Gene expression profiles of normal human mammary cell subpopulations FACS sorted based on expression of CD49f and EpCAM

To delineate epithelial subpopulations in human mammary tissue, hematopoietic and endothelial cells were depleted from freshly isolated cell suspensions derived from reduction mammoplasties by fluorescence-activated cell sorting. The resultant Lin- population was fractionated into four distinct subpopulations using CD49f (α6-integrin) and epithelial cell adhesion molecule (EpCAM; also referred to as CD326 and ESA). Based on the immunohistochemical phenotype, and in vivo and in vitro functional assays, these subpopulations were identified as fibroblast-enriched stromal (CD49f -EpCAM-), mammary stem cell (MaSC)-enriched (CD49f hiEpCAM-), luminal progenitor (CD49f +EpCAM+), and mature luminal (CD49f –EpCAM+) cell subpopulations. Microarray profiling was used to derive gene expression signatures representative of these subpopulations using freshly sorted cells (>90% purity) from normal breast tissue. The four mammary cell subpopulations were found to have distinct gene expression profiles. Four mammary cell subpopulations from three individual patient samples were analyzed.