Lifespan of etoposide-treated human neutrophils is affected by antioxidant ability of quercetin

Dietary Quercetin Alleviated DSS-induced Colitis in Mice Through Several Possible Pathways by Transcriptome Analysis

BACKGROUND

The prevalence of inflammatory bowel disease is rapidly increasing around the world. Quercetin is a flavonoid commonly found in vegetables and fruits and has been reported to exert numerous pharmacological activities such as enhancing antioxidant capacity or suppressing inflammation.

OBJECTIVE

We aimed to explore whether quercetin was effective for IBD and the underlying mechanism of quercetin for the ameliorative effects on the DSS-induced colitis in mice.

METHODS

Thirty-six mice were randomly assigned to three treatments, including the control group (Ctr), DSS-induced colitis group (DSS) and DSS-induced colitis supplemented with 500 ppm quercetin (DQ500). Colitis was induced by DSS intake, and body weight was recorded every day. After six days administration of DSS, intestinal permeability was measured, and the liver was taken for antioxidant enzyme tests. Colonic tissue was taken for the histopathlogical score and RNA-sequencing analysis.

RESULTS

In this experiment, dietary quercetin for 500ppm alleviated the DSS-induced colitis, possibly by strengthening intestinal integrity, liver antioxidant capacity. Based on the results of the transcriptome of colon tissue, several key genes were modulated by quercetin. ERK1/2-FKBP pathway and RXR-STAT3 pathway were involved in the development of IBD, furthermore, in the down-regulation of S100a8/9, FBN2 contributed to lowering the risk of colongenesis.

CONCLUSION

We demonstrated that dietary quercetin alleviated the DSS-induced colitis in mice. This is most likely due to its beneficial effects on intestinal integrity and modulation of several key pathways. Based on our research, quercetin was a promising candidate for IBD and its pharmaceutical effects on both IBD and colongenesis need further research.

High-Content Screening Identifies Vanilloids as a Novel Class of Inhibitors of NET Formation

Neutrophils migrate to sites of infection where they phagocytose, degranulate, and/or, in the presence of appropriate stimuli, release decondensed chromatin strands (called neutrophil extracellular traps, NETs) for trapping and possibly killing microorganisms. NET formation is characterized by marked morphological cell changes, in particular within the nucleus. Lytic NET formation can be observed in neutrophils undergoing cell death, which is referred to as NETosis. Dysregulation of NET production and/or degradation can exert pathogenic effects, contributing to the pathogenesis of various diseases, including cystic fibrosis, autoimmune diseases and inflammatory conditions. By employing a phenotypic assay based on high-content imaging and analysis, we screened a library of biologically active compounds and identified vanilloids as a novel class of chemical compounds able to hinder NETosis induction and NET release. Vanilloids also markedly decrease cytosolic ROS production. The identification of novel vanilloid NET inhibitors, able to stop excessive or aberrant NET production might offer new therapeutic options for those disorders displaying NET overproduction.

A Flow Cytometry-Based Assay for High-Throughput Detection and Quantification of Neutrophil Extracellular Traps in Mixed Cell Populations

Neutrophil extracellular traps (NETs) are web‐like structures composed of decondensed chromatin and antimicrobial proteins that are released into the extracellular space during microbial infections. This active cell death program is known as NETosis. To date, florescence microscopy is the widely accepted method for visualization and quantification of NETs. However, this method is subjective, time consuming and yields low numbers of analyzed polymorphonuclear cells (PMNs) per sample. Increasing interest has emerged on the identification of NETs using flow cytometry techniques. However, flow cytometry analysis of NETs requires particular precautions for sample preparation to obtain reproducible data. Herein, we describe a flow cytometry‐based assay for high‐throughput detection and quantification of NETosis in mixed cell populations. We used fluorescent‐labeled antibodies against cell markers on PMNs together with a combination of nucleic acid stains to measure NETosis in whole blood (WB) and purified PMNs. Using plasma membrane‐impermeable DNA‐binding dye, SYTOX Orange (SO), we found that cell‐appendant DNA of NETting PMNs were positive for SO and DAPI. The combination of optimally diluted antibody and nucleic acid dyes required no washing and yielded low background fluorescence. Significant correlations were found for NETosis from WB and purified PMNs. We then validated the assay by comparing with time‐lapse live cell fluorescence microscopy and determined very good intraassay and interassay variances. The assay was then applied to a disease associated with NETosis, systemic lupus erythematosus (SLE). We examined PMA‐induced NETosis in peripheral PMNs from SLE patients and controls and in bone marrow PMNs from multiple murine models. In summary, this assay is observer‐independent and allows for rapid assessment of a large number of PMNs per sample. Use of this assay does not require sophisticated microscopic equipment like imaging flow cytometers and may be a starting point to analyze extracellular trap formation from immune cells other than PMNs. © 2018 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.

p38 but not p53 is responsible for UVA-induced MCPIP1 expression

MCPIP1 (Monocyte Chemotactic Protein-1 Induced Protein) is an important regulator of inflammation and cell apoptosis, but its role in UVA-induced stress response in the epidermis has never been studied. We have found that moderate apoptosis-inducing dose of UVA (27J/cm²) increases the level of MCPIP1 expression in HaCaT cells and normal human keratinocytes (NHEK) within 6-9h after the treatment. MCPIP1 upregulation was dependent on the induction of p38, but not p53, as demonstrated by using p38 inhibitor SB203580 and p53 inducer RG7388, respectively. This increase was also blocked by antioxidants (α-tocopherol and ascorbic acid), suggesting the involvement of MCPIP1 in UVA-induced oxidative stress response. Si-RNA-mediated down-regulation of MCPIP1 expression in HaCaT cells resulted in increased sensitivity to UVA-induced DNA damage and apoptosis. This was accompanied by decreased phosphorylation of p53 and p38 in MCPIP1-silenced cells following UVA irradiation. The activation of p38 in response to low doses of ultraviolet radiation was postulated to be protective for p53-inactive cells. Therefore, MCPIP1 may favor the survival of p53-defective HaCaT cells by sustaining the activation of p38. This creates a loop of mutual positive regulation between p38 and MCPIP1 protein in HaCaT cells, providing the protection against the consequences of UVA irradiation.

Propofol suppresses LPS-induced nuclear accumulation of HIF-1α and tumor aggressiveness in non-small cell lung cancer

Tumor hypoxia has been recognized as a characteristic of the tumor microenvironment and promotes metastasis in a variety of types of cancer. However, in lung cancer, the role of hypoxia-inducible factor 1α (HIF-1α) in modulating the cellular response to the inflammation-related microenvironment remains unclear. In the present study, enhanced expression of HIF-1α accompanied by an increased ROS level was observed in lipopolysaccharide (LPS)-stimulated non-small cell lung cancer (NSCLC) cells. In addition, propofol, a general anesthetic, was found to significantly reduce the LPS-induced upregulation of HIF-1α and ROS in a dose-dependent manner. Further study showed that propofol may antagonize the role of LPS in activating HIF-1α through attenuating the protein stability and nuclear localization of HIF-1α. Moreover, knockdown of HIF-1α attenuated expression of mesenchymal marker, vimentin, but promoted the expression of epidermal marker, E-cadherin, in the LPS-treated NSCLC cells. Notably, LPS-induced epithelial-to-mesenchymal transition (EMT) was notably suppressed by propofol treatment. Consistently, a wound healing assay revealed that propofol abrogated LPS-stimulated migration of NSCLC cells while overexpression of HIF-1α reversed the effects of propofol. Similarly, we investigated the influence of propofol on the invasive capability of NSCLC cells. Western blot and RT-PCR analyses indicated that both knockdown of HIF-1α and treatment of propofol attenuated the LPS-activated expression of MMP2 and MMP9 which are necessary for tumor invasion. However, results from the Transwell assay confirmed that propofol also suppressed cell invasion by decreasing HIF-1α expression in the LPS-treated NSCLC cells. Analysis of clinical specimens demonstrated abnormal expression of HIF-1α in NSCLC tissues and a poor prognosis in patients with elevated HIF-1α expression. Thus, the present study suggests a potential strategy for NSCLC by targeting HIF-1α.

Caffeine affects the biological responses of human hematopoietic cells of myeloid lineage via downregulation of the mTOR pathway and xanthine oxidase activity

Correction of human myeloid cell function is crucial for the prevention of inflammatory and allergic reactions as well as leukaemia progression. Caffeine, a naturally occurring food component, is known to display anti-inflammatory effects which have previously been ascribed largely to its inhibitory actions on phosphodiesterase. However, more recent studies suggest an additional role in affecting the activity of the mammalian target of rapamycin (mTOR), a master regulator of myeloid cell translational pathways, although detailed molecular events underlying its mode of action have not been elucidated. Here, we report the cellular uptake of caffeine, without metabolisation, by healthy and malignant hematopoietic myeloid cells including monocytes, basophils and primary acute myeloid leukaemia mononuclear blasts. Unmodified caffeine downregulated mTOR signalling, which affected glycolysis and the release of pro-inflammatory/pro-angiogenic cytokines as well as other inflammatory mediators. In monocytes, the effects of caffeine were potentiated by its ability to inhibit xanthine oxidase, an enzyme which plays a central role in human purine catabolism by generating uric acid. In basophils, caffeine also increased intracellular cyclic adenosine monophosphate (cAMP) levels which further enhanced its inhibitory action on mTOR. These results demonstrate an important mode of pharmacological action of caffeine with potentially wide-ranging therapeutic impact for treating non-infectious disorders of the human immune system, where it could be applied directly to inflammatory cells.

Curcumin enhances the cytogenotoxic effect of etoposide in leukemia cells through induction of reactive oxygen species

Curcumin may exert a more selective cytotoxic effect in tumor cells with elevated levels of free radicals. Here, we investigated whether curcumin can modulate etoposide action in myeloid leukemia cells and in normal cells of hematopoietic origin. HL-60 cell line, normal myeloid progenitor cluster of differentiation (CD)-34⁺ cells, and granulocytes were incubated for 4 or 24 hours at different concentrations of curcumin and/or etoposide. Brown Norway rats with acute myeloid leukemia (BNML) were used to prove the influence of curcumin on etoposide action in vivo. Rats were treated with curcumin for 23 days and etoposide was administered for the final 3 days of the experiment. Curcumin synergistically potentiated the cytotoxic effect of etoposide, and it intensified apoptosis and phosphorylation of the histone H2AX induced by this cytostatic drug in leukemic HL-60 cells. In contrast, curcumin did not significantly modify etoposide-induced cytotoxicity and H2AX phosphorylation in normal CD34⁺ cells and granulocytes. Curcumin modified the cytotoxic action of etoposide in HL-60 cells through intensification of free radical production because preincubation with N-acetyl-l-cysteine (NAC) significantly reduced the cytotoxic effect of curcumin itself and a combination of two compounds. In contrast, NAC did not decrease the cytotoxic effect of etoposide. Thus, oxidative stress plays a greater role in the cytotoxic effect of curcumin than that of etoposide in HL-60 cells. In vitro results were confirmed in a BNML model. Pretreatment with curcumin enhanced the antileukemic activity of etoposide in BNML rats (1.57-fold tumor reduction versus etoposide alone; P<0.05) and induced apoptosis of BNML cells more efficiently than etoposide alone (1.54-fold change versus etoposide alone; P<0.05), but this treatment protected nonleukemic B-cells from apoptosis. Thus, curcumin can increase the antileukemic effect of etoposide through reactive oxygen species in sensitive myeloid leukemia cells, and it is harmless to normal human cells.

The immune receptor Tim-3 mediates activation of PI3 kinase/mTOR and HIF-1 pathways in human myeloid leukaemia cells

The T-cell immunoglobulin and mucin domain 3 (Tim-3) is a plasma membrane-associated protein that is highly expressed in human acute myeloid leukaemia cells. As an acute myeloid leukaemia antigen, it could therefore be considered as a potential target for immune therapy and highly-specific drug delivery. However, a conceptual understanding of its biological role is required before consideration of this protein for therapeutic settings. Here, we reveal the detailed mechanism of action underlying the biological responses mediated by the Tim-3 receptor in myeloid cells. Our studies demonstrate that Tim-3 triggers growth factor type responses in acute myeloid leukaemia cells by activating a phosphatidylinositol-3 kinase (PI-3K)/mammalian target of rapamycin (mTOR) pathway. In addition, the receptor activates hypoxic signalling pathways upregulating glycolysis and pro-angiogenic responses. These findings suggest that Tim-3 could be used as a potential therapeutic target for immune therapy and drug delivery in human acute myeloid leukaemia cells.

Enhancement of TWIK-related acid-sensitive potassium channel 3 (TASK3) two-pore domain potassium channel activity by tumor necrosis factor α

TASK3 two-pore domain potassium (K2P) channels are responsible for native leak K channels in many cell types which regulate cell resting membrane potential and excitability. In addition, TASK3 channels contribute to the regulation of cellular potassium homeostasis. Because TASK3 channels are important for cell viability, having putative roles in both neuronal apoptosis and oncogenesis, we sought to determine their behavior under inflammatory conditions by investigating the effect of TNFα on TASK3 channel current. TASK3 channels were expressed in tsA-201 cells, and the current through them was measured using whole cell voltage clamp recordings. We show that THP-1 human myeloid leukemia monocytes, co-cultured with hTASK3-transfected tsA-201 cells, can be activated by the specific Toll-like receptor 7/8 activator, R848, to release TNFα that subsequently enhances hTASK3 current. Both hTASK3 and mTASK3 channel activity is increased by incubation with recombinant TNFα (10 ng/ml for 2-15 h), but other K2P channels (hTASK1, hTASK2, hTREK1, and hTRESK) are unaffected. This enhancement by TNFα is not due to alterations in levels of channel expression at the membrane but rather to an alteration in channel gating. The enhancement by TNFα can be blocked by extracellular acidification but persists for mutated TASK3 (H98A) channels that are no longer acid-sensitive even in an acidic extracellular environment. TNFα action on TASK3 channels is mediated through the intracellular C terminus of the channel. Furthermore, it occurs through the ASK1 pathway and is JNK- and p38-dependent. In combination, TNFα activation and TASK3 channel activity can promote cellular apoptosis.

Testing the efficacy of quercetin in mitigating bisphenol A toxicity in liver and kidney of mice

Quercetin (3,5,7,3',4'-pentahydroxy flavone) is a potent antioxidant found in various fruits and vegetables. The present investigation was an attempt to evaluate the mitigatory effect of quercetin on the damage caused by bisphenol A (BPA; 2,2-bis (4-hydroxyphenyl) propane), a well-known xenoestrogen, on liver and kidney of mice. Swiss strain adult male albino mice were orally administered with 120 and 240 mg/kg body weight (bw)/day BPA with or without quercetin (60 mg/kg bw/day) for 30 days. On the completion of the treatment period, animals were killed; organs were isolated and used for the study. Results revealed that oral administration of BPA for 30 days caused significant and dose-dependent decrease in body weight. Absolute and relative organ weights, total lipid and cholesterol contents were significantly increased in liver and kidney of mice when compared with vehicle control. BPA treatment also caused, when compared with vehicle control, a statistically significant reductions in the activities of catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase as well as in glutathione and total ascorbic acid contents; however, significant increase was found in malondialdehyde (MDA) levels. Histopathological studies revealed hepatocellular necrosis, cytoplasmic vacuolization and decrease in hepatocellular compactness in liver as well as distortion of the tubules, increased vacuolization, necrosis and disorganization of glomerulus in the kidney of BPA-treated mice. All these effects were dose-dependent. Co-treatment with quercetin (60 mg/kg bw) and BPA (low dose and high dose) alleviates the changes in body weight, as well as absolute and relative organ weights of mice. It also ameliorates the oxidative stress created by BPA by lowering MDA levels and by increasing enzymatic and nonenzymatic antioxidants as well as it brings back the normal histoarchitecture of liver and kidney of mice. The present results revealed that graded doses of BPA caused oxidative damage in liver and kidney of mice, which is mitigated by quercetin.

Chemical genetics analysis of an aniline mustard anticancer agent reveals complex I of the electron transport chain as a target

The antitumor agent 11β (CAS 865070-37-7), consisting of a DNA-damaging aniline mustard linked to an androgen receptor (AR) ligand, is known to form covalent DNA adducts and to induce apoptosis potently in AR-positive prostate cancer cells in vitro; it also strongly prevents growth of LNCaP xenografts in mice. The present study describes the unexpectedly strong activity of 11β against the AR-negative HeLa cells, both in cell culture and tumor xenografts, and uncovers a new mechanism of action that likely explains this activity. Cellular fractionation experiments indicated that mitochondria are the major intracellular sink for 11β; flow cytometry studies showed that 11β exposure rapidly induced oxidative stress, mitochondria being an important source of reactive oxygen species (ROS). Additionally, 11β inhibited oxygen consumption both in intact HeLa cells and in isolated mitochondria. Specifically, 11β blocked uncoupled oxygen consumption when mitochondria were incubated with complex I substrates, but it had no effect on oxygen consumption driven by substrates acting downstream of complex I in the mitochondrial electron transport chain. Moreover, 11β enhanced ROS generation in isolated mitochondria, suggesting that complex I inhibition is responsible for ROS production. At the cellular level, the presence of antioxidants (N-acetylcysteine or vitamin E) significantly reduced the toxicity of 11β, implicating ROS production as an important contributor to cytotoxicity. Collectively, our findings establish complex I inhibition and ROS generation as a new mechanism of action for 11β, which supplements conventional DNA adduct formation to promote cancer cell death.

Oxidative DNA Damage in Blood of CVD Patients Taking Detralex

The main goal of the work reported here was to determine the degree of oxidative/alkali-labile DNA damages in peripheral blood as well as in the blood stasis from varicose vein of (chronic venous disorder) CVD patients. Moreover, determination of the impact of Detralex usage on the level of (oxidative) DNA damages in CVD patients was evaluated as well.

The degree of oxidative DNA damages was studied in a group consisted of thirty patients with diagnosed chronic venous insufficiency (CVI) in the 2nd and 3rd degree, according to clinical state, etiology, anatomy and pathophysiology (CEAP), and qualified to surgical procedure. The control group consisted of normal volunteers (blood donors) qualified during standard examinations at Regional Centers of Blood Donation and Blood Therapy.

The comet assay was used for determination of DNA damages.

Analyses of the obtained results showed increase in the level of oxidative/alkali-labile DNA damages in lymphocytes originating from antebrachial blood of CVD patients as compared to the control group (Control) (p < 0.002; ANOVA). In addition, it was demonstrated that the usage of Detralex® resulted in decrease of the level of oxidative/alkali-labile DNA damages in CVD patients as compared to patients without Detralex® treatment (p < 0.001; ANOVA).

Based on findings from the study, it may be hypothesized about occurrence of significant oxidative DNA damages as the consequence of strong oxidative stress in CVD. In addition, antioxidative effectiveness of Detralexu® was observed at the recommended dose, one tablet twice daily.

Involvement of xanthine oxidase and hypoxia-inducible factor 1 in Toll-like receptor 7/8-mediated activation of caspase 1 and interleukin-1β

Inflammatory reactions to ssRNA viruses are induced by the endosomal Toll-like receptors (TLRs) 7 and 8. TLR7/8-mediated inflammatory reaction results in activation of the Nalp3 inflammasome via an unknown mechanism. Here we report for the first time that TLR7/8 mediate activation of xanthine oxidase (XOD) in an HIF-1α-dependent manner. XOD produces uric acid and reactive oxygen species, which could activate Nalp3 and therefore induce activation of caspase 1, known to convert inactive pro-IL-1β into active IL-1β. Specific inhibition of the XOD activity attenuates TLR7/8-mediated activation of caspase 1 and IL-1β release. These results were obtained using human THP-1 myeloid macrophages. The findings were verified by conducting in vivo experiments on mice.

The involvement of sphingosine kinase 1 in LPS-induced Toll-like receptor 4-mediated accumulation of HIF-1α protein, activation of ASK1 and production of the pro-inflammatory cytokine IL-6

Toll-like receptors (TLRs) lie in the core of resistance to infectious diseases allowing host immune cells to specifically detect pathogens by recognising their specific molecular patterns. Cell membrane-associated TLR4 (recognises lipopolysaccharide (LPS) of Gram-negative bacteria) and endosomal TLR7/8 (recognise viral single-stranded RNA) are known to activate hypoxia inducible factor-1α (HIF-1α) protein (necessary for cellular adaptation to the inflammatory stress) via redox-dependent mechanism. TLR4 triggers the cross talk between HIF-1α and apoptosis signal-regulating kinase 1 (ASK1), whereas TLR7/8 activates HIF-1α in the ASK1-independent manner. Here, we report that in THP-1 and RAW264.7 macrophages, ligand-induced activation of the TLR4 but not TLR7/8 induces activation and transcriptional upregulation of sphingosine kinase 1 (SphK1) in extracellular signal-regulating kinase and phospholipase C-1γ/PI3 kinase-dependent manner. TLR4-mediated SphK1 activation was found to be critical for the redox-dependent activation of HIF-1α and ASK1, as well as for the prevention of LPS-induced activation of caspase 3 and the expression of pro-inflammatory cytokine interleukin-6.

Antioxidant and antimutagenic effect of quercetin against DEN induced hepatotoxicity in rat

Diethylnitrosamine (DEN), a potent hepatocarcinogen, is found in tobacco smoke, processed meat as well as in different food products. Quercetin (QC), a naturally occurring flavonoid has excellent antioxidant properties. The present study was aimed to investigate the chemoprotective potential of QC against DEN induced hepatotoxicity in Sprague-Dawley (SD) rats. Quercetin was administered (10, 30 and 100 mg/kg) for 5 consecutive days after DEN (200 mg/kg) treatment. The animals were killed 24 h after the last dose of QC/saline treatment. The DEN induced hepatotoxicity was evident by elevated malondialdehyde (MDA) and decreased glutathione (GSH) levels in the liver. A significant increase in the levels of plasma aspartate transaminase (AST) and plasma alanine transaminase (ALT) was observed in the DEN treated group. The DEN induced DNA damage was evaluated using a single cell gel electrophoresis (SCGE) assay. A significant increase in the number of TUNEL positive cells was observed in the DEN treated group. Quercetin restored AST, ALT and GSH levels at all the tested doses. Restoration of the MDA level and cellular morphology was observed at doses of 10 and 30 mg/kg of QC. Further, DEN induced DNA damage and apoptosis was ameliorated by QC. The results indicate that QC ameliorates the DEN induced hepatotoxicity in rats and can be a candidate for a good chemoprotectant.

Involvement of hypoxia-inducible factor-1 HiF(1alpha) in IgE-mediated primary human basophil responses

Basophils play a pivotal role in regulating chronic allergic inflammation as well as angiogenesis. Here, we show for the first time that IgE-mediated activation of primary human basophils results in protein accumulation of the alpha-subunit of hypoxia-inducible factor 1alpha (HIF-1alpha), which is differentially regulated compared with signals controlling histamine release. HIF-1 facilitates cellular adaptation to hypoxic conditions such as inflammation and tumour growth by controlling glycolysis, angiogenesis and cell adhesion. ERK and p38 MAPK, but not reactive oxygen species (ROS), ASK1 or PI 3-kinase, were critical for IgE-mediated accumulation of HIF-1alpha, although the latter crucially affected degranulation. Abrogating HIF-1alpha expression in basophils using siRNA demonstrated that this protein is essential for vascular endothelial growth factor (VEGF) mRNA expression and, consequently, release of VEGF protein. In addition, HIF-1alpha protein alters IgE-induced ATP depletion in basophils, thus also supporting the production of the pro-allergic cytokine IL-4.

The involvement of hypoxia-inducible factor 1 alpha in Toll-like receptor 7/8-mediated inflammatory response

Toll-like receptors (TLRs) 7 and 8 are crucial in host defence against single-stranded RNA (ssRNA) viruses. Such viruses cause severe illnesses, which remain a serious medical burden in both industrialised and developing countries. TLR7/8 downstream signaling leads to a dramatic cellular stress associated with energy consumption. However, the molecular mechanisms of cell survival and adaptation to TLR7/8-induced stress, which give the cells an opportunity to initiate proper inflammatory reactions, are not clear at all. Here we report for the first time that ligand-induced activation of TLR7/8 leads to the accumulation of hypoxia-inducible factor 1 alpha (HIF-1alpha) protein in THP-1 human myeloid macrophages via redox- and reactive nitrogen species-dependent mechanisms. MAP kinases and phosphoinositol-3K are not involved in TLR7/8-mediated HIF-1alpha accumulation. Experiments with HIF-1alpha knockdown THP-1 cells have clearly demonstrated that HIF-1alpha is important for the protection of these cells against TLR7/8-induced depletion of ATP. Thus, HIF-1alpha might support both cell survival and the production of pro-inflammatory cytokines upon TLR7/8 activation.

Protection of mouse bone marrow from etoposide-induced genomic damage by dexrazoxane

PURPOSE

The objective of the current investigation is to determine whether non-toxic doses of the catalytic topoisomerase-II inhibitor, dexrazoxane, have influence on the genomic damage induced by the anticancer topoisomerase-II poison, etoposide, on mice bone marrow cells.

METHOD

The scoring of micronuclei, chromosomal aberrations, and mitotic activity were undertaken as markers of cyto- and genotoxicity. Oxidative damage markers such as reduced glutathione and lipid peroxidation were assessed as a possible mechanism underlying this amelioration.

RESULTS

Dexrazoxane pre-treatment significantly reduced the etoposide-induced micronuclei formation, chromosomal aberrations, and also the suppression of erythroblast proliferation in bone marrow cells of mice. These effects were dose dependent. Etoposide induced marked biochemical alterations characteristic of oxidative stress including enhanced lipid peroxidation and reduction in the reduced glutathione level. Prior administration of dexrazoxane ahead of etoposide challenge ameliorated these biochemical markers.

CONCLUSION

Based on our data presented, strategies can be developed to decrease the etoposide-induced genomic damage in normal cells using dexrazoxane.

The effects of quercetin on antioxidant status and tumor markers in the lung and serum of mice treated with benzo(a)pyrene

Chemoprevention has emerged as a very effective preventive measure against carcinogenesis. Several bioactive compounds present in fruits and vegetables have revealed their cancer curative potential on benzo(a)pyrene (B(a)P) induced carcinogenesis. In the present study, the efficacy of quercetin on the level of lipid peroxides, activities of antioxidant enzymes and tumor marker enzymes in B(a)P induced experimental lung carcinogenesis in Swiss albino mice was assessed. In lung cancer bearing animals there was an increase in lung weight, lipid peroxidation and marker enzymes such as aryl hydrocarbon hydroxylase, gamma glutamyl transpeptidase, 5'-nucleotidase, lactate dehydrogenase and adenosine deaminase with subsequent decrease in body weight and antioxidant enzymes-superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase, glutathione reductase, reduced glutathione, vitamin E and vitamin C. Quercetin supplementation (25 mg/kg body weight) attenuated all these alterations, which indicates the anticancer effect that was further confirmed by histopathological analysis. Overall, the above data shows that the anticancer effect of quercetin is more pronounced when used as an chemopreventive agent rather than as a chemotherapeutic agent against B(a)P induced lung carcinogenesis.

Effect of quercetin on oxidative nuclear and mitochondrial DNA damage

Quercetin is a well-investigated antioxidant known to protect cells against oxidative nuclear DNA damage. There is no knowledge regarding its effect on oxidative mitochondrial DNA damage. In this study we investigated the effect of quercetin on oxidatively-injured DNA. Cell-free and cell studies were performed. Cell-free analyses carried out on plasmidic DNA showed that quercetin protects from all oxidative challenges used. Cellular studies were carried out on NCTC 2544 cells which were insulted with hydrogen peroxide and UVC radiations. Nuclear and mitochondrial DNAs were analysed by measuring DNA damage with a quantitative polymerase chain reaction. Quercetin supplementation showed significant genoprotective activity on mitochondrial DNA when hydroperoxide was used. The evidence of the protection afforded by quercetin suggests that this flavonoid may play an important role on mitochondrial genome stability.