Impaired carcinoembryonic antigen release during the process of suramin-induced differentiation of the human colonic adenocarcinoma cell clone HT29-D4.
The establishment of a differentiated state of the human colic adenocarcinoma cell clone HT29-D4 can be obtained by two ways: 1) the removal of glucose and its replacement by galactose in the culture medium (Fantini et al.: Biology of the Cell 65:163-169, 1989); 2) the addition of suramin, a polyanionic compound, in the glucose-containing medium (Fantini et al.: Journal of Biological Chemistry 264:10282-10286, 1989). We investigated the release of CEA in the culture medium of glucose-deprived HT29-D4 cells (HT29-D4-Gal) and studied its alteration in suramin-treated HT29-D4 cells (HT29-D4-S). The amount of CEA released in the medium in function of time in culture of undifferentiated HT29-D4-Glu cells was very low (5 to 8 ng/10(6) cells/24 hours) and almost constant throughout the experiment whereas it increased sharply during differentiation of HT29-D4-Gal cells (380 ng/10(6) cells/24 hours after 9 days in culture). Surprisingly the amount of CEA released by differentiated HT29-D4-S cells remained very low and comparable with the one of HT29-D4-Glu cells. Moreover suramin, when added to CEA-producing HT29-D4-Gal cells, strongly inhibited its release. Radioiodination of cell surface proteins followed by immunoprecipitation using an anti-CEA monoclonal antibody showed the presence of a 180 kDa polypeptide, i.e., CEA, predominantly labeled in HT29-D4-Gal and -S cells. The total CEA cellular content was higher in HT29-D4-Glu and HT29-D4-S cells than in HT29-D4-Gal cells. When HT29-D4-Gal or -S cells were treated with the bacterial phosphatidylinositol phospholipase C (Pl-PLC) a similar level of CEA was released suggesting a similar type of CEA anchorage. The present data demonstrate that a decrease in CEA release (i.e., in HT29-D4-Glu and -S cells) corresponds to an increase in its overall cellular expression. These results are in favour of a regulatory mechanism, impaired by suramin, which determines the balance between the soluble and the membrane bound forms of CEA.
Fantini
J
J
Université d'Aix-Marseille, Centre National de la Recherche Scientifique, France.
Rognoni
J B
JB
Theveniau
M
M
Pommier
G
G
Marvaldi
J
J
D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology*; D002272:Carcinoembryonic Antigen / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D002471:Cell Transformation, Neoplastic / Q000187:drug effects*; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology*; D005455:Fluorescent Antibody Technique; D006801:Humans; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D010727:Phosphoric Diester Hydrolases / Q000494:pharmacology; D013498:Suramin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism / Q000473:pathology
D002272:Carcinoembryonic Antigen; D013498:Suramin; D010727:Phosphoric Diester Hydrolases; D043265:Phosphatidylinositol Diacylglycerol-Lyase