Polysialic acid in human neuroblastoma cells
Prokaryotic-derived probes that specifically detect ..cap alpha..-2,8-linked polysialic acid (PSA) units on embryonic neural cell adhesion molecules (N-CAM) were used to show that membrane glycoproteins (GPs) from metastatic human neuroblastoma cells (CHP-134) also contain these unique carbohydrate moieties. This conclusion was based on the following evidence: (1) membranes from CHP-134 cells served as an exogenous acceptor of (/sup 14/C)NeuNAc units in an E. coli K1 sialyltransferase (ST) assay. The bacterial ST is specific for the transfer of (/sup 14/C)NeuNAc to exogenous acceptors containing at least 3 sialyl units (DP3); (2) in SDS-PAGE, the (/sup 14/C)NeuNAc-labeled CHP-134 membranes showed a major peak of radioactivity that was polydisperse. N-CAM shows a similar Mr heterogeneity; (3) treatment of the high Mr CHP-134 product with Endo-N-acetylneuraminidase (Endo-N) released the (/sup 14/C)NeuNAc label as a DP4. Endo-N is specific for hydrolysing ..cap alpha..-2,8-linked PSA chains containing a minimum of 5 sialyl residues; (4) treatment of the DP4 with sialidase converted the label to (/sup 14/C)NeuNAc, thus proving the tetramer contained sialic acid; (5) CHP-134 cells were labeled in vivo with (/sup 3/H)GlcN. A glycopeptide fraction representing ca. 1% of the (/sup 3/H)GlcN incorporated was isolated. Based on Endo-N sensitivity, this glycopeptide contained at least 15-20% of the (/sup 3/H)GlcN label as PSA. Endo-N digestion of the (/sup 3/H)-labeled glycopeptide released (/sup 3/H)-DP4. These results suggest that the surface expression of PSA-containing GPs may be important in neuroblastoma metastasis.
- Research Organization:
- Univ. of California Medical School, Davis
- OSTI ID:
- 5904426
- Report Number(s):
- CONF-870644-; TRN: 87-037160
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 46:6; Conference: 78. annual meeting of the American Society of Biological Chemists conference, Philadelphia, PA, USA, 7 Jun 1987
- Country of Publication:
- United States
- Language:
- English
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