Ornithine decarboxylase and S-adenosyl methionine decarboxylase in skin fibroblasts of normal and cystic fibrosis patients.

The key enzymes in the synthesis of the naturally occurring polyamines, ornithine decarboxylase (ODC) and S-adenosyl methionine (SAM) decarboxylase, were investigated during cell growth and aging in fibroblast cultures from normal patients and patients with cystic fibrosis. A linear correlation between increased S-adenosyl methionine activity and putrescine concentration was apparent in all cell lines. A putrescine concentration of 0.8 mM was optimal for enhancement of SAM decarboxylase activity. The passage number of the cell line correlated inversely with maximal putrescine-stimulated SAM decarboxylase activity, earlier passage numbers having the highest specific activity (Fig. 1). No significant differences in basal or putrescine-stimulated SAM decarboxylase activity were noted between normal fibroblast cultures and cells from patients with cystic fibrosis (Fig. 2). SAM decarboxylase activity increased as the cell lines approached confluence. Activity was lowest during exponential growth (Fig. 3). ODC activity was increased during early exponential growth and fell as cells reached confluence (Fig. 4). No differences in ODC activity and putrescine inhibition between the normal and cystic fibrosis cell cultures at equivalent points of exponential growth were noted.