Reversibility of the transformed and neoplastic phenotype. III. Long-term treatment with electrophoretically pure mouse interferon leads to the progressive reversion of the phenotype of X-ray transformed C3H/10T1/2 cells.

Electrophoretically pure mouse interferon induced the progressive reversion of the transformed phenotype of a clone of X-ray transformed C3H/10T1/2 cells. Cells of this clone did not harbor C-type particles and reverse transcriptase activity was not detected. Interferon-treated transformed cells were aligned without cellular overlapping and attained low cell densities. Morphologic changes were associated with the appearance of a thick layer of submembranous microfilaments. The tumorigenicity of interferon-treated cells was markedly reduced. Back reversion to the transformed phenotype occurred progressively when these cells were passaged in the absence of interferon. These results suggest that interferon may induce the reversion of the transformed phenotype by a mechanism other than by its antiviral activity.