Changes in the expression of the alpha alpha form of enolase during neuroblastoma differentiation

Regulation of neuron-specific enolase isozyme levels during differentiation of murine neuroblastoma cell cultures

A specific event which accompanies the terminal differentiation of most neurons is the isozymic enolase transition from the ?? form to the ?? and ?? adult neuronal forms. It is partly expressed during maturation of a mouse neuroblastoma clonal cell line (NIE-115). We demonstrate, in these cell cultures, that the significant increase in the concentration of ? gene product, expressed as ?? enolase during differentiation, is due to a parallel and similar increase in its synthesis. The capacities of poly (A)(+) RNA from undifferentiated and differentiated cultures to direct the synthesis of ? gene product were compared in a reticulocyte cell-free protein-synthesizing system. This translating capacity is stimulated in the same proportion as the rate of synthesis of ? antigen in differentiating cell cultures. Therefore the increase in the level of ? protein (expressed mostly as ?? enolase) during differentiation results from the increased translating activity or relative amount of ?mRNA.

Differential expression of neuron-specific enolase mRNA in mouse neuroblastoma cells in response to differentiation inducing agents

1. The mouse neuroblastoma cell line N-115 was used as a model system to study neuronal differentiation induced by treatment of cells with different agents. 2. The extent of morphological differentiation obtained with dibutyryl cyclic AMP (dbc-AMP), dimethyl sulfoxide (DMSO), retinoic acid (RA), and serum-free medium was correlated to the expression of the mRNA for the gamma isoform of the glycolytic enzyme enolase, a recognized neuron-specific marker. 3. A 4-day treatment of the cells with any of the differentiation inducing agents used in this study resulted in the extension of long neurites, though differences in cell body shape were observed depending on the agent used. 4. Northern blot analysis revealed that changes in the level of gamma enolase-specific mRNA correlate with the extent of morphological differentiation, with a 5- to 20-fold increase depending on the differentiation inducing agent used. 5. Finally, we found that a high cell density causes a significative increase in the level of the gamma enolase-specific message in cells maintained in growing conditions.

Serum neurone-specific enolase levels in patients with neuroendocrine and carcinoid tumours

We have examined concentrations of neurone-specific enolase (NSE) in sera from 18 patients with various neuroendocrine tumours, 26 patients with carcinoid tumours, 21 patients with non-neuroendocrine tumours and 37 control individuals. No statistically significant difference between the concentrations in patients with neuroendocrine tumours and patients with carcinoid tumours was found. However the NSE concentrations in patients with carcinoid and neuroendocrine tumours, when these two groups were combined, were significantly different from the patients with non-neuroendocrine tumours or the control individuals (P < or = 0.01). 38.5% of the patients with carcinoid tumours had raised NSE concentrations in serum; 55.5% of those with non carcinoid neuroendocrine tumours had raised concentrations. There appeared to be no correlation between the NSE concentrations and the extent of metastases.

Complexities and sequence similarities of mRNA populations of cholinergic (NS20-Y) and adrenergic (N1E-115) murine neuroblastoma cell lines

The clonal murine neuroblastoma cell lines NS20-Y and N1E-115 have been proposed as models for examining the commitment of neural crest cells to either the cholinergic or adrenergic phenotype, respectively. The validity of this model depends in part on the extent to which these two cell lines have diverged as a result of their transformed, rather than neuronal properties. In order to quantitate differences in gene expression between NS20-Y and N1E-115 cells, the mRNA complexity of each cell type was determined. An analysis of the kinetics of hybridization of NS20-Y cell mRNA with cDNA prepared from NS20-Y cell mRNA demonstrated the presence of approximately 11,700 mRNA species assuming an average length of 1900 nucleotides. A similar analysis using mRNA isolated from N1E-115 cells and cDNA prepared from N1E-115 cell mRNA demonstrated that the adrenergic cell line expressed approximately 11,600 mRNA species. The species of mRNA expressed by each cell line were resolved into high, intermediate, and low abundance populations. In order to determine whether mRNAs were expressed by the cholinergic, but not by the adrenergic cell line, NS20-Y cDNA was hybridized to an excess of N1E-115 cell mRNA. An analysis of the solution hybridization kinetics from this procedure demonstrated that the two cell lines do not differ significantly in the nucleotide complexity of their mRNA populations. The extensive similarity between the two mRNA populations suggests that only a small number of genes are expressed differentially between the two cell lines and supports their use as models for the differentiation of cholinergic and adrenergic neurons.

Binding of peanut agglutinin to neuroblastomas and ganglioneuromas: a marker for differentiation of neuroblasts into ganglion cells

Binding of peanut agglutinin (PNA), concanavalin A, Ricinus communis agglutinin, wheat germ agglutinin, soybean agglutinin, Ulex europaeus agglutinin 1, and Dolichos biflorus agglutinin was assessed in tissue sections of 4 cases of neuroblastoma (NB) to determine whether there were any differences in lectin binding among immature neuroblasts, maturing neuroblasts, and ganglion cells. Only PNA binding proved to be useful. This was assessed more fully in 17 cases of NB and 7 ganglioneuromas. PNA bound to immature neuroblasts in only 4 of 12 stroma-poor NB but to maturing neuroblasts and ganglion cells in 5 of 5 stroma-rich NB. PNA bound to ganglion cells in all 7 ganglioneuromas. The NB were categorized as favorable (7 cases) and unfavorable (10 cases), using the patients' ages and the histologic appearance and mitotic-karyorrhetic index of the resected tumor, and this was correlated with PNA binding. PNA bound to 6 of 7 NB with a favorable, and 3 of 10 with an unfavorable histologic type of NB (p less than 0.05). These studies suggest that neuroblasts acquire the capacity to bind to PNA as they differentiate into ganglion cells and that PNA binding is indicative of a favorable histologic type of NB.

Isolation of murine neuron-specific and non-neuronal enolase cDNA clones

cDNA clones corresponding to subunits of neuron-specific (gamma gamma and alpha gamma) and non-neuronal (alpha alpha) enolase isozymes were characterized from two mouse brain cDNA libraries. Our hybridization data revealed a partial homology of the coding sequences of mouse alpha, mouse gamma and rat gamma mRNAs. The noncoding sequences, however, appear to be specific for each mouse mRNA. Although coding for two polypeptides of the same molecular weight, the mRNA for the gamma subunit (2600 bases) is larger than that for the alpha subunit (1900 bases). The noncoding sequences for neuron-specific gamma mRNA (about 1300 bases) are therefore longer than those of the non-nervous tissue specific alpha mRNA (about 600 bases).

Developmental changes in levels of translatable mRNAs for enolase isozymes in chicken brain

Using chicken brain mRNAs, alpha and gamma enolase precursors were synthesized in the rabbit reticulocyte cell-free translation system. The product proteins showed molecular weights almost identical to those of the mature subunits. The levels of translatable mRNAs for alpha and gamma subunits were determined by the cell-free translation system and immunoprecipitation with specific antisera, during development of chicken brain. The level of alpha mRNA was high at any developmental stage of the brain. On the other hand, the gamma mRNA level was very low at the early embryonic stage, and increased rapidly during development of the brain. These changes were closely correlated with those of the corresponding enzyme activities, indicating that the levels of enolase activities in developing brain were controlled primarily by the level of the translatable alpha and gamma mRNAs.

Enzymes and pathways of glucose utilization in bovine adrenal medulla

Glucose utilization by different metabolic pathways in bovine adrenal medulla has been studied using freshly isolated adrenal chromaffin cells. The rate of net glucose utilization in resting cells was 10.5 mumoles X g-1 X h-1. 50% was transformed into lactate and pyruvate, the lactate to pyruvate ratio ranging from 3 to 7.27% was metabolized through the tricarboxylic acid cycle and 3.1% was oxidized in the pentose phosphate pathway. The ratio of 14CO2 production from [1-14C] glucose and [6-14C] glucose was close to 2 at one hour of incubation. 3.2% of total glucose consumed was used in protein synthesis, and 1% was incorporated into lipids. Oxygen utilization in respiration by isolated adrenal chromaffin cells was 18.2 mumoles X g-1 X h-1, corresponding to 3.1 mumoles glucose X g-1 X h-1 or about 30% of total glucose consumed. The activities of hexokinase, enolase, pyruvate kinase, lactate dehydrogenase, glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were assayed in extracts of bovine adrenal medulla, being 1.0, 23, 40, 37, 6.0 and 3.0 U/g respectively. Hexokinase activity was identified as belonging mainly to isoenzyme I, with some isoenzyme II. Enolase was predominantly the alpha gamma hybrid. Pyruvate kinase activity corresponded to a mixture of isoenzymes K and M. Lactate dehydrogenase activity corresponded to isoenzymes 1, 2 and 3, with smaller proportions of isoenzymes 4 and 5. Results are discussed mainly with respect to those reported for the brain.