Reactive oxygen species-induced activation of Yes-associated protein-1 through the c-Myc pathway is a therapeutic target in hepatocellular carcinoma

BACKGROUND The Hippo signaling pathway regulates organ size by regulating cell proliferation and apoptosis with terminal effectors including Yes-associated protein-1(YAP-1).Dysregulation in Hippo pathway has been proposed as one of the therapeutic targets in hepatocarcinogenesis.The levels of reactive oxygen species(ROS)increase during the progression from early to advanced hepatocellular carcinoma(HCC).AIM To study the activation of YAP-1 by ROS-induced damage in HCC and the involved signaling pathway.METHODS The expression of YAP-1 in HCC cells(Huh-7,HepG2,and SNU-761)was quantified using real-time polymerase chain reaction and immunoblotting.Human HCC cells were treated with H2O2,which is a major component of ROS in living organisms,and with either YAP-1 small interfering RNA(siRNA)or control siRNA.To investigate the role of YAP-1 in HCC cells under oxidative stress,MTS assays were performed.Immunoblotting was performed to evaluate the signaling pathway responsible for the activation of YAP-1.Eighty-eight surgically resected frozen HCC tissue samples and 88 nontumor liver tissue samples were used for gene expression analyses.RESULTS H2O2 treatment increased the mRNA and protein expression of YAP-1 in HCC cells(Huh-7,HepG2,and SNU-761).Suppression of YAP-1 using siRNA transfection resulted in a significant decrease in tumor proliferation during H2O2 treatment both in vitro and in vivo(both P<0.05).The oncogenic action of YAP-1 occurred via the activation of the c-Myc pathway,leading to the upregulation of components of the unfolded protein response(UPR),including 78-kDa glucoseregulated protein and activating transcription factor-6(ATF-6).The YAP-1 mRNA levels in human HCC tissues were upregulated by 2.6-fold compared with those in nontumor tissues(P<0.05)and were positively correlated with the ATF-6 Levels(Pearson’s coefficient=0.299;P<0.05).CONCLUSION This study shows a novel connection between YAP-1 and the UPR through the c-Myc pathway during oxidative stress in HCC.The ROS-induced activation of YAP-1 via the c-Myc pathway,which leads to the activation of the UPR pathway,might be a therapeutic target in HCC.

Organogermanium (Ge-132) Suppresses Activities of Stress Enzymes Responsible for Active Oxygen Species in Monkey Liver Preparation

Assays of stress enzymes related to active oxygen species were performed by using an in vitro preparation from the liver of a monkey (Japanese Macaque). Ge-132, an organic germanium compound, viz. poly-trans-[(2-carboxyethyl) germasesquioxane] [(GeCH2CH2COOH)2O3]n, suppressed the activities of NADH-dependent oxidase and NADPH-dependent oxidase [NAD(P)H-OD] and xanthine oxidase (XOD) as superoxide-forming enzymes, while promoting the activities of superoxide dismutase (SOD) as a superoxide-scavenging enzyme and catalase (CAT) as an enzyme responsible for degradation of hydrogen peroxide (H2O2). The evidence suggests that the levels of active oxygen species such as and H2O2 would be reduced by Ge-132. The possible connection between Ge-132 and activities of stress enzymes is discussed on the basis of these results.

Gallic Acid Isolated from Pomegranate Peel Extract Induces Reactive Oxygen Species Mediated Apoptosis in A549 Cell Line

Antioxidant properties elicited by plant species have a full range of perspective applications in human health care. In recent years, the prevention of cancer and cardiovascular diseases has been associated with the ingestion of fresh fruits, vegetables or teas rich in natural antioxidants [1]. Extracts from the different part of the pomegranate plant such as juice, seed and peel have been reported to exhibit a potent antioxidant activity. But the anticarcinogenic activity of active principle from the pomegranate peel extract was not studied so far. Hence the present study was planned to explore the molecular mechanism of the anticarcinogenic activity pomegranate peel on A549 cell line. In this study, GC-MS analysis was carried out for the methanolic extract of pomegranate peel which revealed gallic acid (GA) as the major antioxidant compound in the extract. Hence GA was purified further through RP-HPLC and evaluated its anticancer potential by studying its effect on mitochondrial respiration, cell-membrane integrity, apoptotic body formation and the DNA fragmentation in cultured A549 cells. We observed increased level of reactive oxygen species in the cells treated with GA at the concentrations of 10 and 20 ug/ml. Further analysis of caspase activation (caspase 8 and 9) revealed activation of caspases 9 in the cells treated with GA at a concentration of 20 ug/ml. Thus the present study revealed that the GA isolated from the pomegranate peel extract (Kabul variety) induced apoptosis in A549 cells through intrinsic pathway.

Tocilizumab Significantly Decreases Reactive Oxygen Species Level in Patients with Rheumatoid Arthritis

To determine the effect of tocilizumab (TCZ) on reactive oxygen species (ROS) in 11 patients with rheumatoid arthritis (RA), reactive oxygen metabolites (d-ROM) were measured using a Free Radical Elective Evaluator. The Disease Activity Score (DAS28) and matrix metalloproteinase-3 (MMP-3) level were also evaluated. d-ROM measured 392 ± 110 Carratelli units [U. CARR] on initiation of TCZ, and significantly decreased to 237 ± 82, 248 ± 88, and 226 ± 91 U.CARR after 3, 6, and 12 months, respectively

Evaluation of Reactive Oxygen Species (ROS) Generated on the Surface of Copper Using Chemiluminesence

The antibacterial activity of copper is well-known from an ancient civilization, however, its biocidal mechanism has not been necessarily elucidated. Notwithstanding up to now, mainly 4 processes have been proposed. Among them, it is cleared that 4 kinds of reactive oxygen species (ROS): hydroxyl radical ·OH, hydrogen per oxide H2O2, superoxide anion ·O-2 and singlet oxygen 1O2, play an important role for contact-killing of bacteria, viruses and fungi. In this paper, generation of ROS on the surfaces of copper plates heated from room temperature to 673 K for 4.2 × 102 s in air, was investigated using the chemiluminescence. ROS have been evaluated by selecting the most suitable scavengers, such as 2-propanol for ·OH, sodium pyruvate for H2O2, nitro blue tetrazolium for ·O-2, and sodium azide NaN3 for 1O2. At the same time the outermost surface of copper, on which thin film of cuprous oxide Cu2O was first formed and then cupric oxide CuO was laminated on Cu2O, was examined by thin-film XRD and TEM analysis to estimate the amounts and kinds of copper oxides. It was found that the most amounts of ROS were obtained for the 573 K-heated Cu plate and they were composed of ·OH, H2O2, and ·O-2..

Effect of Lanthanum (Ⅲ) on Reactive Oxygen Metabolism of Soybean Seedlings under Supplemental UV-B Irradiation

The effect of lanthanum （Ⅲ） on reactive oxygen metabolism of soybean seedlings under elevated ultraviolet-B radiation（UV-B：280~320 nm）at 0.15 and 0.45 W·cm-2 levels respectively was studied through hydroponics in the laboratory.Plasmolemma permeability and contents of malonadialdehyde（MDA）,hydrogen peroxide（H2O2）,and proline gradually increased during the imposition of UV-B radiation and subsequently decreased during recovery from UV-B stress.The dynamic tendency of catalase（CAT）activity was similar to that of the above four indices.The activity of peroxidase（POD）initially increased,then remained at a high level,and finally dropped steeply when soybean seedlings were exposed to a low dosage of UV-B radiation.However,POD activity rose throughout and declined slightly on the eleventh day when soybean seedlings were stressed by a high dosage.With the addition of La （Ⅲ） of 20 mg·L-1,the rising tendency of plasmolemma permeability and contents of MDA,H2O2,and proline were slowed down during the stress period,whereas the declining speed was accelerated during the recovery period.The activities of CAT and POD were higher than those without La （Ⅲ） in all experiments.It suggested that the regulative effect of La （Ⅲ） on antioxidant enzymes such as CAT and POD could strengthen their capacities to scavenge reactive oxygen species（ROS）,decrease contents of MDA and proline,and maintain normal plasmolemma permeability.Further more,the protective potential of La （Ⅲ） was better under low UV-B radiation than under a high one.

Study of Physicochemical Properties and Active Oxygen in Structures ofLayered Mixed La_(4)BaCu_(5-x)MxO_(13+λ)(M=Mn,Co)

Two series of layered mixed oxides La4BaCu5-xMxO13+(M=Mn, Co, x=05) were prepared and characterized by means of XRD, XPS, O2TPD and chemical analysis. The results show that their structures are 5layered ABO3 perovskite, and the XPS and O2TPD investigation confirms that there exists synergistic effect between Cu ion and M when M ion is doped into the lattice of La4BaCu5O13+, and the synergistic effect between Mn and Cu is stronger than that of CuCo.

Effect of Foliar GA_(3) and ABA Applications on Reactive Oxygen Metabolism in Black Currants (Ribes nigrum L.) During Bud Para-dormancy and Secondary Bud Burst

The secondary bud burst can cause around 10%-20%yield losses in black currants,an economically important crop in parts of Europe,Asia and North America.The metabolism of reactive oxygen species(ROS)has been linked to bud dormancy and its early release(secondary bud burst)in several fruit crops.But the relationship between ROS metabolism and the secondary bud burst is still not well understood in black currants.In the present study,two black currant cultivars(Adelinia and Heifeng)with opposing tendency of exhibiting the secondary bud burst were sprayed with abscisic acid(ABA)and gibberellic acid(GA_(3))to either inhibit or induce the secondary bud burst.The results showed that ABA inhibited the secondary bud burst by reducing the contents of ROS(H_(2)O_(2),O_(2)-·)in buds;decreasing the activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT);and increasing the contents of oxidized glutathione(GSSG)and ascorbic acid(AsA).GA_(3) effectively induced the secondary bud burst by increasing ROS contents;increasing the activities of several antioxidant enzymes,such as SOD,POD,CAT,glutathione reductase(GR),ascorbate peroxidase(APX)and the contents of reduced glutathione(GSH);and decreasing the contents of AsA.The experimental results showed that GA_(3) treatment increased the content of ROS,accelerated the metabolism of reactive oxygen species,and promoted the second burst of black currants.However,ROS metabolism was at a low level under ABA treatment,and the buds remained dormant.These results suggested that ROS metabolism might play an important role in the two black currants of the secondary bud burst.

Effects of Different Cadmium Levels on Active Oxygen Metabolism and H_2O_2-Scavenging System in Brassica campestris L.ssp.chinensis

The effects of different Cd (Cadmium) levels on generation of active oxygen speceies(AOS) and H2O2-scavenging system in the leaves of Brassica campestris L. ssp. chinensiswere studied. The results showed that generation rate, and H2O2 content were enhancedand malondialdehyde (MDA) content increased with the increase of Cd concentrations inthe growth medium. The activities of ascorbate peroxidase (APX), dehydroascorbatereductase (DR) and glutathione reductase (GR) were promoted by the addition of Cd.Exposed to Cd also increased the contents of ascorbate (AsA) and glutathione (GSH) in theleaves.

逆境条件下植物活性氧(AOS)的研究进展

对逆境条件下的植物活性氧的产生及其双重作用的研究进展进行了综述。植物在正常生长条件下活性氧(AOS)就存在 ,但在非生物胁迫条件下含量有所变化。植物在适应逆境条件时AOS被认为起关键作用。此时 ,AOS可能起到双重作用 ,高浓度时对植物起到伤害作用 ,低浓度时起到传递信号作用。

Role of oxygen vacancies and Sr sites in SrCo_(0.8)Fe_(0.2)O_3 perovskite on efficient activation of peroxymonosulfate towards the degradation of aqueous organic pollutants

Metal-based perovskite oxides have contributed significantly to the advanced oxidation processes(AOPs)due to their diverse active sites and excellent compositional/structural flexibility.In this study,we specially designed a perovskite oxide with abundant oxygen vacancies,SrCo_(0.8)Fe_(0.2)O_(3)(SCF),and firstly applied it as a catalyst in peroxymonosulfate(PMS) activation towards organic pollutants degradation.The result revealed that the prepared SCF catalyst exhibited excellent performance on organic compounds degradation.Besides,SCF showed much better activity than La_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3)(LSCF) in terms of reaction rate and stability for the degradation of the organic compounds.Based on the analysis of scanning electron microscope,transmission electron microscope,X-ray diffraction,N_(2) adsorption-desorption,X-ray photoelectron spectroscopy and electron paramagnetic resonance,it was confirmed that the perovskite catalysts with high content of Sr doping at A-site could effectively create a defect-rich surface and optimize its physicochemical properties,which was responsible for the excellent heterogeneous catalytic activity of SCF.SCF can generate three highly active species:~1 O_(2),SO_(4)^(-)· and ·OH in PMS activation,revealing the degradation process of organic compounds was a coupled multiple active species in both radical and nonradical pathway.Moreover,it was mainly in a radical pathway in the degradation through PMS activation on SCF and SO_(4)^(-)· radicals produced were the dominant species in SCF/PMS system.This study demonstrated that perovskite-type catalysts could enrich OVs efficiently by doping strategy and regulate the PMS activation towards sulfate radical-based AOPs.

Au^(δ-)-O_(v)-Ti^(3+):Active site of MO_(x)-Au/TiO_(2) catalysts for the aerobic oxidation of 5-hydroxymethylfurfural

Despite wide applications of noble metal-based catalysts in 5-hydroxymethylfurfural(HMF)oxidation,promoting the catalytic performance at low loading amounts still remains a significant challenge.Herein,a series of metal oxide modified MO_(x)-Au/TiO_(2)(M=Fe,Co,Ni)catalysts with low Au loading amount of 0.5 wt%were synthesized.Addition of transition metal oxides promotes electron transfer and generation of the Au^(δ-)-O_(v)-Ti^(3+)interface.A combination study reveals that the dual-active site(Au^(δ-)-O_(v)-Ti^(3+))governs the catalytic performance of the ratedetermining step,namely hydroxyl group oxidation.Au^(δ-) site facilitates chemisorption and activation of O_(2) molecules.At the same time,O_(v)-Ti^(3+) site acts as the role of“killing two birds with one stone”:enhancing adsorption of both reactants,accelerating the activation and dissociation of H_(2)O,and facilitating activation of the adsorbed O_(2).Besides,superoxide radicals instead of base is the active oxygen species during the rate-determining step.On this basis,a FDCA yield of 71.2% was achieved under base-free conditions,complying with the“green chemistry”principle.This work provides a new strategy for the transition metal oxides modification of Au-based catalysts,which would be constructive for the rational design of other heterogeneous catalysts.

Theory of pleiotropic action of biologically active compounds and medicines—Basic principles and practical application

This article represents the main positions of the theory of pleiotropic action of biologically active compounds (BACs) and medicines, which has been designed by the author based on her own experimental researches. The term “pleiotropy” means the ability of the BACs and medicines to implement more than one mechanism of action resulting in the specific biological (pharmacological) effect. The interaction of these mechanisms forms a distinct pattern of biological response (pleiotropic pattern), which reflects the change in his character with the increased dose (concentration)-dependent efficacy of BACs and medicines. The article consists of description of different pleiotropic patterns established in experiments on the model of reactive oxygen species (ROS) generation by macrophages dependent on activity of specialized enzyme called Nox2-NAD(P)H oxidase (Nox2, EC 1.6.3.1). Moreover, it consists of explanation of pharmacodynamic nature of pleiotropic patterns by means of application Chou-Talalay median effect equalization and combination index (CI) theory. The novel theory explains unsolved until now universal aspects of activity BACs and medicines, such as slope angles of “dose-effect” dependences in the conditions relevant in vivo, and it is of fundamental interest. However, it has applications in experimental pharmacology, as it allows defining the choice of the individual compounds and combinations, modulating the trust effect selectively and efficiently. This knowledge opens up new approaches to medicines discovery and evaluation, their rational dosing and combining.

Formation of active oxygen species on single-atom Pt catalyst and promoted catalytic oxidation of toluene

Catalytic oxidation of toluene over noble metal catalysts is a representative reaction for elimination of volatile organic compounds(VOCs).However,to fully understand the activation of molecular oxygen and the role of active oxygen species generated in this reaction is still a challenging target.Herein,MgO nanosheets and single-atom Pt loaded MgO(Pt SA/MgO)nanosheets were synthesized and used as catalysts in toluene oxidation.The activation process of molecular oxygen and oxidation performance on the two catalysts were contrastively investigated.The Pt SA/MgO exhibited significantly enhanced catalytic activity compared to MgO.The oxygen vacancies can be easily generated on the Pt SA/MgO surface,which facilitate the activation of molecular oxygen and the formation of active oxygen species.Based on the experimental data and theoretical calculations,an active oxygen species promoted oxidation mechanism for toluene was proposed.In the presence of H2O,the molecular oxygen is more favorable to be dissociated to generate•OH on the oxygen vacancies of the Pt SA/MgO surface,which is the dominant active oxygen species.We anticipate that this work may shed light on further investigation of t10.1007/s12274-020-2765-1he oxidation mechanism of toluene and other VOCs over noble metal catalysts.

Active oxygen species and oxidation mechanism over Ce-doped LaMn_(0.8)Ni_(0.2)O_(3)/hierarchical ZSM-5 in pentanal oxidation

Hierarchical ZSM-5(HZ)molecular sieves based on fly ash were synthesized using a method combining water heat treatment with step-by-step calcination.The coupling catalysts between La_(1-x)Ce_(x)Mn_(0.8)-Ni_(0.2)O_(3)(x≤0.5)perovskites and HZ were prepared through the impregnation method,which were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM),N_(2)adsorption,X-ray photoelectron spectroscopy(XPS),NH3-temperature programmed desoprtion(NH3-TPD),H_(2)-temperature programmed reduction(H_(2)-TPR)and O_(2)-TPD techniques and investigated regarding pentanal oxidation at 120-390℃to explore the effects of Ce doping on the catalytic activity and the active oxygen species of the coupling catalysts,meanwhile,the reaction mechanism and pathway of pentanal oxidation were also studied.The results reveal that Ce substitution at La sites can change the electronic interactions between all the elements and promote the electronic transfer among La,Ce,Ni,Mn and HZ,influencing directly the physicochemical characteristics of the catalysts.Moreover,the amount and transfer ability of surface adsorbed oxygen(O_(2)-and O-)regarded as the reactive oxygen species and the low temperature reducibility are the main influence factors in pentanal oxidation.Additionally,La_(0.8)Ce_(0.2)Mn_(0.8)Ni_(0.2)O_(3)/HZ exhibits the best catalytic activity and deep oxidation capacity as well as a better water resistance due to its larger amount of surface adsorbed oxygen species and higher low temperature reducibility.What’s more,appropriate Ce substitution can significantly enhance the amount of O_(2)-ions,which can distinctly enhance the catalytic activity of the catalyst,and moderate acid strength and appropriate acid amount can also facilitate the improvement of the pentanal oxidation activity.It is found that there is a synergic catalytic effect between surface acidity and redox ability of the catalyst.According to the in situ DRIFTS and GC/MS analyses,pentanal can be oxidized gradually to CO_(2)and H_(2)O by the surface oxygen species with the form of adsorption in air following the Langmuir-Hinshelwood(L-H)reaction mechanism.Two reaction pathways for the pentanal oxidation process are proposed,and the conversion of the formates to carbonates may be one of the main rate-determining steps.

Enhanced catalysis of ultrasmall Au-MoS_2 clusters against reactive oxygen species for radiation protection

Ionizing radiation produces excessive reactive oxygen species （ROS） which impose detrimental effects on biological systems. Thus, it is important to explore clinically safe and efficacious radioprotection agents to scavenge ROS and reduce the risks of radiotherapy. Recently, emerging catalytic nanomaterials such as sulfide nanomaterials have shown capability of clearing ROS in vivo by unique electron transfers between atoms, but their catalytic activities are yet suboptimal. As such, there is an unmet need to improve cat- alytic properties for stronger antioxidant activities and radiation protection. Herein, we prepared ultra- small Au-MoS2 clusters （~2.Snm） and they showed enhanced catalytic properties via gold intercalation facilitating increased active sites and synergistic effects. Electrocatalysis results revealed that the catalytic activity of Au-MoS2 towards 1-1202 was superior to ultrasmall MoS2 without Au. As a result, we found that improving the electrocatalytic property of Au-MoS2 can effectively enhance corre- sponding antioxidant activities and radioprotection effects in vivo. In addition, Au-MoS2 also showed sig- nificant radioprotection in vitro and dramatically reduced the excess of radiation-induced adverse ROS. It also rescued radiation-induced DNA damages and protected the bone marrow hematopoietic system from ionizing radiation.

Sub-cytotoxic concentrations of ionic silver promote the proliferation of human keratinocytes by inducing the production of reactive oxygen species

Silver-containing preparations are widely used in the management of skin wounds, but the effects of silver ions on skin wound healing remain poorly understood. This study investigated the effects of silver ions （Ag^＋） on the proliferation of human skin keratinocytes （HaCaT） and the production of intracellular reactive oxygen species （ROS）. After treating HaCaT cells with Ag^＋ and/or the active oxygen scavenger N-acetyl cysteine （NAC）, cell proliferation and intracellular ROS generation were assessed using CCK-8 reagent and DCFH-DA fluorescent probe, respectively. In addition, 5-bromo-2-deoxyUridine （BrdU） incorporation assays, cell cycle flow cytometry, and proliferating cell nuclear antigen （PCNA） immunocytochemistry were conducted to further evaluate the effects of sub-cytotoxic Ag^＋ concentrations on HaCaT cells. The proliferation of HaCaT cells was promoted in the presence of 10^-6 and 10^-5s mol/L Ag^＋at 24, 48, and 72 h. Intracellular ROS generation also significantly increased for 5 60 min after exposure to Ag^＋ The number of BrdU-positive cells and the presence of PCNA in HaCaT cells increased 48 h after the addition of 10^-6 and 10^-5 mol/L Ag^＋, with 10^-5 mol/L Ag^＋ markedly increasing the cell proliferation index. These effects of sub-cytotoxic Ag^＋ concentrations were repressed by 5 mmol/L NAC. Our results suggest that sub-cytotoxic Ag^＋ concentrations promote the proliferation of human keratinocytes and might be associated with a moderate increase in intracellular ROS levels. This study provides important experimental evidence for developing novel silver-based wound agents or dressings with few or no cytotoxicity.

Teasaponin induces reactive oxygen species-mediated mitochondrial dysfunction in Candida albicans

Candida albicans is the most prevalent commensal fungus and readily causes invasive fungal infection in immunocompromised individuals. Teasaponin(TS), a natural product generally regarded as safe, has been reported to inhibit filamentation of C. albicans. This study found that TS could exert moderate fungicidal activity against C. albicans, and the mode of action was further explored. The minimum fungicidal concentration(MFC) was determined by the broth microdilution method. The colony counting method was used to determine the time-killing curve of TS against C. albicans in every 2 h. The effect of TS on the content of intracellular reactive oxygen species(ROS) in C. albicans was analyzed by 2′,7′-dichlorofluorescin diacetate(DCFH-DA) staining, and the mitochondrial membrane potential(mtΔψ) was determined by rhodamine123(RH123) staining. An ATP assay kit was utilized to determine the intracellular ATP levels after TS treatment. Results showed that TS-induced ROS accumulation and mitochondrial dysfunction contributed to the death of C. albicans cells. Further research demonstrated that VC could reinforce the fungicidal ability of TS. On the contrary, VE could antagonize the function of TS against C. albicans, which might guide the clinical application of TS. The results preliminarily elucidated the potential mechanisms of TS against C. albicans and might provide a potential option for the treatment of clinical Candida.

Thrombin promotes human lung fibroblasts to proliferate via NADPH oxidase/reactive oxygen species/extracellular regulated kinase signaling pathway

Background Thrombin is a multifunctional serine protease that plays a crucial role in hemostasis following tissue injury.In addition to its procoagulation effect, thrombin is also a potent mesenchymal cell mitogen, therefore it plays important roles in the local proliferation of mesenchymal cells in the tissue repair process. Reactive oxygen species （ROS） can induce some human cells to proliferate at lower rates while at higher concentrations they promote cells to undergo apoptosis or necrosis. Accumulative evidence suggests that thrombin can induce some cells to produce ROS. Based on these observations, we provide a hypothesis that thrombin can stimulate human lung fibroblasts to produce ROS, which play an important role in human lung fibroblast proliferation.Methods ROS were detected in fibroblasts at 30 minutes and 60 minutes following thrombin （20 U/ml） exposure using flow cytometry. The ratio of reduced glutathione/oxidized glutathione （GSH/GSSG） was assayed in lung fibroblasts using a commercial kit following treatment with thrombin at different concentrations. NADPH oxidase and the extracellular regulated kinase1/2 （ERK1/2） signaling pathway were detected by Western blotting after thrombin stimulation to lung fibroblasts.Results Thrombin, at 20 U/ml, stimulated human lung fibroblasts （HLF） to generate ROS in a time dependent manner.The ratio of GSH/GSSG in fibroblasts treated with thrombin showed a significant decrease. NADPH oxidase was activated and the ERK1/2 signal pathway was involved in the proliferation process of fibroblasts treated with thrombin.Conclusion The activation of NADPH oxidase by thrombin leads to the production of ROS, which promotes fibroblasts proliferation via activation of the ERK1/2 signaling pathway.