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NIH 3T3 cells were transfected with DNA derived from human bladder carcinoma, colon carcinoma and HL60 promyelocytic leukemia cells. The transfectants were examined for the presence of human oncogenes in relation to tumorigenic potential and composition of surface-located fucosyl glycopeptides by gel filtration, Concanavalin-A-binding and high-performance liquid chromatography. All transfectants, harboring 3 different human cellular ras genes, appeared to be tumorigenic in nude mice and displayed characteristically altered glycopeptides. The surface glycopeptides were consistently changed to higher apparent molecular weight due to enrichment in higher-branched sialic-acid-containing glycopeptides. Similar alterations have been found previously in virally- and chemically-transformed cells in vitro and tumors raised in vivo, and were designated as cancer-related or tumor-associated glycopeptides. Revertants derived from HL60-DNA-induced transfectants, which had lost the transfected human N-ras oncogene, simultaneously lost their tumorigenic potential and expression of cancer-related membrane glycopeptides. In addition, spontaneous transformants, exhibiting morphology and growth patterns indistinguishable from those of tumor-DNA-induced transfectants, neither contained transferred human DNA sequences nor expressed cancer-related glycopeptides. Nevertheless these cells were capable, after prolonged latency periods, of inducing tumors in nude mice. Cells derived from such tumors constantly displayed cancer-related glycopeptides on their surface, suggesting selection of tumorigenic cells from spontaneous transformants during passage in nude mice. In one of these tumors at least, an endogenous mouse ras-gene appeared to be activated. The results indicate a close correlation between the presence of activated ras-oncogenes in the genome of the transfected cells, the tumorigenic potential of these cells and the expression of surface-located cancer-related glycopeptides. The data suggest that functions provided by human ras-oncogenes contribute to the alteration of membrane glycopeptides on tumor cells.

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Cell strains isolated from an established line of SV40-transformed mouse 3T3 cells (SV3T3) showed large variations in the various parameters of transformation, viz. saturation density, serum requirement, contact inhibition of movement and of growth and Concanavalin-A-mediated agglutinability. These cell strains were studied for changes in elution profiles of fucose-labelled surface glycoproteins, using actively growing, untransformed 3T3 cells as controls. A cell strain established from a tumour arising after injection of wild-type SV3T3 cells and SV3T3 cells grown in vivo in diffusion chambers, was similarly studied. Changes in surface glycoproteins were observed only in the tumour-derived cell strain. The results suggest that alterations in surface glycoproteins are associated with the tumorigenic potential of the cells rather than with the transformed phenotype per se.

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.

The mechanism of emptying and filling of pore domains along the adsorption as well as the desorption boundary curve of the hysteresis loop was studied by the determination of a V-S curve derived from the tangents to primary scanning curves immediately after a pressure reversal at the boundaries of the hysteresis region. In all three cases studied, the V-S curve for the desorption process exhibits a discontinuity aroundp,/po = 0.5, pointing to a sudden breakdown of the capillarycondensed state, which is not directly related to the detailed domain properties of the system. This breakdown of the capillary-condensed state invalidates in a number of cases the usual procedures for obtaining pore size distributions. The filling of slit-shaped pores was found to proceed most probably by additional sorption of one to two nitrogen molecules between adjacent adsorbed layers.