TY - JOUR
T1 - Biosynthesis of the cancer-related sialyl-α2,6-lactosaminyl epitope in colon cancer cell lines expressing β-galactoside α2,6-sialyltransferase under a constitutive promoter
AU - Dall'Olio, Fabio
AU - Chiricolo, Mariella
AU - Mariani, Erminia
AU - Facchini, Andrea
PY - 2001
Y1 - 2001
N2 - An elevation of β-galactoside α2,6-sialyltransferase (ST6Gal.I) enzyme activity and an increased α2,6-sialylation of cell membranes are among the most prominent glycosylation changes associated with colon cancer; both modifications correlate with a worse prognosis. In our previous studies, we have frequently observed a discrepancy between the ST6Gal.I level within a colon cancer sample or cell line and the respective level of reactivity with the α2,6-sialyl-specific lectin from Sambucus nigra (SNA). In this study, we have investigated quantitatively the biosynthesis of the sialyl-α2,6-lactosaminyl epitope in two colon cancer cell types expressing the ST6Gal.I cDNA under the control of a constitutive promoter. By measuring the amount of ST6Gal.I mRNA using competitive RT-PCR, the expression of α2,6-sialylated lactosaminic structures with SNA and anti-CDw75 Ig, and the presence of unsubstituted lactosaminic termini by Erythrina cristagalli lectin, we reached the following conclusions: (a) a high proportion of the cell surface lactosaminic termini remains unsubstituted, even in the presence of a very high ST6Gal.I activity. This proportion is strongly dependent on the cell type; (b) ST6Gal.I-transfected colon cancer cells do not express the CDw75 epitope; (c) the level of ST6Gal.I enzyme activity only partially correlates with the mRNA level; (d) despite the control by a constitutive promoter, the ST6Gal.I mRNA is not constantly expressed over time; and (e) a very large portion of the enzyme molecules is secreted in the extracellular milieu. These results indicate that post-transcriptional and post-translational mechanisms play a pivotal role in the control of α2,6-sialylation in colon cancer cells.
AB - An elevation of β-galactoside α2,6-sialyltransferase (ST6Gal.I) enzyme activity and an increased α2,6-sialylation of cell membranes are among the most prominent glycosylation changes associated with colon cancer; both modifications correlate with a worse prognosis. In our previous studies, we have frequently observed a discrepancy between the ST6Gal.I level within a colon cancer sample or cell line and the respective level of reactivity with the α2,6-sialyl-specific lectin from Sambucus nigra (SNA). In this study, we have investigated quantitatively the biosynthesis of the sialyl-α2,6-lactosaminyl epitope in two colon cancer cell types expressing the ST6Gal.I cDNA under the control of a constitutive promoter. By measuring the amount of ST6Gal.I mRNA using competitive RT-PCR, the expression of α2,6-sialylated lactosaminic structures with SNA and anti-CDw75 Ig, and the presence of unsubstituted lactosaminic termini by Erythrina cristagalli lectin, we reached the following conclusions: (a) a high proportion of the cell surface lactosaminic termini remains unsubstituted, even in the presence of a very high ST6Gal.I activity. This proportion is strongly dependent on the cell type; (b) ST6Gal.I-transfected colon cancer cells do not express the CDw75 epitope; (c) the level of ST6Gal.I enzyme activity only partially correlates with the mRNA level; (d) despite the control by a constitutive promoter, the ST6Gal.I mRNA is not constantly expressed over time; and (e) a very large portion of the enzyme molecules is secreted in the extracellular milieu. These results indicate that post-transcriptional and post-translational mechanisms play a pivotal role in the control of α2,6-sialylation in colon cancer cells.
KW - α2,6-sialyltransferase
KW - CDw75
KW - Colon cancer
KW - Glycosylation
KW - Glycosyltransferases
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U2 - 10.1046/j.0014-2956.2001.02536.x
DO - 10.1046/j.0014-2956.2001.02536.x
M3 - Article
C2 - 11722575
AN - SCOPUS:0035167142
VL - 268
SP - 5876
EP - 5884
JO - European Journal of Biochemistry
JF - European Journal of Biochemistry
SN - 0014-2956
IS - 22
ER -