title: Annexin A8 identifies a subpopulation of transiently quiescent c-kit positive luminal progenitor cells of the ductal mammary epithelium.
abstract: We have previously shown that Annexin A8 (ANXA8) is strongly associated with the basal-like subgroup of breast cancers, including BRCA1-associated breast cancers, and poor prognosis; while in the mouse mammary gland AnxA8 mRNA is expressed in low-proliferative isolated pubertal mouse mammary ductal epithelium and after enforced involution, but not in isolated highly proliferative terminal end buds (TEB) or during pregnancy. To better understand ANXA8's association with this breast cancer subgroup we established ANXA8's cellular distribution in the mammary gland and ANXA8's effect on cell proliferation. We show that ANXA8 expression in the mouse mammary gland was strong during pre-puberty before the expansion of the rudimentary ductal network and was limited to a distinct subpopulation of ductal luminal epithelial cells but was not detected in TEB or in alveoli during pregnancy. Similarly, during late involution its expression was found in the surviving ductal epithelium, but not in the apoptotic alveoli. Double-immunofluorescence (IF) showed that ANXA8 positive (+ve) cells were ER-alpha negative (-ve) and mostly quiescent, as defined by lack of Ki67 expression during puberty and mid-pregnancy, but not terminally differentiated with ∼15% of ANXA8 +ve cells re-entering the cell cycle at the start of pregnancy (day 4.5). RT-PCR on RNA from FACS-sorted cells and double-IF showed that ANXA8+ve cells were a subpopulation of c-kit +ve luminal progenitor cells, which have recently been identified as the cells of origin of basal-like breast cancers. Over expression of ANXA8 in the mammary epithelial cell line Kim-2 led to a G0/G1 arrest and suppressed Ki67 expression, indicating cell cycle exit. Our data therefore identify ANXA8 as a potential mediator of quiescence in the normal mouse mammary ductal epithelium, while its expression in basal-like breast cancers may be linked to ANXA8's association with their specific cells of origin.
authors: Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom; Synpromics Limited, Edinburgh, United Kingdom.
authors: Juan Manuel
authors: JM
authors: Iglesias
authors: Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.
authors: Claire J
authors: CJ
authors: Cairney
authors: Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.
authors: Roderick K
authors: RK
authors: Ferrier
authors: CRUK Beatson Institute, Glasgow, United Kingdom.
authors: Laura
authors: L
authors: McDonald
authors: Medical Research Council Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom.
authors: Kelly
authors: K
authors: Soady
authors: European Cancer Stem Cell Research Institute, Cardiff School of Biosciences, Cardiff University, Cardiff, United Kingdom.
authors: Howard
authors: H
authors: Kendrick
authors: Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom; Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow, United Kingdom.
authors: Marie-Anne
authors: MA
authors: Pringle
authors: Department of Biochemistry and Molecular Biology and the Institute of Biotechnology of Asturias (IUBA), University of Oviedo, Oviedo, Spain.
authors: Reginald O
authors: RO
authors: Morgan
authors: Conway Institute and School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin, Ireland.
authors: Finian
authors: F
authors: Martin
authors: European Cancer Stem Cell Research Institute, Cardiff School of Biosciences, Cardiff University, Cardiff, United Kingdom.
authors: Matthew J
authors: MJ
authors: Smalley
authors: CRUK Beatson Institute, Glasgow, United Kingdom.
authors: Karen
authors: K
authors: Blyth
authors: Institute of Cancer Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.
authors: Torsten
authors: T
authors: Stein
mesh_terms: D000367:Age Factors; D000818:Animals; D017302:Annexins / Q000378:metabolism*; D015153:Blotting, Western; D001973:Bromodeoxyuridine; D059447:Cell Cycle Checkpoints / Q000502:physiology*; D003114:Colony-Forming Units Assay; D066026:Endothelial Progenitor Cells / Q000378:metabolism*; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D051379:Mice; D011247:Pregnancy; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D017302:Annexins; D019394:Ki-67 Antigen; D019009:Proto-Oncogene Proteins c-kit; D001973:Bromodeoxyuridine