ORNITHINE DECARBOXYLASE AND TYROSINE KINASE-ACTIVITY IN JUVENILE POLYPS OF CHILDHOOD

Juvenile polyps (JP) are the most common colonic tumor in children. Al though considered benign, malignant transformation has been reported i n JP. Ornithine decarboxylase (ODC) and tyrosine kinase (TyK) enzymes are markers for a rapid cell proliferation index. DNA aneuploidy score and p53 gene expression are late malignant changes seen in patients w ith colon cancer. In this study, we investigated ODC and TyK activitie s as well as DNA aneuploidy score and p53 expression in juvenile polyp s compared with the adjacent normal colonic mucosa. Results showed tha t ODC was significantly increased in JP compared with the adjacent nor mal colonic mucosa. TyK activity was increased in 3/5 polyps and decre ased in 2/5 polyps compared with the mucosa. Mean TyK activity was hig her in JP compared with normal mucosa but did not reach significance ( 707 and 632 pmol/mg pmol, respectively). Moreover, changes in phosphor ylization of TyK proteins was also observed in JP but not in normal mu cosa. JP had a normal DNA aneuploidy score and showed no expression of p53 gene. We conclude that JP do not express p53 gene and aneuploidy but had higher activity of ODC and TyK enzymes, suggesting a higher st age of cell proliferation.