Butyrate prevents Harvey Sarcoma virus focus formation but permits oncogene expression

Since butyrate inhibits DNA synthesis and cell growth, we adapted NIH 3T3 cells to grow in butyrate to study its effects on retroviral cell transformation. In cultures of butyrate-adapted NIH 3T3 cells infected with Harvey Sarcoma Virus, no foci were formed; however, there was evidence of retroviral replication, and the P21 oncogene product was demonstrated by immunofluorescence in its characteristic localization beneath the cytoplasmic membrane of single cells and pairs of cells. When the butyrate was removed, these cells proliferated to form foci. Butyrate therefore does not prevent oncogene expression but does reversibly inhibit focus formation.