【Abstract】 Objective To study the effects of different levels estradiol on inhibitory of tamoxifen on human mammary cancer cells(ER+) in vitro. Methods Estrogen receptor (ER) positive MCF7 human breast cancer cell line was treated by the same level of tamoxifen and different levels of estradiol in vitro. Cell proliferation was evaluated by MTT assay. Results E2 at concentrations between 1 × 10-12 mol/L to 1× 10-7 mol / L significantly stimulated the growth of MCF 7 . TAM (10 μmol/ L) inhabited the growth of MCF7 significantly. E2 at different levels may influence inhibitory of tamoxifen on MCF7 cell lines. E2 (1×10-8 mol/L) makes inhibitory of tamoxifen on MCF7 cell lines valueless.Conclusion E2 is the risk factor of breast cancer, and the concentration around breast cancer cells may influence the effects of TAM.
Objective To understand the effect of estradiol in different concentrations on proliferation of diverse mammary primary cells in vitro. Methods The primary cells of cancer tissue, the adjacent tissue to tumors and normal mammary tissue from patiens with breast cancer were obtained using collagenase digesting method. All the tissue samples were cultivated in vitro, and were given estradiol in different concentrations. The effect of estradiol on the proliferation of those primary cells was measured by MTT. Results Estradiol remarkedly promoted the proliferation of primary cells of cancer tissue and peritumor tissue in vitro, whose ER expression were positive. Whereas, the promotion effect of estradiol on the proliferation of normal mammary primary cells was relatively weak, and there was no correlation between the promotion effect with the expression of ER in cancer tissue. Conclusion The risks of occurrence and relapse of breast cancer would increase significantly when the concentration of estradiol is no less than 103 pmol/L in vivo.