Geburtshilfe Frauenheilkd 2008; 68 - A1
DOI: 10.1055/s-0028-1121880

Basal, luminal and myoepithelial cells: immunophenotypical and molecular characterization

H Bürger 1
  • 1Institute of Pathology, Paderborn, Germany; Cooperative Breast Cancer Center, Paderborn/Höxter

Although experimental data clearly confirm the existence of self-renewing mammary stem cells, the characteristics of such progenitor cells have never been satisfactorily defined. Using a double immunofluorescence technique for simultaneous detection of the basal cytokeratin 5, the glandular cytokeratins 8/18 and the myoepithelial differentiation marker smooth muscle actin (SMA), the presence of CK5+ cells in human adult breast epithelium could be demonstrated [1]. As proposed more than a decade ago [2], these cells have the potential to differentiate to either glandular (CK8/18+) or myoepithelial cells (SMA+) through intermediary cells (CK5+ and CK8/18+ or SMA+). We therefore proceeded on the assumption that the CK5+ cells are phenotypically and behaviourally progenitor (committed adult stem) cells of human breast epithelium. Furthermore, we furnish evidence that most of these progenitor cells are located in the luminal epithelium of the ductal lobular tree. More recent in vitro studies in human and murine mouse models confirmed these hypothetical, observational studies and further characterized these potential progenitor (stem) cells [3–7].

Based on data obtained in extensive analyses of proliferative breast disease lesions, we have come to regard usual ductal hyperplasia as a progenitor cell-derived lesion, whereas most breast cancers seem to evolve from differentiated glandular cells [8]. Double immunofluorescence experiments provide a new tool to characterize phenotypically progenitor (adult stem) cells and their progenies. This model has been shown to be of great value for a better understanding not only of normal tissue regeneration but also of proliferative breast disease. Furthermore, this model provides a new tool for unravelling further the regulatory mechanisms that govern normal and pathological cell growth [9].

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