ABSTRACT
Objective To investigate the combining anticancer effect of tamoxifen(TAM) and ?-interferon on breast cancer cells in vitro and its mechanism.Methods MCF-7 ER-positive breast cancer cell lines were treated with tamoxifen alone,or in combination with ?-interferon and/or estrogen in vitro.Cell proliferation was evaluated by MTT assay;FCM was used to determine the distribution of cell cycle,cell apoptosis and protein expression of Bcl-2,Bax,Fas,FasL,Caspase-8,and the activity of Caspase-3.Results TAM inhibited the proliferation of ER-postive breast cancer cells with cell cycle arrest in G0/G1 phase and with induction of apoptosis,and the proliferation-promoting effect of estrogen on MCF-7 was blocked by TAM.Anticancer effect of TAM was enhanced when cells were pretreated with ?-interferon for 24 hours.Bcl-2 protein expression was down-regulated and Caspase-8 was up-regulated by TAM and/or ?-interferon,but these drugs did not affect Bax,Fas,FasL protein expression and the activity of Caspase-3.Conclusions TAM has anticancer effect by inhibiting proliferation and inducing apoptosis in ER-positive breast cancer cells in vitro,and ?-interferon can enhance anticancer effect of TAM on breast cancer cells.The mechanism of these effects may be related with the down-regulation of Bcl-2 expression and up-regulation of Caspase-8 by TAM and ?-interferon.