Nuclear distribution of the Ki-67 antigen during the cell cycle: comparison with growth fraction in human breast cancer cells.
It has been claimed that the commercially available Ki-67 monoclonal antibody recognizes a nuclear antigen which is solely expressed in cycling cells. Therefore, at present, Ki-67 is increasingly used as a tool in evaluating growth fractions (GFs) of human tumors. Here we describe specific patterns in the expression and topological distribution of this antigen during the cell cycle in MCF-7 human breast cancer cells. Our results support earlier findings that the antigen belongs to a class of antigens associated with the structural organization of meta- and anaphase chromosomes, and proteins located near the cortical regions of prenucleolar bodies and nucleoli. Using 5'-bromodeoxyuridine-labeling technology, we show that the expression may be undetectably low at the onset of DNA replication. Comparison of Ki-67 fractions (KFs) and GFs as estimated from continuous 5'-bromodeoxyuridine-labeling curves revealed that KF was invariably higher than GF: in exponentially growing cov362.c14 human ovary cancer cells, KF was only 3.5% higher than GF; in MCF-7 cells, 11.3 +/- 4.6%. In MCF-7 cultures either growing under suboptimal conditions or treated with 10(-6) M tamoxifen, the difference was more pronounced. Furthermore, we evaluated the decrease of Ki-67-positive cells in nutritionally deprived and cell cycle-specific, drug-treated cultures. Since the results indicate that nonproliferating cells may retain the antigen for a considerable period of time, KF may not always be a reliable indicator of GF.
van Dierendonck
J H
JH
Department of Surgery, University Hospital, Leiden, The Netherlands.
Keijzer
R
R
van de Velde
C J
CJ
Cornelisse
C J
CJ
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface / Q000032:analysis*; D001943:Breast Neoplasms / Q000032:analysis* / Q000276:immunology / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects; D002467:Cell Nucleus / Q000032:analysis* / Q000276:immunology; D006133:Growth Substances / Q000276:immunology*; D006801:Humans; D019394:Ki-67 Antigen; D008727:Methotrexate / Q000494:pharmacology; D013629:Tamoxifen / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D006133:Growth Substances; D019394:Ki-67 Antigen; D013629:Tamoxifen; D008727:Methotrexate