P27(KIP1) expression indicates that steroid receptor-positive cells are a non-proliferating, differentiated subpopulation of the normal human breast epithelium.
To test the hypothesis that steroid receptor-expressing cells are derived from the proliferative population, we examined expression of the p27(KIP1) inhibitor of cyclin-dependent kinase activity (a differentiation marker) while tracking the fate of proliferating cells in normal human breast tissue implanted into athymic nude mice using tritiated thymidine [3H]-dT. We identified a small number of cells that appeared to have divided just once before switching on p27(KIP1) expression. p27(KIP1)+ve cells also expressed steroid receptors, but not the Ki67 proliferation-associated antigen. These data support the hypothesis that steroid receptor-expressing cells are a differentiated population within the normal human breast epithelium.
Clarke
R B
RB
Clinical Research Department, Christie Hospital, M20 4BX, Manchester, UK.
Howell
A
A
Potten
C S
CS
Anderson
E
E
D000818:Animals; D015415:Biomarkers; D001940:Breast / Q000166:cytology / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002454:Cell Differentiation; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004848:Epithelium; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D025521:Tumor Suppressor Proteins
D015415:Biomarkers; C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D019394:Ki-67 Antigen; D008869:Microtubule-Associated Proteins; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27