Amount of the two major Ag-NOR proteins, nucleolin, and protein B23 is cell-cycle dependent
✍ Scribed by Valentina Sirri; Pascal Roussel; Marie-Claude Gendron; Danièle Hernandez-Verdun
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 201 KB
- Volume
- 28
- Category
- Article
- ISSN
- 0196-4763
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✦ Synopsis
To know the biological basis allowing the use of Ag-NOR protein expression as proliferation marker in human malignancies, the relationship between cell cycle and amount of Ag-NOR protein was analyzed. The quantification of the two major Ag-NOR proteins, nucleolin and protein B23, was performed in exponentially growing, serum-deprived, and cellcycle stimulated cells. Expression of nucleolin was low in serum-deprived cells and increased mostly in S phase during cell-cycle stimulation. Conversely, expression of protein B23 was slightly repressed in serum-deprived cells, and increased progressively until G 2 phase during cell-cycle stimulation. The accumulation of nucleolin and protein B23 in G 2 compared to G 1 was demonstrated using sorted phase-specific cells. In G 0 , cells sorted according to their very low RNA content, and the amount of Ag-NOR proteins was half of that found in G 1 cells, nucleolin being only weakly detectable. Therefore, the expression of nucleolin increased between G 0 -G 1 and G 1 -S phases. These data support the hypothesis that quantification of Ag-NOR proteins is an estimation of the percentage of cells in each cell cycle phase because their amount is high in S-G 2 and low in G 1 phases.