ABSTRACT
<p><b>AIM</b>To investigate the effects of tamoxifen on proliferation of human breast cancer Bcap-37 cells and cervical carcinoma HeLa cells and to explore it's possible mechanism.</p><p><b>METHODS</b>The techniques of cell culture, growth curves, flow cytometry and laser scanning confocal microscope were used.</p><p><b>RESULTS</b>Tamoxifen (10(-6) mol/L) shifted the growth curve of Bcap-37 cells downward, and shifted the growth curve of HeLa cells upward. Tamoxifen (10(-8) - 10(-6) mol/L) inhibited the proliferation of Bcap-37 cells in a dose-dependent manner, but stimulated the proliferation of HeLa cells in a dose-dependent manner. Bcap-37 cells appeared apoptosis when treated with tamoxifen (10(-6) mol/L), and the same dose stimulated the proliferation of HeLa cells at GI/S phases. The apoptotic rate of Bcap-37 cells was 97.5%. It blocked G1 phase of HeLa cells from 55.5% to 32.8%, and increased the S phase from 29.0% to 49.4%. Tamoxifen (10(-6) mol/L) also increased the releasing of calcium in Bcap-37 and HeLa cells.</p><p><b>CONCLUSION</b>Tamoxifen can significantly influence the proliferation of breast cancer and cervical carcinoma cells possibly by affecting cell cycle and stimulating the releasing of Ca2+ in the cells.</p>