minocycline and Neuroblastoma

Neurotoxicity is an adverse effect patients experience during colistin therapy. The development of effective neuroprotective agents that can be co-administered during polymyxin therapy remains a priority area in antimicrobial chemotherapy. The present study investigates the neuroprotective effect of the synergistic tetracycline antibiotic minocycline against colistin-induced neurotoxicity.. The impact of minocycline pretreatment on colistin-induced apoptosis, caspase activation, oxidative stress and mitochondrial dysfunction were investigated using cultured mouse neuroblastoma-2a (N2a) and primary cortical neuronal cells.. Colistin-induced neurotoxicity in mouse N2a and primary cortical cells gives rise to the generation of reactive oxygen species (ROS) and subsequent cell death via apoptosis. Pretreatment of the neuronal cells with minocycline at 5, 10 and 20 μM for 2 h prior to colistin (200 μM) exposure (24 h), had an neuroprotective effect by significantly decreasing intracellular ROS production and by upregulating the activities of the anti-ROS enzymes superoxide dismutase and catalase. Minocycline pretreatment also protected the cells from colistin-induced mitochondrial dysfunction, caspase activation and subsequent apoptosis. Immunohistochemical imaging studies revealed colistin accumulates within the dendrite projections and cell body of primary cortical neuronal cells.. To our knowledge, this is first study demonstrating the protective effect of minocycline on colistin-induced neurotoxicity by scavenging of ROS and suppression of apoptosis. Our study highlights that co-administration of minocycline kills two birds with one stone: in addition to its synergistic antimicrobial activity, minocycline could potentially ameliorate unwanted neurotoxicity in patients undergoing polymyxin therapy.

Topics: Animals; Apoptosis; Caspases; Catalase; Cell Line, Tumor; Cells, Cultured; Cerebral Cortex; Colistin; Drug Synergism; Enzyme Activation; Mice; Minocycline; Mitochondria; Neuroblastoma; Neurons; Neuroprotective Agents; Oxidative Stress; Reactive Oxygen Species; Superoxide Dismutase

Minocycline is a tetracycline antibiotic increasingly recognized in psychiatry for its pleiotropic anti-inflammatory and neuroprotective potential. While underlying mechanisms are still incompletely understood, several lines of evidence suggest a relevant functional overlap with retinoic acid (RA), a highly potent small molecule exhibiting a great variety of anti-inflammatory and neuroprotective properties in the adult central nervous system (CNS). RA homeostasis in the adult CNS is tightly controlled through local RA synthesis and cytochrome P450 (CYP450)-mediated inactivation of RA. Here, we hypothesized that minocycline may directly affect RA homeostasis in the CNS via altering local RA degradation.. We used in vitro RA metabolism assays with metabolically competent synaptosomal preparations from murine brain and human SH-SY5Y neuronal cells as well as viable human SH-SY5Y neuroblastoma cell cultures.. We revealed that minocycline potently blocks RA degradation as measured by reversed-phase high-performance liquid chromatography and in a viable RA reporter cell line, even at low micromolar levels of minocycline.. Our findings provide evidence for enhanced RA signalling to be involved in minocycline's pleiotropic mode of action in the CNS. This novel mode of action of minocycline may help in developing more specific and effective strategies in the treatment of neuroinflammatory or neurodegenerative disorders.

Topics: Animals; Brain; Cell Line, Tumor; Cytochrome P-450 Enzyme System; Humans; Male; Minocycline; Neuroblastoma; Neurons; Rats; Rats, Wistar; Regression Analysis; Tretinoin

As the first member of glycylcycline bacteriostatic agents, tigecycline is approved as a novel expanded-spectrum antibiotic, which is clinically available. However, accumulating evidence indicated that tigecycline was provided with the potential application in cancer therapy. In this paper, tigecycline was shown to exert an anti-proliferative effect on neuroblastoma cell lines. Furthermore, it was found that tigecycline induced G1-phase cell cycle arrest instead of apoptosis by means of Akt pathway inhibition. In neuroblastoma cell lines, the Akt activator insulin-like growth factor-1 (hereafter referred to as IGF-1) reversed tigecycline-induced cell cycle arrest. Besides, tigecycline inhibited colony formation and suppressed neuroblastoma cells xenograft formation and growth. After tigecycline treatment in vivo, the Akt pathway inhibition was confirmed as well. Collectively, our data provided strong evidences that tigecycline inhibited neuroblastoma cells growth and proliferation through the Akt pathway inhibition in vitro and in vivo. In addition, these results were supported by previous studies concerning the application of tigecycline in human tumors treatment, suggesting that tigecycline might act as a potential candidate agent for neuroblastoma treatment.

Topics: Animals; Anti-Bacterial Agents; Apoptosis; Biomarkers, Tumor; Blotting, Western; Cell Proliferation; Flow Cytometry; Fluorescent Antibody Technique; G1 Phase Cell Cycle Checkpoints; Humans; In Vitro Techniques; Insulin-Like Growth Factor I; Mice; Mice, SCID; Minocycline; Neuroblastoma; Phosphorylation; Proto-Oncogene Proteins c-akt; Signal Transduction; Tigecycline; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Venezuelan equine encephalitis (VEE) virus causes an acute central nervous system infection in human and animals. Melatonin (MLT), minocycline (MIN) and ascorbic acid (AA) have been shown to have antiviral activities in experimental infections; however, the mechanisms involved are poorly studied. Therefore, the aim of this study was to determine the effects of those compounds on the viral titers, NO production and lipid peroxidation in the brain of mice and neuroblastoma cultures infected by VEE virus. Infected mouse (10 LD50) were treated with MLT (500 μg/kg bw), MIN (50mg/kg bw) or AA (50mg/kg bw). Infected neuroblastoma cultures (MOI: 1); MLT: 0.5, 1, 5mM, MIN: 0.1, 0.2, 2 μM or AA: 25, 50, 75 μM. Brains were obtained at days 1, 3 and 5. In addition, survival rate of infected treated mice was also analyzed. Viral replication was determined by the plaque formation technique. NO and lipid peroxidation were measured by Griess׳ reaction and thiobarbituric acid assay respectively. Increased viral replication, NO production and lipid peroxidation were observed in both, infected brain and neuroblastoma cell cultures compared with uninfected controls. Those effects were diminished by the studied treatments. In addition, increased survival rate (50%) in treated infected animals compared with untreated infected mice (0%) was found. MLT, MIN and AA have an antiviral effect involving their anti-oxidant properties, and suggesting a potential use of these compounds for human VEE virus infection.

Topics: Animals; Antiviral Agents; Ascorbic Acid; Brain; Cell Line, Tumor; Disease Models, Animal; Dose-Response Relationship, Drug; Encephalitis Virus, Venezuelan Equine; Encephalomyelitis, Venezuelan Equine; Lipid Peroxidation; Male; Melatonin; Mice; Minocycline; Neuroblastoma; Neuroprotective Agents; Nitric Oxide; Oxidative Stress; Survival Rate; Treatment Outcome; Viral Load

HFE gene variants are relatively common genetic variants in Caucasians. The H63D HFE genetic variant has been repeatedly associated with a number of neurodegenerative diseases. We developed neuroblastoma cell lines expressing different HFE polymorphisms to explore the mechanisms behind these associations. Here we tested the hypothesis that cells with the H63D variant have a phenotype that promotes glutamate toxicity. In support of this hypothesis, expression of H63D HFE is associated with increased calcium-induced glutamate secretion and decreased cellular glutamate uptake. The polymorphism-associated changes in glutamate secretion were mimicked by altering cellular iron. Additionally, intracellular calcium is altered in a genotype-specific manner which could further impact glutamate secretion. HFE-dependent effects on glutamate uptake were confirmed in astrocytoma cell lines with endogenous expression of HFE. The ability of minocycline and the antioxidant Trolox to increase glutamate uptake differed by HFE genotype and implicate oxidative stress in glutamate regulation. This study demonstrates HFE cellular effects that extend beyond iron regulation, and suggests that H63D HFE may promote glutamate toxicity.

Topics: Analysis of Variance; Calcium; Cell Line, Tumor; Deferoxamine; Enzyme Inhibitors; Ferric Compounds; Gene Expression Regulation, Neoplastic; Glutamate Plasma Membrane Transport Proteins; Glutamic Acid; Glutaminase; Hemochromatosis Protein; Histocompatibility Antigens Class I; Humans; Intracellular Fluid; Iron; Membrane Proteins; Minocycline; Neuroblastoma; Polymorphism, Genetic; Quaternary Ammonium Compounds; Siderophores; Sodium; Tacrine; Transfection; Tritium; Vesicular Glutamate Transport Protein 1

Several in vitro and in vivo studies addressed the identification of molecular determinants of the neuronal death induced by PrP(Sc) or related peptides. We developed an experimental model to assess PrP(Sc) neurotoxicity using a recombinant polypeptide encompassing amino acids 90-231 of human PrP (hPrP90-231) that corresponds to the protease-resistant core of PrP(Sc) identified in prion-infected brains. By means of mild thermal denaturation, we can convert hPrP90-231 from a PrP(C)-like conformation into a PrP(Sc)-like structure. In virtue of these structural changes, hPrP90-231 powerfully affected the survival of SH-SY5Y cells, inducing caspase 3 and p38-dependent apoptosis, while in the native alpha-helix-rich conformation, hPrP90-231 did not induce cell toxicity. The aim of this study was to identify drugs able to block hPrP90-231 neurotoxic effects, focusing on minocycline, a tetracycline with known neuroprotective activity. hPrP90-231 caused a caspase 3-dependent apoptosis via the blockade of ERK1/2 activation and the subsequent activation of p38 MAP kinase. We propose that hPrP90-231-induced apoptosis is dependent on the inhibition of ERK1/2 responsiveness to neurotrophic factors, removing a tonic inhibition of p38 activity and resulting in caspase 3 activation. Minocycline prevented hPrP90-231-induced toxicity interfering with this mechanism: the pretreatment with this tetracycline restored ERK1/2 activity and reverted p38 and caspase 3 activities. The effects of minocycline were not mediated by the prevention of hPrP90-231 structural changes or cell internalization (differently from Congo Red). In conclusion, minocycline elicits anti-apoptotic effects against the neurotoxic activity of hPrP90-231 and these effects are mediated by opposite modulation of ERK1/2 and p38 MAP kinase activities.

Topics: Animals; Apoptosis; Caspases; Cell Line, Tumor; Cell Survival; Dose-Response Relationship, Drug; Drug Interactions; Enzyme Activation; Enzyme Inhibitors; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Humans; Minocycline; Mitogen-Activated Protein Kinase 3; Neuroblastoma; Neurotoxins; p38 Mitogen-Activated Protein Kinases; Peptide Fragments; Phosphorylation; Prions; Signal Transduction; Time Factors

Minocycline is neuroprotective in animal models of a number of acute CNS injuries, neurodegenerative diseases and CNS infection. While anti-inflammatory and anti-apoptotic effects of Minocycline have been characterized, the molecular basis for the neuroprotective effects of Minocycline remains unclear. We report here that Minocycline and two classical antioxidant compounds inhibit the Japanese Encephalitis Virus (JEV)-induced free radical generation in mouse neuroblastoma. In cultures of Neuro2a (N2a) cells infected with JEV for up to 24h, the number of cells undergoing cell death was also reduced by Minocycline (20 microM). JEV infection resulted in increased oxidative stress, as revealed by an increase in the fluorescence intensity for 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate (CM-H2DCFDA), a reactive oxygen species (ROS) indicator. Minocycline at 20 microM inhibited this ROS production. Cells were moderately protected from JEV-induced death by diphenyleneiodonium (DPI), an inhibitor of flavon-containing enzyme inhibitor, whereas common antioxidants such as N-acetyl-cysteine (NAC) turned out to be ineffective. Direct antioxidant property of Minocycline and reference antioxidant compounds is evaluated by LDH assay, ROS measurement and mitochondrial membrane potential measurement. Our findings suggest that Minocycline reduces the neuronal damage seen in JEV infection in neuronal cell culture models at least in part through inhibition of oxidative stress.

Topics: Acetylcysteine; Animals; Anisotropy; Anti-Bacterial Agents; Antioxidants; Blotting, Western; Brain Neoplasms; Cell Death; Cell Line, Tumor; Encephalitis, Japanese; Enzyme Inhibitors; Free Radicals; In Situ Nick-End Labeling; L-Lactate Dehydrogenase; Membrane Fluidity; Membrane Potentials; Mice; Mice, Inbred BALB C; Minocycline; Mitochondrial Membranes; Neuroblastoma; Onium Compounds; Reactive Oxygen Species

Minocycline, a semisynthetic derivative of tetracycline, displays beneficial activity in neuroprotective in models including, Parkinson disease, spinal cord injury, amyotrophic lateral sclerosis, Huntington disease and stroke. The mechanisms by which minocycline inhibits apoptosis remain poorly understood. In the present report we have investigated the effects of minocycline on mitochondria, due to their crucial role in apoptotic pathways. In mitochondria isolated suspensions, minocycline failed to block superoxide-induced swelling but was effective in blocking mitochondrial swelling induced by calcium. This latter effect might be mediated through dissipation of mitochondrial transmembrane potential and blockade of mitochondrial calcium uptake. Consistently, minocycline fails to protect SH-SY5Y cell cultures against reactive oxygen species-mediated cell death, including malonate and 6-hydroxydopamine treatments, but it is effective against staurosporine-induced cytotoxicity. The effects of this antibiotic on mitochondrial respiratory chain complex were also analyzed. Minocycline did not modify complex IV activity, and only at the higher concentration tested (100 microM) inhibited complex II/III activity. Other members of the minocycline antibiotic family like tetracycline failed to induce these mitochondrial effects.

Topics: Animals; Calcium; Cell Count; Cell Death; Cell Line, Tumor; Cell Survival; Dose-Response Relationship, Drug; Drug Interactions; Enzyme Inhibitors; Glutathione; Humans; Membrane Potentials; Minocycline; Mitochondria; Mitochondrial Swelling; NADP; Neuroblastoma; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; Spectrophotometry; Staurosporine; Tetrazolium Salts; Thiazoles