Growth response of colon cancer cell lines to selective estrogen receptor modulators.

BACKGROUND: The purpose of this study was to compare the "in vitro" effects of the selective estrogen receptor modulators, tamoxifen and raloxifene, on two human colon cancer cell lines. MATERIALS AND METHODS: Serial concentrations (0.1, 1, 5 and 10 microM) of tamoxifen and raloxifene were used and evaluated for cell proliferation, viability and apoptosis in HCT8 and HCT116 cells. RESULTS: Micromolar doses of raloxifene significantly reduced HCT116 and HCT8 cell proliferation. Tamoxifen (5 microM) strongly reduced HCT8 cell growth with minor effects on HCT116 cells. Raloxifene (10 microM) was lethal on both cell lines, while 10 microM tamoxifen caused lethality only in HCT8 cells. Five microM raloxifene reduced cell viability in HCT8 and HCT116 cells, while 5 microM tamoxifen halved only HCT8 cell viability. Raloxifene and tamoxifen did not induce apoptosis in the two cell lines. CONCLUSION: Tamoxifen, and even more raloxifene, were effective in reducing HCT8 and HCT116 cell proliferation and viability, suggesting their potential application in the prevention and therapy of colorectal cancer.