Transcript profiles of mitochondrial and cytoplasmic manganese superoxide dismutases in Exopalaemon carinicauda under ammonia stress

Superoxide dismutase （SOD） is one of the most important antioxidant defense enzymes, and is considered as the first line against oxidative stress. In this study, we cloned a mitochondrial manganese （Mn） SOD （mMnSOD） cDNA from the ridgetail white prawn Exopalaemon carinicauda by using rapid amplification of cDNA ends （RACE） methods. The fulMength cDNA for mMnSOD was 1 014-bp long, containing a 5＇-untranslated region （UTR） of 37-bp, a 3＇-UTR of 321-bp with a poly （A） tail, and included a 657-bp open reading frame encoding a protein of 218 amino acids with a 16-amino-acid signal peptide. The protein had a calculated molecular weight of 23.87 kDa and a theoretical isoelectric point of 6.75. The mMnSOD sequence included two putative N-glycosylation sites （NHT and NLS）, the MnSOD signature sequence 18~DVWEHAYY^87, and four putative Mn binding sites （H48, H96, D180, and H184）. Sequence comparison showed that the mMnSOD deduced amino acid sequence of E. carinicauda shared 97%, 95%, 89%, 84%, 82%, 72%, and 69% identity with that ofMacrobrachium rosenbergii, Macrobrachium nipponense, Fenneropeneaus chinensis, Callinectes sapidus, Perisesarma bidens, Danio rerio, and Homo sapiens, resectively. Quantitative real-time RT-PCR analysis showed that mMnSOD transcripts were present in all E. carinicauda tissues examined, with the highest levels in the hepatopancreas. During an ammonia stress treatment, the transcript levels of mMnSOD and cMnSOD were up-regulated at 12 h in hemocytes and at 24 h in the hepatopancreas. As the duration of the ammonia stress treatment extended to 72 h, the transcript levels of mMnSOD and cMnSOD significantly decreased both in hemocytes and hepatopancreas. These findings indicate that the SOD system is induced to respond to acute ammonia stress, and may be involved in environmental stress responses in E. carinicauda.

Serum manganese superoxide dismutase and thioredoxin are potential prognostic markers for hepatitis C virus-related hepatocellular carcinoma

AIM:To evaluate the clinical significance of oxidative stress markers in patients with hepatitis C virus(HCV)related hepatocellular carcinoma(HCC).METHODS:Sixty-four consecutive patients who were admitted to Kagoshima University Medical and Dental Hospital were enrolled in this retrospective study.All patients had chronic liver disease(CLD) due to infection with HCV.Thirty patients with HCV-related HCC,34 with HCV-related CLD without HCC(non-HCC),and 20 healthy volunteers(HVs) were enrolled.Possible associations between serum manganese superoxide dismutase(MnSOD) and thioredoxin(TRX) levels and clinical parameters or patient prognosis were analyzed over a mean follow-up period of 31.7 mo.RESULTS:The serum MnSOD levels were significantly higher in patients with HCV-related HCC than in patients without HCC(P = 0.03) or HVs(P < 0.001).Similarly,serum TRX levels were also significantly higher in patients with HCV-related HCC than in patients without HCC(P = 0.04) or HVs(P < 0.01).However,serum levels of MnSOD and TRX were not correlated in patients with HCC.Among patients with HCC,the overall survival rate(OSR) was lower in patients with MnSOD levels ≥ 110 ng/mL than in patients with levels < 110 ng/mL(P = 0.01),and the OSR tended to be lower in patients with TRX levels < 80 ng/mL(P = 0.05).In addition,patient prognosis with HCC was poorest with serum MnSOD levels ≥ 110 ng/mL and serum TRX levels < 80 ng/mL.Furthermore,a multivariate analysis using a Cox proportional hazard model and serum levels of five factors(MnSOD,prothrombin time,serum albumin,serum α-fetoprotein(AFP),and serum des-γ-carboxy prothrombin) revealed that MnSOD levels ≥ 110 ng/mL(risk ratio:4.12,95% confidential interval:1.22-13.88,P = 0.02) and AFP levels ≥ 40 ng/mL(risk ratio:6.75;95% confidential interval:1.70-26.85,P < 0.01) were independent risk factors associated with a poor patient prognosis.CONCLUSION:Serum MnSOD and TRX levels are potential clinical biomarkers that predict patient prognosis in HCV-related HCC.

Differential Regulation of Proteins and a Possible Role for Manganese Superoxide Dismutase in Bioluminescence of Panellus stipticus Revealed by Suppression Subtractive Hybridization

Suppression subtractive hybridization (SSH) was employed to investigate bioluminescence in Panellus stipticus (Bull.) P. Karst. by detecting proteins differentially expressed in bioluminescent and luminescent strains. Comparisons of luminescent and non-luminescent monokaryon cultures of North American strains revealed differences in transcript levels of proteins responsible for post-translational modification (PTM) of enzymes. A similar comparison of a luminescent strain of P. stipticus from North America with a non-luminescent European strain revealed the presence of extracellular manganese superoxide dismutase (MnSOD) in the luminescent form, in addition to proteins involved in PTM. The application of MnSOD-specific inhibitors to luminescent mycelium resulted in the rapid loss of luminescence. The relevance to luminescence of proteins involved in PTM is discussed, together with a possible role for MnSOD that considers the potential for SODs to form stable complexes with catechols revealed in previously published research. In light of the recent discovery that hispidine may be the precursor of fungal luciferin, we consider a hypothetical mechanism for fungal luminescence in which the ο-hydroquinone moiety of a hispidine derivative ligates with the extracellular form of MnSOD producing a semiquinone-radical complex, with the resultant semiquinonato complex potentially reacting with molecular oxygen or other reactive oxygen species to produce sufficiently excited intermediates to emit light on relaxation.

Up-regulated manganese superoxide dismutase expression increases apoptosis resistance in human esophageal squamous cell carcinomas

Background Esophageal cancer is one of the most common malignancies in the world. In order to identify the proteins associated with esophageal squamous cell carcinomas （ESCC）, we analyzed the protein profiles of ESCC cases with tumor and matched adjacent normal tissues. Methods Two-dimensional electrophoresis （2-DE） was carried out to analyze the protein profiles. Dysregulated protein spots were identified by Matrix-Assisted Laser Desorption Ionization Time-of-Flight （MALDI-TOF） and verified by liquid chromatography/electrospray ionization ion trap-mass spectrometry/mass spectrometry （LC-ESI-IT MS）. RT-PCR and immunohistochemistry on tissue microarray were performed to confirm the gene dysregulation in esophageal cancerous tissues. RNA interference （RNAi） was used to knock down the gene expression in ESCC cell lines. Apoptosis assay with annexin V-FITC/PI staining was conducted and cells were analyzed by flow cytometry. Results 2-DE showed that two protein spots with approximate molecular weights and different pl were elevated in 12 out of 18 ESCCs as compared to the corresponding normal tissues. Both the two spots were identified as MnSOD by MALDI-TOF and were verified by LC-ESI-IT MS. MnSOD overexpression was detected in 14 tumors out of 24 cases by RT-PCR and 52 tumors out of 116 cases by immunohistochemistry comparing to normal epithelia, siRNA-mediated silencing of MnSOD in KYSE450 and KYSE150 cell lines revealed that MnSOD protected ESCC cells from apoptosis induced by ultraviolet （UV） and doxorubicin （DOX）. Conclusions These findings suggest that there existed two isoforms of MnSOD protein in normal and tumor esophageal tissues. MnSOD was overexpressed in ESCC and its up-regulation in esophageal cancer cells was associated with apoptosis resistance.

Mn-SOD and CuZn-SOD polymorphisms and interactions with risk factors in gastric cancer

AIM: To investigate the effects of superoxide dismutase (SOD) polymorphisms (rs4998557 , rs4880), Helicobacter pylori (H. pylori ) infection and environmental factors in gastric cancer (GC) and malignant potential of gastric precancerous lesions (GPL). METHODS: Copper-zinc superoxide dismutase (SOD1, CuZn-SOD)-G7958A (rs4998557 ) and manganese superoxide dismutase (SOD2, Mn-SOD)-Val16Ala (rs4880 ) polymorphisms were genotyped by SNaPshot multiplex polymerase chain reaction (PCR) in 145 patients with GPL (87 cases of gastric ulcer, 33 cases of gastric polyps and 25 cases of atrophic gastritis), 140 patients with GC and 147 healthy controls. H. pylori infection was detected by immunoblotting analysis. RESULTS: The SOD1-7958A allele was associated with a higher risk of gastric cancer [odds ratio (OR) = 3.01, 95% confidence intervals (95% CI): 1.83-4.95]. SOD216Ala/Val genotype was a risk factor for malignant potential of GPL (OR = 2.04, 95% CI: 1.19-3.49). SOD216Ala/genotype increased the risk of gastric cancer (OR = 2.85, 95% CI: 1.66-4.89). SOD1-7958A/genotype, SOD2-16Ala/genotype, alcohol drinking, positive family history and type Ⅰ H. pylori infection were associated with risk of gastric cancer, and there were additive interactions between the two genotypes and the other three risk factors. SOD2-16Ala/Val genotype and positive family history were associated with malignant potential of GPL and jointly contributed to a higher risk for malignant potential of GPL (OR = 7.71, 95% CI: 2.10-28.22). SOD1-7958A/genotype and SOD2-16Ala/genotype jointly contributed to a higher risk for gastric cancer (OR = 6.43, 95% CI: 3.20-12.91). CONCLUSION: SOD1-7958A/and SOD2-16Ala/-genotypes increase the risk of gastric cancer in Chinese Han population. SOD2-16Ala/-genotype is associated with malignant potential of GPL.

Mitochondrial DNA4977-bp deletion correlated with reactive oxygen species production and manganese superoxide dismutase expression in gastric tumor cells

Background Mitochondrial DNA 4977-bp deletion （△mtDNA^4977） was reported in many human neoplasia. However, its biological significance remains to be evaluated and the molecular mechanism needs to be investigated. In this study, we analyzed the frequency of △mtDNA^4977 in gastric cancer （GC） cell lines and tissues, as well as reactive oxygen species （ROS） contents and manganese superoxide dismutase （MnSOD） expression levels in GC cell lines to explore its biological significance and molecular mechanism. Methods Semi-quantitative PCR and real-time PCR were used to detect the incidence of △mtDNA^4977 in 13 GC cell lines and 272 human gastric tissues （108 GC specimens and the respective adjacent normal tissues, and 56 normal gastric mucosa from non-cancer patients）. We further identified intracellular ROS production by flow cytometry and MnSOD expression by semi-quantitative reverse transcription-PCR （RT-PCR） and Western blotting. Statistical analyses were carried out using the Logistic regression analysis and Kaplan-Meier method. Results Based on our earlier study, we optimized the PCR amplification condition by reducing the cycle number. In this study, we systematically documented the high incidence of △mtDNA^4977 in GC cell lines （10/13, 76.9%）, GC tissues （86/108, 79.6%）, matched normal tissues （73/108, 67.6%）, and normal gastric mucosa of non-cancer patients （29/56, 51.8%）. A significantly higher incidence of mutated △mtDNA^4977 was observed in GC tissues with respect to the adjacent normal tissues （79.6% vs 67.6%, P=-0.045）, and they were both higher than that in normal controls （P 〈0.05）. Most importantly, we linked the △mtDNA^4977 mutations with the expression level of MnSOD and ROS contents. The cell lines containing lower expression level of MnSOD was found to have generally higher frequent △mtDNA^4977 and more ROS. Conclusion The decreased anti-oxidative ability, which leads to increased ROS contents, is correlated with the mtDNA damage during gastric carcinogenesis.

The Expression of Manganese Superoxide Dismutase Gene from Nelumbo nucifera Responds Strongly to Chilling and Oxidative Stresses

A manganese superoxide dismutase （Mn-SOD） gene, NnMSD1, was identified from embryonic axes of the sacred lotus （Nelumbo nucifera Gaertn.）. The NnMSD1 protein contains all conserved residues of the Mn-SOD protein family, including four consensus metal binding domains and a signal peptide for mitochondrial targeting. Southern blot analysis suggests the existence of two Mn.SOD genes in sacred lotus. NnMSD1 was highly expressed in developing embryonic axes during seed development, but appeared in cotyledons only at the early stage of development and became undetectable in the cotyledons during late embryogenesis. The expression of the NnMSD1 gene in germinating embryonic axes, in response to various stresses such as heat shock, chilling, and exposure to stress-related chemicals, was also studied. Heat shock strongly inhibited the expression of the NnMSD1 gene, whereas the NnMSD1 transcript level increased strongly in chilling stress treatment. An increase in expression was also highly induced by H2O2 in germinating embryonic axes. The results suggest that the expression pattern of the NnMSD1 gene differed between developing axes and cotyledons, and that the NnMSD1 gene expression responds strongly to chilling and oxidative stress.

Activation of AMPK/MnSOD signaling mediates anti-apoptotic effect of hepatitis B virus in hepatoma cells

AIM: To investigate the anti-apoptotic capability of the hepatitis B virus(HBV) in the HepG2 hepatoma cell line and the underlying mechanisms.METHODS: Cell viability and apoptosis were measured by MTT assay and flow cytometry, respectively. Targeted knockdown of manganese superoxide dismutase(Mn SOD), AMP-activated protein kinase(AMPK) and hepatitis B virus X protein(HBx) genes as well as AMPK agonist AICAR and antagonist compound C were employed to determine the correlations of expression of these genes.RESULTS: HBV markedly protected the hepatoma cells from growth suppression and cell death in the condition of serum deprivation. A decrease of superoxide anion production accompanied with an increase of Mn SOD expression and activity was found in Hep G2.215 cells. Moreover, AMPK activation contributed to the up-regulation of Mn SOD. HBx protein was identified to induce the expression of AMPK and Mn SOD. CONCLUSION: Our results suggest that HBV suppresses mitochondrial superoxide level and exerts an antiapoptotic effect by activating AMPK/Mn SOD signaling pathway, which may provide a novel pharmacological strategy to prevent HCC.

NADPH Oxidase Accounts for Changes in Cerebrovascular Redox Status in Hindlimb Unweighting Rats

Objective The roles of cerebrovascular oxidative stress in vascular functional remodeling have been described in hindlimb-unweighting （HU） rats. However, the underlying mechanism remains to be established. Methods We investigated the generation of vascular reactive oxygen species （ROS）, Nox2/Nox4 protein and mRNA levels, NADPH oxidase activity, and manganese superoxide dismutase （MnSOD） and glutathione peroxidase-1 （GPx-1） mRNA levels in cerebral and mesenteric smooth muscle cells （VSMCs） of HU rats. Results ROS production increased in cerebral but not in mesenteric VSMCs of HU rats compared with those in control rats. Nox2 and Nox4 protein and mRNA levels were increased significantly but MnSOD/GPx-1 mRNA levels decreased in HU rat cerebral arteries but not in mesenteric arteries. NADPH oxidases were activated significantly more in cerebral but not in mesenteric arteries of HU rats. NADPH oxidase inhibition with apocynin attenuated cerebrovascular ROS production and partially restored Nox2/Nox4 protein and mRNA levels, NADPH oxidase activity, and MnSOD/GPx-1 mRNA levels in cerebral VSMCs of HU rats. Conclusion These results suggest that vascular NADPH oxidases regulate cerebrovascular redox status and participate in vascular oxidative stress injury during simulated microgravity.

Effect of Nitric Oxide on Esophageal Cancer Cell Line TE-1

Objective To investigate the radiosensitizing effect of nitric oxide(NO) combined with radiation on esophageal cancer cell line TE-1.Methods Methyl thiazolyl tetrazolium(MTT) assay was used to assess the effects of NO and radiation on TE-1 cells regarding inhibition of cell proliferation.Flow cytometry was used to examine the effect of NO and radiation on cell apoptosis and cycle.Reverse transcription polymerase chine reaction and Western blot were used to evaluete the effect of NO on mRNA and protein expression of manganese superoxide dismutase(MnSOD).Results NO inhibited the proliferation of TE-1 cells while significantly enhancing their radiosensitivity.The application of NO combined with radiation significantly increased the apoptosis rate and G2/M phase proportion of TE-1 cells,with substantial decreases in the MnSOD mRNA and protein expression levels.Conclusions NO reduces the MnSOD mRNA and protein expression levels by affecting TE-1 cell cycle,further inhibiting the apoptosis of esophageal cancer cells and enhancing the killing effect of radiation on esophageal cancer cells.

Study on effect of BSO on esophageal cancer cell line TE-1

Objective: The aim of the study was to investigate the sensitizing effect of buthionine sulfoximine (BSO) and radiation on esophageal cancer cell line TE-1. Methods: Methyl thiazolyl tetrazolium (MTT) assay was used to observe the inhibition of BSO and radiation on cell proliferation, and to investigate the sensitizing effect of BSO on esophageal cancer cell line TE-1. Flow cytometry (FCM) was used to observe the effect of BSO and radiation on cell apoptosis and cycle. Reverse transcription polymerase chain reaction (RT-PCR) and Western blot were used to observe the effect of BSO on manganese superoxide dismutase (MnSOD) mRNA and protein expression. Results: BSO could inhibit the proliferation of TE-1 esophageal cancer cells, and had significant dose- and time-dependent radiosensitizing effects on TE-1 esophageal cancer cells. After the combined effects of BSO and radiation on TE-1 cells, the rate of apoptosis and G2/M phase proportion increased significantly, and MnSOD mRNA and protein expression decreased. Conclusion: BSO may reduce MnSOD mRNA and protein expression by affecting TE-1 cell cycle, thus inhibiting and inducing the apoptosis of esophageal cancer cells and enhancing the killing effect of the radiation on esophageal cancer cells.

Predictive biomarker and clinicopathological characteristics analysis for esophageal cancer

Objective:The aim of this study was to explore the expression of manganese superoxide dismutase(MnSOD) in esophageal squamous cell carcinoma and its relationship with clinicopathological characteristics and its biological behavior.Methods:Immunohistochemical method(SP method),reverse transcription-polymerase chain reaction(RT-PCR) and Western blot were combined to detect the MnSOD protein and mRNA expression in 45 cases of esophageal squamous cell carcinoma and the normal tissue that was 5 cm apart from the edge of esophageal cancer lesion and without documented microscopic invasive cancer.Meanwhile,analysis was performed on the relationship between the pathological features of esophageal cancer and its biological behavior.Results:In esophageal squamous cell carcinoma and normal esophageal tissue,MnSOD protein expression was identified in 31.1%(14/45) and 86.7%(31/45)(P = 0.003),respectively,with the relative expression levels of MnSOD mRNA were 0.310 ± 0.036 and 0.482 ± 0.053(P = 0.000).The longer the lesions and the deeper the invasion,the differentiation would become poorer and the expression level of MnSOD would get lower,indicating that the level of MnSOD protein and mRNA expression were closely related to esophageal squamous cell carcinoma in the length of lesion,depth of invasion,and degree of differentiation(P < 0.05).Nevertheless,it showed no association with the presence of the lymph node metastasis,lesion site and the macroscopic classification(P > 0.05).Conclusion:The MnSOD protein and mRNA expression were both decreased in esophageal squamous cell carcinoma tissue.This may be related to the carcinogenesis and development of esophageal cancer.Detection of the expression of MnSOD would be of clinical significance in understanding the prognosis and guiding therapeutic strategy of esophageal cancer.