Journal of Mammary Gland Biology and Neoplasia

, Volume 10, Issue 1, pp 49–59

Epithelial Progenitors in the Normal Human Mammary Gland

  • John Stingl
  • Afshin Raouf
  • Joanne T. Emerman
  • Connie J. Eaves
Article

DOI: 10.1007/s10911-005-2540-7

Cite this article as:
Stingl, J., Raouf, A., Emerman, J.T. et al. J Mammary Gland Biol Neoplasia (2005) 10: 49. doi:10.1007/s10911-005-2540-7

Abstract

The human mammary gland is organized developmentally as a hierarchy of progenitor cells that become progressively restricted in their proliferative abilities and lineage options. Three types of human mammary epithelial cell progenitors are now identified. The first is thought to be a luminal-restricted progenitor; in vitro under conditions that support both luminal and myoepithelial cell differentiation, this cell produces clones of differentiating daughter cells that are exclusively positive for markers characteristic of luminal cells produced in vivo (i.e., keratins 8/18 and 19, epithelial cell adhesion molecule [EpCAM] and MUC1). The second type is a bipotent progenitor. It is identified by its ability to produce “mixed” colonies in single cell assays. These colonies contain a central core of cells expressing luminal markers surrounded by cells with a morphology and markers (e.g., keratin 14+) characteristic of myoepithelial cells. Serial passage in vitro of an enriched population of bipotent progenitors promotes the expansion of a third type of progenitor that is thought to be myoepithelial-restricted because it only produces cells with myoepithelial features. Luminal-restricted and bipotent progenitors can prospectively be isolated as distinct subpopulations from freshly dissociated suspensions of normal human mammary cells. Both are distinguished from many other cell types in mammary tissue by their expression of EpCAM and CD49f (α6 integrin). They are distinguished from each other by their differential expression of MUC1, which is expressed at much higher levels on the luminal progenitors. To relate the role of these progenitors to the generation of the three-dimensional tubuloalveolar structure of the mammary tree produced in vivo, we propose a model in which the commitment to the luminal versus the myoepithelial lineage may play a determining role in the generation of alveoli and ducts.

mammary stem cellscolony assaysflow cytometrycell culture

Abbreviations used

EpCAM

epithelial cell adhesion molecule

TDLU

terminal ductal lobular unit

TEB

terminal end bud

SMA

smooth muscle actin

SLC

small light cell

K

keratin

MaSC

mammary stem cell

HMEC

human mammary epithelial cell

Ma-CFC

mammary colony-forming cell

Ma-CFCLu

luminal-restricted progenitor

Ma-CFC-Me

myoepithelialrestricted progenitor

Ma-CFC-LuMe

bipotent progenitor

CALLA

common acute lymphoblastic leukemia antigen

ESA

epithelial specific antigen

BGA2

histo-blood group antigen H type 2

EGF

epidermal growth factor

FACS

fluorescenceactivated cell sorting

Copyright information

© Springer Science + Business Media, Inc. 2005

Authors and Affiliations

  • John Stingl
    • 1
    • 2
  • Afshin Raouf
    • 1
  • Joanne T. Emerman
    • 3
  • Connie J. Eaves
    • 1
    • 4
  1. 1.Terry Fox LaboratoryBritish Columbia Cancer AgencyVancouverCanada
  2. 2.StemCell Technologies Inc.VancouverCanada
  3. 3.Department of Anatomy and Cell BiologyUniversity of British ColumbiaVancouverCanada
  4. 4.The Terry Fox LaboratoryVancouverCanada