Altered expression of sialylated carbohydrate antigens in HT29 colonic carcinoma cells

To determine whether cell growth conditions impacted carbohydrate expressio n, HT29 cells were gradually transferred from a conventional glucose-contai ning media to a glucose-free galactose containing media. Indirect immunoflu orescence on acetone fixed cells showed increased expression of sialyl Lewi s A antigen (CA19-9), sialyl Lewis C (DUPAN2) and Tn/sialyl-Tn on the surfa ce of HT29 cells grown in the glucose-free galactose containing media compa red to those grown in the glucose containing media. Sialyltransferases resp onsible for the synthesis for these sialylated epitopes were increased in t he galactose-fed HT29 cells. Media overlying the cells was subjected to iso pycnic ultracentrifugation in cesium chloride and the fractions derived fro m both glucose and galactose media with equivalent buoyant densities of 1.5 6 g/L, which are predicted to contain mucin glycoforms, were further separa ted by HPLC using a Mono-Q anion exchange column. The chromatograph of elue nt from the sample derived from the cells growing in the galactose containi ng media showed an increased peak that reacted with the anti-sialyl Lewis A antibody, CA19-9. These results show that alteration of in vitro culture c onditions may cause HT29 colonic carcinoma cells to alter the expression of sialylated carbohydrates.