Phosphodiesterase 5A regulates the vomeronasal pump in mice.

The vomeronasal organ (VNO) is a specialized chemoreceptive structure in many vertebrates that detects chemical stimuli, mostly pheromones, which often elicit innate behaviors such as mating and aggression. Previous studies in rodents have demonstrated that chemical stimuli are actively transported to the VNO via a blood vessel-based pumping mechanism, and this pumping mechanism is necessary for vomeronasal stimulation in behaving animals. However, the molecular mechanisms that regulate the vomeronasal pump remain mostly unknown. In this study, we observed a high level of expression of phosphodiesterase 5A (PDE5A) in the vomeronasal blood vessel of mice. We provided evidence to support the potential role of PDE5A in vomeronasal pump regulation. Local application of PDE5A inhibitors-sildenafil or tadalafil-to the vomeronasal organ (VNO) reduced stimulus delivery into the VNO, decreased the pheromone-induced activity of vomeronasal sensory neurons, and attenuated male-male aggressive behaviors. PDE5A is well known to play a role in regulating blood vessel tone in several organs. Our study advances our understanding of the molecular regulation of the vomeronasal pump.

CircPDE5A-encoded novel regulator of the PI3K/AKT pathway inhibits esophageal squamous cell carcinoma progression by promoting USP14-mediated de-ubiquitination of PIK3IP1.

BACKGROUND: Esophageal squamous cell carcinoma (ESCC) is a common gastrointestinal tumor and has become an important global health problem. The PI3K/AKT signaling pathway plays a key role in the development of ESCC. CircRNAs have been reported to be involved in the regulation of the PI3K/AKT pathway, but the underlying mechanisms are unclear. Therefore, this study aimed to identify protein-coding circRNAs and investigate their functions in ESCC. METHODS: Differential expression of circRNAs between ESCC tissues and adjacent normal tissues was identified using circRNA microarray analysis. Thereafter, LC-MS/MS was used to identify circPDE5A-encoded novel protein PDE5A-500aa. Molecular biological methods were used to explore the biological functions and regulatory mechanisms of circPDE5A and PDE5A-500aa in ESCC. Lastly, circRNA-loaded nanoplatforms were constructed to investigate the therapeutic translation value of circPDE5A. RESULTS: We found that circPDE5A expression was down-regulated in ESCC cells and tissues and that it was negatively associated with advanced clinicopathological stages and poorer prognosis in ESCC. Functionally, circPDE5A inhibited ESCC proliferation and metastasis in vitro and in vivo by encoding PDE5A-500aa, a key regulator of the PI3K/AKT signaling pathway in ESCC. Mechanistically, PDE5A-500aa interacted with PIK3IP1 and promoted USP14-mediated de-ubiquitination of the k48-linked polyubiquitin chain at its K198 residue, thereby attenuating the PI3K/AKT pathway in ESCC. In addition, Meo-PEG-S-S-PLGA-based reduction-responsive nanoplatforms loaded with circPDE5A and PDE5A-500aa plasmids were found to successfully inhibit the growth and metastasis of ESCC in vitro and in vivo. CONCLUSION: The novel protein PDE5A-500aa encoded by circPDE5A can act as an inhibitor of the PI3K/AKT signaling pathway to inhibit the progression of ESCC by promoting USP14-mediated de-ubiquitination of PIK3IP1 and may serve as a potential target for the development of therapeutic agents.

Hsa_circ_0092355 Accelerates Papillary Thyroid Cancer Progression by Regulating the miR-543/PDE5A Pathway.

CircRNAs have been found to participate in the progression of various tumors. In the present study, we aimed to clarify the role of hsa_circ_0092355 in papillary thyroid cancer (PTC) cell development. RT-qPCR was used to determine the expression of hsa_circ_0092355, miR-543, and PDE5A. PTC cell proliferation was ascertained via a cell colony formation assay and the CCK-8 test. Western blotting was performed to examine the expression levels of PDE5A and apoptosis-associated proteins (Bcl-2 and Bax) in PTC cells. A scratch wound assay was performed to measure the migration of PTC cells. A mouse xenograft test was performed to assess the effects of hsa_circ_0092355 in vivo. RIP and dual-luciferase reporter assays confirmed the association between miR-543 and hsa_circ_0092355 or PDE5A. Associations between miR-543, hsa_circ_0092355, and PDE5A were evaluated using Pearson's correlation coefficient. Upregulation of hsa_circ_0092355 was observed in PTC tissues. The hsa_circ_0092355 knockdown blocked the proliferation and migration of PTC cells and induced apoptosis. Moreover, hsa_circ_0092355 knockdown blocked PTC xenograft tumor growth in vivo. The miR-543 inhibitor could reverse the changes induced by hsa_circ_0092355 knockdown by hsa_circ_0092355 targeting miR-543. Furthermore, miR-543 suppresses PTC progression by downregulating PDE5A expression. Our findings suggest that the PTC tumor promoter hsa_circ_0092355 may promote carcinogenesis by controlling the miR-543/PDE5A pathway.

Evaluation of androgen receptor markers in erectile dysfunction.

BACKGROUND: Steroid hormones, such as testosterone, play a crucial role in modulating the development of male internal and external genitalia as well as secondary sex characteristics by binding to the androgen receptor. Once bound, androgen receptor operates as an inducible transcription factor, interacting with a multitude of co-regulators to initiate various downstream signaling pathways. The androgen saturation hypothesis posits that beyond a specific threshold, androgen receptor binding and functionality remain unaltered despite an increase in serum testosterone levels. OBJECTIVES: The objective of this study was to explore the expression of these proteins in penile tissue samples from men with severe erectile dysfunction to enhance our understanding of the influence of serum testosterone on androgen receptor function. MATERIALS AND METHODS: Patients undergoing surgical management for high-grade ED at our institution were invited to participate in the study. During inflatable penile prosthesis surgery, corpus cavernosum biopsy was obtained. Protein was extracted from each sample for western blot analysis which was probed with androgen receptor, heme oxygenase, inducible nitric oxide synthase, and phosphodiesterase type 5 antibodies with GAPDH for protein normalization. RESULTS: 12 men agreed to participate in this study. Serum testosterone levels were obtained from all participants on the morning of their surgery. The median testosterone level was 300.15 ng/dL. Our findings revealed a decrease in androgen receptor and inducible nitric oxide synthase expression at serum testosterone levels below 300 ng/dL (p = 0.022, 0.03). Similarly, hemeoxygenase and phosphodiesterase type 5 expression levels were significantly lower at serum T concentrations below 200 ng/dL (p = 0.017, 0.014). DISCUSSION AND CONCLUSION: These data showed a significant decrease in the expression of proteins downstream of the androgen receptor at lower serum T levels. This suggests a potential correlation between serum T concentration and androgen receptor signaling and supports a potential saturation value between 200 and 300 ng/dL.

Effects of acute phosphodiesterase type 5 inhibition on skeletal muscle interstitial PO2 during contractions and recovery.

The oxygen partial pressure within the interstitial space (PO2is; mmHg) provides the driving force for oxygen diffusion into the myocyte thereby supporting oxidative phosphorylation. We tested the hypothesis that potentiation of the nitric oxide pathway with sildenafil (phosphodiesterase type 5 inhibitor) would enhance PO2is during muscle metabolic transitions, thereby slowing PO2is on- and accelerating PO2is off-kinetics. The rat spinotrapezius muscle (n = 17) was exposed for PO2is measurements via phosphorescence quenching under control (CON), low-dose sildenafil (1 mg/kg i.a., SIL1) and high-dose sildenafil (7 mg/kg i.a., SIL7). Data were collected at rest and during submaximal twitch contractions (1 Hz, 4-6 V, 3 min) and recovery (3 min). Mean arterial blood pressure (MAP; mmHg) was reduced with both SIL1 (pre:132 ± 5; post:99 ± 5) and SIL7 (pre:111 ± 6; post:99 ± 4) (p < 0.05). SIL7 elevated resting PO2is (18.4 ± 1.1) relative to both CON (15.7 ± 0.7) and SIL1 (15.2 ± 0.7) (p < 0.05). In addition, SIL7 increased end-recovery PO2is (17.7 ± 1.6) compared to CON (12.8 ± 0.9) and SIL1 (13.4 ± 0.8) (p < 0.05). The overall PO2is response during recovery (i.e., area under the PO2is curve) was greater in SIL7 (4107 ± 444) compared to CON (3493 ± 222) and SIL1 (3114 ± 205 mmHg s) (p < 0.05). Contrary to our hypothesis, there was no impact of acute SIL (1 or 7 mg/kg) on the speed of the PO2is response during contractions or recovery (p > 0.05). However, sildenafil lowered MAP and improved skeletal muscle interstitial oxygenation in healthy rats. Specifically, SIL7 enhanced PO2is at rest and during recovery from submaximal muscle contractions. Potentiation of the nitric oxide pathway with sildenafil enhances microvascular blood-myocyte O2 transport and is expected to improve repeated bouts of contractile activity.

Drug repurposing and structure-based discovery of new PDE4 and PDE5 inhibitors.

Phosphodiesterase-4 (PDE4) and PDE5 responsible for the hydrolysis of intracellular cAMP and cGMP, respectively, are promising targets for therapeutic intervention in a wide variety of diseases. Here, we report the discovery of novel, drug-like PDE4 inhibitors by performing a high-throughput drug repurposing screening of 2560 approved drugs and drug candidates in clinical trial studies. It allowed us to identify eight potent PDE4 inhibitors with IC50 values ranging from 0.41 to 2.46 µM. Crystal structures of PDE4 in complex with four compounds, namely ethaverine hydrochloride (EH), benzbromarone (BBR), CX-4945, and CVT-313, were further solved to elucidate molecular mechanisms of action of these new inhibitors, providing a solid foundation for optimizing the inhibitors to improve their potency as well as selectivity. Unexpectedly, selectivity profiling of other PDE subfamilies followed by crystal structure determination revealed that CVT-313 was also a potent PDE5 inhibitor with a binding mode similar to that of tadalafil, a marketed PDE5 inhibitor, but distinctively different from the binding mode of CVT-313 with PDE4. Structure-guided modification of CVT-313 led to the discovery of a new inhibitor, compound 2, with significantly improved inhibitory activity as well as selectivity towards PDE5 over PDE4. Together, these results highlight the utility of the drug repurposing in combination with structure-based drug design in identifying novel inhibitors of PDE4 and PDE5, which provides a prime example for efficient discovery of drug-like hits towards a given target protein.

Coupling of conformational dynamics and inhibitor binding in the phosphodiesterase-5 family.

Phosphodiesterase-5 (PDE5) is responsible for regulating the concentration of the second messenger molecule cGMP by hydrolyzing it into 5'-GMP. PDE5 is implicated in erectile dysfunction and cardiovascular diseases. The substrate binding site in the catalytic domain of PDE5 is surrounded by several dynamic structural motifs (including the α14 helix, M-loop, and H-loop) that are known to switch between inactive and active conformational states via currently unresolved structural intermediates. We evaluated the conformational dynamics of these structural motifs in the apo state and upon binding of an allosteric inhibitor (evodiamine) or avanafil, a competitive inhibitor. We employed enhanced sampling-based replica exchange solute scaling (REST2) method, principal component analysis (PCA), time-lagged independent component analysis (tICA), molecular dynamics (MD) simulations, and well-tempered metadynamics simulations to probe the conformational changes in these structural motifs. Our results support a regulatory mechanism for PDE5, where the α14 helix alternates between an inward (lower activity) conformation and an outward (higher activity) conformation that is accompanied by the folding/unfolding of the α8' and α8″ helices of the H-loop. When the allosteric inhibitor evodiamine is bound to PDE5, the inward (inactive) state of the α14 helix is preferred, thus preventing substrate access to the catalytic site. In contrast, competitive inhibitors of PDE5 block catalysis by occupying the active site accompanied by stabilization of the outward conformation of the α14 helix. Defining the conformational dynamics underlying regulation of PDE5 activation will be helpful in rational design of next-generation small molecules modulators of PDE5 activity.

Optimizing metabolic stability of phosphodiesterase 5 inhibitors: Discovery of a potent N-(pyridin-3-ylmethyl)quinoline derivative targeting synaptic plasticity.

Phosphodiesterase 5 (PDE5) is a cyclic guanosine monophosphate-degrading enzyme involved in numerous biological pathways. Inhibitors of PDE5 are important therapeutics for the treatment of neurodegenerative diseases, including Alzheimer's disease (AD). We previously reported the first generation of quinoline-based PDE5 inhibitors for the treatment of AD. However, the short in vitro microsomal stability rendered them unsuitable drug candidates. Here we report a series of new quinoline-based PDE5 inhibitors. Among them, compound 4b, 8-cyclopropyl-3-(hydroxymethyl)-4-(((6-methoxypyridin-3-yl)methyl)amino)quinoline-6-carbonitrile, shows a PDE5 IC50 of 20 nM and improved in vitro microsomal stability (t1/2 = 44.6 min) as well as excellent efficacy in restoring long-term potentiation, a type of synaptic plasticity to underlie memory formation, in electrophysiology experiments with a mouse model of AD. These results provide an insight into the development of a new class of PDE5 inhibitors for the treatment of AD.

IncRNA XIST Stimulates Papillary Thyroid Cancer Development through the miR-330-3p/PDE5A Axis.

Long non-coding RNAs (lncRNAs) possess both tumor suppressive and oncogenic functions in papillary thyroid cancer (PTC). Among all the thyroid cancers, PTC is the most prevalent form. Herein, we aim to determine the regulatory mechanisms and functions of lncRNA XIST in the multiplication, invasion, and survival of PTC. Quantitative reverse transcription polymerase chain reaction and Western blot experiments were performed to determine the patterns of lncRNA XIST, miR-330-3p, and PDE5A expressions. The subcellular localization of XIST was determined through subcellular fractionation. Bioinformatics analyses were performed to determine miR-330-3p's relationships with XIST and PDE5A, which were further confirmed through luciferase reporter assays. Loss-of-function combined with Transwell, CCK-8, and caspase-3 activity experiments were performed to determine the mechanism of the XIST/miR-330-3p/PDE5A axis in regulating the malignancy of PTC cells. Xenograft tumor experiment was employed to study the influence of XIST on tumor development in vivo. The PTC cell lines and tissues manifested considerably high levels of lncRNA XIST expression. The XIST knockdown inhibited proliferation, blocked migration, and strengthened apoptosis among PTC cells. Moreover, its knockdown suppressed PTC tumor development in vivo. XIST repressed miR-330-3p to stimulate the malignant behaviors of PTC. Through the downregulation of PDE5A, miR-330-3p attenuated the capability of PTC cells to grow, migrate, and survive. lncRNA XIST promotes tumor development in PTC through the regulation of the miR-330-3p/PDE5A axis. The findings from this study provide new insights into the treatment of PTC.

Inhibition of phosphodiesterase 5A by tadalafil improves SIRT1 expression and activity in insulin-resistant podocytes.

A decrease in intracellular levels of 3',5'-cyclic guanosine monophosphate (cGMP) has been implicated in the progression of diabetic nephropathy. Hyperglycemia significantly inhibits cGMP-dependent pathway activity in the kidney, leading to glomerular damage and proteinuria. The enhancement of activity of this pathway that is associated with an elevation of cGMP levels may be achieved by inhibition of the cGMP specific phosphodiesterase 5A (PDE5A) using selective inhibitors, such as tadalafil. Hyperglycemia decreased the insulin responsiveness of podocytes and impaired podocyte function. These effects were associated with lower protein amounts and activity of the protein deacetylase sirtuin 1 (SIRT1) and a decrease in the phosphorylation of adenosine monophosphate-dependent protein kinase (AMPK). We found that PDE5A protein levels increased in hyperglycemia, and PDE5A downregulation improved the insulin responsiveness of podocytes with reestablished SIRT1 expression and activity. PDE5A inhibitors potentiate nitric oxide (NO)/cGMP signaling, and NO modulates the activity and expression of SIRT1. Therefore, we investigated the effects of tadalafil on SIRT1 and AMPK in the context of improving the insulin sensitivity in podocytes and podocyte function in hyperglycemia. Our study revealed that tadalafil restored SIRT1 expression and activity and activated AMPK by increasing its phosphorylation. Tadalafil also restored stimulating effect of insulin on glucose transport in podocytes with high glucose-induced insulin resistance. Additionally, tadalafil improved the function of podocytes that were exposed to high glucose concentrations. Our results display novel mechanisms involved in the pathogenesis of glomerulopathies in diabetes, which may contribute to the development of more effective treatment strategies for diabetic nephropathy.

Structural Characterization of Murine Phosphodiesterase 5 Isoforms and Involvement of Cysteine Residues in Supramolecular Assembly.

Phosphodiesterases (PDEs) are a superfamily of evolutionarily conserved cyclic nucleotide (cAMP/cGMP)-hydrolyzing enzymes, components of transduction pathways regulating crucial aspects of cell life. Within this family, the cGMP-dependent PDE5 is the major hydrolyzing enzyme in many mammalian tissues, where it regulates a number of cellular and tissular processes. Using Kluyveromyces lactis as a model organism, the murine PDE5A1, A2 and A3 isoforms were successfully expressed and studied, evidencing, for the first time, a distinct role of each isoform in the control, modulation and maintenance of the cellular redox metabolism. Moreover, we demonstrated that the short N-terminal peptide is responsible for the tetrameric assembly of MmPDE5A1 and for the mitochondrial localization of MmPDE5A2. We also analyzed MmPDE5A1, A2 and A3 using small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), structural mass spectrometry (MS) and polyacrylamide gel electrophoresis in their native conditions (native-PAGE) and in the presence of redox agents. These analyses pointed towards the role of a few specific cysteines in the isoforms' oligomeric assembly and the loss of enzymatic activity when modified.

Novel 9-Benzylaminoacridine Derivatives as Dual Inhibitors of Phosphodiesterase 5 and Topoisomerase II for the Treatment of Colon Cancer.

It has been shown that phosphodiesterase 5 (PDE5) inhibitors have anticancer effects in a variety of malignancies in both in vivo and in vitro experiments. The role of cGMP elevation in colorectal carcinoma (CRC) has been extensively studied. Additionally, DNA topoisomerase II (Topo II) inhibition is a well-established mechanism of action that mediates the effects of several approved anticancer drugs such as doxorubicin and mitoxantrone. Herein, we present 9-benzylaminoacridine derivatives as dual inhibitors of the PDE5 and Topo II enzymes. We synthesized 31 derivatives and evaluated them against PDE5, whereby 22 compounds showed micromolar or sub-micromolar inhibition. The anticancer activity of the compounds was evaluated with the NCI 60-cell line testing. Moreover, the effects of the compounds on HCT-116 colorectal carcinoma (CRC) were extensively studied, and potent compounds against HCT-116 cells were studied for their effects on Topo II, cell cycle progression, and apoptosis. In addition to exhibiting significant growth inhibition against HCT116 cells, compounds 11, 12, and 28 also exhibited the most superior Topo II inhibitory activity and low micromolar PDE5 inhibition and affected cell cycle progression. Knowing that compounds that combat cancer through multiple mechanisms are among the best candidates for effective therapy, we believe that the current class of compounds merits further optimization and investigation to unleash their full therapeutic potential.

Impaired Platelet Function and Thrombus Formation in PDE5A-Deficient Mice.

Intracellular cyclic GMP (cGMP) inhibits platelet function. Platelet cGMP levels are controlled by phosphodiesterase 5A (PDE5A)-mediated degradation. However, the exact role of PDE5A in platelet function and thrombus formation remains poorly understood. In this study, we characterized the role of PDE5A in platelet activation and function. Platelets were isolated from wild type or PDE5A-/- mice to measure platelet aggregation, activation, phosphatidylserine exposure (annexin-V binding), reactive oxygen species (ROS) generation, platelet spreading as well as clot retraction. Cytosolic calcium mobilization was measured using Fluo-4 AM by a microplate reader. Western blot was used to measure the phosphorylation of VASP, ERK1/2, p38, JNK, and AKT. FeCl3-induced arterial thrombosis and venous thrombosis were assessed to evaluate the in vivo hemostatic function and thrombus formation. Additionally, in vitro thrombus formation was assessed in a microfluidic whole-blood perfusion assay. PDE5A-deficient mice presented significantly prolonged tail bleeding time and delayed arterial and venous thrombus formation. PDE5A deficiency significantly inhibited platelet aggregation, ATP release, P-selectin expression, and integrin aIIbb3 activation. In addition, an impaired spreading on collagen or fibrinogen and clot retraction was observed in PDE5A-deficient platelets. Moreover, PDE5A deficiency reduced phosphatidylserine exposure, calcium mobilization, ROS production, and increased intracellular cGMP level along with elevated VASP phosphorylation and reduced phosphorylation of ERK1/2, p38, JNK, and AKT. In conclusion, PDE5A modulates platelet activation and function and thrombus formation, indicating that therapeutically targeting it might be beneficial for the treatment of thrombotic diseases.

Effects of tadalafil on skeletal muscle tissue: exploring interactions and novel mechanisms of action.

Beside its mechanical roles in controlling posture and locomotion, skeletal muscle system, the largest insulin and steroid hormones target tissue, plays a key role in influencing thermoregulation, secondary sexual characteristics, hormones metabolism, and glucose uptake and storage, as well as energetic metabolism. Indeed, in addition to insulin, several hormones influence the skeletal muscle metabolism/function and/or are influenced by skeletal muscles activity (i.e., physical exercise). Particularly, steroid hormones play a key role in modulating many biological processes in muscles, essential for overall muscle's function and homeostasis, both at rest and during all physical activities (i.e., physical exercise, muscular work). Phosphodiesterase type 5 (PDE5) is the enzyme engaged to hydrolyze cyclic guanosine monophosphate (cGMP) in inactive 5'-GMP form. Therefore, through the inhibition of this enzyme, the intracellular level of cGMP increases, and the cGMP-related cellular responses are prolonged. Different drugs inhibiting PDE5 (PDE5i) exist, and the commercially available PDE5i are sildenafil, vardenafil, tadalafil, and avanafil. The PDE5i tadalafil may influence cellular physiology and endocrine-metabolic pathways in skeletal muscles and exerts its functions both by activating the cell signaling linked to the insulin-related metabolic pathways and modulating the endocrine responses, protein catabolism and hormone-related anabolism/catabolism during and after physical exercise-related stress. Based on recent in-vivo and in-vitro findings, in this narrative review the aim was to summarize the available evidence describing the interactions between the PDE5i tadalafil and steroid hormones in skeletal muscle tissue and physical exercise adaptation, focusing our interest on their possible synergistic or competitive action(s) on muscle metabolism and function.

Cellular Redox Metabolism Is Modulated by the Distinct Localization of Cyclic Nucleotide Phosphodiesterase 5A Isoforms.

3'-5' cyclic nucleotide phosphodiesterases (PDEs) are a family of evolutionarily conserved cAMP and/or cGMP hydrolyzing enzymes, components of transduction pathways regulating crucial aspects of cell life. Among them, cGMP-specific PDE5-being a regulator of vascular smooth muscle contraction-is the molecular target of several drugs used to treat erectile dysfunction and pulmonary hypertension. Production of full-length murine PDE5A isoforms in the milk-yeast Kluyveromyces lactis showed that the quaternary assembly of MmPDE5A1 is a mixture of dimers and tetramers, while MmPDE5A2 and MmPDE5A3 only assembled as dimers. We showed that the N-terminal peptide is responsible for the tetramer assembly of MmPDE5A1, while that of the MmPDE5A2 is responsible for its mitochondrial localization. Overexpression of the three isoforms alters at different levels the cAMP/cGMP equilibrium as well as the NAD(P)+/NAD(P)H balance and induces a metabolic switch from oxidative to fermentative. In particular, the mitochondrial localization of MmPDE5A2 unveiled the existence of a cAMP-cGMP signaling cascade in this organelle, for which we propose a metabolic model that could explain the role of PDE5 in some cardiomyopathies and some of the side effects of its inhibitors.

The NO/cGMP/PKG pathway in platelets: The therapeutic potential of PDE5 inhibitors in platelet disorders.

Platelets are the "guardians" of the blood circulatory system. At sites of vessel injury, they ensure hemostasis and promote immunity and vessel repair. However, their uncontrolled activation is one of the main drivers of thrombosis. To keep circulating platelets in a quiescent state, the endothelium releases platelet antagonists including nitric oxide (NO) that acts by stimulating the intracellular receptor guanylyl cyclase (GC). The latter produces the second messenger cyclic guanosine-3',5'-monophosphate (cGMP) that inhibits platelet activation by stimulating protein kinase G, which phosphorylates hundreds of intracellular targets. Intracellular cGMP pools are tightly regulated by a fine balance between GC and phosphodiesterases (PDEs) that are responsible for the hydrolysis of cyclic nucleotides. Phosphodiesterase type 5 (PDE5) is a cGMP-specific PDE, broadly expressed in most tissues in humans and rodents. In clinical practice, PDE5 inhibitors (PDE5i) are used as first-line therapy for erectile dysfunction, pulmonary artery hypertension, and lower urinary tract symptoms. However, several studies have shown that PDE5i may ameliorate the outcome of various other conditions, like heart failure and stroke. Interestingly, NO donors and cGMP analogs increase the capacity of anti-platelet drugs targeting the purinergic receptor type Y, subtype 12 (P2Y12) receptor to block platelet aggregation, and preclinical studies have shown that PDE5i inhibits platelet functions. This review summarizes the molecular mechanisms underlying the effect of PDE5i on platelet activation and aggregation focusing on the therapeutic potential of PDE5i in platelet disorders, and the outcomes of a combined therapy with PDE5i and NO donors to inhibit platelet activation.

Tadalafil and Steroid Hormones Interactions in Adipose, Bone and Prostate Tissues: Focus on Translational Perspectives.

Tadalafil is a selective phosphodiesterase type-5 (PDE5) inhibitor that is approved for the treatment of men with erectile dysfunction (ED) and/or benign prostate hyperplasia (BPH) -associated symptoms. Besides its classical actions on PDE5 within the genitourinary tract, where the specific enzyme expression is maximal, it may exert different systemic effects. This is mainly due to the pleiotropic distribution of PDE5 enzyme throughout the human (and animal) body, where it can exert protective effects in different clinical conditions. Recently, it has been demonstrated that tadalafil may display novel actions on androgen receptor (AR) expression and activity and cytochrome P19a1 (Cyp19a1) and estrogen receptor ß (ERß) expression in different in vitro systems, such as adipose, bone and prostate cancer cells, where it can act as a selective modulator of steroid hormone production. This may determine novel potential mechanism(s) of control in pathophysiologic pathways. In this review, we summarize basic research and translational results applicable to the use of tadalafil in the treatment of obesity, bone loss and prostate cancer.

Main active components of Si-Miao-Yong-An decoction (SMYAD) attenuate autophagy and apoptosis via the PDE5A-AKT and TLR4-NOX4 pathways in isoproterenol (ISO)-induced heart failure models.

Heart failure (HF), the main cause of death in patients with many cardiovascular diseases, has been reported to be closely related to the complicated pathogenesis of autophagy, apoptosis, and inflammation. Notably, Si-Miao-Yong-An decoction (SMYAD) is a traditional Chinese medicine (TCM) used to treat cardiovascular disease; however, the main active components and their relevant mechanisms remain to be discovered. Based on our previous ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q/TOF-MS) results, we identified angoriside C (AC) and 3,5-dicaffeoylquinic acid (3,5-DiCQA) as the main active components of SMYAD. In vivo results showed that AC and 3,5-DiCQA effectively improved cardiac function, reduced the fibrotic area, and alleviated isoproterenol (ISO)-induced myocarditis in rats. Moreover, AC and 3,5-DiCQA inhibited ISO-induced autophagic cell death by inhibiting the PDE5A/AKT/mTOR/ULK1 pathway and inhibited ISO-induced apoptosis by inhibiting the TLR4/NOX4/BAX pathway. In addition, the autophagy inhibitor 3-MA was shown to reduce ISO-induced apoptosis, indicating that ISO-induced autophagic cell death leads to excess apoptosis. Taken together, the main active components AC and 3,5-DiCQA of SMYAD inhibit the excessive autophagic cell death and apoptosis induced by ISO by inhibiting the PDE5A-AKT and TLR4-NOX4 pathways, thereby reducing myocardial inflammation and improving heart function to alleviate and treat a rat ISO-induced heart failure model and cell heart failure models. More importantly, the main active components of SMYAD will provide new insights into a promising strategy that will promote the discovery of more main active components of SMYAD for therapeutic purposes in the future.

Effects of phosphodiesterase 5 inhibition on cardiovascular function in resistant hypertension: A systematic review.

Approximately 12-18% of hypertensive patients are diagnosed with resistant hypertension (RH). The risk of having worse cardiovascular outcomes is twice higher in those patients. The low effectiveness of conventional antihypertensive drugs in RH emphasizes the need to evaluate complementary drug therapies to achieve blood pressure (BP) control. Previous studies have demonstrated that phosphodiesterase 5 (PDE-5) inhibitors improve hemodynamics and reduce BP on essential hypertension. So, the authors aimed to summarize current clinical trials-based evidence published concerning the use of PDE-5 inhibitors on BP, cardiovascular function, and hemodynamics of patients with RH. We searched MEDLINE, EMBASE, LILACS, ClinicalTrials.gov, and WHO International Clinical Trials Registry databases on May 15th, 2020 using pre-defined search terms. Two independent reviewers assessed and extracted data from clinical trials that evaluated the effect of PDE-5 inhibitors on BP. We have included five articles in this systematic review. Four of them developed a single-day protocol, while one has developed a 14-day study. The main findings indicate that PDE-5 inhibitors ameliorate BP, vascular hemodynamics, and diastolic function parameters. Some data demonstrated improvement of endothelial function, but it was not a consensus. The side effects seemed to be limited and well-tolerated. In brief, our systematic review highlights the potential of PDE-5 inhibitors as a therapeutic alternative in addition to the multiple-drug regime for RH. Larger studies are still needed to determine whether the beneficial effects of PDE-5 inhibitors on RH would be maintained with chronic administration.

Phosphodiesterase 5a Signalling in Skeletal Muscle Pathophysiology.

Phosphodiesterase 5A (PDE5A) is involved in cGMP hydrolysis, regulating many physiological processes. Increased activity of PDE5A has been found in several pathological conditions, and the pharmacological inhibition of PDE5 has been demonstrated to have several therapeutic applications. We have identified the presence of three different Pde5a isoforms in cardiomyocytes, and we have found that the expression of specific Pde5a isoforms may have a causal role in the onset of pathological responses in these cells. In our previous study, we demonstrated that PDE5A inhibition could ameliorate muscular dystrophy by acting at different levels, as assessed by the altered genomic response of muscular cells following treatment with the PDE5A inhibitor tadalafil. Thus, considering the importance of PDE5A in various pathophysiological conditions, we further investigated the regulation of this enzyme. Here, we analysed the expression of Pde5a isoforms in the pathophysiology of skeletal muscle. We found that skeletal muscle tissues and myogenic cells express Pde5a1 and Pde5a2 isoforms, and we observed an increased expression of Pde5a1 in damaged skeletal muscles, while Pde5a2 levels remained unchanged. We also cloned and characterized the promoters that control the transcription of Pde5a isoforms, investigating which of the transcription factors predicted by bioinformatics analysis could be involved in their modulation. In conclusion, we found an overexpression of Pde5a1 in compromised muscle and identified an involvement of MyoD and Runx1 in Pde5a1 transcriptional activity.