Expression, Function, and Regulation of ABCG2 on the Intestinal Epithelial Barrier Permeability.

Human breast cancer resistance protein (BCRP, gene symbol ABCG2) is an ATP-binding cassette (ABC) efflux transporter that is highly expressed on the apical membranes of intestinal epithelium and contributes to the absorption, distribution, and elimination of xenobiotics and the efflux of endogenous molecules. Also, the intestinal epithelial monolayer is the largest interface and the most important functional barrier between the internal environment and the systemic circulation. Extensive studies have demonstrated that intestinal ABCG2 of humans and rodents plays a crucial role in limiting absorption of xenobiotics, which are ABCG2 transport substrates, in the small intestine by mediating distribution in the intestinal epithelial barrier. Therefore, changes in the expression, function and activity of ABCG2 in the intestinal epithelial barrier play important roles in drug response and side effects. In this review, we specifically summarize the current research progress of ABCG2 in intestinal drug transport, intestinal urate excretion and intestinal barrier dysfunction, and its role in altering the intestinal epithelial barrier permeability in human intestinal disorder.