Effect of adenosine and adenosine 5'-monophosphate on cell division of cultured mastocytoma P-815 cells.

Abstract

The growth of mouse mastocytoma P-815 cells in culture of (37.degree. C, 42 h) was inhibited by exogenous adenosine (0.2-1.0 mM) and more effectively by AMP (0.01-0.1 nM), but not by adenine. The inhibited growth (a 25% inhibition by 0.5 mM adenosine and a 80% inhibition by 0.25 mM AMP) was restored to a near control level by the addition of uridine (0.5 mM) to the medium. The pretreatment (37.degree. C, 3 h) of the cells with adenosine or AMP caused a 60% inhibition of incorporation (37.degree. C, 2 h) of [U-14C]aspartate into uracil nucleotides, accumulating 14C-orotate and orotidine. Dipyridamole, an inhibitor of adenosine uptake, and exogenous adenosine deaminase suppressed the growth inhibition induced by adenosine and AMP. 2-Chloroadenosine, which is resistant to the action of adenosine deaminase, was a more potent growth inhibitor; 3''-AMP and 2''-AMP, which are not hydrolyzed to adenosine by membrane 5''-nucleotidase, were ineffective. Adenosine 5''-sulfate and other 5''-substituted adenosines were ineffective. AMP inhibits the growth of mastocytoma P-815 cells as a result of its continous conversion to adenosine and a constant exposure of the cells to a low concentration of adenosine which readily permeates the cell membrane. Adenosine, AMP and their agarose-linked forms rapidly (37.degree. C, 20 min) elevated cellular levels of [cyclic] AMP; this effect was not suppressed by dipyridamole. Apparently adenosine and AMP act extracellularly for growth inhibition by regulating cAMP levels.