Inhibition of carbohydrate incorporation in transformed cells by a cancer‐associated galactosyltransferase acceptor (CAGA)

The effect of cancer‐associated galactosyltransferase acceptor (CAGA) on incorporation of a variety of macromolecular precursors has been studied in transformed and nontransformed cells. Incorporation of [³H]‐mannose, [³H]‐galactose, and [³H]‐glucosamine into acid precipitable material after one‐hour pulse was inhibited more than 70% within four hours after exposure to CAGA in polyoma‐transformed BHK cells and within eight hours after exposure in chick embryo fibroblasts infected with a temperaturesensitive RSV mutant (Ts68) grown at the permissive temperature (CEF‐RSV 37°C). Initial short‐term rate of uptake (< one minute) and total long‐term uptake (one hour) of the labelled carbohydrates (acid‐soluble and acidinsoluble material) was inhibited less than 15% over this period. Incorporation of ¹⁴C‐leucine, ³H‐serine,³H‐uridine, and ³H‐thymidine into acid‐precipitable material was also inhibited > 85% in transformed cells, but more than 12‐hour exposure to CAGA was required before maximal inhibition was detected. Uptake of these labelled precursors was inhibition was detected. Uptake of these labelled precursors was inhibited less than 20% up to eight hours after exposure to CAGA. In nontransformed cells (BHK and CEF) incorporation of labelled monosaccharides as well as protein and nucleic acid precursors into acid‐precipitable material was reduced less than 25% up to 12 hours following exposure to CAGA. Infected CEF grown at the nonpermissive temperature (CEF‐RSV 14°C) were affected to an extent similar to other nontransformed cells. These data suggest that the specific action of CAGA on transformed cells may be due to inhibition of glycoconjugate synthesis.