Cell kinetics (SAMBA 200) of estradiol stimulated long-term phenol red withdrawn cultured breast cancer cells.

When estradiol stimulation was performed on hormone-responsive MCF-7 human breast cancer cells maintained in phenol red-containing medium until 24h before experiments, the cell number and the cell surface transferrin receptor level, an early marker of estradiol stimulation, were strongly increased. In contrast, similar treatment performed on MCF-7 cells grown in phenol red-free medium up to 12 months before experiments induced no stimulating effect on the cell number, although transferrin receptors were still enhanced. Since the appearance of transferrin receptors occurs before the cells begin DNA synthesis in late G1 phase, we assumed that the discrepancy between cell counts and cell surface transferrin receptors might involve cell kinetic perturbations. The proportion of cells in the (S + G2) phases and the duration of the cell cycle phases were analysed using the SAMBA 200 cell image processor. The data presented in this study failed to indicate any block in the cell cycle and the duration of the S and G2 phases were found to be unchanged. The lack of effect of estradiol stimulation on the growth of MCF-7 cells maintained several months without phenol red is not thus a consequence of cell cycle perturbations.