title: Active allies: hormones, stem cells and the niche in adult mammopoiesis.
abstract: Adult stem cells are recruited in response to specific physiological demands to regenerate, repair or maintain essential cellular components of tissues, while preserving self-renewal capacity. Signals that activate adult stem cells are not simply cell autonomous and stem cells are part of a larger dynamic framework, the stem cell 'niche', which integrates systemic and local cues to sustain stem cell functionality. The mammary stem cell niche responds readily to hormonal stimuli, generating pertinent signals that activate stem cells, culminating in stem cell expansion and tissue growth. We review here current knowledge of the mammary stem cell niche with attention to the potent stimulation rendered by ovarian hormones, relevant cellular and molecular players, and the implication of a deregulated niche, for breast cancer risk.
authors.affiliation: Ontario Cancer Insitute, 610 University Avenue, Toronto, ON M5G 2M9, Canada.
authors.forename: Purna A
authors.initials: PA
authors.lastname: Joshi
authors.forename: Marco A
authors.initials: MA
authors.lastname: Di Grappa
authors.forename: Rama
authors.initials: R
authors.lastname: Khokha
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000453:epidemiology; D002454:Cell Differentiation / Q000502:physiology; D005260:Female; D012739:Gonadal Steroid Hormones / Q000502:physiology*; D006801:Humans; D008321:Mammary Glands, Animal / Q000166:cytology / Q000254:growth & development* / Q000502:physiology; D042361:Mammary Glands, Human / Q000166:cytology / Q000254:growth & development* / Q000502:physiology; D023421:Models, Animal; D012307:Risk Factors; D055153:Stem Cell Niche / Q000502:physiology*; D013234:Stem Cells / Q000502:physiology*
chemical_list: D012739:Gonadal Steroid Hormones