Prostate specific antigen gene regulation by androgen receptor

Preanalytical stability of molecular forms of prostate-specific antigen in serum samples (PSA, free PSA, [-2]proPSA) and their impact on fPSA/tPSA ratio and PHI

BACKGROUND

Prostate cancer is a common cancer in men. Detection methods include the measurement of biomarkers: prostate-specific antigen (PSA), free PSA, [-2]proPSA, and the calculated indices: fPSA/tPSA ratio and Prostate Health Index (PHI). Proper preanalytical conditions are crucial for precise measurement and failure to adhere to protocols or regulations can influence the diagnostic algorithm. We assessed the stability of the above-mentioned biomarkers, fPSA/tPSA ratio and PHI, under various pre-analytical conditions.

METHODS

Serum samples from 45 males were collected and stored under specific conditions before tPSA, fPSA, and [-2]proPSA were measured. Subsequently, the fPSA/tPSA and PHI were calculated.

RESULTS

tPSA, fPSA, and [-2]proPSA remained stable during the two freeze-thaw cycles. Storage at 4°C and 22°C resulted in stable tPSA concentrations. However, fPSA levels decreased and [-2]proPSA levels increased over time. The fPSA/tPSA ratio remained stable for 72 h, at which point a decrease was observed in the samples kept at 4°C and 22°C. A gradual increase in PHI was observed in the samples kept at 4°C and 22°C.

CONCLUSIONS

All biomarkers remained stable during two freeze-thaw cycles. tPSA was the most stable analyte when stored at 4°C, as well as at RT. A gradual increase of [-2]proPSA and a slight decrease in fPSA were observed during the storage test. This led to a decrease in the fPSA/tPSA ratio and an elevation in the PHI. We therefore recommend measuring prostate biomarkers promptly following blood collection.

IMPACT

Understanding the pre-analytical stability of prostate biomarkers helps prevent false positive results and improve the accuracy of diagnostics for prostate cancer.

Androgen drives melanoma invasiveness and metastatic spread by inducing tumorigenic fucosylation

Melanoma incidence and mortality rates are historically higher for men than women. Although emerging studies have highlighted tumorigenic roles for the male sex hormone androgen and its receptor (AR) in melanoma, cellular and molecular mechanisms underlying these sex-associated discrepancies are poorly defined. Here, we delineate a previously undisclosed mechanism by which androgen-activated AR transcriptionally upregulates fucosyltransferase 4 (FUT4) expression, which drives melanoma invasiveness by interfering with adherens junctions (AJs). Global phosphoproteomic and fucoproteomic profiling, coupled with in vitro and in vivo functional validation, further reveal that AR-induced FUT4 fucosylates L1 cell adhesion molecule (L1CAM), which is required for FUT4-increased metastatic capacity. Tumor microarray and gene expression analyses demonstrate that AR-FUT4-L1CAM-AJs signaling correlates with pathological staging in melanoma patients. By delineating key androgen-triggered signaling that enhances metastatic aggressiveness, our findings help explain sex-associated clinical outcome disparities and highlight AR/FUT4 and its effectors as potential prognostic biomarkers and therapeutic targets in melanoma.

Evaluation of AR, AR-V7, and p160 family as biomarkers for prostate cancer: insights into the clinical significance and disease progression

PURPOSE

To assess the role of the p160 family, AR, and AR-V7 in different initial presentations of prostate cancer and their association with clinical endpoints related to tumor progression.

METHODS

The study sample comprises 155 patients who underwent radical prostatectomy and 11 healthy peripheral zone biopsies as the control group. Gene expression was quantified by qPCR from the tissue specimens. The statistical analysis investigated correlations between gene expression levels, associations with disease presence, and clinicopathological features. Additionally, ROC curves were applied for distinct PCa presentations, and time-to-event analysis was used for clinical endpoints.

RESULTS

The AR-V7 diagnostic performance for any PCa yielded an AUC of 0.77 (p < 0.05). For locally advanced PCa, the AR-V7 AUC was 0.65 (p < 0.05). Moreover, the metastasis group had a higher expression of SRC-1 than the non-metastatic group (p < 0.05), showing a shorter time to metastasis in the over-expressed group (p = 0.005). Patients with disease recurrence had super-expression of AR levels (p < 0.0005), with a shorter time-to-recurrence in the super-expression group (p < 0.0001).

CONCLUSION

Upregulation of SRC-1 indicates a higher risk of progression to metastatic disease in a shorter period, which warrants further research to be applied as a clinical tool. Additionally, AR may be used as a predictor for PCa recurrence. Furthermore, AR-V7 may be helpful as a diagnostic tool for PCa and locally advanced cancer, comparable with other investigated tools.

Genome-wide association study of prostate-specific antigen levels in 392,522 men identifies new loci and improves cross-ancestry prediction

We conducted a multi-ancestry genome-wide association study of prostate-specific antigen (PSA) levels in 296,754 men (211,342 European ancestry; 58,236 African ancestry; 23,546 Hispanic/Latino; 3,630 Asian ancestry; 96.5% of participants were from the Million Veteran Program). We identified 318 independent genome-wide significant (p≤5e-8) variants, 184 of which were novel. Most demonstrated evidence of replication in an independent cohort (n=95,768). Meta-analyzing discovery and replication (n=392,522) identified 447 variants, of which a further 111 were novel. Out-of-sample variance in PSA explained by our new polygenic risk score reached 16.9% (95% CI=16.1%-17.8%) in European ancestry, 9.5% (95% CI=7.0%-12.2%) in African ancestry, 18.6% (95% CI=15.8%-21.4%) in Hispanic/Latino, and 15.3% (95% CI=12.7%-18.1%) in Asian ancestry, and lower for higher age. Our study highlights how including proportionally more participants from underrepresented populations improves genetic prediction of PSA levels, with potential to personalize prostate cancer screening.

Pinostilbene inhibits full-length and splice variant of androgen receptor in prostate cancer

Prostate cancer is the most prevalent cancer in men worldwide and is promoted by the sex hormone androgen. Expression of androgen from the testis can be significantly reduced through castration. However, as most prostate cancer patients acquire castration resistance, additional therapeutic solutions are necessary. Although anti-androgens, such as enzalutamide, have been used to treat castration-resistant prostate cancer (CRPC), enzalutamide-resistant CRPC (Enz-resistant CRPC) has emerged. Therefore, development of novel treatments for Enz-resistant CRPC is urgent. In this study, we found a novel anti-androgen called pinostilbene through screening with a GAL4-transactivation assay. We confirmed that pinostilbene directly binds to androgen receptor (AR) and inhibits its activation and translocalization. Pinostilbene treatment also reduced the protein level and downstream gene expression of AR. Furthermore, pinostilbene reduced the protein level of AR variant 7 in the Enz-resistant prostate cancer cell line 22Rv1 and inhibited cell viability and proliferation. Our results suggest that pinostilbene has the potential to treat Enz-resistant CRPC.

Molecular Insight into Prostate Cancer: Preventive Role of Selective Bioactive Molecules

Prostate cancer (CaP) is one of the most prevalent male malignancies, accounting for a considerable number of annual mortalities. However, the prompt identification of early-stage CaP often faces delays due to diverse factors, including socioeconomic inequalities. The androgen receptor (AR), in conjunction with various other signaling pathways, exerts a central influence on the genesis, progression, and metastasis of CaP, with androgen deprivation therapy (ADT) serving as the primary therapeutic strategy. Therapeutic modalities encompassing surgery, chemotherapy, hormonal intervention, and radiotherapy have been formulated for addressing early and metastatic CaP. Nonetheless, the heterogeneous tumor microenvironment frequently triggers the activation of signaling pathways, culminating in the emergence of chemoresistance, an aspect to which cancer stem cells (CSCs) notably contribute. Phytochemicals emerge as reservoirs of bioactive agents conferring manifold advantages against human morbidity. Several of these phytochemicals demonstrate potential chemoprotective and chemosensitizing properties against CaP, with selectivity exhibited towards malignant cells while sparing their normal counterparts. In this context, the present review aims to elucidate the intricate molecular underpinnings associated with metastatic CaP development and the acquisition of chemoresistance. Moreover, the contributions of phytochemicals to ameliorating CaP initiation, progression, and chemoresistance are also discussed.

Trapa bispinosa Roxb. Pericarp Extract Exerts 5α-Reductase Inhibitory Activity in Castrated Benign Prostatic Hyperplasia Model Mice

Trapa bispinosa Roxb. pericarp extract (TBE) has a polyphenol-rich composition and exhibits potent antioxidant and anti-glycation activities in vitro. In the present study, we investigated the inhibitory effects of TBE on 5α-reductase in vitro using LNCaP cells and in vivo using a mouse model of castrated benign prostatic hyperplasia. TBE showed concentration-dependent inhibitory effects in the 5α-reductase (5αR) activity assay. In a reporter assay using AR-Luc/LNCaP cells, TBE inhibited the activity induced by testosterone, but not that induced by dihydrotestosterone. TBE also suppressed prostate cell proliferation, prostate-specific antigens, and transmembrane protease serine 2 expression in a castrated benign prostatic hyperplasia mouse model. In addition, ellagic acid, but not gallic acid, decreased 5αR and AR-Luc activities. Together, these results suggest a potential role for TBE in benign prostatic hyperplasia through inhibition of 5αR.

Microfluidic-based prostate cancer model for investigating the secretion of prostate-specific antigen and microRNAs in vitro

The study of prostate cancer in vitro relies on established cell lines that lack important physiological characteristics, such as proper polarization and expression of relevant biomarkers. Microphysiological systems (MPS) can replicate cancer microenvironments and lead to cellular phenotypic changes that better represent organ physiology in vitro. In this study, we developed an MPS model comprising conventional prostate cancer cells to evaluate their activity under dynamic culture conditions. Androgen-sensitive (LNCaP) and androgen-insensitive (PC3) cells were grown in conventional and 3D cultures, both static and dynamic. Cell morphology, the secretion of prostate-specific antigen, and the expression of key prostate markers and microRNAs were analyzed. LNCaP formed spheroids in 3D and MPS cultures, with morphological changes supported by the upregulation of cytokeratins and adhesion proteins. LNCaP also maintained a constant prostate-specific antigen secretion in MPS. PC3 cells did not develop complex structures in 3D and MPS cultures. PSA expression at the gene level was downregulated in LNCaP-MPS and considerably upregulated in PC3-MPS. MicroRNA expression was altered by the 3D static and dynamic culture, both intra- and extracellularly. MicroRNAs associated with prostate cancer progression were mostly upregulated in LNCaP-MPS. Overall dynamic cell culture substantially altered the morphology and expression of LNCaP cells, arguably augmenting their prostate cancer phenotype. This novel approach demonstrates that microRNA expression in prostate cancer cells is sensitive to external stimuli and that MPS can effectively promote important physiological changes in conventional prostate cancer models.

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.

Delayed puberty, gonadotropin abnormalities and subfertility in male Padi2/Padi4 double knockout mice

BACKGROUND

Peptidylarginine deiminase enzymes (PADs) convert arginine residues to citrulline in a process called citrullination or deimination. Recently, two PADs, PAD2 and PAD4, have been linked to hormone signaling in vitro and the goal of this study was to test for links between PAD2/PAD4 and hormone signaling in vivo.

METHODS

Preliminary analysis of Padi2 and Padi4 single knockout (SKO) mice did not find any overt reproductive defects and we predicted that this was likely due to genetic compensation. To test this hypothesis, we created a Padi2/Padi4 double knockout (DKO) mouse model and tested these mice along with wild-type FVB/NJ (WT) and both strains of SKO mice for a range of reproductive defects.

RESULTS

Controlled breeding trials found that male DKO mice appeared to take longer to have their first litter than WT controls. This tendency was maintained when these mice were mated to either DKO or WT females. Additionally, unsexed 2-day old DKO pups and male DKO weanlings both weighed significantly less than their WT counterparts, took significantly longer than WT males to reach puberty, and had consistently lower serum testosterone levels. Furthermore, 90-day old adult DKO males had smaller testes than WT males with increased rates of germ cell apoptosis.

CONCLUSIONS

The Padi2/Padi4 DKO mouse model provides a new tool for investigating PAD function and outcomes from our studies provide the first in vivo evidence linking PADs with hormone signaling.

Inhibitory effects of Centella asiatica (L.) Urban on enlarged prostate through androgen receptor and PI3K/Akt signaling pathways

Centella asiatica (L.) Urban (C. asiatica) is a traditional herbal medicine that has been used for wound healing and anti-inflammation since ancient times. Various biological effects of C. asiatica ethanolic extract (CAE) were previously reported. However, in our previous study, C. asiatica aqueous extract (CAA) exhibited higher inhibitory activity on benign prostatic hyperplasia (BPH) than CAE. Therefore, the aim of this study was to investigate the effect of CAA on BPH, and elucidate the inhibitory mechanism through in vitro and in vivo experiments as well as metabolite analysis of CAA. A BPH rat model was induced by daily subcutaneous injection of testosterone propionate (TP, 3 mg kg^-1) dissolved in corn oil for 4 weeks after castration. The experimental group, the CAA treatment group, was orally administered CAA (100 mg kg^-1) for 4 weeks while inducing prostatic hyperplasia. Saw palmetto extract (Saw, 100 mg kg^-1) and Finasteride (Fi, 1 mg kg^-1) were used as positive controls and were administered orally for 4 weeks. CAA significantly inhibited androgen receptor signaling related factors overexpressed by dihydrotestosterone (DHT) treatment in prostate cell lines. Afterwards, the testosterone-induced BPH model was used to verify the alleviation efficacy of CAA in prostatic hyperplasia. Prostate size and the thickness of the prostate tissue epithelium were significantly decreased in the group treated with CAA compared to those in the BPH group. The results of protein expression in the prostate tissue confirmed that CAA inhibited androgen receptor signaling in BPH and decreased the expression of growth factors. Moreover, CAA suppressed the expression of the PI3K/Akt pathway and cell proliferation-related factors compared to the BPH group. Taken together, these results indicate that CAA improves the inhibitory efficacy of BPH by inhibiting the androgen receptor and PI3K/Akt pathways, suggesting that CAA may be a promising candidate for biopharmaceutical formulations of BPH.

Testosterone does not affect lower urinary tract symptoms while improving markers of prostatitis in men with benign prostatic hyperplasia: a randomized clinical trial

PURPOSE

Benign Prostatic Hyperplasia (BPH) is a result of prostate inflammation, frequently occurring in metabolic syndrome (MetS). Low testosterone is common in MetS. A randomized clinical trial was designed to evaluate if 24 weeks of testosterone therapy (TTh) in BPH men with MetS and low testosterone improve urinary symptoms and prostate inflammation.

METHODS

One-hundred-twenty men with MetS waitlisted for BPH surgery were enrolled. They were categorized into normal testosterone (TT ≥ 12 nmol/L and cFT ≥ 225 pmol/L; n = 48) and testosterone deficient (TD) (TT < 12 nmol/L and/or cFT < 225 pmol/L; n = 72) then randomized to testosterone gel 2% (5 g/daily) or placebo for 24 weeks. At baseline and follow-up, questionnaires for urinary symptoms and trans-rectal ultrasound were performed. Prostate tissue was collected for molecular and histopathological analyses.

RESULTS

No differences in the improvement of urinary symptoms were found between TTh and placebo (OR [95% CI] 0.96 [0.39; 2.37]). In TD + TTh, increase in prostate but not adenoma volume was observed (2.64 mL [0.07; 5.20] and 1.82 mL [- 0.46; 0.41], respectively). Ultrasound markers of inflammation were improved. In a subset of 61 men, a hyper-expression of several pro-inflammatory genes was found in TD + placebo when compared with normal testosterone. TTh was able to counteract this effect. For 80 men, the inflammatory infiltrate was higher in TD + placebo than in normal testosterone (0.8 points [0.2; 1.4]) and TD + TTh men (0.9 points [0.2; 1.5]).

CONCLUSIONS

Twenty-four weeks of TTh in TD men with BPH and MetS improves ultrasound, molecular and histological proxies of prostate inflammation. This does not result in symptom improvement.

Baseline Plasma Tumor DNA (ctDNA) Correlates with PSA Kinetics in Metastatic Castration-Resistant Prostate Cancer (mCRPC) Treated with Abiraterone or Enzalutamide

Background: Baseline high circulating tumor DNA (ctDNA) fraction in plasma and androgen receptor (AR) copy number (CN) gain identify mCRPC patients with worse outcomes. This study aimed to assess if ctDNA associates with PSA kinetics. Methods: In this prospective biomarker study, we evaluate ctDNA fraction and AR CN from plasma samples. We divided patients into high and low ctDNA level and in AR gain and AR normal. Results: 220 baseline samples were collected from mCRPC treated with abiraterone (n = 140) or enzalutamide (n = 80). A lower rate of PSA decline ≥ 50% was observed in patients with high ctDNA (p = 0.017) and AR gain (p = 0.0003). Combining ctDNA fraction and AR CN, we found a different median PSA progression-free survival (PFS) among four groups: (1) low ctDNA/AR normal, (2) high ctDNA/AR normal, (3) low ctDNA/AR gain, and (4) high ctDNA/AR gain (11.4 vs. 5.0 vs. 4.8 vs. 3.7 months, p < 0.0001). In a multivariable analysis, high ctDNA, AR gain, PSA DT, PSA DT velocity remained independent predictors of PSA PFS. Conclusions: Elevated ctDNA levels and AR gain are negatively and independently correlated with PSA kinetics in mCRPC men treated with abiraterone or enzalutamide.

Antiandrogenic activity of Riboflavin 5'-phosphate (FMN) in 22Rv1 and LNCaP human prostate cancer cell lines

The androgen receptor is a hormone activated transcription factor that regulates the development and maintenance of male characteristics and represents one of the most well-established drug targets, being implicated not only in prostate cancer but also in many non-cancerous human diseases including androgenetic alopecia, acne vulgaris, and hirsutism. In this study, the antiandrogenic effects of FMN were investigated in 22Rv1 and LNCaP prostate cancer cells. FMN inhibited dihydrotestosterone (DHT)-induced protein expression of androgen receptor in 22Rv1cells. In another prostate cancer LNCaP cells, FMN decreased the protein level of DHT-induced prostate specific antigen (PSA). In addition, FMN downregulated DHT-induced mRNA expression of androgen regulated genes in both cell lines, showing less prominent inhibition in 22Rv1cells where androgen receptor had been significantly decreased by FMN. FMN was found to bind androgen receptor, demonstrating that it acted as a competitive androgen receptor antagonist. FMN increased the phosphorylation of Akt in 22Rv1 cells and this increment was abrogated by PI3K inhibitor wortmannin, resulting in a rescued androgen receptor protein level which was decreased by FMN. Additionally, FMN was found to increase the mRNA and protein level of E3 ligase mouse double minute 2. Our data suggest that the androgen receptor signaling is regulated through PI3K-Akt-MDM2 pathway in 22Rv1 cells. Together, our results indicate that FMN facilitated the degradation of androgen receptor in 22Rv1 cells and inhibited the expression of androgen regulated genes by competing the binding of DHT to androgen receptor in LNCaP cells, demonstrating its therapeutic potential as an antiandrogen.

Strategies for Isolating and Propagating Circulating Tumor Cells in Men with Metastatic Prostate Cancer

Selecting a well-suited method for isolating/characterizing circulating tumor cells (CTCs) is challenging. Evaluating sensitive and specific markers for prostate cancer (PCa)-specific CTC identification and analysis is crucial. We used the CellCollector EpCAM-functionalized system (CC-EpCAM) and evaluated and developed a PCa-functionalized version (CC-PCa); we then compared CTC isolation techniques that exploit the physical and biological properties of CTCs. We established two cohorts of metastatic PCa patients (mPCa; 15 in cohort 1 and 10 in cohort 2). CTC cultivation experiments were conducted with two capturing methods (Ficoll and ScreenCell). The most sensitive detection rates and highest CTC counts were reached with the CC-PCa and ScreenCell system. Patients with ≥5 CTCs isolated with CC-EpCAM had an overall survival (OS) of 0.93 years, and patients with ≥5 CTCs isolated with CC-PCa had an OS of 1.5 years in cohort 1. Nevertheless, we observed the highest sensitivity and specificity for 24-month survival by the Ficoll with CD45 depletion and ScreenCell system with May-Grunwald Giemsa (MGG) staining. The EpCAM molecule is an essential factor related to OS for CTC isolation based on biological properties in mPCa patients. The best-suited CTC capture system is not limited to one characteristic of cells but adapted to downstream analysis.

Assessment of factors associated with PSA level in prostate cancer cases and controls from three geographical regions

It is being debated whether prostate-specific antigen (PSA)-based screening effectively reduces prostate cancer mortality. Some of the uncertainty could be related to deficiencies in the age-based PSA cut-off thresholds used in screening. Current study considered 2779 men with prostate cancer and 1606 men without a cancer diagnosis, recruited for various studies in New Zealand, US, and Taiwan. Association of PSA with demographic, lifestyle, clinical characteristics (for cases), and the aldo–keto reductase 1C3 (AKR1C3) rs12529 genetic polymorphisms were analysed using multiple linear regression and univariate modelling. Pooled multivariable analysis of cases showed that PSA was significantly associated with demographic, lifestyle, and clinical data with an interaction between ethnicity and age further modifying the association. Pooled multivariable analysis of controls data also showed that demographic and lifestyle are significantly associated with PSA level. Independent case and control analyses indicated that factors associated with PSA were specific for each cohort. Univariate analyses showed a significant age and PSA correlation among all cases and controls except for the US-European cases while genetic stratification in cases showed variability of correlation. Data suggests that unique PSA cut-off thresholds factorized with demographics, lifestyle and genetics may be more appropriate for prostate cancer screening.

Lysine Acetyltransferases and Their Role in AR Signaling and Prostate Cancer

The development and growth of a normal prostate gland, as well as its physiological functions, are regulated by the actions of androgens through androgen receptor (AR) signaling which drives multiple cellular processes including transcription, cellular proliferation, and apoptosis in prostate cells. Post-translational regulation of AR plays a vital role in directing its cellular activities via modulating its stability, nuclear localization, and transcriptional activity. Among various post-translational modifications (PTMs), acetylation is an essential PTM recognized in AR and is governed by the regulated actions of acetyltransferases and deacetyltransferases. Acetylation of AR has been identified as a critical step for its activation and depending on the site of acetylation, the intracellular dynamics and activity of the AR can be modulated. Various acetyltransferases such as CBP, p300, PCAF, TIP60, and ARD1 that are known to acetylate AR, may directly coactivate the AR transcriptional function or help to recruit additional coactivators to functionally regulate the transcriptional activity of the AR. Aberrant expression of acetyltransferases and their deregulated activities have been found to interfere with AR signaling and play a key role in development and progression of prostatic diseases, including prostate cancer (PCa). In this review, we summarized recent research advances aimed at understanding the role of various lysine acetyltransferases (KATs) in the regulation of AR activity at the level of post-translational modifications in normal prostate physiology, as well as in development and progression of PCa. Considering the critical importance of KATs in modulating AR activity in physiological and patho-physiological context, we further discussed the potential of targeting these enzymes as a therapeutic option to treat AR-related pathology in combination with hormonal therapy.

Melatonin and Prostate Cancer: Anti-tumor Roles and Therapeutic Application

Melatonin is an endogenous indoleamine that has been shown to inhibit tumor growth in laboratory models of prostate cancer. Prostate cancer risk has additionally been associated with exogenous factors that interfere with normal pineal secretory activity, including aging, poor sleep, and artificial light at night. Therefore, we aim to expand on the important epidemiological evidence, and to review how melatonin can impede prostate cancer. More specifically, we describe the currently known mechanisms of melatonin-mediated oncostasis in prostate cancer, including those that relate to the indolamine's ability to modulate metabolic activity, cell cycle progression and proliferation, androgen signaling, angiogenesis, metastasis, immunity and oxidative cell status, apoptosis, genomic stability, neuroendocrine differentiation, and the circadian rhythm. The outlined evidence underscores the need for clinical trials to determine the efficacy of supplemental, adjunct, and adjuvant melatonin therapy for the prevention and treatment of prostate cancer.

Insights of RKIP-Derived Suppression of Prostate Cancer

Simple Summary

Despite an intensive research effort in the past few decades, prostate cancer (PC) remains a top cause of cancer death in men, particularly in the developed world. The major cause of fatality is the progression of local prostate cancer to metastasis disease. Treatment of patients with metastatic prostate cancer (mPC) is generally ineffective. Based on the discovery of mPC relying on androgen for growth, many patients with mPC show an initial response to the standard of care: androgen deprivation therapy (ADT). However, lethal castration resistant prostate cancers (CRPCs) commonly develop. It is widely accepted that intervention of metastatic progression of PC is a critical point of intervention to reduce PC death. Accumulative evidence reveals a role of RKIP in suppression of PC progression towards mPC. We will review current evidence and discuss the potential utilization of RKIP in preventing mPC progression.

Abstract

Prostate cancer (PC) is a major cause of cancer death in men. The disease has a great disparity in prognosis. Although low grade PCs with Gleason scores ≤ 6 are indolent, high-risk PCs are likely to relapse and metastasize. The standard of care for metastatic PC (mPC) remains androgen deprivation therapy (ADT). Resistance commonly occurs in the form of castration resistant PC (CRPC). Despite decades of research efforts, CRPC remains lethal. Understanding of mechanisms underpinning metastatic progression represents the overarching challenge in PC research. This progression is regulated by complex mechanisms, including those regulating PC cell proliferation, epithelial–mesenchymal transition (EMT), and androgen receptor (AR) signaling. Among this PC metastatic network lies an intriguing suppressor of PC metastasis: the Raf kinase inhibitory protein (RKIP). Clinically, the RKIP protein is downregulated in PC, and showed further reduction in mPC. In xenograft mouse models for PC, RKIP inhibits metastasis. In vitro, RKIP reduces PC cell invasion and sensitizes PC cells to therapeutic treatments. Mechanistically, RKIP suppresses Raf-MEK-ERK activation and EMT, and modulates extracellular matrix. In return, Snail, NFκB, and the polycomb protein EZH2 contribute to inhibition of RKIP expression. In this review, we will thoroughly analyze RKIP’s tumor suppression actions in PC.

Gut Microbiota Composition across Normal Range Prostate-Specific Antigen Levels

Animal studies have shown the interaction between androgens and the gut microbiome directly and indirectly; however, limited evidence from human studies is available. To evaluate the association between prostate-specific antigen (PSA) levels within the normal range, reflective of androgen receptor activity, and the gut microbiota composition, a cross-sectional analysis was performed in 759 Korean men aged between 25 and 78 years with normal PSA levels of ≤4.0 ng/mL. We evaluated the biodiversity of gut microbiota as well as the taxonomic and functional signatures associated with PSA levels using 16S rRNA gene sequencing data. PSA levels within the normal range were categorized into three groups: lowest quartile (G1), interquartile range (G2, reference), and highest quartile (G3). The G3 group had higher microbial richness than the G2 group, although it was dominated by a few bacteria. An increase in Escherichia/Shigella abundance and a reduction in Megamonas abundance in the G3 group were also detected. A U-shaped relationship was observed between the three groups across most analyses, including biodiversity, taxonomic composition, and inferred pathways in the gut microbiota. This study showed different microbiota patterns across PSA levels within the normal range. Further studies are required to elucidate the role of microbiota in regulating PSA levels.

Association between serum prostate-specific antigen concentrations and the risk of developing type 2 diabetes mellitus in Chinese men: A cohort study

AIMS/INTRODUCTION

The current literature suggests that men with diabetes have a lower prostate-specific antigen concentration than men without diabetes, but the causal association remains unclear. We aimed to investigate the association between serum prostate-specific antigen concentrations and the risk of type 2 diabetes mellitus in a cohort study of a Chinese population.

MATERIALS AND METHODS

We designed a cohort study that comprised 16,811 initially non-diabetic Chinese men who received annual health checkups between 2009 and 2016. The outcome of this study was type 2 diabetes mellitus, identified by medical diagnosis, self-reportage, medication use, fasting glucose, 2-h post oral glucose or glycated hemoglobin measurements. Cox proportional hazards models were carried out to evaluate the association.

RESULTS

During a median follow-up period of 3.8 years (interquartile range 1.91-5.73 years), 1,260 participants developed incident type 2 diabetes mellitus. The multivariable model, adjusted for various potential confounders, showed that serum prostate-specific antigen concentrations were inversely related to type 2 diabetes mellitus risk (P for trend = 0.014). Compared with the lowest quartile of serum prostate-specific antigen, the hazard ratio and 95% confidence intervals of type 2 diabetes mellitus risk for quartile 2-4 were 0.84 (0.66-1.07), 0.75 (0.59-0.94) and 0.77 (0.62-0.96), respectively. Subgroup analyses suggested the inverse relationship was more prominent in overweight or obese participants (P for interaction = 0.013).

CONCLUSIONS

High serum prostate-specific antigen concentration was associated with a low risk of type 2 diabetes mellitus in Chinese men. Future studies are required to confirm these findings and investigate underlying mechanisms.

The role of the p90 ribosomal S6 kinase family in prostate cancer progression and therapy resistance

Prostate cancer (PCa) is the second most commonly occurring cancer in men, with over a million new cases every year worldwide. Tumor growth and disease progression is mainly dependent on the Androgen Receptor (AR), a ligand dependent transcription factor. Standard PCa therapeutic treatments include androgen-deprivation therapy and AR signaling inhibitors. Despite being successful in controlling the disease in the majority of men, the high frequency of disease progression to aggressive and therapy resistant stages (termed castrate resistant prostate cancer) has led to the search for new therapeutic targets. The p90 ribosomal S6 kinase (RSK1-4) family is a group of highly conserved Ser/Thr kinases that holds promise as a novel target. RSKs are effector kinases that lay downstream of the Ras/Raf/MEK/ERK signaling pathway, and aberrant activation or expression of RSKs has been reported in several malignancies, including PCa. Despite their structural similarities, RSK isoforms have been shown to perform nonredundant functions and target a wide range of substrates involved in regulation of transcription and translation. In this article we review the roles of the RSKs in proliferation and motility, cell cycle control and therapy resistance in PCa, highlighting the possible interplay between RSKs and AR in mediating disease progression. In addition, we summarize the current advances in RSK inhibitor development and discuss their potential clinical benefits.

Androgen receptor signalling confers clonogenic and migratory advantages in urothelial cell carcinoma of the bladder

Bladder urothelial cell carcinoma (UCC) incidence is about three times higher in men compared with women. There are several indications for the involvement of hormonal factors in the aetiology of UCC. Here, we provide evidence of androgen signalling in UCC progression. Microarray and qPCR analysis revealed that the androgen receptor (AR) mRNA level is upregulated in a subset of UCC cases. In an AR‐positive UCC‐derived cell line model, UM‐UC‐3‐AR, androgen treatment increased clonogenic capacity inducing the formation of big stem cell‐like holoclones, while AR knockdown or treatment with the AR antagonist enzalutamide abrogated this clonogenic advantage. Additionally, blockage of AR signalling reduced the cell migration potential of androgen‐stimulated UM‐UC‐3‐AR cells. These phenotypic changes were accompanied by a rewiring of the transcriptome with almost 300 genes being differentially regulated by androgens, some of which correlated with AR expression in UCC patients in two independent data sets. Our results demonstrate that AR signals in UCC favouring the development of an aggressive phenotype and highlights its potential as a therapeutic target for bladder cancer.

Circulating insulin-like growth factor-I, total and free testosterone concentrations and prostate cancer risk in 200 000 men in UK Biobank

Insulin-like growth factor-I (IGF-I) and testosterone have been implicated in prostate cancer aetiology. Using data from a large prospective full-cohort with standardised assays and repeat blood measurements, and genetic data from an international consortium, we investigated the associations of circulating IGF-I, sex hormone-binding globulin (SHBG), and total and calculated free testosterone concentrations with prostate cancer incidence and mortality. For prospective analyses, risk was estimated using multivariable-adjusted Cox regression in 199 698 male UK Biobank participants. Hazard ratios (HRs) were corrected for regression dilution bias using repeat hormone measurements from a subsample. Two-sample Mendelian randomisation (MR) analysis of IGF-I and risk used genetic instruments identified from UK Biobank men and genetic outcome data from the PRACTICAL consortium (79 148 cases and 61 106 controls). We used cis- and all (cis and trans) SNP MR approaches. A total of 5402 men were diagnosed with and 295 died from prostate cancer (mean follow-up 6.9 years). Higher circulating IGF-I was associated with elevated prostate cancer diagnosis (HR per 5 nmol/L increment = 1.09, 95% CI 1.05-1.12) and mortality (HR per 5 nmol/L increment = 1.15, 1.02-1.29). MR analyses also supported the role of IGF-I in prostate cancer diagnosis (cis-MR odds ratio per 5 nmol/L increment = 1.34, 1.07-1.68). In observational analyses, higher free testosterone was associated with a higher risk of prostate cancer (HR per 50 pmol/L increment = 1.10, 1.05-1.15). Higher SHBG was associated with a lower risk (HR per 10 nmol/L increment = 0.95, 0.94-0.97), neither was associated with prostate cancer mortality. Total testosterone was not associated with prostate cancer. These findings implicate IGF-I and free testosterone in prostate cancer development and/or progression.

The helix-loop-helix transcriptional regulator Id4 is required for terminal differentiation of luminal epithelial cells in the prostate

Inhibitor of differentiation 4 (Id4), a member of the helix-loop-helix family of transcriptional regulators has emerged as a tumor suppressor in prostate cancer. In this study we investigated the effect of loss of Id4 (Id4-/-) on mouse prostate development. Histological analysis was performed on prostates from 25 days, 3 months and 6 months old Id4-/- mice. Expression of Amacr, Ck8, Ck18, Fkbp51, Fkbp52, androgen receptor, Pten, sca-1 and Nkx3.1 was investigated by immunohistochemistry. Results were compared to the prostates from Nkx3.1-/- mice. Id4-/- mice had smaller prostates with fewer and smaller tubules. Subtle PIN like lesions were observed at 6mo. Decreased Nkx3.1 and Pten and increased stem cell marker sca-1, PIN marker Amacr and basal cell marker p63 was observed at all ages. Persistent Ck8 and Ck18 expression suggested that loss of Id4 results in epithelial commitment but not terminal differentiation in spite of active Ar. Loss of Id4 attenuates normal prostate development and promotes hyperplasia/ dysplasia with PIN like lesions. The results suggest that loss of Id4 maintains stem cell phenotype of "luminal committed basal cells", identifying a unique prostate developmental pathway regulated by Id4.

Hormone-Dependent Prostate Cancers are Dependent on Rac Signaling for Growth and Survival

Prostate cancer remains a common cause of cancer mortality in men. Initially, cancers are dependent of androgens for growth and survival. First line therapies reduce levels of circulating androgens or target the androgen receptor (AR) directly. Although most patients show durable responses, many patients eventually progress to castration-resistant prostate cancer (CRPC) creating a need for alternative treatment options. The Rac1 signaling pathway has previously been implicated as a driver of cancer initiation and disease progression. We investigated the role of HACE1, the E3 ubiquitin ligase for Rac1, in prostate cancer and found that HACE1 is commonly lost resulting in hyperactive Rac signaling leading to enhanced cellular proliferation, motility and viability. Importantly, we show that a Rac inhibitor can attenuate the growth and survival of prostate cancer cells. Rac signaling was also found to be critical in prostate cancers that express the AR. Rac inhibition in androgen dependent cells resulted in reduction of AR target gene expression suggesting that targeting Rac1 may be an alternative method for blocking the AR signaling axis. Finally, when used in combination with AR antagonists, Rac inhibition enhanced the suppression of AR target gene expression. Therefore, targeting Rac in prostate cancer has the potential to enhance the efficacy of approved AR therapies.

MicroRNA-4287 is a novel tumor suppressor microRNA controlling epithelial-to mesenchymal transition in prostate cancer

Prostate cancer (PCa) is a significant cause of male morbidity in the United States. Despite recent advances in diagnosis and therapeutic interventions, significant fraction of cases still progress to an advanced stage. Various genetic/epigenetic elements that facilitate this progression are not yet completely known and the mechanism that favors advanced disease is an area of investigation. A characteristic feature associated with progressive disease is deletion of chromosome 8p (chr8p) region, that harbors tumor-suppressor NKX3.1. Previous studies from our group has shown that there are cluster of microRNAs (miRNAs) located within this region whose loss favors advanced, metastatic disease. miR-4287 is a novel miRNA located within this region that has not been studied before. In the present study, we analyzed the role of miR-4287 in PCa using clinical tissues and cell lines. We observed that miR-4287 is significantly downregulated in patient-derived tumor tissues. Receiver operating curve (ROC) analysis showed that miR-4287 distinguishes prostate cancer from normal with a specificity of 88.24% and with an Area under the curve (AUC) of 0.66. Further, we found that miR-4287 levels correlate inversely with patients' serum prostate-specific antigen levels. Ectopic over-expression of miR-4287 in PCa cell lines showed that miR-4287 plays a tumor suppressor role. miR-4287 led to an increase in G2/M phase of cell cycle in PCa cell lines. Further, ectopic miR-4287 inhibited PCa epithelial-to-mesenchymal transition (EMT) by directly repressing SLUG and stem cell marker CD44. Since miR-4287 specifically targets metastasis pathway mediators, miR-4287 has potential diagnostic and therapeutic significance in preventing advanced, metastatic disease.

Proteomic Profiling of Two Distinct Populations of Extracellular Vesicles Isolated from Human Seminal Plasma

Body fluids contain many populations of extracellular vesicles (EV) that differ in size, cellular origin, molecular composition, and biological activities. EV in seminal plasma are in majority originating from prostate epithelial cells, and hence are also referred to as prostasomes. Nevertheless, EV are also contributed by other accessory sex glands, as well as by the testis and epididymis. In a previous study, we isolated EV from seminal plasma of vasectomized men, thereby excluding contributions from the testis and epididymis, and identified two distinct EV populations with diameters of 50 and 100 nm, respectively. In the current study, we comprehensively analyzed the protein composition of these two EV populations using quantitative Liquid Chromatography-Mass Spectrometry (LC-MS/MS). In total 1558 proteins were identified. Of these, ≈45% was found only in the isolated 100 nm EV, 1% only in the isolated 50 nm EV, and 54% in both 100 nm and 50 nm EV. Gene ontology (GO) enrichment analysis suggest that both originate from the prostate, but with distinct biogenesis pathways. Finally, nine proteins, including KLK3, KLK2, MSMB, NEFH, PSCA, PABPC1, TGM4, ALOX15B, and ANO7, with known prostate specific expression and alternate expression levels in prostate cancer tissue were identified. These data have potential for the discovery of EV associated prostate cancer biomarkers in blood.

Prostate cancer recurrence mimicking invasive urothelial cancer of the bladder

A 74-year-old male patient with stage D1 prostate cancer with the initial prostate-specific antigen (PSA) level of 5570 ng/mL had received androgen deprivation therapy and the serum PSA level had decreased to 0.23 ng/mL when he developed macroscopic hematuria. MRI and cystoscopy suggested invasive urothelial cancer of the bladder, and transurethral resection was performed. The tumors were pathologically diagnosed as a Gleason score 9 prostate cancer with no PSA expression. Prostate cancer patients who develop novel symptoms should be screened for prostate cancer recurrence even if they have very low PSA levels.

A comparison of prostatic development in xenografts of human fetal prostate and human female fetal proximal urethra grown in dihydrotestosterone-treated hosts

The goal of this paper is to explore the ability of the human female urogenital sinus immediately below the bladder (proximal urethra) to undergo prostatic development in response to dihydrotestosterone (DHT). To establish this idea, xenografts of human fetal female proximal urethra were grown in castrated nude mouse hosts receiving a subcutaneous DHT pellet. To verify the prostatic nature of the resultant glands, DHT-treated human fetal female urethral xenografts were compared with human fetal prostatic xenografts (derived from male specimens) grown in untreated and DHT-treated castrated mouse hosts and human fetal female proximal urethral xenografts grown in untreated castrated hosts. The resultant glands observed in DHT-treated human fetal female proximal urethral xenografts expressed 3 prostate-specific markers, NKX3.1, prostate specific antigen and prostatic acid phosphatase as well as the androgen receptor. Glands induced by DHT exhibited a protein expression profile of additional immunohistochemical markers (seven keratins, RUNX1, ESR2, TP63 and FOXA1) consistent with the unique spatial pattern of these proteins in prostatic ducts. Xenografts of human fetal female proximal urethra grown in DHT-treated hosts also expressed one of the salient features of prostatic development, namely androgen responsiveness. The experimental induction of prostatic differentiation from human fetal female proximal urethra makes possible future in-depth analysis of the molecular pathways directly involved in initiation of human prostatic development and subsequent epithelial differentiation, and more important whether the molecular pathways involved in human prostatic development are similar/identical versus different from that in murine prostatic development.

miR-205: A Potential Biomedicine for Cancer Therapy

microRNAs (miRNAs) are a class of small non-coding RNAs that regulate the expression of their target mRNAs post transcriptionally. miRNAs are known to regulate not just a gene but the whole gene network (signaling pathways). Accumulating evidence(s) suggests that miRNAs can work either as oncogenes or tumor suppressors, but some miRNAs have a dual nature since they can act as both. miRNA 205 (miR-205) is one such highly conserved miRNA that can act as both, oncomiRNA and tumor suppressor. However, most reports confirm its emerging role as a tumor suppressor in many cancers. This review focuses on the downregulated expression of miR-205 and discusses its dysregulation in breast, prostate, skin, liver, gliomas, pancreatic, colorectal and renal cancers. This review also confers its role in tumor initiation, progression, cell proliferation, epithelial to mesenchymal transition, and tumor metastasis. Restoration of miR-205 makes cells more sensitive to drug treatments and mitigates drug resistance. Additionally, the importance of miR-205 in chemosensitization and its utilization as potential biomedicine and nanotherapy is described. Together, this review research article sheds a light on its application as a diagnostic and therapeutic marker, and as a biomedicine in cancer.

Histone Demethylase KDM7A Regulates Androgen Receptor Activity, and Its Chemical Inhibitor TC-E 5002 Overcomes Cisplatin-Resistance in Bladder Cancer Cells

Histone demethylase KDM7A regulates many biological processes, including differentiation, development, and the growth of several cancer cells. Here, we have focused on the role of KDM7A in bladder cancer cells, especially under drug-resistant conditions. When the KDM7A gene was knocked down, bladder cancer cell lines showed impaired cell growth, increased cell death, and reduced rates of cell migration. Biochemical studies revealed that KDM7A knockdown in the bladder cancer cells repressed the activity of androgen receptor (AR) through epigenetic regulation. When we developed a cisplatin-resistant bladder cancer cell line, we found that AR expression was highly elevated. Upon treatment with TC-E 5002, a chemical inhibitor of KDM7A, the cisplatin-resistant bladder cancer cells, showed decreased cell proliferation. In the mouse xenograft model, KDM7A knockdown or treatment with its inhibitor reduced the growth of the bladder tumor. We also observed the upregulation of KDM7A expression in patients with bladder cancer. The findings suggest that histone demethylase KDM7A mediates the growth of bladder cancer. Moreover, our findings highlight the therapeutic potential of the KMD7A inhibitor, TC-E 5002, in patients with cisplatin-resistant bladder cancer.

Computational analysis of androgen receptor (AR) variants to decipher the relationship between protein stability and related-diseases

Although more than 1,000 androgen receptor (AR) mutations have been identified and these mutants are pathologically important, few theoretical studies have investigated the role of AR protein folding stability in disease and its relationship with the phenotype of the patients. Here, we extracted AR variant data from four databases: ARDB, HGMD, Cosmic, and 1,000 genome. 905 androgen insensitivity syndrome (AIS)-associated loss-of-function mutants and 168 prostate cancer-associated gain-of-function mutants in AR were found. We analyzed the effect of single-residue variation on the folding stability of AR by FoldX and guanidine hydrochloride denaturation experiment, and found that genetic disease-associated mutations tend to have a significantly greater effect on protein stability than gene polymorphisms. Moreover, AR mutants in complete androgen insensitivity syndrome (CAIS) tend to have a greater effect on protein stability than in partial androgen insensitive syndrome (PAIS). This study, by linking disease phenotypes to changes in AR stability, demonstrates the importance of protein stability in the pathogenesis of hereditary disease.

An androgen-independent mechanism underlying the androgenic effects of 3-methylcholanthrene, a potent aryl hydrocarbon receptor agonist

Aryl hydrocarbon receptor (AhR) and androgen receptor (AR) are ligand-activated transcription factors with profound cross-talk between their signal transduction pathways. Previous studies have shown that AhR agonists activate the transcription of AR-regulated genes in an androgen-independent manner; however, the underlying mechanism remains unclear. To decipher this mechanism, we evaluated the effects of 3-methylcholanthrene (3MC), a potent AhR agonist, on the transcription of AR-regulated genes in three AR-expressing cell lines. 3MC induced the expression of not only three representative AR-regulated chromosomal genes but also the exogenous AR-responsive luciferase reporter gene. No significant difference in the 3MC-induced luciferase activity was detected in the presence of SKF-525A, a non-specific inhibitor of CYP enzymes. The androgenic effects of 3MC were diminished by AhR and AR knockdown. Following 3MC treatment, the amount of nuclear AhR and AR increased synchronously. Co-immunoprecipitation revealed that AhR and AR formed a complex in the nucleus of cells treated with 3MC. AR was recruited to the proximal promoter and distal enhancer regions of the PSA gene upon the addition of 3MC. We propose that AhR activated by 3MC forms a complex with unliganded AR which translocates from the cytoplasm to the nucleus. Nuclear AR now binds the transcriptional regulatory region of AR-regulated genes and activates the transcription.

Association between prostate-specific antigen and serum testosterone: A systematic review and meta-analysis

BACKGROUND

Serum testosterone assays are an important tool in the clinical evaluation of a number of endocrine disorders including male hypogonadism. However, serum testosterone has a limited role in real clinical use due to its inaccuracy. We aimed to assess the association between prostate-specific antigen (PSA) and testosterone as well as the effects of various types of testosterone replacement therapy (TRT) for PSA level.

METHODS

Two electronic databases were screened: PubMed (1966 through December 2018) and Cochrane Library (1993 through December 2018). The first strategy compared the overall increase in PSA following testosterone treatment compared with placebo. The second strategy analyzed the overall association between PSA and testosterone among the observational studies.

RESULTS

In the first strategy, 22 articles were included in the final analysis. In the second strategy, 18 studies were included. Testosterone replacement therapy (TRT) showed a significant change in PSA level compared to that in the placebo group (mean difference [MD]: 0.13, 95% CI: 0.01-0.25, P = .04). Compared to placebo, only intramuscular (IM) TRT shows a significant change in PSA level group (MD: 0.16, 95% CI: 0.01-0.30, P = .04), as neither the oral nor topical type showed a significant change in PSA. In the second strategy analysis, there was no overall correlation found between PSA and testosterone (z = 0.04, 95% CI: -0.04 to 0.12, P = .04; r = 0.039). However, in the subgroup of non-BPH (benign prostate hyperplasia), a significant correlation between PSA and testosterone (z = 0.07, 95% CI: 0.01-0.13, P = .009; r = 0.089) was found.

CONCLUSIONS

We found that TRT, particularly IM TRT, significantly changed the PSA level compared with the placebo group. Furthermore, there was a significant correlation between PSA and testosterone in patients with non-BPH. According to these findings, we suggest the possibility of PSA as a surrogate marker of testosterone.

Understanding Failure and Improving Treatment Using HDAC Inhibitors for Prostate Cancer

Novel treatment regimens are required for castration-resistant prostate cancers (CRPCs) that become unresponsive to standard treatments, such as docetaxel and enzalutamide. Histone deacetylase (HDAC) inhibitors showed promising results in hematological malignancies, but they failed in solid tumors such as prostate cancer, despite the overexpression of HDACs in CRPC. Four HDAC inhibitors, vorinostat, pracinostat, panobinostat and romidepsin, underwent phase II clinical trials for prostate cancers; however, phase III trials were not recommended due to a majority of patients exhibiting either toxicity or disease progression. In this review, the pharmacodynamic reasons for the failure of HDAC inhibitors were assessed and placed in the context of the advancements in the understanding of CRPCs, HDACs and resistance mechanisms. The review focuses on three themes: evolution of androgen receptor-negative prostate cancers, development of resistance mechanisms and differential effects of HDACs. In conclusion, advancements can be made in this field by characterizing HDACs in prostate tumors more extensively, as this will allow more specific drugs catering to the specific HDAC subtypes to be designed.

DUSP22 suppresses prostate cancer proliferation by targeting the EGFR-AR axis

Dual-specificity phosphatases (DUSPs) regulate the activity of various downstream kinases through serine or threonine or tyrosine dephosphorylation. Loss of function and aberrant expression of DUSPs has been implicated in cancer progression and poor survival, yet the function of DUSP22 in prostate cancer (PCa) cells is not clear. Gene Expression Omnibus and cBioPortal microarray database analyses showed that DUSP22 expression was lower in PCa tissues than normal prostate tissues, and altered DUSP22 expression was associated with shorter progression-free and disease-free survival of patients with PCa. Exogenous DUSP22 expression in LNCaP, PC3, and C4-2B PCa cells inhibited cellular proliferation and colony formation, supporting a growth inhibitory role for DUSP22 in PCa cells. DUSP22 expression significantly attenuated epidermal growth factor (EGF) receptor (EGFR) and its downstream ERK1/2 signaling by dephosphorylation. However, DUSP22 failed to suppress the growth of CWR22Rv1 and DU145 cells with elevated phosphorylated (p-)ERK1/2 levels. A serine-to-alanine mutation at position 58, a potential ERK1/2-targeted phosphorylation site in DUSP22, was sufficient to suppress growth of CWR22Rv1 cells with elevated p-ERK1/2 levels, suggesting a mutually antagonistic relationship between DUSP22 and ERK1/2 dependent on phosphorylation status. We showed that DUSP22 can suppress prostate-specific antigen gene expression through phosphatase-dependent pathways, suggesting that DUSP22 is an important regulator of the androgen receptor (AR) in PCa cells. Mechanistically, DUSP22 can interact with AR as a regulatory partner and interfere with EGF-induced AR phosphorylation at Tyr534, suggesting that DUSP22 serves as a crucial suppressor of both EGFR and AR-dependent signaling in PCa cells via dephosphorylation. Our findings indicate that loss of function of DUSP22 in PCa cells leads to aberrant activation of both EGFR-ERKs and AR signaling and ultimately progression of PCa, supporting the potential for novel therapeutic design of harnessing DUSP22 in the treatment of PCa.-Lin, H.-P., Ho, H.-M., Chang, C.-W., Yeh, S.-D., Su, Y.-W., Tan, T.-H., Lin, W.-J. DUSP22 suppresses prostate cancer proliferation by targeting the EGFR-AR axis.

Loss of Fibroblast-Dependent Androgen Receptor Activation in Prostate Cancer Cells is Involved in the Mechanism of Acquired Resistance to Castration

Loss of androgen receptor (AR) dependency in prostate cancer (PCa) cells is associated with progression to castration-resistant prostate cancer (CRPC). The tumor stroma is enriched in fibroblasts that secrete AR-activating factors. To investigate the roles of fibroblasts in AR activation under androgen deprivation, we used three sublines of androgen-sensitive LNCaP cells (E9 and F10 cells: low androgen sensitivity; and AIDL cells: androgen insensitivity) and original fibroblasts derived from patients with PCa. We performed in vivo experiments using three sublines of LNCaP cells and original fibroblasts to form homotypic tumors. The volume of tumors derived from E9 cells plus fibroblasts was reduced following androgen deprivation therapy (ADT), whereas that of F10 or AIDL cells plus fibroblasts was increased even after ADT. In tumors derived from E9 cells plus fibroblasts, serum prostate-specific antigen (PSA) decreased rapidly after ADT, but was still detectable. In contrast, serum PSA was increased even in F10 cells inoculated alone. In indirect cocultures with fibroblasts, PSA production was increased in E9 cells. Epidermal growth factor treatment stimulated Akt and p44/42 mitogen-activated protein kinase phosphorylation in E9 cells. Notably, AR splice variant 7 was detected in F10 cells. Overall, we found that fibroblast-secreted AR-activating factors modulated AR signaling in E9 cells after ADT and loss of fibroblast-dependent AR activation in F10 cells may be responsible for CRPC progression.

Phase I trial of TAK-385 in hormone treatment-naïve Japanese patients with nonmetastatic prostate cancer

This open‐label, phase I dose‐finding study evaluated the gonadotropin‐releasing hormone antagonist, TAK‐385, in Japanese patients with nonmetastatic prostate cancer. In a two‐part design, patients received daily oral TAK‐385 at doses of 320 (loading, day 1)/80 (maintenance, day 2 and thereafter), 320/120, 320/160, or 360/120 mg for 28 days in a dose‐escalation phase (part A, n = 13), and at 320/80 or 320/120 mg for up to 96 weeks in a randomized expansion phase (part B, n = 30). Primary endpoint in both parts was safety, including dose‐limiting toxicity in part A. Secondary endpoints included pharmacokinetics, pharmacodynamics, and prostate‐specific antigen concentration. Ten (77%) patients in part A and all patients in part B experienced an adverse event; hot flush (part A, n = 4; part B, n = 15), viral upper respiratory tract infection (part A, n = 1; part B, n = 10), and diarrhea (part B, n = 8) were most frequent. No dose‐limiting toxicities were observed (part A). In 12 evaluable patients (part A), TAK‐385 was rapidly absorbed after a single loading dose; on day 28 (maintenance dose), median steady‐state T_max was ~1‐2 hours and mean t_1/2z was 67‐79 hours. All doses rapidly reduced testosterone concentrations to castration levels within 1 week. Durable reductions in prostate‐specific antigen of >90% from baseline were observed through 96 weeks. TAK‐385 appeared tolerable and resulted in sustained reductions in testosterone to castration levels at all doses. The lowest loading/maintenance dose required for a clinical effect was 320/80 mg.

http://ClinicalTrials.gov: NCT02141659.

CCN3/Nephroblastoma Overexpressed Is a Functional Mediator of Prostate Cancer Bone Metastasis That Is Associated with Poor Patient Prognosis

Prostate cancer (PC) commonly metastasizes to the bone, resulting in pathologic fractures and poor prognosis. CCN3/nephroblastoma overexpressed is a secreted protein with a known role in promoting breast cancer metastasis to bone. However, in PC, CCN3 has been ascribed conflicting roles; some studies suggest that CCN3 promotes PC metastasis, whereas others argue a tumor suppressor role for CCN3 in this disease. Indeed, in the latter context, CCN3 has been shown to sequester the androgen receptor (AR) and suppress AR signaling. In the present study, we demonstrate that CCN3 functions as a bone-metastatic mediator, which is dependent on its C-terminal domain for this function. Analysis of tissue microarrays comprising >1500 primary PC patient radical prostatectomy specimens reveals that CCN3 expression correlates with aggressive disease and is negatively correlated with the expression of prostate-specific antigen, a marker of AR signaling. Together, these findings point to CCN3 as a biomarker to predict PC aggressiveness while providing clarity on its role as a functional mediator of PC bone metastasis.

Interaction between leukocyte aldo-keto reductase 1C3 activity, genotypes, biological, lifestyle and clinical features in a prostate cancer cohort from New Zealand

Introduction

Aldo-keto reductase 1C3 (AKR1C3) is known for multiple functions including its catalytic activity towards producing extra-testicular androgen. The present study is towards understanding interaction between biological, lifestyle and genetic impacts of AKR1C3 and their influence on clinical factors in a prostate cancer (PC) cohort from New Zealand (NZ).

Method

Characteristics of 516 PC patients were collected from the Auckland Regional Urology Facility, NZ. These men were genotyped for the AKR1C3 rs12529 single nucleotide polymorphism (SNP). The leukocyte AKR1C3 activity was measured in a sub-cohort. Variability of leukocyte AKR1C3 activity between biological, lifestyle and clinical features as well as correlation between biological and clinical features were assessed with and without genetic stratification.

Results

The leukocyte AKR1C3 activity was associated with age at diagnosis (0.51 vs 0.34 μM coumberol units for >69y vs ≤69y, P = 0.03); and with anatomic stage/prognostic grouping among the AKR1C3 rs12529 CC genotype carriers (0.50 vs 28 μM coumberol units among low- and high-risk groups respectively, P = 0.02). Significant correlation between leukocyte AKR1C3 activity and age at PC diagnosis was also observed (correlation coefficient 0.20 and P = 0.02). Ever- smoking impacted both age and PSA at PC diagnosis among AKR1C3 rs12529 GG and CG genotype carriers respectively. Age at diagnosis significantly correlated with PSA at diagnosis in the main (correlation coefficient 0.29, and P<0.001) and sub-cohorts (correlation coefficient 0.24, and P = 0.01); and those carrying the AKR1C3 rs12529 CG and GG genotypes in both the main (correlation coefficient 0.30, and P<0.001 and correlation coefficient 0.35, and P<0.001 respectively) and sub-cohorts (correlation coefficient 0.43, and P<0.001 and correlation coefficient 0.39, and P = 0.06 respectively); but not with those carrying the CC genotype.

Conclusions

Age dependent PSA thresholds in PC screening could have been valid only in men carrying the AKR1C3 rs12529 CG and GG genotypes in this NZ cohort.

MicroRNA-3162-5p-Mediated Crosstalk between Kallikrein Family Members Including Prostate-Specific Antigen in Prostate Cancer

BACKGROUND

MicroRNAs mediate biological processes through preferential binding to the 3' untranslated region (3' UTR) of target genes. Studies have shown their association with prostate cancer (PCa) risk through single-nucleotide polymorphisms (SNPs), known as miRSNPs. In a European cohort, 22 PCa risk-associated miRSNPs have been identified. The most significant miRSNP in the 3' UTR of Kallikrein-related peptidase 3 (KLK3) created a binding site for miR-3162-5p. Here we investigated the miR-3162-5p-KLK interaction and the clinical implication of miR-3162-5p in PCa.

METHODS

We tested the role of miR-3162-5p in PCa etiology using IncuCyte live-cell imaging and anchorage-independent growth assays. The effect of miR-3162-5p on KLK and androgen receptor (AR) expression was measured by RT-quantitative (q)PCR and target pulldown assays. KLK3 proteolytic activity was determined by DELFIA^® immunoassay. Mass spectrometry identified pathways affected by miR-3162-5p. miR-3162-5p expression was measured in clinical samples using RT-qPCR.

RESULTS

miR-3162-5p affected proliferation, migration, and colony formation of LNCaP cells by regulating the expression of KLK2-4 and AR by direct targeting. KLK3 protein expression was regulated by miR-3162-5p consistent with lower KLK3 proteolytic activity observed in LNCaP-conditioned media. KLK/AR pulldown and mass spectrometry analysis showed a potential role of miR-3162-5p in metabolic pathways via KLK/AR and additional targets. Increased miR-3162-5p expression was observed in prostate tumor tissues with higher Gleason grade.

CONCLUSIONS

Our study provides an insight into possible involvement of miR-3162-5p in PCa etiology by targeting KLKs and AR. It highlights clinical utility of miR-3162-5p and its interactive axis as a new class of biomarkers and therapeutic targets for PCa.

RNA-based markers in biopsy cores with atypical small acinar proliferation: Predictive effect of T2E fusion positivity and MMP-2 upregulation for a subsequent prostate cancer diagnosis

BACKGROUND

Atypical small acinar proliferation (ASAP) is a precursor lesion of prostate cancer (PC), and PC develops from this suspicious focus or an unsampled malignant gland nearby. However, PC-related molecular alterations that could guide the timing of repeat biopsies and help monitor PC risk in ASAP-diagnosed patients have not been investigated. The purpose of this study was to first investigate the expression of seven different PC-related RNAs that included serine 2 (TMPRSS2): erythroblastosis virus E26 oncogene homolog (ERG) gene (TMPRSS2-ERG, T2E) fusion, alpha-methylacyl-CoA racemase (AMACR), kallikrein related peptidase 3 (KLK3), androgen receptor (AR), prostate cancer specific antigen 3 (PCA3), and matrix metalloproteinases (MMP)-2 and 9.

METHODS

PC-related RNAs were evaluated using a real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) system in pathologically ASAP-diagnosed prostate biopsy cores from 55 patients presenting with a normal digital rectal examination and a PSA level of 4-10 ng/mL.

RESULTS

We detected that positive T2E fusion status (P = 0.013) and the expression of AMACR (P = 0.016), AR (P = 0.016) and MMP-2 (P = 0.013) were independently and significantly associated with PC risk in ASAP patients. There were also several statistically significant correlations between expression levels. Additionally, we demonstrated that T2E fusion positive ASAP patients with higher MMP-2 expression were more likely to be diagnosed with PC at a subsequent biopsy during the follow-up period (P = 0.003).

CONCLUSIONS

Although, more clinical validations are needed for the stratification of PC risk in ASAP-diagnosed biopsy cores, our current results indicate that the coexistence of T2E fusion positivity with MMP-2 upregulation may help clinicians adjust their biopsy timetable and/or assessment of PC risk in ASAP-diagnosed patients with a PSA level of 4-10 ng/mL.

The Importance of Time to Prostate-Specific Antigen (PSA) Nadir after Primary Androgen Deprivation Therapy in Hormone-Naïve Prostate Cancer Patients

Prostate-specific antigen (PSA) is currently the most useful biomarker for detection of prostate cancer (PCa). The ability to measure serum PSA levels has affected all aspects of PCa management over the past two decades. The standard initial systemic therapy for advanced PCa is androgen-deprivation therapy (ADT). Although PCa patients with metastatic disease initially respond well to ADT, they often progress to castration-resistant prostate cancer (CRPC), which has a high mortality rate. We have demonstrated that time to PSA nadir (TTN) after primary ADT is an important early predictor of overall survival and progression-free survival for advanced PCa patients. In in vivo experiments, we demonstrated that the presence of fibroblasts in the PCa tumor microenvironment can prolong the period for serum PSA decline after ADT, and enhance the efficacy of ADT. Clarification of the mechanisms that affect TTN after ADT could be useful to guide selection of optimal PCa treatment strategies. In this review, we discuss recent in vitro and in vivo findings concerning the involvement of stromal–epithelial interactions in the biological mechanism of TTN after ADT to support the novel concept of “tumor regulating fibroblasts”.