatment. Although ADT is initially effective, a subsequent castration resistance status (CRPC) is commonly developed. The expression of androgen receptor (AR) alternative splicing isoforms (AR-V7 and AR-V9) has been associated to CRPC. However, resistance mechanisms to novel NHAs are not yet well understood. Androgen-dependent PCa cell lines were used to generate resistant models to ADT only or in combination with Abiraterone and/or Enzalutamide (concomitant models). Functional and genetic analyses were performed for each resistance model by real-time cell monitoring assays, flow cytometry and RT-qPCR. In androgen-dependent PCa cells, the administration of Abiraterone and/or Enzalutamide as first-line treatment involved a critical inhibition of AR activity associated with a significant cell growth inhibition. Genetic analyses on ADT-resistant PCa cell lines showed that the CRPC phenotype was accompanied by overexpression of AR full-length and AR target genes, but not necessarily AR-V7 and/or AR-V9 isoforms. These ADT resistant cell lines showed higher proliferation rates, migration and invasion abilities. Importantly, ADT resistance induced cross-resistance to Abiraterone and/or Enzalutamide. Similarly, concomitant models possessed an elevated expression of AR full-length and proliferation rates and acquired cross-resistance to its alternative NHA as second-line treatment.

New Prognostic Biomarkers in Metastatic Castration-Resistant Prostate Cancer

Prostate cancer is one of the most frequent cancers in men and is a common cause of cancer-related death. Despite significant progress in the diagnosis and treatment of this tumor, patients who relapse after radical treatments inevitably develop metastatic disease. Patient stratification is therefore key in this type of cancer, and there is an urgent need for prognostic biomarkers that can define patients' risk of cancer-related death. In the last 10 years, multiple prognostic factors have been identified and studied. Here, we review the literature available and discuss the most common aberrant genomic pathways in metastatic castration-resistant prostate cancer shown to have a prognostic relevance in this setting.

Structure–activity relationship analysis of a series of nonsteroidal analogues as androgen receptor antagonists

Computer-aided drug design technology was used to screen drugs in large-scale and to accelerate the progress of drug design of nonsteroidal compounds deriving from the hybridization of FDA-approved Enzalutamide and Abiraterone.

Metabolic Reprogramming and Predominance of Solute Carrier Genes during Acquired Enzalutamide Resistance in Prostate Cancer

Androgen deprivation therapy (ADT) is standard-of-care for advanced-stage prostate cancer, and enzalutamide (Xtandi^®, Astellas, Northbrook, IL, USA), a second generation antiandrogen, is prescribed in this clinical setting. The response to this medication is usually temporary with the rapid emergence of drug resistance. A better understanding of gene expression changes associated with enzalutamide resistance will facilitate circumventing this problem. We compared the transcriptomic profile of paired enzalutamide-sensitive and resistant LNCaP and C4-2B prostate cancer cells for identification of genes involved in drug resistance by performing an unbiased bioinformatics analysis and further validation. Next-Gen sequencing detected 9409 and 7757 genes differentially expressed in LNCaP and C4-2B cells, compared to their parental counterparts. A subset of differentially expressed genes were validated by qRT-PCR. Analysis by the i-pathway revealed membrane transporters including solute carrier proteins, ATP-binding cassette transporters, and drug metabolizing enzymes as the most prominent genes dysregulated in resistant cell lines. RNA-Seq data demonstrated predominance of solute carrier genes SLC12A5, SLC25A17, and SLC27A6 during metabolic reprogramming and development of drug resistance. Upregulation of these genes were associated with higher uptake of lactic/citric acid and lower glucose intake in resistant cells. Our data suggest the predominance of solute carrier genes during metabolic reprogramming of prostate cancer cells in an androgen-deprived environment, thus signifying them as potentially attractive therapeutic targets.

Interplay between orphan nuclear receptors and androgen receptor-dependent or-independent growth signalings in prostate cancer

It is well-established that both the initial and advanced growth of prostate cancer depends critically on androgens and thus on the activated androgen receptor (AR) -mediated signaling pathway. The unique hormone-dependent feature of prostate cancer forms the biological basis of hormone or androgen-deprivation therapy (ADT) that aims to suppress the AR signaling by androgen depletion or AR antagonists. ADT still remains the mainstay treatment option for locally advanced or metastatic prostate cancer. However, most patients upon ADT will inevitably develop therapy-resistance and progress to relapse in the form of castration-resistant disease (castration-resistant prostate cancer or CRPC) or even a more aggressive androgen-independent subtype (therapy-related neuroendocrine prostate cancer or NEPC). Recent advances show that besides AR, some ligand-independent members of nuclear receptor superfamily-designated as orphan nuclear receptors (ONRs), as their endogenous physiological ligands are either absent or not yet identified to date, also play significant roles in the growth regulation of prostate cancer via multiple AR-dependent or -independent (AR-bypass) pathways or mechanisms. In this review, we summarize the recent progress in the newly elucidated roles of ONRs in prostate cancer, with a focus on their interplay in the AR-dependent pathways (intratumoral androgen biosynthesis and suppression of AR signaling) and AR-independent pathways or cellular processes (hypoxia, oncogene- or tumor suppressor-induced senescence, apoptosis and regulation of prostate cancer stem cells). These ONRs with their newly characterized roles not only can serve as novel biomarkers but also as potential therapeutic targets for management of advanced prostate cancer.

Exploring the effects of genetic variation on gene regulation in cancer in the context of 3D genome structure.. [DOI: 10.1101/2020.10.06.328567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Numerous genome-wide association studies (GWAS) conducted to date revealed genetic variants associated with various diseases, including breast and prostate cancers. Despite the availability of these large-scale data, relatively few variants have been functionally characterized, mainly because the majority of single-nucleotide polymorphisms (SNPs) map to the non-coding regions of the human genome. The functional characterization of these non-coding variants and the identification of their target genes remain challenging. In this communication, we explore the potential functional mechanisms of non-coding SNPs by integrating GWAS with the high-resolution chromosome conformation capture (Hi-C) data for breast and prostate cancers. We show that more genetic variants map to regulatory elements through the 3D genome structure than the 1D linear genome lacking physical chromatin interactions. Importantly, the association of enhancers, transcription factors, and their target genes with breast and prostate cancers tends to be higher when these regulatory elements are mapped to high-risk SNPs through spatial interactions compared to simply using a linear proximity. Finally, we demonstrate that topologically associating domains (TADs) carrying high-risk SNPs also contain gene regulatory elements whose association with cancer is generally higher than those belonging to control TADs containing no high-risk variants. Our results suggest that many SNPs may contribute to the cancer development by affecting the expression of certain tumor-related genes through long-range chromatin interactions with gene regulatory elements. Integrating large-scale genetic datasets with the 3D genome structure offers an attractive and unique approach to systematically investigate the functional mechanisms of genetic variants in disease risk and progression.

Overcoming the mechanisms of primary and acquired resistance to new generation hormonal therapies in advanced prostate cancer: focus on androgen receptor independent pathways

In recent years, many therapeutic advances have been made in the management of castration-resistant prostate cancer, with the development and approval of many new drugs. The androgen receptor (AR) is the main driver in prostate cancer growth and progression and the most effective therapeutic agents are still directed against this pathway. Among these, new generation hormonal agents (NHA) including enzalutamide, abiraterone acetate, apalutamide, and darolutamide have shown to improve overall survival and quality of life of prostate cancer patients. Unfortunately, despite the demonstrated benefit, not all patients respond to treatment and almost all are destined to develop a resistant phenotype. Although the resistance mechanisms are not fully understood, the most studied ones include the activation of both dependent and independent AR signalling pathways. Recent findings about multiple growth-promoting and survival pathways in advanced prostate cancer suggest the presence of alternative mechanisms involved in disease progression, and an interplay between these pathways and AR signalling. In this review we discuss the possible mechanisms of primary and acquired resistance to NHA with a focus on AR independent pathways.

Stabilization of ADAM9 by N-α-acetyltransferase 10 protein contributes to promoting progression of androgen-independent prostate cancer

N-α-Acetyltransferase 10 protein (Naa10p) was reported to be an oncoprotein in androgen-dependent prostate cancer (PCa; ADPC) through binding and increasing transcriptional activity of the androgen receptor (AR). PCa usually progresses from an androgen-dependent to an androgen-independent stage, leading to an increase in the metastatic potential and an incurable malignancy. At present, the role of Naa10p in androgen-independent prostate cancer (AIPC) remains unclear. In this study, in silico and immunohistochemistry analyses showed that Naa10 transcripts or the Naa10p protein were more highly expressed in primary and metastatic PCa cancer tissues compared to adjacent normal tissues and non-metastatic cancer tissues, respectively. Knockdown and overexpression of Naa10p in AIPC cells (DU145 and PC-3M), respectively, led to decreased and increased cell clonogenic and invasive abilities in vitro as well as tumor growth and metastasis in AIPC xenografts. From the protease array screening, we identified a disintegrin and metalloprotease 9 (ADAM9) as a potential target of Naa10p, which was responsible for the Naa10p-induced invasion of AIPC cells. Naa10p can form a complex with ADAM9 to maintain ADAM9 protein stability and promote AIPC's invasive ability which were independent of its acetyltransferase activity. In contrast to the Naa10p-ADAM9 axis, ADAM9 exerted positive feedback regulation on Naa10p to modulate progression of AIPC in vitro and in vivo. Taken together, for the first time, our results reveal a novel cross-talk between Naa10p and ADAM9 in regulating the progression of AIPC. Disruption of Naa10p-ADAM9 interactions may be a potential intervention for AIPC therapy.

Integrative Exome Sequencing Analysis in Castration-Resistant Prostate Cancer in Chinese Population

BACKGROUND

Castration-resistant Prostate Cancer (CRPC) is a fatal disease with rapid growth. The malignancy usually presents with metastasis and poor prognosis, and causes 100% mortality. Therefore, the treatment of CRPC is extremely challenging, and its pathogenesis need to be elucidated urgently.

OBJECTIVE

The high throughput sequencing technology was used to sequence the whole exome associated with CRPC, to explore the molecular mechanism of CRPC, and to find the potential therapeutic targets.

METHODS

We performed whole-exome sequencing of FFPE tissue from 11 Chinese adult male patients. Genomic DNA was fragmented and enriched for whole-exome sequencing using the QiAamp DNA FFPE Tissue KIT, sequenced on an Illumina HiSeq2000 platform, and the relevant genes were analyzed using biological information. Finally, immunohistochemistry method was used to detect the phosphorylation level of LATS1 in CRPC tissues of MST1 mutant and non-mutant patients.

RESULTS

We have screened 85 significant mutant genes with relatively high mutation rates of TP53, AR, KMT2, DMAPK1, PIK3R1, SH2B3, WHSC1, KMT2D, MST1 and MAPK1. We first found that MST1 has multiple mutations in CRPC patients, and the MST1 plays an important role in the Hippo pathway. Immunohistochemistry results showed that the phosphorylation level of LATS1 in the mutant patients was significantly lower than that in the non-mutant patients.

CONCLUSION

We speculate that MST1 would be a new potential target for the treatment of CRPC by regulating Hippo signaling pathway. The results provided an important clue to the molecular mechanism of CRPC.

Regression of castration-resistant prostate cancer by a novel compound QW07 targeting androgen receptor N-terminal domain

Androgen deprivation therapy (ADT) via surgical or chemical castration frequently fails to halt lethal castration-resistant prostate cancer (CRPC), which is induced by multiple mechanisms involving constitutive androgen receptor (AR) splice variants, AR mutation, and/or de novo androgen synthesis. The AR N-terminal domain (NTD) possesses most transcriptional activity and is proposed as a potential target for CRPC drug development. We constructed a screening system targeting AR-NTD transcription activity to screening a compound library and identified a novel small molecule compound named QW07. The function evaluation and mechanism investigation of QW07 were carried out in vitro and in vivo. QW07 bound to AR-NTD directly, blocked the transactivation of AR-NTD, blocked interactions between co-regulatory proteins and androgen response elements (AREs), inhibited the expression of genes downstream of AR, and inhibited prostate cancer growth in vitro and in vivo. QW07 was demonstrated as an AR-NTD-specific antagonist with the potential to inhibit both canonical and variant-mediated AR signaling to regress the CRPC xenografts and is proposed as a lead compound for a specific antagonist targeting AR-NTD.

Androgen Receptor in Breast Cancer: From Bench to Bedside

Breast cancer (BC) is one of the most common malignancies and the leading cause of cancer-related mortality in women. Androgen receptor (AR) is frequently expressed in diverse BC subtypes. Accumulating evidence has revealed that AR might be a predictive or prognostic factor and a drug target in BC. AR expression and AR pathways differ in various BC subtypes, thereby resulting in controversial inferences on the predictive and prognostic value of AR. Herein, we summarized the roles of AR in different BC subtypes and AR-targeting therapies based on preclinical and clinical studies. Moreover, we highlighted the possible efficacy of a combination therapy via exploiting the AR-related mechanisms and the research on therapeutic resistance.

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.

Structure and Function of the Nuclear Receptor Superfamily and Current Targeted Therapies of Prostate Cancer

The nuclear receptor superfamily comprises a large group of proteins with functions essential for cell signaling, survival, and proliferation. There are multiple distinctions between nuclear superfamily classes defined by hallmark differences in function, ligand binding, tissue specificity, and DNA binding. In this review, we utilize the initial classification system, which defines subfamilies based on structure and functional difference. The defining feature of the nuclear receptor superfamily is that these proteins function as transcription factors. The loss of transcriptional regulation or gain of functioning of these receptors is a hallmark in numerous diseases. For example, in prostate cancer, the androgen receptor is a primary target for current prostate cancer therapies. Targeted cancer therapies for nuclear hormone receptors have been more feasible to develop than others due to the ligand availability and cell permeability of hormones. To better target these receptors, it is critical to understand their structural and functional regulation. Given that late-stage cancers often develop hormone insensitivity, we will explore the strengths and pitfalls of targeting other transcription factors outside of the nuclear receptor superfamily such as the signal transducer and activator of transcription (STAT).

Characterization of glycine-N-acyltransferase like 1 (GLYATL1) in prostate cancer

BACKGROUND

Recent microarray and sequencing studies of prostate cancer showed multiple molecular alterations during cancer progression. It is critical to evaluate these molecular changes to identify new biomarkers and targets. We performed analysis of glycine-N-acyltransferase like 1 (GLYATL1) expression in various stages of prostate cancer in this study and evaluated the regulation of GLYATL1 by androgen.

METHOD

We performed in silico analysis of cancer gene expression profiling and transcriptome sequencing to evaluate GLYATL1 expression in prostate cancer. Furthermore, we performed immunohistochemistry using specific GLYATL1 antibody using high-density prostate cancer tissue microarray containing primary and metastatic prostate cancer. We also tested the regulation of GLYATL1 expression by androgen and ETS transcription factor ETV1. In addition, we performed RNA-sequencing of GLYATL1 modulated prostate cancer cells to evaluate the gene expression and changes in molecular pathways.

RESULTS

Our in silico analysis of cancer gene expression profiling and transcriptome sequencing we revealed an overexpression of GLYATL1 in primary prostate cancer. Confirming these findings by immunohistochemistry, we show that GLYATL1 is overexpressed in primary prostate cancer compared with metastatic prostate cancer and benign prostatic tissue. Low-grade cancers had higher GLYATL1 expression compared to high-grade prostate tumors. Our studies showed that GLYATL1 is upregulated upon androgen treatment in LNCaP prostate cancer cells which harbors ETV1 gene rearrangement. Furthermore, ETV1 knockdown in LNCaP cells showed downregulation of GLYATL1 suggesting potential regulation of GLYATL1 by ETS transcription factor ETV1. Transcriptome sequencing using the GLYATL1 knockdown prostate cancer cell lines LNCaP showed regulation of multiple metabolic pathways.

CONCLUSIONS

In summary, our study characterizes the expression of GLYATL1 in prostate cancer and explores the regulation of its regulation in prostate cancer showing role for androgen and ETS transcription factor ETV1. Future studies are needed to decipher the biological significance of these findings.

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

Prostate cancer is the leading cause of cancer and second leading cause of cancer-related death in men in the United States. Twenty percent of patients receiving the standard of care androgen deprivation therapy (ADT) eventually progress to metastatic and incurable castration-resistant prostate cancer (CRPC). Current FDA-approved drugs for CRPC target androgen receptor (AR) binding or androgen production, but only provide a 2- to 5-month survival benefit due to the emergence of resistance. Overexpression of AR coactivators and the emergence of AR splice variants, both promote continued transcriptional activation under androgen-depleted conditions and represent drug resistance mechanisms that contribute to CRPC progression. The AR contains two transactivation domains, activation function 2 (AF-2) and activation function 1 (AF-1), which serve as binding surfaces for coactivators involved in the transcriptional activation of AR target genes. Full-length AR contains both AF-2 and AF-1 surfaces, whereas AR splice variants only have an AF-1 surface. We have recently prosecuted a high-content screening campaign to identify hit compounds that can inhibit or disrupt the protein-protein interactions (PPIs) between AR and transcriptional intermediary factor 2 (TIF2), one of the coactivators implicated in CRPC disease progression. Since an ideal inhibitor/disruptor of AR-coactivator PPIs would target both the AF-2 and AF-1 surfaces, we describe here the development and validation of five AF-2- and three AF-1-focused assays to interrogate and prioritize hits that disrupt both transactivation surfaces. The assays were validated using a test set of seven known AR modulator compounds, including three AR antagonists and one androgen synthesis inhibitor that are FDA-approved ADTs, two investigational molecules that target the N-terminal domain of AR, and an inhibitor of the Hsp90 (heat shock protein) molecular chaperone.

Discovery and development of ODM-204: A Novel nonsteroidal compound for the treatment of castration-resistant prostate cancer by blocking the androgen receptor and inhibiting CYP17A1

We report the discovery of a novel nonsteroidal dual-action compound, ODM-204, that holds promise for treating patients with castration-resistant prostate cancer (CRPC), an advanced form of prostate cancer characterised by high androgen receptor (AR) expression and persistent activation of the AR signaling axis by residual tissue androgens. For ODM-204, has a dual mechanism of action. The compound is anticipated to efficiently dampen androgenic stimuli in the body by inhibiting CYP17A1, the prerequisite enzyme for the formation of dihydrotestosterone (DHT) and testosterone (T), and by blocking AR with high affinity and specificity. In our study, ODM-204 inhibited the proliferation of androgen-dependent VCaP and LNCaP cells in vitro and reduced significantly tumour growth in a murine VCaP xenograft model in vivo. Intriguingly, after a single oral dose of 10-30 mg/kg, ODM-204 dose-dependently inhibited adrenal and testicular steroid production in sexually mature male cynomolgus monkeys. Similar results were obtained in human chorionic gonadotropin-treated male rats. In rats, leuprolide acetate-mediated (LHRH agonist) suppression of the circulating testosterone levels and decrease in weights of androgen-sensitive organs was significantly and dose-dependently potentiated by the co-administration of ODM-204. ODM-204 was well tolerated in both rodents and primates. Based on our data, ODM-204 could provide an effective therapeutic option for men with CRPC.

Discovery and biological evaluation of darolutamide derivatives as inhibitors and down-regulators of wild-type AR and the mutants

Androgen receptor (AR) has been a target of prostate cancer (PC) for nearly six decades. Recently, downregulating or degrading AR and the mutants especially the splice variant 7 (AR-V7) lacking ligand binding domain (LBD) emerged as an advantageous therapeutic approach to overcome drug resistance. Here, the structural modification of darolutamide resulted in the discovery of dual-action AR inhibitors and down-regulators. Unlike other traditional AR antagonists targeting the AR-LBD, compounds 4k and 4b not only inhibit the activities of wt-AR and AR-F876L mutant but also downregulate the protein expression of full-length (AR-full) and AR variant 7 (AR-V7) at mRNA level. In cell proliferation assays, compounds 4k and 4b exhibited better antiproliferative activities than darolutamide and enzalutamide against AR-V7-positive 22Rv1 cells and VCaP cells. In addition, 4k demonstrated better antitumor activity than clinically used enzalutamide in castration-resistant VCaP xenograft model. Collectively, combining the activities of AR inhibition and downregulation, compound 4k is proposed as an advantageous lead compound to disrupt AR signaling and overcome resistance.

Androgen receptor splice variants bind to constitutively open chromatin and promote abiraterone-resistant growth of prostate cancer

Androgen receptor (AR) splice variants (ARVs) are implicated in development of castration-resistant prostate cancer (CRPC). Upregulation of ARVs often correlates with persistent AR activity after androgen deprivation therapy (ADT). However, the genomic and epigenomic characteristics of ARV-dependent cistrome and the disease relevance of ARV-mediated transcriptome remain elusive. Through integrated chromatin immunoprecipitation coupled sequencing (ChIP-seq) and RNA sequencing (RNA-seq) analysis, we identified ARV-preferential-binding sites (ARV-PBS) and a set of genes preferentially transactivated by ARVs in CRPC cells. ARVs preferentially bind to enhancers located in nucleosome-depleted regions harboring the full AR-response element (AREfull), while full-length AR (ARFL)-PBS are enhancers resided in closed chromatin regions containing the composite FOXA1-nnnn-AREhalf motif. ARV-PBS exclusively overlapped with AR binding sites in castration-resistant (CR) tumors in patients and ARV-preferentially activated genes were up-regulated in abiraterone-resistant patient specimens. Expression of ARV-PBS target genes, such as oncogene RAP2A and cell cycle gene E2F7, were significantly associated with castration resistance, poor survival and tumor progression. We uncover distinct genomic and epigenomic features of ARV-PBS, highlighting that ARVs are useful tools to depict AR-regulated oncogenic genome and epigenome landscapes in prostate cancer. Our data also suggest that the ARV-preferentially activated transcriptional program could be targeted for effective treatment of CRPC.

Discovery and biological evaluation of novel androgen receptor antagonist for castration-resistant prostate cancer

Prostate cancer (PC) is the second most common malignancy in men worldwide. Among current therapies, two antiandrogens, Abiraterone Acetate and Enzalutamide (Enza) have become the standard of care for patients with metastatic castration-resistant prostate cancer (mCRPC). Here, we designed and synthesized a new series of nonsteroidal compounds deriving from the hybridization of Abiraterone (Abi) and Enzalutamide, among which compound 4a featuring the diphenylamine scaffold was identified as a potent and cell selective androgen receptor (AR) antagonist. In cell proliferation assays, compound 4a exhibited better antiproliferative activities than Enzalutamide against AR-overexpressing VCaP cells and 22Rv1 cells bearing H874Y-mutated AR. In addition, 4a suppressed the activity of AR-F876L mutant that confers resistance to Enzalutamide and efficiently blocked R1881-induced PSA and FKBP5 gene expression. In competitive binding assay, compound 4a displayed higher binding affinity to AR than Enzalutamide. These results suggest compound 4a as a potential candidate to treat Enza-resistant CRPC.

MIIP inhibits the growth of prostate cancer via interaction with PP1α and negative modulation of AKT signaling

Background

Over-activation of phosphatidylinositol 3-kinase (PI3K)-AKT-mammalian target of rapamycin (mTOR) signaling pathway is one of important mechanisms to promote castration resistant prostate cancer, the final stage of prostate cancer (PCa). Dysregulation of PP1-meditaed AKT dephosphorylation might contribute to such an event but is not fully understood. As a newly identified tumor suppressor, MIIP exerts its role in various types of cancer but has not been investigated in PCa.

Results

We first demonstrated that overexpression of migration and invasion inhibitory protein (MIIP) in human PCa cell lines suppresses their growth while knockdown of MIIP does the opposite in vitro. Although MIIP has no effect on the expression of AR and its target genes or the nuclear translocation of AR in AR-positive PCa cells, MIIP overexpression significantly inhibits activation of AKT-mTOR pathway in both AR- positive and negative PCa cells whereas knockdown of MIIP enhances AKT-mTOR signaling. Using Western blot, immunofluorescence co-localization and co-immunoprecipitation analysis, we found that MIIP interacts with PP1α via its C-terminal part but does not affect its protein level. Importantly, silence of PP1α reversed the inhibitory effect of MIIP on AKT phosphorylation and cell growth in PCa cell lines, while MIIP∆C, which is incapable of interacting with PP1α, loses MIIP’s effect, suggesting that MIIP exerts its roles via interaction with PP1α. Further, MIIP overexpression inhibits the growth of both AR- positive and negative PCa xenograft in nude mice. Finally, immunohistochemical staining of PCa tissue microarray showed that MIIP expression level is downregulated in PCa and negatively correlated with Gleason score of PCa.

Conclusion

We discovered that MIIP is a novel suppressor of oncogenic AKT-mTOR signaling in PCa by facilitating PP1-meditaed AKT dephosphorylation. Our study further emphasized the tumor suppressive role of MIIP and illustrated a novel mechanism.

Electronic supplementary material

The online version of this article (10.1186/s12964-019-0355-1) contains supplementary material, which is available to authorized users.