LXRα could have the anti-proliferative effect on multiple cancer cells including breast cancer.However,the mechanisms of LXRα regulating the breast cancer cells remain unclear.This study is to investigate the different expression of LXRα,NF-κB p65 and cyclin D1 in the proliferation of human breast cancer cells.At first,LXRα,NF-κB p65 and cyclin D1 expression were detected by immunohistochemical staining in human breast cancer and paired adjacent breast tissues(n=60).As a result,the three kinds of protein were mainly expressed in cell nuclei.Among them,NF-κB p65 and cyclin D1 were higher expressed in breast cancer tissues than in adjacent tissues while LXRα was lower expressed.Then,MTT assay was used to detect the proliferation of MCF-7 cells and Western blot was used to examine the expression of the three kinds of protein.TO901317(a kind of artificial agonists against LXRs especially for LXRα)could increase LXRα expression,but decrease NF-κB p65 and cyclin D1 expression and suppress the proliferation of MCF-7cells in a dose-and time-dependent manner(P<0.05).Finally,the effects of LXRα siR NA and pyrrolidinedithiocarbamic acid(PDTC,an inhibitory of NF-κB)on TO901317 were observed respectively.LXRα siR NA could significantly decrease the up-regulation of LXRα expression and reverse the inhibited effect of TO901317 on cyclin D1 and NF-κB p65 expression and MCF-7 cell proliferation(P<0.05)while PDTC could strengthen the inhibition of cell proliferation and further down-regulate NF-κB p65 and cyclin D1 expression induced by TO901317(P<0.05),but have little effect on LXRα.In a conclusion,the expression of LXRα,NF-κB p65 and cyclin D1 plays an important role in the proliferation of human breast cancer cells,so as to provide a new method for the molecular targeting treatment of breast cancer in the future.

LXRα, NF-κB p65, cyclinD1, cell proliferation, TO901317