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Journal of Translational Medicine May 2022RNA adenosine modifications, which are primarily mediated by "writer" enzymes (RMWs), play a key role in epigenetic regulation in various biological processes, including...
BACKGROUND
RNA adenosine modifications, which are primarily mediated by "writer" enzymes (RMWs), play a key role in epigenetic regulation in various biological processes, including tumorigenesis. However, the expression and prognostic role of these genes in osteosarcoma (OS) remain unclear.
METHODS
Univariate and multivariate Cox analyses were used to construct the RMW signature for OS using Target datasets. RMW expression in OS tissue was detected by qPCR analysis. Xcell and GSVA were used to determine the relationship between RMWs and immune infiltration. The DGIdb and CMap databases were used for drug prediction. In vivo and in vitro experiments showed that strophanthidin elicited antitumor activity against OS.
RESULTS
A 3-RMW (CSTF2, ADAR and WTAP) prognostic signature in OS was constructed using the Target dataset and verified using GEO datasets and 63 independent OS tissues via qPCR analysis. High-risk OS patients had poor overall survival, and the prognostic signature was an independent prognostic factor for OS. Functional studies showed that tumour-, metabolism-, cell cycle- and immune-related pathways were related to high risk. Next, we found that RMW-derived high-risk patients exhibited increased infiltration of M2 macrophages and cDCs. Furthermore, we predicted the potential drugs for OS using the DGIdb and CMap databases. In vivo and in vitro experiments showed that strophanthidin elicited antitumor activity against OS by repressing cell growth and inducing cell cycle arrest at the G1 phase.
CONCLUSION
The 3-RWM-based prognostic signature established in this study is a novel gene signature associated with immune infiltration, and strophanthidin was identified as a candidate therapy for OS by repressing OS cell growth and the cell cycle.
Topics: Adenosine; Biomarkers, Tumor; Bone Neoplasms; Epigenesis, Genetic; Gene Expression Regulation, Neoplastic; Humans; Osteosarcoma; Prognosis; RNA; Strophanthidin
PubMed: 35568866
DOI: 10.1186/s12967-022-03415-6 -
Molecules (Basel, Switzerland) Sep 2021Docking profiles for (+)-strebloside, a cytotoxic cardiac glycoside identified from , and some of its derivatives and Na/K-ATPase have been investigated. In addition,...
Docking profiles for (+)-strebloside, a cytotoxic cardiac glycoside identified from , and some of its derivatives and Na/K-ATPase have been investigated. In addition, binding between (+)-strebloside and its aglycone, strophanthidin, and several of their other molecular targets, including FIH-1, HDAC, KEAP1 and MDM2 (negative regulators of Nrf2 and p53, respectively), NF-κB, and PI3K and Akt1, have been inspected and compared with those for digoxin and its aglycone, digoxigenin. The results showed that (+)-strebloside, digoxin, and their aglycones bind to KEAP1 and MDM2, while (+)-strebloside, strophanthidin, and digoxigenin dock to the active pocket of PI3K, and (+)-strebloside and digoxin interact with FIH-1. Thus, these cardiac glycosides could directly target HIF-1, Nrf2, and p53 protein-protein interactions, Na/K-ATPase, and PI3K to mediate their antitumor activity. Overall, (+)-strebloside seems more promising than digoxin for the development of potential anticancer agents.
Topics: Animals; Cardiac Glycosides; Humans; Kelch-Like ECH-Associated Protein 1; Molecular Docking Simulation; Structure-Activity Relationship
PubMed: 34577146
DOI: 10.3390/molecules26185675 -
Frontiers in Oncology 2019Lung cancer is the most prevalent in cancer-related deaths, while breast carcinoma is the second most dominant cancer in women, accounting for the most number of deaths...
Lung cancer is the most prevalent in cancer-related deaths, while breast carcinoma is the second most dominant cancer in women, accounting for the most number of deaths worldwide. Cancers are heterogeneous diseases that consist of several subtypes based on the presence or absence of hormone receptors and human epidermal growth factor receptor 2. Several drugs have been developed targeting cancer biomarkers; nonetheless, their efficiency are not adequate due to the high reemergence rate of cancers and fundamental or acquired resistance toward such drugs, which leads to partial therapeutic possibilities. Recent studies on cardiac glycosides (CGs) positioned them as potent cytotoxic agents that target multiple pathways to initiate apoptosis and autophagic cell death in many cancers. In the present study, our aim is to identify the anticancer activity of a naturally available CG (strophanthidin) in human breast (MCF-7), lung (A549), and liver cancer (HepG2) cells. Our results demonstrate a dose-dependent cytotoxic effect of strophanthidin in MCF-7, A549, and HepG2 cells, which was further supported by DNA damage on drug treatment. Strophanthidin arrested the cell cycle at the G2/M phase; this effect was further validated by checking the inhibited expressions of checkpoint and cyclin-dependent kinases in strophanthidin-induced cells. Moreover, strophanthidin inhibited the expression of several key proteins such as MEK1, PI3K, AKT, mTOR, Gsk3α, and β-catenin from MAPK, PI3K/AKT/mTOR, and Wnt/β-catenin signaling. The current study adequately exhibits the role of strophanthidin in modulating the expression of various key proteins involved in cell cycle arrest, apoptosis, and autophagic cell death. Our studies revealed that strophanthidin can interact with several key proteins from various pathways. Taken together, this study demonstrates the viability of strophanthidin as a promising anticancer agent, which may serve as a new anticancer drug.
PubMed: 32010609
DOI: 10.3389/fonc.2019.01469 -
PLoS Neglected Tropical Diseases Mar 2022Brucellosis is an infectious disease caused by bacteria of the genus Brucella. Although it is the most common zoonosis worldwide, there are increasing reports of drug...
BACKGROUND
Brucellosis is an infectious disease caused by bacteria of the genus Brucella. Although it is the most common zoonosis worldwide, there are increasing reports of drug resistance and cases of relapse after long term treatment with the existing drugs of choice. This study therefore aims at identifying possible natural inhibitors of Brucella melitensis Methionyl-tRNA synthetase through an in-silico approach.
METHODS
Using PyRx 0.8 virtual screening software, the target was docked against a library of natural compounds obtained from edible African plants. The compound, 2-({3-[(3,5-dichlorobenzyl) amino] propyl} amino) quinolin-4(1H)-one (OOU) which is a co-crystallized ligand with the target was used as the reference compound. Screening of the molecular descriptors of the compounds for bioavailability, pharmacokinetic properties, and bioactivity was performed using the SWISSADME, pkCSM, and Molinspiration web servers respectively. The Fpocket and PLIP webservers were used to perform the analyses of the binding pockets and the protein ligand interactions. Analysis of the time-resolved trajectories of the Apo and Holo forms of the target was performed using the Galaxy and MDWeb servers.
RESULTS
The lead compounds, Strophanthidin and Isopteropodin are present in Corchorus olitorius and Uncaria tomentosa (Cat's-claw) plants respectively. Isopteropodin had a binding affinity score of -8.9 kcal / ml with the target and had 17 anti-correlating residues in Pocket 1 after molecular dynamics simulation. The complex formed by Isopteropodin and the target had a total RMSD of 4.408 and a total RMSF of 9.8067. However, Strophanthidin formed 3 hydrogen bonds with the target at ILE21, GLY262 and LEU294, and induced a total RMSF of 5.4541 at Pocket 1.
CONCLUSION
Overall, Isopteropodin and Strophanthidin were found to be better drug candidates than OOU and they showed potentials to inhibit the Brucella melitensis Methionyl-tRNA synthetase at Pocket 1, hence abilities to treat brucellosis. In-vivo and in-vitro investigations are needed to further evaluate the efficacy and toxicity of the lead compounds.
Topics: Anti-Bacterial Agents; Brucella melitensis; Ligands; Methionine-tRNA Ligase; Molecular Dynamics Simulation
PubMed: 35312681
DOI: 10.1371/journal.pntd.0009799 -
The Journal of Physiology Nov 19911. A method is described for producing high yields of calcium-tolerant ventricular myocytes from guinea-pig hearts (73.4% rod-shaped cells, n = 19). Their action...
1. A method is described for producing high yields of calcium-tolerant ventricular myocytes from guinea-pig hearts (73.4% rod-shaped cells, n = 19). Their action potential (AP) and membrane currents were recorded using conventional microelectrodes and cell shortening was measured optically using a linear photodiode array. 2. The sensitivity of the guinea-pig Na(+)-K+ pump to strophanthidin (a rapidly acting digitalis analogue) was determined by measuring the inhibition of outward pump current by different doses. The pump was found to have a dissociation constant (KD) for strophanthidin of 1.11 x 10(-5) M, and 5 x 10(-4) M-strophanthidin inhibited the pump maximally. 3. Exposure to strophanthidin resulted in an initial lengthening followed by a shortening of the AP, and an increased contraction. Initial AP lengthening was associated with a more positive AP plateau which became more negative as the AP shortened. 4. There was a reversible reduction of Ca2+ current (ICa) during exposure to strophanthidin. ICa changed reciprocally with contraction and with a similar time course. 5. Strophanthidin exposure caused a reduction of ICa at all activating voltages, suggesting that it resulted in a reduction of Ca2+ conductance with little change of its voltage dependence. 6. The role of an increase of intracellular calcium (Cai2+) was investigated by impaling myocytes with microelectrodes containing BAPTA 1,2-bis (2-amino-phenoxy)ethane-N,N,N',N'-tetraacetic acid, a calcium chelator) to increase Cai2+ buffering. Strophanthidin still shortened the AP when BAPTA was present, suggesting that a rise of Cai2+ is not a major cause of AP shortening. 7. Although AP shortening was little affected, the decline of ICa with strophanthidin was markedly reduced when BAPTA was present, suggesting that a rise of Cai2+ was the cause of the ICa decline with strophanthidin. 8. When barium ions carried the current through Ca2+ channels, strophanthidin did not reduce Ca2+ channel current, suggesting that this compound does not have a direct inhibitory effect on the channel. 9. The results suggest that strophanthidin causes a reduction of ICa by increasing Cai2+, via the mechanism of Cai(2+)-dependent inactivation of ICa. The reduction of ICa at least partially explains the AP shortening and more negative plateau with strophanthidin. 10. The shortening of the AP, more negative plateau and reduced ICa have negative inotropic effects which oppose the direct positive inotropic effect of strophanthidin.
Topics: Action Potentials; Animals; Barium; Calcium; Dose-Response Relationship, Drug; Guinea Pigs; Heart; Heart Ventricles; Myocardial Contraction; Myocardium; Strophanthidin
PubMed: 1822522
DOI: 10.1113/jphysiol.1991.sp018819 -
The Journal of Clinical Investigation Jun 1974Isolated cat right ventricular papillary muscles were used to study the effects of antibodies with high affinity for ouabain and acetyl strophanthidin on myocardium... (Comparative Study)
Comparative Study
Isolated cat right ventricular papillary muscles were used to study the effects of antibodies with high affinity for ouabain and acetyl strophanthidin on myocardium exposed to these cardioactive steroids. Antibodies with average intrinsic affinity constants for ouabain and acetyl strophanthidin of the order of 10(8) M(-1) were raised in rabbits challenged by repeated injection of a conjugate of ouabain covalently linked to a poly D,L-alanyl derivative of human serum albumin. Effects were assessed in terms of time-course and extent of inotropy reversal, influence of experimentally induced ventricular failure, digitalis-antibody concentration relations, influence of digitalis-antibody complex on response to additionally added digitalis, and relation of antibody effects on digitalis-induced automaticity and contracture to reversal of inotropy. Specific antibody (but not control antibody) in 1.1-1.5-fold molar excess over cardioactive steroid concentrations blocked positive inotropic effects of ouabain and acetyl strophanthidin, and gradually reversed established contractile effects of these agents with a mean time for half-reversal of ouabain-induced inotropy of 124+/-6 (SEM) min and 37+/-3 min for half-reversal of acetyl strophanthidin-induced inotropy. Papillary muscles from cats with right ventricular failure induced by chronic pulmonary artery constriction responded similarly. Both normal and failing muscles returned to but not below levels of contractility existing before cardioactive steroid exposure, and time for half-reversal of inotropy by antibody was significantly shorter than time for half-reversal after removal of ouabain or acetyl strophanthidin by muscle bath washout alone. Presence of ouabain- or acetyl strophanthidin-antibody complex did not alter the myocardial contractile response to subsequently added cardioactive steroids. Spontaneous automaticity occurring as a toxic response to ouabain or acetyl strophanthidin in eight muscles was rapidly reversed by specific antibody at a time when positive inotropic effects were still fully manifest. Early contracture was also reversed by specific antibody. These studies provide further support for the concept that cardiac glycoside-specific antibodies are capable of reversing established cellular effects of cardioactive steroids.
Topics: Animals; Antibodies; Cardanolides; Cats; Depression, Chemical; Digitalis Glycosides; Heart; Heart Failure; Heart Ventricles; Humans; Immunologic Techniques; In Vitro Techniques; Myocardium; Ouabain; Papillary Muscles; Pulmonary Artery; Rabbits; Serum Albumin; Stimulation, Chemical; Stress, Mechanical; Time Factors
PubMed: 4598113
DOI: 10.1172/JCI107716 -
European Journal of Heart Failure Nov 2007Cardiac glycosides are characterized by a narrow therapeutic range with Ca2+-overload and arrhythmias occurring at higher concentrations. Data on cardiac glycosides in...
BACKGROUND
Cardiac glycosides are characterized by a narrow therapeutic range with Ca2+-overload and arrhythmias occurring at higher concentrations. Data on cardiac glycosides in isolated failing human myocardium are scarce and the frequency-dependent actions and toxicity of Strophanthidin have not yet been characterized.
AIMS
To determine inotropic responses and toxicity of Strophanthidin in failing human myocardium.
METHODS AND RESULTS
Experiments were performed in trabeculae from 64 end-stage failing hearts. Developed force, and intracellular [Ca2+]i and [Na+]i were recorded with Strophanthidin (0.01 to 1 micromol/L; 37 degrees C, 1 Hz) and compared to interventions with distinct mechanisms of action (elevated [Ca2+]o, Isoproterenol, and EMD57033). The effects of Strophanthidin on force-frequency behaviour were also assessed. Strophanthidin exerted concentration-dependent positive inotropic effects. These were paralleled by increases in intracellular [Na+] as well as increasing [Ca2+]i-transients and SR-Ca2+-load. At high concentrations (>0.5 micromol/L), Strophanthidin caused afterglimmers and aftercontractions, with declining developed force despite further increasing [Ca2+]i-transients. The force-frequency-relationship and diastolic function at higher pacing rates was worsened by Strophanthidin in a concentration-dependent manner.
CONCLUSIONS
Strophanthidin toxicity was dependent on concentration, calcium load, beating rate and beta-adrenergic receptor activation. Our data support the view that low doses, heart rate control and additional beta-adrenergic receptor blockade are essential in the use of cardiac glycosides in heart failure.
Topics: Cardiotonic Agents; Diastole; Female; Heart Failure; Humans; Isoproterenol; Male; Middle Aged; Myocardial Contraction; Sodium-Calcium Exchanger; Strophanthidin; Systole
PubMed: 17956764
DOI: 10.1016/j.ejheart.2007.08.004 -
International Journal of Molecular... Nov 2023Cardiac glycosides (CGs) constitute a group of steroid-like compounds renowned for their effectiveness in treating cardiovascular ailments. In recent times, there has...
Cardiac glycosides (CGs) constitute a group of steroid-like compounds renowned for their effectiveness in treating cardiovascular ailments. In recent times, there has been growing recognition of their potential use as drug leads in cancer treatment. In our prior research, we identified three highly promising CG compounds, namely lanatoside C (LC), peruvoside (PS), and strophanthidin (STR), which exhibited significant antitumor effects in lung, liver, and breast cancer cell lines. In this study, we investigated the therapeutic response of these CGs, with a particular focus on the MCF-7 breast cancer cell line. We conducted transcriptomic profiling and further validated the gene and protein expression changes induced by treatment through qRT-PCR, immunoblotting, and immunocytochemical analysis. Additionally, we demonstrated the interactions between the ligands and target proteins using the molecular docking approach. The transcriptome analysis revealed a cluster of genes with potential therapeutic targets involved in cytotoxicity, immunomodulation, and tumor-suppressor pathways. Subsequently, we focused on cross-validating the ten most significantly expressed genes, , , , , , , , , , and , through qRT-PCR, and their by confirming the consistent expression pattern with RNA-Seq data. Notably, among the most variable genes, we identified EGR1, the downstream effector of the MAPK signaling pathway, which performs the regulatory function in cell proliferation, tumor invasion, and immune regulation. Furthermore, we substantiated the influence of CG compounds on translational processes, resulting in an alteration in protein expression upon treatment. An additional analysis of ligand-protein interactions provided further evidence of the robust binding affinity between LC, PS, and STR and their respective protein targets. These findings underscore the intense anticancer activity of the investigated CGs, shedding light on potential target genes and elucidating the probable mechanism of action of CGs in breast cancer.
Topics: Humans; Female; Cardiac Glycosides; Breast Neoplasms; Glycosides; Molecular Docking Simulation; Signal Transduction; Gene Expression Profiling; Cell Line, Tumor; Cell Proliferation; Transcriptome; Early Growth Response Protein 1
PubMed: 37958905
DOI: 10.3390/ijms242115922 -
Journal of Neurophysiology Jan 2021The Na-K-ATPase (Na-K pump) is essential for setting resting membrane potential and restoring transmembrane Na and K gradients after neuronal firing, yet its roles in...
The Na-K-ATPase (Na-K pump) is essential for setting resting membrane potential and restoring transmembrane Na and K gradients after neuronal firing, yet its roles in developing neurons are not well understood. This study examined the contribution of the Na-K pump to resting membrane potential and membrane excitability of developing CA1 and CA3 neurons and its role in maintaining synchronous network bursting. Experiments were conducted in postnatal day (P)9 to P13 rat hippocampal slices using whole cell patch-clamp and extracellular field-potential recordings. Blockade of the Na-K pump with strophanthidin caused marked depolarization (23.1mV) in CA3 neurons but only a modest depolarization (3.3mV) in CA1 neurons. Regarding other membrane properties, strophanthidin differentially altered the voltage-current responses, input resistance, action-potential threshold and amplitude, rheobase, and input-output relationship in CA3 vs. CA1 neurons. At the network level, strophanthidin stopped synchronous epileptiform bursting in CA3 induced by 0 Mg and 4-aminopyridine. Furthermore, dual whole cell recordings revealed that strophanthidin disrupted the synchrony of CA3 neuronal firing. Finally, strophanthidin reduced spontaneous excitatory postsynaptic current (sEPSC) bursts (i.e., synchronous transmitter release) and transformed them into individual sEPSC events (i.e., nonsynchronous transmitter release). These data suggest that the Na-K pump plays a more profound role in membrane excitability in developing CA3 neurons than in CA1 neurons and that the pump is essential for the maintenance of synchronous network bursting in CA3. Compromised Na-K pump function leads to cessation of ongoing synchronous network activity, by desynchronizing neuronal firing and neurotransmitter release in the CA3 synaptic network. These findings have implications for the regulation of network excitability and seizure generation in the developing brain. Despite the extensive literature showing the importance of the Na-K pump in various neuronal functions, its roles in the developing brain are not well understood. This study reveals that the Na-K pump differentially regulates the excitability of CA3 and CA1 neurons in the developing hippocampus, and the pump activity is crucial for maintaining network activity. Compromised Na-K pump activity desynchronizes neuronal firing and transmitter release, leading to cessation of ongoing epileptiform network bursting.
Topics: Action Potentials; Animals; CA1 Region, Hippocampal; CA3 Region, Hippocampal; Excitatory Postsynaptic Potentials; Rats; Rats, Sprague-Dawley; Sodium-Potassium-Exchanging ATPase; Strophanthidin
PubMed: 33206576
DOI: 10.1152/jn.00453.2020 -
Blood Cancer Journal Jun 2018Therapy for acute myeloid leukemia (AML) involves intense cytotoxic treatment and yet approximately 70% of AML are refractory to initial therapy or eventually relapse....
Therapy for acute myeloid leukemia (AML) involves intense cytotoxic treatment and yet approximately 70% of AML are refractory to initial therapy or eventually relapse. This is at least partially driven by the chemo-resistant nature of the leukemic stem cells (LSCs) that sustain the disease, and therefore novel anti-LSC therapies could decrease relapses and improve survival. We performed in silico analysis of highly prognostic human AML LSC gene expression signatures using existing datasets of drug-gene interactions to identify compounds predicted to target LSC gene programs. Filtering against compounds that would inhibit a hematopoietic stem cell (HSC) gene signature resulted in a list of 151 anti-LSC candidates. Using a novel in vitro LSC assay, we screened 84 candidate compounds at multiple doses and confirmed 14 drugs that effectively eliminate human AML LSCs. Three drug families presenting with multiple hits, namely antihistamines (astemizole and terfenadine), cardiac glycosides (strophanthidin, digoxin and ouabain) and glucocorticoids (budesonide, halcinonide and mometasone), were validated for their activity against human primary AML samples. Our study demonstrates the efficacy of combining computational analysis of stem cell gene expression signatures with in vitro screening to identify novel compounds that target the therapy-resistant LSC at the root of relapse in AML.
Topics: Apoptosis; Biomarkers; Biomarkers, Tumor; Cell Cycle; Cell Differentiation; Cell Line, Tumor; Computational Biology; Cytarabine; Drug Discovery; Drug Screening Assays, Antitumor; Gene Expression Profiling; Hematopoietic Stem Cells; Humans; Leukemia, Myeloid, Acute; Molecular Targeted Therapy; Neoplastic Stem Cells; Transcriptome
PubMed: 29921955
DOI: 10.1038/s41408-018-0087-2