Antisense RNA of proto-oncogene c-fos blocks renewed growth of quiescent 3T3 cells.

Mouse 3T3 cells were transformed with an antisense c-fos gene fused to a mouse mammary tumor virus promoter. In transformants that integrated a large number of antisense c-fos sequences, the usual large increase in c-fos mRNA and protein following stimulation of quiescent cells by platelet-derived growth factor was blocked in the presence of dexamethasone. These cells subsequently also failed to show the stimulation of DNA synthesis normally induced by platelet-derived growth factor. Appropriate expression of c-fos appears to be a prerequisite for reentry of quiescent cells into the cell cycle.