Ethacrynic Acid Research Articles

New Small-Molecule SERCA Inhibitors Enhance Treatment Efficacy in Lenvatinib-Resistant Papillary Thyroid Cancer.

Papillary thyroid cancer (PTC) is one of the most treatable forms of cancer, with many cases being fully curable. However, resistance to anticancer drugs often leads to metastasis or recurrence, contributing to the failure of cancer therapy and, ultimately, patient mortality. The mechanisms underlying molecular differences in patients with metastatic or recurrent PTC, particularly those resistant to anticancer drugs through epigenetic reprogramming, remain poorly understood. Consequently, refractory PTC presents a critical challenge, and effective therapeutic strategies are urgently needed. Therefore, this study aimed to identify small-molecule inhibitors to enhance treatment efficacy in lenvatinib-resistant PTC. We observed an increase in sarco/endoplasmic reticulum calcium ATPase (SERCA) levels in patient-derived lenvatinib-resistant PTC cells compared with lenvatinib-sensitive ones, highlighting its potential as a therapeutic target. We subsequently identified two SERCA inhibitors [candidates 40 (isoflurane) and 42 (ethacrynic acid)] through in silico screening. These candidates demonstrated significant tumor shrinkage in a xenograft tumor model and reduced cell viability in patient-derived lenvatinib-resistant PTC cells when used in combination with lenvatinib. Our findings have potential clinical value for the development of new combination therapies to effectively target highly malignant, anticancer drug-resistant cancers.

MMFA-DTA: Multimodal Feature Attention Fusion Network for Drug-Target Affinity Prediction for Drug Repurposing Against SARS-CoV-2.

The continuous emergence of novel infectious diseases poses a significant threat to global public health security, necessitating the development of small-molecule inhibitors that directly target pathogens. The RNA-dependent RNA polymerase (RdRp) and main protease (Mpro) of SARS-CoV-2 have been validated as potential key antiviral drug targets for the treatment of COVID-19. However, the conventional new drug R&D cycle takes 10-15 years, failing to meet the urgent needs during epidemics. Here, we propose a general multimodal deep learning framework for drug repurposing, MMFA-DTA, to enable rapid virtual screening of known drugs and significantly improve discovery efficiency. By extracting graph topological and sequence features from both small molecules and proteins, we design attention mechanisms to achieve dynamic fusion across modalities. Results demonstrate the superior performance of MMFA-DTA in drug-target affinity prediction over several state-of-the-art baseline methods on Davis and KIBA data sets, validating the benefits of heterogeneous information integration for representation learning and interaction modeling. Further fine-tuning on COVID-19-relevant bioactivity data enhances model predictions for critical SARS-CoV-2 enzymes. Case studies screening the FDA-approved drug library successfully identify etacrynic acid as the potential lead compound against both RdRp and Mpro. Molecular dynamics simulations further confirm the stability and binding affinity of etacrynic acid to these targets. This study proves the great potential and advantages of deep learning and drug repurposing strategies in supporting antiviral drug discovery. The proposed general and rapid response computational framework holds significance for preparedness against future public health events.

Loop diuretics inhibit kynurenic acid production and kynurenine aminotransferases activity in rat kidneys.

Loop diuretics became a cornerstone in the therapy of hypervolemia in patients with chronic kidney disease or heart failure. Apart from the influence on water and electrolyte balance, these drugs were shown to inhibit tissue fibrosis and renin-angiotensin-system activity. The kynurenine (KYN) pathway products are suggested to be uremic toxins. Kynurenic acid (KYNA) is synthesized by kynurenine aminotransferases (KATs) in the brain and periphery. The cardiovascular and renal effects of KYNA are well documented. However, high KYNA levels have been correlated with the rate of kidney damage and its complications. Our study aimed to assess the effect of loop diuretics, ethacrynic acid, furosemide, and torasemide on KYNA synthesis and KATs activity in rat kidneys in vitro. Quantitative analyses of KYNA were performed using fluorimetric HPLC detection. Additionally, molecular docking studies determined the possible interactions of investigated compounds with an active site of KAT I and KAT II. All studied drugs inhibited KYNA production in rat kidneys in vitro at 0.5-1.0mmol/l concentrations. Only ethacrynic acid at 1.0mmol/l concentration significantly lowered KAT I and KAT II activity in kidney homogenates, whereas other drugs were ineffective. Molecular docking results indicated the common binding site for each of the studied loop diuretics and KYNA. They suggested possible residues involved in their binding to the active site of both KAT I and KAT II model. Our study reveals that loop diuretics may decrease KYNA synthesis in rat kidneys in vitro. The presented results warrant further research in the context of KYN pathway activity regulation by loop diuretics.

Synthesis, characterization of novel mannich bases and their acetylcholinesterase and glutathione S-transferase inhibitory properties: An in vitro and in silico mechanism research

In this study, 4-((3,4-Dimethoxybenzylidene)amino)-5-alkyl(aryl)-2,4-dihydro-3H-1,2,4-triazol-3-ones (4a-g) reacted with formaldehyde and 2,6-dimethylmorpholine to obtain seven novel potential biologically active 4-((3,4-Dimethoxybenzylidene)amino)-2-((2,6-dimethylmorpholino)methyl)-5-alkyl(aryl)-2,4-dihydro-3H-1,2,4-triazol-3-ones (5a-g). The structures (5a-g) of newly synthesized compounds were characterized using FT-IR, 1H-NMR, and 13C-NMR spectral data. The synthesized compounds (5a-g) were investigated for it is in vitro enzyme inhibition properties. Results demonstrated that the newly synthesized compounds had valuable enzyme inhibition activities against acetylcholinesterase (AChE) and glutathione S-transferase (GST) enzymes. Their Ki values were calculated in the range of 0.96 ± 0.0557- 9.7967 ± 5.3105 µM, while their IC50 values were calculated in the range of 1.333–3.551 µM. Tacrine was used for AChE, Ethacrynic acid was used for GST as positive standard. Molecular docking studies revealed that compound 5b binds to AChE and compound 5f binds to GST with high affinity (−10.2 and −9.1 kcal/mol) in protein-ligand complexes. The stability of the ligand-protein complexes was confirmed by 100 ns molecular dynamics simulations.

Loop Diuretics: An Overview of Its History and Evolution.

The loop of Henle plays a key role in kidney function, especially in retaining solutes and concentrating urine. Diuretic agents, crucial for managing fluid overload and related conditions like hypertension and heart failure (HF), enhance water and electrolyte excretion. The history of diuretics dates back to 1775 with the discovery of Digitalis, evolving significantly with the introduction of chlorothiazide in 1957, which revolutionized diuretic therapy. Loop diuretics, developed in the 1950s and including drugs like torsemide, furosemide, and ethacrynic acid, are potent agents acting on the loop of Henle. They are vital for treating severe fluid overload conditions and require careful monitoring to manage potential side effects.

Development of a new experimental NMR strategy for covalent cysteine protease inhibitors screening: toward enhanced drug discovery.

In the development of antiviral drugs, proteases and polymerases are among the most important targets. Cysteine proteases, also known as thiol proteases, catalyze the degradation of proteins by cleaving peptide bonds using the nucleophilic thiol group of cysteine. As part of our research, we are examining how cysteine, an essential amino acid found in the active site of the main protease (Mpro) enzyme in SARS-CoV-2, interacts with electrophilic groups present in ethacrynic acid (EA) and compounds 4, 6, and 8 to form sulfur-carbon bonds. Nuclear magnetic resonance (NMR) spectroscopy was used to monitor the reaction rate between cysteine and Michael acceptors. We found that the inhibitory activity of these compounds towards Mpro is correlated to their chemical reactivity toward cysteine. This approach may serve as a valuable tool in drug development for detecting potential covalent inhibitors of Mpro and other cysteine proteases.

In Vivo Chemical Screening in Zebrafish Embryos Identified FDA-Approved Drugs That Induce Differentiation of Acute Myeloid Leukemia Cells.

Acute myeloid leukemia (AML) is characterized by the abnormal proliferation and differentiation arrest of myeloid progenitor cells. The clinical treatment of AML remains challenging. Promoting AML cell differentiation is a valid strategy, but effective differentiation drugs are lacking for most types of AML. In this study, we generated Tg(drl:hoxa9) zebrafish, in which hoxa9 overexpression was driven in hematopoietic cells and myeloid differentiation arrest was exhibited. Using Tg(drl:hoxa9) embryos, we performed chemical screening and identified four FDA-approved drugs, ethacrynic acid, khellin, oxcarbazepine, and alendronate, that efficiently restored myeloid differentiation. The four drugs also induced AML cell differentiation, with ethacrynic acid being the most effective. By an RNA-seq analysis, we found that during differentiation, ethacrynic acid activated the IL-17 and MAPK signaling pathways, which are known to promote granulopoiesis. Furthermore, we found that ethacrynic acid enhanced all-trans retinoic acid (ATRA)-induced differentiation, and both types of signaling converged on the IL-17/MAPK pathways. Inhibiting the IL-17/MAPK pathways impaired ethacrynic acid and ATRA-induced differentiation. In addition, we showed that ethacrynic acid is less toxic to embryogenesis and less disruptive to normal hematopoiesis than ATRA. Thus, the combination of ethacrynic acid and ATRA may have broader clinical applications. In conclusion, through zebrafish-aided screening, our study identified four drugs that can be repurposed to induce AML differentiation, thus providing new agents for AML therapy.

Dual approach: micellar delivery of chlorambucil prodrug with concurrent glutathione depletion and GST inhibition for enhanced anticancer activity

Although chlorambucil (CHL) is a long-established anticancer drug, the drug failure of CHL, mediated by the intracellular defense system consisting of glutathione (GSH) and GSH S-transferase pi (GST-pi), has significantly limited the application of CHL. To overcome this issue, we first designed a GSH-responsive small-molecule prodrug (EA-SS-CHL) by combining CHL and ethacrynic acid (EA). Subsequently, drug-loaded nanoparticles (ECPP) were formed by the self-assembly between EA-SS-CHL and amphiphilic PEG-PDLLA to improve the water solubility of the prodrug and its ability to target tumor sites. Upon exposure to high intracellular GSH concentration, EA-SS-CHL gradually degrades, leading to the release of EA and CHL. The presence of EA facilitates the depletion of GSH and inhibition of GST-pi, ultimately attenuating the detoxification of the intracellular defense system to CHL. Cytotoxicity studies and apoptosis assays demonstrate that ECPP exhibits higher therapeutic efficiency than CHL. Additionally, in vivo tumor suppression effects and biocompatibility provide further evidence for the superiority of ECPP. This work presents a promising strategy to enhance the efficacy of CHL in cancer therapy.

Molecular Cloning, Expression and Enzymatic Characterization of Tetrahymena thermophila Glutathione-S-Transferase Mu 34.

Glutathione-S-transferase enzymes (GSTs) are essential components of the phase II detoxification system and protect organisms from oxidative stress induced by xenobiotics and harmful toxins such as 1-chloro-2,4-dinitrobenzene (CDNB). In Tetrahymena thermophila, the TtGSTm34 gene was previously reported to be one of the most responsive GST genes to CDNB treatment (LD50 = 0.079mM). This study aimed to determine the kinetic features of recombinantly expressed and purified TtGSTm34 with CDNB and glutathione (GSH). TtGSTm34-8xHis was recombinantly produced in T. thermophila as a 25-kDa protein after the cloning of the 660-bp full-length ORF of TtGSTm34 into the pIGF-1 vector. A three-dimensional model of the TtGSTm34 protein constructed by the AlphaFold and PyMOL programs confirmed that it has structurally conserved and folded GST domains. The recombinant production of TtGSTm34-8xHis was confirmed by SDS‒PAGE and Western blot analysis. A dual-affinity chromatography strategy helped to purify TtGSTm34-8xHis approximately 3166-fold. The purified recombinant TtGSTm34-8xHis exhibited significantly high enzyme activity with CDNB (190µmol/min/mg) as substrate. Enzyme kinetic analysis revealed Km values of 0.68mM with GSH and 0.40mM with CDNB as substrates, confirming its expected high affinity for CDNB. The optimum pH and temperature were determined to be 7.0 and 25°C, respectively. Ethacrynic acid inhibited fully TtGSTm34-8xHis enzyme activity. These results imply that TtGSTm34 of T. thermophila plays a major role in the detoxification of xenobiotics, such as CDNB, as a first line of defense in aquatic protists against oxidative damage.

Essential oils work synergistically to mitigate pathogenic impact of Meloidogyne incognita, Rhizoctonia solani and Sclerotinia rolfsii

The phytochemical analysis and potential synergistic interactions between the essential oils (EOs) of Vitex negundo L. Piper longum L. and Vitex agnus-castus L. and their pesticidal efficacy were the main focus of this study. To examine their synergistic interactions with pesticidal activities, the recovered EOs were mixed in binary and ternary combinations at similar ratios and the nematicidal activity of individual EOs and their mixtures was evaluated. Using the disc-diffusion method, antifungal activity was evaluated. For comparison means of biological activities, a two-way ANOVA was carried out, at a significance level of 5% (p < 0.05). The main EO compounds were subjected to a molecular docking investigation to look into how they interacted with target proteins in comparison with standard inhibitors physostigmine (AChE), ethacrynic acid (GST-1), and hexaconazole (CYP51). The chemical compounds of EOs were identified via GC-MS analysis. Based on GC-MS analysis β-pinene, cis-nerolidol, 2-heptyl acetate, and α-pinene were the major compounds identified in PLAO; while in VACAO viridiflorol, β-caryophyllene, and 5-(1-isopropenyl-4,5-dimethyl bicyclo [4.3.0]nonan-5-yl)-3-methyl-2-pentenol acetate were detected as main components. Similarly, 1,8-cineole, (E)-β-ocimene, α-terpinyl acetate, and (Z)-β-ocimene were identified as major compounds in VACAO. When three EOs of P. longum, V. negundo, and V. agnus-castus were mixed, pesticidal activity results revealed a high synergy. These results validate synergistic interactions amongst the studied essential oils, which may support sustainable agriculture when applied as natural products against pathogens. The molecular docking results showed good binding affinities and attributed the strongest inhibitory activity to 5-(1-isopropenyl-4,5-dimethyl bicyclo [4.3.0]nonan-5-yl)-3-methyl-2-pentenol acetate for all the target proteins.

Design, Synthesis, Computational Studies, and Anti-Proliferative Evaluation of Novel Ethacrynic Acid Derivatives Containing Nitrogen Heterocycle, Urea, and Thiourea Moieties as Anticancer Agents.

In the present work, the synthesis of new ethacrynic acid (EA) derivatives containing nitrogen heterocyclic, urea, or thiourea moieties via efficient and practical synthetic procedures was reported. The synthesised compounds were screened for their anti-proliferative activity against two different cancer cell lines, namely, HL60 (promyelocytic leukaemia) and HCT116 (human colon carcinoma). The results of the in vitro tests reveal that compounds 1-3, 10, 16(a-c), and 17 exhibit potent anti-proliferative activity against the HL60 cell line, with values of the percentage of cell viability ranging from 20 to 35% at 1 μM of the drug and IC50 values between 2.37 μM and 0.86 μM. Compounds 2 and 10 showed a very interesting anti-proliferative activity of 28 and 48% at 1 μM, respectively, against HCT116. Two PyTAP-based fluorescent EA analogues were also synthesised and tested, showing good anti-proliferative activity. A test on the drug-likeness properties in silico of all the synthetised compounds was performed in order to understand the mechanism of action of the most active compounds. A molecular docking study was conducted on two human proteins, namely, glutathione S-transferase P1-1 (pdb:2GSS) and caspase-3 (pdb:4AU8) as target enzymes. The docking results show that compounds 2 and 3 exhibit significant binding modes with these enzymes. This finding provides a potential strategy towards developing anticancer agents, and most of the synthesised and newly designed compounds show good drug-like properties.

Pt(IV) Complexes in the Search for Novel Platinum Prodrugs with Promising Activity.

The kinetically inert, six coordinated, octahedral Pt(IV) complexes are termed dual-, triple-, or multi-action prodrugs based on the nature of the axially substituted ligands. These ligands are either inert or biologically active, where the nature of these axial ligands provides additional stability, synergistic biological activity or cell-targeting ability. There are many literature reports from each of these classes, mentioning the varied nature of these axial ligands. The ligands comprise drug molecules such as chlorambucil, doxorubicin, valproic acid, ethacrynic acid, biologically active chalcone, coumarin, combretastatin, non-steroidal anti-inflammatory drugs (NSAIDs) and many more, potentiating the anti-proliferative profile or reducing the side effects associated with cisplatin therapy. The targeting and non-targeting nature of these moieties exert additive or synergistic effects on the anti-cancer activity of Pt(II) moieties. Herein, we discuss the effects of these axially oriented ligands and the changes in the non-leaving am(m)ine groups and in the leaving groups on the biological activity. In this review, we have presented the latest developments in the field of Pt(IV) complexes that display promising activity with a reduced resistance profile. We have discussed the structure activity relationship (SAR) and the effects of the ligands on the biological activity of Pt(IV) complexes with cisplatin, oxaliplatin, carboplatin and the Pt core other than approved drugs. This literature work will help researchers to get an idea about Pt(IV) complexes that have been classified based on the aspects of their biological activity.

Association between GSTP1 I105V polymorphisms and responses to GSTP1 inhibitor treatment: in silico and in vitro insights

Glutathione S-transferase P1 (GSTP1) has gradually become a promising target for cancer prevention and treatment. However, subtle variations in GSTP1 can lead to the occurrence of single nucleotide polymorphisms (SNPs). The correlation between specific genotypes of GSTP1 and the clinical outcome of the disease has been extensively investigated, demonstrating a significant area of research in this field. However, their impact on the responses to GSTP1 inhibitor treatment remains to be elucidated. Among the various SNPs of GSTP1, I105V polymorphisms is the most widely studied. In this study, a silico model of GSTP1 I105V polymorphism was successfully established to predict the changes of binding model and binding affinity between GSTP1 I105(WT) or GSTP1 V105 and ethacrynic acid via molecular docking and molecular dynamics, and ultimately further evaluated for its anticancer effects. The result demonstrated that the binding capacity of ethacrynic acid decreases with the I105V mutation of GSTP1, indicating the changes in its anticancer activities. Cancer cells expressing GSTP1 V105 may exhibit greater tolerance to ethacrynic acid-induced toxicity compared to other genotypes. In summary, this study provides the first evidence that the GSTP1 I105V polymorphism may impact cancer cell sensitivity to its inhibitor through theoretical prediction. Furthermore, a comprehensive understanding of the correlation between GSTP1 I105V polymorphisms and responses to GSTP1 inhibitor treatment would offer valuable insights for future drug development targeting GSTP1 in cancer-related diseases. Communicated by Ramaswamy H. Sarma

Diuretic Strategies in Acute Decompensated Heart Failure: A Narrative Review.

Heart failure is a common condition with considerable associated costs, morbidity, and mortality. Patients often present to hospital with dyspnea and edema. Inadequate inpatient decongestion is an important contributor to high readmission rates. There is little evidence concerning diuresis to guide clinicians in caring for patients with acute decompensated heart failure. Contemporary diuretic strategies have been defined by expert opinion and older landmark clinical trials. To present a narrative review of contemporary recommendations, along with their underlying evidence and pharmacologic rationale, for diuretic strategies in inpatients with acute decompensated heart failure. PubMed, OVID, and Embase databases were searched from inception to December 22, 2022, with the following search terms: heart failure, acute heart failure, decompensated heart failure, furosemide, bumetanide, ethacrynic acid, hydrochlorothiazide, indapamide, metolazone, chlorthalidone, spironolactone, eplerenone, and acetazolamide. Randomized controlled trials and systematic reviews involving at least 100 adult patients (> 18 years) were included. Trials involving torsemide, chlorothiazide, and tolvaptan were excluded. Early, aggressive administration of a loop diuretic has been associated with expedited symptom resolution, shorter length of stay, and possibly reduced mortality. Guidelines make recommendations about dose and frequency but do not recommend any particular loop diuretic over another; however, furosemide is most commonly used. Guidelines recommend that the initial furosemide dose (on admission) be 2-2.5 times the patient's home dose. A satisfactory diuretic response can be defined as spot urine sodium content greater than 50-70 mmol/L at 2 hours; urine output greater than 100-150 mL/h in the first 6 hours or 3-5 L in 24 hours; or a change in weight of 0.5-1.5 kg in 24 hours. If congestion persists after the maximization of loop diuretic therapy over the first 24-48 hours, an adjunctive diuretic such as thiazide or acetazolamide should be added. If decongestion targets are not met, continuous infusion of furosemide may be considered. Heart failure with congestion can be managed with careful administration of high-dose loop diuretics, supported by thiazides and acetazolamide when necessary. Clinical trials are underway to further evaluate this strategy.

Oxidative stress-initiated one-carbon metabolism drives the generation of interleukin-10-producing B cells to resolve pneumonia.

The metabolic reprogramming underlying the generation of regulatory B cells during infectious diseases remains unknown. Using a Pseudomonas aeruginosa-induced pneumonia model, we reported that IL-10-producing B cells (IL-10+ B cells) play a key role in spontaneously resolving infection-mediated inflammation. Accumulated cytosolic reactive oxygen species (ROS) during inflammation were shown to drive IL-10+ B-cell generation by remodeling one-carbon metabolism. Depletion of the enzyme serine hydroxymethyltransferase 1 (Shmt1) led to inadequate one-carbon metabolism and decreased IL-10+ B-cell production. Furthermore, increased one-carbon flux elevated the levels of the methyl donor S-adenosylmethionine (SAM), altering histone H3 lysine 4 methylation (H3K4me) at the Il10 gene to promote chromatin accessibility and upregulate Il10 expression in B cells. Therefore, the one-carbon metabolism-associated compound ethacrynic acid (EA) was screened and found to potentially treat infectious pneumonia by boosting IL-10+ B-cell generation. Overall, these findings reveal that ROS serve as modulators to resolve inflammation by reprogramming one-carbon metabolism pathways in B cells.

Optimization of 3-Cyano-7-cyclopropylamino-pyrazolo[1,5-a]pyrimidines toward the Development of an In Vivo Chemical Probe for CSNK2A.

3-Cyano-7-cyclopropylamino-pyrazolo[1,5-a]pyrimidines, including the chemical probe SGC-CK2-1, are potent and selective inhibitors of CSNK2A in cells but have limited utility in animal models due to their poor pharmacokinetic properties. While developing analogues with reduced intrinsic clearance and the potential for sustained exposure in mice, we discovered that phase II conjugation by GST enzymes was a major metabolic transformation in hepatocytes. A protocol for codosing with ethacrynic acid, a covalent reversible GST inhibitor, was developed to improve the exposure of analogue 2h in mice. A double codosing protocol, using a combination of ethacrynic acid and irreversible P450 inhibitor 1-aminobenzotriazole, increased the blood level of 2h by 40-fold at a 5 h time point.

2(3H)-Dihydrofranolactone metabolites from Pleosporales sp. NUH322 as anti-amyotrophic lateral sclerosis drugs.

Amyotrophic lateral sclerosis (ALS) is a devastating motor disease with limited treatment options. A domestic fungal extract library was screened using three assays related to the pathophysiology of ALS with the aim of developing a novel ALS drug. 2(3H)-dihydrofuranolactones 1 and 2, and five known compounds3-7 were isolated from Pleosporales sp. NUH322 culture media, and their protective activity against the excitotoxicity of β-N-oxalyl-L-α,β-diaminopropionic acid (ODAP), an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamatergic agonist, was evaluated under low mitochondrial glutathione levels induced by ethacrynic acid (EA) and low sulfur amino acids using our developed ODAP-EA assay. Additional assays evaluated the recovery from cytotoxicity caused by transfected SOD1-G93A, an ALS-causal gene, and the inhibitory effect against reactive oxygen species (ROS) elevation. The structures of1 and 2were elucidated using various spectroscopic methods. We synthesized1 from D-ribose, and confirmed the absolute structure. Isolated and synthesized1displayed higher ODAP-EA activities than the extract and represented its activity. Furthermore,1exhibited protective activity against SOD1-G93A-induced toxicity. An ALS mouse model, SOD1-G93A, of both sexes, was treated orally with1at pre- and post-symptomatic stages. The latter treatment significantly extended their lifespan (p = 0.03) and delayed motor deterioration (p = 0.001-0.01). Our resultsuggests that1is a promising lead compound for the development of ALS drugs with a new spectrum of action targeting both SOD1-G93A proteopathy and excitotoxicity through its action on the AMPA-type glutamatergic receptor.

Functionalization of graphene oxide surfaces with phosphorus dendrimer and dendron

We report a novel approach for functionalizing the graphene oxide (GO) surface with AB5 phosphorus dendron, and dendrimer. First, a dendrimer was prepared having tyramine functions on the surface, while the AB5 dendrons were synthesized and characterized having either pyridine derivatives or ethacrynic acid terminal functions and a tyramine derivative linked to the core. Subsequently, these macromolecules were grafted onto the GO surface via covalent bonding. The resulting GO and modified-GO-AB5 dendron/dendrimer materials have been characterized by Fourier Transform Infrared (FTIR), Raman spectroscopy (RS), Thermogravimetric Analysis (TGA), Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) and Energy Dispersive X-ray spectroscopy (EDX) analyses. The dendritic structures and the functionalized materials were evaluated for their biological activity against HCT116 (human colon cancer), and against the non-cancerous RPE1 cells for the most active, to evaluate the safety.

A Switch-On Affinity-Based Iridium(III) Conjugate Probe for Imaging Mitochondrial Glutathione S-Transferase in Breast Cancer Cells.

Glutathione S-transferase is heterogeneously expressed in breast cancer cells and is therefore emerging as a potential diagnostic biomarker for studying the heterogeneity of breast cancers. However, available fluorescent probes for GSTs depend heavily on GSTs-catalyzed glutathione (GSH) nucleophilic substitution reactions, making them susceptible to interference by the high concentration of nucleophilic species in the cellular environment. Moreover, the functions of subcellular GSTs are generally overlooked due to the lack of suitable luminescence probes. Herein, we report a highly selective affinity-based luminescence probe 1 for GST in breast cancer cells through tethering a GST inhibitor, ethacrynic acid, to an iridium(III) complex. Compared to activity-based probes which require the use of GSH, this probe could image GST-pi in the mitochondria by directly adducting to GST-pi (or potentially GST-pi/GS) in living cells. Probe 1 possesses desirable photophysical properties including a lifetime of 911 ns, a Stokes shift of 343 nm, and high photostability. The "turn on" luminescence mode of the probe enables highly selective detection of the GST with a limit of detection of 1.01 μM, while its long emission lifetime allows sensitive detection in organic dye-spiked autofluorescence samples by a time-resolved mode. The probe was further applied to specifically and quantitatively visualize MDA-MB-231 cells via specific binding to mitochondrial GST, and could differentiate breast cell lines based on their expression levels of GST. To the best of our knowledge, this probe is the first affinity-based iridium(III) imaging probe for the subcellular GST. Our work provides a valuable tool for unmasking the diverse roles of a subcellular GST in living systems, as well as for studying the heterogeneity of breast cancers.

Busulfan induces steatosis in HepaRG cells but not in primary human hepatocytes: Possible explanations and implication for the prediction of drug-induced liver injury.

The antineoplastic drug busulfan can induce different hepatic lesions including cholestasis and sinusoidal obstruction syndrome. However, hepatic steatosis has never been reported in patients. This study aimed to determine whether busulfan could induce steatosis in primary human hepatocytes (PHH) and differentiated HepaRG cells. Neutral lipids were determined in PHH and HepaRG cells. Mechanistic investigations were performed in HepaRG cells by measuring metabolic fluxes linked to lipid homeostasis, reduced glutathione (GSH) levels, and expression of genes involved in lipid metabolism and endoplasmic reticulum (ER) stress. Analysis of two previous transcriptomic datasets was carried out. Busulfan induced lipid accumulation in HepaRG cells but not in six different batches of PHH. In HepaRG cells, busulfan impaired VLDL secretion, increased fatty acid uptake, and induced ER stress. Transcriptomic data analysis and decreased GSH levels suggested that busulfan-induced steatosis might be linked to the high expression of glutathione S-transferase (GST) isoenzyme A1, which is responsible for the formation of the hepatotoxic sulfonium cation conjugate. In keeping with this, the GST inhibitor ethacrynic acid and the chemical chaperone tauroursodeoxycholic acid alleviated busulfan-induced lipid accumulation in HepaRG cells supporting the role of the sulfonium cation conjugate and ER stress in steatosis. While the HepaRG cell line is an invaluable tool for pharmacotoxicological studies, it might not be always an appropriate model to predict and mechanistically investigate drug-induced liver injury. Hence, we recommend carrying out toxicological investigations in both HepaRG cells and PHH to avoid drawing wrong conclusions on the potential hepatotoxicity of drugs and other xenobiotics.