Adenyl Cyclase in Normal and Transformed Fibroblasts in Tissue Culture

Abstract

The activity of the enzyme adenyl cyclase has been measured in various lines of mouse, hamster, and rat fibroblasts maintained in tissue culture.All cell lines have detectable adenyl cyclase activity.With respect to the activity of the enzyme in the presence of fluoride ions: (a) mouse embryo fibroblasts and L cells have relatively high levels of enzyme, whereas 3T3 cells derived from mouse embryo fibroblasts have low levels; (b) 3T3 cells transformed by SV40 and MSV/MuLV viruses have elevated enzyme levels, but 3T3 cells transformed by polyoma virus have slightly decreased levels; (c) hamster embryo fibroblasts and the established BHK line have relatively high levels and transformation of BHK cells by polyoma virus only slightly decreases enzyme activity; (d) rat embryo fibroblasts have the highest enzyme activity found.With respect to stimulation of the enzyme by prostaglandins, prostaglandin Ei is the most effective when tested on L cells, followed in effectiveness by prostaglandin Ez, prostaglandin Fza, and prostaglandin Bi.Prostaglandin AZ produces only a small response.Two cell lines derived from 3T3 cells by transformation with polyoma or SV40 virus are unresponsive to all prostaglandins tested.With most lines, adenyl cyclase activity remained constant during culture for 2 to 3 months.However, in rat embryo fibroblasts and SV40 (3T3) cells, the fluoride-stimulated enzyme levels (but not basal levels) fell with successive passages.The ubiquitous occurrence and the diverse effects of cyclic adenosine 3',5'-monophosphate(1, 2) have prompted the consideration of a possible role for this molecule in the regulation of cellular growth and morphology.Indeed, previous studies have indicated that cyclic AMP1 or N6,0Z'-dibutyryl cyclic AMP 1 The abbreviations used were: cyclic AMP, cyclic adenosine 3',5'-monophosphate; PGEl, prostaglandin El; PGA2, prostaglandin At; PGBI, prostaglandin B,; PGE2, prostaglandin Ez; PGF2,, prostaglandin Fto.