Accumulation of adenosine 3′, 5′-monophosphate induced by prostaglandin E 1 binding to mastocytoma P-815 cells

Abstract

Addition of prostaglandin E 1 (PGE 1) to intact mouse mastocytoma P-815 cells stimulated adenosine 3', 5'-monophosphate (cAMP) accumulation and retarded cellular growth. To study the effects of prostaglandin (PG) binding on cAMP accumulation, specific [ 3H]PG binding to intact mastocytoma cells was examined. Intact mastocytoma cells have two types of binding sites for PGE 1 with high ( K d = 2.14 × 10 −9 M) and low ( k d = 1.05 × 10 −8 M) affinities and one type of binding site for PGF 2α. Mastocytoma cells, however, did not have a binding site for PGA 1 or PGD 2. The order of potencies of nonradioactive prostaglandins in competing with [ 3H]PGE 1 for binding sites was as follows: PGE 1 ⩾ PGE 2 ⪢ PGF 2α ⩾ PGA 1 ⩾ PGD 2 ⩾ PGI 2. In contrast, the relative potencies of the prostaglandins in enhancing cAMP accumulation were PGI 2 ⩾ PGE 1 ⩾ PGE 2 ⪢ PGA 1 ⩾ PGF 2 α = PGD 2, indicating that the receptors for E type and I type of PGs were different. Refractoriness of mastocytoma cells to PGE 1 stimulation of cAMP accumulation developed within 1 min of incubation of the cells at 37°, but disappeared immediately after decreasing the temperature to below 23°. A change in the number of PGE 1 receptors was not observed. cAMP concentrations were quickly restored by increasing temperatures from below 23° to 37°. This refractoriness did not develop in the presence of phosphodiesterase inhibitors. Furthermore, the activity of phosphodiesterase in mastocytoma cells was enhanced within 2 min by PGE 1 treatment.