ucn-1028-c and Neuroblastoma

Potassium 2-(1-hydroxypentyl)-benzoate (dl-PHPB) has been shown to have potent neuroprotective effects, such as reducing the infarct volume and improving neurobehavioral deficits in the transient focal cerebral ischemic rat model. The present study is to evaluate the neuroprotective effect of dl-PHPB on hydrogen peroxide (H(2)O(2))-induced apoptosis and the possible mechanism in the human neuroblastoma SK-N-SH cells. Our results showed that dl-PHPB significantly attenuated H(2)O(2)-induced cell death, and reduced neuronal apoptosis. Dl-PHPB partially reversed the decrease of B-cell CLL/lymphoma 2 (Bcl-2) protein level induced by H(2)O(2). Furthermore, dl-PHPB inhibited the elevation of pro-apoptotic Bcl-2-associated X protein (Bax) and caspase3, and alleviated the down-regulation of protein kinase C alpha (PKCα). The PKC inhibitor, Calphostin C significantly attenuated the protective effects of dl-PHPB. The findings suggest that dl-PHPB may protect neurons against H(2)O(2)-induced apoptosis by modulating apoptosis-related proteins, and PKC signaling pathway may be involved in the neuroprotection of dl-PHPB.

Topics: Apoptosis; bcl-2-Associated X Protein; Benzoates; Caspase 3; Cell Death; Cell Line, Tumor; Down-Regulation; Humans; Hydrogen Peroxide; Naphthalenes; Neuroblastoma; Neurons; Neuroprotective Agents; Pentanes; Protein Kinase C-alpha; Proto-Oncogene Proteins c-bcl-2; Signal Transduction

Alzheimer's disease (AD) is the most common form of dementia. Oxidative stress is one of the earliest events in the neurological and pathological changes of AD. L-3-n-butyl-phthalide (L-NBP), an anti-cerebral ischemia agent, has been shown a potential in AD treatment. In this study, we investigated the neuroprotective effect of L-NBP on hydrogen peroxide (H₂O₂)-induced apoptosis in human neuroblastoma SK-N-SH cells. H₂O₂ significantly reduced cell viability and increased the number of apoptotic-like cells, indicating that H₂O₂ induced neurotoxicity. In addition, real-time PCR and western blot studies showed that Bcl-2 and Bcl-w expressions were decreased, and Bax expression was increased with H₂O₂ treatment. Moreover, protein kinase C (PKC) α expression was down-regulated after H₂O₂ treatment. All of these phenotypes induced by H₂O₂ were markedly reversed by L-NBP. Pretreatment with L-NBP significantly increased cell viability of H₂O₂-damaged cells, and reduced H₂O₂-induced neuronal apoptosis. L-NBP treatment at dose of 10 μM inhibited H₂O₂-induced down-regulation of Bcl-2, Bcl-w, and PKCα but also attenuated the overexpression of Bax. PKC inhibitor, calphostin C, significantly attenuated the protective effects of L-NBP. Our findings suggest that L-NBP may protect neurons against H₂O₂-induced apoptosis by modulating apoptosis-related genes and activating PKCα pathway.

Topics: Apoptosis; Apoptosis Regulatory Proteins; bcl-2-Associated X Protein; Benzofurans; Cell Line, Tumor; Cell Survival; Gene Expression; Humans; Hydrogen Peroxide; Naphthalenes; Neuroblastoma; Neuroprotective Agents; Protein Kinase C; Protein Kinase C-alpha; Protein Kinase C-epsilon; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-bcl-2; Signal Transduction

Regulation of surface insertion and internalization of AMPA and NMDA receptors has emerged as a key mechanism for the control of synaptic strength. Regulatory elements for synaptic kainate receptors (KARs) are, however, largely undetermined. We have found that SNAP25 is critical for the synaptic removal of KARs, acting via GluK5 (i.e., KA2) subunits. SNAP25 coimmunoprecipitates with protein complexes containing PICK1, GRIP1, and GluK5 and colocalizes with GluK5 in both hippocampal neurons and transfected HEK293 cells. In hippocampal slices, purified SNAP25 antibodies and blocking peptides caused a GluK5-dependent run-up of KARs-mediated EPSC (EPSC(KAR)) recorded from CA3 pyramidal neurons when included in the patch pipette and prevented activity-dependent long-term depression of EPSC(KAR). As EPSC(KAR) LTD, SNAP25/PICK1/GluK5 interactions are dynamically regulated by PKC.

Topics: Adaptor Proteins, Signal Transducing; Animals; Animals, Newborn; Calcium; Carrier Proteins; Cell Cycle Proteins; Cell Line, Transformed; Cell Line, Tumor; Electric Stimulation; Enzyme Inhibitors; Excitatory Amino Acid Antagonists; Excitatory Postsynaptic Potentials; Hippocampus; Humans; Immunoprecipitation; Luminescent Proteins; Mice; Mice, Inbred C57BL; Mice, Knockout; Naphthalenes; Nerve Tissue Proteins; Neural Pathways; Neuroblastoma; Neuronal Plasticity; Neurons; Neurotoxins; Nuclear Proteins; Patch-Clamp Techniques; Protein Transport; Pyridines; Rats; Receptors, Kainic Acid; Synapses; Synaptosomal-Associated Protein 25; Transfection; Vesicle-Associated Membrane Protein 2

Topics: 8-Bromo Cyclic Adenosine Monophosphate; Amides; Animals; Arachidonic Acid; Arachidonic Acids; Cyclic AMP; Dinoprostone; Endocannabinoids; Enzyme Activation; Ethanolamines; Genistein; GTP-Binding Proteins; Linoleic Acids; Macrophages; Mice; Naphthalenes; Neuroblastoma; Nitriles; Palmitic Acids; Phospholipases A; Polyunsaturated Alkamides; Second Messenger Systems; Staurosporine; Tumor Cells, Cultured; Tyrphostins; Virulence Factors, Bordetella

The expression of protein kinase C isoforms in the neuroblastoma cell line Neuro 2a has been studied. It is shown that Neuro 2a cells express alpha, delta, epsilon and zeta PKCs. Inhibition of cell proliferation by using protein kinase C inhibitors (H7 or calphostin C) or medium without glutamine affects markedly the pattern of PKC isoforms. All treatments reduced significantly (50-70%) the content of PKC alpha. None of the treatments altered PKC zeta or epsilon. The content of PKC delta was increased (88-120%) in cells treated with PKC inhibitors but was slightly reduced in cells incubated in medium without glutamine. However, none of the treatments affected the content of the corresponding mRNAs. Long-term treatment of synchronized cells with the phorbol ester PMA depletes PKC alpha but not PKC delta or zeta and only partially PKC epsilon. This treatment with PMA did not affect DNA synthesis, indicating that PKC alpha does not play a significant role in the control of proliferation of these cells.

Topics: Animals; Cell Division; Enzyme Inhibitors; Immunoblotting; Mice; Mice, Inbred Strains; Naphthalenes; Neuroblastoma; Polymerase Chain Reaction; Protein Kinase C

We investigated the intracellular events involved in the 3,3',5-triiodo-L-thyronine (T3)-induced accumulation in acetylcholinesterase (AChE) activity in neuroblastoma cells (neuro-2a) that overexpress the human thyroid receptor beta 1 (hTR beta 1). Treatment of these cells with T3 increased AChE activity and its mRNAs after a lag period of 24-48 h, and these levels increased through stabilization of the transcripts by T3. T3 had no effect on the transcriptional rate or processing of AChE transcripts. The protein kinase inhibitor H7 inhibited T3-induced accumulation in AChE activity and its mRNAs, whereas okadaic acid (a potent inhibitor of phosphatases 1 and 2A) potentiated the effect of T3. Okadaic acid and H7 have no effect on the binding of hTR beta 1 to T3 or the transcriptional rate of the AChE gene. Finally, treatment of cells with T3 stimulated cytosolic serine/threonine, but not tyrosine kinase, activities. The time course analysis reveals that the increase in serine/threonine activity precedes the effect of T3 on AChE mRNAs. These results suggest that activation of a serine/threonine protein kinase pathway might be a link between nuclear thyroid hormone receptor activation and stabilization of AChE mRNA.

Topics: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; 8-Bromo Cyclic Adenosine Monophosphate; Acetylcholinesterase; Animals; Cell Line; Dichlororibofuranosylbenzimidazole; Enzyme Inhibitors; Ethers, Cyclic; Humans; Isoquinolines; Kinetics; Mice; Naphthalenes; Neuroblastoma; Okadaic Acid; Phosphoprotein Phosphatases; Piperazines; Protein Binding; Protein Kinase Inhibitors; Protein Serine-Threonine Kinases; Protein-Tyrosine Kinases; Receptors, Thyroid Hormone; Recombinant Proteins; RNA, Messenger; Tetradecanoylphorbol Acetate; Transcription, Genetic; Transfection; Triiodothyronine; Tumor Cells, Cultured

Cross-regulation from the stimulatory phospholipase C to the adenylyl cyclase pathways was explored in neuroblastoma-glioma NG-108-15 cells in culture. Activation of protein kinase C by phorbol myristic acid resulted in a markedly attenuated activation of the inhibitory adenylyl cyclase response to delta-opiate agonists and epinephrine but not to the muscarinic agonist carbachol. The ability of okadaic acid to mimic the effects of phorbol myristic acid on the inhibitory response suggested a role for protein phosphorylation. Adenylyl cyclase activity from cells in which protein kinase C had been activated demonstrated a loss in the inhibitory adenylyl cyclase response at the level of the G-protein. Activation of protein kinase C prompted a 2-4-fold increase in phosphorylation of G1 alpha 2 in cells metabolically labeled with [32P]orthophosphate. The phosphate content of Gi alpha 2 was determined to be approximately 0.5 mol/mol subunit in the unstimulated cells and approximately 1.5 mol/mol subunit for cells in which protein kinase C was activated. The effects of okadaic acid, 4-alpha-phorbol, and calphostin C on inhibition of adenylyl cyclase in cells treated with phorbol myristic acid correlate with the effects of these agents on phosphorylation of Gi alpha 2. The time courses for attenuation of inhibitory adenylyl cyclase and that for phosphorylation of Gi alpha 2 were similar in cells challenged with phorbol myristic acid. These data argue for cross-regulation from the stimulatory protein kinase C to inhibitory adenylyl cyclase pathways at the level of Gi alpha 2 via protein phosphorylation.

Topics: Adenylyl Cyclases; Enkephalin, Leucine-2-Alanine; Enzyme Activation; Ethers, Cyclic; Glioma; GTP-Binding Proteins; Hybrid Cells; Naphthalenes; Neuroblastoma; Okadaic Acid; Phorbols; Phosphorylation; Polycyclic Compounds; Protein Kinase C; Tetradecanoylphorbol Acetate; Tumor Cells, Cultured

Cytoplasmic extracts from proliferating Neuro-2a cells contain a protein factor, ADR (activator of DNA replication) that induces DNA synthesis in isolated quiescent nuclei. Cytoplasmic extracts derived from quiescent-made Neuro-2a cells contain none or very little ADR activity, but this activity can be generated after a brief exposure of cytosolic extracts to a membrane-enriched fraction derived from exponentially growing Neuro-2a cells. ADR activity appears at the beginning of the S phase of the cell cycle. Moreover it appears to be a protease, because aprotinin inhibits ADR activity. ADR activity can be also inhibited by the protein kinase C inhibitors, 1-(5-isoquinoline-sulfonyl)-2- methylpiperazine (H7) and calphostin C.

Topics: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; Animals; Cell Cycle; Cell Division; Cricetinae; Cytosol; DNA Replication; Enzyme Induction; Isoquinolines; Mice; Naphthalenes; Neuroblastoma; Phosphorylation; Piperazines; Polycyclic Compounds; Protein Kinase C; Serine Endopeptidases; Tumor Cells, Cultured

We have studied the effect of protein kinase C inhibitors 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H7) and calphostin C on the cycle of Neuro-2a cells. Both compounds inhibited cell proliferation and DNA synthesis. Transition from G2 to M phase was not altered by these compounds. Calphostin C blocked the cells in G0/G1, while H7 did not at any specific point in the cell cycle. We also show that the antiproliferative effect induced by both inhibitors is reversible.

Topics: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; Animals; Cell Cycle; Cell Membrane Permeability; Cell Survival; DNA; Isoquinolines; Light; Naphthalenes; Neuroblastoma; Piperazines; Polycyclic Compounds; Protein Kinase C; Sulfonamides; Tumor Cells, Cultured

We have investigated the modulatory action of carbachol on intracellular cAMP levels in human neuroblastoma SH-SY5Y cells. Carbachol enhanced forskolin-stimulated cAMP levels in a dose-dependent manner (EC50 = 3 microM). The enhancing effect of carbachol was completely inhibited by pirenzepine and atropine. Pertussis toxin treatment of the cells partially affected the ability of carbachol. Furthermore, carbachol also enhanced the effect of vasoactive intestinal peptide (EC50 = 3 microM)-, adenosine- and prostaglandin E1-stimulated cAMP levels. The enhancing response of carbachol was sensitive to trifluoperazine but insensitive to calphostin C. These results suggest that the mechanism for carbachol-induced cAMP levels may act, at least in part, through the activation of calmodulin system in SH-SY5Y cells. Hence we describe for the first time a synergistic interaction between calmodulin- and cAMP-dependent signal transduction pathway mediated by carbachol in neuron-derived cell line.

Topics: Adenosine; Alprostadil; Atropine; Calmodulin; Carbachol; Cell Line; Colforsin; Cyclic AMP; Drug Synergism; Humans; Kinetics; Naphthalenes; Neuroblastoma; Pertussis Toxin; Polycyclic Compounds; Protein Kinase C; Trifluoperazine; Vasoactive Intestinal Peptide; Virulence Factors, Bordetella