Open AccessGenesis and evolution of high‐ploidy tumour cells evaluated by means of the proliferation markers p34 cdc2 , cyclin B1, PCNA and 3 [H]‐thymidine
Author(s) -
Baroja A.,
De La Hoz C.,
Alvarez A.,
Ispizua A.,
Bilbao J.,
De Gandarias J. M.
Publication year - 1996
Publication title -
cell proliferation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.647
H-Index - 74
eISSN - 1365-2184
pISSN - 0960-7722
DOI - 10.1046/j.1365-2184.1996.00990.x
Subject(s) - cyclin b1 , biology , cell cycle , ploidy , proliferating cell nuclear antigen , cyclin , cyclin b , thymidine , microbiology and biotechnology , mitosis , population , flow cytometry , cyclin dependent kinase 1 , cyclin d , cell , cell growth , genetics , dna , medicine , environmental health , gene
Although cell polyploidization is not an infrequent event in mammalian cells and is common in tumours, the mechanisms involved are not well understood. Using the murine B16 cell line as a model, we evaluated the role of some key proteins involved in cell cycle progression: p34 cdc2 , cyclin B1 and PCNA. By means of flow cytometry, we showed that both in modal‐ and in high‐ploidy subpopulations, almost all cells were p34 cdc2 ‐positive. In the modal‐ploidy subpopulation only 17.1% cells were cyclin B1‐positive and 85.6% PCNA‐positive; in contrast, in the high‐ploidy subpopulation up to 91.8% cells were cyclin B1‐positive and 97.3% cells were PCNA‐positive ( P < 0.001). Immunofluorescence microscopy showed that PCNA was located in the nucleus; p34 cdc2 , both in the nucleus and cytoplasm; and cyclin B1 yielded a cytoplasmic spotted pattern with a perinuclear reinforcement. After a 24‐h incubation with 3 [H]‐thymidine followed by withdrawal of the isotope, high‐ploidy cells remained labelled 8 days after thymidine withdrawal, in contrast to modalploidy cells. Taken together, our results suggest that polyploid cells are not quiescent, their cell cycle is longer than that of the modal‐ploidy population, and they maintain cyclin B1 throughout the cycle, which may contribute to their genesis by impeding the exit from mitosis.