title: S phase, an evolutionary chromatin condensation state from G1 to G2, in a breast epithelial cell line.
abstract: In order to better understand the changes in DNA organization during the cell cycle, we quantified the chromatin texture of breast epithelial cells and followed its evolution through a cell cycle. The diversity of quiescent cell states led us to limit this study to proliferating cell phases, and to choose a cell line with no G0 cells, the MDA AG cell line. We recently developed a methodology for characterizing in situ the cell cycle of breast epithelial cell lines using a cell image processor. This method is based on 15 densitometric and texture parameters computed on individual Feulgen-stained nuclei and on multiparametric analysis of the resulting data. Chromatin pattern assessment is based on nine texture parameters measured from grey-level co-occurrence and run-length section matrices. In the present study, texture parameter computation showed gradual and progressive modifications of nuclear texture. While discrimination of G1, G2 and M phases was possible, we could not discriminate G1 from S and S from G2. The chromatin pattern (defined by these nine parameters) in the G1 and early S phases, on the one hand, and in the late S and G2 phases, on the other hand, were similar. The parameter values of cells in the S phase progressively increased from G1 to G2. Two interphase chromatin condensation states were distinguished in these breast cells: a base state characteristic of a prereplicative stage and a very granular state characteristic of a postreplicative stage. We hypothesized that S cells are a blend of these two states, the evolution of a non-duplicated state toward a duplicated one.
authors.affiliation: Laboratoire de Cancérologie Experimentale, SDI CNRS 6194, Faculté de Médecine Nord, Marseille, France.
authors.forename: E
authors.initials: E
authors.lastname: Colomb
authors.forename: P M
authors.initials: PM
authors.lastname: Martin
mesh_terms: D005075:Biological Evolution; D001940:Breast / Q000166:cytology*; D002460:Cell Line; D002467:Cell Nucleus / Q000648:ultrastructure; D002843:Chromatin / Q000502:physiology*; D004847:Epithelial Cells; D005260:Female; D016193:G1 Phase / Q000502:physiology*; D016195:G2 Phase / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016196:S Phase / Q000502:physiology*
chemical_list: D002843:Chromatin