Expression of Na(+)-coupled sugar transport in HT-29 cells: modulation by glucose.
The human colon carcinoma cell line HT-29 adapted to grow in absence of glucose exhibits a typical enterocytic differentiation. In contrast, cells grown in glucose always remain undifferentiated. To investigate whether differentiated HT-29 cells express a Na(+)-dependent sugar transporter, isotopic tracer flux measurements of a non-metabolizable sugar analogue methyl alpha-D-glucoside (AMG) were undertaken. AMG accumulation in confluent monolayer of differentiated HT-29 cells was inhibited by replacement of sodium, phlorizin, phloretin, and glucose. Kinetic studies demonstrate the presence of only one Na(+)-dependent phlorizin-sensitive sugar transporter in differentiated HT-29 cells. Undifferentiated HT-29 cells cultured in the presence of glucose did not show a Na(+)-dependent AMG accumulation. As previously demonstrated for other markers of the enterocytic differentiation, this transporter has a growth-related expression. Moreover, it shares similar properties with the Na(+)-dependent glucose transport in the human fetal small intestine and colon. To demonstrate that the expression of the Na(+)-dependent sugar cotransporter can be modulated by glucose, differentiated HT-29 cells grown in glucose-free medium were switched to 25 mM glucose. In that condition the Na(+)-dependent AMG uptake was almost abolished. However, when these cells were switched back to glucose-free medium, the Na(+)-dependent AMG uptake was restored, although at a lower level. These experiments show that differentiated HT-29 cells are a good cellular model to study the regulation of the Na(+)-dependent sugar transporter.
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Institut National de la Sante et de la Recherche Médicale U 178, Villejuif, France.
D001692:Biological Transport / Q000187:drug effects; D002454:Cell Differentiation; D002460:Cell Line; D003110:Colonic Neoplasms; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D007536:Isomerism; D007700:Kinetics; D008757:Methylglucosides / Q000378:metabolism*; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D010695:Phlorhizin / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology*
D008757:Methylglucosides; D009004:Monosaccharide Transport Proteins; C027020:methylglucoside; D012964:Sodium; D010695:Phlorhizin; D005947:Glucose