1974 Articles

A nonselective analysis of SV40 transformation of mouse 3T3 cells

Risser, Rex; Pollack, Robert

Mouse cells transformed by simian virus 40 show many alterations in their growth properties in vitro. In order to investigate the coordinate nature of these changes, we have analyzed the growth properties of 40 randomly selected colonies arising after SV40 infection of 3T3 cells. Clones of cells, established from these colonies, were characterized as to saturation density and doubling time in 10% and 1% calf serum, growth in methyl cellulose suspension, colony formation on monolayers of normal cells, and presence of viral antigens. This analysis revealed that only 5 of the clones were indistinguishable from 3T3 cells; the remaining 35 clones differed from 3T3 cells in that they grew as rapidly in 1% calf serum as standard SV40 transformed cells. Of these 35 clones, ten corresponded to standard transformants previously described. Another ten showed other growth properties intermediate between 3T3 cells and standard transformants. These intermediate clones had lower levels of viral T-antigen than standard transformants and showed considerable heterogeneity in staining from cell to cell. The remaining 15 clones were T-antigen negative and had saturation densities slightly higher than that of 3T3 cells. These changes in cellular behavior are stable on recloning.