Expression pattern of human ATP-binding cassette transporters in skin

ATP-binding cassette (ABC) transporters transport a variety of substrates across cellular membranes coupled with hydrolysis of ATP. Currently 49 ABC transporters consisting of seven subfamilies, ABCA, ABCB, ABCC, ABCD, ABCE, ABCF, and ABCG, have been identified in humans and they are extensively expressed in various tissues. Skin can develop a number of drug-induced toxicities' such as Stevens-Johnson syndrome and psoriasis. Concentration of drugs in the skin cells is associated with the development of adverse drug reactions. ABC transporters play important roles in absorption and disposition of drugs in the cells; however, the expression pattern of human ABC transporters in the skin has not been determined. In this study, the expression patterns of 48 human ABC transporters were determined in the human skin as well as in the liver and small intestine. Most of the ABCA, ABCB, ABCC, ABCD, ABCE, and ABCF family members were highly or moderately expressed in the skin, while ABCG family members were slightly expressed in the skin. Significant interindividual variability was also observed in the expression levels of those ATP transporters in the skin, except for ABCA5 and ABCF1, which were found to be expressed in all of the human skin samples tested in this study. In conclusion, this is the first study to identify the expression pattern of the whole human ABC family of transporters in the skin. The interindividual variability in the expression levels of ABC transporters in the human skin might be associated with drug-induced skin diseases.