vasoactive-intestinal-peptide and Brain-Neoplasms

Parkinson's disease (PD) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) toxicity are both associated with dopaminergic neuron death in the substantia nigra. Although a variety of evidence has shown that degenerative cells have apoptotic features, the role of apoptosis in disease pathology remains controversial. The 1-methyl-4-phenylpyridinium ion (MPP(+)), a metabolite of MPTP, was recently shown to alter the expression of proteins involved in translational control. The initiation step of translational control is regulated by a cascade of phosphorylation affecting proteins of the antiapoptotic way controlled by mammalian target of rapamycin (mTOR) and of the proapoptotic way controlled by double-stranded RNA protein-dependent kinase (PKR). A study showed that MPP(+) induced an increase in eIF2alpha phosphorylation, leading to inhibition of protein synthesis.. (1) to assess the effects of MPP(+) toxicity on molecular factors of PKR and mTOR signaling pathways in murine neuroblastoma cells, and (2) to examine the ability of VIP and PACAP peptides to counteract the MPP(+) toxicity. Our findings showed that MPP(+) induced phosphorylation of eIF2alpha and significantly reduced the expression of phosphorylated mTOR, p70S6K, eIF4E, and 4E-BP1, suggesting its toxicity in controlling protein synthesis. Furthermore, the VIP peptide had no effect on either the PKR or the mTOR signaling pathway. On the contrary, the PACAP 27 neuropeptide prevented MPP(+)-induced eIF2alpha phosphorylation and blocked MPP(+) toxicity in molecular factors of the mTOR pathway. And last, PACAP 27 seemed to protect Neuro-2a cells from the apoptotic process as assessed by the decreased nuclear condensation after DAPI staining. These results could open new paths of research of PACAP in PD.

Topics: Animals; Blotting, Western; Brain Neoplasms; Caspase 3; Cell Line, Tumor; Fluorescent Dyes; Indoles; Mice; MPTP Poisoning; Neuroblastoma; Neuropeptides; Neuroprotective Agents; Phosphorylation; Pituitary Adenylate Cyclase-Activating Polypeptide; Protein Biosynthesis; Protein Kinases; Signal Transduction; TOR Serine-Threonine Kinases; Vasoactive Intestinal Peptide

The growth rate of numerous cancer cell lines is regulated in part by actions of neuropeptides of the vasoactive intestinal peptide (VIP) family, which also includes pituitary adenylate cyclase-activating peptide (PACAP), glucagon, and peptide histidine/isoleucine (PHI). The aim of this work was to investigate the effect of these peptides on the growth of the rat glioblastoma cell line C6 in vitro. We also sought to determine which binding sites were correlated with the effects observed. Proliferation studies performed by means of a CyQuant trade mark assay showed that VIP and PACAP strongly stimulated C6 cell proliferation at most of the concentrations tested, whereas PHI increased cell proliferation only when associated with VIP. Two growth hormone-releasing factor (GRF) derivatives and the VIP antagonist hybrid peptide neurotensin-VIP were able to inhibit VIP-induced cell growth stimulation, even at very low concentrations. Binding experiments carried out on intact cultured C6 cells, using 125I-labeled VIP and PACAP as tracers, revealed that the effects of the peptides on cell growth were correlated with the expression on C6 cells of polyvalent high-affinity VIP-PACAP binding sites and of a second subtype corresponding to very high-affinity VIP-selective binding species. The latter subtype, which interacted poorly with PACAP with a 10,000-fold lower affinity than VIP, might mediate the antagonist effects of neurotensin- VIP and of both GRF derivatives on VIP-induced cell growth stimulation.

Topics: Animals; Antineoplastic Agents; Binding Sites; Binding, Competitive; Brain Neoplasms; Cell Division; Cell Line, Tumor; Cell Transformation, Neoplastic; Dose-Response Relationship, Drug; Drug Synergism; Glioblastoma; Growth Hormone-Releasing Hormone; Neuropeptides; Neurotensin; Peptide PHI; Pituitary Adenylate Cyclase-Activating Polypeptide; Rats; Receptors, Cell Surface; Vasoactive Intestinal Peptide

Topics: Bombesin; Brain Neoplasms; Child; Gastrin-Releasing Peptide; Humans; Neoplasms, Nerve Tissue; Neuroectodermal Tumors; Neuropeptide Y; Neuropeptides; Neurotensin; Radioimmunoassay; Somatostatin; Vasoactive Intestinal Peptide

The effects of carbamylcholine (CCh) on the gene expression of the neuropeptide vasoactive intestinal polypeptide (VIP) were studied using two human neuroblastoma cell lines. NB-1 and BE(2)M17. CCh caused a fast increase in VIP mRNA level in both cell lines which was followed by an increase in VIP immunoreactivity. The time-course of the induction of both mRNA and peptide differed, however, between the two cell lines. No morphological changes of the cells were observed during 6 days of stimulation. The effect was mediated by the muscarinic class of acetylcholine receptors, since it could be totally abolished by atropine. Since CCh caused an accumulation of inositol-1,4,5-triphosphate, it is likely that muscarinic receptor subtype M1, M3 or M5 is involved. Experiments with the translational inhibitor, cycloheximide, showed that CCh mediated a direct effect on the VIP gene expression. By combining gel permeation chromatography with radiommunoassays using antisera specific for the various VIP-precursor products, immunoreactive peaks eluting as the synthetic peptides were found in both cell lines. In addition, earlier eluting peaks which could represent partially processed or extended VIP forms were found. After CCh induction the concentration of all prepro VIP-derived products increased, and there was a tendency towards a shift to more fully processed VIP. The findings give new evidence for a direct regulation of VIP gene expression in human neuronal cells by cholinergic agents.

Topics: Brain Neoplasms; Carbachol; Cycloheximide; Gene Expression Regulation, Neoplastic; Humans; Inositol 1,4,5-Trisphosphate; Neuroblastoma; Neuropeptides; Parasympathetic Nervous System; Parasympathomimetics; Protein Synthesis Inhibitors; Radioimmunoassay; RNA, Messenger; Tumor Cells, Cultured; Vasoactive Intestinal Peptide

Glia cell line-derived neurotrophic factor (GDNF), a recently cloned member of the transforming growth factor-beta (TGF-beta) superfamily, has been implicated in the survival, morphological and functional differentiation of midbrain dopaminergic neurons and motoneurons in vitro and in vivo. The factor may thus have utility in the treatment of various human neurodegenerative disorders. Mechanisms regulating expression of GDNF in normal and diseased brain as a possible means to increase the local availability of GDNF are only beginning to be explored. We have established and employed a competitive reverse transcriptase-polymerase chain reaction (RT-PCR) to study and compare levels of expression of GDNF mRNA in several cell types and to investigate its regulation. GDNF expression was clearly evident in primary cultured astrocytes, the glioma B49 and C6 cell, but less pronounced in the Schwannoma RN22 cell lines. Little or no signal could be observed in neuroblastoma cell lines (IMR32, LAN-1) or the pheochromocytoma cell line PC12, emphasizing the glial character of this factor. Using the C6 cell line we found that fibroblast growth factor-2 (FGF-2; bFGF) can increase GDNF mRNA levels, whereas FGF-1, platelet-derived growth factor (PDGF), and vasoactive intestinal polypeptide (VIP) are apparently ineffective. Several other factors (forskolin, kainic acid, triiodothyronine dexamethasone, GDNF, TGF-beta 1, and interleukin-6) appear to have slightly negative effects on GDNF mRNA levels at the concentrations tested. To further explore the relationship between FGF-2 and GDNF, we also addressed the question whether GDNF, like FGF-2, may have an effect on C6 cell proliferation. We conclude that (1) glial and glial tumor cells, rather than neuronal cell lines, express GDNF, (2) that FGF-2 has a prominent inductive effect on GDNF expression and (3) that GDNF stimulates C6 cell proliferation. Finally, these data suggest that neurotrophic actions of FGF-2 in mixed glial-neuronal cell cultures might be mediated in part by GDNF.

Topics: Animals; Astrocytes; Brain Neoplasms; Cell Division; Colforsin; Dexamethasone; Fibroblast Growth Factor 1; Fibroblast Growth Factor 2; Gene Expression Regulation, Neoplastic; Glial Cell Line-Derived Neurotrophic Factor; Glioma; Humans; Interleukin-6; Kainic Acid; Neoplasm Proteins; Nerve Growth Factors; Nerve Tissue Proteins; Neuroblastoma; Neurons; Organ Specificity; Pheochromocytoma; Platelet-Derived Growth Factor; Polymerase Chain Reaction; Rats; Recombinant Proteins; RNA, Messenger; RNA, Neoplasm; Triiodothyronine; Tumor Cells, Cultured; Vasoactive Intestinal Peptide

Functional VIP/PACAP receptors were identified in the human glioblastoma cell line T98G, based on the relative potency of VIP, PACAP and PACAP-38 to stimulate adenylate cyclase activity. Analysis of the T98G cells mRNA by reverse transcription followed by a polymerase chain reaction (RT-PCR) demonstrated the expression of the mRNA coding for the VIP2 receptor subclass only. VIP, PACAP-27 and PACAP-38 were potent and efficIent inhibitors of cell proliferation, assessed by the colorimetric MTT assay. VIP, PACAP-27 and PACAP-38 also reduced the incorporation of 3H-thymidine in T98G cells, but did not significantly alter the percentage of cells present at each stage of the cell cycle. Thus, VIP and PACAP, probably acting through a VIP2 receptor subtype, decreased cell proliferation.

Topics: Adenylyl Cyclases; Brain Neoplasms; Cell Cycle; Cell Division; DNA Replication; DNA, Neoplasm; Enzyme Activation; Glioblastoma; Growth Inhibitors; Humans; Neoplasm Proteins; Neuropeptides; Pituitary Adenylate Cyclase-Activating Polypeptide; Polymerase Chain Reaction; Receptors, Vasoactive Intestinal Peptide; Receptors, Vasoactive Intestinal Peptide, Type II; RNA, Messenger; Tumor Cells, Cultured; Vasoactive Intestinal Peptide

Concentrations of seven neuropeptides have been determined in 69 human neurological tumours. The majority of tumours were intrinsic to the central nervous system, being astrocytomas. In general, within the the better differentiated tumours (Grade I/II astrocytomas) higher concentrations of five neuropeptides (neuropeptide Y, somatostatin, substance P, vasoactive intestinal peptide and cholecystokinin) were measured in comparison to the poorly differentiated tumours. Of the metastatic tumours, five were derived from oat cell carcinoma of the bronchus. Very high concentrations of bombesin were identified in these metastases.

Topics: Astrocytoma; Bombesin; Brain Neoplasms; Humans; Meningeal Neoplasms; Nerve Tissue Proteins; Neuropeptide Y; Substance P; Vasoactive Intestinal Peptide

Topics: Brain Neoplasms; Calcitonin; Cholesterol; Diarrhea; Endocrine Glands; Gastrins; Gastrointestinal Hormones; Histamine Release; Humans; Hypercalcemia; Neoplasms; Nutrition Disorders; Pellagra; Peptides; Serum Albumin; Thyroid Hormones; Vasoactive Intestinal Peptide; Zollinger-Ellison Syndrome