Generation of adhesive tumor variants: Chromosomal changes, reduction in malignancy and increased expression of a distinct membrane glycoprotein

Abstract

Tumor cell variants which grow adherent to a plastic surface could be isolated in a reproducible way from the high metastatic tumor cell line ESb which grows in a suspension culture. This occurred when starting selection from the uncloned parental line as well as from a freshly derived non-adhesive subclone. The variants showed changes in their karyotype. These were quantitative (tetraploidization) and qualitative (single chromosome aberrations involving the chromosomes 12 and 17 and a marker MX-7). Phenotypic cell surface changes were documentedin vitro by immunofluorescence using a monoclonal antibody (mAb 12–15) directed against a distinct plasma membrane glycoprotein of 60–69 kD (gp 60–69). The expression of gp 60–69 increased with time of selection for adherence to plastic surface. The adherent cells showed in all cases a greatly reduced overall malignancy as seen by a prolonged survival time of respective tumor bearing animals compared with the suspension growing parental cells.