1,4-Benzoquinone (PBQ) Induced Toxicity in Lung Epithelial Cells Is Mediated by the Disruption of the Microtubule Network and Activation of Caspase-3

Petunidin attenuates vinclozolin instigated testicular toxicity in albino rats via regulating TLR4/MyD88/TRAF6 and Nrf-2/Keap-1 pathway: A pharmacodynamic and molecular simulation approach

Vinclozolin (VZN) is a widely used fungicide which exerts deleterious impacts on various organs including testis. Petunidin (PDN) is a polyphenolic compound that demonstrates a broad range of pharmacological activities. Thirty-two rats were divided into 4 groups including the control, VZN (100 mg/kg), VZN (100 mg/kg) + PDN (4 mg/kg) and PDN (4 mg/kg) treated group. The activities of antioxidant enzymes were assessed by using previously documented protocols. The gene expressions were determined by using qRT-PCR. The levels of hepatic function and apoptotic markers were evaluated by using standard ELISA technique. The histological analysis was carried out as per the standard protocol of histology. It was revealed that VZN disrupted the Nrf-2/Keap-1 pathway. Moreover, the activities of catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), heme-oxygenase-1 (HO-1) and glutathione reductase (GSR) were reduced whereas levels of reactive oxygen species (ROS) & malondialdehyde (MDA) were promoted following the VZN intoxication. Furthermore, VZN intoxication reduced total sperm count, viability, motility as well as luteinizing hormone (LH), follicle stimulating hormone (FSH), and plasma testosterone. Besides, administration of VZN decreased the expressions of 3β-Hydroxysteroid dehydrogenase (3β-HSD), steroidogenic acute regulatory protein (StAR) and 17β-Hydroxysteroid dehydrogenase (17β-HSD). Moreover, VZN exposure escalated the expressions of Bcl-2-associated X protein (Bax) and cysteine-aspartic acid protease-3 (Caspase-3) while reducing the expressions of B-cell lymphoma-2 (Bcl-2). Additionally, VZN administration increased the gene expression of toll-like receptor 4 (TLR4), tumor necrosis factor receptor-associated factor 6 (TRAF-6) and myeloid differentiation primary response 88 (MyD88). The levels of interleukin-6 (IL-6), nuclear factor kappa-B (NF-κB), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and the activity of cyclooxygenase-2 (COX-2) were promoted following the VZN administration. Furthermore, VZN intoxication disrupted the normal histology of testicular tissues. However, VZN + PDN treatment ameliorated testicular damage via regulating aforementioned dysregulations owing to its anti-inflammatory, antioxidative as well as anti-apoptotic potentials. Lastly, molecular docking (MD) was performed to assess the effectiveness of PDN as a curative compound by analyzing its binding affinity with the targeted proteins (Keap1, TLR4 and StAR). Our in-silico evaluations confirmed that PDN possesses the potential to interact with binding pockets of these proteins, emphasizing its capability as a curative compound to mitigate VZN-prompted reproductive damage.

Strong synergistic and antagonistic effects of quinones and metal ions in oxidative potential (OP) determination by ascorbic acid (AA) assays

A key challenge in oxidative potential (OP) assays is to accurately assess the cumulative impact of redox-active aerosol species rather than only their individual effects. This study investigates the OP of single and combined mixtures of 1,2-naphthoquinone (1,2-NQ), 1,4-naphthoquinone (1,4-NQ), 9,10-phenanthrenequinone (9,10-PQ), 1,4-benzoquinone (1,4-BQ), Cu, Fe, Mn, and Zn in standard ascorbic acid (OPAA) and the synthetic respiratory tract lining fluid (OPRTLF) assays. In both OPAA and OPRTLF, binary mixtures showed additive and synergistic effects in the presence of 1,2-NQ. The mixture of Cu and Zn showed substantial synergisms in both assays, while the mixtures in the absence of 1,2-NQ primarily induced antagonistic effects. For the first time, we propose linear equations to improve the prediction of OP values by considering the impacts of synergistic and antagonistic effects. Under this approach, we observed that the potential effects caused by binary mixtures in ambient particulate matter (PM) samples could account for up to 68 % of the PM-OP values in Fez, Morocco (OPmAA: 0.34 nmol min-1 µg-1 and OPmRTLF: 0.18 nmol min-1 µg-1). The present study improves the understanding of effects of chemical interaction of potentially toxic substances that are important in the understanding of PM-induced oxidative stress in the human body.

Blocking exosomal secretion aggravated 1,4-benzoquinone-induced cytotoxicity

Benzene exposure inhibits the hematopoietic system and leads to the occurrence of various types of leukemia. However, the mechanism underlying the hematotoxicity of benzene is still largely unclear. Emerging evidence has shown that exosomes are involved in toxic mechanisms of benzene. To understand the effect of 1,4-benzoquinone (PBQ; an active metabolite of benzene in bone marrow) on the exosomal release characteristics and role of exosomal secretion in PBQ-induced cytotoxicity. Exosomes were isolated from PBQ-treated HL-60 cells, purified by ultracentrifugation, and verified by transmission electron microscopy, nanoparticle tracking analysis and the presence of specific biomarkers. Our results showed that PBQ increased exosomal secretion in a dose-dependent manner, reaching a peak in 3 h at 10 μM PBQ treatment and then slowly decreasing in HL-60 cells. The exosomes contained miRNAs, which have been reported to be associated with benzene exposure or benzene poisoning. In particular, mir-34a-3p and mir-34A-5p were enriched in exosomes derived from PBQ-treated cells. In addition, the inhibition of exosomal release by GW4869 (an inhibitor of exosomal release) exacerbated PBQ-induced cytotoxicity, including increased intracellular reactive oxygen species levels, decreased mitochondrial membrane potential, and increased the apoptosis rate. Our findings illustrated that exosomes secretion plays an important role in antagonizing PBQ-induced cytotoxicity and maintaining cell homeostasis.

Scoulerine promotes cytotoxicity and attenuates stemness in ovarian cancer by targeting PI3K/AKT/mTOR axis

In women, ovarian cancer is a common gynecological cancer associated with poor prognosis, reoccurrence and chemoresistance. Scoulerine, a benzylisoquinoline alkaloid, has been reported effective against several carcinomas. Thus, we investigated the impact of scoulerine on ovarian cancer cells (OVCAR3). Cell viability was assessed by MTT assay, migration was determined by Boyden Chamber assay, while the invasion was monitored by Boyden Chamber assay using the matrigel. The stemness properties of OVCAR3 cells were observed by tumorsphere assay. Epithelial to mesenchymal transition (EMT) and stemness-related protein markers were monitored by real-time PCR analysis and immunoblotting. Scoulerine inhibits the viability of OVCAR3 cells with the IC 50 observed at 10 µmol L-1 after 48 h treatment. Scoulerine inhibited the colony-forming ability, migration and invasiveness of OVCAR3 cells in a dose-dependent fashion. Scoulerine treatment also drastically reduced the spheroid-forming ability of OVCAR3 cells. The mesenchymal and stemness--related markers like N-cadherin, vimentin, CD-44, Oct-4, Sox-2 and Aldh1A1 were downregulated, whereas the epithelial markers like E-cadherin and CD-24 were upregulated in scoulerine-treated cells. The upstream PI3K/Akt/mTOR-axis was downregulated in scoulerine-treated cells. We concluded that scoulerine successfully perturbs the cancerous properties of OVCAR3 cells by targeting the PI3K/Akt/mTOR axis. In vivo studies revealed a substantial decrease in tumor mass and volume after scoulerine treatment. Furthermore, scoulerine treatment was found to decrease oxidative stress factors in ovarian cancer mice model. Scoulerine is a potential anticancer agent against ovarian cancer and can be considered as a lead molecule for this malignancy, provided further investigations are performed.

Thermodynamics of benzoquinone-induced conformational changes in nucleic acids and human serum albumin

Biological macromolecules such as proteins, nucleic acids, carbohydrates and lipids, play a crucial role in biochemical and molecular processes. Thus, the study of the structure-function relationship of biomolecules in presence of ligands is an important aspect of structural biology. The current communication describes the chemico-biological interaction between benzene metabolite para-benzoquinone (BQ) with B-form of nucleic acids (B-DNA) and human serum albumin (HSA). The binding ability of HSA towards bromocresol green (BCG) was significantly suppressed when exposed to increasing concentrations of BQ in the presence of various physiological buffers. Further, the native fluorescence of HSA was drastically reduced and the secondary structures of HSA were significantly compromised with increasing concentrations of BQ. In vitro and in silico studies also revealed that BQ binds to domains I and II of HSA and thus altering the conformation of HSA which may potentially affect plasma osmotic pressure, as well as the binding and transport of numerous endogenous and exogenous molecules. Similarly, BQ interacts directly to the GC region of B-DNA particularly in the minor groove which was also assessed by computational docking studies. Isothermal titration calorimetry data suggest higher binding affinity of BQ towards DNA than HSA. Various spectroscopic observations also suggest that BQ binds to DNA preferably in the minor grooves. Thus, the results revealed that BQ may play a key role in inducing mutagenicity, either by formation of adducts on GC regions or by accelerating oxidative damage to biomacromolecules through chemico-biological interactions.

Determination of hydroquinone and benzoquinone in pharmaceutical formulations: critical considerations on quantitative analysis of easily oxidized compounds

Hydroquinone is a skin-lightening agent used as an active ingredient in topical dermatological formulations prescribed for treating cutaneous diseases caused by hyperpigmentation. Despite being widely used, some toxicological aspects have been associated with these products, mainly due to overdosage and long-term use combined with the easy oxidation of hydroquinone. In this work, an investigative study has been done to gather enough data for selecting a quantitative analytical method for quality control purposes that considers the ease of oxidation not only within the product but also during the experimental procedures. After studying the influence of pH, reversibility, sampling, and standard solution preparation on the redox reaction between hydroquinone and benzoquinone by using spectroscopic, electrophoretic, and electroanalytical measurements, a reliable, fast, and selective chronoamperometric method was achieved. The optimized method was used for the analysis of samples, previously diluted in Britton-Robinson (BR) buffer (pH 5.5) and methanol (1 : 9, v/v), by applying a potential fixed at 0.4 V. A glassy-carbon working electrode, lab-made Ag/AgCl_(sat) and platinum wire as a reference electrode and auxiliary electrodes, respectively, and BR buffer (pH 5.5) as supporting electrolyte were the additional experimental conditions used. Analytical performance parameters were verified to confirm the applicability of the new method (LOD 4.22 μmol L^-1 and LOQ 14.1 μmol L^-1; recovery mean value of 100% with 0.22% RSD). A gel topical formulation containing 4% (w/w) hydroquinone was analyzed through the developed method for determination of dosage and oxidation traces, and a content of 3.53 ± 0.095% (w/w) was found with no indications of degradation.

Hydrothermal Synthesis of Siderite and Application as Catalyst in the Electro-Fenton Oxidation of p-Benzoquinone

A weak aspect of the electro-Fenton (EF) oxidation of contaminants is the dependence of the Fenton reaction on acidic pH values. Therefore, the rationale of this work was to develop a novel catalyst capable of promoting the EF oxidation process at near-neutral and basic pH values. In this framework, rhombohedral FeCO3 was synthesized hydrothermally and used as a catalyst in the EF oxidation of p-benzoquinone (BQ). The catalyst was characterized using various surface and spectroscopic methods. Moreover, the effects of applied current (100-500 mA), time (1-9 h), catalyst dosage (0.25-1.00 g L-1), and initial concentration of BQ (0.50-1.00 mM) on the total organic carbon removal efficiency were determined. The results indicated that a 400 mA current was sufficient for a 95% total organic carbon removal and that the increase in catalyst dosage had a positive effect on the mineralization of BQ. It was determined that at pH 3, FeCO3 behaved like a homogeneous catalyst by releasing Fe3+ ions; whereas, at the pH range of 5-7, it shifted to a homogeneous/heterogeneous catalyst. At pH 9, it worked solely as a heterogeneous catalyst due to the decrease of Fe ions passing into the solution. Finally, the spent catalyst did not undergo structural deformations after the EF treatment at higher pH values and could be regenerated and used several times.

A review on the degradation of acetaminophen by advanced oxidation process: pathway, by-products, biotoxicity, and density functional theory calculation

Water scarcity and the accumulation of recalcitrance compounds into the environment are the main reasons behind the attraction of researchers to use advanced oxidation processes (AOPs). Many AOP systems have been used to treat acetaminophen (ACT) from an aqueous medium, which leads to generating different kinetics, mechanisms, and by-products. In this work, state-of-the-art studies on ACT by-products and their biotoxicity, as well as proposed degradation pathways, have been collected, organized, and summarized. In addition, the Fukui function was used for predicting the most reactive sites in the ACT molecule. The most frequently detected by-products in this review were hydroquinone, 1,4-benzoquinone, 4-aminophenol, acetamide, oxalic acid, formic acid, acetic acid, 1,2,4-trihydroxy benzene, and maleic acid. Both the experimental and prediction tests revealed that N-(3,4-dihydroxy phenyl) acetamide was mutagenic. Meanwhile, N-(2,4-dihydroxy phenyl) acetamide and malonic acid were only found to be mutagenic in the prediction test. The findings of the LC50 (96 h) test revealed that benzaldehyde is the most toxic ACT by-products and hydroquinone, N-(3,4-dihydroxyphenyl)formamide, 4-methylbenzene-1,2-diol, benzoquinone, 4-aminophenol, benzoic acid, 1,2,4-trihydroxybenzene, 4-nitrophenol, and 4-aminobenzene-1,2-diol considered harmful. The release of them into the environment without treatment may threaten the ecosystem. The degradation pathway based on the computational method was matched with the majority of ACT proposed pathways and with the most frequent ACT by-products. This study may contribute to enhance the degradation of ACT by AOP systems.

Blocking exosomal secretion aggravates 1,4-Benzoquinone-induced mitochondrial fission activated by the AMPK/MFF/Drp1 pathway in HL-60 cells

There is in vivo and in vitro evidence that exposure to benzene or its metabolites could affect the mitochondrial function. However, the underlying molecular mechanism of mitochondrial damage remains to be elucidated. In this study, exposure of human promyelocytic leukemia cells (HL-60) to 1,4-benzoquinone (1,4-BQ; an active metabolite of benzene) increased the intracellular reactive oxygen species levels, decreased the mitochondrial membrane potential, adenosine triphosphate production and mitochondrial DNA (mtDNA) copy number, up-regulated the expression of mitochondrial fission proteins Drp1 and Fis1, and down-regulated the expression of mitochondrial fusion proteins Mfn2 and Opa1. Further study showed that 1,4-BQ mediated mitochondrial fission through activation of the AMP-activated protein kinase/mitochondrial fission factor/dynamin-related protein 1 pathway. Additionally, we also examined the role of exosomal secretion in mitochondrial damage under 1,4-BQ treatment. Results showed that 1,4-BQ increased the total protein level and mtDNA content in exosomes. Upon pre-treatment with the mitochondria-targeted antioxidant SS-31, there was attenuation of the mitochondrial damage induced by 1,4-BQ, accompanied by a change in the exosome release characteristics, while inhibition of exosomal secretion using GW4869 aggravated the 1,4-BQ-mediated mitochondrial fission. We concluded that exosomal secretion may serve as a self-protective mechanism of cells against 1,4-BQ-induced mitochondria damage and mitochondrial dynamics interference.

The lncRNA-AK046375 Upregulates Metallothionein-2 by Sequestering miR-491-5p to Relieve the Brain Oxidative Stress Burden after Traumatic Brain Injury

We previously discovered that traumatic brain injury (TBI) induces significant perturbations in long noncoding RNA (lncRNA) levels in the mouse cerebral cortex, and lncRNA-AK046375 is one of the most significantly changed lncRNAs after TBI. lncRNA-AK046375 overexpression and knockdown models were successfully constructed both in vitro and in vivo. In cultured primary cortical neurons and astrocytes, lncRNA-AK046375 sequestered miR-491-5p, thereby enhancing the expression of metallothionein-2 (MT2), which ameliorated oxidative-induced cell injury. In addition, upregulated lncRNA-AK046375 promoted the recovery of motor, learning, and memory functions after TBI in C57BL/6 mice, and the underlying mechanism may be related to ameliorated apoptosis, inhibited oxidative stress, reduced brain edema, and relieved loss of tight junction proteins at the blood-brain barrier in the mouse brain. Therefore, we conclude that lncRNA-AK046375 enhances MT2 expression by sequestering miR-491-5p, ultimately strengthening antioxidant activity, which ameliorates neurological deficits post-TBI.

Volatilome and Essential Oil of Ulomoides dermestoides: A Broad-Spectrum Medical Insect

Ulomoides dermestoides are used as a broad-spectrum medical insect in the alternative treatment of various diseases. Preliminary volatilome studies carried out to date have shown, as the main components, methyl-1,4-benzoquinone, ethyl-1,4-benzoquinone, 1-tridecene, 1-pentadecene, and limonene. This work focused on the production of metabolites and their metabolic variations in U. dermestoides under stress conditions to provide additional valuable information to help better understand the broad-spectrum medical uses. To this end, VOCs were characterized by HS-SPME with PEG and CAR/PDMS fibers, and the first reported insect essential oils were obtained. In HS-SMPE, we found 17 terpenes, six quinones, five alkenes, and four aromatic compounds; in the essential oils, 53 terpenes, 54 carboxylic acids and derivatives, three alkynes, 12 alkenes (1-Pentadecene, EOT1: 77.6% and EOT2: 57.9%), 28 alkanes, nine alkyl disulfides, three aromatic compounds, 19 alcohols, three quinones, and 12 aldehydes were identified. Between both study approaches, a total of 171 secondary metabolites were identified with no previous report for U. dermestoides. A considerable number of the identified metabolites showed previous studies of the activity of pharmacological interest. Therefore, considering the wide variety of activities reported for these metabolites, this work allows a broader vision of the therapeutic potential of U. dermestoides in traditional medicine.

Natural flavonoid morin showed anti-bacterial activity against Vibrio cholera after binding with cell division protein FtsA near ATP binding site

BACKGROUND

Increasing antibiotic-resistance in bacterial strains has boosted the need to find new targets for drug delivery. FtsA, a major bacterial divisome protein can be a potent novel drug-target.

METHODS AND RESULTS

This study finds, morin (3,5,7,2',4'-pentahydroxyflavone), a bio-available flavonoid, had anti-bacterial activities against Vibrio cholerae, IC₅₀ (50 μM) and MIC (150 μM). Morin (2 mM) kills ~20% of human lung fibroblast (WI38) and human intestinal epithelial (HIEC-6) cells in 24 h in-vitro. Fluorescence studies showed morin binds to VcFtsA (FtsA of V. cholerae) with a K_d of 4.68 ± 0.4 μM, inhibiting the protein's polymerization by 72 ± 7% at 25 μM concentration. Morin also affected VcFtsA's ATPase activity, recording ~80% reduction at 20 μM concentration. The in-silico binding study indicated binding sites of morin and ATP on VcFtsA had overlapping amino acids. Mant-ATP, a fluorescent ATP-derivative, showed increased fluorescence on binding to VcFtsA in absence of morin, but in its presence, Mant-ATP fluorescence decreased. VcFtsA-S40A mutant protein did not bind to morin.

CONCLUSIONS

VcFtsA-morin interaction inhibits the polymerization of the protein by affecting its ATPase activity. The destabilized VcFtsA assembly in-turn affected the cell division in V. cholerae, yielding an elongated morphology.

GENERAL SIGNIFICANCE

Collectively, these findings explore the anti-bacterial effect of morin on V. cholerae cells targeting VcFtsA, encouraging it to become a potent anti-bacterial agent. Low cytotoxicity of morin against human cells (host) is therapeutically advantageous. This study will also help in synthesizing novel derivatives that can target VcFtsA more efficiently.

Siomycin A induces reactive oxygen species-mediated cytotoxicity in ovarian cancer cells

Ovarian cancer is one of the leading causes of cancer-related death among women worldwide and accounts for 4% of all cancer cases in female patients. To date, ovarian cancer has the poorest prognosis among all types of gynecological cancer; thus, it is necessary to identify prospective therapeutic options. Previous studies have demonstrated the involvement of reactive oxygen species (ROS) in the cytotoxicity of various anticancer drugs against several types of carcinoma, including ovarian cancer. The present study aimed to investigate the anticancer effects of Siomycin A, a thiopeptide antibiotic, on the ovarian cancer cell lines PA1 and OVCAR3. To determine the viability of these cells following exposure to Siomycin A, the MTT assay was used, and apoptosis was determined by ELISA. In addition, mitochondrial membrane potential was determined by JC1 staining, and cellular ROS levels were assessed by dichlorodihydrofluorescein diacetate staining in the presence and absence of antioxidant NAC. The subsequent levels of antioxidant enzymes and glutathione were also determined following Siomycin A treatment in the two cell lines. A combination study with Siomycin A and cisplatin indicated enhanced efficiency of the drugs on ovarian cancer cell viability. The results of the present study also demonstrated that Siomycin A induced ROS production, inhibited the major antioxidant enzymes, including catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase and intracellular GSH in PA1 and OVCAR3 cells, and inhibited the cell viability with an IC₅₀ of ~5.0 and 2.5 µM after 72 h respectively compared with the untreated controls. Additionally, the Siomycin A-induced ROS production further targeted apoptotic cell death by impairing the mitochondrial membrane potential and modulating the levels of pro- and antiapoptotic proteins compared with those in the corresponding control groups. The administration of the antioxidant N-acetylcysteine significantly abrogated the cytotoxic effects of Siomycin A. In conclusion, the results of the present study demonstrated the role of ROS in Siomycin A-mediated cytotoxicity in ovarian cancer cells.

Addressing the challenges of E-cigarette safety profiling by assessment of pulmonary toxicological response in bronchial and alveolar mucosa models

Limited toxicity data on electronic cigarette (ECIG) impede evidence-based policy recommendations. We compared two popular mixed fruit flavored ECIG-liquids with and without nicotine aerosolized at 40 W (E-smoke) with respect to particle number concentrations, chemical composition, and response on physiologically relevant human bronchial and alveolar lung mucosa models cultured at air–liquid interface. E-smoke was characterized by significantly increased particle number concentrations with increased wattage (25, 40, and 55 W) and nicotine presence. The chemical composition of E-smoke differed across the two tested flavors in terms of cytotoxic compounds including p-benzoquinone, nicotyrine, and flavoring agents (for example vanillin, ethyl vanillin). Significant differences in the expression of markers for pro-inflammation, oxidative stress, tissue injury/repair, alarm anti-protease, anti-microbial defense, epithelial barrier function, and epigenetic modification were observed between the flavors, nicotine content, and/ or lung models (bronchial or alveolar). Our findings indicate that ECIG toxicity is influenced by combination of multiple factors including flavor, nicotine content, vaping regime, and the region of respiratory tree (bronchial or alveolar). Toxic chemicals and flavoring agents detected in high concentrations in the E-smoke of each flavor warrant independent evaluation for their specific role in imparting toxicity. Therefore, multi-disciplinary approaches are warranted for comprehensive safety profiling of ECIG.

Endosulfan induces cardiotoxicity through apoptosis via unbalance of pro-survival and mitochondrial-mediated apoptotic pathways

Although the associations between endosulfan and adverse cardiovascular health have been reported, the toxic effects and underlying mechanism of endosulfan on the heart are not well understood. In this study, we examined the cardiotoxicity induced by endosulfan using Wistar rats and human cardiomyocytes (AC16) cells. Wistar rats were divided into control group (received corn oil alone) and three concentrations of endosulfan groups (1, 5 and 10 mg/kg·bw) by gavage. The AC16 cells were treated with three various concentrations (0, 1.25, 5, and 20 μg/mL) of endosulfan. The results showed that endosulfan induced cytotoxicity through damaging myocardial structure, decreasing the viability of cardiomyocytes, and elevating the serum levels of cardiac troponin I, heart fatty acid binding protein, aspartate aminotransferase, and reactive oxygen species (p < 0.05). Moreover, measurement of mitochondrial function showed that endosulfan could significantly decrease adenosine triphosphate levels and cytochrome c oxidase IV expression in AC16 cells (p < 0.05). In addition, endosulfan obviously inhibited Bcl-2 expression, activated the expressions of cytochrome c/Caspase-9/Caspase-3 signaling pathway, and induced the apoptosis of AC16 cells (p < 0.05). Furthermore, endosulfan significantly increased the expression of Bim, and inhibited the expressions of PI3K/Akt/FoxO3a signaling pathways in cardiomyocytes (p < 0.05). These results suggest that endosulfan may induce cardiotoxicity by inducing myocardial apoptosis resulting from activation of mitochondria-mediated apoptosis pathway and inhibition of pro-survival signaling pathways, which might be helpful in elucidating the mechanism of cardiac dysfunction induced by endosulfan.

Evaluation of apoptosis and hypoxia-related factors in gingival tissues of smoker and non-smoker periodontitis patients

OBJECTIVE

Smoking causes pathological changes in all tissues, including gingiva and alveolar bone. The aim of present study was to evaluate apoptotic tissue alterations and tissue destruction in smoker and non-smoker periodontitis patients and healthy individuals.

METHODS

Gingival biopsy samples from 15 systemically and orally healthy individuals (Group 1), 15 systemically healthy periodontitis patients (Group 2), 15 systemically and orally healthy smokers (Group 3), and 15 systemically healthy smoker periodontitis patients (Group 4) were enrolled in the present study. Clinical periodontal measurements as plaque index (PI), gingival index (GI), and clinical attachment levels (CAL) were recorded, and gingival biopsies were obtained. Biopsy samples were fixed in formalin solution and embedded in paraffin. Fibroblast and inflammatory cell counts were determined via histomorphometrically. Hypoxia-inducible factor alpha (HIF-1α), vascular endothelial growth factor(VEGF), tissue inhibitor of matrix metalloproteinase-1(TIMP-1), matrix metalloproteinases-8(MMP-8) expressions, Bax, Bcl-2, and caspase-3 expressions were evaluated via immunohistochemistry.

RESULTS

Demographic data of the study groups were similar. Smoking levels of the smokers were also similar. The highest fibroblast cell counts were observed in healthy controls and the counts were similar in other groups. The highest inflammatory cell counts were found in smoker periodontitis group, and the lowest counts were found in healthy control groups. The differences were statistically significant. HIF-1α and Bax expressions were elevated and Bcl-2 decreased in smoker periodontitis patients compared with healthy individuals. However, there were no differences in VEGF, MMP-8, and TIMP-1 expressions.

CONCLUSION

Within limits of present study, it can be suggested that both smoking and periodontitis caused similar decrease in fibroblast counts while causing a dramatic increase in inflammatory cell counts. Increased apoptosis and hypoxia also accompanied to the increased inflammation.

PINK1/Parkin-mediated mitophagy was activated against 1,4-Benzoquinone-induced apoptosis in HL-60 cells

Hematotoxicity of benzene is derived mainly from its active metabolite, 1,4-Benzoquinone (1,4-BQ), which induces cell apoptosis and mitochondrial damage. Damaged mitochondria are degraded through a specialized autophagy pathway, called mitophagy, which is driven by PINK1/Parkin signaling. However, whether mitophagy is involved in 1,4-BQ-induced toxicity remains unclear. This study was designed to investigate whether PINK1/Parkin-mediated mitophagy is activated in 1,4-BQ-treated HL-60 cells, and the roles mitophagy plays in 1,4-BQ-induced apoptosis. Our results demonstrated that 1,4-BQ induced autophagy in HL-60 cells, characterized by increased LC3-II/LC3-I ratio and Beclin1 expression, as well as decreased expression of p62. We confirmed the presence of mitophagosomes using electron microscopy, and found that 1,4-BQ-induced autophagy was blocked by pretreatment with the mitophagy inhibitor Cyclosporine A (CsA). In addition, we found that 1,4-BQ induced mitochondrial stress through decreased mitochondrial membrane potential (MMP) and increasedproduction of reactive oxygen species (ROS). We also confirmed that 1,4-BQ-induced mitophagy was mediated by the PINK1/Parkin pathway, illustrated by increased expression of PINK1 and Parkin mRNA and protein. Finally, we examined 1,4-BQ-induced apoptosis with or without CsA, which demonstrated that apoptosis increased after mitophagy inhibition, suggesting that mitophagy has a protective effect in this context. In conclusion, this study demonstrates that the activated PINK1/Parkin-mediated mitophagy exerts a significantly protective effect against 1,4-BQ-induced apoptosis in HL-60 cells.

Correlation between degradation pathway and toxicity of acetaminophen and its by-products by using the electro-Fenton process in aqueous media

The evolution of the degradation by-products of an acetaminophen (ACE) solution was monitored by HPLC-UV/MS and IC in parallel with its ecotoxicity (Vibrio fischeri 81.9%, Microtox^® screening tests) during electro-Fenton (EF) oxidation performed on carbon felt. The aromatic compounds 2-hydroxy-4-(N-acetyl) aminophenol, 1,4-benzoquinone, benzaldehyde and benzoic acid were identified as toxic sub-products during the first stage of the electrochemical treatment, whereas aliphatic short-chain carboxylic acids (oxalic, maleic, oxamic, formic, acetic and fumaric acids) and inorganic ions (ammonium and nitrate) were well identified as non-toxic terminal sub-products. Electrogenerated hydroxyl radicals then converted the eco-toxic and bio-refractory property of initial ACE molecule (500 mL, 1 mM) and subsequent aromatic sub-products into non-toxic compounds after 2 h of EF treatment. The toxicity of every intermediate produced during the mineralization of ACE was quantified, and a relationship was established between the degradation pathway of ACE and the global toxicity evolution of the solution. After 8 h of treatment, a total organic carbon removal of 86.9% could be reached for 0.1 mM ACE at applied current of 500 mA with 0.2 mM of Fe²⁺ used as catalyst.

Paclitaxel resistance development is associated with biphasic changes in reactive oxygen species, mitochondrial membrane potential and autophagy with elevated energy production capacity in lung cancer cells: A chronological study

Paclitaxel (Tx) is one of the first-line chemotherapeutic drugs used against lung cancer, but acquired resistance to this drug is a major challenge against successful chemotherapy. In this work, we have focused on the chronological changes of various cellular parameters and associated effect on Tx (10 nM) resistance development in A549 cell line. It was observed, at initial stage, the cell death percentage due to drug treatment had increased up to 20 days, and thereafter, it started declining and became completely resistant by 40 days. Expressions of βIII tubulin and drug efflux pumps also increased over the period of resistance development. Changes in cellular autophagy and reactive oxygen species generation showed a biphasic pattern and increased gradually over the course of upto 20 days, thereafter declined gradually; however, their levels remained higher than untreated cells when resistance was acquired. Increase in extracellular acidification rates and oxygen consumption rates was found to be directly correlated with acquisition of resistance. The depolarisation of mitochondrial membrane potential was also biphasic; first, it increased with increase of cell death up to 20 days, thereafter, it gradually decreased to normal level along with resistance development. Increase in activity of catalase, glutathione peroxidase and glutathione content over these periods may attribute in bringing down the reactive oxygen species levels and normalisation of mitochondrial membrane potential in spite of comparatively higher reactive oxygen species production by the Tx-resistant cells.

MiR-34a, a promising novel biomarker for benzene toxicity, is involved in cell apoptosis triggered by 1,4-benzoquinone through targeting Bcl-2

Exposure to benzene is inevitable, and concerns regarding the adverse health effects of benzene have been raised. Most investigators found that benzene exposure induced hematotoxicity. In this regard, Our study aimed to explore a novel potential biomarker of adverse health effects following benzene exposure and the toxic mechanisms of benzene metabolites in vitro. This study consisted of 314 benzene-exposed workers and 288 control workers, an air benzene concentration of who were 2.64 ± 1.60 mg/m³ and 0.05 ± 0.01 mg/m³, respectively. In this population-based study, miR-34a expression was elevated in benzene-exposed workers. The correlation of miR-34a with the airborne benzene concentration, S-phenylmercapturic acid (S-PMA) and trans, trans-muconic acid (t, t-MA), all of which reflect benzene exposure, was found. Correlation analysis indicated that miR-34a was associated with peripheral blood count, alanine transaminase (ALT) and oxidative stress. Furthermore, multivariate analysis demonstrated that miR-34a expression was strongly associated with white blood cell count (structure loadings = 0.952). In population-based study, miR-34a had the largest contribution to altered peripheral blood counts, which reflect benzene-induced hematotoxicity. The role of miR-34a in benzene toxicity was assessed using lentiviral vector transfection. Results revealed that 1,4-benzoquinone induced abnormal cell apoptosis and simultaneously upregulated miR-34a accompanied with decreased Bcl-2. Finally, inhibition of miR-34a elevated Bcl-2 and decreased 1,4-benzoquinone-induced apoptosis. In conclusion, miR-34a was observed to be involved in benzene-induced hematotoxicity by targeting Bcl-2 and could be regarded as a potential novel biomarker for benzene toxicity.

MiR-133a regarded as a potential biomarker for benzene toxicity through targeting Caspase-9 to inhibit apoptosis induced by benzene metabolite (1,4-Benzoquinone)

Benzene is an environmental and industrial chemical which is widely utilized in various applications. Our previous study showed that miR-133a expression was down-regulated in chronic benzene poisoning workers, but the mechanism of miR-133a in benzene-induced hematotoxicity remains unclear. In this population-based study, benzene-exposed group recruited workers whose concentration of air benzene was 3.50±1.60mg/m(3), and control workers who were exposed to 0.06±0.01mg/m(3) air benzene. By comparison, Caspase-9 and Caspase-3 was up-regulated while miR-133a expression decreased in benzene-exposed workers. Pearson correlation analysis showed that miR-133a was reversely correlated with pro-apoptotic gene Caspase-9 in population-based study. Moreover, multiple linear regressions indicated that miR-133a was positively associated with blood cells count. To explore the underlying mechanism of miR-133a in benzene-induced hematotoxicity, AO/EB staining and TEM ultrastructural analysis were conducted to verify the activation of apoptosis in Human Leukemic U937 Cells induced by benzene metabolites (1,4-Benzoquinone, 1,4-BQ), while the mechanism of miR-133a in 1,4-BQ-induced apoptosis was performed using lentivirus vectors transfection. The results demonstrated that 1,4-BQ evidently induced mitochondria-mediated apoptosis and increased pro-apoptotic genes (Caspase-9 and Caspase-3) expression in a dose-dependent manner. The mechanistic study showed 1,4-BQ decreased miR-133a expression and miR-133a over-expression attenuated 1, 4-BQ-caused upregulation of Caspase-9, Caspase-3 and apoptosis. In conclusion, our research suggested that benzene induced hematotoxicity by decreasing miR-133a and caspase-dependent apoptosis which might contribute to the underlying mechanism of miR-133a in benzene-induced hematotoxicity.

Toxicity removal assessments related to degradation pathways of azo dyes: Toward an optimization of Electro-Fenton treatment

The degradation pathway of Acid Orange 7 (AO7) by Electro-Fenton process using carbon felt cathode was investigated via HPLC-UV and LC-MS, IC, TOC analysis and bioassays (Vibrio Fischeri 81.9% Microtox(®) screening tests). The TOC removal of AO7 reached 96.2% after 8 h treatment with the optimal applied current density at -8.3 mA cm(-2) and 0.2 mM catalyst concentration. The toxicity of treated solution increased rapidly to its highest value at the early stage of electrolysis (several minutes), corresponding to the formation of intermediate poisonous aromatic compounds such as 1,2-naphthaquinone (NAPQ) and 1,4-benzoquinone (BZQ). Then, the subsequent formation of aliphatic short-chain carboxylic acids like acetic acid, formic acid, before the complete mineralization, leaded to a non-toxic solution after 270 min for 500 mL of AO7 (1 mM). Moreover, a quantitative analysis of inorganic ions (i.e. ammonium, nitrate, sulfate) produced during the course of degradation could help to verify molar balance with regard to original nitrogen and sulfur elements. To conclude, a clear degradation pathway of AO7 was proposed, and could further be applied to other persistent pharmaceuticals in aquatic environment.

Effects of controlled diesel exhaust exposure on apoptosis and proliferation markers in bronchial epithelium - an in vivo bronchoscopy study on asthmatics, rhinitics and healthy subjects

BACKGROUND

Epidemiological evidence demonstrates that exposure to traffic-derived pollution worsens respiratory symptoms in asthmatics, but controlled human exposure studies have failed to provide a mechanism for this effect. Here we investigated whether diesel exhaust (DE) would induce apoptosis or proliferation in the bronchial epithelium in vivo and thus contribute to respiratory symptoms.

METHODS

Moderate (n = 16) and mild (n = 16) asthmatics, atopic non-asthmatic controls (rhinitics) (n = 13) and healthy controls (n = 21) were exposed to filtered air or DE (100 μg/m(3)) for 2 h, on two separate occasions. Bronchial biopsies were taken 18 h post-exposure and immunohistochemically analysed for pro-apoptotic and anti-apoptotic proteins (Bad, Bak, p85 PARP, Fas, Bcl-2) and a marker of proliferation (Ki67). Positive staining was assessed within the epithelium using computerized image analysis.

RESULTS

No evidence of epithelial apoptosis or proliferation was observed in healthy, allergic or asthmatic airways following DE challenge.

CONCLUSION

In the present study, we investigated whether DE exposure would affect markers of proliferation and apoptosis in the bronchial epithelium of asthmatics, rhinitics and healthy controls, providing a mechanistic basis for the reported increased airway sensitivity in asthmatics to air pollutants. In this first in vivo exposure investigation, we found no evidence of diesel exhaust-induced effects on these processes in the subject groups investigated.

1,4-benzoquinone-induced STAT-3 hypomethylation in AHH-1 cells: Role of oxidative stress

Benzene, a known occupational and environmental contaminant, is associated with increased risk of leukemia. The objectives of this study were to elucidate the regulatory mechanism of the hypomethylated STAT3 involved in benzene toxicity in vitro. As 1,4-benzoquinone (1,4-BQ) is one of benzene’s major toxic metabolites, AHH-1 cells were treated by 1,4-BQ for 24 h with or without pretreatment of the antioxidant a-LA or the methyltransferase inhibitor, 5-aza-2′ deoxycytidine (5-aza). The cell viability was investigated using the 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. ROS was determined via 2′,7′-dichlorodihydrofluorescein diacetate (DCFDA) flow cytometric assays. The level of oxidative stress marker 8-OHdG was measured by enzyme-linked immunosorbent assay. Methylation-specific PCR was used to detect the methylation status of STAT3. Results indicated the significantly increasing expression of ROS and 8-OHdG which accompanied with STAT3 hypomethylation in 1,4-BQ-treated AHH-1 cells. α-LA suppressed the expression of both ROS and 8-OHdG, simultaneously reversed 1,4-BQ-induced STAT3 hypomethylation. However, although the methylation inhibitor, 5-aza reduced the expression level of ROS and 8-OHdG, but had no obvious inhibiting effect on STAT3 methylation level. Taken together, oxidative stress are involved 1,4-BQ-induced STAT3 methylation expression.

Reversal of SIN-1-induced eNOS dysfunction by the spin trap, DMPO, in bovine aortic endothelial cells via eNOS phosphorylation

BACKGROUND AND PURPOSE

Nitric oxide (NO) derived from eNOS is mostly responsible for the maintenance of vascular homeostasis and its decreased bioavailability is characteristic of reactive oxygen species (ROS)-induced endothelial dysfunction (ED). Because 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), a commonly used spin trap, can control intracellular nitroso-redox balance by scavenging ROS and donating NO, it was employed as a cardioprotective agent against ED but the mechanism of its protection is still not clear. This study elucidated the mechanism of protection by DMPO against SIN-1-induced oxidative injury to bovine aortic endothelial cells (BAEC).

EXPERIMENTAL APPROACH

BAEC were treated with SIN-1, as a source of peroxynitrite anion (ONOO⁻), and then incubated with DMPO. Cytotoxicity following SIN-1 alone and cytoprotection by adding DMPO was assessed by MTT assay. Levels of ROS and NO generation from HEK293 cells transfected with wild-type and mutant eNOS cDNAs, tetrahydrobiopterin bioavailability, eNOS activity, eNOS and Akt kinase phosphorylation were measured.

KEY RESULTS

Post-treatment of cells with DMPO attenuated SIN-1-mediated cytotoxicity and ROS generation, restoration of NO levels via increased in eNOS activity and phospho-eNOS levels. Treatment with DMPO alone significantly increased NO levels and induced phosphorylation of eNOS Ser¹¹⁷⁹ via Akt kinase. Transfection studies with wild-type and mutant human eNOS confirmed the dual role of eNOS as a producer of superoxide anion (O₂⁻) with SIN-1 treatment, and a producer of NO in the presence of DMPO.

CONCLUSION AND IMPLICATIONS

Post-treatment with DMPO of oxidatively challenged cells reversed eNOS dysfunction and could have pharmacological implications in the treatment of cardiovascular diseases.

Inhibition of autophagy by chloroquine potentiates synergistically anti-cancer property of artemisinin by promoting ROS dependent apoptosis

Artemisinin (ART) is a well-known anti-malarial drug, and recently it is shown prospective to selectively kill cancer cells. But low potency makes it inappropriate for use as an anticancer drug. In this study, we modulated the ART-induced autophagy to increase Potency of ART as an anticancer agent. ART reduced the cell viability and colony forming ability of non-small lung carcinoma (A549) cells and it was non-toxic against normal lung (WI38) cells. ART induced autophagy at the early stage of treatment. Pre-treatment with chloroquine (CQ) and followed by ART treatment had synergistic combination index (CI) for cell death. Inhibition of autophagy by CQ pre-treatment led to accumulation of acidic vacuoles (AVOs) which acquainted with unprocessed damage mitochondria that subsequently promoted ROS generation, and resulted releases of Cyt C in cytosol that caused caspase-3 dependent apoptosis cell death in ART-treated A549 cells. Scavenging of ROS by antioxidant N-acetyl-cysteine (NAC) inhibited caspase-3 activity and rescued the cells from apoptosis. Similar effects were observed in other cancer cells SCC25 and MDA-MB-231. The appropriate manipulation of autophagy by using CQ provides a powerful strategy to increase the Potency of selective anticancer property of ART.

Quinone-induced protein handling changes: implications for major protein handling systems in quinone-mediated toxicity

Para-quinones such as 1,4-Benzoquinone (BQ) and menadione (MD) and ortho-quinones including the oxidation products of catecholamines, are derived from xenobiotics as well as endogenous molecules. The effects of quinones on major protein handling systems in cells; the 20/26S proteasome, the ER stress response, autophagy, chaperone proteins and aggresome formation, have not been investigated in a systematic manner. Both BQ and aminochrome (AC) inhibited proteasomal activity and activated the ER stress response and autophagy in rat dopaminergic N27 cells. AC also induced aggresome formation while MD had little effect on any protein handling systems in N27 cells. The effect of NQO1 on quinone induced protein handling changes and toxicity was examined using N27 cells stably transfected with NQO1 to generate an isogenic NQO1-overexpressing line. NQO1 protected against BQ-induced apoptosis but led to a potentiation of AC- and MD-induced apoptosis. Modulation of quinone-induced apoptosis in N27 and NQO1-overexpressing cells correlated only with changes in the ER stress response and not with changes in other protein handling systems. These data suggested that NQO1 modulated the ER stress response to potentiate toxicity of AC and MD, but protected against BQ toxicity. We further demonstrated that NQO1 mediated reduction to unstable hydroquinones and subsequent redox cycling was important for the activation of the ER stress response and toxicity for both AC and MD. In summary, our data demonstrate that quinone-specific changes in protein handling are evident in N27 cells and the induction of the ER stress response is associated with quinone-mediated toxicity.

A quantitative toxicogenomics assay reveals the evolution and nature of toxicity during the transformation of environmental pollutants

The incomplete mineralization of contaminants of emerging concern (CECs) during the advanced oxidation processes can generate transformation products that exhibit toxicity comparable to or greater than that of the original contaminant. In this study, we demonstrated the application of a novel, fast, and cost-effective quantitative toxicogenomics-based approach for the evaluation of the evolution and nature of toxicity along the electro-Fenton oxidative degradation of three representative CECs whose oxidative degradation pathways have been relatively well studied, bisphenol A, triclosan, and ibuprofen. The evolution of toxicity as a result of the transformation of parent chemicals and production of intermediates during the course of degradation are monitored, and the quantitative toxicogenomics assay results revealed the dynamic toxicity changes and mechanisms, as well as their association with identified intermediates during the electro-Fenton oxidation process of the selected CECs. Although for the three CECs, a majority (>75%) of the parent compounds disappeared at the 15 min reaction time, the nearly complete elimination of toxicity required a minimal 30 min reaction time, and they seem to correspond to the disappearance of identified aromatic intermediates. Bisphenol A led to a wide range of stress responses, and some identified transformation products containing phenolic or quinone group, such as 1,4-benzoquinone and hydroquinone, likely contributed to the transit toxicity exhibited as DNA stress (genotoxicity) and membrane stress during the degradation. Triclosan is known to cause severe oxidative stress, and although the oxidative damage potential decreased concomitantly with the disappearance of triclosan after a 15 min reaction, the sustained toxicity associated with both membrane and protein stress was likely attributed at least partially to the production of 2,4-dichlorophenol that is known to cause the production of abnormal proteins and affect the cell membrane. Ibuprofen affects the cell transporter function and exhibited significantly high membrane stress related to both membrane structure and function. Oxidative degradation of ibuprofen led to a shift in its toxicity profile from mainly membrane stress to one that exhibited not only sustained membrane stress but also protein stress and DNA stress. The information-rich and high-resolution toxicogenomics results served as "fingerprints" that discerned and revealed the toxicity mechanism at the molecular level among the CECs and their oxidation transformation products. This study demonstrated that the quantitative toxicogenomics assay can serve as a useful tool for remediation technology efficacy assessment and provide guidance about process design and optimization for desired toxicity elimination and risk reduction.

Depleted energy charge and increased pulmonary endothelial permeability induced by mitochondrial complex I inhibition are mitigated by coenzyme Q1 in the isolated perfused rat lung

Mitochondrial dysfunction is associated with various forms of lung injury and disease that also involve alterations in pulmonary endothelial permeability, but the relationship, if any, between the two is not well understood. This question was addressed by perfusing isolated intact rat lung with a buffered physiological saline solution in the absence or presence of the mitochondrial complex I inhibitor rotenone (20 μM). Compared to control, rotenone depressed whole lung tissue ATP from 5.66 ± 0.46 (SEM) to 2.34 ± 0.15 µmol · g(-1) dry lung, with concomitant increases in the ADP:ATP and AMP:ATP ratios. Rotenone also increased lung perfusate lactate (from 12.36 ± 1.64 to 38.62 ± 3.14 µmol · 15 min(-1) perfusion · g(-1) dry lung) and the lactate:pyruvate ratio, but had no detectable impact on lung tissue GSH:GSSG redox status. The amphipathic quinone coenzyme Q1 (CoQ1; 50 μM) mitigated the impact of rotenone on the adenine nucleotide balance, wherein mitigation was blocked by NAD(P)H-quinone oxidoreductase 1 or mitochondrial complex III inhibitors. In separate studies, rotenone increased the pulmonary vascular endothelial filtration coefficient (Kf) from 0.043 ± 0.010 to 0.156 ± 0.037 ml · min(-1) · cm H2O(-1) · g(-1) dry lung, and CoQ1 protected against the effect of rotenone on Kf. A second complex I inhibitor, piericidin A, qualitatively reproduced the impact of rotenone on Kf and the lactate:pyruvate ratio. Taken together, the observations imply that pulmonary endothelial barrier integrity depends on mitochondrial bioenergetics as reflected in lung tissue ATP levels and that compensatory activation of whole lung glycolysis cannot protect against pulmonary endothelial hyperpermeability in response to mitochondrial blockade. The study further suggests that low-molecular-weight amphipathic quinones may have therapeutic utility in protecting lung barrier function in mitochondrial insufficiency.

Stable and potent analogues derived from the modification of the dicarbonyl moiety of curcumin

Curcumin has shown promising therapeutic utilities for many diseases, including cancer; however, its clinical application is severely limited because of its poor stability under physiological conditions. Here we find that curcumin also loses its activity instantaneously in a reducing environment. Curcumin can exist in solution as a tautomeric mixture of keto and enol forms, and the enol form was found to be responsible for the rapid degradation of the compound. To increase the stability of curcumin, several analogues were synthesized in which the diketone moiety of curcumin was replaced by isoxazole (compound 2) and pyrazole (compound 3) groups. Isoxazole and pyrazole curcumins were found to be extremely stable at physiological pH, in addition to reducing atmosphere, and they can kill cancer cells under serum-depleted condition. Using molecular modeling, we found that both compounds 2 and 3 could dock to the same site of tubulin as the parent molecule, curcumin. Interestingly, compounds 2 and 3 also show better free radical scavenging activity than curcumin. Altogether, these results strongly suggest that compounds 2 and 3 could be good replacements for curcumin in future drug development.

Smokeless tobacco extract (STE)-induced toxicity in mammalian cells is mediated by the disruption of cellular microtubule network: a key mechanism of cytotoxicity

Smokeless tobacco usage is a growing public health problem worldwide. The molecular mechanism(s) underlying smokeless tobacco associated tissue damage remain largely unidentified. In the present study we have tried to explore the effects of aqueous extract of smokeless tobacco (STE) on tubulin-microtubule, the major cytoskeleton protein that maintains cells morphology and participates in cell division. Exposure to STE resulted in dose-dependent cytotoxicity in a variety of mammalian transformed cell lines such as human lung epithelial cells A549, human liver epithelial cells HepG2, and mouse squamous epithelial cells HCC7, as well as non-tumorogenic human peripheral blood mononuclear cells PBMC. Cellular morphology of STE-treated cells was altered and the associated disruption of microtubule network indicates that STE targets tubulin-microtubule system in both cell lines. Furthermore it was also observed that STE-treatment resulted in the selective degradation of cellular tubulin, whereas actin remains unaltered. In vitro, polymerization of purified tubulin was inhibited by STE with the IC₅₀ value∼150 µg/ml and this is associated with the loss of reactive cysteine residues of tubulin. Application of thiol-based antioxidant N-acetyl cysteine (NAC) significantly abrogates STE-mediated microtubule damage and associated cytotoxicity in both A549 and HepG2 cells. These results suggest that microtubule damage is one of the key mechanisms of STE-induced cytotoxity in mammalian cells.

A second-generation 2-Methoxyestradiol prodrug is effective against Barrett's adenocarcinoma in a mouse xenograft model

2-Methoxyestradiol (2-ME2) is an endogenous metabolite of estradiol. In preclinical models, 2-ME2 is effective against different types of tumors. Unfortunately, only low systemic concentrations of 2-ME2 can be achieved following oral administration, even after very high doses are administered to patients. In an effort to solve this problem, we have now synthesized and tested a new prodrug of 2-ME2 that is water-soluble due to a bioreversible hydrophilic group added at the 3-position and that more effectively resists metabolic inactivation due to an ester moiety added to mask the 17-position alcohol. We are reporting here for the first time that this double prodrug of 2-ME2 is effective as an antiproliferative and anticancer agent for both in vitro and in vivo studies against Barrett esophageal adenocarcinoma (BEAC) and provided greater potency than 2-ME2 in inhibiting the growth of BEAC xenografts. Finally, studies indicate that, like 2-ME2, the 2-ME2-PD1 exhibits anticancer effect through possible disruption of microtubule network.

Diesel exhaust particles induce aberrant alveolar epithelial directed cell movement by disruption of polarity mechanisms

Disruption of the respiratory epithelium contributes to the progression of a variety of respiratory diseases that are aggravated by exposure to air pollutants, specifically traffic-based pollutants such as diesel exhaust particles (DEP). Recognizing that lung repair following injury requires efficient and directed alveolar epithelial cell migration, this study's goal was to understand the mechanisms underlying alveolar epithelial cells response to DEP, particularly when exposure is accompanied with comorbid lung injury. Separate mechanistic steps of directed migration were investigated in confluent murine LA-4 cells exposed to noncytotoxic concentrations (0-100 μg/cm(2)) of either automobile-emitted diesel exhaust particles (DEP(A)) or carbon black (CB) particles. A scratch wound model ascertained how DEP(A) exposure affected directional cell migration and BCECF ratio fluorimetry-monitored intracellular pH (pHi). Cells were immunostained with giantin to assess cell polarity, and with paxillin to assess focal cell adhesions. Cells were immunoblotted for ezrin/radixin/moesin (ERM) to assess cytoskeletal anchoring. Data demonstrate herein that exposure of LA-4 cells to DEP(A) (but not CB) resulted in delayed directional cell migration, impaired de-adhesion of the trailing edge cell processes, disrupted regulation of pHi, and altered Golgi polarity of leading edge cells, along with modified focal adhesions and reduced ERM levels, indicative of decreased cytoskeletal anchoring. The ability of DEP(A) to disrupt directed cell migration at multiple levels suggests that signaling pathways such as ERM/Rho are critical for transduction of ion transport signals into cytoskeletal arrangement responses. These results provide insights into the mechanisms by which chronic exposure to traffic-based emissions may result in decrements in lung capacity.

Molecular and cellular mechanisms of cigarette smoke-induced myocardial injury: prevention by vitamin C

BACKGROUND

Cardiovascular disease (CVD) remains one of the major killers in modern society. One strong risk factor of CVD is cigarette smoking that causes myocardial injury and leads to the genesis of pathological cardiovascular events. However, the exact toxic component(s) of cigarette smoke (CS) and its molecular and cellular mechanisms for causing myocardial injury leading to heart damage and its prevention are largely unknown.

METHODOLOGY/PRINCIPAL FINDINGS

Using a guinea pig model, here we show that chronic exposure to CS produces myocardial injury that is prevented by vitamin C. Male guinea pigs were fed either vitamin C-deficient (0.5 mg/day) or vitamin C-sufficient (15 mg/day) diet and subjected to CS exposure from 5 Kentucky Research cigarettes (3R4F)/day (6 days/week) in a smoke chamber up to 8 weeks. Pair-fed sham controls were subjected to air exposure instead of CS exposure under similar conditions. Myocardial injury was produced in CS-exposed marginal vitamin C-deficient guinea pigs as evidenced by release of cardiac Troponin-T and I in the serum, oxidative stress, inflammation, apoptosis, thrombosis and collagen deposition in the myocardium. Treatment of rat cardiomyocyte cells (H9c2) in vitro and guinea pigs in vivo with p-benzoquinone (p-BQ) in amounts derived from CS revealed that p-BQ was a major factor responsible for CS-induced myocardial damage. A moderately large dose of vitamin C (15 mg/day) prevented CS/p-BQ-induced myocardial injury. Population based studies indicated that plasma vitamin C levels of smokers without disease were significantly lower (p = 0,0000) than that of non-smokers. Vitamin C levels of CS-related cardiovascular patients were further lower (p = 0.0000) than that of smokers without disease.

CONCLUSIONS/SIGNIFICANCE

The results indicate that dietary supplementation of vitamin C may be a novel and simple therapy for the prevention of pathological cardiovascular events in habitual smokers.

Inhibition of ROS-induced apoptosis in endothelial cells by nitrone spin traps via induction of phase II enzymes and suppression of mitochondria-dependent pro-apoptotic signaling

Oxidative stress is the main etiological factor behind the pathogenesis of various diseases including inflammation, cancer, cardiovascular and neurodegenerative disorders. Due to the spin trapping abilities and various pharmacological properties of nitrones, their application as therapeutic agent has been gaining attention. Though the antioxidant properties of the nitrones are well known, the mechanism by which they modulate the cellular defense machinery against oxidative stress is not well investigated and requires further elucidation. Here, we have investigated the mechanisms of cytoprotection of the nitrone spin traps against oxidative stress in bovine aortic endothelial cells (BAEC). Cytoprotective properties of both the cyclic nitrone 5,5-dimethyl-pyrroline N-oxide (DMPO) and linear nitrone α-phenyl N-tert-butyl nitrone (PBN) against H₂O₂-induced cytotoxicity were investigated. Preincubation of BAEC with PBN or DMPO resulted in the inhibition of H₂O₂-mediated cytotoxicity and apoptosis. Nitrone-treatment resulted in the induction and restoration of phase II antioxidant enzymes via nuclear translocation of NF-E2-related factor 2 (Nrf-2) in oxidatively-challenged cells. Furthermore, the nitrones were found to inhibit the mitochondrial depolarization and subsequent activation of caspase-3 induced by H₂O₂. Significant down-regulation of the pro-apoptotic proteins p53 and Bax, and up-regulation of the anti-apoptotic proteins Bcl-2 and p-Bad were observed when the cells were preincubated with the nitrones prior to H₂O₂-treatment. It was also observed that Nrf-2 silencing completely abolished the protective effects of nitrones. Hence, these findings suggest that nitrones confer protection to the endothelial cells against oxidative stress by modulating phase II antioxidant enzymes and subsequently inhibiting mitochondria-dependent apoptotic cascade.

Whole cigarette smoke promotes human gingival epithelial cell apoptosis and inhibits cell repair processes

BACKGROUND AND OBJECTIVE

Smoking cigarettes increases the risk of developing various types of human diseases, including cancers and periodontitis. As gingival epithelial cells are known to play an active role in innate immunity via the secretion of a wide variety of mediators, and as these cells are the first ones exposed to environmental stimuli such as cigarette smoke, we sought to investigate the effects of whole cigarette smoke on normal human gingival epithelial cells and tissue.

MATERIAL AND METHODS

Human gingival epithelial cells were extracted from healthy nonsmokers and used either as a monolayer or as an engineered human oral mucosa to investigate the effect of whole cigarette smoke on cell growth, apoptosis and wound repair/migration.

RESULTS

Our findings show that when gingival epithelial cells were exposed once to whole cigarette smoke, this resulted in a significant inhibition of cell growth through an apoptotic pathway, as confirmed by an increase of Bax and a decrease of Bcl-xL and caspase-3 activity. Cigarette smoke also inhibited epithelial cell migration. These effects may explain the disorganization of the engineered human oral mucosa tissue when exposed to whole cigarette smoke.

CONCLUSION

Exposure to whole cigarette smoke markedly inhibits epithelial cell growth through an apoptosis/necrosis pathway that involves Bax and Bcl-xL proteins and caspase-3 activity. Cigarette smoke also disrupts epithelial cell migration, which may negatively affect periodontal wound healing.