ABSTRACT
Previous studies have indicated that an early-passage type 5 adenovirus temperaturesensitive mutant (Hsts125) transformed secondary rat embryo clone exhibited in vitro growth properties which resembled the normal secondary rat embryo (2°RE) parental cells (Fisher, Goldstein & Weinstein, 1979 a). In contrast, clones of early-passage chemical carcinogen, benzo(a)pyrene (BP) or 7,12-dimethylbenz(a)anthracene (DMBA), pretreated viral transformants displayed a greater phenotypic expression of certain in vitro markers of transformation. In the present study, we have analysed the glycoproteins, glycopeptides and cell-surface proteins of normal and cloned populations of early passage solvent and chemical carcinogen-pretreated H5ts125 transformed 2°RE cells to determine if any systematic changes in surface composition had occurred in the different cell types.
When compared with normal 2°RE cells, all of the viral transformants exhibited a reduction in cell surface fibronectin (LETS protein) ranging from 25 % (solvent-pretreated culture) to 84 % (a DMBA-pretreated clone). This surface marker, however, did not accurately reflect the state of transformation of the individual clones, as indicated by cloning efficiency in agar, production of plasminogen activator, etc. Similarly, whereas the carcinogen-pretreated Hgtsizs-transformed clones showed a slight molecular weight shift in glucosamine-labelled glycopeptides, when run on Sephadex G-50 columns in parallel with 2°RE glycopeptides, this surface change also was not a good indicator of adenovirus transformation of 2°RE cells. On the other hand, a distinctive change which was observed in all of the carcinogen-pretreated H5ts125-transformed clones, but not in the normal 2°RE or solvent-pretreated transformed cells, was an increase in a glycoprotein of approximately 100 K molecular weight. A protein of similar molecular weight has been described by Bramwell & Harris (1978) to correlate with in vivo malignancy and may also be a good indicator for carcinogen-pretreated adenovirus-transformed 2°RE cells or Hsts125 transformants exhibiting anchorage-independent growth.
