CAMP differences between clones of high and low malignant fibrosarcoma cells.

The levels of 3',5'-cyclic adenosine monophosphate (cAMP) were measured in a high malignant and a low malignant clone of murine fibrosarcoma cells isolated from a common parent in a normal mouse fibroblasts at various stages of growth. There was an inverse correlation between the degree of malignant potential and the cAMP levels. The normal fibroblasts had the highest cAMP at all time periods measured. The high malignant cells had the lowest levels and the low malignant cells were intermediary. The degree of susceptibility of each population to the growth inhibiting effects of dibutyryl cAMP, a cAMP analogue, was also measured. There was a direct correlation between degree of malignant potential and susceptibility to growth inhibition. These findings strongly support our belief that the low malignant cells represent a state of malignancy that is intermediary between the high malignant cells and the normal fibroblasts. cAMP differences may contribute to this.