Mammary stem cells

  • Letter |

    This study finds that the epithelial-to-mesenchymal (EMT) transition program, which is common to both mammary gland reconstituting stem cells and mammary tumour-initiating cells, is differentially regulated by two distinct EMT factors, Slug and Snail; the findings illustrate that although they appear similar, normal tissue stem cells and tumour-initiating cells are controlled by distinct regulatory processes.

    • Xin Ye
    • , Wai Leong Tam
    •  & Robert A. Weinberg
  • Letter |

    PIK3CA mutations are associated with distinct types of human breast cancers but the cellular origin and mechanisms responsible for this heterogeneity were unclear; here, using a genetic approach in mice, PIK3CA mutations are shown to activate a genetic program directing multiple cell fates in normally lineage-restricted cell types.

    • Alexandra Van Keymeulen
    • , May Yin Lee
    •  & Cédric Blanpain
  • Letter |

    PIK3CA mutations are associated with distinct types of human breast cancers but the cellular origin and mechanisms responsible for this heterogeneity were unclear; here, using a genetic approach in mice, the PIK3CAH1047R mutation is shown to induce multipotent stem-like cells and mammary tumours with different levels of malignancy depending on the cell of origin.

    • Shany Koren
    • , Linsey Reavie
    •  & Mohamed Bentires-Alj
  • Article |

    Through the use of a novel three-dimensional imaging technique, used in conjunction with a multicolour reporter that allows lineage tracing and cell tracking of entire mammary ducts in vivo, bipotent stem cells are shown to have a central role in both puberty and long-term maintenance; in addition, long-lived luminal progenitor cells with a prominent role in ductal expansion are identified.

    • Anne C. Rios
    • , Nai Yang Fu
    •  & Jane E. Visvader
  • Letter |

    Reproductive history influences breast cancer risk but the cellular mechanisms are unclear. Here it is shown that ovarian hormones regulate the size of the mammary stem cell pool in mice. The size of this pool increases when progesterone levels increase during the reproductive cycle. Progesterone probably regulates stem cell numbers through a paracrine mechanism involving induction of RANKL and Wnt in luminal cells.

    • Purna A. Joshi
    • , Hartland W. Jackson
    •  & Rama Khokha
  • Letter |

    The ovarian hormones oestrogen and progesterone increase breast cancer risk but the cellular mechanisms are unclear. Here it is shown that the size of the mammary stem cell pool in mice is regulated by steroid hormone signalling, although these cells lack the receptors for oestrogen and progesterone. The augmented pool could lead to clonal expansion of a mutated cell, possibly accounting for the increased incidence of breast cancer associated with pregnancy.

    • Marie-Liesse Asselin-Labat
    • , François Vaillant
    •  & Jane E. Visvader