title: Transcriptome analysis of the hormone-sensing cells in mammary epithelial reveals dynamic changes in early pregnancy.
abstract: BACKGROUND
  Alveoli, the milk-producing units of the mammary gland, are generated during pregnancy by collaboration of different epithelial cell types. We present the first analysis of transcriptional changes within the hormone sensing population during pregnancy. Hormone-receptor positive (HR+) cells play a key role in the initiation of alveologenesis as they sense systemic hormonal changes and translate these into local instructions for neighboring HR- cells. We recently showed that IGF2 is produced specifically by HR+ cells in early pregnancy, but is undetectable in the virgin state. Here, we define the transcriptome of HR+ cells in early pregnancy with the aim to elucidate additional changes that are unique for this dynamic developmental time window.
  
  
  RESULTS
  We harvested mammary glands from virgin, 3-day and 7-day pregnant mice and isolated a few hundred hormone-sensing cells per animal by FACS for microarray analysis. There was a high concordance between animals with a clear induction of cell cycle progression genes at day 3 of pregnancy and molecules involved in paracrine signalling at day 7.
  
  
  CONCLUSIONS
  These findings underscore the proliferative capacity of HR+ cells upon specific stimuli and elucidate developmentally-restricted changes in cellular communication. Since the majority of breast cancers are HR+, with a variable proportion of HR+ cells per tumor, we anticipate that this data set will aid further studies into the regulation of HR+ cell proliferation and the role of heterotypic signalling within tumors.
authors.affiliation: Laboratory of Mammary Gland Biology, National Cancer Centre Singapore, 11 Hospital Dr, Singapore, 169610, Singapore. duvini85@gmail.com.|Program in Cancer & Stem Cell Biology, Duke-NUS Graduate Medical School, 8 College, Rd, 169857, Singapore, Singapore. duvini85@gmail.com.
authors.forename: Duvini
authors.initials: D
authors.lastname: De Silva
authors.affiliation: Laboratory of Mammary Gland Biology, National Cancer Centre Singapore, 11 Hospital Dr, Singapore, 169610, Singapore. kunasegaran.kamini@gmail.com.|Program in Cancer & Stem Cell Biology, Duke-NUS Graduate Medical School, 8 College, Rd, 169857, Singapore, Singapore. kunasegaran.kamini@gmail.com.
authors.forename: Kamini
authors.initials: K
authors.lastname: Kunasegaran
authors.affiliation: Program in Cardiovascular & Metabolic Disorders, Duke-NUS Graduate Medical School, 8 College Rd, Singapore, 169857, Singapore. sujoy.ghosh@duke-nus.edu.sg.
authors.forename: Sujoy
authors.initials: S
authors.lastname: Ghosh
authors.affiliation: Laboratory of Mammary Gland Biology, National Cancer Centre Singapore, 11 Hospital Dr, Singapore, 169610, Singapore. apietersen@gmail.com.|Program in Cancer & Stem Cell Biology, Duke-NUS Graduate Medical School, 8 College, Rd, 169857, Singapore, Singapore. apietersen@gmail.com.|Department of Physiology, National University of Singapore, 21 Lower Kent Ridge Rd, Singapore, 119077, Singapore. apietersen@gmail.com.
authors.forename: Alexandra M
authors.initials: AM
authors.lastname: Pietersen
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology; D049109:Cell Proliferation; D005260:Female; D006728:Hormones / Q000378:metabolism*; D008321:Mammary Glands, Animal / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D011247:Pregnancy; D059467:Transcriptome
chemical_list: D006728:Hormones