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

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