Alterations of the levels of primary antioxidant enzymes in different grades of human astrocytoma tissues

Malignant astrocytoma is the most commonly occurring brain tumour in humans. Oxidative stress is implicated in the development of cancers. Superoxide dismutase 2 (SOD2) was found to exert tumour suppressive effect in basic research, but increased SOD2 protein level was associated with higher aggressiveness of human astrocytomas. However, studies reporting alterations of antioxidant enzymes in human astrocytomas often employed less accurate methods or included different types of tumours. Here we analysed the mRNA levels, activities, and protein levels of primary antioxidant enzymes in control brain tissues and various grades of astrocytomas obtained from 40 patients. SOD1 expression, SOD1 activity, and SOD1 protein level were lower in Grade IV astrocytomas. SOD2 expression was lower in low-grade (Grades I and II) and Grade III astrocytomas than in controls, but SOD2 expression and SOD2 protein level were higher in Grade IV astrocytomas than in Grade III astrocytomas. Although there was no change in SOD2 activity and a lower activity of citrate synthase (CS), the MnSOD:CS ratio increased in Grade IV astrocytomas compared with controls and low-grade astrocytomas. Furthermore, SOD1 activity, CS activity, SOD1 expression, GPX4 expression, and GPX4 protein level were inversely correlated with the malignancy, whereas catalase activity, catalase protein, SOD2 protein level, and the SOD2:CS ratio were positively correlated with the degree of malignancy. Lower SOD2:CS ratio was associated with poor outcomes for Grade IV astrocytomas. This is the first study to quantify changes of various primary antioxidant enzymes in different grades of astrocytomas at different levels concurrently in human astrocytomas.     

Activity of redox-regulatory systems in the tumor and surrounding tissues in various histological types of tumors

According to modern concepts, a malignant tumor is a complex dynamic system possessing numerous links with both the immediate environment and remote non-malignant tissues and organs. Changes in their redox balance can result in disruption of the normal tissue control. The aim of our study was to compare activity of enzymes influencing the redox state in the tumor tissue, peritumoral area, and nonmalignant tissues (taken by resection line) at various histological tumor variants. We found similar close level of reduced glutathione in the tissues of gastric adenocarcinoma and vulvar squamous cell carcinoma; however, dynamics of this parameter in the tumor surrounding tissues was different. In contrast to gastric adenocarcinoma, vulvar squamous cell carcinoma was characterized by a significant increase in glutathione content in the tumor tissue and increased activity of all investigated enzymes of the glutathione system in the tumor tissue and its peritumoral area as compared with the surrounding non-malignant tissue. These results underlie existence of clear differences in the functioning of the redox regulatory systems in the tumor and surrounding tissues of various histological origin and localization; these differences may be possibly attributed to different mechanisms involved in maintenance of the redox balance in the originally non-malignant tissues.     

Role of Glutathione-Dependent Peroxidase in Regulation of Lipoperoxide Utilization in Malignant Tumors

Glutathione content, the activity of glutathione-dependent enzymes (glutathione reductase, glutathione peroxidase, and glutathione S-transferase), and also SOD (superoxide dismutase) and catalase were studied in human malignant tumors (uterus, breast, and ovaries) and normal tissues. Glutathione level and the activity of glutathione-dependent enzymes were 2-3 times higher in the malignant tumors than in normal tissues. A negative correlation between the level of glutathione and glutathione-dependent enzymes (glutathione peroxidase and glutathione S-transferase) in tumors and the efficacy of postoperative chemotherapy may characterize the degree of tumor resistance to chemotherapy and therefore may have prognostic value. Low SOD and catalase activity and high activity of glutathione-dependent enzymes in tumors suggest that glutathione peroxidase and glutathione S-transferase play a major role in peroxide utilization in malignant tumors.     

运动对人体自由基代谢的影响

自由基代谢普遍存在于机体各组织。正常情况下,人体自由基的产生与清除处于平衡状态。而人体自由基产生过多或机体清除自由基能力下降将给机体带来损伤。本文采用文献资料法,阐述了自由基的类型、功能、自由基产生的机制以及抗氧化系统的种类等基本理论。通过对力竭运动、耐力运动和无氧运动3种不同形式的运动对自由基代谢及抗氧化酶活性的研究得出结论:不同的运动形式及负荷方式对体内自由基代谢及抗氧化酶活性将产生不同影响;运动对自由基代谢影响具有器官与组织差异性。这些研究成果为科学指导运动训练和健身活动、快速有效的消除运动性疲劳并增强运动能力提供重要的科学理论依据。     

ASPM-associated stem cell proliferation is involved in malignant progression of gliomas and constitutes an attractive therapeutic target

Background

ASPM (Abnormal Spindle-like Microcephaly associated) over-expression was recently implicated in the development of malignant gliomas.

Results

To better characterize the involvement of ASPM in gliomas, we investigated the mRNA expression in 175 samples, including 8 WHO Grade II, 75 WHO Grade III and 92 WHO Grade IV tumors. Aspm expression was strongly correlated with tumor grade and increased at recurrence when compared to the initial lesion, whatever the initial grade of the primary tumor. ASPM expression also increased over serial passages in gliomaspheres in vitro and in mouse xenografts in vivo. Lentivirus-mediated shRNA silencing of ASPM resulted in dramatic proliferation arrest and cell death in two different gliomasphere models.

Conclusion

These data suggest that ASPM is involved in the malignant progression of gliomas, possibly through expansion of a cancer stem cell compartment, and is an attractive therapeutic target in glioblastoma multiforme.     

Seasonal modulation of free radical metabolism in estivating land snails Helix aspersa

We investigated the regulation of free radical metabolism in Helix aspersa snails during a cycle of 20-day estivation and 24-h arousal in summer in comparison with estivation/arousal in winter-snails. In winter-snails (J. Exp. Biol. 206, 675-685, 2003), we had already observed an increase in the selenium-dependent glutathione-peroxidase (Se-GPX) activity in foot muscle and hepatopancreas and in the contents of hepatopancreas GSH-equivalents (GSH-eq=GSH+2 GSSG) during estivation compared with 24-h aroused snails. Summer-estivation prompted a 3.6-fold increase in Se-GPX activity in hepatopancreas, though not in foot muscle. Total-superoxide dismutase and catalase activities in hepatopancreas decreased (by 30-40%) during summer-estivation; however, no changes occurred in the activities of glutathione reductase, glutathione S-transferase and glucose-6-phosphate dehydrogenase in the two organs. GSH-eq levels were increased (by 54%) in foot muscle during estivation, but were unchanged in hepatopancreas. In contrast with winter-snails, oxidative stress markers (lipid peroxidation, carbonyl protein, and the GSSG/GSH-eq ratio) were unaltered during estivation/arousal in summer. These results demonstrate that seasonality modulates not only the absolute activities/levels of antioxidants (enzymes and GSH-eq) in H. aspersa, but also the regulatory process that controls the snail's antioxidant capacity during estivation/arousal. These results suggest that H. aspersa has an "internal clock" controlling the regulation of free radical metabolism in the different seasons.     

Compartment- and malignance-dependent up-regulation of γ-glutamyltranspeptidase and dipetidylpeptidase-IV activity in human brain gliomas

γ-Glutamyltranspeptidase (GGT, syn. γ-Glutamyltransferase) and dipeptidylpeptidase-IV (DPP-IV) activity participates in metabolic and growth control of normal and tumor cells by processing biologically active peptides. Here, we report on up-regulation of these enzymes in human brain gliomas determined by catalytic enzyme histochemistry and immunocytochemistry. Higher activity of GGT was found in 50%, 68% and 81% of WHO grade II, III and IV tumors, respectively. The process started at/near the microvasculature, from where it spread to the parenchyma. On average, the enzyme activity in grade II, III and IV gliomas exceeded controls 2.0, 3.0 and 3.5-fold, respectively. Up-regulation of DPP-IV-like activity also started at the microvasculature, but mainly in pericytes and mononuclear-like cells around the vessels and dispersed in the parenchyma. Marked elevation of this enzyme activity, comprising also tumor parenchyma, occurred only in grade IV glioblastomas (65% patients; 3.6 times above controls) which can, therefore, help in their differentiation from grade III gliomas. The increase of total DPP-IV-like activity also included its two enzymatic homologs, the canonical DPP-IV/CD26 and FAP-1α. The increase in GGT is supposed to be a tumor grade dependent response of microvasculature and tumor astrocytes to stress induced by tissue hypoxia and/or the metabolic aberrancies. The increase in DPP-IV-like activity in high-grade tumors can be attributed to inflammatory/scavenging processes performed by the mononuclear-like cells and, in glioblastomas, also to regressive changes in the structure and function of the microvasculature and tumor parenchyma, including astrocyte stress response. The inverse relationship between DPP-IV-like activity and Ki67 in most glioblastomas and shorter survival time of patients with low activity of this enzyme also suggest its anti-oncogenic effects.     

Prognostic implication of histological oligodendroglial tumor component: clinicopathological analysis of 111 cases of malignant gliomas

The favorable prognosis of high-grade oligodendroglial tumor such as glioblastoma (GBM) with oligodendroglioma component (GBMO) has been suggested; however, the studies which examine the prognostic significance of oligodendroglial tumor were limited. In this study, we performed a histopathology-based reevaluation of 111 cases of high grade gliomas according to the latest World Health Organization (WHO), and compared the clinical outcomes between oligodendroglial tumors and pure astrocytic tumors. The survival analysis revealed that the patients with high grade oligodendroglial tumor including GBMO significantly indicated better prognosis compared to the patients with high grade pure astrocytic tumors (GBM and AA, anaplastic astrocytoma) as expected, and the obtained survival curves were almost identical to those from the patients with conventional Grade III or Grade IV tumors, respectively. Moreover, if the cases of oligodendroglial tumor were histopathologically excluded, the patients with AA exhibited extremely poor prognosis which was similar to that of GBM, suggesting that the histological identification of oligodendroglial tumor component, even partially, prescribe the prognosis of high grade glioma patients. This is the prominent report of retrospective clinicopathological analysis for high-grade gliomas throughout Grade III and IV, especially referring to the prognostic value of histological oligodendroglial tumor component; in addition, our results might offer an alternative aspect for the grading of high-grade astrocytic/oligodendroglial tumors.     

Radiation induced oxidative stress: II Studies in liver as a distant organ of tumor bearing mice

Since the radiation dose tolerance of normal tissues/organs away from the site of tumor influences the success of radiation therapy of cancer, and antioxidant status is likely to be one of the factors to determine the tolerance; the radioresponse of antioxidant enzymes has been examined in the liver as a representative distant organ in the tumorbearing mice.Swiss albino male mice (7–8 weeks old) with Ehrlich solid tumor in the thigh pad were irradiated with different doses of radiation (0–9 Gy) at a dose rate of 0.0153 Gy/s and the specific activities of enzymes involved in the free radical metabolism were determined in the liver. Except GST, the activities of SOD, DTD and Gly I as well as the GSH content were found to be higher in the liver of tumorbearing mice compared to the nontumor bearing mice. The catalase activity progressively decreased with dose in both the groups of mice. However, the activity was relatively higher in the liver of tumor bearing mice than the control. Thus, the radioresponse of antioxidant enzymes seemed to be significantly different in the liver of tumorburdened mice compared to controls. The enhanced activities might be due to relatively more damage caused by radiation. The higher levels of NO· and peroxidative damage in the liver of tumorbearing mice probably suggest this possibility. These findings of the present work might have some serious implications as the increased radiationdamage of the distant normal organs (due to tumor burden) is likely to adversely affect the therapeutic gain.     

Hydroxyl free radicals generated by vanadyl[IV] induce cell blebbing in mitotic human Chang liver cells

Vanadium has recently been reported to induce interphase and M-phase (mitotic) programmed cell death via the generation of hydroxyl free radicals (OH*). In this paper, the effects of antioxidants on: (a) vanadyl[IV]-generated OH* free radical levels; and (b) cellular glutathione in vanadyl [IV]-treated Chang liver cells were evaluated. The surface morphology of vanadyl-treated mitotic cells was studied by confocal and scanning microscopy. The free radical scavengers zinc chloride, glucose and thiourea reduced the levels of vanadyl-induced OH* free radicals and partially prevented the depletion of cellular glutathione. Concurrent with OH* free radical production, vanadyl-treated telophase cells exhibited excessive cell blebbing and cell shrinkage. The morphological features demonstrated in vanadyl-induced mitotic programmed cell death as a consequence of oxidative stress is novel.     

3.0T 1H-MRS对脑胶质瘤及脑转移瘤的鉴别诊断

目的：利用3.0T氢质子磁共振波谱对胶质瘤和转移瘤的肿瘤组织区、瘤周水肿区进行细胞代谢物水平的检测,试图找出胶质瘤和脑转移瘤的鉴别诊断的依据,以及胶质瘤高、低级别组间的差别。方法：对经病理证实的20例高级别胶质瘤组、16例低级别胶质瘤组和19例脑转移瘤组患者,先行MRI平扫及增强扫描,波谱均在增强扫描的基础上获得,使用MR点分辨波谱序列,检测肿瘤组织区、瘤周水肿组织区NAA/Cr、Cho/Cr、NAA/Cho、NAA、Cho、Cr、Lip/Lac等值,进行比较。结果：（1）高级别胶质瘤与转移瘤在肿瘤组织区NAA/Cr代谢物浓度的比值有统计学意义。（2）高、低级别胶质瘤肿瘤组织内Cho/Cr比值有统计学意义。（3）转移瘤与高、低级别胶质瘤在瘤周水肿区NAA/Cr,以及低级别胶质瘤与转移瘤Cho/Cr代谢物浓度的比值有统计学意义;高级别胶质瘤与转移瘤瘤周区NAA代谢物浓度有明显差异。（4）胶质瘤高、低级别组间在肿瘤周围区NAA峰、Cho峰及NAA/Cho Cho/Cr代谢物浓度比值有统计学意义。（5）高级别胶质瘤和转移瘤分别与低级别胶质瘤在肿瘤组织区及瘤周水肿区Lip/Lac有显著性差异（P〈0.01）。结论：利用氢质子波谱可对胶质瘤和转移瘤进行鉴别诊断;Cho/Cr及NAA/Cho比值可对胶质瘤进行分级;Lip/Lac峰的出现与肿瘤的恶性度呈正相关,但不特异。     

Regulation of Free Radical Processes by Delta-Sleep Inducing Peptide in Rat Tissues under Cold Stress

An intraperitoneal injection of an exogenous delta-sleep inducing peptide (DSIP) at a dose of 12 g/100 g body weight shifted the prooxidant–antioxidant balance of free radical process (FRP) in tissues and erythrocytes of rats: the activities of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase) and the concentrations of antioxidants (reduced glutathione in particular) increased. The DSIP stimulated the myeloperoxidase activity in blood neutrophils and had no effect on the activity of xanthine oxidase, a prooxidant enzyme, in the brain and liver. Cold stress displaced the prooxidant–antioxidant balance by increasing the xanthine oxidase activity in tissues and decreasing the myeloperoxidase activity in blood neutrophils; it also inhibited the enzyme antioxidant activities in tissues and erythrocytes that was neutralized by an increased ceruloplasmin activity in blood plasma and by an elevated level of antioxidants in rat blood and tissues. Preliminary administration of DSIP to animals exposed to cold stress restored the prooxidant–antioxidant balance: it normalized the myeloperoxidase activity in blood neutrophils, decreased the xanthine oxidase activity, and increased the activity of antioxidant enzymes in tissues and erythrocytes restoring the antioxidant level. The molecular regulation mechanism of free radical processes by DSIP in tissues under stressful conditions is discussed.     

A study of glutathione status in the blood and tissues of patients with breast cancer

Glutathione plays an important role in the antioxidant system that is required for the maintenance of the redox status of the cell, defence against free radicals and detoxification of toxic compounds. Reduced glutathione (redGSH) can be converted to oxidized glutathione (GSSG) during oxidative stress. The ratio of redGSH/total glutathione can be regarded as an index of the redox status and a useful indicator of disease risks. We conducted experiments by the capillary zone electrophoresis method to investigate the alterations of the glutathione status in the blood and tissue samples from patients with breast cancer. The results showed that the levels of redGSH, GSSG, total glutathione and the ratio of redGSH/total glutathione were significantly decreased in the blood of the patients with breast cancer compared to those of the control subjects. The levels of various forms of glutathione were lower and more pronounced in stage III. In contrast, the levels of redGSH, GSSG, total glutathione and the redGSH/total glutathione ratio in breast cancer tissues were significantly increased relative to those of the adjacent cancer-free tissues, especially in stage II. We suggest that the high redGSH levels are associated with the enhancement of cell proliferation and resistance to apoptosis in the cancer cells, and the loss of the large amount of erythrocyte redGSH may be due to increased detoxification capacities and defence against oxidative stress. We propose that redGSH should be regarded as an important biochemical parameter for detecting breast malignancy.     

Ascorbate oxidation reduction in Helicoverpa zea as a scavenging system against dietary oxidants

We provide evidence of an important role for ascorbate free radical (AFR) reductase, dehydroascorbate (DHA) reductase, glutathione, and glutathione reductase as components of an oxidant-scavenging system in the midgut of larval Helicoverpa zea. Also, midgut ortho-quinone reductase is a potentially important constituent of the protective system against quinones. The midgut activities of AFR reductase, DHA reductase, glutathione reductase, and ortho-quinone reductase were, respectively, 168, 22.1, 6, and 39.5 nmol/min/mg protein. The relatively high activity of these enzymes in the midgut provides circumstantial evidence for a protective mechanism utilizing ascorbate as an antioxidant and glutathione and/or NADPH as reductants. To our knowledge, the enzymes AFR reductase and DHA reductase have not been reported in insects. The particular relevance of this system to antioxidant protection, and in particular to the detoxication of quinones formed in damaged leaf tissues, is discussed.     

Antioxidant system in Uromastyx philbyi during hibernation and activity periods

Hibernation is an extreme physiological state characterized by profound decreases in oxidative metabolism and body temperature during bouts of prolonged torpor, interrupted by brief periods of arousal with sudden increases in oxidative metabolism, with alterations in antioxidant defenses. We monitored the activities of antioxidant enzymes and oxidative stress during hibernation and activity in Uromastyx philbyi. 20 animals were used, 10 of which were collected in the hibernation season (group I) and the other 10 collected during the active period (group II). Blood, liver, brown adipose tissue (BAT) and brain samples were used to determine free radical and antioxidant levels. The results indicated a significant decrease of free radicals and increase of vitamin C, especially in serum during hibernation. In contrast, during the active period free radicals, enzymatic antioxidants as glutathione peroxidase (GPX), glutathione reductase (GR), superoxide dismutase (SOD) and catalase (CAT) and non-enzymatic antioxidants as reduce glutathione (GSH) and vitamin E increased in all studied tissues. It can be concluded that Uromastyx philbyi has a strong antioxidant defense system that protects it from the injurious effects of free radicals either at the periods of arousal or during activity periods.     

Putrescine alleviation of growth in salt stressed Brassica juncea by inducing antioxidative defense system

Seedlings of Indian mustard (Brassica juncea L.cv. RH-30) grown in controlled condition (irradiance 75 Wm(-2), RH 60-70% and temp. 25 +/- 2 degrees C) for 7d and watered with Hoagland's solution containing different level of NaCL (50-250 mmol/L NaCl) with or without putrescine (PUT, 0.1 mmol/L) were examined for PUT amelioration of NaCl induced inhibition in seedling growth by altering activity of antioxygenic enzymes and level of free radicals in the leaves. Salinity caused reduction in seedling growth and biomass accumulation was parallel to increased superoxide (*O2-), hydrogen peroxide (H2O2) levels, lipid peroxidation (MDA content) and electrolyte leakage in leaf tissues which were reversed significantly by PUT. The antioxygenic enzymes viz superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX) and glutathione reductase (GR) were differentially altered, depending on salt level. PUT induction of enzyme was in the following order APX>GR>CAT>SOD>POD in leaf tissues of salt stressed seedlings. PUT increased the level of glutathione and carotenoids in leaf tissues. This finding suggests that PUT might be activating antioxygenic enzymes and elevating antioxidants there by controlling free radical generation, hence preventing membrane peroxidation and denaturation of biomolecules resulting into improved seedling growth under salinity.     

Inhibitory effects of Azadirachta indica on DMBA-induced skin carcinogenesis in Balb/c mice

Male Balb/c mice were divided into four groups on the basis of their respective treatments wherein mice of Group I served as controls. For induction of skin tumors, mice of Group II and IV were injected sub-cutaneously with 7,12-dimethylbenz(a)anthracene (DMBA). Mice of Group III and IV were administered aqueous Azadirachta indica leaf extract (AAILE) thrice a week throughout the experiment. After 14 weeks of the first DMBA injection, Group II and IV mice developed tumors. In the tumor-bearing mice that received AAILE (Group IV), a significant reduction in mean tumor burden and tumor volume was observed. The tumors were confirmed to be papillomas and interestingly, the extent of hyper-chromatia was observed to be much more in skin tumors of Group II mice vis a vis the mice receiving AAILE. An increase in the extent of lipid peroxidation was observed in tumorous tissue of Group IV when compared to that of Group II mice. Glutathione (GSH) content and the activities of GSH-based antioxidant enzymes viz. glutathione peroxidase (GPx) and glutathione reductase (GR) increased significantly in the skin tissues of all the groups of mice when compared to control counterparts. Catalase activity was found to decrease significantly in the skin of mice, which received AAILE treatment only (Group III). Activity of super-oxide dismutase (SOD) decreased significantly in all the tumorous tissues (Group II and IV mice). In light of the above observations, the role of AAILE in inhibition of DMBA-induced skin carcinogenesis is discussed in the present study.     

Development of Mechanisms of Protection Against Oxidative Stress in Doxorubicin-Resistant Rat Tumoral Cells in Culture

We have compared some mechanisms involved in the defense against doxorubicin-induced free radical damage in rat hepatoma and glioblastoma cell lines and their doxorubicin-resistant variants presenting an overexpression of the multidrug resistance gene.

Immediate in vivo production of malondialdehyde was minor and was not different in sensitive and resistant cells. Alpha-tocopherol was undetectable in all cell lines. Glutathione levels were not different in sensitive and resistant cells and these levels did not vary upon doxorubicin treatment. Resistant cells exhibited either a 50% decrease (hepatoma) or a 25% increase (glioblastoma) of glutathione-S-transferase activity. Glutathione reductase presented no important change upon acquisition of resistance. In contrast, selenium-dependent glutathione peroxidase activity was consistently 2-6-fold increased in the resistant cells, which suggests a magnification of protection mechanisms against hydroxyle radical formation from H₂O₂ in resistant cells. Depletion of glutathione levels by buthionine sulfoximine sensitized hepatoma resistant cells to doxorubicin, but had no effect on doxorubicin cytotoxicity to glioblastoma cells.     

Development of Mechanisms of Protection Against Oxidative Stress in Doxorubicin-Resistant Rat Tumoral Cells in Culture

We have compared some mechanisms involved in the defense against doxorubicin-induced free radical damage in rat hepatoma and glioblastoma cell lines and their doxorubicin-resistant variants presenting an overexpression of the multidrug resistance gene.

Immediate in vivo production of malondialdehyde was minor and was not different in sensitive and resistant cells. Alpha-tocopherol was undetectable in all cell lines. Glutathione levels were not different in sensitive and resistant cells and these levels did not vary upon doxorubicin treatment. Resistant cells exhibited either a 50% decrease (hepatoma) or a 25% increase (glioblastoma) of glutathione-S-transferase activity. Glutathione reductase presented no important change upon acquisition of resistance. In contrast, selenium-dependent glutathione peroxidase activity was consistently 2-6-fold increased in the resistant cells, which suggests a magnification of protection mechanisms against hydroxyle radical formation from H₂O₂ in resistant cells. Depletion of glutathione levels by buthionine sulfoximine sensitized hepatoma resistant cells to doxorubicin, but had no effect on doxorubicin cytotoxicity to glioblastoma cells.