The ROS scavenger, NAC, regulates hepatic Vα14iNKT cells signaling during Fas mAb-dependent fulminant liver failure

Liver ischemia reperfusion injury: Mechanisms, cellular pathways, and therapeutic approaches

Liver ischemia-reperfusion injury (LIRI) is a critical challenge in liver transplantation, resection, and trauma surgeries, leading to significant hepatic damage due to oxidative stress, inflammation, and mitochondrial dysfunction. This review explores the cellular and molecular mechanisms underlying LIRI, focusing on ATP depletion, mitochondrial dysfunction, and the involvement of reactive oxygen species (ROS). Inflammatory pathways, including the activation of nuclear factor-kappa B (NF-κB) and the NLRP3 inflammasome, as well as pro-inflammatory cytokines such as TNF-α and IL-1β, play a crucial role in exacerbating tissue damage. Various types of cell death, including necrosis, apoptosis, necroptosis, pyroptosis, ferroptosis and cuproptosis are also discussed. Therapeutic interventions targeting these mechanisms, such as antioxidants, anti-inflammatories, mitochondrial protectors, and signaling modulators, have shown promise in pre-clinical studies. However, translating these findings into clinical practice faces challenges due to the limitations of animal models and the complexity of human responses. Emerging therapies, such as RNA-based treatments, genetic editing, and stem cell therapies, offer potential breakthroughs in LIRI management. This review highlights the need for further research and the development of innovative therapeutic approaches to improve clinical outcomes.

Hepatocellular carcinoma cells downregulate NADH:Ubiquinone Oxidoreductase Subunit B3 to maintain reactive oxygen species homeostasis

BACKGROUND

HCC is a leading cause of cancer-related death. The role of reactive oxygen species (ROS) in HCC remains elusive. Since a primary ROS source is the mitochondrial electron transport chain complex Ι and the NADH:ubiquinone Oxidoreductase Subunit B3 (NDUFB3), a complex I subunit, is critical for complex I assembly and regulates the associated ROS production, we hypothesize that some HCCs progress by hijacking NDUFB3 to maintain ROS homeostasis.

METHODS

NDUFB3 in human HCC lines was either knocked down or overexpressed. The cells were then analyzed in vitro for proliferation, migration, invasiveness, colony formation, complex I activity, ROS production, oxygen consumption, apoptosis, and cell cycle. In addition, the in vivo growth of the cells was evaluated in nude mice. Moreover, the role of ROS in the NDUFB3-mediated changes in the HCC lines was determined using cellular and mitochondrion-targeted ROS scavengers.

RESULTS

HCC tissues showed reduced NDUFB3 protein expression compared to adjacent healthy tissues. In addition, NDUFB3 knockdown promoted, while its overexpression suppressed, HCC cells' growth, migration, and invasiveness. Moreover, NDUFB3 knockdown significantly decreased, whereas its overexpression increased complex I activity. Further studies revealed that NDUFB3 overexpression elevated mitochondrial ROS production, causing cell apoptosis, as manifested by the enhanced expressions of proapoptotic molecules and the suppressed expression of the antiapoptotic molecule B cell lymphoma 2. Finally, our data demonstrated that the apoptosis was due to the activation of the c-Jun N-terminal kinase (JNK) signaling pathway and cell cycle arrest at G0/G1 phase.

CONCLUSIONS

Because ROS plays essential roles in many biological processes, such as aging and cancers, our findings suggest that NDFUB3 can be targeted for treating HCC and other human diseases.

Characterization of a Zeolite-Y-Encapsulated Zn(II)Salmphen Complex with Targeted Anticancer Property

Resistance and severe side effects of classical chemotherapeutic drugs are major challenges to cancer therapy. New therapeutic agents and combination therapy are considered potential solutions that enhance the efficacy of the drug as well as reduce drug resistance. The success of a platinum-based anticancer drug, cisplatin, has paved the way to explore metal-centered anticancer therapeutic agents. Herein, the zeolite-Y-encapsulated Zn(II)Salmphen complex is synthesized using a flexible ligand approach. The Zn(II)Salmphen complex and its encapsulation within the supercage of zeolite-Y were characterized by elemental analysis, Fourier transform infrared (FTIR) spectroscopy, UV-vis, fluorescence, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), NMR, and high-resolution mass spectrometry (HRMS) techniques. Elemental analysis, PXRD, and SEM, all together confirm the integrity of the zeolite framework after the encapsulation of Zn(II)Salmphen complex in it, and elemental analysis provides the Si/Al ratio and Zn content present. FTIR and XPS studies indicate the successful encapsulation of the complex. NMR and HRMS studies confirm that the Zn(II)Salmphen complex is dimer; however, within the supercage of zeolite-Y, it is expected to exist as a monomer. The extent of structural modification of the encapsulated Zn(II)Salmphen complex is intimated by electronic spectroscopic studies. The free-state Zn(II)Salmphen is a fluorescent complex, and even the encapsulated Zn(II)Salmphen complex, when taken in dimethyl sulfoxide (DMSO), shows fluorescence. In comparison to cisplatin, encapsulated Zn(II)Salmphen complex displays comparable cytotoxicity (IC50 = 2.0 ± 0.5 μg/mL at 48 h) toward breast cancer cell line, whereas free Zn(II)Salmphen has better cytotoxicity (IC50 = 1.5 ± 0.5 μg/mL at 48 h). Importantly, elemental analysis has revealed that the IC50 value, if calculated only in terms of Zn(II)Salmphen within Zn(II)Salmphen-Y, is as low as 54.59 ng/mL, indicating a very high efficacy of the drug. Interestingly, a 48 h treatment with the encapsulated Zn(II)Salmphen complex shows no toxicity toward immortal noncancerous keratinocyte cells (HaCaT), whereas cisplatin has an IC50 value of 1.75 ± 0.5 μg/mL. Internalization studies indicate that zeolite-Y targets cancer cells better than it does noncancerous ones. Hence, cellular uptake of the zeolite-encapsulated Zn(II)Salmphen complex in cancer cells is more than that in HaCaT cells, resulting in the generation of more reactive oxygen species and cell death. Significant upregulation of DNA damage response protein indicates that DNA-damage-induced cellular apoptosis could be the mechanism of drug action. Overall, the zeolite-encapsulated Zn(II)Salmphen complex could be a better alternative to the traditional drug cisplatin with minimal effect on noncancerous HaCaT cells and can also be utilized as a fluorescent probe in exploring the mechanistic pathway of its activity against cancer cells.

S100A9 Derived from Chemoembolization-Induced Hypoxia Governs Mitochondrial Function in Hepatocellular Carcinoma Progression

Transarterial chemoembolization (TACE) is the major treatment for advanced hepatocellular carcinoma (HCC), but it may cause hypoxic environment, leading to rapid progression after treatment. Here, using high-throughput sequencing on different models, S100 calcium binding protein A9 (S100A9) is identified as a key oncogene involved in post-TACE progression. Depletion or pharmacologic inhibition of S100A9 significantly dampens the growth and metastatic ability of HCC. Mechanistically, TACE induces S100A9 via hypoxia-inducible factor 1α (HIF1A)-mediated pathway. S100A9 acts as a scaffold recruiting ubiquitin specific peptidase 10 and phosphoglycerate mutase family member 5 (PGAM5) to form a tripolymer, causing the deubiquitination and stabilization of PGAM5, leading to mitochondrial fission and reactive oxygen species production, thereby promoting the growth and metastasis of HCC. Higher S100A9 level in HCC tissue or in serum predicts a worse outcome for HCC patients. Collectively, this study identifies S100A9 as a key driver for post-TACE HCC progression. Targeting S100A9 may be a promising therapeutic strategy for HCC patients.

Fructose Induces Pulmonary Fibrotic Phenotype Through Promoting Epithelial-Mesenchymal Transition Mediated by ROS-Activated Latent TGF-β1

Fructose is a commonly used food additive and has many adverse effects on human health, but it is unclear whether fructose impacts pulmonary fibrosis. TGF-β1, a potent fibrotic inducer, is produced as latent complexes by various cells, including alveolar epithelial cells, macrophages, and fibroblasts, and must be activated by many factors such as reactive oxygen species (ROS). This study explored the impact of fructose on pulmonary fibrotic phenotype and epithelial-mesenchymal transition (EMT) using lung epithelial cells (A549 or BEAS-2B) and the underlying mechanisms. Fructose promoted the cell viability of lung epithelial cells, while N-Acetyl-l-cysteine (NAC) inhibited such. Co-treatment of fructose and latent TGF-β1 could induce the fibrosis phenotype and the epithelial-mesenchymal transition (EMT)-related protein expression, increasing lung epithelial cell migration and invasion. Mechanism analysis shows that fructose dose-dependently promoted the production of total and mitochondrial ROS in A549 cells, while NAC eliminated this promotion. Notably, post-administration with NAC or SB431542 (a potent TGF-β type I receptor inhibitor) inhibited fibrosis phenotype and EMT process of lung epithelial cells co-treated with fructose and latent TGF-β1. Finally, the fibrosis phenotype and EMT-related protein expression of lung epithelial cells were mediated by the ROS-activated latent TGF-β1/Smad3 signal. This study revealed that high fructose promoted the fibrotic phenotype of human lung epithelial cells by up-regulating oxidative stress, which enabled the latent form of TGF-β1 into activated TGF-β1, which provides help and reference for the diet adjustment of healthy people and patients with fibrosis.

Oral N-acetylcysteine decreases IFN-γ production and ameliorates ischemia-reperfusion injury in steatotic livers

Type 1 Natural Killer T-cells (NKT1 cells) play a critical role in mediating hepatic ischemia-reperfusion injury (IRI). Although hepatic steatosis is a major risk factor for preservation type injury, how NKT cells impact this is understudied. Given NKT1 cell activation by phospholipid ligands recognized presented by CD1d, we hypothesized that NKT1 cells are key modulators of hepatic IRI because of the increased frequency of activating ligands in the setting of hepatic steatosis. We first demonstrate that IRI is exacerbated by a high-fat diet (HFD) in experimental murine models of warm partial ischemia. This is evident in the evaluation of ALT levels and Phasor-Fluorescence Lifetime (Phasor-FLIM) Imaging for glycolytic stress. Polychromatic flow cytometry identified pronounced increases in CD45+CD3+NK1.1+NKT1 cells in HFD fed mice when compared to mice fed a normal diet (ND). This observation is further extended to IRI, measuring ex vivo cytokine expression in the HFD and ND. Much higher interferon-gamma (IFN-γ) expression is noted in the HFD mice after IRI. We further tested our hypothesis by performing a lipidomic analysis of hepatic tissue and compared this to Phasor-FLIM imaging using "long lifetime species", a byproduct of lipid oxidation. There are higher levels of triacylglycerols and phospholipids in HFD mice. Since N-acetylcysteine (NAC) is able to limit hepatic steatosis, we tested how oral NAC supplementation in HFD mice impacted IRI. Interestingly, oral NAC supplementation in HFD mice results in improved hepatic enhancement using contrast-enhanced magnetic resonance imaging (MRI) compared to HFD control mice and normalization of glycolysis demonstrated by Phasor-FLIM imaging. This correlated with improved biochemical serum levels and a decrease in IFN-γ expression at a tissue level and from CD45+CD3+CD1d+ cells. Lipidomic evaluation of tissue in the HFD+NAC mice demonstrated a drastic decrease in triacylglycerol, suggesting downregulation of the PPAR-γ pathway.

KCl-CaCO3 nanoclusters armoured with Pt nanocrystals for enhanced electro-driven tumor inhibition

Electrodynamic therapy (EDT) has recently emerged as an alternative approach for tumor therapy via the generation of ROS by platinum (Pt) nanoparticles under electric field. An interesting phenomenon observed during EDT is that the increased on-site concentration of chloride ions is highly beneficial for ROS generation and inhibition efficacy. Here, in this study, nanoclusters (KCC), consisting of potassium chloride (KCl) nanocrystals and amorphous calcium carbonate (CaCO₃), were synthesized and integrated with platinum nanoparticles (KCCP). In this system, KCC can dissolve and release calcium and chloride ions within tumor cells. The intracellular chloride ions considerably facilitated ROS generation by Pt nanoparticles under an electric field. More importantly, the excessive calcium ions and ROS formed a cycle of mutual promotion and self-amplification in cells, leading to agitated tumor inhibition, both in vitro and in vivo.

Enhanced pyrazolopyrimidinones cytotoxicity against glioblastoma cells activated by ROS-Generating cold atmospheric plasma

Pyrazolopyrimidinones are fused nitrogen-containing heterocyclic systems, which act as a core scaffold in many pharmaceutically relevant compounds. Pyrazolopyrimidinones have been demonstrated to be efficient in treating several diseases, including cystic fibrosis, obesity, viral infection and cancer. In this study using glioblastoma U-251MG cell line, we tested the cytotoxic effects of 15 pyrazolopyrimidinones, synthesised via a two-step process, in combination with cold atmospheric plasma (CAP). CAP is an adjustable source of reactive oxygen and nitrogen species as well as other unique chemical and physical effects which has been successfully tested as an innovative cancer therapy in clinical trials. Significantly variable cytotoxicity was observed with IC₅₀ values ranging from around 11 μM to negligible toxicity among tested compounds. Interestingly, two pyrazolopyrimidinones were identified that act in a prodrug fashion and display around 5-15 times enhanced reactive-species dependent cytotoxicity when combined with cold atmospheric plasma. Activation was evident for direct CAP treatment on U-251MG cells loaded with the pyrazolopyrimidinone and indirect CAP treatment of the pyrazolopyrimidinone in media before adding to cells. Our results demonstrated the potential of CAP combined with pyrazolopyrimidinones as a programmable cytotoxic therapy and provide screened scaffolds that can be used for further development of pyrazolopyrimidinone prodrug derivatives.

Knockdown of Dual Oxidase 1 (DUOX1) Promotes Wound Healing by Regulating Reactive Oxygen Species (ROS) by Activation of Nuclear Kactor kappa B (NF-κB) Signaling

Background

The aim of this study was to evaluate the potential role of dual oxidase 1 (DUOX1) in wound healing.

Material/Methods

Primary fibroblasts were isolated from wound granulation tissue. Fibroblasts cell lines were established using DUOX1 overexpression and interference. Cell proliferation and reactive oxygen species (ROS) production were measured and compared among the groups.

Results

DUOX1 expression was highest in the slow-healing tissues (P<0.05). Knockdown of DUOX1 significantly increased cell proliferation and inhibited ROS production and cell apoptosis (P<0.01). Moreover, expression of malondialdehyde (MDA) was significantly reduced, while expression of superoxide dismutase (SOD) expression was significantly increased (P<0.01). In addition, DUOX1 silencing significantly upregulated collagen I, collagen III, and NF-κB protein levels in the cytoplasm, and inhibited the protein levels of P21, P16, and NF-κB in the nucleus (P<0.01). Overexpression of DUOX1 caused a reverse reaction mediated by knockdown of DUOX1. When DUOX1-overexpressing cells were treated with the ROS inhibitor N-acetyl-L-cysteine (NAC), the protein levels that were increased by DUOX1 overexpression were reversed.

Conclusions

These results suggest that knockdown of DUOX1 significantly benefits wound healing, likely by the regulation of oxidative stress via NF-κB pathway activation.

Icariin Alleviates IL-1β-Induced Matrix Degradation By Activating The Nrf2/ARE Pathway In Human Chondrocytes

Objective

Osteoarthritis (OA) is characterized by progressive matrix destruction of articular cartilage. This study aimed to investigate the potential antioxidative and chondroprotective effects and underlying mechanism of Icariin (ICA) in interleukin-1 beta (IL-1β)-induced extracellular matrix (ECM) degradation of OA cartilage.

Methods

Human chondrocyte cell line HC-A was treated with different doses of ICA, and then MTT assay and PI staining were used to estimate ICA-induced chondrocyte apoptosis. Intracellular ROS and superoxide dismutase (SOD) and glutathione peroxidase (GPX) were measured after treatment by IL-1β with or without ICA. The mRNA and protein expression levels of redox transcription factor Nrf2 and the downstream effector SOD-1, SOD-2, NQO-1 and HO-1 were assayed to explore the detailed mechanism by which ICA alleviates ECM degradation. Finally, to expound the role of Nrf2 in ICA-mediated chondroprotection, we specifically depleted Nrf2 in human chondrocytes and then pretreated them with ICA followed by IL-1β.

Results

ICA had no cytotoxic effects on human chondrocytes and 10⁻⁹ M was selected as the optimum concentration. ROS induced by IL-1β could drastically activate matrix-degrading proteases and ICA could significantly rescue the matrix degradation and excess ROS generation caused by IL-1β. We observed that ICA activated the Nrf2/ARE pathway, consequently upregulating the generation of GPX and SOD. Ablation of Nrf2 abrogated the chondroprotective and antioxidative effects of ICA in IL-1β-treated chondrocytes.

Conclusion

ICA alleviates IL-1β-induced matrix degradation and eliminates ROS by activating the Nrf2/ARE pathway.

MARCH5 overexpression contributes to tumor growth and metastasis and associates with poor survival in breast cancer

Background

Human MARCH5 is a mitochondrial localized E3 ubiquitin-protein ligase that is critical for the regulation of mitochondrial dynamics. A body of evidence has indicated the close links between unbalanced mitochondrial dynamics and cancers. However, the expression, biological functions, and prognostic significance of MARCH5 in breast cancer (BC) have not been determined.

Materials and methods

The mRNA and protein expressions of MARCH5 were evaluated by quantitative real-time PCR and Western blot analysis in BC cell lines and tumor tissues. Clinical prognostic significance of MARCH5 was assessed in 65 patients with BC. The biological functions of MARCH5 were determined by in vitro cell proliferation, apoptosis, cell cycle, migration and invasion assays, and in vivo tumor growth and metastasis assays through knockdown or overexpression of MARCH5 in BC cells. In addition, the underlying mechanisms by which MARCH5 regulated BC cell growth and metastasis were explored.

Results

MARCH5 was substantially upregulated in BC cells mainly due to the downregulation of miR-30a, which contributed to the poor survival of BC patients. MARCH5 promoted the growth and metastasis of BC cells both in vitro and in vivo by inducing G1-S cell cycle arrest and epithelial-mesenchymal transition. Mechanistic investigations revealed that the oncogenic effect of MARCH5 was mainly mediated by increased mitochondrial fission and subsequent ROS production in BC cells.

Conclusion

Our findings demonstrate that MARCH5 plays a critical oncogenic role in BC cells, which provides experimental evidence supporting MARCH5 as a potential therapeutic target in BC therapy.

Activation of natural killer T cells contributes to triptolide-induced liver injury in mice

Triptolide (TP) is the main active ingredient of Tripterygium wilfordii Hook.f, which has attracted great interest due to its promising efficacy for autoimmune diseases and tumors. However, severe adverse reactions, especially hepatotoxicity, have restricted its approval in the market. In the present study we explored the role of hepatic natural killer T (NKT) cells in the pathogenesis of TP-induced liver injury in mice. TP (600 μg/kg/day, i.g.) was administered to female mice for 1, 3, or 5 days. We found that administration of TP dose-dependently induced hepatotoxicity, evidenced by the body weight reduction, elevated serum ALT and AST levels, as well as significant histopathological changes in the livers. However, the mice were resistant to the development of TP-induced liver injury when their NKT cells were depleted by injection of anti-NK1.1 mAb (200 μg, i.p.) on days -2 and -1 before TP administration. We further revealed that TP administration activated NKT cells, dominantly releasing Th1 cytokine IFN-γ, recruiting neutrophils and macrophages, and leading to liver damage. After anti-NK1.1 injection, however, the mice mainly secreted Th2 cytokine IL-4 in the livers and exhibited a significantly lower percentage of hepatic infiltrating neutrophils and macrophages upon TP challenge. The activation of NKT cells was associated with the upregulation of Toll-like receptor (TLR) signaling pathway. Collectively, these results demonstrate a novel role of NKT cells contributing to the mechanisms of TP-induced liver injury. More importantly, the regulation of NKT cells may promote effective measures that control drug-induced liver injury.

MTP18 overexpression contributes to tumor growth and metastasis and associates with poor survival in hepatocellular carcinoma

Background

Human MTP18 (mitochondrial protein 18 kDa) is a novel nuclear-encoded mitochondrial membrane protein that is involved in controlling mitochondrial fission. Our bioinformatic analysis of TCGA data revealed an aberrant overexpression of MTP18 in hepatocellular carcinoma (HCC). We analyzed its biological effects and prognostic significance in this malignancy.

Methods

MTP18 expression was evaluated by qRT-PCR and western blot analysis in 20 paired tumor and peritumor tissues. Clinical impact of MTP18 overexpression was assessed in 156 patients with HCC. The effects of MTP18 knockdown or overexpression on cell growth and metastasis were determined by cell proliferation, colony formation, cell cycle, apoptosis, migration, and invasion assays. Furthermore, the underlying molecular mechanisms by which MTP18 overexpression promoted HCC cell growth and metastasis were explored.

Results

MTP18 was commonly overexpressed in HCC tissues mainly due to the downregulation of miR-125b, which significantly contributed to poor prognosis of HCC patients. Functional experiments revealed that MTP18 promoted both the growth and metastasis of HCC cells by inducing the progression of cell cycle, epithelial to mesenchymal transition (EMT) and production of MMP–9, and suppressing cell apoptosis. Mechanistically, increased mitochondrial fission and subsequent ROS production was found to be involved in the promotion of growth and metastasis by MTP18 in HCC cells.

Conclusions

MTP18 plays a pivotal oncogenic role in hepatocellular carcinogenesis; its overexpression may serve as a novel prognostic factor and a therapeutic target in HCC.

O2-3-Aminopropyl diazeniumdiolates suppress the progression of highly metastatic triple-negative breast cancer by inhibition of microvesicle formation via nitric oxide-based epigenetic regulation

Currently, there is no effective therapy for the treatment of highly metastatic triple-negative breast cancer (TNBC). Microvesicle (MV) formation is crucial for the metastasis of TNBC. Here we report a novel strategy to inhibit the generation of MVs for the intervention of TNBC. O²-3-Aminopropyl diazeniumdiolates 3a-f are designed and synthesized, which can be activated by lysyloxidase over-expressed in TNBC cells. The most active compound 3f is able to selectively release high levels of NO in TNBC cells, inhibit the cell proliferation, and reduce the adhesion, invasion and migration of TNBC cells in vitro. Furthermore, 3f significantly suppresses the growth and metastasis of implanted TNBC in vivo through attenuating MV formation by an epigenetic modification of miR-203/RAB22A expression in an NO-dependent manner, providing the first evidence of NO donor(s) acting as epigenetic modulators to fight highly metastatic TNBC.

Activation of autophagy by stress-activated signals as a cellular self-defense mechanism against the cytotoxic effects of MBIC in human breast cancer cells in vitro

We recently reported that methyl 2-(-5-fluoro-2-hydroxyphenyl)-1H-benzo[d]imidazole-5-carboxylate (MBIC) is a microtubule targeting agent (MTA) with multiple mechanisms of action including apoptosis in two human breast cancer cell-lines MCF-7 and MDA-MB-231. In the present study, investigation of early molecular events following MBIC treatment demonstrated the induction of autophagy. This early (<24 h) response to MBIC was characterized by accumulation of autophagy markers; LC3-II, Beclin1, autophagic proteins (ATGs) and collection of autophagosomes but with different variations in the two cell-lines. MBIC-induced autophagy was associated with generation of reactive oxygen species (ROS). In parallel, an increased activation of SAPK/JNK pathway was detected, as an intersection of ROS production and induction of autophagy. The cytotoxic effect of MBIC was enhanced by inhibition of autophagy through blockage of SAPK/JNK signaling, suggesting that MBIC-induced autophagy, is a possible cellular self-defense mechanism against toxicity of this agent in both breast cancer cell-lines. The present findings suggest that inhibition of autophagy eliminates the cytoprotective activity of MDA-MB-231 and MCF-7 cells, and sensitizes both the aggressive and non-aggressive human breast cancer cell-lines to the cytotoxic effects of MBIC.

Silibinin protects Staphylococcus aureus from UVC-induced bactericide via enhanced generation of reactive oxygen species

ROS produced by silibinin suppresses UVC-inducedStaphylococcus aureuscell death.

Non-Thermal Atmospheric Pressure Plasma Efficiently Promotes the Proliferation of Adipose Tissue-Derived Stem Cells by Activating NO-Response Pathways

Non-thermal atmospheric pressure plasma (NTAPP) is defined as a partially ionized gas with electrically charged particles at atmospheric pressure. Our study showed that exposure to NTAPP generated in a helium-based dielectric barrier discharge (DBD) device increased the proliferation of adipose tissue-derived stem cells (ASCs) by 1.57-fold on an average, compared with untreated cells at 72 h after initial NTAPP exposure. NTAPP-exposed ASCs maintained their stemness, capability to differentiate into adipocytes but did not show cellular senescence. Therefore, we suggested that NTAPP can be used to increase the proliferation of ASCs without affecting their stem cell properties. When ASCs were exposed to NTAPP in the presence of a nitric oxide (NO) scavenger, the proliferation-enhancing effect of NTAPP was not obvious. Meanwhile, the proliferation of NTAPP-exposed ASCs was not much changed in the presence of scavengers for reactive oxygen species (ROS). Also, Akt, ERK1/2, and NF-κB were activated in ASCs after NTAPP exposure. These results demonstrated that NO rather than ROS is responsible for the enhanced proliferation of ASCs following NTAPP exposure. Taken together, this study suggests that NTAPP would be an efficient tool for use in the medical application of ASCs both in vitro and in vivo.

Activation of autophagy by FOXO3 regulates redox homeostasis during osteogenic differentiation

Bone remodeling is a continuous physiological process that requires constant generation of new osteoblasts from mesenchymal stem cells (MSCs). Differentiation of MSCs to osteoblast requires a metabolic switch from glycolysis to increased mitochondrial respiration to ensure the sufficient energy supply to complete this process. As a consequence of this increased mitochondrial metabolism, the levels of endogenous reactive oxygen species (ROS) rise. In the current study we analyzed the role of forkhead box O3 (FOXO3) in the control of ROS levels in human MSCs (hMSCs) during osteogenic differentiation. Treatment of hMSCs with H₂O₂ induced FOXO3 phosphorylation at Ser294 and nuclear translocation. This ROS-mediated activation of FOXO3 was dependent on mitogen-activated protein kinase 8 (MAPK8/JNK) activity. Upon FOXO3 downregulation, osteoblastic differentiation was impaired and hMSCs lost their ability to control elevated ROS levels. Our results also demonstrate that in response to elevated ROS levels, FOXO3 induces autophagy in hMSCs. In line with this, impairment of autophagy by autophagy-related 7 (ATG7) knockdown resulted in a reduced capacity of hMSCs to regulate elevated ROS levels, together with a reduced osteoblast differentiation. Taken together our findings are consistent with a model where in hMSCs, FOXO3 is required to induce autophagy and thereby reduce elevated ROS levels resulting from the increased mitochondrial respiration during osteoblast differentiation. These new molecular insights provide an important contribution to our better understanding of bone physiology.

Intracellular ROS mediates gas plasma-facilitated cellular transfection in 2D and 3D cultures

This study reports the potential of cold atmospheric plasma (CAP) as a versatile tool for delivering oligonucleotides into mammalian cells. Compared to lipofection and electroporation methods, plasma transfection showed a better uptake efficiency and less cell death in the transfection of oligonucleotides. We demonstrated that the level of extracellular aqueous reactive oxygen species (ROS) produced by gas plasma is correlated with the uptake efficiency and that this is achieved through an increase of intracellular ROS levels and the resulting increase in cell membrane permeability. This finding was supported by the use of ROS scavengers, which reduced CAP-based uptake efficiency. In addition, we found that cold atmospheric plasma could transfer oligonucleotides such as siRNA and miRNA into cells even in 3D cultures, thus suggesting the potential for unique applications of CAP beyond those provided by standard transfection techniques. Together, our results suggest that cold plasma might provide an efficient technique for the delivery of siRNA and miRNA in 2D and 3D culture models.

Sublethal vancomycin-induced ROS mediating antibiotic resistance in Staphylococcus aureus

S. aureus may cause many human infectious diseases, which is well-known for the quickly developed drug resistance. Reports have shown that oxidative stress connects with bactericidal antibiotics. Our results exhibit that at least induced ROS may be beneficial to vancomycin resistance in two strains of hVRSA. The present findings help to recover novel insights into the relationships between oxidative stress and bacterial resistance, which has important implications for further use of antibiotics and development of therapeutics strategies for hVRSA.

Staphylococcus aureus is the leading cause of many human infectious diseases. Besides infectious dangers, S. aureus is well-known for the quickly developed drug resistance. Although great efforts have been made, mechanisms underlying the antibiotic effects of S. aureus are still not well clarified. Recently, reports have shown that oxidative stress connects with bactericidal antibiotics [Dwyer et al. (2009) Curr. Opin. Microbiol. 12, 482–489]. Based on this point, we demonstrate that reactive oxygen species (ROS) induced by sublethal vancomycin may be partly responsible for the antibiotic resistance in heterogeneous vancomycin resistant S. aureus (hVRSA). Sublethal vancomycin treatment may induce protective ROS productions in hVRSA, whereas reduction in ROS level in hVRSA strains may increase their vancomycin susceptibility. Moreover, low dose of ROS in VSSA (vancomycin susceptible S. aureus) strains may promote their survival under vancomycin conditions. Our findings reveal that modest ROS generation may be protective for vancomycin resistance in hVRSA. These results recover novel insights into the relationship between oxidative stress and bacterial resistance, which has important applications for further use of antibiotics and development of therapeutics strategies for hVRSA.

Gambogic Acid lysinate induces apoptosis in breast cancer mcf-7 cells by increasing reactive oxygen species

Gambogic acid (GA) inhibits the proliferation of various human cancer cells. However, because of its water insolubility, the antitumor efficacy of GA is limited. Objectives. To investigate the antitumor activity of gambogic acid lysinate (GAL) and its mechanism. Methods. Inhibition of cell proliferation was determined by MTT assay; intracellular ROS level was detected by staining cells with DCFH-DA; cell apoptosis was determined by flow cytometer and the mechanism of GAL was investigated by Western blot. Results. GAL inhibited the proliferation of MCF-7 cells with IC₅₀ values 1.46 μmol/L comparable with GA (IC₅₀, 1.16 μmol/L). GAL promoted the production of ROS; however NAC could remove ROS and block the effect of GAL. GAL inhibited the expression of SIRT1 but increased the phosphorylation of FOXO3a and the expression of p27Kip1. At knockdown of FOXO3a, cell apoptosis induced by GAL can be partly blocked. In addition it also enhanced the cleavage of caspase-3. Conclusions. GAL inhibited MCF-7 cell proliferation and induced MCF-7 cell apoptosis by increasing ROS level which could induce cell apoptosis by both SIRT1/FOXO3a/p27Kip1 and caspase-3 signal pathway. These results suggested that GAL might be useful as a modulation agent in cancer chemotherapy.

In vivo siRNA delivery of Keap1 modulates death and survival signaling pathways and attenuates concanavalin-A-induced acute liver injury in mice

Oxidative stress contributes to the progression of acute liver failure (ALF). Transcription factor nuclear factor-erythroid 2-related factor (Nrf2) serves as an endogenous regulator by which cells combat oxidative stress. We have investigated liver damage and the balance between death and survival signaling pathways in concanavalin A (ConA)-mediated ALF using in vivo siRNA delivery targeting Keap1 in hepatocytes. For that goal, mice were injected with Keap1- or luciferase-siRNA-containing liposomes via the tail vein. After 48 hours, ALF was induced by ConA. Liver histology, pro-inflammatory mediators, antioxidant responses, cellular death, and stress and survival signaling were assessed. Keap1 mRNA and protein levels significantly decreased in livers of Keap1-siRNA-injected mice. In these animals, histological liver damage was less evident than in control mice when challenged with ConA. Likewise, markers of cellular death (FasL and caspases 8, 3 and 1) decreased at 4 and 8 hours post-injection. Nuclear Nrf2 and its target, hemoxygenase 1 (HO1), were elevated in Keap1-siRNA-injected mice compared with control animals, resulting in reduced oxidative stress in the liver. Similarly, mRNA levels of pro-inflammatory cytokines were reduced in livers from Keap1-siRNA-injected mice. At the molecular level, activation of c-jun (NH2) terminal kinase (JNK) was ameliorated, whereas the insulin-like growth factor I receptor (IGFIR) survival pathway was maintained upon ConA injection in Keap1-siRNA-treated mice. In conclusion, our results have revealed a potential therapeutic use of in vivo siRNA technology targeted to Keap1 to combat oxidative stress by modulating Nrf2-mediated antioxidant responses and IGFIR survival signaling during the progression of ALF.

Nitrosative stress and nitrated proteins in trichloroethene-mediated autoimmunity

Exposure to trichloroethene (TCE), a ubiquitous environmental contaminant, has been linked to a variety of autoimmune diseases (ADs) including SLE, scleroderma and hepatitis. Mechanisms involved in the pathogenesis of ADs are largely unknown. Earlier studies from our laboratory in MRL+/+ mice suggested the contribution of oxidative/nitrosative stress in TCE-induced autoimmunity, and N-acetylcysteine (NAC) supplementation provided protection by attenuating oxidative stress. This study was undertaken to further evaluate the contribution of nitrosative stress in TCE-mediated autoimmunity and to identify proteins susceptible to nitrosative stress. Groups of female MRL +/+ mice were given TCE, NAC or TCE + NAC for 6 weeks (TCE, 10 mmol/kg, i.p., every 4^th day; NAC, ∼250 mg/kg/day via drinking water). TCE exposure led to significant increases in serum anti-nuclear and anti-histone antibodies together with significant induction of iNOS and increased formation of nitrotyrosine (NT) in sera and livers. Proteomic analysis identified 14 additional nitrated proteins in the livers of TCE-treated mice. Furthermore, TCE exposure led to decreased GSH levels and increased activation of NF-κB. Remarkably, NAC supplementation not only ameliorated TCE-induced nitrosative stress as evident from decreased iNOS, NT, nitrated proteins, NF-κB p65 activation and increased GSH levels, but also the markers of autoimmunity, as evident from decreased levels of autoantibodies in the sera. These findings provide support to the role of nitrosative stress in TCE-mediated autoimmune response and identify specific nitrated proteins which could have autoimmune potential. Attenuation of TCE-induced autoimmunity in mice by NAC provides an approach for designing therapeutic strategies.

Non-thermal atmospheric pressure plasma preferentially induces apoptosis in p53-mutated cancer cells by activating ROS stress-response pathways

Non-thermal atmospheric pressure plasma (NTAPP) is an ionized gas at room temperature and has potential as a new apoptosis-promoting cancer therapy that acts by generating reactive oxygen species (ROS). However, it is imperative to determine its selectivity and standardize the components and composition of NTAPP. Here, we designed an NTAPP-generating apparatus combined with a He gas feeding system and demonstrated its high selectivity toward p53-mutated cancer cells. We first determined the proper conditions for NTAPP exposure to selectively induce apoptosis in cancer cells. The apoptotic effect of NTAPP was greater for p53-mutated cancer cells; artificial p53 expression in p53-negative HT29 cells decreased the pro-apoptotic effect of NTAPP. We also examined extra- and intracellular ROS levels in NTAPP-treated cells to deduce the mechanism of NTAPP action. While NTAPP-mediated increases in extracellular nitric oxide (NO) did not affect cell viability, intracellular ROS increased under NTAPP exposure and induced apoptotic cell death. This effect was dose-dependently reduced following treatment with ROS scavengers. NTAPP induced apoptosis even in doxorubicin-resistant cancer cell lines, demonstrating the feasibility of NTAPP as a potent cancer therapy. Collectively, these results strongly support the potential of NTAPP as a selective anticancer treatment, especially for p53-mutated cancer cells.

Protein kinase RNA-like endoplasmic reticulum kinase (PERK) signaling pathway plays a major role in reactive oxygen species (ROS)-mediated endoplasmic reticulum stress-induced apoptosis in diabetic cardiomyopathy

Background

Endoplasmic reticulum (ER) stress is considered one of the mechanisms contributing to reactive oxygen species (ROS)- mediated cell apoptosis. In diabetic cardiomyopathy (DCM), cell apoptosis is generally accepted as the etiological factor and closely related to cardiac ROS generation. ER stress is proposed the link between ROS and cell apoptosis; however, the signaling pathways and their roles in participating ER stress- induced apoptosis in DCM are still unclear.

Methods

In this study, we investigated the signaling transductions in ROS- dependent ER stress- induced cardiomocyte apoptosis in animal model of DCM. Moreover, in order to clarify the roles of IRE1 (inositol - requiring enzyme-1), PERK (protein kinase RNA (PKR)- like ER kinase) and ATF6 (activating transcription factor-6) in conducting apoptotic signal in ROS- dependent ER stress- induced cardiomocyte apoptosis, we further investigated apoptosis in high- glucose incubated cardiomyocytes with IRE1, ATF6 and PERK- knocked down respectively.

Results

we demonstrated that the ER stress sensors, referred as PERK, IRE1 and ATF6, were activated in ROS- mediated ER stress- induced cell apoptosis in rat model of DCM which was characterized by cardiac pump and electrical dysfunctions. The deletion of PERK in myocytes exhibited stronger protective effect against apoptosis induced by high- glucose incubation than deletion of ATF6 or IRE in the same myocytes. By subcellular fractionation, rather than ATF6 and IRE1, in primary cardiomyocytes, PERK was found a component of MAMs (mitochondria-associated endoplasmic reticulum membranes) which was the functional and physical contact site between ER and mitochondria.

Conclusions

ROS- stimulated activation of PERK signaling pathway takes the major responsibility rather than IRE1 or ATF6 signaling pathways in ROS- medicated ER stress- induced myocyte apoptosis in DCM.

Adjunctive N-acetyl-L-cysteine in treatment of murine pneumococcal meningitis

Despite antibiotic therapy, acute and long-term complications are still frequent in pneumococcal meningitis. One important trigger of these complications is oxidative stress, and adjunctive antioxidant treatment with N-acetyl-l-cysteine was suggested to be protective in experimental pneumococcal meningitis. However, studies of effects on neurological long-term sequelae are limited. Here, we investigated the impact of adjunctive N-acetyl-l-cysteine on long-term neurological deficits in a mouse model of meningitis. C57BL/6 mice were intracisternally infected with Streptococcus pneumoniae. Eighteen hours after infection, mice were treated with a combination of ceftriaxone and placebo or ceftriaxone and N-acetyl-l-cysteine, respectively. Two weeks after infection, neurologic deficits were assessed using a clinical score, an open field test (explorative activity), a t-maze test (memory function), and auditory brain stem responses (hearing loss). Furthermore, cochlear histomorphological correlates of hearing loss were assessed. Adjunctive N-acetyl-l-cysteine reduced hearing loss after pneumococcal meningitis, but the effect was minor. There was no significant benefit of adjunctive N-acetyl-l-cysteine treatment in regard to other long-term complications of pneumococcal meningitis. Cochlear morphological correlates of meningitis-associated hearing loss were not reduced by adjunctive N-acetyl-l-cysteine. In conclusion, adjunctive therapy with N-acetyl-l-cysteine at a dosage of 300 mg/kg of body weight intraperitoneally for 4 days reduced hearing loss but not other neurologic deficits after pneumococcal meningitis in mice. These results make a clinical therapeutic benefit of N-acetyl-l-cysteine in the treatment of patients with pneumococcal meningitis questionable.

A peptide against soluble guanylyl cyclase α1: a new approach to treating prostate cancer

Among the many identified androgen-regulated genes, sGCα1 (soluble guanylyl cyclase α1) appears to play a pivotal role in mediating the pro-cancer effects of androgens and androgen receptor. The classical role for sGCα1 is to heterodimerize with the sGCβ1 subunit, forming sGC, the enzyme that mediates nitric oxide signaling by catalyzing the synthesis of cyclic guanosine monophosphate. Our published data show that sGCα1 can drive prostate cancer cell proliferation independent of hormone and provide cancer cells a pro-survival function, via a novel mechanism for p53 inhibition, both of which are independent of sGCβ1, NO, and cGMP. All of these properties make sGCα1 an important novel target for prostate cancer therapy. Thus, peptides were designed targeting sGCα1 with the aim of disrupting this protein’s pro-cancer activities. One peptide (A-8R) was determined to be strongly cytotoxic to prostate cancer cells, rapidly inducing apoptosis. Cytotoxicity was observed in both hormone-dependent and, significantly, hormone-refractory prostate cancer cells, opening the possibility that this peptide can be used to treat the usually lethal castration-resistant prostate cancer. In mouse xenograft studies, Peptide A-8R was able to stop tumor growth of not only hormone-dependent cells, but most importantly from hormone-independent cells. In addition, the mechanism of Peptide A cytotoxicity is generation of reactive oxygen species, which recently have been recognized as a major mode of action of important cancer drugs. Thus, this paper provides strong evidence that targeting an important AR-regulated gene is a new paradigm for effective prostate cancer therapy.

Endoplasmic reticulum stress signaling is involved in mitomycin C (MMC)-induced apoptosis in human fibroblasts via PERK pathway

Endoplasmic reticulum (ER) stress-mediated cell apoptosis has been implicated in various cell types, including fibroblasts. Previous studies have shown that mitomycin C (MMC)-induced apoptosis occurs in fibroblasts, but the effects of MMC on ER stress-mediated apoptosis in fibroblasts have not been examined. Here, MMC-induced apoptosis in human primary fibroblasts was investigated by exposing cells to a single dose of MMC for 5 minutes. Significant inhibition of cell proliferation and increased apoptosis were observed using a cell viability assay, Annexin V/propidium iodide double staining, cell cycle analysis, and TUNEL (terminal deoxynucleotidyl transferase dUTP nick-end labeling) staining. Upregulation of proapoptotic factors, including cleaved caspase-3 and poly ADP-ribose polymerase (PARP), was detected by Western blotting. MMC-induced apoptosis was correlated with elevation of 78-kDa glucose-regulated protein (GRP78) and C/EBP homologous protein (CHOP), which are hallmarks of ER stress. Three unfolded protein response (UPR) sensors (inositol-requiring enzyme 1, IRE1; activating transcription factor 6, ATF6; and PKR-like ER kinase, PERK) and their downstream signaling pathways were also activated. Knockdown of CHOP attenuated MMC-induced apoptosis by increasing the ratio of BCL-2/BAX and decreasing BIM expression, suggesting that ER stress is involved in MMC-induced fibroblast apoptosis. Interestingly, knockdown of PERK significantly decreased ER stress-mediated apoptosis by reducing the expression of CHOP, BIM and cleaved caspase-3. Reactive oxygen species (ROS) scavenging also decreased the expression of GRP78, phospho-PERK, CHOP, and BIM. These results demonstrate that MMC-induced apoptosis is triggered by ROS generation and PERK activation.

Oxidative DNA damage is involved in ochratoxin A-induced G2 arrest through ataxia telangiectasia-mutated (ATM) pathways in human gastric epithelium GES-1 cells in vitro

Ochratoxin A (OTA), one of the most abundant mycotoxin food contaminants, is classified as "possibly carcinogenic to humans." Our previous study showed that OTA could induce a G2 arrest in immortalized human gastric epithelium cells (GES-1). To explore the putative roles of oxidative DNA damage and the ataxia telangiectasia-mutated (ATM) pathways on the OTA-induced G2 arrest, the current study systematically evaluated the roles of reactive oxygen species (ROS) production, DNA damage, and ATM-dependent pathway activation on the OTA-induced G2 phase arrest in GES-1 cells. The results showed that OTA exposure elevated intracellular ROS production, which directly induced DNA damage and increased the levels of 8-OHdG and DNA double-strand breaks (DSBs). In addition, it was found that OTA treatment induced the phosphorylation of the ATM protein, as well as its downstream molecules Chk2 and p53, in response to DNA DSBs. Inhibition of ATM by the pharmacological inhibitor caffeine or siRNA effectively prevented the activation of ATM-dependent pathways and rescued the G2 arrest elicited by OTA. Finally, pretreatment with the antioxidant N-acetyl-L-cysteine (NAC) reduced the OTA-induced DNA DSBs, ATM phosphorylation, and G2 arrest. In conclusion, the results of this study suggested that OTA-induced oxidative DNA damage triggered the ATM-dependent pathways, which ultimately elicited a G2 arrest in GES-1 cells.

Vα14iNKT cell deficiency prevents acetaminophen-induced acute liver failure by enhancing hepatic glutathione and altering APAP metabolism

Acetaminophen (APAP) overdose is widely regarded as a major cause of acute liver failure in the United States. Intentional or accidental overdose of APAP in man or rodent elicits direct hepatocellular injury that is accompanied by hepatic depletion of the antioxidant, glutathione (GSH). In recent years, the innate immune response has also been shown to promote the development of APAP hepatotoxicity via indirect liver damage. In the present study, we demonstrate that Jα18(-/-) mice, which are selectively deficient in the innate immune T cell, Vα14iNKT cells, were resistant to APAP hepatotoxicity relative to WT mice as reflected by biochemical and histological liver injury markers. In parallel, improvement in the biochemical and histological parameters of liver injury in Jα18(-/-) mice was associated with a significant increase in hepatic levels of GSH, which detoxified APAP metabolites to attenuate hepatic oxidative stress, liver injury and necrosis. Notably, the protective effect of hepatic GSH during Vα14iNKT cells deficiency was demonstrated by its depletion in Jα18(-/-) mice using dl-buthionine-[S,R]-sulfoximine which exacerbated hepatic oxidative and nitrosative stress as well as liver necrosis and caused mice mortality. Extraordinarily, APAP metabolism in Jα18(-/-) mice was altered in favor of hepatic GSH conjugates and decreased glucuronide conjugates. In summary, we reveal a novel finding establishing a unique association between hepatic innate immunity and GSH levels in altering APAP metabolism to suppress liver injury and necrosis during Vα14iNKT cells deficiency in Jα18(-/-) mice.