Partial reversion of the transformed phenotype of murine sarcoma virus-transformed cells in the presence of interferon: a possible mechanism for the anti-tumour effect of interferon.

The effect of interferon (IFN) on a series of cellular properties which characterize the transformed state was studied, using normal mouse fibroblasts (both established lines and embryo cells) and cloned derivatives transformed by murine sarcoma virus. It was found that the transformed cells behaved in a more normal fashion in the presence of IFN. This was indicated by reduction in saturation density, decreased DNA synthesis in crowded cultures, decreased formation of foci on monolayers of normal cells, and decreased growth in soft agar. These effects were not due to generalized inhibition of cell growth, since IFN had little effect on the growth and cloning efficiency of the cells used. In the presence of IFN, cellular morphology also appeared more normal. These results suggest that growth control of transformed cells may be at lease partly restored by IFN, an effect which could in part account for the anti-tumour effect of IFN