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Biochemical Pharmacology Apr 2024We previously showed that digitoxin inhibits angiogenesis and cancer cell proliferation and migration and these effects were associated to protein tyrosine kinase 2...
We previously showed that digitoxin inhibits angiogenesis and cancer cell proliferation and migration and these effects were associated to protein tyrosine kinase 2 (FAK) inhibition. Considering the interactions between FAK and Rho GTPases regulating cell cytoskeleton and movement, we investigated the involvement of RhoA and Rac1 in the antiangiogenic effect of digitoxin. Phalloidin staining of human umbilical vein endothelial cells (HUVECs) showed the formation of stress fibers in cells treated with 10 nM digitoxin. By Rhotekin- and Pak1- pull down assays, detecting the GTP-bound form of GTPases, we observed that digitoxin (10-25 nM) induced sustained (0.5-6 h) RhoA activation with no effect on Rac1. Furthermore, inhibition of HUVEC migration and capillary-like tube formation by digitoxin was counteracted by hindering RhoA-ROCK axis with RhoA silencing or Y-27632 treatment. Digitoxin did not decrease p190RhoGAP phosphorylation at Tyr1105 (a site targeted by FAK), suggesting that RhoA activation was independent from FAK inhibition. Because increasing evidence points to a redox regulation of RhoA, we measured intracellular ROS and found that digitoxin treatment enhanced ROS levels in a concentration-dependent manner (1-25 nM). Notably, the flavoprotein inhibitor DPI or the pan-NADPH oxidase (NOX) inhibitor VAS-2870 antagonized both ROS increase and RhoA activation by digitoxin. Our results provide evidence that inhibition of HUVEC migration and tube formation by digitoxin is dependent on ROS production by endothelial NOX, which leads to the activation of RhoA/ROCK pathway. Digitoxin effects on proteins regulating cytoskeletal organization and cell motility could have a wider impact on cancer progression, beyond the antiangiogenic activity.
Topics: Humans; Reactive Oxygen Species; Digitoxin; Human Umbilical Vein Endothelial Cells; Focal Adhesion Kinase 1; Phosphorylation; Cell Movement; NADPH Oxidases; rhoA GTP-Binding Protein; rho-Associated Kinases
PubMed: 38342347
DOI: 10.1016/j.bcp.2024.116049 -
British Journal of Clinical Pharmacology Aug 19821 Nine healthy volunteers received single 1 mg intravenous doses of digitoxin, following which serum digitoxin concentrations were measured at multiple points in time...
1 Nine healthy volunteers received single 1 mg intravenous doses of digitoxin, following which serum digitoxin concentrations were measured at multiple points in time over the next 14 days. 2 Mean kinetic variables for digitoxin were: volume of distribution, 0.76 l/kg; elimination half-life, 8 days; total clearance, 0.049 ml min-1 kg-1. 3 After a drug-free interval of at least 4 months, subjects took 0.07 mg of oral digitoxin daily for 28 consecutive days. Serum digitoxin concentrations were measured during the period of dosage and in the 21 day post-dosage washout. 4 Digitoxin accumulation was slow, proceeding with a mean half-life (7.9 days) that was nearly identical to the single-dose half-life. However, the two were not significantly correlated. 5 Mean observed steady-state serum concentrations (15.4 ng/ml) also were nearly identical to those predicted from the single-dose study (15.3 ng/ml), but again the two were not significantly correlated. 6 Steady state is very slowly attained after initiation of maintenance therapy with digitoxin. The kinetic data suggest that a loading dose on the average should be 12 times the maintenance dose.
Topics: Adult; Digitoxin; Female; Humans; Kinetics; Male
PubMed: 7104174
DOI: 10.1111/j.1365-2125.1982.tb01966.x -
Journal of Virology Feb 2017The dependence of adenovirus on the host pre-RNA splicing machinery for expression of its complete genome potentially makes it vulnerable to modulators of RNA splicing,...
UNLABELLED
The dependence of adenovirus on the host pre-RNA splicing machinery for expression of its complete genome potentially makes it vulnerable to modulators of RNA splicing, such as digoxin and digitoxin. Both drugs reduced the yields of four human adenoviruses (HAdV-A31, -B35, and -C5 and a species D conjunctivitis isolate) by at least 2 to 3 logs by affecting one or more steps needed for genome replication. Immediate early E1A protein levels are unaffected by the drugs, but synthesis of the delayed protein E4orf6 and the major late capsid protein hexon is compromised. Quantitative reverse transcription-PCR (qRT-PCR) analyses revealed that both drugs altered E1A RNA splicing (favoring the production of 13S over 12S RNA) early in infection and partially blocked the transition from 12S and 13S to 9S RNA at late stages of virus replication. Expression of multiple late viral protein mRNAs was lost in the presence of either drug, consistent with the observed block in viral DNA replication. The antiviral effect was dependent on the continued presence of the drug and was rapidly reversible. RIDK34, a derivative of convallotoxin, although having more potent antiviral activity, did not show an improved selectivity index. All three drugs reduced metabolic activity to some degree without evidence of cell death. By blocking adenovirus replication at one or more steps beyond the onset of E1A expression and prior to genome replication, digoxin and digitoxin show potential as antiviral agents for treatment of serious adenovirus infections. Furthermore, understanding the mechanism(s) by which digoxin and digitoxin inhibit adenovirus replication will guide the development of novel antiviral therapies.
IMPORTANCE
Despite human adenoviruses being a common and, in some instances, life-threating pathogen in humans, there are few well-tolerated therapies. In this report, we demonstrate that two cardiotonic steroids already in use in humans, digoxin and digitoxin, are potent inhibitors of multiple adenovirus species. A synthetic derivative of the cardiotonic steroid convallotoxin was even more potent than digoxin and digitoxin when tested with HAdV-C5. These drugs alter the cascade of adenovirus gene expression, acting after initiation of early gene expression to block viral DNA replication and synthesis of viral structural proteins. These findings validate a novel approach to treating adenovirus infections through the modulation of host cell processes.
Topics: Adenoviridae; Antiviral Agents; Cardiac Glycosides; Cell Line; DNA Replication; DNA, Viral; Digitoxin; Digoxin; Gene Expression Regulation, Viral; Humans; Virus Replication
PubMed: 27881644
DOI: 10.1128/JVI.01623-16 -
Biochimica Et Biophysica Acta. General... Nov 2020Cardiac glycosides (CGs), such as digitoxin, are traditionally used for treatment of congestive heart failure; recently they also gained attention for their anticancer...
BACKGROUND
Cardiac glycosides (CGs), such as digitoxin, are traditionally used for treatment of congestive heart failure; recently they also gained attention for their anticancer properties. Previous studies showed that digitoxin and a synthetic L-sugar monosaccharide analog treatment decreases cancer cell proliferation, increases apoptosis, and pro-adhesion abilities; however, no reports are available on their potential to alter lung cancer cell cytoskeleton structure and reduce migratory ability. Herein, we investigated the anticancer effects of digitoxin and its analog, digitoxigenin-α-L-rhamnoside (D6MA), to establish whether cytoskeleton reorganization and reduced motility are drug-induced cellular outcomes.
METHODS
We treated non-small cell lung carcinoma cells (NSCLCs) with sub-therapeutic, therapeutic, and toxic concentrations of digitoxin and D6MA respectively, followed by both single point and real-time assays to evaluate changes in cellular gene and protein expression, adhesion, elasticity, and migration.
RESULTS
Digitoxin and D6MA induced a decrease in matrix metalloproteinases expression via altered focal adhesion signaling and a suppression of the phosphoinositide 3-kinases / protein kinase B pathway which lead to enhanced adhesion, altered elasticity, and reduced motility of NSCLCs. Global gene expression analysis identified dose-dependent changes to nuclear factor kappa-light-chain-enhancer, epithelial tumor, and microtubule dynamics signaling.
CONCLUSIONS
Our study demonstrates that digitoxin and D6MA can target antitumor signaling pathways to alter NSCLC cytoskeleton and migratory ability to thus potentially reduce their tumorigenicity.
SIGNIFICANCE
Discovering signaling pathways that control cancer's cell phenotype and how such pathways are affected by CG treatment will potentially allow for active usage of synthetic CG analogs as therapeutic agents in advanced lung conditions.
Topics: Antineoplastic Agents; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Cell Movement; Cytoskeleton; Digitoxin; Humans; Lung Neoplasms
PubMed: 32679249
DOI: 10.1016/j.bbagen.2020.129683 -
Inhibitory Effects of Digoxin and Digitoxin on Cell Growth in Human Ovarian Cancer Cell Line SKOV-3.Integrative Cancer Therapies 2021Cardiac glycosides (CGs) possess a chemical structure similar to steroids, and are inhibitors of the sodium potassium pump. An anti-tumor effect of CGs in breast and...
BACKGROUND
Cardiac glycosides (CGs) possess a chemical structure similar to steroids, and are inhibitors of the sodium potassium pump. An anti-tumor effect of CGs in breast and prostate cancers has been reported, but the effect of CGs on ovarian cancer is still unclear.
AIMS
In this study, the effects of CGs on proliferation, cytotoxicity and cell cycle of ovarian cancer cell line (SKOV-3) have been investigated.
PROCEDURE
The cell proliferation and cytotoxicity were detected by MTT assay and LDH activity assay, respectively. CGs, at concentrations higher than IC50, decreased cell proliferation and showed increased cytotoxicity toward SKOV-3 cells. The colony-formation ability was reduced after treatment with digoxin and digitoxin for 10 days. Furthermore, we explored the effect of digoxin and digitoxin on the distribution of cell cycle by flow cytometry.
RESULTS
Results revealed that both digoxin and digitoxin led to cell cycle arrest in G/G phase with 24 or 48 hours, but the arrest of G/G phase was not observed at 72 hours. We evaluated the percentage of hypodiploid cell population as an index of the cellular fragments through flow cytometry. The data indicated that cellular fragments were significantly increased by treating with digitoxin at the concentrations of IC50 and 10 M for 72 hours.
CONCLUSION
Taken together, these data suggest that CGs decreased cell proliferation and increased cytotoxicity through cell cycle arrest at the G/G phase. CGs have anti-tumor effect in SKOV-3 cells and might be a potential therapeutic drug for ovarian cancer. Since this study is a preliminary investigation of CGs on SKOV-3 cells, more experiments might be performed in the future. Furthermore, more ovarian cancer cell lines might also be employed in the future studies to confirm the effect of CGs in ovarian cancer.
Topics: Cell Cycle; Cell Line; Cell Proliferation; Digitoxin; Digoxin; Female; Humans; Male; Ovarian Neoplasms
PubMed: 33736483
DOI: 10.1177/15347354211002662 -
Tidsskrift For Den Norske Laegeforening... Jul 2010
Topics: Anti-Arrhythmia Agents; Cardiotonic Agents; Digitalis Glycosides; Digitoxin; Digoxin; Humans; Treatment Outcome
PubMed: 20596094
DOI: 10.4045/tidsskr.10.0523 -
BMC Cancer 2001Digitoxin induces apoptosis in different human malignant cell lines in vitro. In this paper we investigated if patients taking digitoxin for cardiac disease have a...
BACKGROUND
Digitoxin induces apoptosis in different human malignant cell lines in vitro. In this paper we investigated if patients taking digitoxin for cardiac disease have a different cancer incidence compared to the general population.
METHODS
Computer stored data on digitoxin concentrations in plasma from 9271 patients with cardiac disease were used to define a user population. Age and sex matched controls from the Norwegian Cancer Registry were used to calculate the number of expected cancer cases.
RESULTS
The population on digitoxin showed a higher incidence of cancer compared to the control population. However, an additional analysis showed that the population on digitoxin had a general increased risk of cancer already, before the start on digitoxin. Leukemia/lymphoma were the cancer types which stood out with the highest risk in the digitoxin population before starting on digitoxin. This indicates that yet unknown risk factors exist for cardiovascular disease and lymphoproliferative cancer. An internal dose-response analysis revealed a relationship between high plasma concentration of digitoxin and a lower risk for leukemia/lymphoma and for cancer of the kidney/urinary tract.
CONCLUSION
Morbidity and mortality are high in the population on digitoxin, due to high age and cardiac disease. These factors disturb efforts to isolate an eventual anticancer effect of digitoxin in this setting. Still, the results may indicate an anticancer effect of digitoxin for leukemia/lymphoma and kidney/urinary tract cancers. Prospective clinical cancer trials have to be done to find out if digitoxin and other cardiac glycosides are useful as anticancer agents.
Topics: Age Factors; Aged; Anti-Arrhythmia Agents; Case-Control Studies; Cohort Studies; Digitoxin; Dose-Response Relationship, Drug; Female; Heart Diseases; Humans; Incidence; Male; Neoplasms
PubMed: 11532201
DOI: 10.1186/1471-2407-1-11 -
Canadian Medical Association Journal Aug 1979
Topics: Arrhythmias, Cardiac; Barbiturates; Digitalis Glycosides; Digitoxin; Digoxin; Diuretics; Drug Interactions; Humans; Hypokalemia; Phenylbutazone; Potassium; Quinidine
PubMed: 466599
DOI: No ID Found -
Frontiers in Molecular Biosciences 2023Digitoxin is a cardiac glycoside used to treat heart failure and heart arrhythmia. However, its therapeutic concentration range is very narrow. High doses of digitoxin...
Digitoxin is a cardiac glycoside used to treat heart failure and heart arrhythmia. However, its therapeutic concentration range is very narrow. High doses of digitoxin are associated with severe side effects; therefore, it is necessary to develop the delivery system which can control the plasma levels of it. In this context, the binding of lysozyme, an important protein having many applications, with digitoxin has been studied to see the ability of the former as a carrier. The studies were carried out using both experimental and computational methods. The intrinsic fluorescence of lysozyme increased on the addition of digitoxin. Fluorescence results suggested that there was a strong interaction between lysozyme and digitoxin which was favored, mainly, by hydrophobic forces. Further, digitoxin affected the secondary structure of lysozyme slightly by causing the partial unfolding of lysozyme. The preferred binding site of digitoxin within lysozyme was the large cavity of the protein. Molecular docking studies also established the principal role of hydrophobic forces in the binding with a significant support of hydrogen bonding. Frontier molecular orbitals of free digitoxin and in complexation with lysozyme were also computed and discussed. The findings from molecular dynamics simulation studies elucidate that, when contrasted with the first and third conformations of the digitoxin-bound lysozyme complex, the second conformation promotes structural stability, reduces flexibility, and enhances the compactness and folding properties of lysozyme. The overall study shows that lysozyme could act as a potential carrier for digitoxin in pharmaceutical formulations.
PubMed: 38187092
DOI: 10.3389/fmolb.2023.1327740 -
Insects Apr 2019Cardiac glycosides, cardenolides and bufadienolides, are elaborated by several plant or animal species to prevent grazing or predation. Entomologists have characterized... (Review)
Review
Cardiac glycosides, cardenolides and bufadienolides, are elaborated by several plant or animal species to prevent grazing or predation. Entomologists have characterized several insect species that have evolved the ability to sequester these glycosides in their tissues to reduce their palatability and, thus, reduce predation. Cardiac glycosides are known to interact with the sodium- and potassium-activated adenosine triphosphatase, or sodium pump, through a specific receptor-binding site. Over the last couple of decades, and since entomologic studies, it has become clear that mammals synthesize endogenous cardenolides that closely resemble or are identical to compounds of plant origin and those sequestered by insects. The most important of these are ouabain-like compounds. These compounds are essential for the regulation of normal ionic physiology in mammals. Importantly, at physiologic picomolar or nanomolar concentrations, endogenous ouabain, a cardenolide, stimulates the sodium pump, activates second messengers, and may even function as a growth factor. This is in contrast to the pharmacologic or toxic micromolar or milimolar concentrations achieved after consumption of exogenous cardenolides (by consuming medications, plants, or insects), which inhibit the pump and result in either a desired medical outcome, or the toxic consequence of sodium pump inhibition.
PubMed: 30974764
DOI: 10.3390/insects10040102