3-nitrotyrosine and Glioma

Free radicals play a major role in gliomas. By combining immuno-spin-trapping (IST) and molecular magnetic resonance imaging (mMRI), in vivo levels of free radicals were detected within mice bearing orthotopic GL261 gliomas. The nitrone spin trap DMPO (5,5-dimethyl pyrroline N-oxide) was administered prior to injection of an anti-DMPO probe (anti-DMPO antibody covalently bound to a bovine serum albumin (BSA)-Gd (gadolinium)-DTPA (diethylene triamine penta acetic acid)-biotin MRI contrast agent) to trap tumor-associated free radicals. mMRI detected the presence of anti-DMPO adducts by either a significant sustained increase (p<0.001) in MR signal intensity or a significant decrease (p<0.001) in T1 relaxation, measured as %T1 change. In vitro assessment of the anti-DMPO probe indicated a significant decrease (p<0.0001) in T1 relaxation in GL261 cells that were oxidatively stressed with hydrogen peroxide, compared to controls. The biotin moiety of the anti-DMPO probe was targeted with fluorescently-labeled streptavidin to locate the anti-DMPO probe in excised brain tissues. As a negative control a non-specific IgG antibody covalently bound to the albumin-Gd-DTPA-biotin construct was used. DMPO adducts were also confirmed in tumor tissue from animals administered DMPO, compared to non-tumor brain tissue. GL261 gliomas were found to have significantly increased malondialdehyde (MDA) protein adducts (p<0.001) and 3-nitrotyrosine (3-NT) (p<0.05) compared to normal mouse brain tissue, indicating increased oxidized lipids and proteins, respectively. Co-localization of the anti-DMPO probe with either 3-NT or 4-hydroxynonenal was also observed. This is the first report regarding the detection of in vivo levels of free radicals from a glioma model.

Topics: Albumins; Animals; Brain Neoplasms; Contrast Media; Cyclic N-Oxides; Disease Models, Animal; Free Radicals; Gadolinium DTPA; Glioma; Immunoglobulin G; Magnetic Resonance Imaging; Mice; Mice, Inbred C57BL; Nitrogen Oxides; Oxidation-Reduction; Radiography; Spin Labels; Spin Trapping; Tumor Cells, Cultured; Tyrosine

Diabetic complications can often affect the central nervous system since the chronic exposure to hyperglycemia can result in the production of high concentration of reactive oxygen species with subsequent damage of several cell structures such as the cytoskeleton. In order to antagonize the oxidative status many substances have been tested as antioxidants. In the present work attention has been focused on the possible nitrosative effect of hyperglycemia on microtubular network of neuroblastoma and glioma mortalized cell lines, testing the possible neuroprotective effect of testosterone.. Neuroblastoma (C1300) and glioma (C6) cell lines were cultured in the presence of 300 mM (C1300) or 310 mM (C6) D-glucose, with or without 50 nM testosterone. After 72 hrs, morphology, growth rate, cell viability and catalase activity were evaluated. In addition, with the aim to detect any changes in the amount of tubulin isoforms, Western blot analysis was performed.. In D-glucose-exposed cells, it was found a down-regulation of tubulin isoforms and an increase in 3-nitro-L-tyrosine and subsequent modifications in cell morphology, growth rate, viability and catalase activity. All these changes were more severe in neuroblastoma than in glioma cell line. When testosterone was added to the medium, all the parameters were very similar to controls. This neuroprotective action was well-detectable in C1300 cells, whereas testosterone was not able to recover significantly in C6 cells.. Our results displayed: i) a selective action of high glucose on microtubules; ii) a different sensitivity to oxidative stress in neuronal and glial cells; iii) a different neuroprotective action of testosterone on neuronal and glial cells.

Topics: Androgens; Animals; Catalase; Cell Division; Cell Line, Transformed; Cell Survival; Down-Regulation; Drug Interactions; Glioma; Glucose; Mice; Microtubules; Neuroblastoma; Neuroglia; Neurons; Neuroprotective Agents; Oxidative Stress; Rats; Reactive Nitrogen Species; Testosterone; Tubulin; Tyrosine

Immunohistochemical and biochemical investigations showed that significant protein nitration occurs in human gliomas, especially in grade IV glioblastomas at the level of astrocytes and oligodendrocytes and neurones. Enhanced alpha-tubulin immunoreactivity was co-present in the same elements in the glioblastomas. Proteomic methodologies were employed to identify a nitrated protein band at 55 kDa as alpha-tubulin. Peptide mass fingerprinting procedures demonstrated that tubulin is nitrated at Tyr224 in grade IV tumour samples but is unmodified in grade I samples and in non-cancerous brain tissue. These results provide the first characterisation of endogenously nitrated tubulin from human tumour samples.

Topics: Aged; Astrocytes; Blotting, Western; Brain Neoplasms; Chromatography, High Pressure Liquid; Female; Glioma; Humans; Immunohistochemistry; Male; Middle Aged; Neurons; Proteomics; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Tubulin; Tyrosine

The amino acid analogue 3-nitrotyrosine (3-NT) is formed in neural cells as a result of the intense stimulation of NMDA glutamate receptors. 3-NT is involved in the pathology of diverse neurodegenerative disorders. The aim of our work is to investigate the sensitivity of cultured neural and glial cells to 3-NT. We report the morphological changes detected on mouse neuroblastoma (C1300) and rat glioma (C6) cell lines cultured in a medium supplemented with different 3-NT concentrations. Western blot displayed a selective incorporation of 3-NT into a single protein that co-migrated with tubulin. Both cell lines showed morphological changes, nuclear suffering, decreased viability and growth inhibition (starting from 90 and 360 microM for C1300 and C6, respectively). Such effects were dose-dependent, though glioma cells showed severe alterations at higher 3-NT concentrations. Our results point out a higher 3-NT sensitivity in the neural cells studied in comparison with those of glial origin. The dramatic toxicity of 3-NT in neural cells suggests further investigations focused on the biochemical mechanisms at the roots of neurodegenerative diseases.

Topics: Animals; Cell Division; Cell Line; Cell Nucleus; Cell Size; Cell Survival; Dose-Response Relationship, Drug; Glioma; Mice; Neuroblastoma; Neurodegenerative Diseases; Neuroglia; Neurons; Rats; Tubulin; Tyrosine

Based on previous findings of increased nitric oxide synthase (NOS) expression in human gliomas (4), we hypothesized that peroxynitrite, a highly reactive metabolite of nitric oxide (NO) and superoxide (O(*-)(2)), might be increased in these tumors in vivo. Here we demonstrate that nitrotyrosine (a footprint of peroxynitrite protein modification) is present in human malignant gliomas. Furthermore, we show that p53, a key tumor suppressor protein, has evidence of peroxynitrite-mediated modifications in gliomas in vivo. Experiments in vitro demonstrate that peroxynitrite treatment of recombinant wild-type p53 at physiological concentrations results in formation of higher molecular weight aggregates, tyrosine nitration, and loss of specific DNA binding. Peroxynitrite treatment of human glioma cell lysates similarly resulted in selective tyrosine nitration of p53 and was also associated with loss of p53 DNA binding ability. These data indicate that tyrosine nitration of proteins occurs in human gliomas in vivo, that p53 may be a target of peroxynitrite in these tumors, and that physiological concentrations of peroxynitrite can result in a loss of p53 DNA binding ability in vitro. These findings raise the possibility that peroxynitrite may contribute to loss of wild-type p53 functional activity in gliomas by posttranslational protein modifications.

Topics: Blotting, Western; Electrophoresis, Polyacrylamide Gel; Glioblastoma; Glioma; Humans; Immunohistochemistry; Oligonucleotides; Peroxynitrous Acid; Protein Processing, Post-Translational; Recombinant Proteins; Tumor Cells, Cultured; Tumor Suppressor Protein p53; Tyrosine

Pretreatment of interferon-gamma and lipopolysaccharides made C6 glioma cells highly vulnerable to glucose deprivation. Neither 12 h of glucose deprivation nor 2-day treatment with interferon-gamma (100 U/ml) and lipopolysaccharides (1 microg/ml) altered the viability of C6 glioma cells. However, significant death of immunostimulated C6 glioma cells was observed after 5 h of glucose deprivation. The augmented death was prevented by dehydroepiandrosterone (DHEA) treatment during immunostimulation, but not by DHEA treatment during glucose deprivation. DHEA reduced the rise in nitrotyrosine immunoreactivity, a marker of peroxynitrite, and superoxide production in glucose-deprived immunostimulated C6 glioma cells. DHEA, however, did not protect glucose-deprived C6 glioma cells from the exogenously produced peroxynitrite by 3-morpholinosydnonimine. Further, DHEA did not alter the production of total reactive oxygen species and nitric oxide in immunostimulated C6 glioma cells. Superoxide dismutase (SOD) and the synthetic SOD mimetic Mn(III)tetrakis (4-benzoic acid) porphyrin inhibited the death of glucose-deprived immunostimulated C6 glioma cells. In addition, a superoxide anion generator paraquat reversed the protective effect of DHEA on the augmented death. The data indicate that DHEA prevents the glucose deprivation-evoked augmented death by inhibiting the production of superoxide anion in immunostimulated C6 glioma cells.

Topics: Adjuvants, Immunologic; Animals; Astrocytes; Brain; Brain Ischemia; Cell Death; Cytokines; Dehydroepiandrosterone; Enzyme Inhibitors; Free Radical Scavengers; Glioma; Glucose; Herbicides; Humans; Interferon-gamma; Lipopolysaccharides; Metalloporphyrins; Molsidomine; Neurons; Nitric Oxide; Oxidative Stress; Paraquat; Peroxynitrous Acid; Superoxide Dismutase; Tumor Cells, Cultured; Tyrosine