Effect of suppression of TGF-β1 expression on cell-cycle and gene expression of β-1,4- galactosyltransferase 1 in human hepatocarcinoma cells

β-1,4- galactosyltransferase 1 (β1,4-GT 1) is localized both in the Golgi complex where it catalyzes the transfer of galactose from UDP-galactose to terminal N-acetylglucosamine forming Galβ1→4GlcNAc structure, and on the cell surface where it serves as an adhesion molecule. It has previously been reported that the expression of β1,4-GT 1 was cell-cycle-specific, regulated by cell growth. Transforming growth factor-β1 (TGF-β1) could regulate cell G1/S phase transition and modulate cell growth in many types of cells. In this study, we introduced the antisense-TGF-β1 into SMMC-7721 cell, a human hepatocarcinoma cell line, for blocking its intrinsic TGF-β1 expression, and changing its cell-cycle, and then analyzed the gene expression of β1,4-GT 1 together with the β1,4-GT activity. The result showed that the antisense-TGF-β1 transfected SMMC-7721 cells (AST/7721) were growth enhanced, with more cells in S phase and less cells in G2/M phase compared with the mock transfected cells (pcDNA3/7721). At the same time, it was found that the gene expression of β1,4-GT 1 in AST/7721 was decreased to one fifth that of pcDNA3/7721, and the cell surface β1,4-GT activity was reduced to one fifth of the control, while the total activity of β1,4-GT was decreased to one half that of the control. The results indicate that suppression of TGF-β1 expression resulted in change of cell-cycle together with the decreased gene expression of β1,4-GT 1 and β1,4-GT activity in human hepatocarcinoma cells. (C) 2000 Academic Press.