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)

Choline acetyltransferase (ChAT), the biosynthetic enzyme for acetylcholine metabolism, is expressed in a human cholinergic neuroblastoma cell line; MC-IXC. We demonstrate that ChAT activity is regulated in this cell line by cell density. It is believed that the mechanism of stimulation of enzyme activity involves cellular contact, as medium conditioned by cells of high density failed to mimic the effect of density alone, and trypsinization reversed this effect. Density did not increase acetylcholinesterase activity, another marker for the cholinergic phenotype, in MC-IXC cultures, demonstrating the independent regulation of these two cholinergic enzymes. Since increased density slows the rate of cell division, we used a DNA synthesis inhibitor to uncouple DNA replication from cell density. This had no effect on the specific activity of ChAT, suggesting that a cell-cell contact was the mediating factor. Other neuroblastoma cell lines were tested, and only cell lines which already contain ChAT activity were sensitive to its regulation by cell-cell contact, suggesting that cell-cell contact is permissive rather than instructive in this process. The effect of cell passage on ChAT activity is also discussed.
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PMID:Regulation of choline acetyltransferase activity by cell density in a cultured human neuroblastoma cell line. 246 20

Treatment of the human neuroblastoma cell line SY5Y with nerve growth factor (NGF) induces terminal neuronal differentiation of a subpopulation of cells which can be selected by treatment with a DNA synthesis inhibitor. We have examined the interactions of naive (untreated) and NGF-differentiated SY5Y cells with laminin, and identified integrin receptors that mediate laminin-induced process outgrowth. Differentiated cells displayed a greater capacity for process extension, which correlated with increased expression of integrin laminin receptors. Both naive and differentiated cells expressed integrins alpha 1/beta 1, alpha 2/beta 1, and alpha 3/beta 1 but the differentiated population expressed about 5-fold higher levels of alpha 1/beta 1 and about 2-fold more alpha 2/beta 1 and alpha 3/beta 1 on their surface. Function blocking monoclonal antibodies were used to identify integrin receptors mediating process outgrowth. The anti-alpha 1 monoclonal antibody SR84 was shown to block alpha 1 function and inhibit process outgrowth on laminin. Despite the presence of multiple integrins which have been shown to bind laminin in other cell types, alpha 1/beta 1 mediated the majority of process outgrowth in both naive and differentiated cells, with a minor role played by alpha 3/beta 1. These data indicate that alpha 1/beta 1 function is required for process outgrowth on laminin by SY5Y cells and suggest that increased expression may be a crucial aspect of neuronal differentiation.
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PMID:Functional identification of integrin laminin receptors that mediate process outgrowth by human SY5Y neuroblastoma cells. 802 71

We have identified specific iron (Fe) chelators of the pyridoxal isonicotinoyl hydrazone (PIH) class that are far more effective ligands than desferrioxamine (DFO; Richardson et al, Blood 86:4295, 1995; Richardson and Milnes, Blood 89:3025, 1997). In the present study, we have compared the effect of DFO and one of the most active chelators (2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone; 311) on molecular targets involved in proliferation. This was performed to further understand the mechanisms involved in the antitumor activity of Fe chelators. Ligand 311 was far more active than DFO at increasing Fe release from SK-N-MC neuroepithelioma and BE-2 neuroblastoma cells and preventing Fe uptake from transferrin. Like DFO, 311 increased the RNA-binding activity of the iron-regulatory proteins (IRPs). However, despite the far greater Fe chelation efficacy of 311 compared with DFO, a similar increase in IRP-RNA binding activity occurred after 2 to 4 hours of incubation with either chelator, and the binding activity was not inhibited by cycloheximide. These results suggest that, irrespective of the Fe chelation efficacy of a ligand, an increase IRP-RNA binding activity occurred via a time-dependent step that did not require protein synthesis. Further studies examined the effect of 311 and DFO on the expression of p53-transactivated genes that are crucial for cell cycle control and DNA repair, namely WAF1, GADD45, and mdm-2. Incubation of 3 different cell lines with DFO or 311 caused a pronounced concentration- and time-dependent increase in the expression of WAF1 and GADD45 mRNA, but not mdm-2 mRNA. In accordance with the distinct differences in Fe chelation efficacy and antiproliferative activity of DFO and 311, much higher concentrations of DFO (150 micromol/L) than 311 (2.5 to 5 micromol/L) were required to markedly increase GADD45 and WAF1 mRNA levels. The increase in GADD45 and WAF1 mRNA expression was seen only after 20 hours of incubation with the chelators and was reversible after removal of the ligands. In contrast to the chelators, the Fe(III) complexes of DFO and 311 had no effect on increasing GADD45 and WAF1 mRNA levels, suggesting that Fe chelation was required. Finally, the increase in GADD45 and WAF1 mRNAs appeared to occur by a p53-independent pathway in SK-N-MC and K562 cells, because these cell lines lack functional p53. Our results suggest that GADD45 and WAF1 may play important roles in the cell cycle arrest observed after exposure to these chelators.
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PMID:The potential of iron chelators of the pyridoxal isonicotinoyl hydrazone class as effective antiproliferative agents III: the effect of the ligands on molecular targets involved in proliferation. 1039 46

The tumour suppressor p53 and the glucocorticoid receptor (GR) respond to different types of stress. We found that dexamethasone-activated endogenous and exogenous GR inhibit p53-dependent functions, including transactivation, up- (Bax and p21(WAF1/CIP1)) and down- (Bcl2) regulation of endogenous genes, cell cycle arrest and apoptosis. GR forms a complex with p53 in vivo, resulting in cytoplasmic sequestration of both p53 and GR. In neuroblastoma (NB) cells, cytoplasmic retention and inactivation of wild-type p53 involves GR. p53 and GR form a complex that is dissociated by GR antagonists, resulting in accumulation of p53 in the nucleus, activation of p53-responsive genes, growth arrest and apoptosis. These results suggest that molecules that efficiently disrupt GR-p53 interactions would have a therapeutic potential for the treatment of neuroblastoma and perhaps other diseases in which p53 is sequestered by GR.
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PMID:Negative cross-talk between p53 and the glucocorticoid receptor and its role in neuroblastoma cells. 1108 Jan 52

Neuroblastoma (NB) cells reportedly accumulate wild-type p53 exclusively in the cytoplasm. However, immunofluorescence assays with five different antibodies showed that p53 accumulates in the nucleus of up to 10% of NB cells. PAb1801 detected cytoplasmic 'punctate structures' which were also found in p53-null cells, rendering this antibody unsuitable for p53 detection. A comparison of DO-1 and PAb1801 staining in NB tissue sections confirmed the results obtained with NB cells. Nuclear accumulation of p53 was induced in NB cells using substances which disturb p53's tertiary structure at its zinc finger motif, or by treatment with mitomycin C. Constitutive nuclear accumulation was observed in an SK-N-SH variant, AW-1, which has a point mutation in p53 at Cys176>Ser, disturbing the same motif. Even though p53 showed DNA-binding capability after mitomycin C treatment of NB cells, the target gene products MDM2 and p21(WAF1,CIP1,SDI1) were not synthesized and no p53 transactivating activity measured in a reporter gene assay. Therefore we suggest that p53 in NB cells might be predominantly in a conformation refractory to integration into the transcriptional complex, resulting in at least partial transcriptional inactivity, hyperactive nuclear export and resistance to degradation by exogenously expressed MDM2.
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PMID:Evidence that wild-type p53 in neuroblastoma cells is in a conformation refractory to integration into the transcriptional complex. 1131 75

This study investigated the hypothesis that p53 accumulation in neuroblastoma, in the absence of mutation, is associated with functional inactivation, which interferes with downstream mediators of p53 function. To test this hypothesis, p53 expression, location, and functional integrity was examined in neuroblastoma by irradiating 6 neuroblastoma cell lines and studying the effects on p53 transcriptional function, cell cycle arrest, and induction of apoptosis, together with the transcriptional function of p53 after irradiation in three ex vivo primary, untreated neuroblastoma tumors. p53 sequencing showed five neuroblastoma cell lines, two of which were MYCN-amplified, and that all of the tumors were wild-type for p53. p53 was found to be predominantly nuclear before and after irradiation and to up-regulate the p53 responsive genes WAF1 and MDM2 in wild-type p53 cell lines and a poorly-differentiated neuroblastoma, but not a differentiating neuroblastoma or the ganglioneuroblastoma part of a nodular ganglioneuroblastoma in short term culture. This suggests intact p53 transcriptional activity in proliferating neuroblastoma. Irradiation of wild-type p53 neuroblastoma cell lines led to G(1) cell cycle arrest in cell lines without MYCN amplification, but not in those with MYCN amplification, despite induction of WAF1. This suggests MYCN amplification may alter downstream mediators of p53 function in neuroblastoma.
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PMID:p53 cellular localization and function in neuroblastoma: evidence for defective G(1) arrest despite WAF1 induction in MYCN-amplified cells. 1139 84

Previous reports raised question as to whether 8-chloro-cyclic adenosine 3,5-monophosphate (8-Cl-cAMP) is a prodrug for its metabolite, 8-Cl-adenosine which exerts growth inhibition in a broad spectrum of cancer cells. The present study was carried out to clarify overall cellular affects of 8-Cl-cAMP and 8-Cl-adenosine on SK-N-DZ human neuroblastoma cells by systematically characterizing gene expression using radioactive human cDNA microarray. Microarray was prepared with PCR-amplified cDNA of 2,304 known genes spotted on nylon membranes, employing (33)P-labeled cDNAs of SK-N-DZ cells as a probe. The expression levels of approximately 100 cDNAs, representing about 8% of the total DNA elements on the array, were altered in 8-Cl-adenosine- or 8-Cl-cAMP-treated cells, respectively. The genome-wide expression of the two samples exhibited partial overlaps; different sets of up-regulated genes but the same set of down-regulated genes. 8-Cl-adenosine treatment up-regulated genes involved in differentiation and development (LIM protein, connexin 26, neogenin, neurofilament triplet L protein and p21(WAF1/CIP1)) and immune response such as natural killer cells protein 4, and down-regulated ones involved in proliferation and transformation (transforming growth factor-beta, DYRK2, urokinase-type plasminogen activator and proteins involved in transcription and translation) which were in close parallel with those by 8-Cl-cAMP. Our results indicated that the two drugs shared common genomic pathways for the down-regulation of certain genes, but used distinct pathways for the up-regulation of different gene clusters. Based on the findings, we suggest that the anti-cancer activity of 8-Cl-cAMP results at least in part through 8-Cl-adenosine. Thus, the systematic use of DNA arrays can provide insight into the dynamic cellular pathways involved in anticancer activities of chemotherapeutics.
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PMID:Genome-wide expression profiling of 8-chloroadenosine- and 8-chloro-cAMP-treated human neuroblastoma cells using radioactive human cDNA microarray. 1221 10

Iron (Fe) is an obligate requirement for life and it is well known that Fe depletion leads to G(1)/S arrest and apoptosis. These facts, together with studies showing that Fe chelators can inhibit the growth of aggressive tumours such as neuroblastoma, suggest that Fe-deprivation may be an important therapeutic strategy. To optimise the anti-proliferative effects of Fe chelators, the role of Fe in cell cycle control requires intense investigation. For many years, Fe chelators were known to prevent the activity of the R2 subunit of ribonucleotide reductase (RR) that catalyzes the conversion of ribonucleotides into deoxyribonucleotides (dNTPs) for DNA synthesis. In addition, Fe depletion may also inhibit the newly identified p53-inducible form of this molecule called p53R2. This protein has the same Fe-binding sites as found in R2, and its activity is thought to supply dNTPs for the critical process of DNA repair. Iron chelation also causes hypophosphorylation of the retinoblastoma protein (pRb) and decreases the expression of cyclins A, B and D, which are vital for cell cycle progression. Other regulatory molecules whose expression is affected by Fe depletion include p53 and hypoxia inducible factor-1alpha (HIF-1alpha). The levels of p53 increase following Fe chelation via the ability of HIF-1alpha to bind and stabilize p53. The activity of HIF-1alpha is controlled by an Fe-dependent enzyme known as HIF-alpha prolyl hydroxylase (PH). Chelation of Fe from this enzyme inhibits its activity, leading to stabilization of HIF-1alpha and the subsequent effects on downstream targets critical for angiogenesis and tumour growth. The levels of p53 may also increase after Fe chelation by phosphorylation of this protein at serine-15 and -37. This prevents the interaction of p53 with murine double minute-2 (mdm-2) and its degradation. Iron chelation also markedly increases the mRNA levels of the p53-inducible cyclin-dependent kinase (cdk) inhibitor, p21(WAF1/CIP1). Surprisingly, the increase in p21(WAF1/CIP1) mRNA was not reciprocated at the protein level, and this may result in cell cycle dysregulation. This review will focus on the molecular mechanisms induced following Fe chelation and the role of Fe in cell cycle progression.
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PMID:The role of iron in cell cycle progression and the proliferation of neoplastic cells. 1224 9

Bone morphogenetic proteins (BMPs) play an essential role in cell fate determination. In this study, we found that BMP2 treatment resulted in growth arrest and differentiation in human neuroblastoma-derived cell lines, SH-SY5Y and RTBM1. Within 30min of BMP2 exposure, phosphorylation of Smad1/5 was observed in these cell lines. In RTBM1 cells, BMP2-induced differentiation was accompanied by a significant decrease in the expression level of DAN, an antagonist of BMP in frog embryos. Immunoblot analysis revealed that BMP2 treatment caused a down-regulation of p53 family members and hence of cyclin-dependent kinase inhibitor p21(WAF1). We found a significant accumulation of p27(KIP1) in response to BMP2, whereas the expression level of Skp2, which is required for ubiquitin-dependent p27(KIP1) degradation, was decreased during this differentiation process. Our results suggest that p27(KIP1) contributes to the BMP-induced growth arrest and neuronal differentiation of neuroblastoma, and BMP treatment might provide a new therapeutic strategy.
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PMID:Accumulation of p27 KIP1 is associated with BMP2-induced growth arrest and neuronal differentiation of human neuroblastoma-derived cell lines. 1285 1

The present study was undertaken to verify whether induction of senescence could be sufficient to reverse drug resistance and, if so, to determine the underlying mechanism(s). Our findings indicated that cotreatment of drug-resistant neuroblastoma cells with doxorubicin, at sublethal concentrations, in combination with the pan-caspase inhibitor, Q-VD-OPH, elicited a strong reduction of cell viability that occurred in a caspase-independent manner. This was accompanied by the appearance of a senescence phenotype, as evidenced by increased p21/WAF1 expression and senescence-associated beta-galactosidase activity. Experiments using specific inhibitors of major cellular proteases other than caspases have shown that inhibition of cathepsin L, but not proteasome or cathepsin B, was responsible for the senescence-initiated reversal of drug resistance. This phenomenon appeared to be general because it was valid for other drugs and drug-resistant cell lines. A nonchemical approach, through cell transfection with cathepsin L small interfering RNA, also strongly reversed drug resistance. Further investigation of the underlying mechanism revealed that cathepsin L inhibition resulted in the alteration of intracellular drug distribution. In addition, in vitro experiments have demonstrated that p21/WAF1 is a substrate for cathepsin L, suggesting that inhibition of this enzyme may result in p21/WAF1 stabilization and its increased accumulation. All together, these findings suggest that cathepsin L inhibition in drug-resistant cells facilitates induction of senescence and reversal of drug resistance. This may represent the basis for a novel function of cathepsin L as a cell survival molecule responsible for initiation of resistance to chemotherapy.
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PMID:Senescence-initiated reversal of drug resistance: specific role of cathepsin L. 1499 39


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