Gene Expression Profiles Suggest Iron Transport Pathway in the Lactating Human Epithelial Cell

Objectives:The molecular background of iron excretion into breast milk has not been determined in humans. We determined the expression of known iron transporters in mRNA extracted from human milk fat globules to deduce which known transporters are responsible for iron excretion into human milk.Methods:The expression of iron transporters in mRNA from human milk fat globules and mouse mammary epithelial cell lines was determined by quantitative real-time polymerase chain reaction.Results:The expression of the transferrin receptor 1 (TFRC), divalent metal transporter 1 (SLC11A2), transferrin (TF), and lactoferrin (LTF) was confirmed in RNA isolated from the human milk fat globule. Similar expression was observed in the mouse mammary epithelial cell line HC11 in resting and lactating phenotypes. No iron export protein could be determined in the RNA isolated from fat globules in human breast milk and a human mammary epithelial cell line.Conclusions:The lack of iron exporters in the human mammary epithelia, in conjunction with the presence of lactoferrin suggests that transmembrane transport is not a major route of iron excretion into human milk.