Androgen receptor signaling and mutations in prostate cancer

Aberrant activated Notch1 promotes prostate enlargement driven by androgen signaling via disrupting mitochondrial function in mouse

The prostate is a vital accessory gonad in the mammalian male reproductive system. With the ever-increasing proportion of the population over 60 years of age worldwide, the incidence of prostate diseases, such as benign prostatic hyperplasia (BPH) and prostate cancer (PCa), is on the rise and is gradually becoming a significant medical problem globally. The notch signaling pathway is essential in regulating prostate early development. However, the potential regulatory mechanism of Notch signaling in prostatic enlargement and hyperplasia remains unclear. In this study, we proved that overactivation of Notch1 signaling in mouse prostatic epithelial cells (OEx) led to prostatic enlargement via enhancing proliferation and inhibiting apoptosis of prostatic epithelial cells. Further study showed that N1ICD/RBPJ directly up-regulated the androgen receptor (AR) and enhanced prostatic sensitivity to androgens. Hyper-proliferation was not found in orchidectomized OEx mice without androgen supply but was observed after Dihydrotestosterone (DHT) supplementation. Our data showed that the number of mitochondrion in prostatic epithelial cells of OEx mice was increased, but the mitochondrial function was impaired, and the essential activity of the mitochondrial respiratory electron transport chain was significantly weakened. Disordered mitochondrial number and metabolic function further resulted in excessive accumulation of reactive oxygen species (ROS). Importantly, anti-oxidant N-Acetyl-L-Cysteine (NAC) therapy could alleviate prostatic hyperplasia caused by the over-activation of Notch1 signaling. Furthermore, we observed the incremental Notch signaling activity in progenitor-like club cells in the scRNA-seq data set of human BPH patients. Moreover, the increased number of TROP2+ progenitors and Club cells was also confirmed in our OEx mice. In conclusion, our study revealed that over-activated Notch1 signaling induces prostatic enlargement by increasing androgen receptor sensitivity, disrupting cellular mitochondrial metabolism, increasing ROS, and a higher number of progenitor cells, all of which can be effectively rescued by NAC treatment.

A Review on Novel Applications of Nanotechnology in the Management of Prostate Cancer

BACKGROUND

Prostate cancer continues to be a serious danger to men's health, despite advances in the field of cancer nanotechnology. Although different types of cancer have been studied using nanomaterials and theranostic systems derived from nanomaterials, they have not yet reached their full potential for prostate cancer due to issues with in vivo biologic compatibility, immune reaction responses, accurate targetability, as well as a therapeutic outcome related to the nano-structured mechanism.

METHOD

The ultimate motive of this article is to understand the theranostic nanotechnology-based scheme for treating prostate cancer. The categorization of diverse nanomaterials in accordance with biofunctionalization tactics and biomolecule sources has been emphasized in this review so that they might potentially be used in clinical contexts and future advances. These opportunities can enhance the direct visualization of prostate tumors, early identification of prostate cancer-associated biomarkers at extremely low detection limits, and finally, the therapy for prostate cancer.

RESULT

In December 2022, a thorough examination of the scientific literature was carried out utilizing the Web of Science, PubMed, and Medline databases. The goal was to analyze novel applications of nanotechnology in the treatment of prostate cancer, together with their structural layouts and functionalities.

CONCLUSION

The various treatments and the reported revolutionary nanotechnology-based systems appear to be precise, safe, and generally successful; as a result, this might open up a new avenue for the detection and eradication of prostate cancer.

CYP19A1 is downregulated by BRD4 and suppresses castration-resistant prostate cancer cell invasion and proliferation by decreasing AR expression

Castration-resistant prostate cancer (CRPC) is the final stage of prostate cancer (PCa). As the main androgen in males, testosterone, and its androgen receptor (AR) play an important role in CRPC. The enzyme that catalyzes testosterone, aromatase, can be influenced by CYP19A1 activity - thus possibly affecting both AR expression and CRPC. However, the function of CYP19A1 in CRPC remains unclear. Using data derived from public databases and clinical samples, we analyzed the expression of CYP19A1 in PCa and CRPC specimens. The effect of CYP19A1 on cell invasion and proliferation was investigated in vitro and in vivo; while its function in metabolizing testosterone was detected in vitro. The effect of BRD4 on CYP19A1 and AR was investigated by qRT-PCR and western blot; whereas the effect of JQ1 on cells was assessed based on the IC50 value. We found that CYP19A1 was downregulated in CRPC samples and cells which correlated with a decrease in CRPC cell invasion and proliferation, and an increase in AR expression. Inversely, CYP19A1 affected CRPC cell invasion and proliferation by suppressing the expression of AR which may be attributed to the metabolism of testosterone by CYP19A1. Moreover, the BRD4 inhibitor JQ1 induced the CYP19A1 expression and suppressed the AR expression. Following BRD4 knockdown, CYP19A1 showed higher expression while AR expression was decreased. Our findings demonstrated that CYP19A1 could reduce CRPC cell invasion and proliferation by targeting AR, and this process could be regulated by BRD4. CYP19A1 may be a potential therapeutic target and enhance BRD4 inhibition in treating CRPC.

Strategies to Re-Sensitize Castration-Resistant Prostate Cancer to Antiandrogen Therapy

Since prostate cancer (PCa) was described as androgen-dependent, the androgen receptor (AR) has become the mainstay of its systemic treatment: androgen deprivation therapy (ADT). Although, through recent years, more potent drugs have been incorporated, this chronic AR signaling inhibition inevitably led the tumor to an incurable phase of castration resistance. However, in the castration-resistant status, PCa cells remain highly dependent on the AR signaling axis, and proof of it is that many men with castration-resistant prostate cancer (CRPC) still respond to newer-generation AR signaling inhibitors (ARSis). Nevertheless, this response is limited in time, and soon, the tumor develops adaptive mechanisms that make it again nonresponsive to these treatments. For this reason, researchers are focused on searching for new alternatives to control these nonresponsive tumors, such as: (1) drugs with a different mechanism of action, (2) combination therapies to boost synergies, and (3) agents or strategies to resensitize tumors to previously addressed targets. Taking advantage of the wide variety of mechanisms that promote persistent or reactivated AR signaling in CRPC, many drugs explore this last interesting behavior. In this article, we will review those strategies and drugs that are able to resensitize cancer cells to previously used treatments through the use of "hinge" treatments with the objective of obtaining an oncological benefit. Some examples are: bipolar androgen therapy (BAT) and drugs such as indomethacin, niclosamide, lapatinib, panobinostat, clomipramine, metformin, and antisense oligonucleotides. All of them have shown, in addition to an inhibitory effect on PCa, the rewarding ability to overcome acquired resistance to antiandrogenic agents in CRPC, resensitizing the tumor cells to previously used ARSis.

The Prevalence of CHEK1 and CHEK2 Mutations in Prostate Cancer: a Retrospective Cohort Study

Background

Prostate cancer (PCa) is one of the most common types of cancer among men. Mutations and accumulation of chromosomal deviations are correlated with the development and aggressiveness of PCa. Cell cycle checkpoint pathways and DNA repair mechanisms are reported to deviate in cancers. Mammalian checkpoint kinase 1/2 (CHEK1/CHEK2) genes act as key signal transducers inside the genomic integrity checkpoints. CHEK1 and CHEK2 gene mutations were reported in a few different types of cancers. In PCa, CHEK2 mutations were studied, but CHEK1 gene variations were not well investigated.

Objective

This study aimed to investigate the occurrence of variations in the CHEK1 and CHEK2 genes in PCa in the Jordanian population.

Methods

Formalin-fixed paraffin-embedded PCa specimens of radical prostatectomy surgical procedures from 74 Jordanian patients were subjected to DNA extraction, polymerase chain reactions and Sanger sequencing to screen the mutations in selected exons of CHEK1 and CHEK2 tumor suppressor genes.

Results

The presence of F281L (T/C) (1.4%) homologous missense point mutation in the kinase domain of the CHEK2 gene and P188P (1.4%) silent point mutation in the kinase domain of the CHEK1 gene. In addition, the 1100delC mutation was not detected in the studied PCa specimens.

Conclusion

In line with previous reports, the presence of CHEK2 mutation with a frequency of 1.4% supported the possible role of genetic variants of this gene in the development of PCa. No 1100delC mutation was detected in this study. No association was found in this study between CHEK1 mutations and the development of PCa. Further studies are needed with larger cohorts along with a screening of more exons in order to shed more light on the frequency of CHEK2 gene mutations and their role in the development of PCa in Jordan.

Prostate cancer in transgender women: considerations for screening, diagnosis and management

Transgender individuals represent 0.55% of the US population, equivalent to 1.4 million transgender adults. In transgender women, feminisation can include a number of medical and surgical interventions. The main goal is to deprive the phenotypically masculine body of androgens and simultaneously provide oestrogen therapy for feminisation. In gender-confirming surgery (GCS) for transgender females, the prostate is usually not removed. Due to limitations of existing cohort studies, the true incidence of prostate cancer in transgender females is unknown but is thought to be less than the incidence among cis-gender males. It is unclear how prostate cancer develops in androgen-deprived conditions in these patients. Six out of eleven case reports in the literature presented with metastatic disease. It is thought that androgen receptor-mediated mechanisms or tumour-promoting effects of oestrogen may be responsible. Due to the low incidence of prostate cancer identified in transgender women, there is little evidence to drive specific screening recommendations in this patient subpopulation. The treatment of early and locally advanced prostate cancer in these patients warrants an individualised thoughtful approach with input from patients' reconstructive surgeons. Both surgical and radiation treatment for prostate cancer in these patients can profoundly impact the patient's quality of life. In this review, we discuss the evidence surrounding screening and treatment of prostate cancer in transgender women and consider the current gaps in our knowledge in providing evidence-based guidance at the molecular, genomic and epidemiological level, for clinical decision-making in the management of these patients.

Intracellular distribution of vinclozolin and its metabolites differently affects 5α-dihydrotestosterone (DHT)-induced PSA secretion in LNCaP cells

Endocrine disruption mechanisms in prostate are an overlooked issue. The anti-androgenic properties of the fungicide vinclozolin (VIN) and its active metabolites - 2-[[(3,5- dichlorophenyl)-carbamoyl]oxy]-2-methyl-3-butenoic acid (M1) and 3'5'-dichloro-2-hydroxy-2- methylbut-3-enanilide (M2) - were assessed on human prostate-derived cells (LNCaP); the effects were investigated also upon co-treatment with 5α-dihydrotestosterone (DHT), the physiological androgen receptor (AR)-agonist, and compared to the anti-androgenic drugs, 2-hydroxy-flutamide (2OH-FTA) and bicalutamide (BIC). Assessed endpoints were the cellular uptake and subcellular localization of VIN, M1 and M2, DHT-induced PSA gene expression and secretion. VIN, its metabolites, and the reference drugs, significantly reduced DHT-induced PSA secretion and gene expression, M2 showing the strongest downregulation. In absence of DHT, 2OH-FTA and BIC showed a very high (>98%) LNCaP uptake with a predominant intranuclear localization (BIC=80%, 2OH-FTA=70%). VIN cellular uptake was 42%: 24.7% made up by M2, mostly localized at nuclear level, differently from VIN and M1. Upon DHT co-treatment, VIN intracellular uptake increased by 28%, especially in the microsomal fraction (MF); M2 also increased mainly in MF but also, to a lower extent, in the intranuclear fraction. Finally, in a 72-hr time-course, the LNCaP uptake of VIN and its metabolites was much faster compared to purified M1 and M2. Overall, M2 resulted the leading compound for VIN endocrine-disrupting effects in LNCaP.

Computational approaches for evaluation of isobavachin as potential inhibitor against t877a and w741l mutations in prostate cancer

Prostate cancer is the World's second most common cancer, with the fifth-highest male mortality rate. Point mutations such as T877A and W741L are frequently seen in advanced prostate cancer patients, conferring drug-resistance and hence driving cancer growth. Such occurrence of drug resistance in prostate cancer necessitates designing of suitable ligands to ensure better interactions with the receptors which can block the progression of the disease. The present study focus on the modification of plant-derived flavonoids that might act as inhibitors against such point mutations namely, T877A and W741L. In T877A mutation threonine is substituted by alanine at the 877 codon and W741L mutation, tryptophan is substituted by lysine at the 741 codon in prostate cancer. The study revolved on the aspect of the evaluation of Isobavachin and its derivatives as a potential agent to tackle such point mutations by using the in silico approach. A total of 98 molecular dockings were performed to find the ligand-receptor complexes with the lowest binding energy employing Autodock Software to conduct the blind and site-specific docking. Additionally, ligands were screened for Drug-likeness and toxicity using several tools yielding eight possible drug candidates. Based on the results of Molecular Docking, Drug-likeness, and ADMET testing, ten structures, including six complexes and three receptors were subjected to molecular dynamics simulation of 100 ns covering RMSD, RMSF, Rg, and MM/PBSA. Based on the simulation results, Isobavachin, IsoMod4, and IsoMod7 were concluded to be stable and exhibited potential properties for developing a novel drug to combat prostate cancer and its associated drug-resistance.

Androgen receptor regulates eIF5A2 expression and promotes prostate cancer metastasis via EMT

Androgen receptor (AR) is an androgen-activated transcription factor of the nuclear receptor superfamily. AR plays a role in the development and progression of prostate cancer (PCa). However, the exact role of AR in PCa metastasis remains unclear. In the present study, we aimed to elucidate the function of AR in PCa. We found that eukaryotic translation initiation factor (EIF) 5A2, an elongation factor that induces epithelial-to-mesenchymal transition (EMT) in PCa cells, was significantly upregulated after 5α-dihydrotestosterone (DHT) stimulation and downregulated after anti‐androgen bicalutamide treatment in PCa cells with high AR expression, but not in cells with low AR expression. Moreover, eIF5A2 knockdown could eliminate DHT-induced invasion and migration of AR-positive PCa cells. DHT treatment decreased epithelial expression of E‐cadherin and β-catenin but increased the expression of the mesenchymal marker proteins Vimentin and N-cadherin. DHT therefore induced EMT, and knockdown of eIF5A2 inhibited DHT-induced EMT. Moreover, in vivo study, Luciferase signals from the lungs of the eIF5A2 plasmid group indicated higher metastasis ability, and the eIF5A2 siRNA group had lower metastasis ability. Our results suggest that AR positively regulates eIF5A2 expression in androgen-dependent cells, and stimulation of AR expression and signaling in prostate tumors promotes PCa metastasis by EMT induction and upregulation of eIF5A2.

Proteomic Analysis Identifies NDUFS1 and ATP5O as Novel Markers for Survival Outcome in Prostate Cancer

Simple Summary

Due to the heterogeneity of prostate cancer (PCa), it is still difficult to provide risk stratification. Metabolic changes in PCa tissue have been described during tumor progression at genetic and transcriptomic level, but these have not yet clearly contributed to improved diagnosis and therapy. The aim of our study was to identify novel markers for aggressive prostate cancer in a proteomics-derived dataset by immunohistochemical analysis and correlation with transcriptomic data. Here, we provide potential new markers—NDUFS1 and ATP5O—for risk stratification in PCa. Additionally, we reveal for the first time a concordant increase of NDUFS1/ATP5O of mRNA expression in transcriptomic datasets and at protein level.

Abstract

We aimed to identify novel markers for aggressive prostate cancer in a STAT3-low proteomics-derived dataset of mitochondrial proteins by immunohistochemical analysis and correlation with transcriptomic data and biochemical recurrence in a STAT3 independent PCa cohort. Formalin-fixed paraffin-embedded tissue (FFPE) sample selection for proteomic analysis and tissue-microarray (TMA) generation was conducted from a cohort of PCa patients. Retrospective data analysis was performed with the same cohort. 153 proteins differentially expressed between STAT3-low and STAT3-high samples were identified. Out of these, 46 proteins were associated with mitochondrial processes including oxidative phosphorylation (OXPHOS), and 45 proteins were upregulated, including NDUFS1/ATP5O. In a STAT3 independent PCa cohort, high expression of NDUFS1/ATP5O was confirmed by immunocytochemistry (IHC) and was significantly associated with earlier biochemical recurrence (BCR). mRNA expression levels for these two genes were significantly higher in intra-epithelial neoplasia and in PCa compared to benign prostate glands. NDUFS1/ATP5O levels are increased both at the mRNA and protein level in aggressive PCa. Our results provide evidence that NDUFS1/ATP5O could be used to identify high-risk PCa patients.

Multifunctionality of prostatic acid phosphatase in prostate cancer pathogenesis

The role of human prostatic acid phosphatase (PAcP, P15309|PPAP_HUMAN) in prostate cancer was investigated using a new proteomics tool termed signal sequence swapping (replacement of domains from the native cleaved amino terminal signal sequence of secretory/membrane proteins with corresponding regions of functionally distinct signal sequence subtypes). This manipulation preferentially redirects proteins to different pathways of biogenesis at the endoplasmic reticulum (ER), magnifying normally difficult to detect subsets of the protein of interest. For PAcP, this technique reveals three forms identical in amino acid sequence but profoundly different in physiological functions, subcellular location, and biochemical properties. These three forms of PAcP can also occur with the wildtype PAcP signal sequence. Clinical specimens from patients with prostate cancer demonstrate that one form, termed ^PLPAcP, correlates with early prostate cancer. These findings confirm the analytical power of this method, implicate ^PLPAcP in prostate cancer pathogenesis, and suggest novel anticancer therapeutic strategies.

A Review of the Pathophysiological Mechanisms Underlying Castration-resistant Prostate Cancer

Androgen deprivation therapy or ADT is one of the cornerstones of management of locally advanced or metastatic prostate cancer, alongside radiation therapy. However, despite early response, most advanced prostate cancers progress into an androgen unresponsive or castrate resistant state, which hitherto remains an incurable entity and the second leading cause of cancer-related mortality in men in the US. Recent advances have uncovered multiple complex and intermingled mechanisms underlying this transformation. While most of these mechanisms revolve around androgen receptor (AR) signaling, novel pathways which act independently of the androgen axis are also being discovered. The aim of this article is to review the pathophysiological mechanisms that help bypass the apoptotic effects of ADT to create castrate resistance. The article discusses castrate resistance mechanisms under two categories: 1. Direct AR dependent pathways such as amplification or gain of function mutations in AR, development of functional splice variants, posttranslational regulation, and pro-oncogenic modulation in the expression of coactivators vs corepressors of AR. 2. Ancillary pathways involving RAS/MAP kinase, TGF-beta/SMAD pathway, FGF signaling, JAK/STAT pathway, Wnt-Beta catenin and hedgehog signaling as well as the role of cell adhesion molecules and G-protein coupled receptors. miRNAs are also briefly discussed. Understanding the mechanisms involved in the development and progression of castration-resistant prostate cancer is paramount to the development of targeted agents to overcome these mechanisms. A number of targeted agents are currently in development. As we strive for more personalized treatment across oncology care, treatment regimens will need to be tailored based on the type of CRPC and the underlying mechanism of castration resistance.

Prostatic basal cell carcinoma treated by chemoradiation with weekly cisplatine: case report and literature review

Background

Basal cell carcinoma of the prostate is a relatively rare entity. Their evolution is characterized by the frequency of local and/or distant relapses. Due to their rarity, the treatment is not consensual in the literature. We report here a case of Basal cell carcinoma of the prostate in a 40-year-old patient.

Case presentation

Our patient initially presented an obstructive lower urinary tract symptoms with a normal initial level of prostate specific antigen (PSA) test (3.5 ng/m). The transurethral resection of the prostate (TURP) was in favor of a prostatic basal cell carcinoma with its specific anatomopathological and immunohistochemical characteristics. The prostatic MRI and thoraco-abdominal CT realized after the TURP revealed a tumoral lesion of the prostatic peripheral zone with extra-capsular extension combined with right seminal vesicle invasion and a suggestion of posterior bladder wall adherence. No evidence of visceral or nodal metastases at this point. Considering the tumor being locally advanced, a concurrent chemoradiotherapy with intensity modulated technique was indicated after a multidisciplinary meeting with a 70 Gy total target dose delivered in 35 fractions and weekly Cisplatin. A year and a half after, he developed a cerebellous metastases revealed by intracranial hypertension with no other visceral lesion and complete local remission with the disappearance of the lower urinary tract symptoms and the pain and the appearance of a prostatic atrophy. The PSA level was still on the upper limit of normal. He underwent metastasectomy, and the anatomopathological study was in favor of a cerebellous metastasis of the known BCC. The patient presented postoperatively paraparesis of lower limbs with balance problems for which he was placed in palliative care with indication of postoperative radiation therapy in case of improvement of his general condition. He did not recover and deceased three months later.

Conclusions

The prostatic basal cell carcinoma is a rare aggressive entity often non-evoked at the clinical or radiological stages because of its unspecific appearance. The diagnostic of these tumors is based on histological examination and a large immunohistochemistry panel. Given its scarity, very few data is available for locally advanced non-metastatic stages treated by radiation therapy. We assess here a good local response with concurrent chemoradiation therapy.

Oxidative stress and redox signaling in CRPC progression: therapeutic potential of clinically-tested Nrf2-activators

Androgen deprivation therapy (ADT) is the mainstay regimen in patients with androgen-dependent prostate cancer (PCa). However, the selection of androgen-independent cancer cells leads to castrate resistant prostate cancer (CRPC). The aggressive phenotype of CRPC cells underscores the need to elucidate mechanisms and therapeutic strategies to suppress CRPC outgrowth. Despite ADT, the activation of androgen receptor (AR) transcription factor continues via crosstalk with parallel signaling pathways. Understanding of how these signaling cascades are initiated and amplified post-ADT is lacking. Hormone deprivation can increase oxidative stress and the resultant reactive oxygen species (ROS) may activate both AR and non-AR signaling. Moreover, ROS-induced inflammatory cytokines may further amplify these redox signaling pathways to augment AR function. However, clinical trials using ROS quenching small molecule antioxidants have not suppressed CRPC progression, suggesting that more potent and persistent suppression of redox signaling in CRPC cells will be needed. The transcription factor Nrf2 increases the expression of numerous antioxidant enzymes and downregulates the function of inflammatory transcription factors, e.g., nuclear factor kappa B. We documented that Nrf2 overexpression can suppress AR-mediated transcription in CRPC cell lines. Furthermore, two Nrf2 activating agents, sulforaphane (a phytochemical) and bardoxolone-methyl (a drug in clinical trial) suppress AR levels and sensitize CRPC cells to anti-androgens. These observations implicate the benefits of potent Nrf2-activators to suppress the lethal signaling cascades that lead to CRPC outgrowth. This review article will address the redox signaling networks that augment AR signaling during PCa progression to CRPC, and the possible utility of Nrf2-activating agents as an adjunct to ADT.

Signalling transduction of O-GlcNAcylation and PI3K/AKT/mTOR-axis in prostate cancer

Hexosamine biosynthetic (HBP) and PI3K/AKT/mTOR pathways are found to predominate the proliferation and survival of prostate cancer cells. Both these pathways have their own specific intermediates to propagate the secondary signals in down-stream cascades and besides having their own structured network, also have shared interconnecting branches. These interconnections are either competitive or co-operative in nature depending on the microenvironmental conditions. Specifically, in prostate cancer HBP and mTOR pathways increases the expression and protein level of androgen receptor in order to support cancer cell proliferation, advancement and metastasis. Pharmacological inhibition of a single pathway is therefore insufficient to stop disease progression as the cancer cells manage to alter the signalling channel. This is one of the primary reasons for the therapeutic failure in prostate cancer and emergence of chemoresistance. Inhibition of these multiple pathways at their common junctures might prove to be of benefit in men suffering from an advanced disease state. Hence, a thorough understanding of these cellular intersecting points and their significance with respect to signal transduction mechanisms might assist in the rational designing of combinations for effective management of prostate cancer.

Resistance to Androgen Deprivation Leads to Altered Metabolism in Human and Murine Prostate Cancer Cell and Tumor Models

Currently, no clinical methods reliably predict the development of castration-resistant prostate cancer (CRPC) that occurs almost universally in men undergoing androgen deprivation therapy. Hyperpolarized (HP) ¹³C magnetic resonance imaging (MRI) could potentially detect the incipient emergence of CRPC based on early metabolic changes. To characterize metabolic shifts occurring upon the transition from androgen-dependent to castration-resistant prostate cancer (PCa), the metabolism of [U-¹³C]glucose and [U-¹³C]glutamine was analyzed by nuclear magnetic resonance spectroscopy. Comparison of steady-state metabolite concentrations and fractional enrichment in androgen-dependent LNCaP cells and transgenic adenocarcinoma of the murine prostate (TRAMP) murine tumors versus castration-resistant PC-3 cells and treatment-driven CRPC TRAMP tumors demonstrated that CRPC was associated with upregulation of glycolysis, tricarboxylic acid metabolism of pyruvate; and glutamine, glutaminolysis, and glutathione synthesis. These findings were supported by ¹³C isotopomer modeling showing increased flux through pyruvate dehydrogenase (PDH) and anaplerosis; enzymatic assays showing increased lactate dehydrogenase, PDH and glutaminase activity; and oxygen consumption measurements demonstrating increased dependence on anaplerotic fuel sources for mitochondrial respiration in CRPC. Consistent with ex vivo metabolomic studies, HP [1-¹³C]pyruvate distinguished androgen-dependent PCa from CRPC in cell and tumor models based on significantly increased HP [1-¹³C]lactate.

Computational Assessment of Combination Therapy of Androgen Receptor-Targeting Compounds

The ligand-binding domain of the androgen receptor (AR) is a target for drugs against prostate cancer and offers three distinct binding sites for small molecules. Drugs acting on the orthosteric hormone binding site suffer from resistance mechanisms that can, in the worst case, reverse their therapeutic effect. While many allosteric ligands targeting either the activation function-2 (AF-2) or the binding function-3 (BF-3) have been reported, their potential for simultaneous administration with currently prescribed antiandrogens was disregarded. Here, we report results of 60 μs molecular dynamics simulations to investigate combinations of orthosteric and allosteric AR antagonists. Our results suggest BF-3 inhibitors to be more suitable in combination with classical antiandrogens as opposed to AF-2 inhibitors based on binding free energies and binding modes. As a mechanistic explanation for these observations, we deduced a structural adaptation of helix-12 involved in the formation of the AF-2 site by classical AR antagonists. Additionally, the changes were accompanied by an expansion of the orthosteric binding site. Considering our predictions, the selective combination of AR-targeting compounds may improve the treatment of prostate cancer.

KDM6B is an androgen regulated gene and plays oncogenic roles by demethylating H3K27me3 at cyclin D1 promoter in prostate cancer

Lysine (K)-specific demethylase 6B (KDM6B), a stress-inducible H3K27me3 demethylase, plays oncogenic or antitumoral roles in malignant tumors depending on the type of tumor cell. However, how this histone modifier affects the progression of prostate cancer (PCa) is still unknown. Here we analyzed sequenced gene expression data and tissue microarray to explore the expression features and prognostic value of KDM6B in PCa. Further, we performed in vitro cell biological experiments and in vivo nude mouse models to reveal the biological function, upstream and downstream regulation mechanism of KDM6B. In addition, we investigated the effects of a KDM6B inhibitor, GSK-J4, on PCa cells. We showed that KDM6B overexpression was observed in PCa, and elevated KDM6B expression was associated with high Gleason Score, low serum prostate-specific antigen level and shorted recurrence-free survival. Moreover, KDM6B prompted proliferation, migration, invasion and cell cycle progression and suppressed apoptosis in PCa cells. GSK-J4 administration could significantly suppress the biological function of KDM6B in PCa cells. KDM6B is involved in the development of castration-resistant prostate cancer (CRPC), and combination of MDV3100 plus GSK-J4 is effective for CRPC and MDV3100-resistant CRPC. Mechanism exploration revealed that androgen receptor can decrease the transcription of KDM6B and that KDM6B demethylates H3K27me3 at the cyclin D1 promoter and cooperates with smad2/3 to prompt the expression of cyclin D1. In conclusion, our study demonstrates that KDM6B is an androgen receptor regulated gene and plays oncogenic roles by promoting cyclin D1 transcription in PCa and GSK-J4 has the potential to be a promising agent for the treatment of PCa.

Upregulation of potential regulatory signaling molecules correlate with androgen receptor splice variants AR-V7 and AR-V567es in prostate cancer metastasis

AIM

Androgen receptor splice variants (AR-Vs) produced by alternative splicing of the AR play an important role in the treatment resistance and progression of prostate cancer (PCa). In this study, two most common AR variants and how they associate with the inflammatory response (NF-Kβ) and regulatory transcriptional activity (HSP-27) genes were investigated in patients with PCa and metastatic PCa (Met-PCa).

METHODS

Our study was carried out with the whole blood obtained from 25 healthy control subjects, 25 PCa patients and 39 Met-PCa patients. We examined the expression levels of AR, AR-V7 and AR-V567es genes via Real-time PCR and those of HSP-27 and NF-Kβ via ELISA method.

RESULTS

AR, AR-V7 and AR-V567es expressions were observed in 84.61%, 64.1%, 23.07% of Met-PCa patients respectively. The expression levels of full-length AR and variants (AR-V7 and AR-V567es) were associated with the prostate cancer stage. In the Met-PCa, the expression levels of AR, AR-V7 and AR-V567es were associated with the Gleason Scores but not with the PSA levels. AR-V7 expression levels in stage T4 patients significantly increased. NF-Kβ and HSP-27 protein levels were significantly higher in Met-PCa patients.

DISCUSSION

Our findings highlight the targeting of the proteostasis and inflammation pathways through inhibiting HSP-27 and NF-Kβ. This might be a valuable strategy to overcome anti-androgen resistance and improve drug therapy in Met-PCa patients whose gene expression levels of AR-V7 and AR-V567es variants are high.

Involvement of the MEN1 Gene in Hormone-Related Cancers: Clues from Molecular Studies, Mouse Models, and Patient Investigations

MEN1 mutation predisposes patients to multiple endocrine neoplasia type 1 (MEN1), a genetic syndrome associated with the predominant co-occurrence of endocrine tumors. Intriguingly, recent evidence has suggested that MEN1 could also be involved in the development of breast and prostate cancers, two major hormone-related cancers. The first clues as to its possible role arose from the identification of the physical and functional interactions between the menin protein, encoded by MEN1, and estrogen receptor α and androgen receptor. In parallel, our team observed that aged heterozygous Men1 mutant mice developed cancerous lesions in mammary glands of female and in the prostate of male mutant mice at low frequencies, in addition to endocrine tumors. Finally, observations made both in MEN1 patients and in sporadic breast and prostate cancers further confirmed the role played by menin in these two cancers. In this review, we present the currently available data concerning the complex and multifaceted involvement of MEN1 in these two types of hormone-dependent cancers.

Signaling through estrogen receptors modulates long non-coding RNAs in prostate cancer

Prostate cancer (PCa) is a sex-steroid hormone-dependent cancer in which estrogens play a critical role in both initiation and progression. Recently, several long non-coding RNAs (lncRNAs) have been associated with PCa and are supposedly playing a pivotal role in the biology and progression of this type of cancer. In this review, we focused on some lncRNAs that are known for their androgen and estrogen transcriptional responsiveness in PCa. Specifically, we summarized recent pieces of evidence about lncRNAs NEAT1, H19, MALAT1, and HOTAIR, in estrogen signaling, emphasizing their role in PCa progression and the acquisition of a castration-resistant phenotype. Here, the reader will find information about lncRNAs present in estrogen-dependent transcriptional complexes. The potential role of lncRNA/estrogen signaling as a novel pathway for PCa treatment will be discussed.

Ailanthone: A novel potential drug for treating human cancer

Cancer is the second leading cause of death after cardiovascular disease. In 2015, >8.7 million people died worldwide due to cancer, and by 2030 this figure is expected to increase to ~13.1 million. Tumor chemotherapy drugs have specific toxicity and side effects, and patients can also develop secondary drug resistance. To prevent and treat cancer, scientists have developed novel drugs with improved antitumor effects and decreased toxicity. Ailanthone (AIL) is a quassinoid extract from the traditional Chinese medicine plant Ailanthus altissima, which is known to have anti-inflammatory and antimalarial effects. An increasing number of studies have focused on AIL due to its antitumor activity. AIL can inhibit cell proliferation and induce apoptosis by up- or downregulating cancer-associated molecules, which ultimately leads to cancer cell death. Antitumor effects of AIL have been observed in melanoma, acute myeloid leukemia, bladder, lung, breast, gastric and prostate cancer and vestibular neurilemmoma. To the best of our knowledge, the present study is the first review to describe the antitumor mechanisms of AIL.

Quantitative Evaluation of the Transcriptional Activity of Steroid Hormone Receptor Mutants and Variants Using a Single Vector With Two Reporters and a Receptor Expression Cassette

Although the rapid development of high-throughput sequencing has led to the identification of a large number of truncated or mutated steroid hormone receptor (SHR) variants, their clinical relevance remains to be defined. A platform for functional analysis of these SHR variants in cells would be instrumental for better assessing their impact on normal physiology and SHR-associated diseases. Here we have developed a new reporter system that allows rapid and accurate assessment of the transcriptional activity of SHR variants in cells. The reporter is a single construct containing a firefly luciferase reporter gene, whose expression is under the control of a promoter with multiple steroid hormone responsive elements, and a Renilla luciferase reporter gene, that is constitutively expressed under the control of an internal ribosome entry site (IRES) and is not regulated by steroid hormones. The corresponding SHR (wildtype or mutant/variant) is also expressed from the same construct. Using this improved reporter system, we revealed a large spectrum of transactivation activities within a set of previously identified mutations and variations of the androgen receptor (AR), the estrogen receptor α (ERα) and the glucocorticoid receptor (GR). This novel reporter system enables functional analysis of SHR mutants and variants in physiological and pathological settings, offering valuable preclinical, or diagnostic information for the understanding and treatment of associated diseases.

The Prospect of Identifying Resistance Mechanisms for Castrate-Resistant Prostate Cancer Using Circulating Tumor Cells: Is Epithelial-to-Mesenchymal Transition a Key Player?

Prostate cancer (PCa) is initially driven by excessive androgen receptor (AR) signaling with androgen deprivation therapy (ADT) being a major therapeutic approach to its treatment. However, the development of drug resistance is a significant limitation on the effectiveness of both first-line and more recently developed second-line ADTs. There is a need then to study AR signaling within the context of other oncogenic signaling pathways that likely mediate this resistance. This review focuses on interactions between AR signaling, the well-known phosphatidylinositol-3-kinase/AKT pathway, and an emerging mediator of these pathways, the Hippo/YAP1 axis in metastatic castrate-resistant PCa, and their involvement in the regulation of epithelial-mesenchymal transition (EMT), a feature of disease progression and ADT resistance. Analysis of these pathways in circulating tumor cells (CTCs) may provide an opportunity to evaluate their utility as biomarkers and address their importance in the development of resistance to current ADT with potential to guide future therapies.

KLF5 Is Crucial for Androgen-AR Signaling to Transactivate Genes and Promote Cell Proliferation in Prostate Cancer Cells

Androgen/androgen receptor (AR) signaling drives both the normal prostate development and prostatic carcinogenesis, and patients with advanced prostate cancer often develop resistance to androgen deprivation therapy. The transcription factor Krüppel-like factor 5 (KLF5) also regulates both normal and cancerous development of the prostate. In this study, we tested whether and how KLF5 plays a role in the function of AR signaling in prostate cancer cells. We found that KLF5 is upregulated by androgen depending on AR in LNCaP and C4-2B cells. Silencing KLF5, in turn, reduced AR transcriptional activity and inhibited androgen-induced cell proliferation and tumor growth in vitro and in vivo. Mechanistically, KLF5 occupied the promoter of AR, and silencing KLF5 repressed AR transcription. In addition, KLF5 and AR physically interacted with each other to regulate the expression of multiple genes (e.g., MYC, CCND1 and PSA) to promote cell proliferation. These findings indicate that, while transcriptionally upregulated by AR signaling, KLF5 also regulates the expression and transcriptional activity of AR in androgen-sensitive prostate cancer cells. The KLF5-AR interaction could provide a therapeutic opportunity for the treatment of prostate cancer.

Identification of key genes and multiple molecular pathways of metastatic process in prostate cancer

Background

Cancer metastasis is well known as the most adverse outcome and the major cause of mortality in cancer patients, including prostate cancer (PCa). There are no credible predictors, to this day, that can reflect the metastatic ability of localized PCa. In the present study, we firstly identified the differentially expressed genes (DEGs) and molecular pathways involved in the metastaic process of PCa by comparing gene expressions of metastaic PCa with localized PCa directly, with the purpose of identifying potential markers or therapeutic targets.

Methods

The gene expression profiles (GSE6919 and GSE32269) were downloaded from the Gene Expression Omnibus database, which contained 141 tissue samples, including 87 primary localized PCa samples and 54 metastaic PCa samples. After data processing, DEGs were identified by R language using the Student’s t-test adjusted via the Beniamini–Hochberg method. Subsequently, the gene ontology functional and pathway enrichment analyses of DEGs were performed and the protein–protein interaction network was constructed. Hub genes were identified using the plug-in cytoHubba in Cytoscape software by MCC and degree. Furthermore, validation and prognostic significance analysis of the hub genes were performed by UALCAN and gene expression profiling interactive analysis (GEPIA).

Results

A total of 90 DEGs were identified between localized and metastaic PCa, which consisted of 47 upregulated and 43 downregulated genes. The enriched functions and pathways of the DEGs include catabolic process, cell cycle, response to steroid hormone, extracellular matrix (ECM)-receptor interaction and vascular smooth muscle contraction. A total of 10 genes were identified as hub genes and biological process analysis of hub genes showed that cell cycle phase, cell division, and mitotic cell cycle process were mainly enriched. The expression of hub genes were confirmed in metastaic PCa when compared with localized PCa tissues by The Cancer Genome Atlas database. Moreover, the disease-free survival analysis of hub genes revealed that these genes may play an important role in invasion, progression or recurrence. Therefore, these hub genes might be the key genes contributed to tumor progression or metastasis in PCa and provide candidate therapeutic targets for PCa.

Conclusions

The present study identified some DEGs between localized and metastaic PCa tissue samples. These key genes might be potential therapeutic targets and biomarkers for the metastaic process of PCa.

MicroRNA biogenesis, gene silencing mechanisms and role in breast, ovarian and prostate cancer

Micro-ribonucleic acids (miRNAs) are important class of short regulatory RNA molecules involved in regulation of several essential biological processes. In addition to Dicer and Drosha, over the past few years several other gene products are discovered that regulates miRNA biogenesis pathways. Similarly, various models of molecular mechanisms underlying miRNA mediated gene silencing have been uncovered through which miRNA contribute in diverse physiological and pathological processes. Dysregulated miRNA expression has been reported in many cancers manifesting tumor suppressive or oncogenic role. In this review, critical overview of recent findings in miRNA biogenesis, silencing mechanisms and specifically the role of miRNA in breast, ovarian and prostate cancer will be described. Recent advancements in miRNA research summarized in this review will enhance the molecular understanding of miRNA biogenesis and mechanism of action. Also, role of miRNAs in pathogenesis of breast, ovarian and prostate cancer will provide the insights for the use of miRNAs as biomarker or therapeutic agents for the cancers.

MicroRNA-381 suppresses proliferation and invasion of prostate cancer cells through downregulation of the androgen receptor

Prostate cancer (PCa) is the most frequently diagnosed malignancy in men and its incidence has increased rapidly worldwide. Notably, the molecular mechanisms underlying prostate tumorigenesis have not been fully identified. The levels of microRNA (miR)-381 have been explored in numerous types of malignancy; however, the expression levels and biological function of miR-381 in PCa remain largely unknown. In the present study, reverse-transcription polymerase chain reaction was used to detect the expression levels of miR-381 in PCa cells and normal prostate epithelial cells. Subsequently, miR-381 antisense oligonucleotides and mimics were transfected into LNCaP PCa cells. Bioinformatics analysis was performed to identify the potential target genes of miR-381. Protein expression analysis, dual-luciferase reporter assay and a rescue assay were used to confirm the target of miR-381. The data suggested that the expression levels of miR-381 were significantly decreased in PCa cells compared with in normal prostatic epithelial cells. Furthermore, transfection of LNCaP cells with miR-381 mimics suppressed their proliferation, migration and invasion. In addition, bioinformatics analysis suggested that the androgen receptor (AR) was a target gene of miR-381. miR-381 suppressed the expression levels of AR by directly binding to its 3'-untranslated region. Furthermore, transfection with an AR plasmid partially attenuated miR-381-induced inhibition of cell proliferation, migration and invasion. The results of the present study suggested that miR-381 may act as a tumor suppressor in PCa by directly targeting the AR.

Androgen receptor: what we know and what we expect in castration-resistant prostate cancer

Androgen deprivation therapy is an important therapy for prostate cancer (PCa) in aging men. Under the background of castration, it is inevitable that prostate cancer will develop into castration-resistant prostate cancer (CRPC), which has a high mortality rate, after 2-3 years. Androgen receptor (AR) plays a key role in PCa development and is essential to CRPC. More recent research studies have reported that the development of CRPC is largely due to altered mechanisms related to AR, so it is important for us to understand the roles of AR and detailed AR-related mechanisms in CRPC. The multiple AR-related mechanisms promoting the development of CRPC are as follows: (1) enhanced transformation and increased synthesis of intratumoral androgen; (2) AR overexpression, which enables CRPC to be hypersensitive to low levels of androgen; (3) AR cofactors, which enhanced AR transactivation; (4) AR-spliced variants, which mediated downstream gene expression without androgen; (5) the interaction between the AR pathway and classic tumor-related pathways; and» (6) AR mutations, which reduced AR specificity and enhanced AR transcription.

Current status of androgen receptor-splice variant 7 inhibitor niclosamide in castrate-resistant prostate-cancer

Castrate-Resistant Prostate-Cancer (CRPC) is one of the most common malignancies occurring in men. Unfortunately, even if several recently approved agents clinically improved the outcome of CRPC patients, none of these is curative especially for a splice version of the Androgen Receptor (AR) AR-V7, which is a variant of the receptor constitutively activated and does not require the presence of androgens for the activation AR down-stream pathways. Since high AR-V7 expression is one of the most common features of CRPC, targeting this receptor variant is considered as one of the most promising strategies for treating this disease. Therefore anti-AR-V7 molecules could lead to a potential shift in paradigm in the treatment of CRPC. Niclosamide, an already FDA-approved anti-helminthic drug, was identified as a potent AR-V7 inhibitor in prostate cancer cells. Due to the recent positive preclinical results, niclosamide may be an interesting and novel type of targeted treatments for CRPC. This mini-review outlines the most recent pre- and clinical- data on the current status of niclosamide in the treatment of ARV7-positive CRPC patients.

Androgen receptor mediated epigenetic regulation of CRISP3 promoter in prostate cancer cells

Cysteine-rich secretory protein 3 (CRISP3) is one of the most upregulated genes in prostate cancer. Androgen receptor (AR) plays an important role not only in initial stages of prostate cancer development but also in the advanced stage of castration-resistant prostate cancer (CRPC). Role of AR in regulation of CRISP3 expression is not yet known. In order to understand the regulation of CRISP3 expression, various overlapping fragments of CRISP3 promoter were cloned in pGL3 luciferase reporter vector. All constructs were transiently and stably transfected in PC3 (CRISP3 negative) and LNCaP (CRISP3 positive) cell lines and promoter activity was measured by luciferase assay. Promoter activity of LNCaP stable clones was significantly higher than PC3 stable clones. Further in CRISP3 negative PC3 and RWPE-1 cells, CRISP3 promoter was shown to be silenced by histone deacetylation. Treatment of LNCaP cells with DHT resulted in increase in levels of CRISP3 transcript and protein. AR dependency of CRISP3 promoter was also evaluated in LNCaP stable clones by luciferase assay. To provide molecular evidence of epigenetic regulation of CRISP3 promoter and its response to DHT, ChIP PCR was performed in PC3 and LNCaP cells. Our results demonstrate that CRISP3 expression in prostate cancer cells is androgen dependent and in AR positive cells, CRISP3 promoter is epigenetically regulated by AR.

Treatment-induced changes in the androgen receptor axis: Liquid biopsies as diagnostic/prognostic tools for prostate cancer

Prostate cancer progression and treatment relapse is associated with changes in the androgen receptor axis, and analysis of alternations of androgen receptor signaling is valuable for prognostics and treatment optimization. The profile of androgen receptor axis is currently obtained from biopsy specimens, which are not always easy to obtain. Moreover, the information acquired only provides a snapshot of the tumor biology, with strict spatial and temporal limitations. On the other hand, circulation is easily accessible source of both circulating tumor cells and circulating tumor DNA, which can be sampled at numerous time points. This Review will explore the potential use of androgen receptor axis alternations detectable in the blood in therapeutic decision-making and precision medicine for advancing metastatic castration-resistant prostate cancer.

Germline Mutations and Polymorphisms of Androgen Receptor in Prostate Cancer Patients: Frequency and Results of in Silico Analysis

Background: Germline and somatic polymorphisms and mutations of the Androgen Receptor (AR) gene are known to be associated with the incidence of prostate cancer (PCa) in different populations. In this study we assessed germline AR polymorphisms and mutations in PCa patients with prediction of pathogenicity of the identified mutations by in silico analysis. Methods: Diagnosis of PCa was based on histopathology of prostate tissue (Gleason Score criteria) and serum prostate-specific antigen (PSA) levels. Genomic DNA was extracted from peripheral blood of 38 patients. All exons and exon-intron boundaries of AR were amplified using polymerase chain reactions (PCR) followed by Sanger sequencing. In silico analysis was performed using Polyphen-2 and Mutation Taster®. Results: Two polymorphisms, CAG repeat sequence (13-34 repeats in length) and p.Pro214Glu (MAF: 0.0789) located in exon 1 were identified. A missense mutation (c.47C>A/p.Pro146Glu) and in-frame deletion of a CAG sequence leading to loss of Arginine at codon 85 (c.252_254delCAG/p.Arg85-) were identified in a 70 year old patient with a Gleason Score and PSA level of 2 and 2.4ng/dL, respectively. His PSA level decreased to < 0.5 ng/dL after 9 months of androgen deprivation therapy. Identified mutations were predicted to be non-disease causing by Polyphen-2 and Mutation Taster®. Conclusion: Our data demonstrated that the frequency of germline mutations of AR was low in PCa patients in Indonesia (5.26%: 2/38 alleles), so that they are not likely to be major etiological factors. The in silico analysis of identified AR mutations in this study corroborated the clinopathology features of the patient.

Baicalein suppresses the androgen receptor (AR)-mediated prostate cancer progression via inhibiting the AR N-C dimerization and AR-coactivators interaction

BACKGROUND

Androgen receptor (AR) plays a critical role in prostate cancer (PCa) development and progression. Androgen deprivation therapy with antiandrogens to reduce androgen biosynthesis or prevent androgens from binding to AR are widely used to suppress AR-mediated PCa growth. However, most of ADT may eventually fail with development of the castration resistance after 12-24 months. Here we found that a natural product baicalein can effectively suppress the PCa progression via targeting the androgen-induced AR transactivation with little effect to AR protein expression.

METHODS

PCa cells including LNCaP, CWR22Rv1, C4-2, PC-3, and DU145, were treated with baicalein and luciferase assay was used to evaluate their effect on the AR transactivation. Cell growth and IC50 were determined by MTT assay after 48 hrs treatment. RT-PCR was used to evaluate the mRNA levels of AR target genes including PSA, TMPRSS2, and TMEPA1. Western blot was used to determine AR and PSA protein expression.

RESULTS

The natural product of baicalein can selectively inhibit AR transactivation with little effect on the other nuclear receptors, including ERα, and GR. At a low concentration, 2.5 μM of baicalein effectively suppresses the growth of AR-positive PCa cells, and has little effect on AR-negative PCa cells. Mechanism dissection suggest that baicalein can suppress AR target genes (PSA, TMPRSS2, and TMEPA1) expression in both androgen responsive LNCaP cells and castration resistant CWR22Rv1 cells, that may involve the inhibiting the AR N/C dimerization and AR-coactivators interaction.

CONCLUSIONS

Baicalein may be developed as an effective anti-AR therapy via its ability to inhibit AR transactivation and AR-mediated PCa cell growth.

Exploring the tetrahydroisoquinoline thiohydantoin scaffold blockade the androgen receptor as potent anti-prostate cancer agents

Prostate cancer (PC) is a major cause of cancer-related male death in worldwide and the identification of new and improved potent anti-PC molecules is constantly required. A novel scaffold of tetrahydroisoquinoline thiohydantoin was rationally designed based on the enzalutamide structures and our pre-work, leading to the discovery of a series of new antiproliferative compounds. Several new analogues displayed improved androgen receptor (AR) antagonistic activity, while maintaining the higher selective toxicity toward LNCaP cells (AR-rich) versus DU145 cells (AR-deficient) compared to enzalutamide. In fact, compound 55 exhibited promising in vitro antitumor activity by impairing AR unclear translocation. More importantly, 55 showed better pharmacokinetic properties compared to the compound 1 reported in our pre-work. These results demonstrate a step towards the development of novel and improved AR antagonists.

Androgen Receptor Regulation of Local Growth Hormone in Prostate Cancer Cells

Prostate cancer (PCa) growth is mainly driven by androgen receptor (AR), and tumors that initially respond to androgen deprivation therapy (ADT) or AR inhibition usually relapse into a more aggressive, castration-resistant PCa (CRPC) stage. Circulating growth hormone (GH) has a permissive role in PCa development in animal models and in human PCa xenograft growth. As GH and GH receptor (GHR) are both expressed in PCa cells, we assessed whether prostatic GH production is linked to AR activity and whether GH contributes to the castration-resistant phenotype. Using online datasets, we found that GH is highly expressed in human CRPC. We observed increased GH expression in castration-resistant C4-2 compared with castration-sensitive LNCaP cells as well as in enzalutamide (MDV3100)-resistant (MDVR) C4-2B (C4-2B MDVR) cells compared with parental C4-2B. We describe a negative regulation of locally produced GH by androgens/AR in PCa cells following treatment with AR agonists (R1881) and antagonists (enzalutamide, bicalutamide). We also show that GH enhances invasive behavior of CRPC 22Rv1 cells, as reflected by increased migration, invasion, and anchorage-independent growth, as well as expression of matrix metalloproteases. Moreover, GH induces expression of the AR splice variant 7, which correlates with antiandrogen resistance, and also induces insulinlike growth factor 1, which is implicated in PCa progression and ligand-independent AR activation. In contrast, blockade of GH action with the GHR antagonist pegvisomant reverses these effects both in vitro and in vivo. GH induction following ADT or AR inhibition may contribute to CRPC progression by bypassing androgen growth requirements.

Androgen receptor splice variants and prostate cancer: From bench to bedside

Therapeutic interventions for advanced prostate cancer (PCa) center on inhibiting androgen receptor (AR) and downstream signaling pathways. Resistance to androgen deprivation therapy and/or AR antagonists is inevitable and molecular mechanisms driving castration-resistant PCa (CR-PCa) primarily involve alterations in AR expression and activity. Detailed molecular biology work over the past decade, discussed at length in this review article, has revealed several AR transcripts that result from alternative splicing. These AR splice variants are increased in cell and mouse models of CR-PCa and in CR-PCa tumors. Several AR variants lack the ligand binding domain, but retain their ability to bind DNA and activate transcription-linking constitutive AR function and therapeutic failure. ARV7 is the only variant endogenously detected at the protein level and thus has undergone more thorough molecular characterization. Clinical trials in PCa are currently investigating ARV7 utility as a biomarker and new therapeutics that inhibit ARV7 . Overall, this review will illustrate the historical perspectives of AR splice variant discovery using fundamental molecular biology techniques and how it changed the clinical approach to both therapeutic decisions and strategy. The body of work investigating AR splice variants in PCa represents a true example of translational research from bench to bedside.

Current Insights into Long Non-Coding RNAs (LncRNAs) in Prostate Cancer

The importance of long non-coding RNAs (lncRNAs) in the pathogenesis of various malignancies has been uncovered over the last few years. Their dysregulation often contributes to or is a result of tumour progression. In prostate cancer, the most common malignancy in men, lncRNAs can promote castration resistance, cell proliferation, invasion, and metastatic spread. Expression patterns of lncRNAs often change during tumour progression; their expression levels may constantly rise (e.g., HOX transcript antisense RNA, HOTAIR), or steadily decrease (e.g., downregulated RNA in cancer, DRAIC). In prostate cancer, lncRNAs likewise have diagnostic (e.g., prostate cancer antigen 3, PCA3), prognostic (e.g., second chromosome locus associated with prostate-1, SChLAP1), and predictive (e.g., metastasis-associated lung adenocarcinoma transcript-1, MALAT-1) functions. Considering their dynamic role in prostate cancer, lncRNAs may also serve as therapeutic targets, helping to prevent development of castration resistance, maintain stable disease, and prohibit metastatic spread.

Food components and contaminants as (anti)androgenic molecules

Androgens, the main male sex steroids, are the critical factors responsible for the development of the male phenotype during embryogenesis and for the achievement of sexual maturation and puberty. In adulthood, androgens remain essential for the maintenance of male reproductive function and behavior. Androgens, acting through the androgen receptor (AR), regulate male sexual differentiation during development, sperm production beginning from puberty, and maintenance of prostate homeostasis. Several substances present in the environment, now classified as endocrine disruptors (EDCs), strongly interfere with androgen actions in reproductive and non-reproductive tissues. EDCs are a heterogeneous group of xenobiotics which include synthetic chemicals used as industrial solvents/lubricants, plasticizers, additives, agrochemicals, pharmaceutical agents, and polyphenols of plant origin. These compounds are even present in the food as components (polyphenols) or food/water contaminants (pesticides, plasticizers used as food packaging) rendering the diet as the main route of exposure to EDCs for humans. Although huge amount of literature reports the (anti)estrogenic effects of different EDCs, relatively scarce information is available on the (anti)androgenic effects of EDCs. Here, the effects and mechanism of action of phytochemicals and pesticides and plasticizers as possible modulators of AR activities will be reviewed taking into account that insight derived from principles of endocrinology are required to estimate EDC consequences on endocrine deregulation and disease.

Phytotherapeutic approach: a new hope for polycyclic aromatic hydrocarbons induced cellular disorders, autophagic and apoptotic cell death

Polycyclic aromatic hydrocarbons (PAHs) comprise the major class of cancer-causing chemicals and are ranked ninth among the chemical compounds threatening to humans. Moreover, interest in PAHs has been mainly due to their genotoxic, teratogenic, mutagenic and carcinogenic property. Polymorphism in cytochrome P450 (CYP450) and aryl hydrocarbon receptor (AhR) has the capacity to convert procarcinogens into carcinogens, which is an imperative factor contributing to individual susceptibility to cancer development. The carcinogenicity potential of PAHs is related to their ability to bind to DNA, thereby enhances DNA cross-linking, causing a series of disruptive effects which can result in tumor initiation. They induce cellular toxicity by regulating the generation of reactive oxygen species (ROS), which arbitrate apoptosis. Additionally, cellular toxicity-mediated apoptotic and autophagic cell death and immune suppression by industrial pollutants PAH, provide fertile ground for the proliferation of mutated cells, which results in cancer growth and progression. PAHs play a foremost role in angiogenesis necessary for tumor metastasization by promoting the upregulation of metalloproteinase-9 (MMP-9), vascular endothelial growth factor (VEGF) and hypoxia inducible factor (HIF) in human cancer cells. This review sheds light on the molecular mechanisms of PAHs induced cancer development as well as autophagic and apoptotic cell death. Besides that authors have unraveled how phytotherapeutics is an alternate potential therapeutics acting as a savior from the toxic effects of PAHs for safer and cost effective perspectives.

Androgen receptor-dependent and -independent mechanisms driving prostate cancer progression: Opportunities for therapeutic targeting from multiple angles

Despite aggressive treatment for localized cancer, prostate cancer (PC) remains a leading cause of cancer-related death for American men due to a subset of patients progressing to lethal and incurable metastatic castrate-resistant prostate cancer (CRPC). Organ-confined PC is treated by surgery or radiation with or without androgen deprivation therapy (ADT), while options for locally advanced and disseminated PC include radiation combined with ADT, or systemic treatments including chemotherapy. Progression to CRPC results from failure of ADT, which targets the androgen receptor (AR) signaling axis and inhibits AR-driven proliferation and survival pathways. The exact mechanisms underlying the transition from androgen-dependent PC to CRPC remain incompletely understood. Reactivation of AR has been shown to occur in CRPC despite depletion of circulating androgens by ADT. At the same time, the presence of AR-negative cell populations in CRPC has also been identified. While AR signaling has been proposed as the primary driver of CRPC, AR-independent signaling pathways may represent additional mechanisms underlying CRPC progression. Identification of new therapeutic strategies to target both AR-positive and AR-negative PC cell populations and, thereby, AR-driven as well as non-AR-driven PC cell growth and survival mechanisms would provide a two-pronged approach to eliminate CRPC cells with potential for synthetic lethality. In this review, we provide an overview of AR-dependent and AR-independent molecular mechanisms which drive CRPC, with special emphasis on the role of the Jak2-Stat5a/b signaling pathway in promoting castrate-resistant growth of PC through both AR-dependent and AR-independent mechanisms.

Transcriptional regulation of core autophagy and lysosomal genes by the androgen receptor promotes prostate cancer progression

AR (androgen receptor) signaling is crucial for the development and maintenance of the prostate as well as the initiation and progression of prostate cancer. Despite the AR's central role in prostate cancer progression, it is still unclear which AR-mediated processes drive the disease. Here, we identified 4 core autophagy genes: ATG4B, ATG4D, ULK1, and ULK2, in addition to the transcription factor TFEB, a master regulator of lysosomal biogenesis and function, as transcriptional targets of AR in prostate cancer. These findings were significant in light of our recent observation that androgens promoted prostate cancer cell growth in part through the induction of autophagy. Expression of these 5 genes was essential for maximal androgen-mediated autophagy and cell proliferation. In addition, expression of each of these 5 genes alone or in combination was sufficient to increase prostate cancer cell growth independent of AR activity. Further, bioinformatic analysis demonstrated that the expression of these genes correlated with disease progression in 3 separate clinical cohorts. Collectively, these findings demonstrate a functional role for increased autophagy in prostate cancer progression, provide a mechanism for how autophagy is augmented, and highlight the potential of targeting this process for the treatment of advanced prostate cancer.

Ailanthone targets p23 to overcome MDV3100 resistance in castration-resistant prostate cancer

Androgen receptor (AR) antagonist MDV3100 is the first therapeutic approach in treating castration-resistant prostate cancer (CRPC), but tumours frequently become drug resistant via multiple mechanisms including AR amplification and mutation. Here we identify the small molecule Ailanthone (AIL) as a potent inhibitor of both full-length AR (AR-FL) and constitutively active truncated AR splice variants (AR-Vs). AIL binds to the co-chaperone protein p23 and prevents AR's interaction with HSP90, thus resulting in the disruption of the AR-chaperone complex followed by ubiquitin/proteasome-mediated degradation of AR as well as other p23 clients including AKT and Cdk4, and downregulates AR and its target genes in PCa cell lines and orthotopic animal tumours. In addition, AIL blocks tumour growth and metastasis of CRPC. Finally, AIL possesses favourable drug-like properties such as good bioavailability, high solubility, lack of CYP inhibition and low hepatotoxicity. In general, AIL is a potential candidate for the treatment of CRPC.

Prostate cancers often become castration resistant due to alternative expression of androgen receptor (AR) splice variants. Here, the authors screened a library of natural compounds and identified Ailanthone as a potent inhibitor of AR through its binding to the co-chaperone protein p23 that, by preventing AR interaction with HSP90, results in ubiquitin/proteasome-mediated degradation of the receptor.

Targeting the N-Terminal Domain of the Androgen Receptor: A New Approach for the Treatment of Advanced Prostate Cancer

: Despite the recent approval and widespread use of abiraterone acetate and enzalutamide for the treatment of castration-resistant prostate cancer (CRPC), this disease still poses significant management challenges because of various tumor escape mechanisms, including those that allow androgen receptor (AR) signaling to remain active. These AR-related resistance mechanisms include AR gene amplification or overexpression, constitutively active ligand-independent AR splice variants, and gain-of-function mutations involving the AR ligand-binding domain (LBD), among others. Therefore, the development of AR-targeted therapies that function independently of the LBD represents an unmet medical need and has the potential to overcome many of these resistance mechanisms. This article discusses N-terminal domain (NTD) inhibition as a novel concept in the field of AR-directed therapies for prostate cancer. AR NTD-targeting agents have the potential to overcome shortcomings of current hormonal therapies by inhibiting all forms of AR-mediated transcriptional activity, and as a result, may affect a broader AR population including mutational and splice variant ARs. Indeed, the first clinical trial of an AR NTD inhibitor is now underway.

IMPLICATIONS FOR PRACTICE

Because of emerging resistance mechanisms that involve the ligand-binding domain of the androgen receptor (AR), there is currently no effective treatment addressing tumor escape mechanisms related to current AR-targeted therapies. Many patients still demonstrate limited clinical response to current hormonal agents, and castration-resistant prostate cancer remains a lethal disease. Intense research efforts are under way to develop therapies to target resistance mechanisms, including those directed at other parts of the AR molecule. A novel small-molecule agent, EPI-506, represents a new pharmaceutical class, AR N-terminal domain inhibitors, and shows preclinical promise to overcome many known resistance mechanisms related to novel hormonal therapies.

Molecular mechanisms underlying resistance to androgen deprivation therapy in prostate cancer

Prostate cancer (PCa) is the most widely diagnosed male cancer in the Western World and while low- and intermediate-risk PCa patients have a variety of treatment options, metastatic patients are limited to androgen deprivation therapy (ADT). This treatment paradigm has been in place for 75 years due to the unique role of androgens in promoting growth of prostatic epithelial cells via the transcription factor androgen receptor (AR) and downstream signaling pathways. Within 2 to 3 years of ADT, disease recurs-at which time, patients are considered to have castration-recurrent PCa (CR-PCa). A universal mechanism by which PCa becomes resistant to ADT has yet to be discovered. In this review article, we discuss underlying molecular mechanisms by which PCa evades ADT. Several major resistance pathways center on androgen signaling, including intratumoral and adrenal androgen production, AR-overexpression and amplification, expression of AR mutants, and constitutively-active AR splice variants. Other ADT resistance mechanisms, including activation of glucocorticoid receptor and impairment of DNA repair pathways are also discussed. New therapies have been approved for treatment of CR-PCa, but increase median survival by only 2-8 months. We discuss possible mechanisms of resistance to these new ADT agents. Finally, the practicality of the application of "precision oncology" to this continuing challenge of therapy resistance in metastatic or CR-PCa is examined. Empirical validation and clinical-based evidence are definitely needed to prove the superiority of "precision" treatment in providing a more targeted approach and curative therapies over the existing practices that are based on biological "cause-and-effect" relationship.