INHIBITION OF THE FORMATION OF ELECTRICAL CELL COUPLING OF FL CELLS BY TUMOR PROMOTERS

Abstract

The effect of tumor promoters on the formation of electrical cell coupling between human FL cells was investigated by means of a microelectrode technique. In culture medium containing 100 ng/ml of 20-O-tetradecanoyl phorbol-13-acetate (TPA), only 6% of the cells were coupled after 24 h while > 90% of the cells were coupled in control medium. The formation of cell coupling was inhibited by other tumor promoters, phorbol-12,13-didecanoate, ingenol-13,20-dibenzoate and mezerein; non-promoting derivatives, phorbol and 4.alpha.-phorbol-12,13-didecanoate, did not affect cell coupling formation. 7,12-Dimethylbenz[a]anthracene, benzo[a]pyrene and N-methyl-N''-nitro-N-nitrosoguanidine did not affect the cell coupling. None of the chemicals used changed any electrical properties of the cell membrane, such as membrane potential and membrane resistance, of FL cells. It appears that TPA and other related tumor promoters inhibit the formation of cell coupling without changing the physiological properties of the membrane significantly.