N-acetylcysteine, reactive oxygen species and beyond

Combined blockade of GPX4 and activated EGFR/HER3 bypass pathways inhibits the development of ALK-inhibitor-induced tolerant persister cells in ALK-fusion-positive lung cancer

Cancers can develop resistance to treatment with ALK tyrosine kinase inhibitors (ALK-TKIs) via emergence of a subpopulation of drug-tolerant persister (DTP) cells that can survive initial drug treatment long enough to acquire genetic aberrations. DTP cells are thus a potential therapeutic target. We generated alectinib-induced DTP cells from a patient-derived ALK+ non-small-cell lung cancer (NSCLC) cell line and screened 3114 agents in the anticancer compounds library (TargetMol). We identified phospholipid hydroperoxide glutathione peroxidase GPX4 as being involved in promoting the survival of DTP cells. GPX4 was found to be upregulated in DTP cells and to promote cell survival by suppressing reactive oxygen species (ROS) accumulation; GPX4 inhibitors blocked this upregulation and facilitated ROS-mediated cell death. Activated bypass signals involving epidermal growth factor receptor (EGFR)/receptor tyrosine-protein kinase erbB-3 (HER3) were also identified in DTP cells, and co-treatment with EGFR-TKI plus ALK-TKI enhanced ROS levels. Triple combination with an ALK-TKI plus a bypass pathway inhibitor plus a GPX4 inhibitor suppressed cell growth and induced intracellular ROS accumulation more greatly than did treatment with each agent alone. The combined inhibition of ALK plus inhibition of activated bypass signals plus inhibition of GPX4 may be a potent therapeutic strategy for patients with ALK+ NSCLC to prevent the development of resistance to ALK-TKIs and lead to tumor eradication.

Formation of multinucleated osteoclasts depends on an oxidized species of cell surface-associated La protein

The bone-resorbing activity of osteoclasts plays a critical role in the life-long remodeling of our bones that is perturbed in many bone loss diseases. Multinucleated osteoclasts are formed by the fusion of precursor cells, and larger cells - generated by an increased number of cell fusion events - have higher resorptive activity. We find that osteoclast fusion and bone resorption are promoted by reactive oxygen species (ROS) signaling and by an unconventional low molecular weight species of La protein, located at the osteoclast surface. Here, we develop the hypothesis that La's unique regulatory role in osteoclast multinucleation and function is controlled by an ROS switch in La trafficking. Using antibodies that recognize reduced or oxidized species of La, we find that differentiating osteoclasts enrich an oxidized species of La at the cell surface, which is distinct from the reduced La species conventionally localized within cell nuclei. ROS signaling triggers the shift from reduced to oxidized La species, its dephosphorylation and delivery to the surface of osteoclasts, where La promotes multinucleation and resorptive activity. Moreover, intracellular ROS signaling in differentiating osteoclasts oxidizes critical cysteine residues in the C-terminal half of La, producing this unconventional La species that promotes osteoclast fusion. Our findings suggest that redox signaling induces changes in the location and function of La and may represent a promising target for novel skeletal therapies.

Mitochondrial Dysfunction in Systemic Lupus Erythematosus: Insights and Therapeutic Potential

Systemic lupus erythematosus (SLE) is a complex autoimmune disorder characterized by the presence of various serum autoantibodies and multi-system effects, predominantly affecting young female patients. The pathogenesis of SLE involves a combination of genetic factors, environmental triggers, and pathogen invasions that disrupt immune cell activation, leading to the release of autoantibodies and chronic inflammation. Mitochondria, as the primary cellular powerhouses, play a crucial role in SLE development through their control of energy generation, reactive oxygen species (ROS) production, and cellular apoptotic pathways. Dysregulation of mitochondrial structure and function can contribute to the immune dysregulation, oxidative stress, and inflammation seen in SLE. Recent research has highlighted the impact of mitochondrial dysfunction on various immune cells involved in SLE pathogenesis, such as T-lymphocytes, B-lymphocytes, neutrophils, and plasmacytoid dendritic cells. Mitochondrial dysfunction in these immune cells leads to increased ROS production, disrupted mitophagy, and alterations in energy metabolism, contributing to immune dysregulation and inflammation. Moreover, genetic variations in mitochondrial DNA (mtDNA) and abnormalities in mitochondrial dynamics have been linked to the pathogenesis of SLE, exacerbating oxidative stress and immune abnormalities. Targeting mitochondrial function has emerged as a promising therapeutic approach for SLE. Drugs such as sirolimus, N-acetylcysteine, coenzyme Q10, and metformin have shown potential in restoring mitochondrial homeostasis, reducing oxidative stress, and modulating immune responses in SLE. These agents have demonstrated efficacy in preclinical models and clinical studies by improving disease activity, reducing autoantibody titers, and ameliorating organ damage in SLE patients. In conclusion, this review underscores the critical role of mitochondria in the pathogenesis of SLE and the potential of targeting mitochondrial dysfunction as a novel therapeutic strategy for improving outcomes in SLE patients. Further investigation into the mechanisms underlying mitochondrial involvement in SLE and the development of targeted mitochondrial therapies hold promise for advancing SLE treatment and enhancing patient care.

Enzymatic activity of HIV-1 protease defines migration of tumor cells in vitro and enhances their metastatic activity in vivo

Overexpression of aspartic proteases, as cathepsin D, is an independent marker of poor prognosis in breast cancer, correlated with the incidence of clinical metastasis. We aimed to find if HIV-1 aspartic protease (PR) can play a similar role. Murine adenocarcinoma 4T1luc2 cells were transduced with lentivirus encoding inactivated drug-resistant PR, generating subclones PR20.1 and PR20.2. Subclones were assessed for production of reactive oxygen species (ROS), expression of epithelial-mesenchymal transition (EMT) factors, and in vitro migratory activity in the presence or absence of antioxidant N-acetyl cysteine and protease inhibitors. Tumorigenic activity was evaluated by implanting cells into BALB/c mice and following tumor growth by calipering and bioluminescence imaging in vivo, and metastases, by organ imaging ex vivo. Both subclones expressed PR mRNA, and PR20.2, also the protein detected by Western blotting. PR did not induce production of ROS, and had no direct effect on cell migration rate, however, treatment with inhibitors of drug-resistant PR suppressed the migratory activity of both subclones. Furthermore, expression of N-cadherin and Vimentin in PR20.2 cells and their migration were enhanced by antioxidant treatment. Sensitivity of in vitro migration to protease inhibitors and to antioxidant, known to restore PR activity, related the effects to the enzymatic activity of PR. In vivo, PR20.2 cells demonstrated higher tumorigenic and metastatic activity than PR20.1 or parental cells. Thus, HIV-1 protease expressed in breast cancer cells determines their migration in vitro and metastatic activity in vivo. This effect may aggravate clinical course of cancers in people living with HIV-1.

Dielectrophoretic characterization of peroxidized retinal pigment epithelial cells as a model of age-related macular degeneration

BACKGROUND

Age-related macular degeneration (AMD) is a prevalent ocular pathology affecting mostly the elderly population. AMD is characterized by a progressive retinal pigment epithelial (RPE) cell degeneration, mainly caused by an impaired antioxidative defense. One of the AMD therapeutic procedures involves injecting healthy RPE cells into the subretinal space, necessitating pure, healthy RPE cell suspensions. This study aims to electrically characterize RPE cells to demonstrate a possibility using simulations to separate healthy RPE cells from a mixture of healthy/oxidized cells by dielectrophoresis.

METHODS

BPEI-1 rat RPE cells were exposed to hydrogen peroxide to create an in-vitro AMD cellular model. Cell viability was evaluated using various methods, including microscopic imaging, impedance-based real-time cell analysis, and the MTS assay. Healthy and oxidized cells were characterized by recording their dielectrophoretic spectra, and electric cell parameters (crossover frequency, membrane conductivity and permittivity, and cytoplasm conductivity) were computed. A COMSOL simulation was performed on a theoretical microfluidic-based dielectrophoretic separation chip using these parameters.

RESULTS

Increasing the hydrogen peroxide concentration shifted the first crossover frequency toward lower values, and the cell membrane permittivity progressively increased. These changes were attributed to progressive membrane peroxidation, as they were diminished when measured on cells treated with the antioxidant N-acetylcysteine. The changes in the crossover frequency were sufficient for the efficient separation of healthy cells, as demonstrated by simulations.

CONCLUSIONS

The study demonstrates that dielectrophoresis can be used to separate healthy RPE cells from oxidized ones based on their electrical properties. This method could be a viable approach for obtaining pure, healthy RPE cell suspensions for AMD therapeutic procedures.

Protective effect of N-acetylcysteine against hepatocellular carcinoma in hepatitis B virus carriers

Hepatitis B virus (HBV) infection is a leading risk factor for hepatocellular carcinoma (HCC), contributing to cancer development through direct genomic integration and chronic inflammation. N-acetylcysteine (NAC), known for its antioxidant properties, is widely utilized in cancer prevention. However, clinical evidence regarding its protective effect against HCC in HBV carriers remains sparse. In this retrospective cohort study spanning 2008 to 2018, we utilized Taiwan's National Health Insurance Research Database (NHIRD) to include 1,061,174 chronic HBV carriers. Participants were stratified into NAC users and non-users using Propensity Score Matching. We assessed the incidence of HCC in both cohorts, examining the relationship between NAC usage duration and HCC incidence, and evaluating the dose-response effect. NAC users exhibited a significantly lower risk of developing HCC (adjusted hazard ratio [aHR]: 0.38; 95% confidence interval [CI]: 0.36-0.40; P < 0.0001). A dose-response relationship was evident, with higher cumulative defined daily doses (cDDDs) of NAC correlating with reduced HCC risk, revealing a significant trend (P < 0.0001). Notably, a daily NAC intensity of > 1.4 DDDs was associated with a decreased risk of HCC in HBV patients. Our results demonstrate that the use of NAC, in a dose-dependent manner, is intricately linked with a diminished incidence of HCC in individuals chronically infected with the HBV.

Acod1-mediated inhibition of aerobic glycolysis suppresses osteoclast differentiation and attenuates bone erosion in arthritis

OBJECTIVES

Metabolic changes are crucially involved in osteoclast development and may contribute to bone degradation in rheumatoid arthritis (RA). The enzyme aconitate decarboxylase 1 (Acod1) is known to link the cellular function of monocyte-derived macrophages to their metabolic status. As osteoclasts derive from the monocyte lineage, we hypothesised a role for Acod1 and its metabolite itaconate in osteoclast differentiation and arthritis-associated bone loss.

METHODS

Itaconate levels were measured in human peripheral blood mononuclear cells (PBMCs) of patients with RA and healthy controls by mass spectrometry. Human and murine osteoclasts were treated with the itaconate derivative 4-octyl-itaconate (4-OI) in vitro. We examined the impact of Acod1-deficiency and 4-OI treatment on bone erosion in mice using K/BxN serum-induced arthritis and human TNF transgenic (hTNFtg) mice. SCENITH and extracellular flux analyses were used to evaluate the metabolic activity of osteoclasts and osteoclast progenitors. Acod1-dependent and itaconate-dependent changes in the osteoclast transcriptome were identified by RNA sequencing. CRISPR/Cas9 gene editing was used to investigate the role of hypoxia-inducible factor (Hif)-1α in Acod1-mediated regulation of osteoclast development.

RESULTS

Itaconate levels in PBMCs from patients with RA were inversely correlated with disease activity. Acod1-deficient mice exhibited increased osteoclast numbers and bone erosion in experimental arthritis while 4-OI treatment alleviated inflammatory bone loss in vivo and inhibited human and murine osteoclast differentiation in vitro. Mechanistically, Acod1 suppressed osteoclast differentiation by inhibiting succinate dehydrogenase-dependent production of reactive oxygen species and Hif1α-mediated induction of aerobic glycolysis.

CONCLUSION

Acod1 and itaconate are crucial regulators of osteoclast differentiation and bone loss in inflammatory arthritis.

FORMATION OF MULTINUCLEATED OSTEOCLASTS DEPENDS ON AN OXIDIZED SPECIES OF CELL SURFACE ASSOCIATED LA PROTEIN

The bone-resorbing activity of osteoclasts plays a critical role in the life-long remodeling of our bones that is perturbed in many bone loss diseases. Multinucleated osteoclasts are formed by the fusion of precursor cells, and larger cells - generated by an increased number of cell fusion events - have higher resorptive activity. We find that osteoclast fusion and bone-resorption are promoted by reactive oxygen species (ROS) signaling and by an unconventional low molecular weight species of La protein, located at the osteoclast surface. Here, we develop the hypothesis that La's unique regulatory role in osteoclast multinucleation and function is controlled by a ROS switch in La trafficking. Using antibodies that recognize reduced or oxidized species of La, we find that differentiating osteoclasts enrich an oxidized species of La at the cell surface, which is distinct from the reduced La species conventionally localized within cell nuclei. ROS signaling triggers the shift from reduced to oxidized La species, its dephosphorylation and delivery to the surface of osteoclasts, where La promotes multinucleation and resorptive activity. Moreover, intracellular ROS signaling in differentiating osteoclasts oxidizes critical cysteine residues in the C-terminal half of La, producing this unconventional La species that promotes osteoclast fusion. Our findings suggest that redox signaling induces changes in the location and function of La and may represent a promising target for novel skeletal therapies.

Chlorobenzoquinones Aggravate RSL3-Induced Ferroptosis in ROS-Dependent Manner

Chlorobenzoquinones (CBQs) are a class of emerging water disinfection byproducts that pose significant risks to public health. In this study, we found that three CBQs (tetrachloro-1,4-benzoquinone, 2,5-dichloro-1,4-benzoquinone, and 2-chloro-1,4-benzoquinone) can significantly aggravate cell death caused by Ras-selective lethal small molecule 3 (RSL3). Further study showed that the cell death caused by CBQs, either alone or in combination with RSL3, was related to iron accumulation and GPX4 inactivation, suggesting the occurrence of ferroptosis. Furthermore, reactive oxygen species are found to play a potential key role in mediating the toxicity of CBQs in CBQs and RSL3-induced ferroptosis. These findings will be helpful in understanding the toxic mechanism of CBQs to mammalian cells.

Investigating the impact of Psidium guajava leaf hydroalcoholic extract in improving glutamatergic toxicity-induced oxidative stress in Danio rerio larvae

Glutamate is one of the predominant excitatory neurotransmitters released from the central nervous system; however, at high concentrations, this substance may induce excitotoxicity. This phenomenon is involved in numerous neuropathologies. At present, clinically available pharmacotherapeutic agents to counteract glutamatergic excitotoxicity are not completely effective; therefore, research to develop novel compounds is necessary. In this study, the main objective was to determine the pharmacotherapeutic potential of the hydroalcoholic extract of Psidium guajava (PG) in a model of oxidative stress-induced by exposure to glutamate utilizing Danio rerio larvae (zebrafish) as a model. Data showed that treatment with glutamate produced a significant increase in oxidative stress, chromatin damage, apoptosis, and locomotor dysfunction. All these effects were attenuated by pre-treatment with the classical antioxidant N-acetylcysteine (NAC). Treatment with PG inhibited oxidative stress responsible for cellular damage induced by glutamate. However, exposure to PG failed to prevent glutamate-initiated locomotor damage. Our findings suggest that under conditions of oxidative stress, PG can be considered as a promising candidate for treatment of glutamatergic excitotoxicity and consequent neurodegenerative diseases.

Glycolytic enzymes in non-glycolytic web: functional analysis of the key players

To survive in the tumour microenvironment, cancer cells undergo rapid metabolic reprograming and adaptability. One of the key characteristics of cancer is increased glycolytic selectivity and decreased oxidative phosphorylation (OXPHOS). Apart from ATP synthesis, glycolysis is also responsible for NADH regeneration and macromolecular biosynthesis, such as amino acid biosynthesis and nucleotide biosynthesis. This allows cancer cells to survive and proliferate even in low-nutrient and oxygen conditions, making glycolytic enzymes a promising target for various anti-cancer agents. Oncogenic activation is also caused by the uncontrolled production and activity of glycolytic enzymes. Nevertheless, in addition to conventional glycolytic processes, some glycolytic enzymes are involved in non-canonical functions such as transcriptional regulation, autophagy, epigenetic changes, inflammation, various signaling cascades, redox regulation, oxidative stress, obesity and fatty acid metabolism, diabetes and neurodegenerative disorders, and hypoxia. The mechanisms underlying the non-canonical glycolytic enzyme activities are still not comprehensive. This review summarizes the current findings on the mechanisms fundamental to the non-glycolytic actions of glycolytic enzymes and their intermediates in maintaining the tumor microenvironment.

Targeting the Multiple Complex Processes of Hypoxia-Ischemia to Achieve Neuroprotection

Hypoxic-ischemic encephalopathy (HIE) is a major cause of newborn brain damage stemming from a lack of oxygenated blood flow in the neonatal period. Twenty-five to fifty percent of asphyxiated infants who develop HIE die in the neonatal period, and about sixty percent of survivors develop long-term neurological disabilities. From the first minutes to months after the injury, a cascade of events occurs, leading to blood-brain barrier (BBB) opening, neuronal death and inflammation. To date, the only approach proposed in some cases is therapeutic hypothermia (TH). Unfortunately, TH is only partially protective and is not applicable to all neonates. This review synthesizes current knowledge on the basic molecular mechanisms of brain damage in hypoxia-ischemia (HI) and on the different therapeutic strategies in HI that have been used and explores a major limitation of unsuccessful therapeutic approaches.

Cytokine CCL9 Mediates Oncogenic KRAS-Induced Pancreatic Acinar-to-Ductal Metaplasia by Promoting Reactive Oxygen Species and Metalloproteinases

Pancreatic ductal adenocarcinoma (PDAC) can originate from acinar-to-ductal metaplasia (ADM). Pancreatic acini harboring oncogenic Kras mutations are transdifferentiated to a duct-like phenotype that further progresses to become pancreatic intraepithelial neoplasia (PanIN) lesions, giving rise to PDAC. Although ADM formation is frequently observed in KrasG12D transgenic mouse models of PDAC, the exact mechanisms of how oncogenic KrasG12D regulates this process remain an enigma. Herein, we revealed a new downstream target of oncogenic Kras, cytokine CCL9, during ADM formation. Higher levels of CCL9 and its receptors, CCR1 and CCR3, were detected in ADM regions of the pancreas in p48cre:KrasG12D mice and human PDAC patients. Knockdown of CCL9 in KrasG12D-expressed pancreatic acini reduced KrasG12D-induced ADM in a 3D organoid culture system. Moreover, exogenously added recombinant CCL9 and overexpression of CCL9 in primary pancreatic acini induced pancreatic ADM. We also showed that, functioning as a downstream target of KrasG12D, CCL9 promoted pancreatic ADM through upregulation of the intracellular levels of reactive oxygen species (ROS) and metalloproteinases (MMPs), including MMP14, MMP3 and MMP2. Blockade of MMPs via its generic inhibitor GM6001 or knockdown of specific MMP such as MMP14 and MMP3 decreased CCL9-induced pancreatic ADM. In p48cre:KrasG12D transgenic mice, blockade of CCL9 through its specific neutralizing antibody attenuated pancreatic ADM structures and PanIN lesion formation. Furthermore, it also diminished infiltrating macrophages and expression of MMP14, MMP3 and MMP2 in the ADM areas. Altogether, our results provide novel mechanistic insight into how oncogenic Kras enhances pancreatic ADM through its new downstream target molecule, CCL9, to initiate PDAC.

Eight weeks of treatment with mineralocorticoid receptor blockade does not alter vascular function in individuals with and without type 2 diabetes

Aldosterone has been suggested to be involved in the microvascular complications observed in type 2 diabetes. We aimed to investigate the effect of mineralocorticoid receptor (MR) blockade on endothelial function in individuals with type 2 diabetes compared to healthy controls. We included 12 participants with type 2 diabetes and 14 controls. We measured leg hemodynamics at baseline and during femoral arterial infusion of acetylcholine and sodium nitroprusside before and 8 weeks into treatment with MR blockade (eplerenone). Acetylcholine infusion was repeated with concomitant n-acetylcysteine (antioxidant) infusion. No difference in leg blood flow or vascular conductance was detected before or after the treatment with MR blockade in both groups and there was no difference between groups. Infusion of n-acetylcysteine increased baseline blood flow and vascular conductance, but did not change the vascular response to acetylcholine before or after treatment with MR blockade. Skeletal muscle eNOS content was unaltered by MR blockade and no difference between groups was detected. In conclusion, we found no effect of MR blockade endothelial function in individuals with and without type 2 diabetes. As the individuals with type 2 diabetes did not have vascular dysfunction, these results might not apply to individuals with vascular dysfunction.

Sustained PGC-1α2 or PGC-1α3 expression induces astrocyte dysfunction and degeneration

Peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) transcriptional coactivators are key regulators of energy metabolism-related genes and are expressed in energy-demanding tissues. There are several PGC-1α variants with different biological functions in different tissues. The brain is one of the tissues where the role of PGC-1α isoforms remains less explored. Here, we used a toxin-based mouse model of Parkinson's disease (PD) and observed that the expression levels of variants PGC-1α2 and PGC-1α3 in the nigrostriatal pathway increases at the onset of dopaminergic cell degeneration. This increase occurs concomitant with an increase in glial fibrillary acidic protein levels. Since PGC-1α coactivators regulate cellular adaptive responses, we hypothesized that they could be involved in the modulation of astrogliosis induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Therefore, we analysed the transcriptome of astrocytes transduced with expression vectors encoding PGC-1α1 to 1α4 by massively parallel sequencing (RNA-seq) and identified the main cellular pathways controlled by these isoforms. Interestingly, in reactive astrocytes the inflammatory and antioxidant responses, adhesion, migration, and viability were altered by PGC-1α2 and PGC-1α3, showing that sustained expression of these isoforms induces astrocyte dysfunction and degeneration. This work highlights PGC-1α isoforms as modulators of astrocyte reactivity and as potential therapeutic targets for the treatment of PD and other neurodegenerative disorders.

Cadmium neurotoxicity and therapeutic strategies

Cadmium (Cd) is a multitarget, carcinogenic, nonessential environmental pollutant. Due to its toxic effects at very low concentrations, lengthy biological half-life, and low excretion rate, exposure to Cd carries a concern. Prolonged exposure to Cd causes severe injury to the nervous system of both humans and animals. Nevertheless, the precise mechanisms responsible for the neurotoxic effects of Cd have yet to be fully elucidated. The accurate chemical mechanism potentially entails the destruction of metal-ion homeostasis, inducing oxidative stress, apoptosis, and autophagy. Here we review the evidence of the neurotoxic effects of Cd and corresponding strategies to protect against Cd-induced central nervous system injury.

Phenethyl isothiocyanate and irinotecan synergistically induce cell apoptosis in colon cancer HCT 116 cells in vitro

Irinotecan (IRI), an anticancer drug to treat colon cancer patients, causes cytotoxic effects on normal cells. Phenethyl isothiocyanate (PEITC), rich in common cruciferous plants, has anticancer activities (induction of cell apoptosis) in many human cancer cells, including colon cancer cells. However, the anticancer effects of IRI combined with PEITC on human colon cancer cells in vitro were unavailable. Herein, the aim of this study is to focus on the apoptotic effects of the combination of IRI and PEITC on human colon cancer HCT 116 cells in vitro. Propidium iodide (PI) exclusion and Annexin V/PI staining assays showed that IRI combined with PEITC decreased viable cell number and induced higher cell apoptosis than that of IRI or PEITC only in HCT 116 cells. Moreover, combined treatment induced higher levels of reactive oxygen species (ROS) and Ca2+ than that of IRI or PEITC only. Cells pre-treated with N-acetyl-l-cysteine (scavenger of ROS) and then treated with IRI, PEITC, or IRI combined with PEITC showed increased viable cell numbers than that of IRI or PEITC only. IRI combined with PEITC increased higher caspase-3, -8, and -9 activities than that of IRI or PEITC only by flow cytometer assay. IRI combined with PEITC induced higher levels of ER stress-, mitochondria-, and caspase-associated proteins than that of IRI or PEITC treatment only in HCT 116 cells. Based on these observations, PEITC potentiates IRI anticancer activity by promoting cell apoptosis in the human colon HCT 116 cells. Thus, PEITC may be a potential enhancer for IRI in humans as an anticolon cancer drug in the future.

Unraveling the mechanistic insights of sophorolipid-capped gold nanoparticle-induced cell death in Vibrio cholerae

IMPORTANCE

Vibrio cholerae, a Gram-negative bacterium, is the causative agent of a fatal disease, "cholera." Prevention of cholera outbreak is possible by eliminating the bacteria from the environment. However, antimicrobial resistance developed in microorganisms has posed a threat and challenges to its treatment. Application of nanoparticles is a useful and effective option for the elimination of such microorganisms. Metal-based nanopaticles exhibit microbial toxicity through non-specific mechanisms. To prevent resistance development and increase antibacterial efficiency, rational designing of nanoparticles is required. Thus, knowledge on the exact mechanism of action of nanoparticles is highly essential. In this study, we explore the possible mechanisms of antibacterial activity of AuNPs-SL against V. cholerae. We show that the interaction of AuNPs-SL with V. cholerae enhances ROS production and membrane depolarization, change in permeability, and leakage of intracellular content. This action leads to the depletion of cellular ATP level, DNA damage, and subsequent cell death.

When nitrosative stress hits the endoplasmic reticulum: Possible implications in oxLDL/oxysterols-induced endothelial dysfunction

Oxidized LDL (oxLDL) and oxysterols are known to play a crucial role in endothelial dysfunction (ED) by inducing endoplasmic reticulum stress (ERS), inflammation, and apoptosis. However, the precise molecular mechanisms underlying these pathophysiological processes remain incompletely understood. Emerging evidence strongly implicates excessive nitric oxide (NO) production in the progression of various pathological conditions. The accumulation of reactive nitrogen species (RNS) leading to nitrosative stress (NSS) and aberrant protein S-nitrosylation contribute to NO toxicity. Studies have highlighted the involvement of NSS and S-nitrosylation in perturbing ER signaling through the modification of ER sensors and resident isomerases in neurons. This review focuses on the existing evidence that strongly associates NO with ERS and the possible implications in the context of ED induced by oxLDL and oxysterols. The potential effects of perturbed NO synthesis on signaling effectors linking NSS with ERS in endothelial cells are discussed to provide a conceptual framework for further investigations and the development of novel therapeutic strategies targeting ED.

Oxidative stress mediates the inhibitory effects of Manzamine A on uterine leiomyoma cell proliferation and extracellular matrix deposition via SOAT inhibition

Uterine fibroids, the most common benign tumors of the myometrium in women, are characterized by abnormal extracellular matrix deposition and uterine smooth muscle cell neoplasia, with high recurrence rates. Here, we investigated the potential of the marine natural product manzamine A (Manz A), which has potent anti-cancer effects, as a treatment for uterine fibroids. Manz A inhibited leiomyoma cell proliferation in vitro and in vivo by arresting cell cycle progression and inducing caspase-mediated apoptosis. We performed target prediction analysis and identified sterol o-acyltransferases (SOATs) as potential targets of Manz A. Cholesterol esterification and lipid droplet formation were reduced by Manz A, in line with reduced SOAT expression. As a downstream target of SOAT, Manz A also prevented extracellular matrix deposition by inhibiting the β-catenin/fibronectin/metalloproteinases axis and enhanced autophagy turnover. Excessive free fatty acid accumulation by SOAT inhibition led to reactive oxygen species to impair mitochondrial oxidative phosphorylation and trigger endoplasmic reticulum stress via PERK/eIF2α/CHOP signaling. The inhibitory effect of ManzA on cell proliferation was partially restored by PERK knockdown and eliminated by tauroursodeoxycholic acid, suggesting oxidative stress plays a critical role in the mechanism of action of Manz A. These findings suggest that targeting SOATs by Manz A may be a promising therapeutic approach for uterine fibroids.

Manoalide Induces Intrinsic Apoptosis by Oxidative Stress and Mitochondrial Dysfunction in Human Osteosarcoma Cells

Osteosarcoma (OS) is the most common primary malignant bone tumor that produces immature osteoid. Metastatic OS has a poor prognosis with a death rate of >70%. Manoalide is a natural sesterterpenoid isolated from marine sponges. It is a phospholipase A2 inhibitor with anti-inflammatory, analgesic, and anti-cancer properties. This study aimed to investigate the mechanism and effect of manoalide on OS cells. Our experiments showed that manoalide induced cytotoxicity in 143B and MG63 cells (human osteosarcoma). Treatment with manoalide at concentrations of 10, 20, and 40 µM for 24 and 48 h reduced MG63 cell viability to 45.13-4.40% (p < 0.01). Meanwhile, manoalide caused reactive oxygen species (ROS) overproduction and disrupted antioxidant proteins, activating the apoptotic proteins caspase-9/-3 and PARP (Poly (ADP-ribose) polymerase). Excessive levels of ROS in the mitochondria affected oxidative phosphorylation, ATP generation, and membrane potential (ΔΨ_m). Additionally, manoalide down-regulated mitochondrial fusion protein and up-regulated mitochondrial fission protein, resulting in mitochondrial fragmentation and impaired function. On the contrary, a pre-treatment with n-acetyl-l-cysteine ameliorated manoalide-induced apoptosis, ROS, and antioxidant proteins in OS cells. Overall, our findings show that manoalide induces oxidative stress, mitochondrial dysfunction, and apoptosis, causing the cell death of OS cells, showing potential as an innovative alternative treatment in human OS.

Hydrogen Attenuates Inflammation by Inducing Early M2 Macrophage Polarization in Skin Wound Healing

The heterogeneous and highly plastic cell populations of macrophages are important mediators of cellular responses during all stages of wound healing, especially in the inflammatory stage. Molecular hydrogen (H₂), which has potent antioxidant and anti-inflammatory effects, has been shown to promote M2 polarization in injury and disease. However, more in vivo time series studies of the role of M1-to-M2 polarization in wound healing are needed. In the current study, we performed time series experiments on a dorsal full-thickness skin defect mouse model in the inflammatory stage to examine the effects of H₂ inhalation. Our results revealed that H₂ could promote very early M1-to-M2 polarization (on days 2-3 post wounding, 2-3 days earlier than in conventional wound healing), without disturbing the functions of the M1 phenotype. Time series analysis of the transcriptome, blood cell counts, and multiple cytokines further indicated that peripheral blood monocytes were a source of H₂-induced M2 macrophages and that the functions of H₂ in macrophage polarization were not only dependent on its antioxidant effects. Therefore, we believe that H₂ could reduce inflammation in wound care by shifting early macrophage polarization in clinical settings.

Expected and Unexpected Effects of Pharmacological Antioxidants

In this review, we have collected the existing data on the bioactivity of antioxidants (N-acetylcysteine, polyphenols, vitamin C) which are traditionally used in experimental biology and, in some cases, in the clinic. Presented data show that, despite the capacity of these substances to scavenge peroxides and free radicals in cell-free systems, their ability to exhibit these properties in vivo, upon pharmacological supplementation, has not been confirmed so far. Their cytoprotective activity is explained mainly by the ability not to suppress, but to activate multiple redox pathways, which causes biphasic hormetic responses and highly pleiotropic effects in cells. N-acetylcysteine, polyphenols, and vitamin C affect redox homeostasis by generating low-molecular-weight redox-active compounds (H₂O₂ or H₂S), known for their ability to stimulate cellular endogenous antioxidant defense and promote cytoprotection at low concentrations but exert deleterious effects at high concentrations. Moreover, the activity of antioxidants strongly depends on the biological context and mode of their application. We show here that considering the biphasic and context-dependent response of cells on the pleiotropic action of antioxidants can help explain many of the conflicting results obtained in basic and applied research and build a more logical strategy for their use.

Oxathiazinane derivatives display both antineoplastic and antibacterial activity: a structure activity study

PURPOSE

The Oxathiazinane substance class is characterized by a high diversity of chemical structures yet to be fully investigated. Our research group recently proved that the 1.4.5-oxathiazine-4.4-dioxide, known as substance GP-2250, possesses antineoplastic properties as shown on pancreatic carcinoma. This current study aims to gain insights into the structure and activity relationship of a series of different Oxathiazinanes regarding their antineoplastic activity and the potential correlation with antibacterial activity. We investigated the newly synthesized Oxathiazinane derivatives: 2255, 2256, 2287, 2289, 2293 and 2296 in comparison to GP-2250.

METHODS

The antineoplastic effect was evaluated in different cancer entities (breast, skin, pancreas and colon cancer cell lines) by viability, proliferation, and cell migration assays in vitro. Disc diffusion tests were performed on various bacteria strains to examine the antibacterial potential. Additionally, reactive oxygen species (ROS) assays were conducted to investigate mechanistic aspects.

RESULTS

The substances GP-2250, 2293, 2289 and 2296 not only showed antineoplastic activity in four different cancer entities but also antibacterial effects, as tested on multiple bacteria strains including MRSA (Methicillin-resistant Staphylococcus aureus). Furthermore, these substances also induced high ROS levels up to 110% in the treated cancer cell lines compared to untreated control cells. These results indicate a correlation between an antineoplastic capacity and antibacterial properties of these derivatives. Both activities appear to be ROS driven. The Oxathiazinane derivatives 2255, 2256 and 2287 lacked both, antineoplastic and antibacterial activity.

CONCLUSION

Thus, a comparable structure activity relationship became apparent for both the antineoplastic and antibacterial activity.

Lysosome directed red light photodynamic therapy using glycosylated iron-(III) conjugates of boron-dipyrromethene

To overcome the drawbacks associated with chemotherapeutic and porphyrin-based photodynamic therapy (PDT) agents, the use of BODIPY (boron-dipyrromethene) scaffold has gained prominence in designing a new generation of photosensitizers-cum-cellular imaging agents. However, their poor cell permeability and limited solubility in aqueous medium inhibits the in-vitro application of their organic form. This necessitates the development of metal-BODIPY conjugates with improved physiological stability and enhanced therapeutic efficacy. We have designed two iron(III)-BODIPY conjugates, [Fe(L^1/2)(L³)Cl] derived from benzyl-dipicolylamine and its glycosylated analogue along with a BODIPY-tagged catecholate. The complexes showed intense absorption bands (ε ∼ 55,000 M^-1 cm^-1) and demonstrated apoptotic PDT activity upon red-light irradiation (30 J/cm², 600-720 nm). The complex with singlet oxygen quantum yield value of ∼0.34 gave sub-micromolar IC₅₀ (half-maximal inhibitory concentration) value (∼0.08 μM) in both HeLa and H1299 cancer cells with a photocytotoxicity index value of >1200. Both the complexes were found to have significantly lower cytotoxic effects in non-cancerous HPL1D (human peripheral lung epithelial) cells. Singlet oxygen was determined to be the prime reactive oxygen species (ROS) responsible for cell damage from pUC19 DNA photo-cleavage studies, 1,3-diphenylisobenzofuran and SOSG (Singlet Oxygen Sensor Green) assays. Cellular imaging studies showed excellent fluorescence from complex 2 within 4 h, with localization in lysosomes. Significant drug accumulation into the core of 3D multicellular tumor spheroids was observed within 8 h from intense in-vitro emission. The complexes exemplify iron-based targeted PDT agents and show promising results as potential transition metal-based drugs for ROS mediated red light photocytotoxicity with low dosage requirement.

Gasdermin D membrane pores orchestrate IL-1α secretion from necrotic macrophages after NFS-rich silica exposure

IL-1α is an intracellular danger signal (DAMP) released by macrophages contributing to the development of silica-induced lung inflammation. The exact molecular mechanism orchestrating IL-1α extracellular release from particle-exposed macrophages is still unclear. To delineate this process, murine J774 and bone-marrow derived macrophages were exposed to increasing concentrations (1-40 cm2/ml) of a set of amorphous and crystalline silica particles with different surface chemical features. In particular, these characteristics include the content of nearly free silanols (NFS), a silanol population responsible for silica cytotoxicity recently identified. We first observed de novo stocks of IL-1α in macrophages after silica internalization regardless of particle physico-chemical characteristics and cell stress. IL-1α intracellular production and accumulation were observed by exposing macrophages to biologically-inert or cytotoxic crystalline and amorphous silicas. In contrast, only NFS-rich reactive silica particles triggered IL-1α release into the extracellular milieu from necrotic macrophages. We demonstrate that IL-1α is actively secreted through the formation of gasdermin D (GSDMD) pores in the plasma membrane and not passively released after macrophage plasma membrane lysis. Our findings indicate that the GSDMD pore-dependent secretion of IL-1α stock from macrophages solely depends on cytotoxicity induced by NFS-rich silica. This new regulated process represents a key first event in the mechanism of silica toxicity, suitable to refine the existing adverse outcome pathway (AOP) for predicting the inflammatory activity of silicas.

Folpet promotes apoptosis of bovine mammary epithelial cells via disruption of redox homeostasis and activation of MAPK cascades

Folpet, a phthalimide fungicide, is an agrochemical used to prevent fungal diseases in several crops. The toxicity of folpet has been demonstrated in Cyprinus carpio, pigs, and the human respiratory system. However, despite the possibilities of ingestion of folpet through feed, detrimental influences of folpet on dairy cattle have not been documented. Thus, this study aimed to record the harmful effects of folpet on the bovine mammary system and milk production using mammary epithelial cells (MAC-T cells), which play an essential role in the maintenance of yield and quality of milk production. In this study, we first confirmed that folpet exhibited cytotoxicity against MAC-T cells in both 2D and 3D cultures. Folpet treatment caused apoptosis, dysregulated intracellular calcium levels, and mitochondrial membrane potential, leading to cell death. We further demonstrated the induction of oxidative stress upon folpet treatment by assessing reactive oxygen species (ROS) content and lipid peroxidation in MAC-T cells. ROS generation following folpet treatment induced activation of MAPK cascades, including ERK1/2, JNK, and p38 signaling. This is the first report highlighting the detrimental impacts of folpet on bovine mammary glands and, consequently, the dairy industry by elucidating intracellular mechanisms using MAC-T cells.

Surfactin induces autophagy, apoptosis, and cell cycle arrest in human oral squamous cell carcinoma

OBJECTIVES

To investigate the anticancer effects and underlying mechanisms of surfactin on human oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

The capacity of surfactin to induce apoptosis, autophagy, and cell cycle arrest of two different human OSCC cell lines was investigated by cell viability, acridine orange staining, and cell cycle regulatory protein expression, respectively. The signaling network underlying these processes were determined by the analysis of reactive oxygen species (ROS) generation, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, endoplasmic reticulum (ER) stress-related protein levels, calcium release, mitogen-activated protein kinases activation, and cell cycle regulatory protein expression through corresponding reagents and experiments under various experimental conditions using specific pharmaceutical inhibitors or small interfering RNAs.

RESULTS

Surfactin was able to induce apoptosis through NADPH oxidase/ROS/ER stress/calcium-downregulated extracellular signal-regulated kinases 1/2 pathway. Surfactin could also lead to autophagy that shared the common regulatory signals with apoptosis pathway until calcium node. Cell cycle arrest at G₂ /M phase caused by surfactin was demonstrated through p53 and p21 accumulation combined p34^cdc2 , phosphorylated p34^cdc2 , and cyclin B1 inhibition, which was regulated by NADPH oxidase-derived ROS.

CONCLUSION

Surfactin could induce apoptosis, autophagy, and cell cycle arrest in ROS-dependent manner, suggesting a multifaced anticancer agent for OSCC.

Apocynin reduces dihydroethidium fluorescence in naked mole-rat cortex independently of NADPH oxidase

Pharmacological agents that modulate cellular targets offer a powerful approach to interrogate the role of a given component in cellular signalling cascades. However, such drugs are often nonspecific and/or have unexpected off-target effects. One cellular target of interest is the NADPH oxidase (NOX) enzyme family, which consume oxygen and produce reactive oxygen species. Among the most widely used inhibitors of NOX is apocynin, but apocynin also has off-target effects that may interfere with detection assays of hydrogen peroxide (H₂O₂) or directly scavenge H₂O₂ in some cell lines. Nonetheless, apocynin remains widely used for in vivo studies of brain function. Therefore, we used apocynin and another widely-used NOX inhibitor - diphenyleneiodonium (DPI) - to study the role of NOX in ROS homeostasis of hypoxia-tolerant naked mole-rat cortical brain slices during a normoxia➔hypoxia➔reoxygenation protocol. Using fluorescence microscopy, we found that apocynin decreased dihydroethidium fluorescence from naked mole-rat cortex in all treatment conditions by 65-75% of pre-drug normoxic control. This change was rapid, occurring within minutes of drug perfusion, and reversed equally rapidly upon washout. Conversely, apocynin had no effect on 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate, acetyl ester (CM-H₂DCFDA) fluorescence. DPI also had no effect on either fluorescence signal, suggesting that the effect of apocynin is due to indirect actions of the drug and not due to modulation of NOX. Taken together, our results highlight the pitfalls of pharmacological neuroscience and add to the body of evidence suggesting that apocynin is not a useful compound for targeting NOX.

The motor system is exceptionally vulnerable to absence of the ubiquitously expressed superoxide dismutase-1

Superoxide dismutase-1 is a ubiquitously expressed antioxidant enzyme. Mutations in SOD1 can cause amyotrophic lateral sclerosis, probably via a toxic gain-of-function involving protein aggregation and prion-like mechanisms. Recently, homozygosity for loss-of-function mutations in SOD1 has been reported in patients presenting with infantile-onset motor neuron disease. We explored the bodily effects of superoxide dismutase-1 enzymatic deficiency in eight children homozygous for the p.C112Wfs*11 truncating mutation. In addition to physical and imaging examinations, we collected blood, urine and skin fibroblast samples. We used a comprehensive panel of clinically established analyses to assess organ function and analysed oxidative stress markers, antioxidant compounds, and the characteristics of the mutant Superoxide dismutase-1. From around 8 months of age, all patients exhibited progressive signs of both upper and lower motor neuron dysfunction, cerebellar, brain stem, and frontal lobe atrophy and elevated plasma neurofilament concentration indicating ongoing axonal damage. The disease progression seemed to slow down over the following years. The p.C112Wfs*11 gene product is unstable, rapidly degraded and no aggregates were found in fibroblast. Most laboratory tests indicated normal organ integrity and only a few modest deviations were found. The patients displayed anaemia with shortened survival of erythrocytes containing decreased levels of reduced glutathione. A variety of other antioxidants and oxidant damage markers were within normal range. In conclusion, non-neuronal organs in humans show a remarkable tolerance to absence of Superoxide dismutase-1 enzymatic activity. The study highlights the enigmatic specific vulnerability of the motor system to both gain-of-function mutations in SOD1 and loss of the enzyme as in the here depicted infantile superoxide dismutase-1 deficiency syndrome.

Does treatment with autophagy-enhancers and/or ROS-scavengers alleviate behavioral and neurochemical consequences of low-dose rotenone-induced mild mitochondrial dysfunction in mice?

Bipolar-disorder's pathophysiology and the mechanism by which medications exert their beneficial effect is yet unknown, but others' and our data implicate patients' brain mitochondrial-dysfunction and its amendment by mood-stabilizers. We recently designed a novel mouse bipolar-disorder-like model using chronic administration of a low-dose of the oxidative-phosphorylation complex I inhibitor, rotenone. Four and eight weeks rotenone treatment induced manic- and depressive-like behavior, respectively, accompanied by mood-related neurochemical changes. Here we aimed to investigate whether each of the autophagy-enhancers lithium (a mood-stabilizer), trehalose and resveratrol and/or each of the reactive oxygen species (ROS)-scavengers, resveratrol and N-acetylcystein and/or the combinations lithium+resveratrol or trehalose+N-acetylcystein, can ameliorate behavioral and neurochemical consequences of neuronal mild mitochondrial-dysfunction. We observed that lithium, trehalose and N-acetylcystein reversed rotenone-induced manic-like behavior as well as deviations in protein levels of mitochondrial complexes and the autophagy marker LC3-II. This raises the possibility that mild mitochondrial-dysfunction accompanied by impaired autophagy and a very mild increase in ROS levels are related to predisposition to manic-like behavior. On the other hand, although, as expected, most of the drugs tested eliminated the eight weeks rotenone-induced increase in protein levels of all hippocampal mitochondrial complexes, only lithium ubiquitously ameliorated the depressive-like behaviors. We cautiously deduce that aberrant autophagy and/or elevated ROS levels are not involved in predisposition to the depressive phase of bipolar-like behavior. Rather, that amending the depressive-like characteristics requires different mitochondria-related interventions. The latter might be antagonizing N-methyl-D-aspartate receptors (NMDARs), thus protecting from disruption of mitochondrial calcium homeostasis and its detrimental consequences. In conclusion, our findings suggest that by-and-large, among the autophagy-enhancers and ROS-scavengers tested, lithium is the most effective in counteracting rotenone-induced changes. Trehalose and N-acetylcystein may also be effective in attenuating manic-like behavior.

NAC, NAC, Knockin' on Heaven's door: Interpreting the mechanism of action of N-acetylcysteine in tumor and immune cells

N-acetylcysteine (NAC) has been used as a direct scavenger of reactive oxygen species (hydrogen peroxide, in particular) and an antioxidant in cancer biology and immuno-oncology. NAC is the antioxidant drug most frequently employed in studies using tumor cells, immune cells, and preclinical mouse xenografts. Most studies use redox-active fluorescent probes such as dichlorodihydrofluorescein, hydroethidine, mitochondria-targeted hydroethidine, and proprietary kit-based probes (i.e., CellROX Green and CellROX Red) for intracellular detection of superoxide or hydrogen peroxide. Inhibition of fluorescence by NAC was used as a key experimental observation to support the formation of reactive oxygen species and redox mechanisms proposed for ferroptosis, tumor metastasis, and redox signaling in the tumor microenvironment. Reactive oxygen species such as superoxide and hydrogen peroxide stimulate or abrogate tumor cells and immune cells depending on multiple factors. Understanding the mechanism of antioxidants is crucial for interpretation of the results. Because neither NAC nor the fluorescent probes indicated above react directly with hydrogen peroxide, it is critically important to reinterpret the results to advance our understanding of the mechanism of action of NAC and shed additional mechanistic insight on redox-regulated signaling in tumor biology. To this end, this review is focused on how NAC could affect multiple pathways in cancer cells, including iron signaling, ferroptosis, and the glutathione-dependent antioxidant and redox signaling mechanism, and how NAC could inhibit oxidation of the fluorescent probes through multiple mechanisms.

Cytoglobin inhibits non-thermal plasma-induced apoptosis in melanoma cells through regulation of the NRF2-mediated antioxidant response

Melanoma arises from pigment-producing cells called melanocytes located in the basal layers of the epidermis of the skin. Cytoglobin (CYGB) is a ubiquitously expressed hexacoordinated globin that is highly enriched in melanocytes and frequently downregulated during melanomagenesis. Previously, we showed that non-thermal plasma (NTP)-produced reactive oxygen and nitrogen species (RONS) lead to the formation of an intramolecular disulfide bridge that would allow CYGB to function as a redox-sensitive protein. Here, we investigate the cytotoxic effect of indirect NTP treatment in two melanoma cell lines with divergent endogenous CYGB expression levels, and we explore the role of CYGB in determining treatment outcome. Our findings are consistent with previous studies supporting that NTP cytotoxicity is mediated through the production of RONS and leads to apoptotic cell death in melanoma cells. Furthermore, we show that NTP-treated solutions elicit an antioxidant response through the activation of nuclear factor erythroid 2-related factor 2 (NRF2). The knockdown and overexpression of CYGB respectively sensitizes and protects melanoma cells from RONS-induced apoptotic cell death. The presence of CYGB enhances heme-oxygenase 1 (HO-1) and NRF2 protein expression levels, whereas the absence impairs their expression. Moreover, analysis of the CYGB-dependent transcriptome demonstrates the tumor suppressor long non-coding RNA maternally expressed 3 (MEG3) as a hitherto undescribed link between CYGB and NRF2. Thus, the presence of CYGB, at least in melanoma cells, seems to play a central role in determining the therapeutic outcome of RONS-inducing anticancer therapies, like NTP-treated solutions, possessing both tumor-suppressive and oncogenic features. Hence, CYGB expression could be of interest either as a biomarker or as a candidate for future targeted therapies in melanoma.

Metabolic Reprogramming Helps to Define Different Metastatic Tropisms in Colorectal Cancer

Approximately 25% of colorectal cancer (CRC) patients experience systemic metastases, with the most frequent target organs being the liver and lung. Metabolic reprogramming has been recognized as one of the hallmarks of cancer. Here, metabolic and functional differences between two CRC cells with different metastatic organotropisms (metastatic KM12SM CRC cells to the liver and KM12L4a to the lung when injected in the spleen and in the tail vein of mice) were analysed in comparison to their parental non-metastatic isogenic KM12C cells, for a subsequent investigation of identified metabolic targets in CRC patients. Meta-analysis from proteomic and transcriptomic data deposited in databases, qPCR, WB, in vitro cell-based assays, and in vivo experiments were used to survey for metabolic alterations contributing to their different organotropism and for the subsequent analysis of identified metabolic markers in CRC patients. Although no changes in cell proliferation were observed between metastatic cells, KM12SM cells were highly dependent on oxidative phosphorylation at mitochondria, whereas KM12L4a cells were characterized by being more energetically efficient with lower basal respiration levels and a better redox management. Lipid metabolism-related targets were found altered in both cell lines, including LDLR, CD36, FABP4, SCD, AGPAT1, and FASN, which were also associated with the prognosis of CRC patients. Moreover, CD36 association with lung metastatic tropism of CRC cells was validated in vivo. Altogether, our results suggest that LDLR, CD36, FABP4, SCD, FASN, LPL, and APOA1 metabolic targets are associated with CRC metastatic tropism to the liver or lung. These features exemplify specific metabolic adaptations for invasive cancer cells which stem at the primary tumour.

Stimuli-responsive prodrug of non-steroidal anti-inflammatory drug diclofenac: self-immolative drug release with turn-on near-infrared fluorescence

Reactive oxygen species (ROS)-responsive near infrared (NIR) fluorogenic prodrug DCI-ROS is developed for the self-immolative release of diclofenac (DCF) with turn-on fluorescence. The non-toxic prodrug exhibited turn-on red fluorescence with endogenous ROS in cancer cells and inhibited COX-2 expression in the inflammation-induced macrophage cells. The prodrug strategy thus would be helpful for the controlled fluorogenic delivery of DCF for inflammatory diseases.

Severity of neonatal influenza infection is driven by type I interferon and oxidative stress

Neonates exhibit increased susceptibility to respiratory viral infections, attributed to inflammation at the developing pulmonary air-blood interface. IFN I are antiviral cytokines critical to control viral replication, but also promote inflammation. Previously, we established a neonatal murine influenza virus (IV) model, which demonstrates increased mortality. Here, we sought to determine the role of IFN I in this increased mortality. We found that three-day-old IFNAR-deficient mice are highly protected from IV-induced mortality. In addition, exposure to IFNβ 24 h post IV infection accelerated death in WT neonatal animals but did not impact adult mortality. In contrast, IFN IIIs are protective to neonatal mice. IFNβ induced an oxidative stress imbalance specifically in primary neonatal IV-infected pulmonary type II epithelial cells (TIIEC), not in adult TIIECs. Moreover, neonates did not have an infection-induced increase in antioxidants, including a key antioxidant, superoxide dismutase 3, as compared to adults. Importantly, antioxidant treatment rescued IV-infected neonatal mice, but had no impact on adult morbidity. We propose that IFN I exacerbate an oxidative stress imbalance in the neonate because of IFN I-induced pulmonary TIIEC ROS production coupled with developmentally regulated, defective antioxidant production in response to IV infection. This age-specific imbalance contributes to mortality after respiratory infections in this vulnerable population.

Free spermidine evokes superoxide radicals that manifest toxicity

Spermidine and other polyamines alleviate oxidative stress, yet excess spermidine seems toxic to Escherichia coli unless it is neutralized by SpeG, an enzyme for the spermidine N-acetyl transferase function. Thus, wild-type E. coli can tolerate applied exogenous spermidine stress, but ΔspeG strain of E. coli fails to do that. Here, using different reactive oxygen species (ROS) probes and performing electron paramagnetic resonance spectroscopy, we provide evidence that although spermidine mitigates oxidative stress by lowering overall ROS levels, excess of it simultaneously triggers the production of superoxide radicals, thereby causing toxicity in the ΔspeG strain. Furthermore, performing microarray experiment and other biochemical assays, we show that the spermidine-induced superoxide anions affected redox balance and iron homeostasis. Finally, we demonstrate that while RNA-bound spermidine inhibits iron oxidation, free spermidine interacts and oxidizes the iron to evoke superoxide radicals directly. Therefore, we propose that the spermidine-induced superoxide generation is one of the major causes of spermidine toxicity in E. coli.

Ginsenoside Rk1 regulates glutamine metabolism in hepatocellular carcinoma through inhibition of the ERK/c-Myc pathway

Hepatocellular carcinoma (HCC) is one of the most prevalent and deadly cancers in the world. Recently, suppression of glutamine metabolism has become one of the hottest therapy targets for cancer treatment. There is a growing amount of research that indicates that ginsenosides possess good anti-tumor activity. However, the effect of ginsenoside Rk1 on glutamine metabolism in HCC is unclear. In this study, Rk1 was demonstrated to be effective at inhibiting the proliferation of HCC through the induction of cell cycle arrest and apoptosis. Especially, Rk1 was shown for the first time to inhibit glutamine metabolism in HCC. Rk1 downregulates GLS1 expression, and consequently decreases the GSH production, stimulating ROS accumulation to induce apoptosis. In addition, transcriptomic results showed that the ERK/c-Myc signaling pathway was enriched in HepG2. Rk1 exerts an inhibitory effect on glutamine metabolism in HCC by regulating the ERK/c-Myc signaling pathway, and inducing apoptosis in vitro and in vivo with less toxicity. Therefore, ginsenoside Rk1 could be a promising candidate for the clinical treatment of HCC.

Baicalein inhibits cell proliferation and enhances apoptosis in human A549 cells and benzo(a)pyrene-induced pulmonary carcinogenesis in mice

Our current study is done to explore the possible mechanisms to elaborate on the growth inhibitory effect of baicalein (BE) in human lung carcinoma. Initially, BE (25 and 50 µM) treatment for 24 h, suppressed the viability and inhibited population growth in A549 cells. BE upholds the production of reactive oxygen species (ROS) with concomitant replenishment of glutathione, catalase, and glutathione peroxidase activity. The expression level of nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 markedly increased after BE treatment will intimidate A549 cells proliferation by the ROS-independent pathway via the antioxidant pathway. In vivo investigations were carried out on BE (12 mg/kg, oral) in benzo(a)pyrene (B(a)P; 50 mg/kg, oral) induced lung carcinogenesis in mice. BE induces caspase-dependent apoptosis by increasing the levels of cytosolic cytochrome c accompanied by upregulating the outflow of p53, Bax, and caspase-3 with a concomitant abatement in the outflow of Bcl-2 in both in vitro and in vivo. In the murine model, BE treatment hindered the countenance of proliferation-related proteins (argyrophilic nucleolar organizing regions and proliferating cell nuclear antigen). Additionally, appraisal of the cell nucleus by transmission electron microscopic assessment uncovered that BE treatment adequately counteracts B(a)P-induced lung cancer cell survival. During the transition of the G₀ /G₁ phase, BE is arrested in the cell cycle process. This might be the cause of a substantial increase in the appearance of p21^Cip1 with concomitant downregulating the expressions of CDK4, cyclin D, and cyclin E both in vitro and in vivo. Our results conclude that BE treatment induced apoptosis and repressed proliferation both in vitro and in vivo of human lung carcinoma.

Juxtamembrane 2 mimic peptide competitively inhibits mitochondrial trafficking and activates ROS-mediated apoptosis pathway to exert anti-tumor effects

Our previous study demonstrates that a juxtamembrane 2 (JM2) mimic peptide can inhibit proliferation and induce apoptosis of tumor cells. However, the mechanism remains unclear. In this study, JM2 is found to suppress the growth of 4T1 breast tumors by inducing apoptosis and inhibiting the proliferation of 4T1 tumor cells. Further study indicates that JM2 can stimulate the mitochondria to gather near the microtubule-organizing center of tumor cells and subsequently induce ROS-induced ROS release responses, which results in mitochondrial dysfunction and mitochondria-mediated apoptosis. In addition, JM2 can arrest cell cycle in S phase by regulating the expression of cell cycle-related proteins and consequently inhibit proliferation of tumor cells. Then, a previously designed JM2 grafted hyaluronic acid (HA) injectable hydrogel system (HA-JM2) is injected in a breast tumor-resected model and the HA-JM2 hydrogel can inhibit the malignant proliferation of residual tumor cells and suppress the breast tumor recurrence. These findings not only confirm the application potentials of JM2 in anti-tumor therapy and tumor post-surgery treatments but also provide greater understanding on the mechanisms by which JM2 inhibits tumor growth.

Necrosulfonamide Selectively Induces DNA Double-Strand Breaks in Acute Myeloid Leukemia Cells

Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy that causes endless pain for patients and accounts for thousands of deaths worldwide. The development of an effective AML treatment is a topic of ongoing interest. Here, we demonstrated that a pyroptosis inhibitor necrosulfonamide (NSA) can selectively induce highly toxic double-strand breaks and kill AML cells. Mechanistically, reactive oxygen species (ROS) were the key effectors mediating the toxicity of NSA. These results probably indicate that NSA is a novel candidate for the treatment of AML.

Heterogeneity of human corneal endothelium implicates lncRNA NEAT1 in Fuchs endothelial corneal dystrophy

The corneal endothelium is critical for maintaining corneal clarity by mediating hydration through barrier and pump functions. Progressive loss of corneal endothelial cells during aging has been associated with the development of Fuchs endothelial corneal dystrophy (FECD), one of the main causes of cornea-related vision loss. The mechanisms underlying FECD development remain elusive. Single-cell RNA sequencing of isolated healthy human corneas discovered 4 subpopulations of corneal endothelial cells with distinctive signatures. Unsupervised clustering analysis uncovered nuclear enriched abundant transcript 1 (NEAT1), a long non-coding RNA (lncRNA), as the top expressed gene in the C0-endothelial subpopulation, but markedly downregulated in FECD. Consistent with human corneas, a UVA-induced mouse FECD model validated the loss of NEAT1 expression. Loss of NEAT1 function by an in vivo genetic approach reproduced the exacerbated phenotype of FECD by ablating corneal endothelial cells. Conversely, gain of function by a CRISPR-activated adenoviral delivery system protected corneas from UVA-induced FECD. Our findings provide novel mechanistic insights into the development of FECD, and targeting NEAT1 offers an attractive approach for treating FECD.

Carbon monoxide releasing molecule-2 attenuates angiotensin II-induced IL-6/Jak2/Stat3-associated inflammation by inhibiting NADPH oxidase- and mitochondria-derived ROS in human aortic smooth muscle cells

Abdominal aortic aneurysm (AAA) is a common inflammatory vascular disease. Angiotensin II (Ang II) involves in AAA progression by promoting the proliferation and migration of vascular smooth muscle cells, the degradation of extracellular matrices, and the generation of ROS to lead to vascular inflammation. Carbon monoxide releasing molecule-2 (CORM-2) is known to exert anti-inflammatory and antioxidant activities. However, it remains unclear whether CORM-2 can suppress Ang II-induced vascular inflammation to prevent AAA progression. Therefore, this study aimed to investigate the vasoprotective effects of CORM-2 against Ang II-induced inflammatory responses of human aortic smooth muscle cells (HASMCs) and the underlying mechanisms of those effects. The results showed that Ang II induced inflammatory responses of HASMCs via NADPH oxidase- and mitochondria-derived ROS/NF-κB/IL-6/Jak2/Stat3 pathway which was attenuated by the pretreatment with CORM-2. Additionally, CORM-2 further exhibited anti-inflammatory activities in Ang II-stimulated HASMCs, as indicated by the reduction of monocyte adhesion to HASMCs and migration of HASMCs via the suppression of ICAM-1 and VCAM-1 as well as MMP-2 and MMP-9 levels, respectively. Moreover, Ang II-induced COX-2-mediated PGE₂ secretion was also inhibited by the pretreatment with CORM-2. Importantly, our data demonstrated that CORM-2 reversed Ang II-induced IL-6 overexpression dependent on Nrf2 activation and HO-1 expression. Taken together, the present study indicates that CORM-2-induced Nrf2/HO-1 alleviates IL-6/Jak2/Stat3-mediated inflammatory responses to Ang II by inhibiting NADPH oxidase- and mitochondria-derived ROS, suggesting that CORM-2 is a promising pharmacologic candidate to reverse the pathological changes involved in the inflammation of vessel wall for the prevention and treatment of AAA.

Early rRNA processing is a stress-dependent regulatory event whose inhibition maintains nucleolar integrity

The production of ribosomes is an energy-intensive process owing to the intricacy of these massive macromolecular machines. Each human ribosome contains 80 ribosomal proteins and four non-coding RNAs. Accurate assembly requires precise regulation of protein and RNA subunits. In response to stress, the integrated stress response (ISR) rapidly inhibits global translation. How rRNA is coordinately regulated with the rapid inhibition of ribosomal protein synthesis is not known. Here, we show that stress specifically inhibits the first step of rRNA processing. Unprocessed rRNA is stored within the nucleolus, and when stress resolves, it re-enters the ribosome biogenesis pathway. Retention of unprocessed rRNA within the nucleolus aids in the maintenance of this organelle. This response is independent of the ISR or inhibition of cellular translation but is independently regulated. Failure to coordinately control ribosomal protein translation and rRNA production results in nucleolar fragmentation. Our study unveils how the rapid translational shut-off in response to stress coordinates with rRNA synthesis production to maintain nucleolar integrity.

N-Acetylcysteine Inhibits Aortic Stenosis Progression in a Murine Model by Blocking Shear-Induced Activation of Platelet Latent Transforming Growth Factor Beta 1

Objective: Aortic stenosis (AS) is characterized by narrowing of the aortic valve opening, resulting in peak blood flow velocity that induces high wall shear stress (WSS) across the valve. Severe AS leads to heart failure and death. There is no treatment available for AS other than valve replacement. Platelet-derived transforming growth factor beta 1 (TGF-β1) partially contributes to AS progression in mice, and WSS is a potent activator of latent TGF-β1. N-acetylcysteine (NAC) inhibits WSS-induced TGF-β1 activation in vitro. We hypothesize that NAC will inhibit AS progression by inhibiting WSS-induced TGF-β1 activation. Approach: We treated a cohort of Ldlr(-/-)Apob(100/100) low density lipoprotein receptor (LDLR) mice fed a high-fat diet with NAC (2% in drinking water) at different stages of disease progression and measured its effect on AS progression and TGF-β1 activation. Results: Short-term NAC treatment inhibited AS progression in mice with moderate and severe AS relative to controls, but not in LDLR mice lacking platelet-derived TGF-β1 (TGF-β1platlet-KO-LDLR). NAC treatment reduced TGF-β signaling, p-Smad2 and collagen levels, and mesenchymal transition from isolectin B4 and CD45-positive cells in LDLR mice. Mechanistically, NAC treatment resulted in plasma NAC concentrations ranging from 75.5 to 449.2 ng/mL, which were sufficient to block free thiol labeling of plasma proteins and reduce active TGF-β1 levels without substantially affecting reactive oxygen species-modified products in valvular cells. Conclusions: Short-term treatment with NAC inhibits AS progression by inhibiting WSS-induced TGF-β1 activation in the LDLR mouse model of AS, motivating a clinical trial of NAC and/or other thiol-reactive agent(s) as a potential therapy for AS.

The effects of real and simulated microgravity on cellular mitochondrial function

Astronauts returning from space shuttle missions or the International Space Station have been diagnosed with various health problems such as bone demineralization, muscle atrophy, cardiovascular deconditioning, and vestibular and sensory imbalance including visual acuity, altered metabolic and nutritional status, and immune system dysregulation. These health issues are associated with oxidative stress caused by a microgravity environment. Mitochondria are a source of reactive oxygen species (ROS). However, the molecular mechanisms through which mitochondria produce ROS in a microgravity environment remain unclear. Therefore, this review aimed to explore the mechanism through which microgravity induces oxidative damage in mitochondria by evaluating the expression of genes and proteins, as well as relevant metabolic pathways. In general, microgravity-induced ROS reduce mitochondrial volume by mainly affecting the efficiency of the respiratory chain and metabolic pathways. The impaired respiratory chain is thought to generate ROS through premature electron leakage in the electron transport chain. The imbalance between ROS production and antioxidant defense in mitochondria is the main cause of mitochondrial stress and damage, which leads to mitochondrial dysfunction. Moreover, we discuss the effects of antioxidants against oxidative stress caused by the microgravity environment space microgravity in together with simulated microgravity (i.e., spaceflight or ground-based spaceflight analogs: parabolic flight, centrifugal force, drop towers, etc.). Further studies should be taken to explore the effects of microgravity on mitochondrial stress-related diseases, especially for the development of new therapeutic drugs that can help increase the health of astronauts on long space missions.

Induction of Premature Cell Senescence Stimulated by High Doses of Antioxidants Is Mediated by Endoplasmic Reticulum Stress

In our previous study, we found that high doses of several substances with antioxidant capacities (Tempol, resveratrol, diphenyleneiodonium) can cause genotoxic stress and induce premature senescence in the human mesenchymal stem cells (MSCs). Here, using whole-transcriptome analysis, we revealed the signs of endoplasmic reticulum stress and unfolded protein response (UPR) in MSCs stressed with Tempol and resveratrol. In addition, we found the upregulation of genes, coding the UPR downstream target APC/C, and E3 ubiquitin ligase that regulate the stability of cell cycle proteins. We performed the molecular analysis, which further confirmed the untimely degradation of APC/C targets (cyclin A, geminin, and Emi1) in MSCs treated with antioxidants. Human fibroblasts responded to antioxidant applications similarly. We conclude that endoplasmic reticulum stress and impaired DNA synthesis regulation can be considered as potential triggers of cell damage and premature senescence stimulated by high-dose antioxidant treatments.