Regulation of cyclic amp level and synthesis of DNA, RNA and protein by quercetin in ehrlich ascites tumor cells

Quercetin (3.3, 4′, 5.7-pentahydroxy flavone) at the concentration of 10^-4 M as well as 10^-2 M theophylline and 10^-3 M dibutyryl cyclic AMP caused at least 85 per cent inhibition of [³H]thymidine incorporation in Ehrlich ascites tumor cells. At the same concentrations, these drugs decreased [³H]uridine and [³H]-L-leucine incorporation by 50-60 per cent and 35-45 per cent respectively. Ouabain (10^-3 M), the specific inhibitor of Na⁺-K⁺ pump system, did not alter the incorporation of [³H]thymidine and [³]uridine, but decreased the incorporation of [³H]-L-leucine in these cells. Treatment of Ehrlich ascites tumor cells with the polyanion dextran sulfate did not change the inhibitory effect of quercetin, theophylline and dibutyrlyl cyclic AMP on [³H]thymidine incorporation. On the other hand, this polyanion decreased the inhibitory effect of these drugs on incorporation of [³H]uridine and abolished completely their effect on incorporation of [³H]-L-leucine.