title: Progestin-regulated luminal cell and myoepithelial cell-specific responses in mammary organoid culture.
abstract: Normal mammary gland development requires the coordinated proliferation and morphogenesis of both mammary luminal epithelial cells (LECs) and myoepithelial cells (MECs). Cell proliferation in cultured mammary organoids containing both LECs and MECs is not increased by progestin (R5020) or 17beta-estradiol (E2) alone or R5020+E2 but is increased by E2-regulated, mammary stroma-derived Hepatocyte growth factor (HGF) and further increased by HGF+R5020. We investigated the effects of HGF and/or R5020 on morphology and LEC- and MEC-specific in vitro proliferation in organoids. HGF-induced tubulogenesis was initiated and carried out by LECs starting with cellular extensions, followed by the formation of chains and cords, and culminating in tubule formation. MECs did not appear to have an active role in this process. Whereas HGF by itself caused maximal proliferation of LECs, HGF+R5020 produced a synergistic and specific increase in MEC proliferation. Because only LECs expressed progesterone receptors (PRs), we investigated the role of receptor activator of nuclear factor-kappaB ligand (RANKL), a progestin-induced paracrine factor, in mediating increased MEC proliferation. Quantitative RT-PCR showed that RANKL mRNA was induced by R5020 or HGF+R5020 and RANKL protein colocalized with PRs in LECs. The increased proliferation of MECs in response to HGF+R5020 could be blocked by neutralizing antibody to RANKL and reproduced by treatment with HGF plus exogenous RANKL in place of R5020. Neither R5020, nor exogenously administered RANKL increased proliferation of LECs. These results led us to conclude that RANKL, induced by progestin in PR-positive cells, is secreted and interacts with HGF to specifically increase proliferation of PR-negative MECs.
authors.affiliation: Department of Physiology, Michigan State University, East Lansing, Michigan 48824, USA. shaslam@msu.edu
authors.forename: Sandra Z
authors.initials: SZ
authors.lastname: Haslam
authors.forename: Alexis
authors.initials: A
authors.lastname: Drolet
authors.forename: Kyle
authors.initials: K
authors.lastname: Smith
authors.forename: May
authors.initials: M
authors.lastname: Tan
authors.forename: Mark
authors.initials: M
authors.lastname: Aupperlee
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004338:Drug Combinations; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D005260:Female; D017228:Hepatocyte Growth Factor / Q000494:pharmacology; D008321:Mammary Glands, Animal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D032342:Muscle Cells / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D009924:Organ Culture Techniques; D009940:Organoids / Q000187:drug effects; D019899:Paracrine Communication / Q000187:drug effects; D045167:Progesterone Congeners / Q000494:pharmacology; D011372:Progestins / Q000494:pharmacology*; D011397:Promegestone / Q000494:pharmacology; D020033:Protein Isoforms / Q000378:metabolism; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism; D053245:RANK Ligand / Q000494:pharmacology; D011980:Receptors, Progesterone / Q000378:metabolism
chemical_list: D004338:Drug Combinations; D045167:Progesterone Congeners; D011372:Progestins; D020033:Protein Isoforms; D053245:RANK Ligand; D011980:Receptors, Progesterone; D017228:Hepatocyte Growth Factor; D011397:Promegestone; D019859:Proto-Oncogene Proteins c-met