Effect of dibutyryl cyclic AMP on the growth of B16 melanoma cells In Vitro and on the synthesis of nonhistone chromosomal protein

Ditratyryl cyclic AMP was found to cause a marked decrease in the growth rate of B16 melanoma cells in vitro. Accompanying the inhibition of growth were marked alterations in cell morphology and a decrease in agglutinability by Concanavalin A, a monitor of surface changes in the plasma membrane. Control cells reached confluency after three days incubation but continued to proliferate and eventually sloughed off into the growth medium. Cells grown in the presence of dibutyryl cyclic AMP reached confluency after four days incubation, whereupon there was a marked decrease in the growth rate. Electrophoretic banding patterns of nonhistone chromo- somal proteins revealed an increase in the synthesis of high molecular weight nonhistone proteins of cell s grown in the presence of dibutyryl cyclic AMP.