Possible involvement of cyclic GMP in growth control of cultured mouse cells

It is reported that relatively high concentrations of cyclic GMP or its butyrated analogues when added to quiescent Balb/c 3T3 cultures can induce a substantial increase in DNA synthesis and that within a few minutes of serum addition to quyingcent cultures the intracellular concentration of cycling GMP, as measured by two independent methods, rises by a factor of nine- to eleven-fold.

Abstract

NON-TRANSFORMED fibroblastic cells in tissue culture exist in one of two reversible growth states, a state of rapid proliferation (growing) and a state of relative quiescence (resting)1,2. Transition from a resting to a growing state can be accomplished by a variety of mitogenic agents including growth substances in animal sera, insulin and proteases. 3′, 5′-cyclic adenosine monophosphate (cyclic AMP) was implicated in this transition3,4 in that the intracellular concentrations of cyclic AMP in resting cell cultures fall after brief exposure to mitogenic agents3,4 and exogenous additions of high concentrations (10−4 to 10−3M) of dibutyryl cyclic AMP to the culture medium cause a partial reversal of the mitogenic response5. Kram and Tomkins6 have shown that exogenous additions of 3′, 5′-cyclic guanosine monophosphate (cyclic GMP) to the medium of cultured mouse cells can counteract the inhibitory effects of dibutyryl cyclic AMP upon some of the earliest events induced by a mitogenic signal (increased uptake of uridine, leucine, and 2-deoxy-glucose). We now report (1) that relatively high concentrations (10−6 to 10−4M) of cyclic GMP or its butyrated analogues when added to quiescent Balb/c 3T3 cultures can induce a substantial increase in DNA synthesis and (2) that within a few minutes of serum addition to quiescent cultures the intracellular concentration of cyclic GMP, as measured by two independent methods, rises by a factor of nine- to eleven-fold. Cyclic AMP and cyclic GMP concentrations were also measured throughout the remainder of the cell cycle.