Identification of Iron‐Responsive Genes in Differentiated Caco‐2 Cells

Caco‐2 cells are an accepted in vitro model of intestinal iron absorption. To characterize the genetic response to iron‐deprivation, we performed comparative GeneChip analyses of differentiated Caco‐2 cells treated with an iron‐chelator (desferrioxamine) or high iron (FAC) for 6 or 18 hours (n=3). We utilized Affymetrix Human Genome U133A (6 and 18 hr) and U133B (18 hr) GeneChips (representing 33,000 human genes). Resulting data were analyzed utilizing different statistical approaches such as ANOVA and clustering. Some genes were significantly increased by iron chelation at 6 and 18 hours (BCL2, n‐myc downstream regulated 1, v‐fos and differentiated embryo chondrocyte expressed gene 1). Other genes were strongly induced only with 18 hours chelation (GLUT3, GLUT1, the monocarboxylic acid transporter and LDL receptor‐related protein 2 binding protein). Conversely, some genes were downregulated by iron deprivation at 18 hours (the ubiquitin carrier protein, cyclin B1 and CFTR). Of the known iron transport genes, divalent metal transporter 1 and transferrin receptor were induced by iron chelation, which exemplifies the validity of our experimental design. Thus, a large number of novel genes are regulated by cellular iron status. Some of these genes likely play uncharacterized roles in iron absorption and/or homeostasis, while others may be involved in the cellular stress‐response to iron‐deprivation.