The expression of soluble and cell-bound α2,6 sialyltransferase in human colonic carcinoma CaCo-2 cells correlates with the degree of enterocytic differentiation

α2,6 sialyltransferase towards the N-acetyllactosaminyl sequence (α2,6 ST, E.C. 2.4.99.1) is one of the major sialyltransferases in human colonic cells; it strongly increases in human colorectal tumors and is largely expressed in fetal and neonatal rat colon. In this study we demonstrate that human colon carcinoma CaCo-2 cells,which differentiate spontaneously into enterocytes when maintained confluent for several days, exhibit a very high expression of α2,6 ST both in the cell-bound and soluble form. When the CaCo-2 cells were cultured on porous membranes the soluble α2,6 ST was mainly detected in the medium collected from the chamber corresponding to the basolateral face of the monolayer. The soluble α2,6 ST could be concentrated and purified from the α2,3 sialyltransferase by affinity chromatography on Blue Sepharose. © 1992 Academic Press, Inc.