Purinergic smooth muscle contractions in the human prostate: estimation of relevance and characterization of different agonists

Effects of carvedilol on human prostate tissue contractility and stromal cell growth pointing to potential clinical implications

BACKGROUND

Apart from antagonizing ß-adrenoceptors, carvedilol antagonizes vascular α1-adrenoceptors and activates G protein-independent signaling. Even though it is a commonly used antihypertensive and α1-adrenoceptors are essential for the treatment of voiding symptoms in benign prostatic hyperplasia, its actions in the human prostate are still unknown. Here, we examined carvedilol effects on contractions of human prostate tissues, and on stromal cell growth.

METHODS

Contractions of prostate tissues from radical prostatectomy were induced by electric field stimulation (EFS) or α1-agonists. Growth-related functions were examined in cultured stromal cells.

RESULTS

Concentration-response curves for phenylephrine, methoxamine and noradrenaline were right shifted by carvedilol (0.1-10 µM), around half a magnitude with 100 nM, half to one magnitude with 1 µM, and two magnitudes with 10 µM. Right shifts were reflected by increased EC50 values for agonists, with unchanged Emax values. EFS-induced contractions were reduced by 21-54% with 0.01-1 µM carvedilol, and by 94% by 10 µM. Colony numbers of stromal cells were increased by 500 nM, but reduced by 1-10 µM carvedilol, while all concentrations reduced colony size. Decreases in viability were time-dependent with 0.1-0.3 µM, but complete with 10 µM. Proliferation was slightly increased by 0.1-0.5 µM, but reduced with 1-10 µM.

CONCLUSIONS

Carvedilol antagonizes α1-adrenoceptors in the human prostate, starting with concentrations in ranges of known plasma levels. In vitro, effect sizes resemble those of α1-blockers used for the treatment of voiding symptoms, which requires concentrations beyond plasma levels. Bidirectional and dynamic effects on the growth of stromal cells may be attributed to "biased agonism".

Double-modified, thio and methylene ATP analogue facilitates wound healing in vitro and in vivo

Recent data indicate that extracellular ATP affects wound healing efficacy via P2Y2-dependent signaling pathway. In the current work, we propose double-modified ATP analogue-alpha-thio-beta,gamma-methylene-ATP as a potential therapeutic agent for a skin regeneration. For the better understanding of structure-activity relationship, beside tested ATP analogues, the appropriate single-modified derivatives of target compound, such as alpha-thio-ATP and beta,gamma-methylene-ATP, were also tested in the context of their involvement in the activation of ATP-dependent purinergic signaling pathway via the P2Y2 receptor. The diastereomerically pure alpha-thio-modified-ATP derivatives were obtained using the oxathiaphospholane method as separate SP and RP diastereomers. Both the single- and double- modified ATP analogues were then tested for their impact on the viability and migration of human keratinocytes. The involvement of P2Y2-dependent purinergic signaling was analyzed in silico by molecular docking of the tested compounds to the P2Y2 receptor and experimentally by studying intracellular calcium mobilization in the human keratinocytes HaCaT. The effects obtained for ATP analogues were compared with the results for ATP as a natural P2Y2 agonist. To confirm the contribution of the P2Y2 receptor to the observed effects, the tests were also performed in the presence of the selective P2Y2 antagonist-AR-C118925XX. The ability of the alpha-thio-beta,gamma-methylene-ATP to influence cell migration was analyzed in vitro on the model HaCaT and MDA-MB-231 cells by wound healing assay and transwell migration test as well as in vivo using zebrafish system. The impact on tissue regeneration was estimated based on the regrowth rate of cut zebrafish tails. The in vitro and in vivo studies have shown that the SP-alpha-thio-beta,gamma-methylene-ATP analogue promotes regeneration-related processes, making it a suitable agent for enhance wound healing. Performed studies indicated its impact on the cell migration, induction of epithelial-mesenchymal transition and intracellular calcium mobilization. The enhanced regeneration of cut zebrafish tails confirmed the pro-regenerative activity of this ATP analogue. Based on the performed studies, the SP-alpha-thio-beta,gamma-methylene-ATP is proposed as a potential therapeutic agent for wound healing and skin regeneration treatment.

Isoform-independent promotion of contractility and proliferation, and suppression of survival by with no lysine/K kinases in prostate stromal cells

With no lysine/K kinases (WNKs) promote vasocontraction and vascular smooth muscle cell proliferation. In the prostate, smooth muscle contraction and growth may be critical for the development and medical treatment of voiding symptoms in benign prostatic hyperplasia. Here, we examined the effects of isoform-specific WNK silencing and of the WNK inhibitor WNK463 on growth-related functions and contraction in prostate stromal cells, and in human prostate tissues. Impacts of WNK silencing by transfection of cultured stromal cells with isoform-specific siRNAs were qualitatively and quantitatively similar for each WNK isoform. Effects of silencing were largest on cell death (3-5 fold increase in annexin V-positive/7-AAD-positive cells), on proliferation rate, Ki-67 mRNA expression and actin organization (reduced around two-thirds). Contraction in matrix contraction assays and viability were reduced to a lower degree (approximately half), but again to a similar extent for each WNK isoform. Effects of silencing were quantitatively and qualitatively reproduced by 10 μM WNK463, while 1 μM still induced cell death and breakdown in actin organization, without affecting proliferation or viability. Using 500 nM and 10 μM, WNK463 partly inhibited neurogenic and U46619-induced contractions of human prostate tissues (around half), while inhibition of α1-adrenergic contractions (around half) was limited to 10 μM. All four WNK isoforms suppress cell death and promote proliferation in prostate stromal cells. WNK-driven contraction of stromal cells appears possible, even though to a limited extent. Outcomes of isoform-specific WNK silencing can be fully reproduced by WNK463, including inhibition of smooth muscle contraction in human prostate tissues, but require high concentrations.

Alteration of the Expression and Functional Activities of Myosin II Isoforms in Enlarged Hyperplastic Prostates

INTRODUCTION

Benign prostatic hyperplasia (BPH) is a common pathologic process in aging men, and the contraction of the prostatic smooth muscles (SMs) in the stroma plays a vital role in this pathogenesis, leading to lower urinary tract symptoms (LUTSs). The isoforms of both the SM myosin (SMM) and non-muscle myosin (NMM) are associated with the contraction type of the prostatic SMs, but the mechanism has not been fully elucidated.

METHODS

We collected prostate tissues from 30 BPH patients receiving surgical treatments, and normal human prostate samples were obtained from 12 brain-dead men. A testosterone-induced (T-induced) rat model was built, and the epithelial hyperplastic prostates were harvested. Competitive RT-PCR was used to detect the expression of SMM isoforms. We investigated the contractility of human prostate strips in vitro in an organ bath.

RESULTS

The results regarding the comparisons of SMM isoforms varied between rat models and human samples. In comparison with T-induced rats and controls, competitive RT-PCR failed to show any statistically significant difference regarding the compositions of SMM isoforms. For human prostates samples, BPH patients expressed more SM-1 isoforms (66.8% vs. 60.0%, p < 0.001) and myosin light chain-17b (MLC17b) (35.9% vs. 28.5%, p < 0.05) when compared to young donors. There was a significant decrease in prostate myosin heavy chain (MHC) expression in BPH patients, with a 66.4% decrease in MHC at the mRNA level and a 51.2% decrease at the protein level. The upregulated expression of non-muscle myosin heavy chain-B (NMMHC-B) was 1.6-fold at the mRNA level and 2.1-fold at the protein level. The organ bath study showed that isolated prostate strips from BPH patients produced slower tonic contraction compared to normal humans.

CONCLUSION

In this study, we claim that in the enlarged prostates of patients undergoing surgeries, MHC expression significantly decreased compared to normal tissues, with elevated levels of SM-1, MLC17b, and NMMHC-B isoforms. Modifications in SMM and NMM might play a role in the tonic contractile properties of prostatic SMs and the development of LUTS/BPH. Understanding this mechanism might provide insights into the origins of LUTS/BPH and facilitate the identification of novel therapeutic targets.

Extracellular nucleotides in smooth muscle contraction

Extracellular nucleotides and nucleosides are crucial signalling molecules, eliciting diverse biological responses in almost all organs and tissues. These molecules exert their effects by activating specific nucleotide receptors, which are finely regulated by ectonucleotidases that break down their ligands. In this comprehensive review, we aim to elucidate the relevance of extracellular nucleotides as signalling molecules in the context of smooth muscle contraction, considering the modulatory influence of ectonucleotidases on this intricate process. Specifically, we provide a detailed examination of the involvement of extracellular nucleotides in the contraction of non-vascular smooth muscles, including those found in the urinary bladder, the airways, the reproductive system, and the gastrointestinal tract. Furthermore, we present a broader overview of the role of extracellular nucleotides in vascular smooth muscle contraction.

Adrenoceptors in the Lower Urinary Tract

Adrenoceptors importantly contribute to the physiological regulation of lower urinary tract (LUT) function and have become a target of several clinically successful treatments for major LUT diseases. In the bladder dome, β-adrenoceptor subtypes are found in multiple cell types and mediate relaxation of detrusor smooth muscle, perhaps partly indirectly by acting on afferent nerves and cells of the mucosa. β₃-adrenoceptor agonists such as mirabegron and vibegron are used to treat overactive bladder syndrome. In the bladder trigone and urethra, α₁-adrenoceptors cause contraction and thereby physiologically contribute to bladder outlet resistance. α₁-adrenoceptors in the prostate also cause contraction and pathophysiologically elevate bladder outlet resistance leading to voiding dysfunction in benign prostatic hyperplasia. α₁-adrenoceptor antagonist such as tamsulosin is widely used as a first-line option to treat LUT symptoms in men, but it remains unclear to which extent and how smooth muscle relaxation contributes to symptom relief.

Inhibition of α1-Adrenergic, Non-Adrenergic and Neurogenic Human Prostate Smooth Muscle Contraction and of Stromal Cell Growth by the Isoflavones Genistein and Daidzein

Isoflavone-rich legumes, including soy, are used for food production, as dietary supplements and in traditional medicine. Soy consumption correlates negatively with benign prostatic hyperplasia (BPH) and voiding symptoms. However, isoflavone effects on the prostate are hardly known. Here, we examined the effects on human prostate smooth muscle contractions and stromal cell growth, which are driving factors of voiding symptoms in BPH. Smooth muscle contractions were induced in prostate tissues from radical prostatectomy. Growth-related functions were studied in cultured stromal cells (WPMY-1). Neurogenic, α1-adrenergic and non-adrenergic contractions were strongly inhibited with 50 µM and by around 50% with 10 µM genistein. Daidzein inhibited neurogenic contractions using 10 and 100 µM. Agonist-induced contractions were inhibited by 100 µM but not 10 µM daidzein. A combination of 6 µM genistein with 5 µM daidzein still inhibited neurogenic and agonist-induced contractions. Proliferation of WPMY-1 cells was inhibited by genistein (>50%) and daidzein (<50%). Genistein induced apoptosis and cell death (by seven-fold relative to controls), while daidzein induced cell death (6.4-fold) without apoptosis. Viability was reduced by genistein (maximum: 87%) and daidzein (62%). In conclusion, soy isoflavones exert sustained effects on prostate smooth muscle contractions and stromal cell growth, which may explain the inverse relationships between soy-rich nutrition, BPH and voiding symptoms.

Permixon®, hexane-extracted Serenoa repens, inhibits human prostate and bladder smooth muscle contraction and exerts growth-related functions in human prostate stromal cells

AIMS

Recently, the European Association of Urology recommended hexane-extracted fruit of Serenoa repens (HESr) in their guidelines on management of non-neurogenic male lower urinary tracts symptoms (LUTS). Despite previously lacking recommendations, Permixon® is the most investigated HESr in clinical trials, where it proved effective for male LUTS. In contrast, underlying mechanisms were rarely addressed and are only marginally understood. We therefore investigated effects of Permixon® on human prostate and detrusor smooth muscle contraction and on growth-related functions in prostate stromal cells.

MAIN METHODS

Permixon® capsules were dissolved using n-hexane. Contractions of human prostate and detrusor tissues were induced in organ bath. Proliferation (EdU assay), growth (colony formation), apoptosis and cell death (flow cytometry), viability (CCK-8) and actin organization (phalloidin staining) were studied in cultured human prostate stromal cells (WPMY-1).

KEY FINDINGS

Permixon® inhibited α₁-adrenergic and thromboxane-induced contractions in prostate tissues, and methacholine-and thromboxane-induced contractions in detrusor tissues. Endothelin-1-induced contractions were not inhibited. Neurogenic contractions were inhibited in both tissues in a concentration-dependent manner. In WPMY-1 cells, Permixon® caused concentration-dependent breakdown of actin polymerization, inhibited colony formation, reduced cell viability, and proliferation, without showing cytotoxic or pro-apoptotic effects.

SIGNIFICANCE

Our results provide a novel basis that allows, for the first time, to fully explain the ubiquitous beneficial effects of HESr in clinical trials. HESr may inhibit at least neurogenic, α₁-adrenergic and thromboxane-induced smooth muscle contraction in the prostate and detrusor, and in parallel, prostate stromal cell growth. Together, this may explain symptom improvements by Permixon® in previous clinical trials.

The Potential of Purinergic Signaling to Thwart Viruses Including SARS-CoV-2

A long-shared evolutionary history is congruent with the multiple roles played by purinergic signaling in viral infection, replication and host responses that can assist or hinder viral functions. An overview of the involvement of purinergic signaling among a range of viruses is compared and contrasted with what is currently understood for SARS-CoV-2. In particular, we focus on the inflammatory and antiviral responses of infected cells mediated by purinergic receptor activation. Although there is considerable variation in a patient's response to SARS-CoV-2 infection, a principle immediate concern in Coronavirus disease (COVID-19) is the possibility of an aberrant inflammatory activation causing diffuse lung oedema and respiratory failure. We discuss the most promising potential interventions modulating purinergic signaling that may attenuate the more serious repercussions of SARS-CoV-2 infection and aspects of their implementation.

Antagonism of α1-adrenoceptors by β3-adrenergic agonists: Structure-function relations of different agonists in prostate smooth muscle contraction

Effects of β₃-adrenergic agonists on prostate smooth muscle contraction are poorly characterized, although mirabegron is used for treatment of lower urinary tract symptoms. Off-target effects of several β₃-adrenergic agonists include antagonism of α₁-adrenoceptors. Proposed, but unconfirmed explanations include phenylethanolamine backbones, found in some β₃-adrenergic agonists and imparting interaction with catecholamine binding pockets of adrenoceptors. Here, we examined effects of β₃-adrenergic agonists on contractions of human prostate tissues, including ZD7114 (without phenylethanolamine moiety), ZD2079 (phenylethanolamine backbone), BRL37344 and CL316243 (chloride-substituted phenylethanolamine deriatives). Prostate tissues were obtained from radical prostatectomy. Contractions by α₁-adrenergic agonists and electric field stimulation (EFS) were studied in an organ bath. ZD7114 (10 µM) right-shifted concentration responses curves for α₁-adrenergic agonists, resulting in increased EC₅₀ values for phenylephrine, methoxamine and noradrenaline up to one magnitude, without affecting E_max values. ZD7114 (10 µM) inhibited EFS-induced contractions, resulting in reduced E_max values. All effects of ZD7114 were resistant to the β₃-adrenergic antagonist L-748337, including increases in EC₅₀ values for α₁-adrenergic agonists, up to more than two magnitudes. Using 10 µM, neither ZD2079, BRL37344 or CL316243 affected α₁-adrenergic or EFS-induced contractions. At escalated concentrations, BRL37344 (200 µM) right-shifted concentration response curves for phenylephrine, increased EC₅₀ values for phenylephrine, and inhibited EFS-induced contractions, while CL316243 (300 µM) did not affect phenylephrine- or EFS-induced contractions. In conclusion, phenylethanolamine backbones are not decisive to impart α₁-adrenoceptor antagonism to β₃-agonists. Effects of β₃-adrenergic agonists on prostate smooth muscle contraction are limited to off-target effects, including α₁-adrenoceptor antagonism by ZD7114 and BRL37344.

Inhibition of Human Prostate and Bladder Smooth Muscle Contraction, Vasoconstriction of Porcine Renal and Coronary Arteries, and Growth-Related Functions of Prostate Stromal Cells by Presumed Small Molecule Gαq/11 Inhibitor, YM-254890

Introduction: Lower urinary tract symptoms (LUTS) involve benign prostatic hyperplasia (BPH) and overactive bladder (OAB). Standard-of-care medical treatment includes α1-blockers and antimuscarinics for reduction of prostate and detrusor smooth muscle tone, respectively, and 5α-reductase inhibitors (5-ARI) to prevent prostate growth. Current medications are marked by high discontinuation rates due to unfavourable balance between efficacy and treatment-limiting side effects, ranging from dry mouth for antimuscarinics to cardiovascular dysregulation and a tendency to fall for α1-blockers, which results from hypotension, due to vasorelaxation. Agonist-induced smooth muscle contractions are caused by activation of receptor-coupled G-proteins. However, little is known about receptor- and organ-specific differences in coupling to G-proteins. With YM-254890, a small molecule inhibitor with presumed specificity for Gαq/11 became recently available. Here, we investigated effects of YM-254890 on prostate, bladder and vascular smooth muscle contraction, and on growth-related functions in prostate stromal cells.

Methods: Contractions of human prostate and detrusor tissues, porcine renal and coronary arteries were induced in an organ bath. Proliferation (EdU assay), growth (colony formation), apoptosis and cell death (flow cytometry), viability (CCK-8) and actin organization (phalloidin staining) were studied in cultured human prostate stromal cells (WPMY-1).

Results: Contractions by α1-adrenergic agonists, U46619, endothelin-1, and neurogenic contractions were nearly completely inhibited by YM-254890 (30 nM) in prostate tissues. Contractions by cholinergic agonists, U46619, endothelin-1, and neurogenic contractions were only partly inhibited in detrusor tissues. Contractions by α1-adrenergic agonists, U46619, endothelin-1, and neurogenic contractions were strongly, but not fully inhibited in renal arteries. Contractions by cholinergic agonists were completely, but by U46619 and endothelin-1 only strongly inhibited, and neurogenic contractions reduced by half in coronary arteries. YM-254890 had no effect on agonist-independent contractions induced by highmolar (80 mM) potassium chloride (KCl). Neurogenic detrusor contractions were fully sensitive to tetrodotoxin. In WPMY-1 cells, YM-254890 caused breakdown of actin polymerization and organization, and obvious, but clearly limited decreases of proliferation rate, colony formation and viability, and slightly increased apoptosis.

Conclusion: Intracellular post-receptor signaling pathways are shared by Gαq-coupled contractile receptors in multiple smooth muscle-rich organs, but to different extent. While inhibition of Gαq/11 causes actin breakdown, anti-proliferative effects were detectable but clearly limited. Together this may aid in developing future pharmaceutical targets for LUTS and antihypertensive medication.

Inhibition of human prostate smooth muscle contraction by the inhibitors of protein kinase C, GF109203X, and Go6983

INTRODUCTION

Prostate smooth muscle contraction is promoted by receptor-induced activation of intracellular signaling pathways. The presumed involvement in etiology and medical treatment of lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia (BPH) imparts a high clinical relevance to prostate smooth muscle contraction, which is contrasted by incomplete understanding at the molecular level. Involvement of protein kinase C (PKC) has been commonly assumed, but available studies were limited to nonhuman prostate smooth muscle or cell cultures. Here, we examined the effects of the PKC inhibitors Go6983 and GF109203x on contractions of human prostate tissues.

METHODS

Prostate tissues were obtained from radical prostatectomy. Contractions were induced by electric field stimulation (EFS), α₁ -adrenergic agonists (noradrenaline, phenylephrine, methoxamine), thromboxane A₂ analog U46619, endothelin-1, or calcium chloride in an organ bath.

RESULTS

GF109203X (500 nM) and Go6983 (300  nM) reduced EFS-, noradrenaline-, phenylephrine-, methoxamine-, and U46619-induced contractions of human prostate tissues, with maximum inhibitions approaching up to 55%. Using concentrations of 3 µM, GF109203X and Go6983 inhibited EFS- and noradrenaline-induced contractions, with similar effect sizes as 500 and 300 nM, respectively. Endothelin-1-induced contractions were not inhibited by GF109203X, and to neglectable extent by Go6983. After depolarization in calcium-free solution, calcium chloride-induced concentration-dependent contractions, which were inhibited by GF109203X and Go6983.

CONCLUSIONS

GF109203X and Go6983 inhibit neurogenic, α₁ -adrenergic, and thromboxane A₂ -induced smooth muscle contractions in the human prostate, suggesting a role of PKC for human prostate smooth muscle contraction. The inhibition may by be imparted by inhibition of calcium sensitivity.

Concentration-dependent alpha1-Adrenoceptor Antagonism and Inhibition of Neurogenic Smooth Muscle Contraction by Mirabegron in the Human Prostate

Introduction: Mirabegron is available for treatment of storage symptoms in overactive bladder, which may be improved by β₃-adrenoceptor-induced bladder smooth muscle relaxation. In addition to storage symptoms, lower urinary tract symptoms in men include obstructive symptoms attributed to benign prostatic hyperplasia, caused by increased prostate smooth muscle tone and prostate enlargement. In contrast to the bladder and storage symptoms, effects of mirabegron on prostate smooth muscle contraction and obstructive symptoms are poorly understood. Evidence from non-human smooth muscle suggested antagonism of α₁-adrenoceptors as an important off-target effect of mirabegron. As α₁-adrenergic contraction is crucial in pathophysiology and medical treatment of obstructive symptoms, we here examined effects of mirabegron on contractions of human prostate tissues and on proliferation of prostate stromal cells.

Methods: Contractions were induced in an organ bath. Effects of mirabegron on proliferation, viability, and cAMP levels in cultured stromal cells were examined by EdU assays, CCK-8 assays and enzyme-linked immunosorbent assay.

Results: Mirabegron in concentrations of 5 and 10 μM, but not 1 µM inhibited electric field stimulation-induced contractions of human prostate tissues. Mirabegron in concentrations of 5 and 10 µM shifted concentration response curves for noradrenaline-, methoxamine- and phenylephrine-induced contractions to the right, including recovery of contractions at high concentrations of α₁-adrenergic agonists, increased EC₅₀ values, but unchanged E_max values. Rightshifts of noradrenaline concentration response curves and inhibition of EFS-induced contractions were resistant to L-748,337, l-NAME, and BPIPP. 1 µM mirabegron was without effect on α₁-adrenergic contractions. Endothelin-1- and U46619-induced contractions were not affected or only inhibited to neglectable extent. Effects of mirabegron (0.5–10 µM) on proliferation and viability of stromal cells were neglectable or small, reaching maximum decreases of 8% in proliferation assays and 17% in viability assays. Mirabegron did not induce detectable increases of cAMP levels in cultured stromal cells.

Conclusion: Mirabegron inhibits neurogenic and α₁-adrenergic human prostate smooth muscle contractions. This inhibition may be based on antagonism of α₁-adrenoceptors by mirabegron, and does not include activation of β₃-adrenoceptors and requires concentrations ranging 50-100fold higher than plasma concentrations reported from normal dosing. Non-adrenergic contractions and proliferation of prostate stromal cells are not inhibited by mirabegron.