Abstract
Regulating the intestinal absorption of nutrients is effective for prevention of certain diseases, including lifestyle-related diseases. However, the mechanisms of intestinal absorption are too complicated to analyze only by in vivo or in situ experiments. Studies using cultured cells are essential for revealing the characteristics and regulatory mechanisms of functional molecules such as transporters and tight junctions, which are involved in intestinal absorption. Caco-2, an intestinal epithelial cell line established from human colon adenocarcinoma tissues, expresses a variety of functions observed in small-intestinal epithelial cells. Although some of the properties of this cell line differ from those of small-intestinal cells, the transport functions of Caco-2 for hydrophobic drugs and cholesterol, for example, are well correlated with the results obtained in in vivo experiments. We have recently developed a model system for evaluating the intestinal absorption of dioxins using Caco-2 cell monolayers and dioxin-responsive HepG2 cells. This approach may be useful for searching for food substances that suppress the intestinal absorption of dioxins. As Caco-2 expresses MDR1, an efflux pump for xenobiotics, this cell line is useful for analyzing the intestinal absorption of xenobiotics and its regulation. The utility of cultured cells for analysis of molecular mechanisms and for screening experiments should be recognized.
