Cell surface alpha-D-galactopyranosyl end groups: use as markers in the isolation of murine tumor cell lines with different cancer-causing potentials.

Cell lines from 2 3-methylcholanthrene-induced murine tumors were established in culture and examined for reactivity with Griffonia simplicifolia isolectin B4 (GS I-B4), a lectin that has strict specificity for terminal alpha-D-galactopyranosyl residues. Virtually all of the cells in both populations were strongly reactive, indicating the presence of this carbohydrate on the cell surface. Both tumor lines were exposed to human serum with antibodies to the blood group B antigen. More than 99.99% of the exposed cells were killed by this treatment. This is not surprising, because terminal alpha-D-galactopyranosyl residues comprise the blood group B antigen. From the few surviving cells, it was possible to establish cell lines resistant to the cytotoxic effects of the anti-blood group B antibodies. A total of 4 cell lines were independently obtained in this way. The human serum-resistant lines showed no detectable reactivity with GS I-B4, indicating that alpha-D-galactopyranosyl-deficient cell lines had been obtained. The parent and variant cells were compared for reactivity with anti-laminin antibodies. Both parent lines showed strong reactivity by immunofluorescence in the viable state, whereas the alpha-D-galactopyranosyl-deficient lines showed no reactivity. The parent and variant lines were also compared with regard to in vitro and in vivo growth. The alpha-D-galactopyranosyl-deficient lines had reduced in vitro growth capacity relative to the parent lines. More importantly, in contrast to the parent lines, these lines were significantly less tumorigenic than the parent lines when injected into syngeneic mice and did not metastasize spontaneously.