Effects of the antioestrogen tamoxifen on the cell cycle kinetics of the human breast cancer cell line, MCF-7
Lykkesfeldt, A.E.; Larsen, J.K.; Christensen, I.J.; Briand, P.
British Journal of Cancer 49(6): 717-722
ISSN/ISBN: 0007-0920 PMID: 6733020 Accession: 005329518
The effect of 10-6 M tamoxifen on MCF-7 cells adapted to growth in 0.5% fetal calf serum was studied. The growth inhibitory effect of this tamoxifen concentration was abolished by simultaneous addition of 10-8 M, estradiol, indicating that tamoxifen may exert its effect via binding to the estrogen receptor. Flow cytometric cell cycle analysis of tamoxifen-treated cultures showed an increase in the proportion of cells in the G1 phase of the cell cycle. By exposing the cells to BUdR before flow cytometry the growth fraction was determined and found to be dramatically decreased in tamoxifen-treated cultures. Cells were not only arrested in the G1 phase but also in the G2 phase of the cell cycle. A few colonies of MCF-7 cells were resistant to 10 days treatment with 10-6 M tamoxifen.