Effect of Insulin on the Growth Pattern and Adenylate Cyclase Activity of BHK Fibroblasts

BHK 21/13 fibroblasts grown in the presence of insulin show some characteristics of a transformed strain. Cells broaden, cross each other intricately, and form colonies on both polystyrene dishes and soft agar. The effect of insulin is prevented by addition of N6-butyryl adenosine 3′:5′-cyclic monophosphate and theophylline to the culture medium. Insulin causes a decrease in the concentration of intracellular adenosine 3′:5′-cyclic monophosphate and inhibition of adenylate cyclase activity in BHK fibroblast membranes. This inhibition is observed at insulin concentrations of 0.1 nM or higher.