Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0027819 (neuroblastoma)
 27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

SK-N-MC cells, derived from a human neuroblastoma, respond to endothelin (ET) peptides with an increase in the free intracellular calcium concentration. The response is biphasic, with the secondary plateau phase being abolished or reduced by removal of extracellular Ca2+ or by the presence of 100nM nitrendipine. Restoration of Ca2+ to the bathing solution in cells stimulated by ET-1 in the absence of Ca2+ caused the plateau to reappear. The order of potency of ET family peptides was ET-2 greater than or equal to sarafotoxin S6b greater than or equal to ET-1 much greater than ET-3, suggesting that ETA receptors mediate the response. Sarafotoxin S6c and the C-terminal hexapeptide endothelin (16-21) were inactive in these cells. [Ala1,3,11,15]ET-1, a linear analogue of ET-1 which has been suggested to be a selective ETB receptor agonist, was a weak competitive antagonist of the actions of ET-1 in these cells. However, BQ-123, recently introduced as a selective and competitive antagonist at ETA receptors, was a potent non-competitive antagonist of ET-1 giving a 50% reduction in the maximum response at 6nM.
 ...
PMID:BQ-123, cyclo(-D-Trp-D-Asp-Pro-D-Val-Leu), is a non-competitive antagonist of the actions of endothelin-1 in SK-N-MC human neuroblastoma cells. 156 52

1. Specific binding sites for synthetic endothelin (ET) isoforms were studied on intact cells of the SK-N-MC cell line, derived from a human neuroblastoma. 2. [125I]-ET-1 (2.5 x 10(-11) M) specifically bound to a single class of binding sites on these cells (Hill coefficient of 1.06 +/- 0.04, n = 3) with an apparent Kd of 1.4 +/- 0.3 x 10(-9) M and a Bmax of 3.1 +/- 1.0 pmol mg-1 protein. [125I]-ET-3 (2.5 x 10(-11) M), did not specifically bind to SK-N-MC cells. 3. The binding of [125I]-ET-1 was competitively inhibited by other ET isoforms, the order of potency being ET-1 greater than sarafotoxin S6b greater than ET-3. 4. Association of 1 nM [125I]-ET-1 at 37 degrees C reached apparent equilibrium at 60-80 min, with half-maximal binding being achieved at 12 min. 5. Dissociation was measured after both 10 min and 60 min of association with 64% and 30% respectively of specifically bound [125I]-ET-1 dissociating. The actual amounts of [125I]-ET-1 dissociated were similar in both cases. 6. Incubation of [125I]-ET-3 with SK-N-MC cells at 37 degrees C for 60 min did not result in significant degradation of this peptide. However, [125I]-ET-1 was broken down by incubation with SK-N-MC cells, the pattern of degradation of dissociable [125I]-ET-1 (and that found in the supernatant) being different from that of non-dissociable [125I]-ET-1. 7. ET-1 concentration-dependently induced an increase in total inositol phosphate accumulation in subconfluent (but not in confluent) cultures of SK-N-MC cells (EC50 = 6.43 +/- 1.9 x 1010M). ET-3 was without effect. 8. These results show that ET-1 specifically binds to SK-N-MC cells with the characteristics of an ETA receptor. Our earlier finding that adrenal chromaffin cells express an ETB receptor indicates the existence of multiple ET receptor types on neuronal cells.
 ...
PMID:Characterization of endothelin receptors on a human neuroblastoma cell line: evidence for the ETA subtype. 166 49

The mode of binding of [3H]BQ-123 (cyclo(-D-Trp-D-Asp-[prolyl-3,4 (n)-[3H]]Pro-D-Val-Leu)), an endothelin receptor antagonist radioligand, was evaluated in the human neuroblastoma cell line SK-N-MC at 37 degrees C. Scatchard analysis indicated the presence of a single class of [3H]BQ-123 binding sites with a high affinity of 3.2 nM. [3H]BQ-123 binding achieved steady state within 7 min and dissociated with a half-time of 1.4 min, while [125I] endothelin-1 binding barely reached a steady state even after 6 h and showed little dissociation. [3H]BQ-123 binding was sensitive to endothelin-1 and endothelin-2 (Ki values = 0.058 and 0.10 nM, respectively) and the endothelin ETA receptor-selective antagonist BQ-123 (Ki = 3.3 nM), while showing low affinity for endothelin-3 (Ki = 50 nM), the endothelin ETB receptor-selective agonist BQ-3020 (Ki = 970 nM) and other bioactive peptides. Thus, [3H]BQ-123 is a specific and reversible radioligand for endothelin ETA receptors. The rapid reversibility of [3H]BQ-123 binding should provide a tool for estimating the equilibrium inhibition constants (Ki values) of various compounds for endothelin ETA receptors.
 ...
PMID:[3H]BQ-123, a highly specific and reversible radioligand for the endothelin ETA receptor subtype. 776 60

We describe the characteristics of a potent and selective endothelin (ET) B-receptor antagonist, BQ-788 [N-cis-2,6-dimethylpiperidinocarbonyl-L-gamma-methylleucyl-D -1- methoxycarbonyltryptophanyl-D-norleucine]. In vitro, this compound potently and competitively inhibits 125I-labeled endothelin 1 (ET-1) binding to ETB receptors on human Girardi heart cells (IC50, 1.2 nM) but only poorly inhibits the binding to ETA receptors on human neuroblastoma cell line SK-N-MC cells (IC50, 1300 nM). In isolated rabbit pulmonary arteries, BQ-788 shows no agonist activity up to 10 microM and competitively antagonizes the vasoconstriction induced by an ETB-selective agonist, BQ-3020 (pA2, 8.4). In rat, an ETA-selective antagonist, BQ-123 (1 mg/kg, i.v.), does not affect transient depressor response to ET-1 (0.3 nmol/kg, i.v.) but potently inhibits following sustained pressor response; vice versa, BQ-788 (1 mg/kg, i.v.) abolishes the depressor response, resulting in a rapid onset of apparently enhanced pressor response. Thus, being a potent and selective ETB receptor antagonist, BQ-788 may be considered as a powerful tool for investigating the role of ET in physiological and pathological processes.
 ...
PMID:Biochemical and pharmacological profile of a potent and selective endothelin B-receptor antagonist, BQ-788. 819 52

BQ-123 (cyclo[D-Trp-D-Asp-Pro-D-Val-Leu]) is a competitive antagonist of the ETA receptor subtype for endothelins in aortic myocytes, and a non-competitive antagonist in human neuroblastoma cells. In the present study, using indo-1 loaded rat brain capillary endothelial cells, we demonstrate that BQ-123 acts either as a non-competitive antagonist of endothelin-1 action on [Ca2+]i depending on the experimental conditions used. A simple hypothesis to account for these results is that BQ-123 forms stable complexes with ETA receptors that are, however, less stable than the complexes formed by endothelin-1 and ETA receptors.
 ...
PMID:Competitive and non competitive interactions of BQ-123 with endothelin ETA receptors. 833 61

The endothelin (ET) peptides have been identified in the CNS, but there is a paucity of information on their physiological roles. NG108-15 cells, a clonal strain of a neuroblastoma x glioma hybrid cell line, have been widely used in neurobiological research since they retain certain differentiated properties of the non-transformed parental cells. It is known that NG108-15 cells respond to the ET peptides, but only limited information is available on the characterization of the ET receptors that mediate these effects. The present study was designed to identify the type(s) of ET receptors on NG108-15 cells in a proliferative state by competitive binding assays using [125I]ET-1 as the radiolabelled ligand and the receptor-selective ligands. ET-1, ET-3, BQ-123, sarafatoxin-6-c and [Ala1,3,11,15]ET-1. The results suggested the presence of conventional ETA and ETB receptor subtypes, with ETA in excess over ETB. These findings were consistent with the results of Northern analysis in that mRNAs encoding the ETA and ETB receptor subtypes were identified in NG108-15 cells, with a preponderance of ETA to ETB. Of considerable interest was the observation of other ET-binding components with much higher affinities than the conventional receptors. It remains to be demonstrated if these particular binding components are functional and represent differ gene products or arise from association of the conventional ETA and ETB receptor subtypes with themselves or other structures, e.g. proteins or lipids, of CNS origin.
 ...
PMID:Endothelin binding to NG108-15 cells: evidence for conventional ETA and ETB receptor subtypes and super-high affinity binding components. 899 27

The method described was developed to be applied in determination of selenium in biological matrices (plasma, urine and tissues) using ETA-AAS with Zeeman background correction. These matrices were obtained from non-fasting S.D. rats and Beagle dogs of both sexes in order to acquire data on the endogenous levels of selenium in these laboratory animals when fed with standard diets. For tissue digestion, a simple procedure using the strong organic base, Soluene 350, was adopted. Precision assays were carried out monitoring Se(IV) levels in spiked matrices (range from 25 to 200 ng) and obtaining relative standard deviations (RSD%) in the range from 3.2% to 14.5% (intra-day) and from 7.6% to 15.9% (inter-day). Accuracy assays gave relative errors (RE%) in the range from -6.5 to 4.2% (intra-day) and from -5.5% to 5.7% (inter-day). The validity of the method was checked on reference material (NBS SRM 1577 bovine liver) and the values obtained correlated with the certified ones. The detection limit assumed was 0.9 ng/ml, whereas the quantitation limit of selenium in matrices ranged from 2 to 5 ng/ml (or g), depending on the kind of sample.
 ...
PMID:Determination of selenium in plasma, urine and tissues, of standard diet-fed rats and dogs by ETA-atomic absorption spectroscopy with Zeeman background correction. 903 61

The endothelin (ET) peptides, ET-1, ET-2, and ET-3, as well as the ETA and ETB receptor subtypes, are known to occur in brain, but there is a dearth of information on the metabolism of these peptides by the central nervous system (CNS). In this study we have investigated the kinetics of ET-1 binding to and dissociation from the hybrid neuroblastoma x glioma cell line, NG108-15, which is known to contain functional ET receptors, and metabolism of bound ET-1. [125I]ET-1 was incubated with cells for various periods of time up to 6 h, and the nature of the radioactivity in the cell medium and lysate was analyzed by reverse phase high performance liquid chromatography (HPLC). It was found that NG108-15 cells are capable of degrading [125I]ET-1 to [125I]Tyr and several fragments of intermediate hydrophobicity; however, a portion of the cell-associated [125I]ET-1 was protected from degradation for several hours.
 ...
PMID:Metabolism of endothelin-1 by neuroblastoma x glioma hybrid (NG108-15) cells. 914 3

The mechanism underlying endothelin-1 (ET-1)-induced increases in intracellular Ca2+ concentrations in the human neuroblastoma cell-line SK-N-MC was investigated. ET-receptor agonists increased inositol phosphate (IP)-formation (assessed as accumulation of total [3H]-IPs in [3H]-myo-inositol prelabelled cells) and intracellular Ca2+ (assessed by the FURA-2 method) with an order of potency: ET-1 > sarafotoxin 6b (S6b)> ET-3 = S6c; the ETA-receptor antagonist BQ-123 inhibited both responses with apparent pKi-values of 8.3 and 8.6, respectively, while the ETB-receptor antagonist BQ-788 did not. Pretreatment of the cells with pertussis toxin (PTX, 500 ng ml(-1) overnight) reduced ET-1-induced Ca2+ increases by 46+/-5%, but rather enhanced ET-1-induced IP-formation. Chelation of extracellular Ca2+ by 5 mM EGTA did not affect ET-1-induced IP-formation. However, in the presence of 5 mM EGTA or SKF 96365, an inhibitor of receptor mediated Ca2+ influx (1.0-3.0 x 10(-5) M) ET-1-induced Ca2+ increases were inhibited in normal, but not in PTX-treated cells. [125I]-ET-1 binding studies as well as mRNA expression studies (by RT-PCR) detected only ETA-receptors whereas expression of ETB-receptor mRNA was marginal. ET-1 (10(-8) M) inhibited isoprenaline-evoked cyclic AMP increases; this was antagonized by BQ-123, not affected by BQ-788 and abolished by PTX-treatment. We conclude that SK-N-MC cells contain a homogeneous population of ETA-receptors that couple to IP-formation and inhibition of cyclic AMP formation. Stimulation of these ETA-receptors increases intracellular Ca2+ by at least two mechanisms: a PTX-insensitive IP-mediated Ca2+ mobilization from intracellular stores and a PTX-sensitive influx of extracellular Ca2+.
 ...
PMID:Mechanism of ET(A)-receptor stimulation-induced increases in intracellular Ca2+ in SK-N-MC cells. 986 48

Since the disialoganglioside GD2 is abundantly present on the surface of neuroblastoma cells, we constructed a new recombinant immunotoxin for possible clinical use in patients with neuroblastoma. A functional 14.18 scFv-phage was obtained by selection of an anti-GD2 hybridoma derived phage antibody mini-library on the neuroblastoma-derived, GD2-expressing cell line IMR5. By insertion into the bacterial expression vector pBM1.1 the selected scFv was fused to a deletion mutant of Pseudomonas exotoxin A (ETA'). Periplasmically expressed 14.18(scFv)-ETA' bound to the GD2 expressing cell line IMR5, but not to the GD2 negative Hodgkin-derived cell line L540Cy as documented by ELISA and flow cytometry. The recombinant immunotoxin (rIT) inhibited cell viability of IMR5 cells by 50% at concentrations (IC(50)) of 0.326 microg/ml. This recombinant immunotoxin will be further investigated in vivo for its value as a new immunotherapeutic agent for the treatment of patients with neuroblastoma.
 ...
PMID:An anti-GD2 single chain Fv selected by phage display and fused to Pseudomonas exotoxin A develops specific cytotoxic activity against neuroblastoma derived cell lines. 1160 31


1 2 Next >>