SEPARATED HUMAN BREAST EPITHELIAL AND MYOEPITHELIAL CELLS HAVE DIFFERENT GROWTH-FACTOR REQUIREMENTS IN-VITRO BUT CAN RECONSTITUTE NORMAL BREAST LOBULOALVEOLAR STRUCTURE

In order to investigate the specific factors controlling the growth of normal breast cell types, purified populations of human breast epithe lial and myoepithelial cells from reduction mammoplasties were grown i n primary culture in three defined media and their response to foetal calf serum (FCS), epidermal growth factor (EGF) and basic fibroblast g rowth factor (FGF2) measured using MTT growth assays. Epithelial and m yoepithelial cells differed markedly in their growth requirements. Whe reas epithelial cell survival was dependent on the presence of FCS, my oepithelial cell growth was dramatically inhibited by serum. EGF and F GF2 were mitogenic for epithelial cells but not myoepithelial cells, t he addition of insulin being the only essential supplement required fo r myoepithelial cell growth. Heparin inhibited FGF2-stimulated epithel ial cell growth but also basal myoepithelial cell proliferation and th is inhibition could be overcome by the addition of EGF. Neutralizing a ntibodies to EGF also inhibited basal myoepithelial cell growth. This suggests the possibility of an autocrine role for a heparin-binding me mber of the EGF family in the growth of myoepithelial cells. Purified cells combined to form lobuloalveolar structures when incubated in a r econstituted basement membrane matrix (Matrigel)in the presence of EGF and FGF2. (C) 1997 Wiley-Liss, Inc.