Glycosyltransferases in metastasizing and non-metastasizing rat mammary tumors and the release of these enzymes in the host sera

Abstract

In order to study the role of glycosyltransferases in the process of metastasis, levels of sialyltransferase and two N-acetylglucosaminyltransferases in three established strains of spontaneously metastasizing rat mammary tumors were compared with four non-metastasizing strains. Activity of sialyltransferase was significantly lower in the metastasizing tumor, while the levels of both the N-acetylglucosaminyltransferases were comparable in the two groups. Levels of five glycosyltransferases were determined in the serially drawn sera of a group of rats bearing a representative metastasizing tumor (SMT- 2A), a representative non-metastasizing tumor (MT-W 9B) and a group of control female rats, from the day of tumor transplantation up to the 6th week of tumor development, at weekly intervals. In the sera of rats bearing SMT- 2A, the levels of sialyl-and galactosyltransferases were significantly ( P < 0.05) elevated from the 3rd to 4th week after tumor transplant; while no such elevation was observed for those bearing MT-W 9B, compared to the control group of rats. Levels of two fucosyltransferases, one N-acetylglucosaminyltransferase, were not elevated significantly in any of the tumor bearing rats. No significant change in the levels of protein-bound hexose, fucose or hexosamine was observed in these tumor bearing rats compared to control group.