Phorbol esters and mitogenesis: comparison of the proliferative response of parental and Na+K+Cl- -cotransport-defective BALB/c 3T3 cells to 12-0-tetradecanoylphorbol-13-acetate.
The ability of the phorbol ester 12-0-tetradecanoylphorbol-13-acetate (TPA) to stimulate the growth of quiescent BALB/c 3T3 cell lines lacking Na+K+Cl- cotransport activity was tested. We have previously isolated and characterized two mutant cell lines defective in this important ion transport system by mutagenesis and selection in medium containing low K+. To test our hypothesis that loss of this transport activity might abrogate the proliferative response to TPA, two kinds of mitogenesis assays were performed. First, the effect of 0.16 microM TPA on the saturation density of parental vs. mutant cell lines was determined. TPA caused a small but reproducible 30-35% increase in the saturation density of mutant cells compared to the 100-120% increase seen in parental cell lines. Second, the effect of TPA on the incorporation of 3H-thymidine into cell nuclei (labeling index) was measured. While some variability from experiment to experiment in the extent and time course of the response of mutant cells was noted, TPA either had no effect or only a small effect on the labeling index when compared to the response of parental cells. When a range of concentrations of TPA (0.016-1.6 microM) was tested, neither cell line exhibited a large response to any concentration. These results suggest that loss of Na+K+Cl- cotransport activity decreases the response of these cells to the mitogenic action of TPA.
D000818:Animals; D002352:Carrier Proteins / Q000172:deficiency*; D002455:Cell Division / Q000187:drug effects*; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism; D007700:Kinetics; D008565:Membrane Proteins / Q000172:deficiency*; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D028021:Sodium-Potassium-Chloride Symporters; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D002352:Carrier Proteins; D002712:Chlorides; D008565:Membrane Proteins; D028021:Sodium-Potassium-Chloride Symporters; D012964:Sodium; D013755:Tetradecanoylphorbol Acetate; D011188:Potassium