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- Title
Notch-induced mammary tumorigenesis does not involve the lobule-limited epithelial progenitor.
- Authors
Bruno, R D; Boulanger, C A; Smith, G H
- Abstract
The mouse mammary epithelial cell hierarchy contains both multipotent stem cell as well as lineage-limited duct and lobular progenitor cell functions. The latter-also termed parity-identified mammary epithelial cells (PI-MECs)-are marked by beta-galactosidase (β Gal) expression following pregnancy and involution in whey acidic protein promoter (WAP)-Cre/Rosa26-flox-stop-flox-lacZ (WC/R26) mice, and are the targets of tumorigenic transformation in mouse mammary tumor virus-erbB2 transgenic mice. In this study, we demonstrate that an epithelial population distinct from PI-MECs is transformed during WAP-Int3 tumorigenesis. As expected, WAP-Int3/WC/R26 triple-transgenic mice failed to undergo secretory alveolar development, failed to lactate and developed mammary tumors. Following pregnancy and involution, β Gal+ mammary epithelial cells were found in the normal mammary tissue, but the resulting mammary tumors were all β Gal−. WAP-Int3/WC/R26 mammary glands contained ample estrogen receptor alpha (ERα)+ MECs, but only rare (<1%) progesterone receptor (PR)+ and RANKL+ cells. In addition, dissociated MECs from WAP-Int3/WC/R26 glands failed to regenerate a mammary tree upon transplantation into a cleared fat-pad of a nu/nu recipient mouse. However, when mixed with normal MECs, PI-MECs from WAP-Int3/WC/R26 mice contributed progeny to the resulting functional outgrowth. The WAP-Int3/WC/R26-derived PI-MECs displayed all of the properties of fully functional lobular progenitors including giving rise to ERα+, PR+, smooth muscle actin+ and RANKL+ epithelial progeny. These results demonstrate that WAP-Int3 has no oncogenic effect upon PI-MECs and that the expansion of functional lobular progenitors is required for secretory alveolar development and lactation. Furthermore, lobular progenitor function is ultimately controlled by signals within its microenvironment.
- Subjects
CARCINOGENESIS; EPITHELIAL cells; MULTIPOTENT stem cells; BETA-galactosidase; GENE expression; GENETIC transformation; ESTROGEN receptors; LABORATORY mice
- Publication
Oncogene, 2012, Vol 31, Issue 1, p60
- ISSN
0950-9232
- Publication type
Article
- DOI
10.1038/onc.2011.215