ABSTRACT
Objective: To investigate the enhancing effect of ?-interferon on anticancer effect of tamoxifen against breast cancer cells in vitro. Methods: ER-positive MCF-7 and ER-negative MDA-MB-231 breast cancer cell lines were treated with tamoxifen alone, or in combination with ?-interferon or estrogen in vitro. Cell proliferation was evaluated by MTT assay; distribution of cell cycle was determined by flow cytometry( FCM) and cell apoptosis was determined by DNA gel electrophoresis and FCM. Results: Tamoxifen inhibited the growth of ER-negtive and-positive brest cancer cells, induced G0/G1 phase arrest and induced cell apoptosis. Tamoxifen at same concentration had stronger inhibitory effect on ER-positive cells than ER-negative ones. Promoting effect of estrogen on MCF-7 growth was blocked by TAM, but inhibition of MDA-MB-231 by TAM was not related to estrogen. Anticancer effect of TAM was enhanced when cells were pre-treated with ?-interferon for 24 h. Conclusion: TAM exerts its anti-cancer effect through inhibiting proliferation and inducing apoptosis of ER-positive/negative breast cancer cells in vitro, and ?-interferon can enhance this manticancer effect of TAM on breast cancer cells.