Differences in adenylate cyclase activities in murine normal cells and bladder tumor cells in tissue culture

Cyclic AMP may be involved in the modulation of cell growth. The present work sought to further define differences between normal cells and cancer cells in their cyclic AMP system. Mouse embryo fibroblasts and murine bladder transitional epithelium carcinoma cells were grown in vitro; at various times, adenyl cyclase activity was assayed by measuring the conversion of [α-³²P]ATP to cyclic AM³²P; stimulation by prostaglandin E₁ or sodium fluoride was also determined. Base line and fluoride stimulated enzyme activity were significantly greater in normal cells than cancer cells (P<0.01), and reached a peak at day 2; at confluency, levels in both systems decreased. Prostaglanin E₁ stimulated levels, in contrast, were greater in carcinoma cells, there being a 10 fold greater relative stimulation in these cells compared to normal cells (P<0.01). Findings of a possibly greater sensitivity in the cancer cells may be important in a therapeutic modulation of cancer growth.