Allicin Could Potentially Alleviate Oral Cancer Pain by Inhibiting "Pain Mediators" TNF-alpha, IL-8, and Endothelin.

To evaluate the effects of allicin on mediators of pain secreted by oral cancer cells in vitro, single-cell suspensions were prepared by enzymatic method from oral squamous cell carcinoma (OSCC). Cancer stem cells were isolated by the CD133+ selection method with magnetic cell sorting. Stemness markers were checked in both cancer cells and cancer stem cells by RT-PCR. Comparative analysis of pain mediators TNF-alpha, IL-8, and endothelin at both RNA and protein levels for normal epithelial cells, cancer cells, and cancer stem cells was carried out with and without allicin treatment. CD133 and CD44 expression levels were checked in cancer cells and cancer stem cells flow cytometrically. Allicin inhibited both gene and protein expression of TNF-alpha, IL-8, and endothelin in both cancer cells and cancer stem cells. Allicin is more likely to be a promising treatment in alleviating the levels of pain and inflammation in OSCCs.

Inhibition of Endothelin system during the postnatal nephrogenic period in the rat. Its relationship with hypertension and renal disease in adulthood.

The aim of this work was to study the effect of a high sodium (HS) diet on blood pressure and renal function in male adult rats that have been treated with a dual Endothelin receptor antagonist (ERA) during their early postnatal period (day 1 to 20 of life). Male Sprague-Dawley rats were divided in four groups: CNS: control rats with normosodic diet; ERANS: ERA-treated rats with normosodic diet; CHS: control rats with high sodium diet; ERAHS: ERA-treated rats with HS diet. Systolic blood pressure (SBP) was recorded before and after the diet and 24-hour metabolic cage studies were performed. AQP2 and α-ENac expressions were measured by western blot and real time PCR in the renal medulla. Vasopressin (AVP) pathway was evaluated by measuring V2 receptor and adenylyl cyclase 6 (AC6) expression and cAMP production in the renal medulla. Pre-pro ET-1mRNA was also evaluated in the renal medulla. Only rats that had been treated with an ERA during their postnatal period increased their SBP after consumption of a HS diet, showing an impaired capacity to excrete sodium and water, i.e. developing salt sensitivity. This salt sensitivity would be mediated by an increase in renomedullary expression and activity of AQP2 and α-ENaC as a consequence of increased AC6 expression and cAMP production and/or a decreased ET-1 production in the renal medulla. The knowledge of the molecular mechanisms underlying the perinatal programming of salt sensitive hypertension will allow the development of reprogramming strategies in order to avoid this pathology.

New drugs and emerging therapeutic targets in the endothelin signaling pathway and prospects for personalized precision medicine.

During the last thirty years since the discovery of endothelin-1, the therapeutic strategy that has evolved in the clinic, mainly in the treatment of pulmonary arterial hypertension, is to block the action of the peptide either at the ET(A) subtype or both receptors using orally active small molecule antagonists. Recently, there has been a rapid expansion in research targeting ET receptors using chemical entities other than small molecules, particularly monoclonal antibody antagonists and selective peptide agonists and antagonists. While usually sacrificing oral bio-availability, these compounds have other therapeutic advantages with the potential to considerably expand drug targets in the endothelin pathway and extend treatment to other pathophysiological conditions. Where the small molecule approach has been retained, a novel strategy to combine two vasoconstrictor targets, the angiotensin AT(1) receptor as well as the ET(A) receptor in the dual antagonist sparsentan has been developed. A second emerging strategy is to combine drugs that have two different targets, the ET(A) antagonist ambrisentan with the phosphodiesterase inhibitor tadalafil, to improve the treatment of pulmonary arterial hypertension. The solving of the crystal structure of the ET(B) receptor has the potential to identify allosteric binding sites for novel ligands. A further key advance is the experimental validation of a single nucleotide polymorphism that has genome wide significance in five vascular diseases and that significantly increases the amount of big endothelin-1 precursor in the plasma. This observation provides a rationale for testing this single nucleotide polymorphism to stratify patients for allocation to treatment with endothelin agents and highlights the potential to use personalized precision medicine in the endothelin field.

Endothelin and diabetic complications: a brain-centric view.

The global epidemic of diabetes is of significant concern. Diabetes associated vascular disease signifies the principal cause of morbidity and mortality in diabetic patients. It is also the most rapidly increasing risk factor for cognitive impairment, a silent disease that causes loss of creativity, productivity, and quality of life. Small vessel disease in the cerebral vasculature plays a major role in the pathogenesis of cognitive impairment in diabetes. Endothelin system, including endothelin-1 (ET-1) and the receptors (ET(A) and ET(B)), is a likely candidate that may be involved in many aspects of the diabetes cerebrovascular disease. In this review, we took a brain-centric approach and discussed the role of the ET system in cerebrovascular and cognitive dysfunction in diabetes.

Bone-targeted therapies to reduce skeletal morbidity in prostate cancer.

Bone metastases are the main driver of morbidity and mortality in advanced prostate cancer. Targeting the bone microenvironment, a key player in the pathogenesis of bone metastasis, has become one of the mainstays of therapy in men with advanced prostate cancer. This review will evaluate the data supporting the use of bone-targeted therapy, including (1) bisphosphonates such as zoledronic acid, which directly target osteoclasts, (2) denosumab, a receptor activator of nuclear factor-kappa B (RANK) ligand inhibitor, which targets a key component of bone stromal interaction, and (3) radium-223, an alpha-emitting calcium mimetic, which hones to the metabolically active areas of osteoblastic metastasis and induces double-strand breaks in the DNA. Denosumab has shown enhanced delay in skeletal-related events compared to zoledronic acid in patients with metastatic castration-resistant prostate cancer (mCRPC). Data are mixed with regard to pain control as a primary measure of efficacy. New data call into question dosing frequency, with quarterly dosing strategy potentially achieving similar effect compared to monthly dosing for zoledronic acid. In the case of radium-223, there are data for both pain palliation and improved overall survival in mCRPC. Further studies are needed to optimize timing and combination strategies for bone-targeted therapies. Ongoing studies will explore the impact of combining bone-targeted therapy with investigational therapeutic agents such as immunotherapy, for advanced prostate cancer. Future studies should strive to develop biomarkers of response, in order to improve efficacy and cost-effectiveness of these agents.

Bone-targeted therapies to reduce skeletal morbidity in prostate cancer / 亚洲男科学杂志(英文版)

Bone metastases are the main driver of morbidity and mortality in advanced prostate cancer. Targeting the bone microenvironment, a key player in the pathogenesis of bone metastasis, has become one of the mainstays of therapy in men with advanced prostate cancer. This review will evaluate the data supporting the use of bone-targeted therapy, including (1) bisphosphonates such as zoledronic acid, which directly target osteoclasts, (2) denosumab, a receptor activator of nuclear factor-kappa B (RANK) ligand inhibitor, which targets a key component of bone stromal interaction, and (3) radium-223, an alpha-emitting calcium mimetic, which hones to the metabolically active areas of osteoblastic metastasis and induces double-strand breaks in the DNA. Denosumab has shown enhanced delay in skeletal-related events compared to zoledronic acid in patients with metastatic castration-resistant prostate cancer (mCRPC). Data are mixed with regard to pain control as a primary measure of efficacy. New data call into question dosing frequency, with quarterly dosing strategy potentially achieving similar effect compared to monthly dosing for zoledronic acid. In the case of radium-223, there are data for both pain palliation and improved overall survival in mCRPC. Further studies are needed to optimize timing and combination strategies for bone-targeted therapies. Ongoing studies will explore the impact of combining bone-targeted therapy with investigational therapeutic agents such as immunotherapy, for advanced prostate cancer. Future studies should strive to develop biomarkers of response, in order to improve efficacy and cost-effectiveness of these agents.

Comparison of endothelin and nitric oxide synthase blockers on hemorheological parameters in endotoxemic rats.

BACKGROUND/AIM: Septic shock is an important health problem that vastly alters cardiovascular and hemodynamic status. Increased production of nitric oxide (NO) and endothelin is a counterpart of this endotoxemic state. This study was conducted to test the hypothesis that nonselective NO synthesis blocker (L-NAME), inducible NO synthesis blocker (L-canavanine), or endothelin receptor antagonist (bosentan) will reverse the effects of sepsis on hemorheological parameters. MATERIALS AND METHODS: Forty-eight male Sprague-Dawley rats were used in 8 groups: saline (control), endotoxin, bosentan, L-NAME, L-canavanine, endotoxin + bosentan, endotoxin + L-NAME, and endotoxin + L-canavanine. Blood was withdrawn at the 4th hour of endotoxemic state. Erythrocyte deformability and erythrocyte aggregation were determined by laser-assisted optical rotational cell analyzer at 37 °C. Plasma viscosity (mPa.s) was measured by a cone-plate viscometer with 0.5 mL of plasma. RESULTS: Endotoxin administration significantly increased aggregation half-time and lowered erythrocyte aggregation amplitude and aggregation index compared to the control, indicating a slower and weaker aggregation pattern. L-NAME and L-canavanine alleviated the effects of endotoxin on erythrocyte aggregation without altering the values in the control animals. However, bosentan did not perform such a restoration. CONCLUSION: This finding suggests that these restoration effects of the blockers occur via their modulation of nitric oxide synthesis rather than through the endothelin pathway.

Dexamethasone Downregulates Endothelin Receptors and Reduces Endothelin-Induced Production of Matrix Metalloproteinases in Cultured Rat Astrocytes.

In brain disorders, astrocytes change phenotype to reactive astrocytes and are involved in the induction of neuroinflammation and brain edema. The administration of glucocorticoids (GCs), such as dexamethasone (Dex), reduces astrocytic activation, but the mechanisms underlying this inhibitory action are not well understood. Endothelins (ETs) promote astrocytic activation. Therefore, the effects of Dex on ET receptor expressions were examined in cultured rat astrocytes. Treatment with 300 nM Dex for 6-48 hours reduced the mRNA expression of astrocytic ETA and ETB receptors to 30-40% of nontreated cells. Levels of ETA and ETB receptor proteins became about 50% of nontreated cells after Dex treatment. Astrocytic ETA and ETB receptor mRNAs were decreased by 300 nM hydrocortisone. The effects of Dex and hydrocortisone on astrocytic ET receptors were abolished in the presence of mifepristone, a GC receptor antagonist. Although Dex did not decrease the basal levels of matrix metalloproteinase (MMP) 3 and MMP9 mRNAs, pretreatment with Dex reduced ET-induced increases in MMP mRNAs. The effects of ET-1 on the release of MMP3 and MMP9 proteins were attenuated by pretreatment with Dex. ET-1 stimulated the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) in cultured astrocytes. Pretreatment with Dex reduced the ET-induced increases in ERK1/2 phosphorylation. In contrast, pretreatment with Dex did not affect MMP production or ERK1/2 phosphorylation induced by phorbol myristate acetate, a protein kinase C activator. These results indicate that Dex downregulates astrocytic ET receptors and reduces ET-induced MMP production.

Endothelin contributes to the blood pressure rise triggered by hypoxia in severe obstructive sleep apnea.

BACKGROUND: Obstructive sleep apnea (OSA) is strongly correlated with an increased risk of systemic hypertension. However, the link between systemic hypertension and nocturnal apneas remains incompletely understood. Animal studies suggest an implication of the endothelin system. The aim of the present study is to determine if endogenous endothelin plays a role in the increase in blood pressure observed during hypoxic episodes in OSA patients, in addition to peripheral chemoreflex and neural sympathetic activation. METHODS: We assessed the effects of the nonspecific endothelin antagonist bosentan (500 mg; Tracleer; Actelion; Basel, Switzerland) on ventilation, hemodynamics, and muscle sympathetic nerve activity (MSNA) during normoxia and isocapnic hypoxia using a randomized, crossover, double-blinded, placebo-controlled study design, and in 13 severely untreated sleep apneic patients (age 50 ±â€Š9 years, apnea-hypopnea index 35 ±â€Š21/h). RESULTS: Hypoxia increased blood pressure, MSNA, and minute ventilation as oxygen saturation decreased. Bosentan suppressed completely the increase in SBP during a 5-min hypoxic challenge (143 ±â€Š5 mmHg during hypoxia vs. 133 ±â€Š5 mmHg during normoxia with placebo and 127 ±â€Š3 mmHg during hypoxia vs. 125 ±â€Š3 mmHg during normoxia under bosentan, P = 0.023). DBP as well as the rise in MSNA and ventilation during isocapnic hypoxia did not differ between bosentan and placebo. CONCLUSION: Endothelin contributes to the rise in SBP in response to acute hypoxia in patients with severely untreated OSA. This was not due to lower chemoreflex activation with bosentan.

Diabetic nephropathy: where are we on the journey from pathophysiology to treatment?

Diabetic nephropathy affects 30-40% of people with diabetes, and is the leading cause of end-stage kidney disease. The current treatment paradigm relies on early detection, glycaemic control and tight blood pressure management with preferential use of renin-angiotensin system blockade. This strategy has transformed outcomes in diabetic kidney disease over the last 20 years. Over the last two decades we have also witnessed significant advances in the understanding of the pathophysiology of diabetic nephropathy; however, despite this new knowledge, we have yet to develop new treatments of proven efficacy. Whilst a continued emphasis on preclinical and clinical research is clearly needed, clinicians treating people with diabetes should not forget that, in the short term, the greatest gains are likely to be realised by more consistent deployment of existing therapies.

In Vitro Evaluation of Carbachol and Endothelin on Contractility of Colonic Smooth Muscle in Hirschsprung's Disease.

Background: The hypomotility of colon observed in Hirschsprung's disease (HD) has been attributed to congenital aganglionosis only. So far, it is not clear whether the contractility of colonic smooth muscle in this condition is altered or not. Therefore, the present study attempted to understand the contractile status of colonic segments of HD patients by examining carbachol and endothelin (ET-1) evoked colonic smooth muscle contractions in vitro . Methods: Contractile responses were recorded from strips of colonic segments obtained from HD patients, using organ bath preparations. Cholinergic agonist carbachol and ET-1 along with their antagonists were used to evoke contractile responses. Thereafter, the samples were histopathologically confirmed for HD. Results: Colonic strips of HD did not show any spontaneous contractions but responded to carbachol and ET-1 to a lesser extent. In HD, response of carbachol was blocked by atropine and hexamethonium by nearly 73% and 50% respectively. ET-1 induced contractile responses were blocked by ET-A and ET-B antagonist up to 40%, signifying the possible role of ET-A and ET-B receptors in HD colon contractility. Conclusion: As evidenced by lack of spontaneous contractions and impaired carbachol and ET-1-induced contractile responses, it is concluded that, in addition to aganglionosis, decreased contractility of colonic smooth muscle may contribute to hypomotility observed in patients with HD.

Marine and soil derived natural products: a new source of novel cardiovascular protective agents targeting the endothelin system.

Inhibition of the endothelin system is a recognized therapeutic approach for treating complex cardiovascular diseases. The search for natural inhibitors of the endothelin system has focused mainly on land, with recent, emerging data suggesting the underestimated potential of marine microorganisms for producing leads with cardioprotective potential. The present work reviews natural products identified as inhibitors of the endothelin system, their origin, their mechanism of action, and their ecological significance.

Clinical pharmacology of endothelin receptor antagonists used in the treatment of pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a devastating life-threatening disorder characterized by elevated pulmonary vascular resistance leading to elevated pulmonary arterial pressures, right ventricular failure, and ultimately death. Vascular endothelial cells mainly produce and secrete endothelin (ET-1) in vessels that lead to a potent and long-lasting vasoconstrictive effect in pulmonary arterial smooth muscle cells. Along with its strong vasoconstrictive action, ET-1 can promote smooth muscle cell proliferation. Thus, ET-1 blockers have attracted attention as an antihypertensive drug, and the ET-1 signaling system has paved a new therapeutic avenue for the treatment of PAH. We outline the current understanding of not only the pathogenic role played by ET-1 signaling systems in the pathogenesis of PH but also the clinical pharmacology of endothelin receptor antagonists (ERA) used in the treatment of PAH.

Combined endothelin a blockade and chlorthalidone treatment in a rat model of metabolic syndrome.

Experiments determined whether the combination of endothelin A (ETA) receptor antagonist [ABT-627, atrasentan; (2R,3R,4S)-4-(1,3-benzodioxol-5-yl)-1-[2-(dibutylamino)-2-oxoethyl]-2-(4-methoxyphenyl)pyrrolidine-3-carboxylic acid] and a thiazide diuretic (chlorthalidone) would be more effective at lowering blood pressure and reducing renal injury in a rodent model of metabolic syndrome compared with either treatment alone. Male Dahl salt-sensitive rats were fed a high-fat (36% fat), high-salt (4% NaCl) diet for 4 weeks. Separate groups of rats were then treated with vehicle (control), ABT-627 (ABT; 5 mg/kg per day, in drinking water), chlorthalidone (CLTD; 5 mg/kg per day, in drinking water), or both ABT plus CLTD. Mean arterial pressure (MAP) was recorded continuously by telemetry. After 4 weeks, both ABT and CLTD severely attenuated the development of hypertension, whereas the combination further reduced MAP compared with ABT alone. All treatments prevented proteinuria. CLTD and ABT plus CLTD significantly reduced nephrin (a podocyte injury marker) and kidney injury molecule-1 (a tubulointerstitial injury marker) excretion. ABT, with or without CLTD, significantly reduced plasma 8-oxo-2'-deoxyguanosine, a measure of DNA oxidation, whereas CLTD alone had no effect. All treatments suppressed the number of ED1(+) cells (macrophages) in the kidney. Plasma tumor necrosis factor receptors 1 and 2 were reduced only in the combined ABT and CLTD group. These results suggest that ABT and CLTD have antihypertensive and renal-protective effects in a model of metabolic syndrome that are maximally effective when both drugs are administered together. The findings support the hypothesis that combined ETA antagonist and diuretic treatment may provide therapeutic benefit for individuals with metabolic syndrome consuming a Western diet.

Endothelin and endothelin antagonists in chronic kidney disease.

The incidence and prevalence of chronic kidney disease (CKD), with diabetes and hypertension accounting for the majority of cases, is on the rise, with up to 160 million individuals worldwide predicted to be affected by 2020. Given that current treatment options, primarily targeted at the renin-angiotensin system, only modestly slow down progression to end-stage renal disease, the urgent need for additional effective therapeutics is evident. Endothelin-1 (ET-1), largely through activation of endothelin A receptors, has been strongly implicated in renal cell injury, proteinuria, inflammation, and fibrosis leading to CKD. Endothelin receptor antagonists (ERAs) have been demonstrated to ameliorate or even reverse renal injury and/or fibrosis in experimental models of CKD, whereas clinical trials indicate a substantial antiproteinuric effect of ERAs in diabetic and nondiabetic CKD patients even on top of maximal renin-angiotensin system blockade. This review summarizes the role of ET in CKD pathogenesis and discusses the potential therapeutic benefit of targeting the ET system in CKD, with attention to the risks and benefits of such an approach.

Novel therapies for diabetic kidney disease.

The number of people diagnosed with diabetes is rising throughout the world, which in turn drives upward the global frequency of diabetic kidney disease (DKD). Individuals with DKD are at an increased risk for premature death, cardiovascular disease, and other severe illnesses that result in frequent hospitalizations and increased health-care utilization. Current treatments concentrate on controlling hyperglycemia and hypertension with the specific use of renin-angiotensin system inhibitors. Although such measures reduce the risk of progressive kidney disease, DKD remains the leading cause of ESRD and the major risk amplifier for death in this population. Therefore, novel therapeutic approaches are urgently needed. Ideas for novel targets for therapy are founded on recent advances in understanding DKD mechanisms that are based on experimental models and human observations. The purpose of this review is to describe the epidemiology and present knowledge of DKD pathophysiology as the basis for novel therapies including inhibitors of Janus kinases (JAK), protein kinase C, fibrosis, advanced glycation end products treatments, and endothelin.

Endothelin antagonism for patients with chronic kidney disease: still a hope for the future.

Endothelin is tightly involved in the regulation of vascular and renal function in health and in disease. In a variety of animal models of kidney disease, endothelin promotes renal injury through effects on inflammation and fibrosis. Furthermore, experimental data strongly suggest that blocking the actions of endothelin should be beneficial in patients with chronic kidney disease. However, despite encouraging pre-clinical and clinical evidence, endothelin antagonists are not yet an established treatment option in patients with chronic kidney disease. This article reviews key physiological and pathophysiological aspects of the endothelin system in the vasculature and the kidney, as well as results of pre-clinical and clinical studies on the use of endothelin antagonists in chronic kidney disease. We will also provide an outlook on the future of endothelin antagonism in this area, and issues to be resolved before endothelin antagonists are to become a reality for patients with chronic kidney disease.

Pulmonary vasoconstrictor influence of endothelin in exercising swine depends critically on phosphodiesterase 5 activity.

Both phosphodiesterase 5 (PDE5) inhibition and endothelin (ET) receptor blockade have been shown to induce pulmonary vasodilation. However, little is known about the effect of combined blockade of these two vasoconstrictor pathways. Since nitric oxide (NO) exerts its pulmonary vasodilator influence via production of cyclic guanosine monophosphate (cGMP) as well as through inhibition of ET, we hypothesized that interaction between the respective signaling pathways precludes an additive vasodilator effect. We tested this hypothesis in chronically instrumented swine exercising on a treadmill by comparing the vasodilator effect of the PDE5 inhibitor EMD360527, the ETA/ETB antagonist tezosentan, and combined EMD360527 and tezosentan. In the systemic circulation, vasodilation by tezosentan and EMD360527 was additive, both at rest and during exercise, resulting in a 17 ± 2% drop in blood pressure. In the pulmonary circulation, both EMD360527 and tezosentan produced vasodilation. However, tezosentan produced no additional pulmonary vasodilation in the presence of EMD360527, either at rest or during exercise. Moreover, in isolated preconstricted porcine pulmonary small arteries (∼300 µm) EMD360527 (1 nM-10 µM) induced dose-dependent vasodilation, whereas tezosentan (1 nM-10 µM) failed to elicit vasodilation irrespective of the presence of EMD360527. However, both PDE5 inhibition and 8Br-cGMP, but not 8Br-cAMP, blunted pulmonary small artery contraction to ET and its precursor Big ET in vitro. In conclusion, in healthy swine, either at rest or during exercise, PDE5 inhibition and the associated increase in cGMP produce pulmonary vasodilation that is mediated in part through inhibition of the ET pathway, thereby precluding an additional vasodilator effect of ETA/ETB receptor blockade in the presence of PDE5 inhibition.

The endothelin axis in head and neck cancer: a promising therapeutic opportunity?

The incidence of head and neck cancer, predominantly consisting of squamous cell carcinomas (HNSCCs), is continuing to rise worldwide. Invasive HNSCC carries a poor prognosis, and the detrimental sequelae of surgical resection motivate identification of novel modes of therapeutic intervention. The endothelin (ET) axis consists of ET-1, 2 and 3, which are generated by endothelin-converting enzyme (ECE) and engage with the receptors ETA R and ETB R. The ET axis plays a role in the development and progression of various human malignancies. ET axis components have been found to be overexpressed in HNSCC; ET-1 antagonism and inhibition of ECE may therefore represent viable therapeutic opportunities. ET-1 can promote HNSCC progression via stromal-epithelial interactions, suggesting that the stroma may also hold potential for therapies targeting components of the ET axis. The ET axis may also offer components that can be used as biomarkers - for screening, diagnosis, monitoring disease recurrence and prognostic risk stratification of patients - and targets for localised analgesia offering less systemic side effects. This review summarises the current knowledge and potential for clinical opportunities related to the ET axis.