Non-proteolytic release of carcinoembryonic antigen from normal human colonic epithelial cells cultured in collagen gel.

摘要: Recent studies have shown that, even with a minimal content of carcinoembryonic antigen (CEA), normal human colonic epithelial cells express substantial amounts CEA mRNA and mucosal fragments cultured in vitro produce quite actively, indicating that should no longer be considered to an oncofetal nature. To understand the basis usefulness as tumor marker, we analyzed release CEA, glycosyl-phosphatidylinositol (GPI)-anchored protein, from cells, by culturing isolated crypts collagen gel. The appeared preserve their morphological biochemical integrity gel for at least 16 hr, released spontaneously. Three forms CEA—spontaneously liberated phosphatidylinositol-specific phospholipase C (PI-PLC) cell lysates—were indistinguishable on SDS-PAGE. This is contrast recombinant spontaneously CHO transfectants, which showed smaller molecular mass than PI-PLC-cleaved CEA. By phase separation using Triton X-114, lysates was separated mostly into detergent phase, while were aqueous phase. When metabolically labeled precursors GPI-anchor, 3H-ethanolamine but not JH-palmitic acid found These findings suggest proteolysis-like non-proteolytic cleavage, probably occurs through action some endogenous phospholipase. © 1994 Wiley-Liss, Inc.