title: Immunoelectron-microscopic localization of a proliferation-associated antigen Ki-67 in MCF-7 cells.
abstract: Immunocytochemistry using the monoclonal antibody Ki-67 is a commonly used method to assess proliferative activity of malignant tumours, Ki-67 reacts with proliferating cells with an antigen, whose structure, function and exact locations are unknown. We studied the subcellular location of Ki-67 in MCF-7 cells using immunoelectron microscopy. In the interphase cells, Ki-67 immunoreactivity was localized in the nucleolus, mainly in the nucleolar cortex. In particular, areas of the granular component of the nucleolus were strongly stained. Weak spot-like nucleoplasmic immunostaining was also seen outside the nucleolus. During prophase Ki-67 antigen was localized on the surfaces of the condensed chromatin and during metaphase on the surface of the chromosomes. After cell division and prior to formation of new nucleoli, Ki-67 immunoreactivity was located in the nucleoplasm. Quantification of Ki-67 immunofluorescence signal by flow cytometry revealed highest Ki-67 levels in mitotic cells. The location of Ki-67 is very similar to certain recently described proteins of nucleolar preribosomes suggesting that Ki-67 may also be a component of the preribosomes.
authors: Department of Biomedical Sciences, University of Tampere, Finland.
authors: J
authors: J
authors: Isola
authors: H
authors: H
authors: Helin
authors: O P
authors: OP
authors: Kallioniemi
mesh_terms: D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm / Q000032:analysis*; D000954:Antigens, Surface / Q000032:analysis*; D001943:Breast Neoplasms / Q000276:immunology / Q000648:ultrastructure; D004273:DNA, Neoplasm / Q000737:chemistry; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen; D016253:Microscopy, Immunoelectron; D014407:Tumor Cells, Cultured / Q000276:immunology / Q000648:ultrastructure*
chemical_list: D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D004273:DNA, Neoplasm; D019394:Ki-67 Antigen