Bacterial Contamination in the Different Parts of Household Washing Machine: New Insights from Chengdu, Western China.

The moist and warm environment in the household washing machine provides ideal living conditions for the growth and survival of various microorganisms. However, the biodiversity of bacterial community in the different parts of washing machine from Chinese households has not been clarified. In this study, we assessed the bacterial communities in sealing strip, detergent drawer, inner drum, water filter and greywater of ten domestic washing machines quantitatively and qualitatively in Chengdu, southwestern China. The microbial cultivation results indicated that the washing machines from Chengdu had a severe microbial contamination reflected by large counts on bacteria, fungi and coliform. Furthermore, the sequencing data showed that the different parts displayed distinctive bacterial compositions. At the level of genus, the anaerobic bacteria of Caproiciproducens and Acidipropionibacterium were predominant in sealing strip. Barnesiella, Shinella and Sellimonas were detected as the characteristic bacteria in detergent drawer. The pathogens of Luteibacter and Corynebacterium at the genus level were the dominant bacteria in inner drum and water filter, respectively. The genera of Azospira, Roseococcus, Elstera and Aquicella, which belonged to the pathogenic phylum of Proteobacteria, were identified as bioindicators for the greywater. Gene function analysis on the sequencing data illustrated that the bacteria from washing machines were potentially associated with bacterial infectious diseases and antimicrobial resistance. This study shows the bacterial diversity in the different parts of washing machines, providing new clues for bacterial contamination in washing machines from Chinese households.

Spatial-temporal distribution and source analysis of atmospheric particulate-bound cadmium from 1998 to 2021 in China.

Cadmium (Cd) is one of the most serious atmospheric heavy metal pollutants in China. PM2.5, PM10, and total suspended particle (TSP) are all important media for population Cd exposure. However, no studies so far have systematically explored the spatial and temporal distribution of atmospheric Cd bound to all these media in China, and the specific industrial sectors that contribute to the airborne Cd level are still unclear at present. In this study, we constructed the spatial and temporal distribution of PM (PM2.5, PM10, and TSP) binding Cd concentrations in China. Quantitative source apportionment of atmospheric Cd was carried out by analyzing the association of 23 industrial or energy-consuming sectors with Cd concentrations. Our results showed PM2.5, PM10, and TSP binding Cd concentrations decreased by 5.8%, 5.9%, and 6.1% per year at the national level, respectively. High PM-Cd concentrations were concentrated and distributed mainly in central and northwestern China. In addition, the medians of atmospheric PM2.5, PM10, and TSP binding Cd concentrations at the national level were 0.0026 µg/m3, 0.0036 µg/m3, and 0.0042 µg/m3, respectively. The main sources of PM-Cd include nonferrous metal smelting (Zn, Pb, Al) (47%), glass production (13%), pesticide production (12%), cement production (10%), and coal consumption (9%). This study analyzes comprehensively the atmospheric PM-bound Cd pollution, identifies the major industrial sectors that affect atmospheric Cd concentrations at the macroscale for the first time, and provides a basis for further reduction in the atmospheric Cd pollution.

[Mechanism of Triclosan in the Treatment of Nonalcoholic Fatty Liver Disease Based on Network Pharmacology].

Objective To explore the potential targets of triclosan in the treatment of nonalcoholic fatty liver disease(NAFLD) and to provide new clues for the future research on the application of triclosan. Methods The targets of triclosan and NAFLD were obtained via network pharmacology.The protein-protein interaction network was constructed with the common targets shared by triclosan and NAFLD.The affinity of triclosan to targets was verified through molecular docking.Gene ontology(GO) annotation and Kyoto Encyclopedia of Genes and Genomes(KEGG) pathway enrichment were carried out to analyze the key targets and the potential mechanism of action.NAFLD model was established by feeding male C57BL/6J mice with high-fat diet for 12 weeks.The mice were randomly assigned into a model group and a triclosan group [400 mg/(kg·d),gavage once a day for 8 weeks].The hematoxylin-eosin(HE) staining was used for observation of the pathological changes and oil red O staining for observation of fat deposition in mouse liver.Western blotting was employed to detect the protein level of peroxisome proliferator-activated receptor alpha(PPARα) in the liver tissue. Results Triclosan and NAFLD had 34 common targets,19 of which may be the potential targets for the treatment,including albumin(ALB),PPARα,mitogen-activated protein kinase 8(MAPK8),and fatty acid synthase.Molecular docking predicted that ALB,PPARα,and MAPK8 had good binding ability to triclosan.KEGG pathway enrichment showcased that the targets were mainly enriched in peroxisome proliferator-activated receptor signaling pathway,in which ALB and MAPK8 were not involved.Triclosan alleviated the balloon-like change and lipid droplet vacuole,decreased the lipid droplet area,and up-regulated the expression level of PPARα in mouse liver tissue. Conclusion PPARα is a key target of triclosan in the treatment of NAFLD,which may be involved in fatty acid oxidation through the peroxisome proliferator activated receptor signaling pathway.

Fat mass and obesity-associated protein regulates lipogenesis via m6 A modification in fatty acid synthase mRNA.

As the first identified N6 -methyladenosine (m6 A) demethylase, fat mass and obesity-associated (FTO) protein is associated with fatty acid synthase (FASN) and lipid accumulation. However, little is known about the regulatory role of FTO in the expression of FASN and de novo lipogenesis through m6 A modification. In this study, we used FTO small interfering RNA to explore the effects of FTO knockdown on hepatic lipogenesis and its underlying epigenetic mechanism in HepG2 cells. We found that knockdown of FTO increased m6 A levels in total RNA and enhanced the expression of YTH domain family member 2 which serves as the m6 A-binding protein. The de novo lipogenic enzymes and intracellular lipid content were significantly decreased under FTO knockdown. Mechanistically, knockdown of FTO dramatically enhanced m6 A levels in FASN messenger RNA (mRNA), leading to the reduced expression of FASN mRNA through m6 A-mediated mRNA decay. The protein expressions of FASN along with acetyl CoA carboxylase and ATP-citrate lyase were further decreased, which inhibited de novo lipogenesis, thereby resulting in the deficiency of lipid accumulation in HepG2 cells and the induction of cellular apoptosis. The results reveal that FTO regulates hepatic lipogenesis via FTO-dependent m6 A demethylation in FASN mRNA and indicate the critical role of FTO-mediated lipid metabolism in the survival of HepG2 cells. This study provides novel insights into a unique RNA epigenetic mechanism by which FTO mediates hepatic lipid accumulation through m6 A modification and indicates that FTO could be a potential target for obesity-related diseases and cancer.

[Comparative Analysis of Direct Drinking Water and the Relevant Sanitation Standards in China].

Along with the economic and technological development and growing demand for high-quality drinking water, direct drinking water has gained general popularity in China. However, no authoritative policy has been issued, giving a clear definition of direct drinking water and existing standards and regulations concerning direct drinking water are not definitive in nature. Existing water quality parameters are not well supported and sometimes even contradict each other. We elaborated, in this paper, the history of direct drinking water in China and systematically reviewed the existing regulations and standards related to direct drinking water. We also compared and analyzed the important microbiology, toxicology, sensory perception and general chemistry parameters in the standards. This paper is the first ever attempt at an in-depth analysis of the chaotic state of the direct drinking water industry. We have also highlighted the problems in the current standards and regulations for direct drinking water. Our study provides a basis for market regulation and the supervision and management of direct drinking water. In addition, the paper provides helpful information for laying down a definition of direct drinking water, calling for and approving of project proposals concerning the establishment of national standards for direct drinking water, and actually formulating the standards. We have made a number of suggestions: A. defining direct drinking water clearly and formulating the national standards for direct drinking water as soon as possible; B. conducting research on water quality benchmarks to provide scientific support for the formulation of the national standards for direct drinking water; C. giving more attention to the formulation of standards concerning microbiology parameters and their limits and giving consideration to the inclusion of parameters concerning viruses.

Evaluation of DNA and chromosomal damage in two human HaCaT and L02 cells treated with varying triclosan concentrations.

Triclosan has been used in a large number of consumer products and concerns have been raised over regarding potential genotoxicity. However, the genotoxicity of triclosan has not been assessed in normal human cells. The aim of this study was to examine the potential genotoxicity using the comet assay and micronucleus (MN) test to detect DNA damage and chromosomal breakage attributed to triclosan in human keratinocyte HaCaT and hepatic L02 cells. The concentrations of triclosan selected for the comet assay and MN test were based upon preliminary results from cytotoxicity testing in order to reduce cytotoxic effects. The mutagenicity of triclosan was assessed in Salmonella reverse mutation assay (Ames test). Results of comet assay showed that 5, 7.5 or 10 µM triclosan did not markedly affect olive tail moment (OTM) in HaCaT and L02 cells. In addition, no significant alterations in MN frequency were found in cells treated with triclosan. Further, treatment with 10 µg/plate triclosan produced inhibitory effects in bacterium using Ames test, while 1 and 0.1 µg/plate triclosan did not markedly affect the number of colonies or mutant frequencies of Salmonella strains. Taken together, triclosan did not cause DNA and chromosomal damage in HaCaT and L02 cells and did not induce gene mutations in Salmonella strains under our experimental conditions.

Arsenite-induced endoplasmic reticulum-dependent apoptosis through disturbance of calcium homeostasis in HBE cell line.

Calcium (Ca2+ ) is a ubiquitous cell signal responsible for multiple fundamental cellular functions, including apoptosis. Whether the homeostasis of Ca2+ is involved in arsenite-induced apoptosis remains unclear. In this study, we observed that arsenite significantly elevated the intracellular Ca2+ concentration in a dose- and time-dependent manner. By using the Ca2+ -ATPase inhibitor, thapsigargin, and the inositol 1,4,5- trisphosphate receptors (IP3Rs) inhibitor, heparin, we further confirmed that the disturbance of endoplasmic reticulum (ER) Ca2+ homeostasis caused Ca2+ overload in the cells. Moreover, loss of ER Ca2+ homeostasis also led to ER stress, mitochondrial dysfunction, and NF-κB activation. Importantly, pretreatment of cells with heparin remarkably attenuated the elevated cell apoptosis induced by arsenite, but inhibition of ER Ca2+ uptake with thapsigargin exacerbated arsenite-induced cell damage significantly. Together, we demonstrated for the first time that arsenite disturbed the Ca2+ homeostasis in ER, which subsequently led to ER stress, mitochondrial dysfunction, and NF-κB nuclear translocation, and thus consequently triggering cell apoptosis. Our findings indicate regulation of disrupted Ca2+ homeostasis in ER may be a potential strategy for prevention of arsenite toxicity. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 197-216, 2017.

Protection of Nrf2 against arsenite-induced oxidative damage is regulated by the cyclic guanosine monophosphate-protein kinase G signaling pathway.

Arsenite has been shown to induce a variety of oxidative damage in mammalian cells. However, the mechanisms underlying cellular responses to its adverse effects remain unknown. We previously showed that the level of Nrf2, a nuclear transcription factor significantly increased in arsenite-treated human bronchial epithelial (HBE) cells suggesting that Nrf2 is involved in responding to arsenite-induced oxidative damage. To explore how Nrf2 can impact arsenite-induced oxidative damage, in this study, we examined Nrf2 activation and its regulation upon cellular arsenite exposure as well as its effects on arsenite-induced oxidative damage in HBE cells. We found that Nrf2 mRNA and protein levels were significantly increased by arsenite in a dose- and time-dependent manner. Furthermore, we showed that over-expression of Nrf2 significantly reduced the level of arsenite-induced oxidative damage in HBE cells including DNA damage, chromosomal breakage, lipid peroxidation and depletion of antioxidants. This indicates a protective role of Nrf2 against arsenite toxicity. This was further supported by the fact that activation of Nrf2 by its agonists, tertiary butylhydroquinone (t-BHQ) and sulforaphane (SFN) resulted in the same protective effects against arsenite toxicity. Moreover, we demonstrated that arsenite-induced activation of Nrf2 was mediated by the cyclic guanosine monophosphate (cGMP)-protein kinase G (PKG) signaling pathway. This is the first evidence showing that Nrf2 protects against arsenite-induced oxidative damage through the cGMP-PKG pathway. Our study suggests that activation of Nrf2 through the cGMP-PKG signaling pathway in HBE cells may be developed as a new strategy for prevention of arsenite toxicity. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 2004-2020, 2017.

[Inhibition of WIP1 in A549 cells enhances the sensitivity of cells to arsenic treatment].

OBJECTIVE: To explore if inhibiting the expression of wild-type p53-induced phosphatase 1( WIP1) could enhance the sensitivity of A549 cells to arsenic. METHODS: To inhibit expression of WIP1, WIP1 siRNA was transferred into A549 cells by using Lipofectamine 2000. Then the protein expression levels of P53 phosphorylation proteins and their downstream effectors were detected by western-blot analysis. Cell apoptosis were assessed by Annexin V-FITC stain assay. The sensitivity of transferred cells to arsenic was detected by using MTT assay. RESULTS: The mRNA and protein expression level of WIP1 were all decreased by 70 % in A549 cells transferred with WIP1 siRNA. Western-blot analysis indicated that P53 phosphorylation process was much accelerated in WIP1-inhibited cells after arsenic treatment. For example, compared to control cells, an significant decrease in P53 ser15 expression and an increase in P53 ser46 expression was found in WIP1-inhibited cells when treated with As_2O_3( 5-40 µmol/L). In addition, compared to control group, the expression of P21 decreased whereas PUMA increased in WIP1-inhibited cells when treated with As_2O_3( 10-40 µmol/L). Cell viability of WIP1-inhibited cells after As_2O_3 treatment( 5-40 µmol/L) was significantly higher than that of the control group, which may be due to a high apoptosis rate in WIP1-inhibited cells. CONCLUSION: WIP1 could be used as a new target in arsenic-base anticancer therapies.

[Improving the expression of TP53INP1 in A549 cells enhances the sensitivity of cells to arsenic treatment].

OBJECTIVE: To explore if improving the expression of TP53INP1 could enhance the sensitivity of A549 cells to arsenic. METHODS: The eukaryotic express vector containing TP53INP1 gene was transferred into A549 cells by using lentivirus vector. Cell apoptosis and cell viability after arsenic treatment were assessed by flow cytometry and MTT assay, respectively. RESULTS: The protein expression level of TP53INP1 was increased in A549 cells transferred with eukaryotic express vector containing TP53INP1 gene, which led to an increase in apoptosis and a decrease in cell viability. Compared with A549 cells, significant increase in apoptosis was found in A549-TP53INP1 cells when treated with As_2O_3( 5- 40 µmol/L). In addiation, the IC50 of As_2O_3 in A549-TP53INP1(( 44. 64 ± 6. 84) µmol/L) cells was significantly lower than that of the A549 group(( 54. 25 ± 6. 13) µmol/L)( P < 0. 05). CONCLUSION: Enhancement of TP53INP1 can significantly improve apoptosis response and enhance sensitivity of A549 cells to arsenic. It is suggested that TP53INP1 could be used as a new target in arsenic-based cancer treatment.

[Effect of Cell Autophagy on the Apoptosis of Hepatocellular Carcinoma Cells Induced by Arsenic Trioxide].

OBJECTIVES: To determine the effect of autophagy on the apoptosis of hepatocellular carcinoma cells induced by arsenic trioxide (ATO). METHODS: Hepatocellular carcinoma HepG2 cells were exposed to ATO. The cell viability was detected by MTT after adjustments for autophagy agonist (Rap) and autophagy inhibitor (3-MA). The autophagosome was observed under electronic microscope. The autophagy related proteins (LC3 and Beclin1) were detected by immunofluorescence. The cell apoptosis was measured by flow cytometry. RESULTS: With 5-20 µmol/Lof ATO, HepG2 cells exposed to 3-MA had significantly lower viability (P <0.05) and higher early apoptosis (P <0.05) than those without exposure to 3-MA. Exposure to 3-MA was also associated with lower expressions of LC3 and Beclin1, with HepG2 cells showing typical apoptotic characteristics. By contrast, with 5-20 µmol/Lof ATO, the cells exposed to Rap showed significantly higher viability (P <0.05) and lower early apoptosis (P<0.05) than those without exposure to Rap. A large number of autophagosome appeared in the cells exposed to Rap. Exposure to Rap was associated with increased expressions of LC3 and Beclin1, but with no statistical significance (P >0.05). CONCLUSION: Targeted autophagy inhibition can significantly increase the sensitivity of HepG2 to ATO. The underlining mechanism is associated with enhanced apoptosis of hepatocellular carcinoma cells.

[miR-155/BACH1 Signaling Pathway in Human Lung Adenocarcinoma Cell Death Induced by Arsenic Trioxide].

OBJECTIVE: To explore the changes of micro RNA 155 (miR-155),BTB and CNC homologous protein 1 (BACH1),quinone oxidoreductase 1 (NQO1) and heme-oxygenase-1 (HO-1) in the process of arsenic trioxide-induced cell death,and to clarify the relationship between miR-155 and BACH1,providing experimental basis for the sensitivity of arsenic trioxide (ATO) treatment. METHODS: Human lung adenocarcinoma cell line A549 cells were treated with different concentrations of ATO. MTT assay and total antioxidant capacity detection kit were used to determine cell viability and total antioxidant capacity,respectively. BACH1,NQO1 and HO-1 protein expression were probed by Western blot and real-time fluorescence quantitative (qRT-PCR) was utilized to test the miR-155 level. A549 cells were transfected with miR-155 mimic and its negative control,then the expression level of miR-155 was detected by qRT-PCR,and these cells were treated with 20 µmol/L for 24 h followed by MTT and Western blot detection. RESULTS: 10 µmol/L ATO significantly reduced the cell viability in A549 cells. 10 µmol/L and 20 µmol/L ATO treatment activated BACH1 expression and inhibited miR-155,NQO1 and HO-1 expression,leading to decreased total antioxidant capacity. Importantly,the cell death induced by 20 µmol/L ATO was significantly decreased in miR-155 mimic transfection cells in comparison with non-transfected cells and miR-155 mimic negative control transfected cells. Moreover,high expression of miR-155 reduced BACH1 activation and increased NQO1 and HO-1 expression in cells treated with 20 µmol/L ATO ( P<0.05). CONCLUSION: Restraining total antioxidant capacity contributes to ATO induced cell death,the underlying mechanisms may be that ATO can activate BACH1 expression through inhibition of the miR-155 level,leading to subsequent inhibition of NQO1 and HO-1 expression. Taken together,these data suggest that miR-155 and BACH1 could be used as sensitivity targets for ATO treatment in lung cancer.

Base excision repair of oxidative DNA damage coupled with removal of a CAG repeat hairpin attenuates trinucleotide repeat expansion.

Trinucleotide repeat (TNR) expansion is responsible for numerous human neurodegenerative diseases. However, the underlying mechanisms remain unclear. Recent studies have shown that DNA base excision repair (BER) can mediate TNR expansion and deletion by removing base lesions in different locations of a TNR tract, indicating that BER can promote or prevent TNR expansion in a damage location-dependent manner. In this study, we provide the first evidence that the repair of a DNA base lesion located in the loop region of a CAG repeat hairpin can remove the hairpin, attenuating repeat expansion. We found that an 8-oxoguanine located in the loop region of CAG hairpins of varying sizes was removed by OGG1 leaving an abasic site that was subsequently 5'-incised by AP endonuclease 1, introducing a single-strand breakage in the hairpin loop. This converted the hairpin into a double-flap intermediate with a 5'- and 3'-flap that was cleaved by flap endonuclease 1 and a 3'-5' endonuclease Mus81/Eme1, resulting in complete or partial removal of the CAG hairpin. This further resulted in prevention and attenuation of repeat expansion. Our results demonstrate that TNR expansion can be prevented via BER in hairpin loops that is coupled with the removal of TNR hairpins.

Nuclear translocation of nuclear factor kappa B is regulated by G protein signaling pathway in arsenite-induced apoptosis in HBE cell line.

Arsenite is a certainly apoptosis inducer in various cell types. However, the detailed mechanism underlying how arsenite trigger apoptosis remains elusive. In this study, using human bronchial epithelial cell as a culture system, we demonstrated that arsenite-induced nuclear translocation of nuclear factor kappa B (NF-κB) resulted in the release of cytochrome c, the modulation of Fas and FasL, caspase activation, and ultimately leading to cell apoptosis. Importantly, we showed for the first time that the NF-κB-mediated apoptosis induced by arsenite was regulated by G protein-adenylate cyclase (AC)-cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) pathway. Inhibition of this classical G protein signaling pathway by a typical PKA inhibitor, H-89, caused the inactivation of NF-κB, the depletion of caspase-3, 8 and 9 activities, and thus reducing the level of cell apoptosis. Taken together, our results indicate that arsenite is able to trigger cell apoptosis in human bronchial epithelial cells through the nuclear translocation of NF-κB, which can be modulated by G protein signaling pathway. These findings further suggest that inhibition of G protein-mediated pathway by specific inhibitors may be a potential strategy for the prevention of arsenite toxicity. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1819-1833, 2016.

[Role of nuclear factor E2 related factor 2 signaling pathway in malignant transformation induced by sodium arsenite].

OBJECTIVE: To construct the malignant transformation model of human bronchial epithelial (HBE) cell line by exposing to low level of sodium arsenite and determine if the nuclear factor E2 related factor 2 (Nrf2) signaling pathway is involved in this process. METHODS: HBE cells were continuously exposed to 2.5 micromol/L sodium arsenite and malignant transformation occurred as evidenced by the MTT assay, colony formation assay and cell migration assay. Western blot was used to evaluate the expression of Nrf2, quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (10-1) during sodium arsenite-induced transformation of HBE cells. RESULTS: MTT assay demonstrated that the proliferation of HBE cells was out of control with increasing passages of sodium arsenite exposure. In As-HBE-T25 and As-HBE-T50 cells, the cell invasion ability was 2.04 and 4.17 times than that in normal HBE cells and colony formation rate was 1.33% depedent manner (P < 0.5). Also, the expresion of QO1 and HO-1, downstream of Nrf2 target proteins, were also decreased with the expression of Nrf2. CONCLUSION: The transformation of HBE cells induced by chronic exposure to sodium arsenite is mediated by decreased Nrf2 level and its downstream NQO1 and HO-1 protein, which subsequently promote the malignant proliferation.

[Study on the resveratrol and arsenic trioxide combination induced apoptosis and its mechanism on lung adenocarcinoma cells].

OBJECTIVE: To explore the synergistically effects and mechanisms of resveratrol (RES) enhanced the oxidative stress and apoptotic cell death induced by As2O3 (arsenic trioxide). METHODS: According to the result of MTT assay, human lung adenocarcinoma A549 cells were divided into four treatment groups as follow: control group, single RES or As2O3 treated group and the group treated with RES and As2O3. Then the differences of cell viability, colony formation, level of ROS, GSH content, mitochondrial membrane potential and apoptosis rate were compared with single or combined treatment. In addition, pre-treatment with L-buthionine sulfoximine (L-BSO), the inhibitory of GSH synthesis, was used to identify the role of GSH in synergistically apoptosis induced by RES and As2O3. RESULTS: The detected results demonstrated that RES could effectively inhibited the growth of A549 cells when its concentration above 20 µmol/L, and inhibition effects was concentration dependent manner. The rate of colony formation, GSH content, mitochondrial membrane potential and apoptosis rate in combination group were significantly lower than that of single RES or As2O3 treatment group (P < 0.05), whereas, RES markedly increased the level of ROS, the expression of cytochrome c and caspase 3 induced by As2O3. When pre-treatment with BSO before RES and As2O3 combination incubation, beside the apoptosis rate was increased from 30.0% to 77.7%, the GSH content was sharply depleted while ROS massively accumulated in intracellular. CONCLUSION: RES could significantly intensified the effects of As2O3 in inhibiting the proliferation, depleting GSH content, ROS accumulation, mitochondrial membrane potential decline and cytochrome c releasing, thus leading to cells apoptosis via Cas-3 activation in a mitochondria-dependent pathway.

[The Experiment Study and Mechanism of Aspirin Enhances Cellular Sensitivity of Hepatocellular Carcinoma Cell Line to Arsenic Trioxide].

OBJECTIVE: To explore whether aspirin could sensitize arsenic trioxide on human hepatocelluar carcinoma cell line and understanding the combination mechanisms underlying co-treatment. METHODS: Cell viability was detected by MTT assay, cell apoptosis rate and reactive oxygen species (ROS) level were measured by flow cytometry, and Western blot assay was used to estimated the protein expression of heme oxygenase-1 (HO-1) in total protein and NF-E2-related factor 2 (Nrf2) in nuclear protein. RESULTS: 10 µmol/L arsenic trioxide can decreased the cell viability, while cell apoptosis rate, ROS level, HO-1 and Nrf2 protein expression was increased (P < 0.05). When compared with arsenic trioxide alone, co-treatment of arsenic trioxide with aspirin in different concentration (0, 0.1, 1.0, 2.5, 5.0 mmol/L) exhibited dual effects in intracellular ROS level, HO-1 and Nrf2 expression. Specifically, with the increasing of aspirin concentrations, the level of ROS induced by arsenic trioxide showed a rising trend after the first reduction, whereas, HO-1 and Nrf2 protein expression were decreased at first and then increased. CONCLUSION: Low concentration, less than 2.5 mmol/L, of aspirin may reduce the ROS accumulation through activating of Nrf2-HO-1 pathway, therefore decreasing the apoptotic cell death induced by arsenic trioxide. On the contrary, 5 mmol/L aspirin could increase the sensitivity of HepG2 to arsenic trioxide through enhancing the arsenic trioxide-induced apoptosis by ROS accumulation resulting in inhibiting the Nrf2-HO-1 pathway.

[The Protective Effect of Inhibition of PARP-1 on Inflammation Induced by PM2.5 in Human Bronchial Epithelial Cell Line.]

OBJECTIVES: To explore whether the inhibition of poly ADP-ribose polymerase-1(PARP-1) could attenuated inflammation induced by fine particulate matter (PM2.5) in human bronchial epithelial cell line. METHODS: Cell viability was detected by Trypan Blue assay after incubated with PM2.5 for 24 h.PM2.5 doses no more than 600 µg/mL were utilized in the following experiments.In order to observe how PARP-1 would effect the expression of nuclear factor-κB p65 and inducible nitric oxide synthase (iNOS),cells were respectively treated with 600 µg/mL PM2.5,10 µmol/L 4-amino-1, 8-naphthalimide (4-AN),600 µg/mL PM2.5+10 µmol/L 4-AN or DMSO.Western blot assay was used to estimate the protein expression of PARP-1,p65 in nuclear and iNOS in cytoplasm.Nitric acid enzyme reduction assay was used to determine the production of nitric oxide (NO). RESULTS: As the PM2.5 concentration increased,the cell viability decreased,while the expression of PARP-1,p65,iNOS and NO increased significantly (P<0.05).After pretreatment of 4-AN for 24 h,the expression of PARP-1,p65,iNOS and NO almost decreased to the normal level(P>0.05). CONCLUSIONS: Inflammation triggered by PM2.5 could be attenuated by the inhibition of PAPR-1,which involved the block of transcriptional activity of NF-κB for inflammatory mediator.

[4-amino-1,8-naphthalimide on the Sensitive effect of arsenic trioxide in hepatocellular carcinoma cells].

OBJECTIVE: To study the effect and mechanism of 4-amino-1, 8-naphthalimide (4-AN) on the sensitive effect of arsenic trioxide (ATO) in hepatocellular carcinoma cells. METHODS: Hepatocellular carcinoma HepG2 cells were divided into two groups according to whether they were treated with 4-AN or not. Cell viability was evaluated by MTT assay, population doubling experiment and colony formation assay; genic mechanism was explored by 8-OH-dG assay, single cell gel electrophoresis (comet assay) and microriucleus test. RESULTS: At 2-10 micromol/L concentration of ATO, the cell viability and colony formation efficiency of the combinatio group (4-AN+ATO) were significantly lower than that of the ATO group (P<0.05); moreover, the tail-length (L-Tail) and olive tail moment (OTM) in comet assay were notablely higher than that of the ATO group (P<0.05). At 2-20 micromol/L concentration of ATO, the population doubling time and 8-OH-dG in combination group were significantly higher than that of ATO group (P<0.05). Results from DNA damage repair assay showed that the efficiency of DNA damage repair in combination group was remarkably lower than that of ATO group (P<0.05). At 5-20 micromol/L concentration of ATO, the frequency of micronucleated cells in combination group was significantly higher than that of ATO group (P<0.05). CONCLUSION: 4-AN can significantly increase the sensitivity of ATO in treatment with hepatocellular carcinoma cells and prevent DNA damage repair may be a primary mechanism for this effect.

[Research on the sodium arsenite and arsenic trioxide induced proliferation and apoptosis effects on human hepatocyte].

OBJECTIVE: To explore the proliferation and apoptosis effects induced by sodium arsenite and arsenic trioxide on human hepatocyte L02 and provide evidence for the paradox effects of arsenic. METHODS: Human hepatocyte L02 was treated by a series of concentration of sodium arsenite or arsenic trioxide, respectively. Cytotoxicity were tested by MTT assay and colony formation assay, cellular apoptosis and cell cycle were detected by flow cytometry, chromosomal breakage were measured by micronucleus test and reactive oxygen species level and GSH contents were detected with commercial kits. RESULTS: With the increase of sodium arsenite or arsenic trioxide concentrations, cellular viability, colony formation rate and GSH contents decreased; inhibition of colony formation, cellular apoptotic rate, reactive oxygen species level and frequency of micronuclei increased, and dosed cells were both arrested in G2/M phase of cell cycle. CONCLUSION: Both sodium arsenite and arsenic trioxide could induce oxidative stress in human hepatocyte L02 and result in chromosomal damage, apoptosis, cell cycle arrest and cellular proliferation inhibition, suggesting that oxidative stress induction might be the common molecular mechanism of malignant transformation induced by sodium arsenite and therapeutic effects exhibited by arsenic trioxide.