The effect of butyrate on sulfated glycoprotein biosynthesis by human kidney tumor cells

Human kidney tumor cells in culture incorporate [3H]glucosamine and 35SO4 into several classes of glycoconjugate products. After a 24-h labeling period, the 3H/35S-glycosaminoglycans and 3H-glycoproteins synthesized were found associated with both the cell layer and the culture medium. These tumor cells also synthesized a class of 35S-glycoproteins which contained alkali-stable 35S-oligosaccharide chains. These 35S-glycoproteins did not accumulate with the cell layers but were preferentially found in the culture medium (82-96%). After treatment with 2.5 mM butyrate for 24 h, the tumor cells assumed a more flattened and spread morphology with more clearly defined cell borders. These butyrate-treated cell cultures showed less than a 2-fold increase in the cell-associated form of both 3H/35S-glycosaminoglycans and 3H-glycoproteins, compared to cells cultured in the absence of butyrate. In contrast, butyrate-treated cell cultures had a 3-fold increase in the total incorporation of 35SO4 into glycoproteins and a dramatic 10-30-fold increase in the cell-associated form of these 35S-glycoprotein products as compared to untreated cell cultures.