Human neuroblastoma has several unique features: (1) it is limited to young children; (2) there is tumor regression in some cases; (3) its chromosomes contain homogeneously staining regions (HSRs) with an amplified DNA sequence weakly homologous to oncogene c-myc, called N-myc. The presence of multipled HSRs, each containing amplified copies of N-myc, have been demonstrated in two all lines; (4) there is the presence of oncogene N-ras capable of transforming NIH 3T3; and (5) its glycoproteins contain unusually large amounts of fucose linked alpha 1+3 to N-acetylglucosamine on the oligosaccharide antennae. An alpha-L-fucosidase from almonds, specific for fucosyl residues linked alpha 1+3(4) to N-acetylglucosamine, was used to demonstrate that these fucosyl residues were present on glycoproteins of neuroblastoma cell lines and tumors including tumor cells purified from the bone marrow and not on those from other cell types. Thus, the neuroblastoma glycoproteins provide a unique opportunity to define a structural basis for a particular tumor specificity and to determine structural characteristics and, hence, information about synthesis for a range of unusual glycopeptides. Selected glycopeptides from neuroblastoma glycoproteins will be studied after purification by HPLC, conventional size and charge chromatography, and lectin binding. Tentative structural assignments will be made from the purification properties and will be verified by high resolution 'H-NMR spectroscopy. This information will be used to describe the range of structures containing these specific fucosyl residues. Further, it will be used to select substrates for assaying fucosyl and sialytransferases in these cells. It is anticipated that correlation of the structural and enzymatic data will define the gene product specifically amplified or expressed in neurectoderm tumors. Transfection with human neuroblastoma DNA containing oncogene N-ras will transform mouse fibroblasts, NIH 3T3. These transformants have glycoproteins containing oligosaccharide residues more highly branched than those of NIH 3T3. Selected glycopeptides from both cell types will be purified, and the oligosaccharide structures determined. The structural information will be used to design a series of exploratory experiments to test a number of alternate causes of the change in oligosaccharides after oncogene transformation. These experiments will: (1) measure the activity of relevant glycosyl transferases; and (2) assess positional alterations on the polypeptide using inhibitors of early stage glycoprotein processing. Progress has been made isolating glycopeptides from human neuroblastoma, CHP-134, oncogene transformed alpha 1-1, and nontransformed NIH-3T3 cells. In addition, the initial studies using inhibitors of glycoprotein processing have shown this to be a valid approach. (A)
