Transformation-dependent loss of the hyaluronate-containing coats of cultured cells.

The sizes of hyaluronate-containing coats on the surfaces of parent and virus-transformed cell lines (3T3 vs. SV-3T3; BHK vs. PY-BHK) were compared according to the method of Clarris and Fraser (1968, Exp. Cell Res., 49: 181-193) in which fixed red blood cells were allowed to settle slowly on the surface of culture dishes containing the cells. The coats were seen as areas devoid of red blood cells surrounding each of the cultured cells and could be destroyed by the addition of small amounts of streptomyces hyaluronidase, an enzyme specific for hyaluronate. In the case of the parent cell lines (3T3 and BHK), the coats were clearly visible, whereas for their virus-transformed counterparts (SV-3T3 and PY-BHK), the coats were either greatly reduced or absent. To confirm these observations, the amount of hyaluronate associated with each of the cell lines was measured using a direct chemical assay and shown to be significantly greater for the parent cell lines than for their virus-transformed counterparts. In addition, the parent cell lines secreted greater amounts of hyaluronate into the medium and retained a larger fraction of the total amount of hyaluronate at the cell surface than the virus-transformed cells. Thus the larger amount of hyaluronate on the surfaces of the parent cell types may be the result of both a faster rate of production and a decreased rate of release.