Metformin Induces Lipogenesis and Apoptosis in H4IIE Hepatocellular Carcinoma Cells

Metformin is the most widely used anti-diabetic drug that helps maintain normal blood glucose levels primarily by suppressing hepatic gluconeogenesis in type II diabetic patients. We previously found that metformin induces apoptotic death in H4IIE rat hepatocellular carcinoma cells. Despite its anti-diabetic roles, the effect of metformin on hepatic de novo lipogenesis (DNL) remains unclear. We investigated the effect of metformin on hepatic DNL and apoptotic cell death in H4IIE cells. Metformin treatment stimulated glucose consumption, lactate production, intracellular fat accumulation, and the expressions of lipogenic proteins. It also stimulated apoptosis but reduced autophagic responses. These metformin-induced changes were clearly reversed by compound C, an inhibitor of AMP-activated protein kinase (AMPK). Interestingly, metformin massively increased the production of reactive oxygen species (ROS), which was completely blocked by compound C. Metformin also stimulated the phosphorylation of p38 mitogen-activated protein kinase (p38MAPK). Finally, inhibition of p38MAPK mimicked the effects of compound C, and suppressed the metformin-induced fat accumulation and apoptosis. Taken together, metformin stimulates dysregulated glucose metabolism, intracellular fat accumulation, and apoptosis. Our findings suggest that metformin induces excessive glucose-induced DNL, oxidative stress by ROS generation, activation of AMPK and p38MAPK, suppression of autophagy, and ultimately apoptosis.

Redox Oscillations Activate Thermodynamically Stable Iron Minerals for Enhanced Reactive Oxygen Species Production

Reactive oxygen species (ROS) play key roles in driving biogeochemical processes. Recent studies have revealed nonphotochemical electron transfer from redox-active substances (e.g., iron minerals) to oxygen as a new route for ROS production. Yet, naturally occurring iron minerals mainly exist in thermodynamically stable forms, restraining their potential for driving ROS production. Here, we report that tide-induced redox oscillations can activate thermodynamically stable iron minerals for enhanced ROS production. ^•OH production in intertidal soils (15.8 ± 0.5 μmol/m²) was found to be 5.9-fold more efficient than those in supratidal soils. Moreover, incubation of supratidal soils under tidal redox fluctuations dramatically enhanced ^•OH production by 4.3-fold. The tidal hydrology triggered redox alternation between biotic reduction and abiotic oxidation and could accelerate the production of reactive ferrous ions and amorphous ferric oxyhydroxides, making thermodynamically stable iron minerals into redox-active metastable iron phases (RAMPs) with reduced crystallinity and promoting surface electrochemical activities. Those RAMPs displayed enhanced redox activity for ROS production. Investigations of nationwide coastal soils verified that tide-induced redox oscillations could ubiquitously activate soils for enhanced ROS production. Our study demonstrates the effective formation of RAMPs from redox oscillations by hydrological perturbations, which provides new insights into natural ROS sources.

Mitochondrial impairment and downregulation of Drp1 phosphorylation underlie the antiproliferative and proapoptotic effects of alantolactone on oral squamous cell carcinoma cells

BACKGROUND

Oral squamous cell carcinoma (OSCC) is one of the most prevalent and fatal oral cancers. Mitochondria-targeting therapies represent promising strategies against various cancers, but their applications in treating OSCC are limited. Alantolactone (ALT) possesses anticancer properties and also regulates mitochondrial events. In this study, we explored the effects of ALT on OSCC and the related mechanisms.

METHODS

The OSCC cells were treated with varying concentrations and duration of ALT and N-Acetyl-L-cysteine (NAC). The cell viability and colony formation were assessed. The apoptotic rate was evaluated by flow cytometry with Annexin V-FITC/PI double staining. We used DCFH-DA and flow cytometry to detect reactive oxygen species (ROS) production and DAF-FM DA to investigate reactive nitrogen species (RNS) level. Mitochondrial function was reflected by mitochondrial reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and ATP levels. KEGG enrichment analyses determined the mitochondrial-related hub genes involved in OSCC progression. Dynamin-related protein 1 (Drp1) overexpression plasmids were further transfected into the cells to analyze the role of Drp1 in OSCC progression. Immunohistochemistry staining and western blot verified the expression of the protein.

RESULTS

ALT exerted anti-proliferative and pro-apoptosis effects on OSCC cells. Mechanistically, ALT elicited cell injury by promoting ROS production, mitochondrial membrane depolarization, and ATP depletion, which were reversed by NAC. Bioinformatics analysis showed that Drp1 played a crucial role in OSCC progression. OSCC patients with low Drp1 expression had a higher survival rate. The OSCC cancer tissues presented higher phosphorylated-Drp1 and Drp1 levels than the normal tissues. The results further showed that ALT suppressed Drp1 phosphorylation in OSCC cells. Moreover, Drp1 overexpression abolished the reduced Drp1 phosphorylation by ALT and promoted the cell viability of ALT-treated cells. Drp1 overexpression also reversed the mitochondrial dysfunction induced by ALT, with decreased ROS production, and increased mitochondrial membrane potential and ATP level.

CONCLUSIONS

ALT inhibited proliferation and promoted apoptosis of oral squamous cell carcinoma cells via impairment of mitochondrial homeostasis and regulation of Drp1. The results provide a solid basis for ALT as a therapeutic candidate for treating OSCC, with Drp1 being a novel therapeutic target in treating OSCC.

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.

Over-activation of TRPM2 ion channel accelerates blood-spinal cord barrier destruction in diabetes combined with spinal cord injury rat

Spinal cord injury (SCI) is a devastating neurological disorder that often results in loss of motor and sensory function. Diabetes facilitates the blood-spinal cord barrier (BSCB) destruction and aggravates SCI recovery. However, the molecular mechanism underlying it is still unclear. Our study has focused on transient receptor potential melastatin 2 (TRPM2) channel and investigated its regulatory role on integrity and function of BSCB in diabetes combined with SCI rat. We have confirmed that diabetes is obviously not conductive to SCI recovery through accelerates BSCB destruction. Endothelial cells (ECs) are the important component of BSCB. It was observed that diabetes significantly worsens mitochondrial dysfunction and triggers excessive apoptosis of ECs in spinal cord from SCI rat. Moreover, diabetes impeded neovascularization in spinal cord from SCI rat with decreases of VEGF and ANG1. TRPM2 acts as a cellular sensor of ROS. Our mechanistic studies showed that diabetes significantly induces elevated ROS level to activate TRPM2 ion channel of ECs. Then, TRPM2 channel mediated the Ca²⁺ influx and subsequently activated p-CaMKII/eNOS pathway, and which in turn triggered the ROS production. Consequently, over-activation of TRPM2 ion channel results in excessive apoptosis and weaker angiogenesis during SCI recovery. Inhibition of TRPM2 with 2-Aminoethyl diphenylborinate (2-APB) or TRPM2 siRNA will ameliorate the apoptosis of ECs and promote angiogenesis, subsequently enhance BSCB integrity and improve the locomotor function recovery of diabetes combined with SCI rat. In conclusion, TRPM2 channel may be a key target for the treatment of diabetes combined with SCI rat.

ROS-generating alginate-coated gold nanorods as biocompatible nanosonosensitisers for effective sonodynamic therapy of cancer

Sonodynamic therapy (SDT) emerges as a promising non-invasive alternative for eradicating malignant tumours. However, its therapeutic efficacy remains limited due to the lack of sonosensitisers with high potency and biosafety. Previously, gold nanorods (AuNRs) have been extensively studied for their applications in photodynamic or photothermal cancer therapy, but their sonosensitising properties are largely unexplored. Here, we reported the applicability of alginate-coated AuNRs (AuNRs^ALG) with improved biocompatibility profiles as promising nanosonosensitisers for SDT for the first time. AuNRs^ALG were found stable under ultrasound irradiation (1.0 W/cm², 5 min) and maintained structural integrity for 3 cycles of irradiation. The exposure of the AuNRs^ALG to ultrasound irradiation (1.0 W/cm², 5 min) was shown to enhance the cavitation effect significantly and generate a 3 to 8-fold higher amount of singlet oxygen (¹O₂) than other reported commercial titanium dioxide nanosonosensitisers. AuNRs^ALG exerted dose-dependent sonotoxicity on human MDA-MB-231 breast cancer cells in vitro, with ∼ 81% cancer cell killing efficacy at a sub-nanomolar level (IC₅₀ was 0.68 nM) predominantly through apoptosis. The protein expression analysis showed significant DNA damage and downregulation of anti-apoptotic Bcl-2, suggesting AuNRs^ALG induced cell death through the mitochondrial pathway. The addition of mannitol, a reactive oxygen species (ROS) scavenger, inhibited cancer-killing effect of AuNRs^ALG-mediated SDT, further verifying that the sonotoxicity of AuNRs^ALG is driven by the production of ROS. Overall, these results highlight the potential application of AuNRs^ALG as an effective nanosonosensitising agent in clinical settings.

Vitamin K3 (Menadione) is a multifunctional microbicide acting as a photosensitizer and synergizing with blue light to kill drug-resistant bacteria in biofilms

Cutaneous bacterial wound infections typically involve gram-positive cocci such as Staphylococcus aureus (SA) and usually become biofilm infections. Bacteria in biofilms may be 100-1000-fold more resistant to an antibiotic than the clinical laboratory minimal inhibitory concentration (MIC) for that antibiotic, contributing to antimicrobial resistance (AMR). AMR is a growing global threat to humanity. One pathogen-antibiotic resistant combination, methicillin-resistant SA (MRSA) caused more deaths globally than any other such combination in a recent worldwide statistical review. Many wound infections are accessible to light. Antimicrobial phototherapy, and particularly antimicrobial blue light therapy (aBL) is an innovative non-antibiotic approach often overlooked as a possible alternative or adjunctive therapy to reduce antibiotic use. We therefore focused on aBL treatment of biofilm infections, especially MRSA, focusing on in vitro and ex vivo porcine skin models of bacterial biofilm infections. Since aBL is microbicidal through the generation of reactive oxygen species (ROS), we hypothesized that menadione (Vitamin K3), a multifunctional ROS generator, might enhance aBL. Our studies suggest that menadione can synergize with aBL to increase both ROS and microbicidal effects, acting as a photosensitizer as well as an ROS recycler in the treatment of biofilm infections. Vitamin K3/menadione has been given orally and intravenously worldwide to thousands of patients. We conclude that menadione/Vitamin K3 can be used as an adjunct to antimicrobial blue light therapy, increasing the effectiveness of this modality in the treatment of biofilm infections, thereby presenting a potential alternative to antibiotic therapy, to which biofilm infections are so resistant.

Melatonin and erastin emerge synergistic anti-tumor effects on oral squamous cell carcinoma by inducing apoptosis, ferroptosis, and inhibiting autophagy through promoting ROS

BACKGROUND

Oral squamous cell carcinomas are one of the most common cancers worldwide with aggressive behavior and poor prognosis. Reactive oxygen species (ROS) are associated with cancer and cause various types of regulated cell death (RCD). Inducing the RCD pathway by modulating ROS levels is imperative to conquer cancers. The aim of this study is to investigate the synergistic anticancer effects of melatonin and erastin on ROS modulation and subsequent RCD induction.

METHODS

Human tongue squamous cell carcinoma cell lines (SCC-15 cells) were treated with melatonin, erastin, or their combination. Cell viability, ROS levels, autophagy, apoptosis, and ferroptosis levels were tested according to the results of the PCR array, which were verified with/without the induction and inhibition of ROS by H₂O₂ and N-acetyl-L-cysteine, respectively. In addition, a mouse-based subcutaneous oral cancer xenograft model was constructed to identify the effects of melatonin, erastin, and their combination on the autophagy, apoptosis, and ferroptosis levels in isolated tumor tissues.

RESULTS

ROS levels were increased by the administration of melatonin at high concentrations (mM), and the combination of melatonin with erastin enhanced the levels of malonic dialdehyde, ROS, and lipid ROS, and reduced the levels of glutamate and glutathione. SQSTM1/p62, LC3A/B, cleaved caspase-3, and PARP1 protein levels in SCC-15 cells were also increased by melatonin plus erastin treatment, which further increased as ROS accumulated, and decreased as ROS levels were suppressed. Combined treatment of melatonin and erastin markedly reduced the tumor size in vivo, demonstrated no obvious systemic side effects, and significantly enhanced the apoptosis and ferroptosis levels in the tumor tissues, in parallel with decreased autophagy levels.

CONCLUSIONS

Melatonin combined with erastin exhibits synergistic anticancer effects without adverse reactions. Herein, this combination might become a promising alternative strategy for oral cancer treatment.

Gamma irradiation induces a pro-apoptotic state in longer stored platelets, without progressing to an overt apoptosis by day 7 of storage

BACKGROUND

Although gamma-irradiation to platelet products is a standard method to prevent the risk of TA-GVHD in vulnerable recipients, it induces some proteomic and redox changes, of which irradiation-induced ROS increments may potentiate platelet mitochondrial dysfunction. However, whether these changes cause platelet apoptosis, or affect their viability during storage, is the main subject of this study.

METHODS

PLT-rich plasma PC was split into two bags, one kept as control while other was subjected to gamma-irradiation. Within 7-days storage, cytosolic and mitochondrial levels of cytochrome c and pro-apoptotic molecules of Bak and Bax were evaluated by western-blotting. Intraplatelet active caspase (using FAM-DEVD-FMK) and PS-exposure were detected by flowcytometry. Caspase activity in platelet lysate was also confirmed by immunofluorescence detection of Caspase-3/7 Substrate N-Ac-DEVD-N'-MC-R110 while platelet viability was evaluated with MTT assays.

RESULTS

Cytosolic cytochrome c gradually increased while its mitochondrial content steadily declined during 7 days of storage. In a contrary trend, reverse patterns were observed for Bak and Bax expressions. Gamma-irradiated platelets showed higher release of mitochondrial cytochrome c that reflected by higher cytosolic cytochrome c levels on day 7 of storage. Concurrently mitochondrial pro-apoptotic Bak and Bax proteins increased on day 7 in irradiated products. However, gamma-irradiation didn't significantly increase caspase activity or PS-exposure, nor did it decrease platelet viability.

CONCLUSION

Here, consistent with studies on "gamma-irradiation-induced oxidative stress", we showed that gamma-ray also increases platelet pro-apoptotic signals during storage, although not strongly enough to affect platelet viability by overt apoptosis induction. Conclusively, whether supplementing ROS scavengers or antioxidants to irradiated platelets can improve their quality during storage may be of interest for future research.

Calotropis gigantea stem bark extract activates HepG2 cell apoptosis through ROS and its effect on cytochrome P450

The 95% ethanolic extract of the dry powder of Calotropis gigantea (C. gigantea) stem bark was separated by fractionation with different solutions to yield 4 fractions: dichloromethane (CGDCM), ethyl acetate (CGEtOAc), and water (CGW). This research focused on CGDCM-induced apoptosis in HepG2 cells with IC50 and above-IC50 values, which provide useful information for future anticancer applications. CGDCM had lower cytotoxicity on normal lung fibroblast IMR-90 cells than on HepG2 cells. Apoptotic induction of CGDCM was mediated by decreased fatty acid and ATP synthesis while increasing reactive oxygen species production. The effects of the four extracts on the activity of the four major CYP450 isoforms (CYP1A2, CYP2C9, CYP2E1 and CYP3A4) were determined using the CYP-specific model activity of each isoform. All four fractions of the extract were shown to be poor inhibitors of CYP1A2 and CYP2E1 (IC50 > 1000 μg/mL) and moderate inhibitors of CYP3A4 (IC50 = 56.54-296.9 μg/mL). CGDCM and CGW exerted moderate inhibition activities on CYP2C9 (IC50 = 59.56 and 46.38 μg/mL, respectively), but CGEtOH and CGEtOAc exhibited strong inhibition activities (IC50 = 12.11 and 20.43 μg/mL, respectively). It is proposed that C. gigantea extracts at high doses have potential for further studies to develop alternative anticancer applications. Inhibiting CYP2C9 activity may also lead to drug-herb interactions.

Loureirin C inhibits ferroptosis after cerebral ischemia reperfusion through regulation of the Nrf2 pathway in mice

BACKGROUND

Ischemic stroke (IS) is considered as a serious cerebral vascular disease. Ferroptosis is a novel type of regulated cell death (RCD), that closely related to the occurrence and progress of IS. Loureirin C, a type of dihydrochalcone compound derived from the Chinese Dragon's blood (CDB). The effective components extracted from CDB have shown neuroprotective effects in ischemia reperfusion models. However, the role of Loureirin C in mice after IS is not well understood. Thus, it is worth to identify the effect and mechanism of Loureirin C on IS.

PURPOSE

The present research aims to prove the existence of ferroptosis in IS and explore whether Loureirin C can inhibit ferroptosis by regulating nuclear factor E2 related factor 2 (Nrf2) pathway in mice and exert neuroprotective effects on IS models.

METHODS

Middle cerebral artery occlusion and reperfusion (MCAO/R) model was established to evaluate the occurrence of ferroptosis and the potential Loureirin C brain-protective effect in vivo. The analysis of free iron, glutamate content, reactive oxygen species (ROS) and lipid peroxidation levels, along with transmission electron microscope (TEM) was applied to prove the existence of ferroptosis. The function of Loureirin C on Nrf2 nuclear translocation was verified by immunofluorescence staining. In vitro, primary neurons and SH-SY5Y cells were processed with Loureirin C after oxygen and glucose deprivation-reperfusion (OGD/R). ELISA kits, western blotting, co-immunoprecipitation (Co-IP) analysis, immunofluorescence, and quantitative real-time PCR were devoted to proving the neuroprotective effects of Loureirin C on IS via regulating ferroptosis and Nrf2 pathways.

RESULTS

The results showed that Loureirin C not only dramatically alleviated brain injury and inhibited neurons ferroptosis in mice after MCAO/R, but also dose-dependently reduce ROS accumulation in ferroptosis after OGD/R. Further, Loureirin C inhibits ferroptosis by activating Nrf2 pathway, and promoting nuclear translocation of Nrf2. Besides, Loureirin C increases heme oxygenase 1 (HO-1), quinone oxidoreductase 1 (NQO1) and glutathione peroxidase 4 (GPX4) content after IS. Intriguingly, the anti-ferroptosis effect of Loureirin C is weakened by Nrf2 knockdown.

CONCLUSION

Our discoveries first revealed that the inhibitory action of Loureirin C on ferroptosis may greatly depend on its adjusting effect on the Nrf2 pathway, suggesting that Loureirin C could act as a novel anti-ferroptosis candidate and play a therapeutic role in IS. These novel discoveries on the role of Loureirin C on IS models reveal an innovative method that may contribute to neuroprotection for the prevention of IS.

The calcium channel modulator 2-APB hydrolyzes in physiological buffers and acts as an effective radical scavenger and inhibitor of the NADPH oxidase 2

2-aminoethoxydiphenyl borate (2-APB) is commonly used as a tool to modulate calcium signaling in physiological studies. 2-APB has a complex pharmacology and acts as activator or inhibitor of a variety of Ca²⁺ channels and transporters. While unspecific, 2-APB is one of the most-used agents to modulate store-operated calcium entry (SOCE) mediated by the STIM-gated Orai channels. Due to its boron core structure, 2-APB tends to readily hydrolyze in aqueous environment, a property that results in a complex physicochemical behavior. Here, we quantified the degree of hydrolysis in physiological conditions and identified the hydrolysis products diphenylborinic acid and 2-aminoethanol by NMR. Notably, we detected a high sensitivity of 2-APB/diphenylborinic acid towards decomposition by hydrogen peroxide to compounds such as phenylboronic acid, phenol, and boric acid, which were, in contrast to 2-APB itself and diphenylborinic acid, insufficient to affect SOCE in physiological experiments. Consequently, the efficacy of 2-APB as a Ca²⁺ signal modulator strongly depends on the reactive oxygen species (ROS) production within the experimental system. The antioxidant behavior of 2-APB towards ROS and its resulting decomposition are inversely correlated to its potency to modulate Ca²⁺ signaling as shown by electron spin resonance spectroscopy (ESR) and Ca²⁺ imaging. Finally, we observed a strong inhibitory effect of 2-APB, i.e., its hydrolysis product diphenylborinic acid, on NADPH oxidase (NOX2) activity in human monocytes. These new 2-APB properties are highly relevant for Ca²⁺ and redox signaling studies and for pharmacological application of 2-APB and related boron compounds.

The effect of infusion time on Echium amoenum extract -induced hepatotoxicity in vitro

Echium amoenum is an annual herb native to the northern mountains of Iran which has medicinal application. Petals of Echium amoenum (Gole-Gavzaban) is one of the most valuable medicinal plants in Iranian folk medicine. The dry petals of E. amoenum have long been used as a sedative, tonic, anxiolytic and as a treatment for sore throat, cough and inflammation. Previous studies have shown that petals of E. amoenum contain four toxic pyrrolizidine alkaloids but conflicting results have been acquired in experimental studies investigating the hepatotoxicy of E. amoenum. However, the direct effect of E. amoenum on liver cells and the complete mechanisms of its possible cytotoxic effects toward these cells remain to be defined. The main aim of this study was to assay the mechanisms underlying the toxic effects of E. amoenum toward hepG2 cells. E. amoenum extract was obtained by infusion of dried petals in hot water (90 centigrade) for 15 or 30 min. Cell viability and mechanistic parameters were determined following 12 h incubation of hepG2 with E. amoenum extract that was obtained after 15 or 30 min infusion. The results indicated that E. amoenum extract exerts cytotoxic effects on hepG2 cells, probably through mitochondrial and lysosomal damage induced by glutathione depletion and oxidative stress.

Carteolol triggers senescence via activation of β-arrestin-ERK-NOX4-ROS pathway in human corneal endothelial cells in vitro

Carteolol is a commonly-used topical medication for primary open-angle glaucoma. However, long-term and frequent ocular application of carteolol entails its residuals at low concentration in the aqueous humor for a long duration and may exert latent toxicity in the human corneal endothelial cells (HCEnCs). Here, we treated the HCEnCs in vitro with 0.0117% carteolol for 10 days. Thereafter, we removed the cartelolol and normally cultured the cells for 25 days to investigate the chronical toxicity of carteolol and the underlying mechanism. The results exhibited that 0.0117% carteolol induces senescent features in the HCEnCs, such as increased senescence-associated β-galactosidase positive rates, enlarged relative cell area and upregulated p16^INK4A and senescence-associated secretory phenotypes, including IL-1α, TGF-β1, IL-10, TNF-α, CCL-27, IL-6 and IL-8, as well as decreased Lamin B1 expression and cell viability and proliferation. Thereby, further exploration demonstrated that the carteolol activates β-arrestin-ERK-NOX4 pathway to increase reactive oxygen species (ROS) production that imposes oxidative stress on energetic metabolism causing a vicious cycle between declining ATP and increasing ROS production and downregulation of NAD⁺ resulting in metabolic disturbance-mediated senescence of the HCEnCs. The excess ROS also impair DNA to activate the DNA damage response (DDR) pathway of ATM-p53-p21^WAF1/CIP1 with diminished poly(ADP-Ribose) polymerase (PARP) 1, a NAD⁺-dependent enzyme for DNA damage repair, resulting in cell cycle arrest and subsequent DDR-mediated senescence. Taken together, carteolol induces excess ROS to trigger HCEnC senescence via metabolic disturbance and DDR pathway.

Sodium selenite preserves rBM-MSCs' stemness, differentiation potential, and immunophenotype and protects them against oxidative stress via activation of the Nrf2 signaling pathway

BACKGROUND

The physiological level of reactive oxygen species (ROS) is necessary for many cellular functions. However, during the in-vitro manipulations, cells face a high level of ROS, leading to reduced cell quality. Preventing this abnormal ROS level is a challenging task. Hence, here we evaluated the effect of sodium selenite supplementation on the antioxidant potential, stemness capacity, and differentiation of rat-derived Bone Marrow MSCs (rBM-MSCs) and planned to check our hypothesis on the molecular pathways and networks linked to sodium selenite's antioxidant properties.

METHODS

MTT assay was used to assess the rBM-MSCs cells' viability following sodium selenite supplementation (concentrations of: 0.001, 0.01, 0.1, 1, 10 µM). The expression level of OCT-4, NANOG, and SIRT1 was explored using qPCR. The adipocyte differentiation capacity of MSCs was checked after Sodium Selenite treatment. The DCFH-DA assay was used to determine intracellular ROS levels. Sodium selenite-related expression of HIF-1α, GPX, SOD, TrxR, p-AKT, Nrf2, and p38 markers was determined using western blot. Significant findings were investigated by the String tool to picture the probable molecular network.

RESULTS

Media supplemented with 0.1 µM sodium selenite helped to preserve rBM-MSCs multipotency and keep their surface markers presentation; this also reduced the ROS level and improved the rBM-MSCs' antioxidant and stemness capacity. We observed enhanced viability and reduced senescence for rBM-MSCs. Moreover, sodium selenite helped in rBM-MSCs cytoprotection by regulating the expression of HIF-1 of AKT, Nrf2, SOD, GPX, and TrxR markers.

CONCLUSIONS

We showed that sodium selenite could help protect MSCs during in-vitro manipulations, probably via the Nrf2 pathway.

NOX4-derived ROS are neuroprotective by balancing intracellular calcium stores

Hyperexcitability is associated with neuronal dysfunction, cellular death, and consequently neurodegeneration. Redox disbalance can contribute to hyperexcitation and increased reactive oxygen species (ROS) levels are observed in various neurological diseases. NOX4 is an NADPH oxidase known to produce ROS and might have a regulating function during oxidative stress. We, therefore, aimed to determine the role of NOX4 on neuronal firing, hyperexcitability, and hyperexcitability-induced changes in neural network function. Using a multidimensional approach of an in vivo model of hyperexcitability, proteomic analysis, and cellular function analysis of ROS, mitochondrial integrity, and calcium levels, we demonstrate that NOX4 is neuroprotective by regulating ROS and calcium homeostasis and thereby preventing hyperexcitability and consequently neuronal death. These results implicate NOX4 as a potential redox regulator that is beneficial in hyperexcitability and thereby might have an important role in neurodegeneration.

An overlooked influence of reactive oxygen species on ammonia-oxidizing microbial communities in redox-fluctuating aquifers

Reactive oxygen species (ROS) are ubiquitous in O₂-perturbed aquifers, but their role in shaping ammonia-oxidizing microbial communities is not clear. This study examined the dynamic responses of ammonia-oxidizing microorganisms (AOMs) in redox-fluctuating aquifers to ROS via field investigation and in-lab verification using transcriptomes/ metatranscriptome and RT-qPCR. Ammonia-oxidizing archaea (AOA) dominated recharge aquifers with lower ROS levels, whereas ammonia-oxidizing bacteria (AOB) and heterotrophic nitrifying aerobic bacteria (HNB) predominated in discharge areas with higher ROS levels. Similar succession in AOM enrichments was found in that the dominant AOMs changed from AOA Nitrosopumilus to AOB Nitrosomonas with increasing ROS. Ammonia oxidation and antioxidant capacity differed significantly among three AOM isolates exposed to ROS. ROS decreased the amoA gene expression of AOA strain Nitrososphaera viennensis PLX03, accompanied by inhibited ammonia oxidation capacity. By contrast, the catalase and superoxide dismutase activities of the AOB strain Nitrosomonas oligotropha PLL12 and HNB strain Pseudomonas aeruginosa PLL01 increased, and the antioxidant genes katG, sodA, ahpC, and ahpF were significantly upregulated. These results demonstrate that ROS exert an important influence on AOMs in redox-fluctuating aquifers. This study improves our understanding of the ecological niches of AOMs in surface/subsurface environments.

Decoding algae under abnormal temperature variability with odorant as a responsive indicator

Harmful algal blooms impair the aesthetic quality and healthy performance of in-situ water. Worse yet, dramatic temperature variability arises additional difficulty in algal-induced risk assessment, which is so far poorly explored. Microcystis aeruginosa (FACHB 905), was selected to explore the odor-producing pattern (β-cyclocitral, the major odorant of the test alga) under several temperature-varying scenarios. Significant differences were observed in total β-cyclocitral yield between these scenarios, e.g., a rapid yield response as a result of acute temperature variation. Yield response was not only dependent on absolute temperature, but influenced by temperature variability stress. Acute increase (AI) or sequential increase (SI) in temperature caused extra production response, while the opposite was observed in groups with acute decrease (AD) and sequential decrease (SD) in temperature. Cell growth in AD group showed severe inhibition, with the specific growth rates fluctuating around half of that in 16-control. Whereas, SD could relieve such detrimental growth effects. Cell quota of β-cyclocitral yield was sensitive to temperature variation, with notable increase in AI and SI. Further, peaks in cell quota for SI group (79.3 %) were higher than for AI group (57.9 %). Cell quota variations in temperature-varying conditions contributed to the total yield response (R² = 0.566-0.980) more than cell intensity variations (R² = 0.0397-0.548). Further, it was also found that the internal mechanism by reactive oxygen species and pigments varied in various thermal scenarios. Overall, it was demonstrated that more than absolute value differences, temperature varying patterns across time influence algal behavior and related hazards, which should be noted in resource water quality management.

Ratiometric and colorimetric probes with large stokes shift for sensing of exogenous hypochlorite in potato sprouts and industrial effluents

Being one of the important reactive oxygen species (ROS), hypochlorite ions (ClO^-) are involved in the control of several pathological and physiological processes. However, overexpression of ClO^- may prompt several disorders including cancer. Therefore, two fluorescein functionalized compounds with catechol (probe 1) and 2-naphthyl (probe 2) as substituents were synthesized through Schiff base reaction to recognize ClO^- in food items and industrial samples. While probe 2 exhibited turn-off fluorescent response towards ClO^- with limit of detection (LOD) of 86.7 nM, structurally alike probe 1 showed excellent ratiometric response with low detection limit (36.3 nM), large Stokes shift (353 nm), and 'fast' response time (15 s). ¹H NMR titration experiments favored spiroring opening of probe 1 upon the reaction with ClO^-. Probe 1 was successfully utilized for the monitoring of exogenous ClO^- in industrial samples. Further, fabrication of probe coated fluorescent paper strips and recognition of ClO^- in sprouting potato show diverse practical applicability of our probes.

Diallyl trisulfide inhibits monosodium urate-induced NLRP3 inflammasome activation via NOX3/4-dependent mitochondrial oxidative stress in RAW 264.7 and bone marrow-derived macrophages

BACKGROUND

Monosodium urate (MSU) crystals are associated with gouty inflammatory diseases. MSU-associated inflammation is majorly triggered by NOD-like receptor protein 3 (NLRP3) inflammasome that promotes interleukin (IL)-1β secretion. Although diallyl trisulfide (DATS) is well-known polysulfide garlic compounds with anti-inflammatory effects, its action in MSU-induced inflammasome activation has not been known yet.

PURPOSE

The objective of the current study was to investigate anti-inflammasome effects and mechanisms of DATS in RAW 264.7 and bone marrow-derived macrophages (BMDM).

METHODS

The concentrations of IL-1β were analyzed with enzyme-linked immunosorbent assay. The MSU-induced mitochondrial damage and reactive oxygen species (ROS) production were detected by fluorescence microscope and flow cytometry. The protein expressions of NLRP3 signaling molecules, NADPH oxidase (NOX) 3/4 were assessed with Western blotting.

RESULTS

DATS suppressed MSU-induced IL-1β and caspase-1 accompanied by decreased inflammasome complex formation in RAW 264.7 and BMDM. In addition, DATS restored mitochondrial damage. DATS downregulated NOX 3/4 that were upregulated by MSU as predicted by gene microarray and confirmed by Western blotting.

CONCLUSION

This study first reports mechanistic finding that DATS alleviates MSU-induced NLRP3 inflammasome by mediating NOX3/4-dependent mitochondrial ROS production in macrophages in vitro and ex vivo, suggesting DATS could be effective therapeutic candidate for gouty inflammatory condition.

MITOCHONDRIA: The dual function of the transient receptor potential melastatin 2 channels from cytomembrane to mitochondria

Mitochondria are closely related to oxidative stress and play an important role in maintaining cell functional homeostasis and meeting cell energy demand. The transient receptor potential melastatin 2 (TRPM2) channel affects the occurrence and progression of diseases by regulating mitochondrial function. TRPM2 channel promotes Ca²⁺ influx to affect 18 kDa translocator protein (TSPO), mitochondrial membrane potential (MMP), reactive oxygen species (ROS), adenosine triphosphate (ATP) production, and mitochondrial autophagy. The mechanism of Ca²⁺ influx into the mitochondria by TRPM2 is abundant. Interestingly, the TRPM2 channel inhibits the production of mitochondrial ROS in cancer cells and promotes the production of mitochondrial ROS in normal cells, which induces cell death in normal cells but proliferation in cancer cells. TRPM2 can be a potential target for the treatment of various diseases due to its role as a molecular link between mitochondria and Ca²⁺ signals.

Antimicrobial particles based on Cu2ZnSnS4 monograins

In this research, Cu₂ZnSnS₄ (CZTS) particles were successfully fabricated via the molten salt approach from the copper, zinc and tin sulphides as raw precursors. SEM analysis revealed that CZTS particles are tetragonal-shaped with sharp edges, smooth flat plane morphology, and crystal size varying from 10.8 to 28.7 µm. The phase and crystalline structure of synthesized powders were investigated using XRD analysis, which confirms the presence of a tetragonal crystal structure kesterite phase. The chemical composition of CZTS particles was evaluated by EDX spectroscopy, which identified the nearly stoichiometric composition with an averaged formula of Cu_1.88Zn_1.04SnS_3.97. The TG/DTA-MS and ICP-OES analysis showed the possible decomposition pathways and predicted their degradation rate in aqueous solutions. The CZTS particles possessed highly effective concentration and time-dependent antimicrobial properties against medically relevant bacteria and yeast strains. The CZTS particles (1 g L^-1) exhibited over 95.7 ± 1.9% killing efficiency towards M. luteus. In contrast, higher dosages (3.5 and 5 g L^-1) led to its complete inactivation and reduced the P. aeruginosa cell viability to 43.2 ± 3.2% and 4.1 ± 1.1%, respectively. Moreover, the CZTS particles (0.5 g L^-1) are responsible for causing 54.8 ± 1.8% of C. krusei and 89.7 ± 2.1% of C. parapsilosis yeasts death within the 24 h of exposure, which expanded to almost 100% when yeasts were treated with two times higher CZTS concentration (1.0 g L^-1). The mechanism of action has been proposed and evidenced by monitoring the 2',7'-dichlorofluorescein (DCF) fluorescence, which revealed that the overproduction of reactive oxygen species (ROS) is responsible for microorganism death.

STAT3 signaling promotes cardiac injury by upregulating NCOA4-mediated ferritinophagy and ferroptosis in high-fat-diet fed mice

High-fat diet (HFD) intake provokes obesity and cardiac anomalies. Recent studies have found that ferroptosis plays a role in HFD-induced cardiac injury, but the underlying mechanism is largely unclear. Ferritinophagy is an important part of ferroptosis that is regulated by nuclear receptor coactivator 4 (NCOA4). However, the relationship between ferritinophagy and HFD-induced cardiac damage has not been explored. In this study, we found that oleic acid/palmitic acid (OA/PA) increased the level of ferroptotic events including iron and ROS accumulation, upregulation of PTGS2 mRNA and protein levels, reduced SOD and GSH levels, and significant mitochondrial damage in H9C2 cells, which could be reversed by the ferroptosis inhibitor ferrostatin-1 (Fer-1). Intriguingly, we found that the autophagy inhibitor 3-methyladenine mitigated OA/PA-induced ferritin downregulation, iron overload and ferroptosis. OA/PA increased the protein level of NCOA4. Knockdown of NCOA4 by SiRNA partly reversed the reduction in ferritin, mitigated iron overload and lipid peroxidation, and subsequently alleviated OA/PA-induced cell death, indicating that NCOA4-mediated ferritinophagy was required for OA/PA-induced ferroptosis. Furthermore, we demonstrated that NCOA4 was regulated by IL-6/STAT3 signaling. Inhibition or knockdown of STAT3 effectively reduced NCOA4 levels to protect H9C2 cells from ferritinophagy-mediated ferroptosis, whereas STAT3 overexpression by plasmid appeared to increase NCOA4 expression and contribute to classical ferroptotic events. Consistently, phosphorylated STAT3 upregulation, ferritinophagy activation, and ferroptosis induction also occurred in HFD-fed mice and were responsible for HFD-induced cardiac injury. In addition, we found evidence that piperlongumine, a natural compound, effectively reduced phosphorylated STAT3 levels to protect cardiomyocytes from ferritinophagy-mediated ferroptosis both in vitro and in vivo. Based on these findings, we concluded that ferritinophagy-mediated ferroptosis was one of the critical mechanisms contributing to HFD-induced cardiac injury. The STAT3/NCOA4/FTH1 axis might be a novel therapeutic target for the treatment of HFD-induced cardiac injury.

AAZ2 induces mitochondrial-dependent apoptosis by targeting PDK1 in gastric cancer

Drastic surges in intracellular reactive oxygen species (ROS) induce cell apoptosis, while most chemotherapy drugs lead to the accumulation of ROS. Here, we constructed an organic compound, arsenical N-‍(4-(1,3,2-dithiarsinan-2-yl)phenyl)acrylamide (AAZ2), which could prompt the ROS to trigger mitochondrial-dependent apoptosis in gastric cancer (GC). Mechanistically, by targeting pyruvate dehydrogenase kinase 1 (PDK1), AAZ2 caused metabolism alteration and the imbalance of redox homeostasis, followed by the inhibition of phosphoinositide-3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway and leading to the activation of B-cell lymphoma 2 (Bcl2)/Bcl2-associated X (Bax)/caspase-9 (Cas9)/Cas3 cascades. Importantly, our in vivo data demonstrated that AAZ2 could inhibit the growth of GC xenograft. Overall, our data suggested that AAZ2 could contribute to metabolic abnormalities, leading to mitochondrial-dependent apoptosis by targeting PDK1 in GC.

Kai-Xin-San protects against mitochondrial dysfunction in Alzheimer's disease through SIRT3/NLRP3 pathway

BACKGROUND

Kai-Xin-San (KXS) has been reported to have a good curative impact on dementia. The purpose of the study was to determine whether KXS might ameliorate cognitive deficits in APP/PS1 mice and to evaluate its neuroprotective mechanism.

METHODS

APP/PS1 mice were employed as an AD animal model; Aβ_1-42 and KXS-containing serum were used in HT22 cells. Four different behavioral tests were used to determine the cognitive ability of mice. Nissl staining was utilized to detect hippocampal neuron changes. ROS, SOD, and MDA were used to detect oxidative stress levels. Transmission electron microscopy and Western blot were used to evaluate mitochondrial morphology, mitochondrial division, and fusion state. Western blotting and immunofluorescence identified PSD95, BDNF, NGF, SYN, SIRT3, and NLRP3 inflammasome levels.

RESULTS

The results indicated that KXS protected APP/PS1 mice against cognitive impairments. KXS suppressed neuronal apoptosis and oxidative stress among APP/PS1 mice. KXS and KXS-containing serum improved mitochondrial dysfunction and synaptic and neurotrophic factors regarding APP/PS1 mice. In addition, KXS and KXS-containing serum enhanced mitochondrial SIRT3 expression and reduced NLRP3 inflammasome expression in APP/PS1 mice.

CONCLUSION

KXS improves cognitive dysfunction among APP/PS1 mice via regulating SIRT3-mediated neuronal cell apoptosis. These results suggested that KXS was proposed as a neuroprotective agent for AD progression.