In vitro assay for tumor promoters and anti-promoters

Tumor promoters and anti-promoters have been shown to modify the induction of ornithine decarboxylase, the production of plasminogen activator, and the recovery of induced mutations. Data were presented to show that the recovery of mutagen-induced ouabain-resistant mutations in cultured Chinese hamster cells is increased with a tumor-promoter treatment and reduced by anti-promoter treatments. The results suggest that many induced mutations can either be repressed or derepressed by promoters or anti-promoters. The results also support the hypothesis that tumor initiation is due to a mutagenic event, while tumor promotion is the result of an epigenetic process involving cyclic nucleotide modulation of gene expression.