Identification of tumor promoters by their inhibitory effect on intercellular transfer of lucifer yellow.

The effect of the tumor promoters 12-O-tetradecanoylphorbol-13-acetate (TPA), mezerein, teleocidin, anthralin, the Ca2+-ionophore A23187, butylated hydroxytoluene (BHT), dichlorodiphenyltrichloroethane (DDT) and phenobarbital (PB) on lucifer yellow transfer in cultures of SV-40-transformed Djungarian hamster fibroblasts was studied. TPA, mezerein, teleocidin, A23187, DDT and BHT exerted a strong inhibitory effect on cell-to-cell dye transfer. Anthralin uncoupled cells in 3 experiments out of 6. PB appeared to enhance lucifer yellow transfer. Sodium nitrite, a substance with unknown promoting activity, effectively uncoupled cells. All the promoters investigated had a reversible effect on the dye transfer. The value of the dye transfer method for promoter screening is discussed.