Cell lineages that culminate in mammary gland development may also lead to breast cancer. Although these lineages, as well as the stem cells and progenitor cells they comprise, have been subjected to extensive study, the perturbations of these lineages that increase the risk of breast cancer have remained obscure, frustrating the search for chemoprevention drugs. Consequently, scientists based at the Princess Margaret Cancer Center in Toronto took a closer look at mammary cell lineages. These scientists now report that the proliferation of mammary gland stem cells in response to progesterone is promoted by epigenetic proteins.

This discovery was detailed in a paper (“Mammary Molecular Portraits Reveal Lineage-Specific Features and Progenitor Cell Vulnerabilities”) that appeared June 19 in the Journal of Cell Biology . This paper, which describes the comprehensive profiling of the epigenomes, transcriptomes, and proteomes of cells isolated from mice and women and high risk of developing …