| Abstract: | Glycoconjugates have been analyzed from a family of closely related mouse cells: a parent clone and three daughter subclones, two of which expressed the simian virus 40 (SV40) T-antigen. The experimental procedure involved the simultaneous comparison by DEAE-cellulose chromatography of papain-digested macromolecules from the parent, labeled with [3H]glucosamine, and one of the daughter subclones, labeled with [14C]-glucosamine. Three cultures compartments (the medium, the cell surface trypsinate, and the cells) from the paired cell lines were combined at the earliest time during the harvesting of the cells. Heparan sulfate on the surface of cells and secreted into the medium from T-antigen-positive subclones was eluted at lower salt concentrations from the anion exchange column than that from the parent clone. In the viable trypsinized cells a marked reduction of heparan sulfate was detected in the T-antigen-positive subclones. These changes were highly reproducible, were observed during both logarithmic and stationary phase of growth, and neither change was observed in the T-antigen-negative sister subclone. The elution point of heparan sulfate from Sepharose 6B was unaltered. Ratios of 35S to 3H for heparan sulfate obtained from cells doubly labeled with [35S]sulfate and [3H]glucosamine were lower in the T-antigen-positive subclones. Similar changes for the 35S to 3H ratio of chondroitin sulfate were associated with only small alterations in elution from anion exchange columns. Kinetic experiments suggested a reduced rate of incorporation of [35S]sulfate with no change in turnover rate. A substantial portion of the labeled heparan sulfate was associated with the cell surface; in contrast most of the hyaluronic acid and a large proportion of the chondroitin sulfate was apparently secreted. Quantitative changes in hyaluronic acid labeling did not correlate with expression of T-antigen. Glycosaminoglycans left on the dish after detaching cells with ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid were nearly completely released by subsequent trypsinization. Cell detachment by trypsinization left an insignificant amount of labeled glycosaminoglycan on the dish surface. The alterations in heparan sulfate metabolism correlated with the expression of T-antigen and with the cells' ability to grow to high densities in monolayer culture, but not with growth in suspension in viscous medium. Tumorigenicity of the subclones was essentially the same as that of the parent clone. |
