Enkephalinase activity in the intestinal epithelial cells of the fetus of 19 days and their immortalized and transformed counterparts the SLC-cell lines.

Enkephalinase (EC 3.4.24.11), an enzyme widely distributed in brain and peripheral tissues of human and various animal species, was measured in the intestinal fetal cells and in the intestinal epithelial cells of adult rat, where its activity was respectively 96,1 +/- 10,18 fmol/mg protein and 52,27 +/- 8,43 fmol/mg protein. The immortalized cell lines: SLC-11 (after transfection with the plasmid containing oncogene from the human adenovirus type 2-E1A), SLC-21 (plasmid containing oncogene from polyoma virus) and SLC-41 (plasmid containing oncogene from simian virus 40 large tumor antigen) presented relatively strong enkephalinase activity; it was respectively 28,3 +/- 1,7, 37,9 +/- 3,6 and 49,3 +/- 3,1 fmol/mg protein. The cells of SLC-12T and SLC-44T lines, obtained after transfection with the mutant Ha-ras-1-gene and possessing tumorigene potency have the enkephalinase activity very decreased: 1,6 +/- 0,9 and 8,7 +/- 3,2 fmol/mg protein (p < 0,001). This interesting properties of the tumorigene cells may constitute a new subject of investigations in the carcinomas therapy.