Stellate- and foci-formation of mouse fibroblast cells transfected with various cancer cell DNA.

Two methods of DNA-mediated gene-transfer, namely, CaPO4 co-precipitation and polybrene/DMSO-induction were used to analyse oncogenes from various cancer cell-lines. Third time transfection of mouse fibroblast cells, NIH/3T3 with 10, 100, 1,000 and 3,000 ng of DNA from spontaneous human hepatoma cells produced 41, 4, 45 and 56 foci, respectively. It appears that 100 ng of this hepatoma cell DNA gave the least effective transformation ability. However, with two spontaneous mammary cancer cell lines, 100 ng DNA gave the highest number of foci. In general, during the initial transfection, the cells appeared semi-transformed, showing stellate growth patterns. With repeated transfections they gave way to foci. However, with aflatoxin-induced rat hepatoma cell (JB-1) DNA, only stellate growths persisted to indicate intermediate transformation. Transfection of the epithelial-like normal rat liver cell line, BL8 with JB-1 DNA produced haphazard growth pattern, although a hepatoma-associated enzyme, gamma-glutamyl transferase was introduced into the BL8 cells which previously had no detectable enzyme activity.