Insulin and IGF-1 Receptors in A Human Intestinal Adenocarcinoma Cell Line (Caco-2): Regulation of Na+Glucose Transport Across the Brush Border

Abstract

Both insulin and IGF–1 receptors are present in intestinal mucosal cells, although their role in this tissue is unclear. We have characterized these receptors in a human adenocarcinoma cell line, Caco-2, and examined their role in the regulation of glucose transport and absorption in these cells. The Caco-2 cells demonstrated specific insulin and IGF-1 receptors. They also bound cytochalasin B, suggesting the presence of a glucose transporter-like protein. When grown on membranes, the Caco-2 cells formed columnar, bipolar cells with tight junctions. The monolayer selectively transported D-glucose, and methyl-D-glucose, with complete exclusion of L-glucose, D-mannitol and inulin. The absorption of glucose across the monolayer occurred via a Na⁺/glucose cotransporter, as indicated by a change in short circuit current after addition of glucose to the apical membrane. When examined under several conditions, neither insulin nor IGF-1 had an affect on the transport of glucose across the Caco-2 monolayer, nor the production of lactate by the cells. It is concluded that the insulin and IGF-1 receptors of Caco-2 cells do not regulate glucose transport.