Comparison of cell-surface glycoproteins of rat hepatomas and embryonic rat liver

Abstract

Summary.-Cell-surface glycoprotein of 3 rat hepatoma strains and late-embryonic liver was metabolically labelled in vivo with [3H]-or [14C]-fucose. Trypsinization of the cells and exhaustive pronase digestion of combined hepatoma-liver trypsinates followed by gel filtration over Sephadex-Biogel mixtures, yielded elution profiles that contained more early-eluting (high-mol.-wt.) glycopeptides for hepatomas than for liver. At least 3 factors were identified which acted to augment the fraction of earlyeluting tumour glycopeptides: (a) increase of neuraminidase-sensitive sialic acid, (b) increase of neuraminidase -insensitive sialic acid that was sensitive to mild HCI hydrolysis, and (c) presence of sugar sulphate groups contributing to a restricted extent, relative to possible unknown factor(s). Whether (a), (b) or (c) operated depended on the hepatoma strain or its mode of growth. Notwithstanding these differences in the nature of the increase in early-eluting glycopeptides, the increase itself appears not to be due to growth per se, nor to an embryonic expression, but rather may serve as a marker of tumourigenicity.

Early changes in the glycopeptides of human B‐lymphocytes after epstein‐barr virus infection in vitro

“…5) expose fast-eluting fucosyl glycopeptides when compared with stationary B and T lymphocytes respectively. From these and earlier results (Van Beek et al, 1977a, 1979a and from the results of De Leij et af. (ms. submitted) we may conclude that growth as such is not instrumental in the generation of the fast-eluting glycopeptides.…”

N‐Acetylglucosaminyltransferase III, IV and V activities in Novikoff ascites tumour cells, mouse lymphoma cells and hen oviduct

“…These enzymes are probably involved in the synthesis of linear and branched polylactosaminoglycans and p6-GlcNAc-containing mucin core structures, respectively. Like many other malignant cells [3 -71, Novikoff cells have been reported to express cell-surface glycans of higher molecular mass relative to those present in their normal counterpart (embryonic rat liver) [26]. In view of the specificities of the GlcNAc transferases [ l l , 13, 18, 25, 271 it might be predicted that the N-linked cell-surface glycans of Novikoff cells are predominantly of the bisected type and contain only few lactosaminoglycan elongations, whereas the 0-linked chains contain N-acetyllactosamine repeats in linear or branched chains that are attached to Ga1/31+3(GlcNAc/31 j6)GalNAc and GlcNAcfll 4 3(GlcNAc/31+6)GalNAc much cores.…”

“…2 values (Table 2) revealed that its structure was that shown for oligosaccharide bis-tri ( at a probe temperature of 300 K. Chemical shifts are expressed downfield from internal sodium 4,4-dimethyl-4-silapentane-1-sulfonate, but were actually measured by reference to internal acetone (6 = 2.225 ppm) with an acuracy 0.002 pprn. The numbering of the residues is according to the system used in [26].…”

Significance of glycosylation patterns of rat Zajdela ascitic hepatocellular carcinoma: Effect of enzymatic removal of surface sialic acid on humoral response

“…Our observations of the decrease in ConA-binding activity and increase in sialylation of the glycoproteins in the ZAH cells are similar to those made earlier in different transformed cell systems, including HCC. 16,25,29 The increase in sialylation of the membrane glycoproteins upon transformation has mainly been attributed to increased branching of N-linked glycoproteins; 8 however, gp120 in ZAH appears to be an O-linked oligosaccharide as it does not bind to LCA or PHA-P, although ZAH C membranes contain at least one specific fucose-containing N-linked complex-type sialoglycoprotein also. The presence of sialylated O-linked and N-linked glycoproteins, as observed in our system, has also been reported in a number of rat ascites HCC 27,30 and in Novikoff HCC.…”