Altered growth behavior of malignant cells associated with changes in externally labeled glycoprotein and glycolipid

By use of galactose oxidase (EC 1.1.3.9), followed by reduction with tritiated sodium borohydride, the surface structures of transformed 3T3 and NIL cells, under ordinary growth conditions, were characterized by (i) deletion of the normally existing glycoprotein label and (ii) appearance or increase of a new glycoprotein label. NIL cells had a galactoprotein label with molecular weight 200,000 that was deleted in NIL cells transformed by polyoma virus. 3T3 cells had a glycoprotein label with molecular weight of 30,000 that was lost after transformation. Glycoproteins of transformed 3T3 cells, with molecular weight 105,000, and those of transformed NIL cells, with molecular weight 85,000, were not labeled in normal confluent cells, but became labeled after trypsin treatment. The label in glycolipids was quantitatively different in normal and transformed cells. The labeling pattern in glycoprotein and glycolipids of transformed NIL and 3T3 cells became similar to that of nontransformed cells when contact responses of transformed cells became conspicuous when cells were cultured in the presence of dextran sulfate or dibutyryl cyclic adenosine monophosphate, or in medium in which glucose was replaced with galactose.