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Nature Metabolism Nov 2019Senescence is a cellular stress response that results in the stable arrest of old, damaged or preneoplastic cells. Oncogene-induced senescence is tumor suppressive but...
Senescence is a cellular stress response that results in the stable arrest of old, damaged or preneoplastic cells. Oncogene-induced senescence is tumor suppressive but can also exacerbate tumorigenesis through the secretion of pro-inflammatory factors from senescent cells. Drugs that selectively kill senescent cells, termed senolytics, have proved beneficial in animal models of many age-associated diseases. Here, we show that the cardiac glycoside, ouabain, is a senolytic agent with broad activity. Senescent cells are sensitized to ouabain-induced apoptosis, a process mediated in part by induction of the pro-apoptotic Bcl2-family protein NOXA. We show that cardiac glycosides synergize with anti-cancer drugs to kill tumor cells and eliminate senescent cells that accumulate after irradiation or in old mice. Ouabain also eliminates senescent preneoplastic cells. Our findings suggest that cardiac glycosides may be effective anti-cancer drugs by acting through multiple mechanism. Given the broad range of senescent cells targeted by cardiac glycosides their use against age-related diseases warrants further exploration.
Topics: Animals; Antineoplastic Agents; Apoptosis; Cardiac Glycosides; Cellular Senescence; Humans; Mice; Ouabain; Quercetin; Rats
PubMed: 31799499
DOI: 10.1038/s42255-019-0122-z -
Scientific Reports Jul 2022Zika virus (ZIKV) is an emerging arbovirus associated with neurological disorders. Currently, no specific vaccines or antivirals are available to treat the ZIKV...
Zika virus (ZIKV) is an emerging arbovirus associated with neurological disorders. Currently, no specific vaccines or antivirals are available to treat the ZIKV infection. Ouabain, a cardiotonic steroid known as Na/K-ATPase inhibitor, has been previously described as an immunomodulatory substance by our group. Here, we evaluated for the first time the antiviral activity of this promising substance against a Brazilian ZIKV strain. Vero cells were treated with different concentrations of ouabain before and after the infection with ZIKV. The antiviral effect was evaluated by the TCID method and RT-qPCR. Ouabain presented a dose-dependent inhibitory effect against ZIKV, mainly when added post infection. The reduction of infectious virus was accompanied by a decrease in ZIKV RNA levels, suggesting that the mechanism of ZIKV inhibition by ouabain occurred at the replication step. In addition, our in silico data demonstrated a conformational stability and favorable binding free energy of ouabain in the biding sites of the NS5-RdRp and NS3-helicase proteins, which could be related to its mechanism of action. Taken together, these data demonstrate the antiviral activity of ouabain against a Brazilian ZIKV strain and evidence the potential of cardiotonic steroids as promising antiviral agents.
Topics: Animals; Antiviral Agents; Brazil; Cardiac Glycosides; Chlorocebus aethiops; Ouabain; Vero Cells; Virus Replication; Zika Virus; Zika Virus Infection
PubMed: 35871157
DOI: 10.1038/s41598-022-14243-5 -
Current Opinion in Nephrology and... Jan 2013Endogenous cardiotonic steroids (CTS) exert long-term effects on salt and blood pressure homeostasis. Here we discuss recent observations on mechanisms of salt... (Review)
Review
PURPOSE OF REVIEW
Endogenous cardiotonic steroids (CTS) exert long-term effects on salt and blood pressure homeostasis. Here we discuss recent observations on mechanisms of salt sensitivity that involve endogenous ouabain and novel pathways in the brain and discuss their possible relationship to arterial and renal function in hypertension.
RECENT FINDINGS
Chronic elevation of brain sodium promotes sustained hypertension mediated by central endogenous ouabain and the Na(+) pump α-2 catalytic subunit. The intermediary pressor mechanism in the brain involves aldosterone biosynthesis, activation of mineralocorticoid receptors and increased epithelial sodium channel activity. In the periphery, elevated plasma CTS raise contractility and blood pressure by augmentation of sympathetic nerve responses, increasing arterial Ca(2+) signaling and blunting nitric oxide production in the renal medulla and collecting ducts.
SUMMARY
Endogenous ouabain in the brain appears to play a critical role in salt sensitivity and hypertension. In the periphery, the J-shaped relationship of plasma endogenous ouabain in response to short-term changes in salt balance in humans raises the possibility that endogenous ouabain contributes to the increased risk of adverse cardiovascular events associated with both low and high salt intakes.
Topics: Animals; Blood Pressure; Brain; Homeostasis; Humans; Hypertension; Ouabain; Sodium Chloride
PubMed: 23207724
DOI: 10.1097/MNH.0b013e32835b36ec -
Inflammopharmacology Dec 2021Ouabain is a cardiac steroid hormone with immunomodulatory effects. It inhibits neutrophils migration induced by different stimuli, but little is known about the...
Ouabain is a cardiac steroid hormone with immunomodulatory effects. It inhibits neutrophils migration induced by different stimuli, but little is known about the mechanisms involved in this effect. Thus, the aim of this study was to evaluate the ouabain effect on chemotactic signaling pathways in neutrophils. For that, mice neutrophils were isolated from bone marrow, treated with ouabain (1, 10, and 100 nM) for 2 h, submitted to transwell chemotaxis assay and flow cytometry analysis of Akt, ERK, JNK, and p38 phosphorylation induced by zymosan. Ouabain treatment (1, 10 and, 100 nM) reduces neutrophil chemotaxis induced by chemotactic peptide fMLP, but this substance did not inhibit Akt, ERK, and JNK activation induced by zymosan. However, ouabain (1 and 10 nM) reduced p38 phosphorylation in zymosan-stimulated neutrophils. These results suggest that ouabain may interfere in neutrophil migration through p38 MAPK inhibition.
Topics: Animals; Cell Movement; Chemotaxis, Leukocyte; Dose-Response Relationship, Drug; Female; Flow Cytometry; Mice; Neutrophils; Ouabain; Phosphorylation; Signal Transduction; p38 Mitogen-Activated Protein Kinases
PubMed: 34792671
DOI: 10.1007/s10787-021-00882-z -
Molecules (Basel, Switzerland) May 2017Ouabain and other cardenolides are steroidal compounds originally discovered in plants. Cardenolides were first used as poisons, but after finding their beneficial... (Review)
Review
Ouabain and other cardenolides are steroidal compounds originally discovered in plants. Cardenolides were first used as poisons, but after finding their beneficial cardiotonic effects, they were rapidly included in the medical pharmacopeia. The use of cardenolides to treat congestive heart failure remained empirical for centuries and only relatively recently, their mechanisms of action became better understood. A breakthrough came with the discovery that ouabain and other cardenolides exist as endogenous compounds that circulate in the bloodstream of mammals. This elevated these compounds to the category of hormones and opened new lines of investigation directed to further study their biological role. Another important discovery was the finding that the effect of ouabain was mediated not only by inhibition of the activity of the Na,K-ATPase (NKA), but by the unexpected role of NKA as a receptor and a signal transducer, which activates a complex cascade of intracellular second messengers in the cell. This broadened the interest for ouabain and showed that it exerts actions that go beyond its cardiotonic effect. It is now clear that ouabain regulates multiple cell functions, including cell proliferation and hypertrophy, apoptosis, cell adhesion, cell migration, and cell metabolism in a cell and tissue type specific manner. This review article focuses on the cardenolide ouabain and discusses its various in vitro and in vivo effects, its role as an endogenous compound, its mechanisms of action, and its potential use as a therapeutic agent; placing especial emphasis on our findings of ouabain as a pro-cystogenic agent in autosomal dominant polycystic kidney disease (ADPKD).
Topics: Animals; Cardiotonic Agents; Cell Communication; Humans; Kidney; Ouabain; Polycystic Kidney, Autosomal Dominant; Signal Transduction
PubMed: 28467389
DOI: 10.3390/molecules22050729 -
International Journal of Molecular... Jul 2018The endogenous ouabain (EO) is a steroid hormone secreted by the adrenal gland with cardio-tonic effects. In this article, we have reviewed and summarized the most... (Review)
Review
The endogenous ouabain (EO) is a steroid hormone secreted by the adrenal gland with cardio-tonic effects. In this article, we have reviewed and summarized the most recent reports about EO, particularly with regard to how it may interact with specific genetic backgrounds. We have focused our attention on the EO’s potential pathogenic role in several diseases, including renal failure, essential hypertension and heart failure. Notably, these reports have demonstrated that EO acts as a pro-hypertrophic and growth-promoting hormone, which might lead to a cardiac remodeling affecting cardiovascular functions and structures. In addition, a possible role of EO in the development of acute kidney injury has been hypothesized. During the last decays, many important improvements permitted a deeper understanding of EO’s metabolisms and functions, including the characteristics of its receptor and the effects of its activation. Such progresses indicated that EO has significant implications in the pathogenesis of many common diseases. The patho-physiological role of EO in the development of hypertension and other cardiac and renal complications have laid the basis for the development of a new selective compound that could selectively modulate the genetic and molecular mechanisms involved in EO’s action. It is evident that the knowledge of EO has incredibly increased; however, many important areas remain to be further investigated.
Topics: Animals; Calmodulin-Binding Proteins; Humans; Hypertension; Kidney Diseases; Ouabain
PubMed: 29970843
DOI: 10.3390/ijms19071948 -
BioMed Research International 2015Cellular swelling is controlled by an active mechanism of cell volume regulation driven by a Na(+)/K(+)-dependent ATPase and by aquaporins which translocate water along... (Review)
Review
Cellular swelling is controlled by an active mechanism of cell volume regulation driven by a Na(+)/K(+)-dependent ATPase and by aquaporins which translocate water along the osmotic gradient. Na(+)/K(+)-pump may be blocked by ouabain, a digitalic derivative, by inhibition of ATP, or by drastic ion alterations of extracellular fluid. However, it has been observed that some tissues are still able to control their volume despite the presence of ouabain, suggesting the existence of other mechanisms of cell volume control. In 1977, by correlating electron microscopy observation with ion and water composition of liver slices incubated in different metabolic conditions in the presence or absence of ouabain, we observed that hepatocytes were able to control their volume extruding water and recovering ion composition in the presence of ouabain. In particular, hepatocytes were able to sequester ions and water in intracellular vesicles and then secrete them at the bile canaliculus pole. We named this "vesicular mechanism of cell volume control." Afterward, this mechanism has been confirmed by us and other laboratories in several mammalian tissues. This review summarizes evidences regarding this mechanism, problems that are still pending, and questions that need to be answered. Finally, we shortly review the importance of cell volume control in some human pathological conditions.
Topics: Animals; Cell Size; Cytoplasmic Vesicles; Humans; Ion Transport; Ouabain; Sodium-Potassium-Exchanging ATPase; Water-Electrolyte Balance
PubMed: 25866786
DOI: 10.1155/2015/487256 -
Cell Communication and Signaling : CCS Oct 2023Acute myeloid leukemia (AML) is an aggressive hematologic malignancy characterized by an accumulation of immature leukemic myeloblasts initiating from leukemic stem...
BACKGROUND
Acute myeloid leukemia (AML) is an aggressive hematologic malignancy characterized by an accumulation of immature leukemic myeloblasts initiating from leukemic stem cells (LSCs)-the subpopulation that is also considered the root cause of chemotherapy resistance. Repurposing cardiac glycosides to treat cancers has gained increasing attention and supporting evidence, but how cardiac glycosides effectively target LSCs, e.g., whether it involves cell differentiation, remains largely unexplored.
METHODS
Digoxin, a user-designed digitoxigenin-α-L-rhamnoside (D6-MA), and ouabain were tested against various human AML-derived cells with different maturation phenotypes. Herein, we established two study models to specifically determine the effects of cardiac glycosides on LSC death and differentiation-one allowed change in dynamics of LSCs and leukemic progenitor cells (LPCs), while another maintained their undifferentiated status. Regulatory mechanisms underlying cardiac glycoside-induced cytotoxicity were investigated and linked to cell cycle distribution and apoptotic machinery.
RESULTS
Primitive AML cells containing CD34 LSCs/LPCs were very responsive to nanomolar concentrations of cardiac glycosides, with ouabain showing the greatest efficiency. Ouabain preferentially induces caspase-dependent apoptosis in LSCs, independent of its cell differentiation status, as evidenced by (i) the tremendous induction of apoptosis by ouabain in AML cells that acquired less than 15% differentiation and (ii) the higher rate of apoptosis in enriched LSCs than in LPCs. We sorted LSCs and LPCs according to their cell cycle distribution into G0/G1, S, and G2/M cells and revealed that G0/G1 cells in LSCs, which was its major subpopulation, were the top ouabain responders, indicating that the difference in ouabain sensitivity between LSCs and LPCs involved both distinct cell cycle distribution and intrinsic apoptosis regulatory mechanisms. Further, Mcl-1 and c-Myc, which were differentially expressed in LSCs and LPCs, were found to be the key apoptosis mediators that determined ouabain sensitivity in AML cells. Ouabain induces a more rapid loss of Mcl-1 and c-Myc in LSCs than in LPCs via the mechanisms that in part involve an inhibition of Mcl-1 protein synthesis and an induction of c-Myc degradation.
CONCLUSIONS
Our data provide new insight for repurposing cardiac glycosides for the treatment of relapsed/refractory AML through targeting LSCs via distinct cell cycle and apoptosis machinery. Video Abstract.
Topics: Humans; Cardiac Glycosides; Ouabain; Myeloid Cell Leukemia Sequence 1 Protein; Leukemia, Myeloid, Acute; Cell Differentiation; Stem Cells; Neoplastic Stem Cells; Apoptosis
PubMed: 37828578
DOI: 10.1186/s12964-023-01317-8 -
American Journal of Physiology.... Mar 2006The genetic and environmental heterogeneity of essential hypertension is responsible for the individual variability of antihypertensive therapy. An understanding of the... (Review)
Review
The genetic and environmental heterogeneity of essential hypertension is responsible for the individual variability of antihypertensive therapy. An understanding of the molecular mechanisms underlying hypertension and related organ complications is a key aspect for developing new, effective, and safe antihypertensive agents able to cure the cause of the disease. Two mechanisms, among others, are involved in determining the abnormalities of tubular Na+ reabsorption observed in essential hypertension: the polymorphism of the cytoskeletal protein alpha-adducin and the increased circulating levels of endogenous ouabain (EO). Both lead to increased activity and expression of the renal Na+-K+ pump, the driving force for tubular Na transport. Morphological and functional vascular alterations have also been associated with EO. Rostafuroxin (PST 2238) is a new oral antihypertensive agent able to selectively antagonize EO, adducin pressor, and molecular effects. It is endowed with high potency and efficacy in reducing blood pressure and preventing organ hypertrophy in animal models representative of both adducin and EO mechanisms. At molecular level, in the kidney, Rostafuroxin antagonizes EO triggering of the Src-epidermal growth factor receptor (EGFr)-dependent signaling pathway leading to renal Na+-K+ pump, and ERK tyrosine phosphorylation and activation. In the vasculature, it normalizes the increased myogenic tone caused by nanomolar ouabain. A very high safety ratio and an absence of interaction with other mechanisms involved in blood pressure regulation, together with initial evidence of high tolerability and efficacy in hypertensive patients, indicate Rostafuroxin as the first example of a new class of antihypertensive agents designed to antagonize adducin and EO-hypertensive mechanisms.
Topics: Androstanols; Animals; Antihypertensive Agents; Blood Vessels; Calmodulin-Binding Proteins; Humans; Hypertension; Kidney; Ouabain; Sodium-Potassium-Exchanging ATPase; Treatment Outcome
PubMed: 16467500
DOI: 10.1152/ajpregu.00518.2005 -
British Journal of Pharmacology Apr 2022Na /K -ATPase, a transmembrane protein essential for maintaining the electrochemical gradient across the plasma membrane, acts as a receptor for cardiotonic steroids... (Review)
Review
Na /K -ATPase, a transmembrane protein essential for maintaining the electrochemical gradient across the plasma membrane, acts as a receptor for cardiotonic steroids such as ouabain. Cardiotonic steroids binding to Na /K -ATPase triggers signalling pathways or inhibits Na /K -ATPas activity in a concentration-dependent manner, resulting in a modulation of Ca levels, which are essential for homeostasis in neurons. However, most of the pharmacological strategies for avoiding neuronal death do not target Na /K -ATPase activity due to its complexity and the poor understanding of the mechanisms involved in Na /K -ATPase modulation. The present review aims to discuss two points regarding the interplay between Na /K -ATPase and Ca signalling in the brain. One, Na /K -ATPase impairment causing illness and neuronal death due to Ca signalling and two, benefits to the brain by modulating Na /K -ATPase activity. These interactions play an essential role in neuronal cell fate determination and are relevant to find new targets for the treatment of neurodegenerative diseases. LINKED ARTICLES: This article is part of a themed issue on Building Bridges in Neuropharmacology. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v179.8/issuetoc.
Topics: Calcium; Calcium Signaling; Cardiac Glycosides; Ions; Neurons; Ouabain; Sodium; Sodium-Potassium-Exchanging ATPase
PubMed: 33644859
DOI: 10.1111/bph.15419