Production of CA19-9 in cultured human gastric cancer cell lines

Abstract

The mechanism of production and secretion of CA19-9 was studied on cultured human gastric cancer cell lines. Among several cell lines, KATO-III had relatively high ability to produce CA19-9 and also secreted large amounts of CEA at the same time. Distinct difference between CA19-9 and CEA, however, was found in both their kinetics of secretion into the medium and their subcellular distribution. It was revealed that CA19-9 was present in the cell surface of KATO-III by using indirect immunofluorescence technique and that CA19-9 existed as large molecular weight glycoproteins (mucin) based on gel chromatography of the spent medium and cell lysates on Sepharose CL-4B. On the other hand, CA19-9 could not be detected in glycolipids (gangliosides) fraction from KATO-III cell membranes. These findings suggest that KATO-III produces and secretes CA19-9 as glycoproteins (mucin) but not as glycolipids.