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

The isolation and hormonal regulation of two low molecular weight insulin-like growth factor binding proteins (IGFBPs) present in the conditioned medium (CM) of the rat neuroblastoma cell line B104 cells has been performed. IGFBPs were purified by ZnSO4 precipitation, insulin-like growth factor-I 1IGF-I) affinity chromatography, and reverse phase HPLC. Final isolation and N-terminal analysis was accomplished by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, electroblotting to polyvinylidene difluoride membranes, and sequencing of the bound proteins. Two IGFBPs, with apparent Mr of 28K and 24K were coisolated and sequenced. Both proteins had identical N-terminal sequences and appear to be two forms of IGFBP-4. Treatment of the IGFBPs with endoglycosidase-F caused a shift in the apparent Mr of the 28K IGFBP to 24K. However, there was no change in the apparent Mr of the 24K IGFBP. The data from this study suggest that the IGFBP-4 exists as both a glycosylated and nonglycosylated protein. Treatment of B104 cells with IGF-I increased the expression of both the 24K and 28K IGFBPs and also resulted in the appearance of IGFBP-3 and an unknown IGFBP at 29K. When added to subconfluent cells, IGF-I was also mitogenic in B104 cells. Similar to IGF-I, IGF-II treatment increased cell number and resulted in the appearance of IGFBP-3 and the 29K IGFBP. However, IGF-II treatment resulted in a significant decrease (approximately 50%) in the 24K IGFBP and also decreased the 28K IGFBP. This decrease in the expression of the 24K and 28K IGFBPs was dose-dependent and was blocked by addition of IGF-I to the cells. When an IGF-II receptor antibody was added to the cells it mimicked the effects of IGF-II on B104 cells, suggesting that the inhibitory effects of IGF-II are mediated through the type II IGF receptor. Although both IGF-I and IGF-II affected the amount of the 24K IGFBP in the CM, neither peptide affected the expression of the messenger RNA for the 24K IGFBP. In conclusion, we have isolated two IGFBPs from the CM of B104 cells. Both the 24K and 28K IGFBPs appear to be isoforms of the same protein, and sequence data suggest these proteins are two forms of IGFBP-4. IGF-I increases the expression of both of these IGFBPs, whereas IGF-II decreases their expression.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Differential effects of insulin-like growth factor (IGF)-I and IGF-II on the expression of IGF binding proteins (IGFBPs) in a rat neuroblastoma cell line: isolation and characterization of two forms of IGFBP-4. 170 57

Insulin-like growth factor (IGF)-binding proteins (BPs) bind IGF-I and IGF-II with high affinity and modify the activity of IGF peptides in a complex manner. We have characterized the affinities of IGFBP-1-4 for IGF-I and -II by employing 1) purified IGFBP preparations, 2) both [125I]IGF-I and [125I]IGF-II as radioligands, and 3) multiple IGF analogs designed to have altered affinities for IGFBPs. To this end, human (h) IGFBP-1, hIGFBP-2, and rat (r) IGFBP-4 have been purified to homogeneity from human amniotic fluid, human prostate epithelial cell culture, and B104 rat neuroblastoma cells; for human IGFBP-3, the glycosylated recombinant form (rec-hIGFBP-3), produced in Chinese hamster ovary cells, was employed. The IC50 values of IGF-I for hIGFBP-1, hIGFBP-2, rec-hIGFBP-3, rIGFBP-4, and human serum IGFBPs were 0.05 +/- 0.01, 5.0 +/- 0.01, 0.25 +/- 0.20, 0.6 +/- 0.4, and 0.1 +/- 0.01 ng/ml, respectively. While hIGFBP-1 and rIGFBP-4 had virtually equivalent affinities for IGF-I and IGF-II, hIGFBP-2 and rec-hIGFBP-3 demonstrated 2- to 5-fold higher affinities for IGF-II than for IGF-I. Studies with [Gln3,Ala4,Tyr15,Leu16]IGF-I and Des-(1-3)-IGF-I indicate that specific residues in the first 16 amino acids of the B domain of IGF-I appear to be critical for binding to all of the IGFBPs tested, but not to IGF receptors. However, severe modifications in the B domain disrupt binding affinity, not only for IGFBPs, but also for receptors (IGF-I/insulin hybrid and B-chain mutant). Interestingly, modifications in the A domain of IGF-I, which is believed to contain residues critical for binding to IGF-I and insulin receptors, show differential effects on binding affinity to BPs. [Thr49,Ser50,Ile51]IGF-I, which has normal affinity for the type I IGF receptor, shows at least a 500-fold decreased affinity for hIGFBP-1 and recombinant hIGFBP-3, in contrast to 50- to 100-fold reduced affinity for hIGFBP-2 and rIGFBP-4, and 5- to 10-fold reduced affinity for purified human serum IGFBP-3. More significantly, [1-27,Gly4,38-70]IGF-I shows a 30-fold decreased affinity for the type I IGF receptor and 10- and 2.5-fold reduced affinities for hIGFBP-1 and rec-hIGFBP-3, respectively, but no reduction in affinity for hIGFBP-2 or rIGFBP-4.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Characterization of the affinities of insulin-like growth factor (IGF)-binding proteins 1-4 for IGF-I, IGF-II, IGF-I/insulin hybrid, and IGF-I analogs. 767 79

Growth in neuroblastoma cells is regulated by insulin-like growth factors (IGFs) whose action is modulated by IGF binding proteins (IGFBPs). In this study, SK-N-SH neuroblastoma cells were shown to produce IGF-II, IGFBP-2, IGFBP-4 and small quantities of IGFBP-6. We have studied the effects of a natural morphogen, retinoic acid (RA), on growth and IGFBP expression in these cells. In all experiments, cells were cultured in serum-free medium and treated with 1 mumol/l RA for 12 h. Cell number increased by almost 50% during the first 24 h after the beginning of treatment. This stimulation was inhibited by 80% or more in the presence of the anti-type 1 IGF receptor antibody alpha-IR3 and anti-IGF-II antibody. The IGF-II concentrations in the culture media, measured after acidic gel filtration, increased about 1.5-fold and Northern blotting showed a concomitant increase in IGF-II mRNA levels. The mitogenic effect of RA therefore reflects its stimulation of IGF-II production. The availability of IGF-II to the cells may also be enhanced because of the proteolysis of IGFBP-2 to which it is bound. After this initial phase, proliferation ceased despite continued IGF-II production between 24 and 72 h. Both IGFBP-2 and IGFBP-4 production decreased, whereas that of IGFBP-6 increased. These changes appeared both in the protein quantities and in their mRNAs. Insulin-like growth factor binding protein 6 has a strong affinity for IGF-II, 5-10 times that of IGFBP-2 and at least 10 times that of the type I IGF receptor, and the arrested proliferation may result, at least in part, from sequestration by IGFBP-6 of the IGF-II secreted.
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PMID:Modulation by retinoic acid of insulin-like growth factor (IGF) and IGF binding protein expression in human SK-N-SH neuroblastoma cells. 864 Mar

Insulin-like growth factor (IGF) binding proteins (IGFBPs) modulate IGF action at cellular level through inhibition or, alternatively, potentiation, where their limited proteolysis is a contributory mechanism. Under basal conditions, neuroblastoma cells secrete IGFs (essentially IGF-II), IGFBPs (IGFBP-4 and predominantly IGFBP-2 that is partially proteolysed), and proteases, including tissue-type plasminogen (PLG) activator, whose activity is inhibited by PLG activator inhibitor-1. Neuroblastoma cells were used to investigate the influence of the plasmin system, transforming growth factor-beta retinoic acid on cell growth and the IGF system. In cells treated with 5 micrograms/ml PLG, proliferation was stimulated, an effect that was inhibited in the presence of either alpha IR-3 (which blocks the type 1 IGF receptor) or anti-IGF-II antibodies. There was a parallel increase in IGFBP-2 proteolysis, which resulted in a 5-fold loss of affinity for IGF-II. In the presence of 1 ng/ml transforming growth factor-beta, PLG-induced mitogenesis and IGFBP-2 proteolysis were reduced, and Northern blot analysis revealed increased PLG activator inhibitor-1 mRNA. Conversely, with 2 microM retinoic acid, the mitogenic effect of PLG, IGFBP-2 proteolysis, and tissue-type PLG activator mRNAs were increased. Therefore, IGF-II mediates autocrine proliferation in neuroblastoma cells under the control of IGFBPs secreted by the cells, its bioavailability being enhanced as a result of plasmin-induced IGFBP-2 proteolysis.
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PMID:Role of insulin-like growth factor binding protein-2 and its limited proteolysis in neuroblastoma cell proliferation: modulation by transforming growth factor-beta and retinoic acid. 900 3

The IGF system is involved in the growth and differentiation of neuroblastoma cells, but the precise roles played by the IGF-binding proteins (IGFBPs) remain unknown. We have examined the expression and functions of IGFBPs produced by the neuroblastoma cell line, SH-SY5Y, in the presence of: insulin, IGF-I, IGF-II, des(1-3)IGF-I (an IGF-I analogue with weak affinity for IGFBPs), acidic fibroblast growth factor, basic fibroblast growth factor, or nerve growth factor. Under basal conditions, SH-SY5Y cells in serum-free medium secreted IGF-II, and traces of IGF-I, IGFBP-2 and IGFBP-4. After 24 h of culture, comparative mitogenic potencies were: des(1-3)IGF-I > IGF-I > IGF-II > insulin. After 48 h, when IGFBP-2 and IGFBP-4 concentrations in the culture media had increased, des(1-3)IGF-I remained the most active, but the activity of insulin now equalled or exceeded that of IGF-I and IGF-II. This suggests a negative feedback mechanism involving partial sequestration of IGF-I and IGF-II by IGFBP-2 and IGFBP-4. At high cell density and with high concentrations of IGF-I, des(1-3)IGF-I (40 ng/ml) or IGF-II (80 ng/ml), the mitogenic activities of the IGFs diminished concomitantly with the appearance in the culture medium of an additional IGFBP identified as IGFBP-6, whose production depended on activation of the type 1 IGF receptor. These findings suggest that IGFBP-6 contributes as an autocrine inhibitor in the regulation of growth by the IGF system in these neuroblastoma cells.
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PMID:IGF-binding protein-6 is involved in growth inhibition in SH-SY5Y human neuroblastoma cells: its production is both IGF- and cell density-dependent. 907 79

Insulin-like growth factors (IGF-I and IGF-II) stimulate proliferation and differentiation in many cell types. In biological fluids, they associate non-covalently with high-affinity binding proteins (IGFBPs) which control their bioavailability and modulate their action. We previously demonstrated that IGFBP-2, -4 and -6 are intimately involved in the growth of cells derived from human neuroblastomas. Here, we have investigated the effects of retinoic acid (RA), which induces differentiation in these cells, on the expression of IGFBPs secreted by SK-N-SH neuroblastoma cells. Analysis of transcriptional activity of the IGFBP-2, -4 and -6 genes in isolated nuclei (run-on experiments) showed that RA increased the transcriptional activity of the IGFBP-6 gene, reduced that of the IGFBP-4 gene and had no effect on that of the IGFBP-2 gene. Northern blot analysis following treatment with actinomycin D showed that RA increased the stability of IGFBP-6 mRNA by a factor of 2.6, decreased that of IGFBP-2 mRNA by a factor of 2.3 and failed to affect IGFBP-4 mRNA. Treatment of cells with cycloheximide indicated the involvement of labile proteins in the stabilization of these mRNAs the expression of which could be under the control of RA. The transcriptional and/or post-transcriptional mechanisms by which RA regulates each of the IGFBPs produced by SK-N-SH cells are therefore different. Such regulation may also reflect the state of differentiation of the neuroblastoma cells. With RA-induced differentiation, IGFBP-6 is strongly stimulated, whereas IGFBP-2 and IGFBP-4 are severely depressed, which would suggest that each IGFBP plays a specific role. Moreover, this regulation seems tissue-specific because it is different in other cell types.
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PMID:Retinoic acid stimulates IGF binding protein (IGFBP)-6 and depresses IGFBP-2 and IGFBP-4 in SK-N-SH human neuroblastoma cells. 979 62

Insulin-like growth factors I and II (IGF-I and IGF-II) stimulate proliferation and differentiation in many cell types, including cell lines derived from human neuroblastomas. Their effects are mediated via the IGF-I receptor (IGF-IR) that is essential for growth in these cells. Amplification of the N-myc oncogene is a marker for poor prognosis in neuroblastoma development, and it therefore seemed of interest to analyze the relationships that may exist between IGF-IR and N-myc. N-myc-deficient SK-N-SH neuroblastoma cells were used as an experimental model. After stable transfection with N-myc cDNA, Northern blotting revealed a marked increased in IGF-IR, IGF-II, IGF-binding protein (IGFBP)-2, and IGFBP-4 mRNA levels, whereas IGFBP-6 mRNA levels were clearly diminished. Western immunoblot analysis also demonstrated increased intact IGFBP-2 but decreased IGFBP-6 in the presence of N-myc oncogene. Parallel binding experiments using IGF-I missing the first 3 amino acids revealed a 47% increase in binding sites for IGF-I and an increase of at least 335% in DNA synthesis, as measured by labeled thymidine incorporation into DNA. s.c. injection of these cells into nude mice provoked xenograft development in 50-100% of cases (depending on the series of experiments). Control cells, in contrast, were not tumorigenic. In cells transfected with bp -420/+60 of the human IGF-IR promoter controlling expression of the luciferase reporter gene, promoter activity was stimulated by a factor of 3.8 +/- 0.6 (n = 6) in the presence of N-myc oncogene. This suggests transcriptional regulation of IGF-IR expression by N-myc. IGF-IR activity and N-myc amplification are two events that to date have been identified as independently instrumental in the etiology of human neuroblastoma. Our results provide the first evidence of a direct link between them and demonstrate the effects of the oncogene on components of the IGF system in neuroblastoma cell growth in vitro and in vivo.
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PMID:N-myc regulation of type I insulin-like growth factor receptor in a human neuroblastoma cell line. 1038 52

Previous work has shown that neuroblastoma cells secrete IGFBP-2, -4 and -6 and that expression of these proteins is regulated by retinoic acid (at-RA) which promotes differentiation in these cells. Other agents also induce differentiation of neuroblastoma cells: these include the 9- cis and 13- cis isomers of at-RA, 1,25 dihydroxy- vitamin D3 (VD3), triidothyronine (T3) and 12-O-tetradecanoyl phorbol 13-acetate (TPA). Nine- cis and 13- cis isomers of at-RA increased IGFBP-6 expression, but decreased IGFBP-2 and IGFBP-4. VD3 stimulated IGFBP-6 and IGFBP-2 expression, whereas T3 inhibited IGFBP-6 expression without affecting IGFBP-2. TPA markedly enhanced expression of all three IGFBPs produced by SK-N-SH cells. Since IGFBP-6 secretion is associated with the arrest of proliferation in neuroblastoma cells and is regulated by the combined actions of differentiation factors, we subcloned the proximal promoter of human IGFBP-6 (nt -766/+1) into a pCAT expression vector so as to examine modulation of its transcriptional activity. VD3 and TPA were capable of stimulating promoter activity, T3 depressed it and at-RA and its 9- cis and 13- cis isomers had no effect. These results confirm the high sensitivity of IGFBP-6 expression to these differentiation agents, essentially at transcriptional level.
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PMID:Multi-hormonal regulation of IGFBP-6 expression in human neuroblastoma cells. 1116 66

With a view to investigating the implication of IGF-binding protein-6 (IGFBP-6) in the growth of neuroblastomas, nude mice were injected with IGFBP-6-expressing or control IGR-N-91 human neuroblastoma cells and the resulting xenografts examined. Expression of IGFBP-3, IGFBP-4 and type 1 and type 2 IGF receptor messengers was similar in control tumours and equal-sized IGFBP-6-expressing tumours that had developed. IGF-II was more strongly expressed in control tumours, and IGFBP-6-expressing tumours contained less IGFBP-2 than controls. In both populations, there was a significant positive correlation between IGF-II and IGFBP-2 expression. In small IGFBP-6-expressing xenografts where tumour development had apparently been arrested, haematoxylin--eosin and TUNEL staining revealed numerous apoptotic cells. In situ hybridization indicated homogeneous distribution of the IGFBP-6 signal in test tumours. In cell culture, IGFBP-6-expressing cells expressed similar amounts of IGFBP-2, IGF-II and N-myc mRNAs as control cells; but media conditioned by IGFBP-6-expressing cells contained less intact IGFBP-2 protein, with no increase in its proteolytic fragment. In media treated with plasminogen, in which IGFBP-2 was proteolysed, IGFBP-6 was increased. With its especially strong affinity for IGF-II and its resistance to proteolysis, IGFBP-6 would act by sequestering IGF-II, hence inhibiting its mitogenic and anti-apoptotic effects. In excess, IGFBP-6 would displace IGF-II from IGFBP-2 whose potentiation of IGF-II action would cease and whose susceptibility to degradation would be increased. This study therefore shows that IGFBP-6 plays a role in neuroblastoma cell growth in vivo and in vitro and that stable overexpression of IGFBP-6 leads to alteration of the initial balance between the IGFBPs.
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PMID:The IGF system in neuroblastoma xenografts: focus on IGF-binding protein-6. 1187 95