Transfection of the nm23-H1 gene into human hepatocarcinoma cell line inhibits the expression of sialyl Lewis X, alpha1,3 fucosyltransferase VII, and metastatic potential.

Abstract

The expressions of Lewis antigens, alpha1,3 fucosyltransferase (alpha1,3 FucT)-VII, and the metastatic potential of the 7721 human hepatocarcinoma cell line after the transfection of the cDNA of nm23-H1, a known metastasis-suppressive gene, were studied using mock cells as the control, which were transfected with the pcDNA3 vectors. Cell adhesion to human umbilical vein epithelial cells (HUVEC), chemotaxic cell migration through transwells, and invasion through matrigel were selected as the metastasis-related phenotypes to assess the metastatic potential at the cell level. The results showed that the expression of SLe(x) was high, while the expression of Le(x), SDLe(x), and SLe(a) were very low on the surface of the mock cells. After transfection of nm23-H1, the expressions of SLe(x), alpha1,3 FucT-VII, and the cell adhesion to HUVEC, as well as cell migration and invasion were simultaneously decreased in all three clones of nm23-H1-transfected cells. Among different clones, the decreased expressions of SLe(x) and alpha1,3 FucT-VII were roughly correlated to each other, and also, in general, proportional to the ability of cell adhesion to HUVEC, cell migration, and invasion. The expressions of these metastasis-related phenotypes were lowest in clone 3 and highest in clone 4. Only the specific monoclonal antibody to SLe(x) (KM93) significantly abolished the cell adhesion, migration, and invasion, while other monoclonal antibodies against SDLe(x) or Le(x) and SLe(a) only slightly inhibited or entirely failed to inhibit the above-mentioned phenotypes. However, the rate of cell growth was not changed after the transfection of nm23-H1, and the ability of colony formation on the soft agar was only decreased in one clone. These findings reveal that the down-regulation of alpha1,3 FucT-VII and its product, SLe(x), is one of the mechanisms to explain the metastasis-suppressive effect of the nm23-H1 gene.