Effect of cyclic AMP on cells of experimental lymphatic leukemia L-5718

The effect of cyclic AMP (cAMP), dibutyryl-cAMP, and theophylline (an inhibitor of phosphodiesterase, the enzyme converting adenosine-3, 5-monophosphate into adenosine-5-monophosphate) on the intensity of proliferation (as reflected in the increase in the nucleic acid content in the culture), DNA synthesis (thymidine-H³ incorporation), and transplantation properties (ability to repopulatein vivo) of leukemic cells of strain L-5178 was studied. The experiments showed that cAMP in a concentration of 0.8 mM inhibits thymidine-H³ incorporation considerably, retards proliferation, and reduces the transplantability of the leukemic cells. Theophylline and dibutyryl-cAMP have comparatively weak ability to inhibit DNA synthesis and the proliferative activity and transplantation properties of the cells.Laboratory of Biochemistry and Laboratory of Experimental Therapy of Leukemias, Central Institute of Hematology and Blood Transfusion, Ministry of Health of the USSR. Laboratory for the Search for New Antibiotics, All-Union Research Institute for the Search for New Antibiotics, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR K. V. Bunin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 3, pp. 365–367, March, 1976.