Effects of quercetin on hyper-proliferation of gastric mucosal cells in rats treated with chronic oral ethanol through the reactive oxygen species-nitric oxide pathway

AIM： To investigate the effect of quercetin （3,3,4,5, 7-pentahydroxy flavone）, a major flavonoid in human diet, on hyper-proliferation of gastric mucosal cells in rats treated with chronic oral ethanol. METHODS： Forty male Sprague-Dawley rats, weighing 200-250 g, were randomly divided into control group （tap wateradlibitum）, ethanol treatment group （6 mL/L ethanol）, quercetin treatment group （intragastric gavage with 100 mg/kg of quercetin per day）, and ethanol plus quercetin treatment group （quercetin and 6 mL/L ethanol）. Expression levels of proliferating cell nuclear antigen （PCNA）and Cyclin D1 were detected by Western blot to assay gastric mucosal cell proliferation in rats. To demonstrate the influence of quercetin on the production of extra-cellular reactive oxygen species/ nitrogen species （ROS/RNS） in rats, changes in levels of thiobarbituric acid reactive substance （TBARS）, protein carbonyl, nitrite and nitrate （NOx） and nitrotyrosine （NT） were determined. The activity of inducible nitric oxide synthase （NOS） including iNOS and nNOS was also detected by Western blot.RESULTS：Compared to control animals, cell proliferation in the gastric mucosa of animals subjected to ethanol treatment for 7 days was significant increased （increased to 290% for PCNA density P 〈 0.05, increased to 150 for Cyclin D1 density P 〈 0.05 and 21.6 ± 0.8 vs 42.3 ± 0.7 for PCNA positive cells per view field）, accompanied by an increase in ROS generation （1.298 ± 0.135 μmol vs 1.772 ± 0.078 μmol for TBARS P 〈 0.05; 4.36 ± 0.39 μmol vs 7.48 ± 0.40 μmol for carbonyl contents P 〈 0.05） and decrease in NO generation （11.334 ± 0.467 μmol vs 7.978 ± 0.334 μmol P 〈 0.01 for NOx; 8.986 ± 1.351 μmol vs 6.854 ± 0.460 μmol for nitrotyrosine P 〈 0.01） and nNOS activity （decreased to 43% P 〈 0.05）. This function was abolished by the co-administration of quercetin. CONCLUSION： The antioxidant action of quercetin relies, in part, on its ability to stimulate nNOS and enhance production of NO that would interact with endogenously produced reactive oxygen to inhibit hyper-proliferation of gastric mucosal cells in rats treated with chronic oral ethanol.

Alcohol-induced steatosis in liver cells

Alcohol-induced fatty liver (steatosis) was believed to result from excessive generation of reducing equivalents from ethanol metabolism, thereby enhancing fat accumulation. Recent findings have revealed a more complex picture in which ethanol oxidation is still required, but specific transcription as well as humoral factors also have important roles. Transcription factors involved include the sterol regulatory element binding protein 1 (SREBP-1) which is activated to induce genes that regulate lipid biosynthesis. Conversely, ethanol consumption causes a general down-regulation of lipid (fatty acid) oxidation, a reflection of inactivation of the peroxisome proliferator- activated receptor-alpha (PPAR-α) that regulates genes involved in fatty acid oxidation. A third transcription factor is the early growth response-1 (Egr-1), which is strongly induced prior to the onset of steatosis. The activities of all these factors are governed by that of the principal regulatory enzyme, AMP kinase. Important humoral factors, including adiponectin, and tumor necrosis factor-α (TNF-α), also regulate alcohol-induced steatosis. Their levels are affected by alcohol consumption and by each other. This review will summarize the actions of these proteins in ethanol-elicited fatty liver. Because steatosis is now regarded as a significant risk factor for advanced liver pathology, an understanding of the molecular mechanisms in its etiology is essential for development of effective therapies.

Alcoholic liver disease and hepatitis C:A frequently underestimated combination

Alcoholic liver disease(ALD) and hepatitis C virus(HCV) infection represent, either alone or in combination, more than two thirds of all patients with liver disease in the Western world.This review discusses the epidemiology and combined impact of ALD and HCV on the progres sion of liver disease.ALD and HCV affect the progres sion of liver disease to liver cirrhosis and hepatocellular carcinoma(HCC) in a synergistic manner.Thus, the risk for HCC increases f ive times with a daily alcohol con sumption of 80 g;in the presence of HCV it is increased 20fold, and a combination of both risk factors leads to a more than 100fold risk for HCC development.Alcohol consumption also decreases the response to interferon treatment which is probably due to a lack of compliance than a direct effect on HCV replication.Several molecu lar mechanisms are discussed that could explain the synergistic interaction of alcohol and HCV on disease progression.They include modulation of the immune response and apoptosis, increased oxidative stress via induction of CYP2E1 and the hepatic accumulation of iron.Thus, both HCV and alcohol independently cause hepatic iron accumulation in > 50% of patients probably due to suppression of the liversecreted systemic iron hormone hepcidin.A better understanding of hepcidin regulation could help in developing novel therapeutic approaches to treat the chronic disease in the future.For now, it can be generally concluded that HCVinfect ed patients should abstain from alcohol and alcoholicsshould be encouraged to participate in detoxification programs.

Control of oxidative stress in hepatocellular carcinoma: Helpful or harmful?

Oxidative stress is becoming recognized as a key factor in the progression of chronic liver disease(CLD) and hepatocarcinogenesis. The metabolically important liver is a major reservoir of mitochondria that serve as sources of reactive oxygen species, which are apparently responsible for the initiation of necroinflammation. As a result, CLD could be a major inducer of oxidative stress. Chronic hepatitis C is a powerful generator of oxidative stress, causing a high rate of hepatocarcinogenesis among patients with cirrhosis. Non-alcoholic steatohepatitis is also associated with oxidative stress although its hepatocarcinogenic potential is lower than that of chronic hepatitis C. Analyses of serum markers and histological findings have shown that hepatocellular carcinoma correlates with oxidative stress and experimental data indicate that oxidative stress increases the likelihood of developing hepatocarcinogenesis. However, the results of antioxidant therapy have not been favorable. Physiological oxidative stress is a necessary biological response, and thus adequate control of oxidative stress and a balance between oxidative and anti-oxidative responses is important. Several agents including metformin and L-carnitine can reportedly control mechanistic oxidative stress. This study reviews the importance of oxidative stress in hepatocarcinogenesis and of control strategies for the optimal survival of patients with CLD and hepatocellular carcinoma.

Upconversion nano-photosensitizer targeting into mitochondria for cancer apoptosis induction and cyt c fluorescence monitoring

Disruption of mitochondrial reactive oxygen species （mitoROS） plays a major role in cancer cell apoptosis. Here, we designed a core/shell-structured mitochondriatargeting upconversion-based nano-photosensitizer （TPP-UC（PS）） with a lanthanidedoped upconversion nanoparticle （UCNP） core coated by a photosensitizer （PS）-incorporated dense silica shell. Following irradiation with external nearinfrared laser （NIR）, TPP-UC（PS） in mitochondria caused serious mitochondrial matrix swelling for the activated upconversion-based photodynamic therapy （UC-PDT）, and the mobilization of cytochrome c （cyt c） was amplified in response to the increased mitoROS. Specifically, this heme-containing cyt c could be monitored by varying TPP-UC（PS）＇s upconversion luminescence signal （UCL）, which may facilitate the in situ detection of cyt c for apoptosis research. As a proof of concept, our designed TPP-UC（PS） may provide significant opportunities for controlling cancer cell apoptosis under NIR stimulation and for studying apoptosis using the dynamic UCL, which is influenced by local cyt c.

Phyto-Toxicity of Chromium in Maize： Oxidative Damage, Osmolyte Accumulation, Anti-Oxidative Defense and Chromium Uptake

Agricultural production systems are immensely exposed to different environmental stresses in which heavy metal stress receives serious concerns. This study was conducted to explore the deleterious effects of different chromium （Cr） stress levels, i.e., O, 30, 60, 90, 120, and 150 μmol L^-1, on two maize genotypes, Wandan 13 and Runnong 35. Both genotypes were evaluated by measuring their growth and yield characteristics, Cr accumulation in different plant tissues, alterations in osmolyte accumulation, generation of reactive oxygen species （ROS）, and anti-oxidative enzyme activity to scavenge ROS. The results showed that Cr stress decreased the leaf area, cob formation, 100-grain weight, shoot fresh biomass, and yield formation, while Cr accumulation in different maize tissues was found in the order of roots 〉 leaves 〉 stem ~ seeds in both genotypes. The increased Cr toxicity resulted in higher free proline, soluble sugars and total phenolic contents, and lower soluble protein contents. However, enhanced lipid peroxidation was noticed in the forms of malondialdehyde, hydrogen peroxide （H2O2） and thiobarbituric acid reactive substance accumulation, and electrolyte leakage. The hyperactivity of superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, especially glutathione peroxidase and glutathione reductase indicated that these anti-oxidative enzymes had a central role in protecting maize from Cr toxicity, especially for Wandan 13. Moreover, higher uptake and less translocation of Cr contents into the grains of Wandan 13 implied its importance as a potential candidate against soil Cr pollution.

Killing of Staphylococcus aureus by allylpyrocatechol is potentiated by induction of intracellular oxidative stress and inhibition of catalase activity

OBJECTIVE： This study investigated the effects of allylpyrocatechol （APC）, the major component in ethanolic extract of Piper betle, on key oxidative stress resistance enzymes important for the survival of Staphylococcus aureus, a major pathogen in the human host. METHODS： Effects of APC on expressions of genes encoding catalase （katA）, superoxide dismutases （SODs）, including soda and sodM, and alkyl hydroperoxide reductase （ahpC） in S. aureus were quantitated by RT-qPCR in reference to gyrA and 16S rRNA. Corresponding activities of the enzymes were also investigated. The Livak analysis was performed for verification of gene-fold expression data. Effects of APC on intracellular and extracellular reactive oxygen species （ROS） levels were determined using the nitroblue tetrazolium （NBT） reduction assay. RESULTS： APC-treated S. aureus cells had higher sodA and sodM transcripts at 1.5-fold and 0.7-fold expressions respectively with corresponding increase in total SOD activity of 12.24 U/mL compared to untreated cells, 10.85 U/mL （P〈0.05）. Expression of ahpC was highest in APC-treated cells with 5.5-fold increased expression compared to untreated cells （P〈0.05）. Correspondingly, ahpC activity was higher in APC-treated cells at 0.672 （A310nm） compared to untreated cells which was 0.394 （A310nm）. In contrast, katA expression was 1.48-fold and 0.33-fold lower respectively relative to gyrA and 16S rRNA. Further, APC-treated cells showed decreased catalase activity of 1.8 × 10^-4 （U/L or μmol/（min.L）） compared to untreated cells, which was 4.8 × 10^-4 U/L （P〈0.05）. Absorbance readings （A575nm） for the NBT reduction assay were 0.709 and 0.695 respectively for untreated and treated cells, which indicated the presence of ROS. APC-treated S. aureus cells had lower ROS levels both extracellularly and intracellularly, but larger amounts remained intracellularly compared to extracellular levels with absorbances of 0.457 and 0.137 respectively （P〈0.05）. CONCLUSION： APC induced expressions of both sodA and sodM, resulting in increased total SOD activity in S. aureus. Higher sodA expression indicated stress induced intracellularly involving O2, presumably leading to higher intracellular pools of H2O2. A concommittant decrease in katA expression and catalase activity possibly induced ahpC expression, which was increased the highest in APC-treated cells. Our findings suggest that in the absence of catalase, cells are propelled to seek an alternatepathway involving ahpC to reduce stress invoked by O2- and H2O2. Although APC reduced levels of ROS, significant amounts eluded its antioxidative action and remained intracellularly, which adds to oxidative stress in treated cells.

Apoptosis of RKO Induced by Catechins and GA through Ca^(2+) and LIP

The anti-tumor effects of catechins and gallic acid （GA） in-vitro was investigated in this paper. Fluo-3AM, Calcium-AM （Ca-AM）, 2＇, 7＇ -dichlorofluorescein-diacetate（DCFH-DA）, 4＇ ,6-dia- midino-2- phenylindole （DAPI） and Ca-AM plus colbat were used to characterize intracellular calcium, labile iron pool （LIP）, reac- tive oxygen species （ROS）, nuclei morphology and mitochondrial permeability transition pore （mPTP） opening, respectively. High performance liquid chromatography （HPLC） was used to quanti- tare catechins and GA in the cultural medium. The results indi- cated that each of them showed dose response inhibition of cell growth, provoking nuclei condensation, intracellular calcium ele- vation, mPTP opening, LIP reduction, and cytochrome c （Cyt-C） to release into cytosol. The caspase inhibitors, 2-aminoethox- ydiphenol borate （APB） or Fe3＋ could inhibit lethal effects of GA and （-）-epigallocatechin （EGC）, but failed to affect （-）-epigalloca- techin gallate （EGCG） and （-）-epicatechin gallate （ECG）. Level of ROS presented negative growth while their concentration de- creased in the medium. In conclusion, our findings suggest that viability of RKO decreased because of their good correlation with elevation of calcium and loss of L1P and ROS in cytosol.